Updated at 2024-11-01 03:30:06.801906

Overview

What is Tarantool?

Tarantool combines an in-memory DBMS and a Lua server in a single platform providing ACID-compliant storage. It comes in two editions: Community and Enterprise. The use cases for Tarantool vary from ultra-fast cache to product data marts and smart queue services.

Here are some of Tarantool’s key characteristics:

Tarantool allows executing code alongside data, which helps increase the speed of operations. Developers can implement any business logic with Lua, and a single Tarantool instance can also receive SQL requests.

Tarantool has a variety of compatible modules (Lua rocks). You can pick the ones that you need and install them manually.

Tarantool runs on Linux (x86_64, aarch64), macOS (x86_64, aarch64), and FreeBSD (x86_64).

You can use Tarantool with a programming language you’re familiar with. For this purpose, a number of connectors are provided.

Editions

Tarantool comes in two editions: the open-source Community Edition (CE) and the commercial Enterprise Edition (EE).

Tarantool Community Edition

Tarantool Community Edition lets you develop applications and speed up a system in operation. It features synchronous replication, affords easy scalability, and includes tools to develop efficient applications. The Tarantool community helps with any practical questions regarding the Community Edition.

Tarantool Enterprise Edition

Tarantool Enterprise Edition provides advanced tools for administration, deployment, and security management, along with premium support services. This edition includes all the Community Edition features and is more predictable in terms of solution cost and maintenance. The Enterprise Edition is shipped as an SDK and includes a number of closed-source modules.

Примечание

In this documentation, topics related to Enterprise Edition features are marked with an Enterprise Edition admonition.

Enterprise-версия предлагает дополнительные возможности по разработке и эксплуатации кластерных приложений, например:

Enterprise-версия распространяется в форме SDK, который включает следующие ключевые компоненты:

  • Расширенная Enterprise-версия утилиты tt.
  • Tarantool Cluster Manager – визуальный веб-инструмент для управления кластерами Tarantool.

Use cases

Fast first-class storage

  • Primary storage
    • No secondary storage required
  • Tolerance to high write loads
  • Support of relational approaches
  • Composite secondary indexes
    • Data access, data slices
  • Predictable request latency

Advanced cache

  • Write-behind caching
  • Secondary index support
  • Complex invalidation algorithm support

Smart queue

  • Support of various identification techniques
  • Advanced task lifecycle management
    • Task scheduling
    • Archiving of completed tasks

Data-centric applications

  • Arbitrary data flows from many sources
  • Incoming data processing
  • Storage
  • Background cycle processing
    • Scheduling support

Руководство для начинающих

This section will get you acquainted with Tarantool.

Installing Tarantool

This section explains how to download and set up Tarantool Enterprise Edition and run a sample application provided with it. To learn how to download and install Tarantool Community Edition, see the Download page.

Примечание

The tt utility provides the ability to install and work with multiple Tarantool versions.

Системные требования

Ниже представлены рекомендуемые системные требования для запуска Tarantool Enterprise.

Требования к аппаратному обеспечению

Чтобы обеспечить полную отказоустойчивость системы распределенного хранения данных, необходимы как минимум три физических компьютера или виртуальных сервера.

For testing/development purposes, the system can be deployed using a smaller number of servers. However, it is not recommended to use such configurations for production.

Требования к программному обеспечению

  1. Tarantool Enterprise поддерживает операционные системы Red Hat Enterprise Linux и CentOS версии 7.5 и выше.

    Примечание

    Tarantool Enterprise может работать на других дистрибутивах Linux на основе systemd, но тестирование на них не проводится, поэтому корректная работа не гарантирована.

  2. Требуется glibc версии 2.17-260.el7_6.6 и выше. Необходимо проверить текущую версию и обновить в случае необходимости:

    $ rpm -q glibc
glibc-2.17-196.el7_4.2
$ yum update glibc

Сетевые требования

Здесь и далее по тексту под серверами хранения данных или серверами Tarantool понимаются компьютеры, которые используются для хранения и обработки данных, а под сервером администрирования понимается компьютер, с помощью которого оператор устанавливает и настраивает систему.

Кластер Tarantool работает по принципам полносвязной топологии (full mesh topology), поэтому все серверы Tarantool должны поддерживать прием и передачу данных по TCP и UDP на всех портах, которые используются экземплярами кластера (см. настройки advertise_uri: <host>:<port> и config: advertise_uri: '<host>:<port>' в файле /etc/tarantool/conf.d/*.yml для каждого экземпляра). Например:

# /etc/tarantool/conf.d/*.yml

myapp.s2-replica:
  advertise_uri: localhost:3305 # this is a TCP/UDP port
  http_port: 8085

all:
  ...
  hosts:
    storage-1:
      config:
        advertise_uri: 'vm1:3301' # this is a TCP/UDP port
        http_port: 8081

Чтобы настроить удаленный мониторинг или подключиться по административной консоли, сервер администрирования должен иметь доступ к следующим TCP-портам на серверах Tarantool:

  • 22 – чтобы использовать SSH-протокол;
  • ports specified in instance configuration to monitor the HTTP-metrics.

Кроме того, рекомендуется применить следующие настройки для sysctl на всех серверах Tarantool:

$ # TCP KeepAlive setting
$ sysctl -w net.ipv4.tcp_keepalive_time=60
$ sysctl -w net.ipv4.tcp_keepalive_intvl=5
$ sysctl -w net.ipv4.tcp_keepalive_probes=5

Эта необязательная настройка сетевого стека Linux помогает ускорить решение проблем с сетевым подключением при физическом отказе сервера. Для достижения максимальной производительности может также потребоваться настройка других параметров сетевого стека, которые не относятся к СУБД Tarantool. Для получения дополнительной информации обратитесь к разделу Руководство по оптимизации сетевой производительности (Network Performance Tuning Guide) в пользовательской документации по RHEL7.

Комплектация

The latest release packages of Tarantool Enterprise are available in the customer zone at Tarantool website. Please contact support@tarantool.io for access.

Каждый пакет представляет собой архив tar + gzip и включает в себя следующие компоненты и функции:

Содержимое архива:

Установка

Готовый архив tar + gzip необходимо загрузить на сервер и распаковать:

$ tar xvf tarantool-enterprise-sdk-<version>.tar.gz

Дополнительная установка не требуется, поскольку распакованные бинарные файлы практически готовы к работе. Перейдите в каталог с бинарными файлами (tarantool-enterprise) и добавьте их в путь для поиска исполняемых файлов, запустив скрипт из дистрибутива:

$ source ./env.sh

Убедитесь, что вы можете запускать данный скрипт, а также что файл со скриптом является исполняемым. В противном случае задайте разрешения в помощью команд chmod и chown.

Создаем свою первую базу данных на Tarantool

Example on GitHub: create_db

In this tutorial, you create a Tarantool database, write data to it, and select data from this database.

Prerequisites

Before starting this tutorial:

Creating an application

The tt create command can be used to create an application from a predefined or custom template. In this tutorial, the application layout is prepared manually:

  1. Create a tt environment in the current directory using the tt init command.

  2. Inside the instances.enabled directory of the created tt environment, create the create_db directory.

  3. Inside instances.enabled/create_db, create the instances.yml and config.yaml files:

    • instances.yml specifies instances to run in the current environment. In this example, there is one instance:

      instance001:

    • config.yaml contains basic instance configuration:

      groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'

      The instance in the configuration accepts incoming requests on the 3301 port.

Working with the database

Starting an instance

  1. Start the Tarantool instance from the tt environment directory using tt start:

    $ tt start create_db

  2. To check the running instance, use the tt status command:

    $ tt status create_db
INSTANCE                       STATUS      PID   MODE
create_db:instance001          RUNNING     54560 RW

  3. Connect to the instance with tt connect:

    $ tt connect create_db:instance001
   • Connecting to the instance...
   • Connected to create_db:instance001

create_db:instance001>

    This command opens an interactive Tarantool console with the create_db:instance001> prompt. Now you can enter requests in the command line.

Creating a space

  1. Create a space named bands:

    create_db:instance001> box.schema.space.create('bands')
---
- engine: memtx
  before_replace: 'function: 0x010229d788'
  field_count: 0
  is_sync: false
  is_local: false
  on_replace: 'function: 0x010229d750'
  temporary: false
  index: []
  type: normal
  enabled: false
  name: bands
  id: 512
- created
...

  2. Форматируйте созданный спейс, указывая имена и типы полей:

    create_db:instance001> box.space.bands:format({
                           { name = 'id', type = 'unsigned' },
                           { name = 'band_name', type = 'string' },
                           { name = 'year', type = 'unsigned' }
                       })
---
...

Creating indexes

  1. Create the primary index based on the id field:

    create_db:instance001> box.space.bands:create_index('primary', { parts = { 'id' } })
---
- unique: true
  parts:
  - fieldno: 1
    sort_order: asc
    type: unsigned
    exclude_null: false
    is_nullable: false
  hint: true
  id: 0
  type: TREE
  space_id: 512
  name: primary
...

  2. Create the secondary index based on the band_name field:

    create_db:instance001> box.space.bands:create_index('secondary', { parts = { 'band_name' } })
---
- unique: true
  parts:
  - fieldno: 2
    sort_order: asc
    type: string
    exclude_null: false
    is_nullable: false
  hint: true
  id: 1
  type: TREE
  space_id: 512
  name: secondary
...

Writing and selecting data

  1. Insert three tuples into the space:

    create_db:instance001> box.space.bands:insert { 1, 'Roxette', 1986 }
---
- [1, 'Roxette', 1986]
...
create_db:instance001> box.space.bands:insert { 2, 'Scorpions', 1965 }
---
- [2, 'Scorpions', 1965]
...
create_db:instance001> box.space.bands:insert { 3, 'Ace of Base', 1987 }
---
- [3, 'Ace of Base', 1987]
...

  2. Select a tuple using the primary index:

    create_db:instance001> box.space.bands:select { 3 }
---
- - [3, 'Ace of Base', 1987]
...

  3. Select tuples using the secondary index:

    create_db:instance001> box.space.bands.index.secondary:select{'Scorpions'}
---
- - [2, 'Scorpions', 1965]
...

Creating a sharded cluster

Example on GitHub: sharded_cluster_crud

In this tutorial, you get a sharded cluster up and running on your local machine and learn how to manage the cluster using the tt utility. This cluster uses the following external modules:

The cluster created in this tutorial includes 5 instances: one router and 4 storages, which constitute two replica sets.

Cluster topology

Prerequisites

Before starting this tutorial:

Creating a cluster application

The tt create command can be used to create an application from a predefined or custom template. For example, the built-in vshard_cluster template enables you to create a ready-to-run sharded cluster application.

In this tutorial, the application layout is prepared manually:

  1. Create a tt environment in the current directory by executing the tt init command.

  2. Inside the empty instances.enabled directory of the created tt environment, create the sharded_cluster_crud directory.

  3. Inside instances.enabled/sharded_cluster_crud, create the following files:

    • instances.yml specifies instances to run in the current environment.
    • config.yaml specifies the cluster configuration.
    • storage.lua contains code specific for storages.
    • router.lua contains code specific for a router.
    • sharded_cluster_crud-scm-1.rockspec specifies external dependencies required by the application.

    The next Developing the application section shows how to configure the cluster and write code for routing read and write requests to different storages.

Developing the application

Configuring instances to run

Open the instances.yml file and add the following content:

storage-a-001:
storage-a-002:
storage-b-001:
storage-b-002:
router-a-001:

This file specifies instances to run in the current environment.

Configuring the cluster

This section describes how to configure the cluster in the config.yaml file.

Step 1: Configuring credentials

Add the credentials configuration section:

credentials:
  users:
    replicator:
      password: 'topsecret'
      roles: [ replication ]
    storage:
      password: 'secret'
      roles: [ sharding ]

In this section, two users with the specified passwords are created:

  • The replicator user with the replication role.
  • The storage user with the sharding role.

These users are intended to maintain replication and sharding in the cluster.

Важно

It is not recommended to store passwords as plain text in a YAML configuration. Learn how to load passwords from safe storage such as external files or environment variables from Loading secrets from safe storage.

Step 2: Specifying advertise URIs

Add the iproto.advertise section:

iproto:
  advertise:
    peer:
      login: replicator
    sharding:
      login: storage

In this section, the following options are configured:

  • iproto.advertise.peer specifies how to advertise the current instance to other cluster members. In particular, this option informs other replica set members that the replicator user should be used to connect to the current instance.
  • iproto.advertise.sharding specifies how to advertise the current instance to a router and rebalancer.

The cluster topology defined in the following section also specifies the iproto.advertise.client option for each instance. This option accepts a URI used to advertise the instance to clients. For example, Tarantool Cluster Manager uses these URIs to connect to cluster instances.

Step 3: Configuring bucket count

Specify the total number of buckets in a sharded cluster using the sharding.bucket_count option:

sharding:
  bucket_count: 1000

Step 4: Defining the cluster topology

Define the cluster topology inside the groups section. The cluster includes two groups:

  • storages includes two replica sets. Each replica set contains two instances.
  • routers includes one router instance.

Here is a schematic view of the cluster topology:

groups:
  storages:
    replicasets:
      storage-a:
        # ...
      storage-b:
        # ...
  routers:
    replicasets:
      router-a:
        # ...

  1. To configure storages, add the following code inside the groups section:

    storages:
  roles: [ roles.crud-storage ]
  app:
    module: storage
  sharding:
    roles: [ storage ]
  replication:
    failover: manual
  replicasets:
    storage-a:
      leader: storage-a-001
      instances:
        storage-a-001:
          iproto:
            listen:
            - uri: '127.0.0.1:3302'
            advertise:
              client: '127.0.0.1:3302'
        storage-a-002:
          iproto:
            listen:
            - uri: '127.0.0.1:3303'
            advertise:
              client: '127.0.0.1:3303'
    storage-b:
      leader: storage-b-001
      instances:
        storage-b-001:
          iproto:
            listen:
            - uri: '127.0.0.1:3304'
            advertise:
              client: '127.0.0.1:3304'
        storage-b-002:
          iproto:
            listen:
            - uri: '127.0.0.1:3305'
            advertise:
              client: '127.0.0.1:3305'

    The main group-level options here are:

    • roles: This option enables the roles.crud-storage role provided by the CRUD module for all storage instances.
    • app: The app.module option specifies that code specific to storages should be loaded from the storage module. This is explained below in the Adding storage code section.
    • sharding: The sharding.roles option specifies that all instances inside this group act as storages. A rebalancer is selected automatically from two master instances.
    • replication: The replication.failover option specifies that a leader in each replica set should be specified manually.
    • replicasets: This section configures two replica sets that constitute cluster storages.

  2. To configure a router, add the following code inside the groups section:

    routers:
  roles: [ roles.crud-router ]
  app:
    module: router
  sharding:
    roles: [ router ]
  replicasets:
    router-a:
      instances:
        router-a-001:
          iproto:
            listen:
            - uri: '127.0.0.1:3301'
            advertise:
              client: '127.0.0.1:3301'

    The main group-level options here are:

    • roles: This option enables the roles.crud-router role provided by the CRUD module for a router instance.
    • app: The app.module option specifies that code specific to a router should be loaded from the router module. This is explained below in the Adding router code section.
    • sharding: The sharding.roles option specifies that an instance inside this group acts as a router.
    • replicasets: This section configures a replica set with one router instance.

Resulting configuration

The resulting config.yaml file should look as follows:

credentials:
  users:
    replicator:
      password: 'topsecret'
      roles: [ replication ]
    storage:
      password: 'secret'
      roles: [ sharding ]

iproto:
  advertise:
    peer:
      login: replicator
    sharding:
      login: storage

sharding:
  bucket_count: 1000

groups:
  storages:
    roles: [ roles.crud-storage ]
    app:
      module: storage
    sharding:
      roles: [ storage ]
    replication:
      failover: manual
    replicasets:
      storage-a:
        leader: storage-a-001
        instances:
          storage-a-001:
            iproto:
              listen:
              - uri: '127.0.0.1:3302'
              advertise:
                client: '127.0.0.1:3302'
          storage-a-002:
            iproto:
              listen:
              - uri: '127.0.0.1:3303'
              advertise:
                client: '127.0.0.1:3303'
      storage-b:
        leader: storage-b-001
        instances:
          storage-b-001:
            iproto:
              listen:
              - uri: '127.0.0.1:3304'
              advertise:
                client: '127.0.0.1:3304'
          storage-b-002:
            iproto:
              listen:
              - uri: '127.0.0.1:3305'
              advertise:
                client: '127.0.0.1:3305'
  routers:
    roles: [ roles.crud-router ]
    app:
      module: router
    sharding:
      roles: [ router ]
    replicasets:
      router-a:
        instances:
          router-a-001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
              advertise:
                client: '127.0.0.1:3301'

Adding storage code

Open the storage.lua file and define a space and indexes inside box.watch() as follows:

box.watch('box.status', function()
    if box.info.ro then
        return
    end

    box.schema.create_space('bands', {
        format = {
            { name = 'id', type = 'unsigned' },
            { name = 'bucket_id', type = 'unsigned' },
            { name = 'band_name', type = 'string' },
            { name = 'year', type = 'unsigned' }
        },
        if_not_exists = true
    })
    box.space.bands:create_index('id', { parts = { 'id' }, if_not_exists = true })
    box.space.bands:create_index('bucket_id', { parts = { 'bucket_id' }, unique = false, if_not_exists = true })
end)
  • The box.schema.create_space() function creates a space. Note that the created bands space includes the bucket_id field. This field represents a sharding key used to partition a dataset across different storage instances.
  • space_object:create_index() creates two indexes based on the id and bucket_id fields.

Adding router code

Open the router.lua file and load the vshard module as follows:

local vshard = require('vshard')

Configuring build settings

Open the sharded_cluster_crud-scm-1.rockspec file and add the following content:

package = 'sharded_cluster_crud'
version = 'scm-1'
source  = {
    url = '/dev/null',
}

dependencies = {
    'vshard == 0.1.27',
    'crud == 1.5.2'
}
build = {
    type = 'none';
}

The dependencies section includes the specified versions of the vshard and crud modules. To install dependencies, you need to build the application.

Building the application

In the terminal, open the tt environment directory. Then, execute the tt build command:

$ tt build sharded_cluster_crud
   • Running rocks make
No existing manifest. Attempting to rebuild...
   • Application was successfully built

This installs the vshard and crud modules defined in the *.rockspec file to the .rocks directory.

Working with the cluster

Starting instances

To start all instances in the cluster, execute the tt start command:

$ tt start sharded_cluster_crud
   • Starting an instance [sharded_cluster_crud:storage-a-001]...
   • Starting an instance [sharded_cluster_crud:storage-a-002]...
   • Starting an instance [sharded_cluster_crud:storage-b-001]...
   • Starting an instance [sharded_cluster_crud:storage-b-002]...
   • Starting an instance [sharded_cluster_crud:router-a-001]...

Bootstrapping a cluster

After starting instances, you need to bootstrap the cluster as follows:

  1. Connect to the router instance using tt connect:

    $ tt connect sharded_cluster_crud:router-a-001
   • Connecting to the instance...
   • Connected to sharded_cluster_crud:router-a-001

  2. Call vshard.router.bootstrap() to perform the initial cluster bootstrap and distribute all buckets across the replica sets:

    sharded_cluster_crud:router-a-001> vshard.router.bootstrap()
---
- true
...

Checking the cluster status

To check the cluster status, execute vshard.router.info() on the router:

sharded_cluster_crud::router-a-001> vshard.router.info()
---
- replicasets:
    storage-b:
      replica:
        network_timeout: 0.5
        status: available
        uri: storage@127.0.0.1:3305
        name: storage-b-002
      bucket:
        available_rw: 500
      master:
        network_timeout: 0.5
        status: available
        uri: storage@127.0.0.1:3304
        name: storage-b-001
      name: storage-b
    storage-a:
      replica:
        network_timeout: 0.5
        status: available
        uri: storage@127.0.0.1:3303
        name: storage-a-002
      bucket:
        available_rw: 500
      master:
        network_timeout: 0.5
        status: available
        uri: storage@127.0.0.1:3302
        name: storage-a-001
      name: storage-a
  bucket:
    unreachable: 0
    available_ro: 0
    unknown: 0
    available_rw: 1000
  status: 0
  alerts: []
...

The output includes the following sections:

  • replicasets: contains information about storages and their availability.
  • bucket: displays the total number of read-write and read-only buckets that are currently available for this router.
  • status: the number from 0 to 3 that indicates whether there are any issues with the cluster. 0 means that there are no issues.
  • alerts: might describe the exact issues related to bootstrapping a cluster, for example, connection issues, failover events, or unidentified buckets.

Writing and selecting data

  1. To insert sample data, call crud.insert_many() on the router:

    crud.insert_many('bands', {
    { 1, box.NULL, 'Roxette', 1986 },
    { 2, box.NULL, 'Scorpions', 1965 },
    { 3, box.NULL, 'Ace of Base', 1987 },
    { 4, box.NULL, 'The Beatles', 1960 },
    { 5, box.NULL, 'Pink Floyd', 1965 },
    { 6, box.NULL, 'The Rolling Stones', 1962 },
    { 7, box.NULL, 'The Doors', 1965 },
    { 8, box.NULL, 'Nirvana', 1987 },
    { 9, box.NULL, 'Led Zeppelin', 1968 },
    { 10, box.NULL, 'Queen', 1970 }
})

    Calling this function distributes data evenly across the cluster nodes.

  2. To get a tuple by the specified ID, call the crud.get() function:

    sharded_cluster_crud:router-a-001> crud.get('bands', 4)
---
- rows:
  - [4, 161, 'The Beatles', 1960]
  metadata: [{'name': 'id', 'type': 'unsigned'}, {'name': 'bucket_id', 'type': 'unsigned'},
    {'name': 'band_name', 'type': 'string'}, {'name': 'year', 'type': 'unsigned'}]
- null
...

  3. To insert a new tuple, call crud.insert():

    sharded_cluster_crud:router-a-001> crud.insert('bands', {11, box.NULL, 'The Who', 1962})
---
- rows:
  - [11, 652, 'The Who', 1962]
  metadata: [{'name': 'id', 'type': 'unsigned'}, {'name': 'bucket_id', 'type': 'unsigned'},
    {'name': 'band_name', 'type': 'string'}, {'name': 'year', 'type': 'unsigned'}]
- null
...

Checking data distribution

To check how data is distributed across the replica sets, follow the steps below:

  1. Connect to any storage in the storage-a replica set:

    $ tt connect sharded_cluster_crud:storage-a-001
   • Connecting to the instance...
   • Connected to sharded_cluster_crud:storage-a-001

    Then, select all tuples in the bands space:

    sharded_cluster_crud:storage-a-001> box.space.bands:select()
---
- - [1, 477, 'Roxette', 1986]
  - [2, 401, 'Scorpions', 1965]
  - [4, 161, 'The Beatles', 1960]
  - [5, 172, 'Pink Floyd', 1965]
  - [6, 64, 'The Rolling Stones', 1962]
  - [8, 185, 'Nirvana', 1987]
...

  2. Connect to any storage in the storage-b replica set:

    $ tt connect sharded_cluster_crud:storage-b-001
   • Connecting to the instance...
   • Connected to sharded_cluster_crud:storage-b-001

    Select all tuples in the bands space to make sure it contains another subset of data:

    sharded_cluster_crud:storage-b-001> box.space.bands:select()
---
- - [3, 804, 'Ace of Base', 1987]
  - [7, 693, 'The Doors', 1965]
  - [9, 644, 'Led Zeppelin', 1968]
  - [10, 569, 'Queen', 1970]
  - [11, 652, 'The Who', 1962]
...

Getting started with Tarantool Cluster Manager

Enterprise Edition

This tutorial uses Tarantool Enterprise Edition.

Example on GitHub: tcm_get_started

In this tutorial, you get Tarantool Cluster Manager up and running on your local system, deploy a local Tarantool EE cluster, and learn to manage the cluster from the TCM web UI.

To complete this tutorial, you need:

For more detailed information about using TCM, refer to Tarantool Cluster Manager.

Setting up Tarantool EE

  1. Extract the Tarantool EE SDK archive:

    $ tar -xvzf tarantool-enterprise-sdk-gc64-<VERSION>-<HASH>-r<REVISION>.linux.x86_64.tar.gz

    This creates the tarantool-enterprise directory beside the archive. The directory contains three executables for key Tarantool EE components:

  2. Add the Tarantool EE components to the executable path by executing the env.sh script included in the distribution:

    $ source tarantool-enterprise/env.sh

  3. To check that the Tarantool EE executables tarantool, tt, and tcm are available in the system, print their versions:

    $ tarantool --version
Tarantool Enterprise 3.0.0-0-gf58f7d82a-r23-gc64
Target: Linux-x86_64-RelWithDebInfo
Build options: cmake . -DCMAKE_INSTALL_PREFIX=/home/centos/release/sdk/tarantool/static-build/tarantool-prefix -DENABLE_BACKTRACE=TRUE
Compiler: GNU-9.3.1
C_FLAGS: -fexceptions -funwind-tables -fasynchronous-unwind-tables -static-libstdc++ -fno-common -msse2  -fmacro-prefix-map=/home/centos/release/sdk/tarantool=. -std=c11 -Wall -Wextra -Wno-gnu-alignof-expression -fno-gnu89-inline -Wno-cast-function-type -O2 -g -DNDEBUG -ggdb -O2
CXX_FLAGS: -fexceptions -funwind-tables -fasynchronous-unwind-tables -static-libstdc++ -fno-common -msse2  -fmacro-prefix-map=/home/centos/release/sdk/tarantool=. -std=c++11 -Wall -Wextra -Wno-invalid-offsetof -Wno-gnu-alignof-expression -Wno-cast-function-type -O2 -g -DNDEBUG -ggdb -O2
$ tt version
Tarantool CLI EE 2.1.0, linux/amd64. commit: d80c2e3
$ tcm version
1.0.0-0-gd38b12c2

Starting TCM

Tarantool Cluster Manager is ready to run out of the box. To start TCM run the following command:

$ tcm --storage.etcd.embed.enabled

Важно

The TCM bootstrap log in the terminal includes a message with the credentials to use for the first login. Make sure to save them somewhere.

Jan 24 05:51:28.443 WRN Generated super admin credentials login=admin password=qF3A5rjGurjAwmlYccJ7JrL5XqjbIHY6

The –storage.etcd.embed.enabled option makes TCM start its own instance of etcd on bootstrap. This etcd instance is used for storing the TCM configuration.

Примечание

During the development, it is also convenient to use the TCM-embedded etcd as a configuration storage for Tarantool EE clusters connected to TCM. Learn more in Centralized configuration storages.

Logging into TCM

  1. Open a web browser and go to http://127.0.0.1:8080/.
  2. Enter the username and the password you got from the TCM bootstrap log in the previous step.
  3. Click Log in.

After a successful login, you see the TCM web UI:

TCM stateboard with empty cluster

Setting up a Tarantool EE cluster

To prepare a Tarantool EE cluster, complete the following steps:

  1. Define the cluster connection settings in TCM.
  2. Configure the cluster in TCM.
  3. Start the cluster instances locally using the tt utility.

Defining the cluster’s connection settings in TCM

A freshly installed TCM has a predefined cluster named Default cluster. It doesn’t have any configuration or topology out of the box. Its initial properties include the etcd and Tarantool connection parameters. Check these properties to find out where TCM sends the cluster configuration that you write.

To view the Default cluster’s properties:

  1. Go to Clusters and click Edit in the Actions menu opposite the cluster name.

    TCM edit cluster

  2. Click Next on the General tab.

    General cluster settings

  3. Find the connection properties of the configuration storage that the cluster uses. By default, it’s an etcd running on port 2379 (default etcd port) on the same host. The key prefix used for the cluster configuration is /default. Click Next.

    Cluster configuration storage settings

  4. Check the Tarantool user that TCM uses to connect to the cluster instances. It’s guest by default.

    Cluster Tarantool connection settings

Configuring a cluster in TCM

TCM provides a web-based editor for writing cluster configurations. It is connected to the configuration storage (etcd in this case): all changes you make in the browser are sent to etcd in one click.

To write the cluster configuration and upload it to the etcd storage:

  1. Go to Configuration.

  2. Click + and provide an arbitrary name for the configuration file, for example, all.

  3. Paste the following YAML configuration into the editor:

    credentials:
  users:
    guest:
      roles: [super]
groups:
  group-001:
    replicasets:
      replicaset-001:
        replication:
          failover: manual
        leader: instance-001
        instances:
          instance-001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
              advertise:
                client: '127.0.0.1:3301'
          instance-002:
            iproto:
              listen:
              - uri: '127.0.0.1:3302'
              advertise:
                client: '127.0.0.1:3302'
          instance-003:
            iproto:
              listen:
              - uri: '127.0.0.1:3303'
              advertise:
                client: '127.0.0.1:3303'

    This configuration sets up a cluster of three nodes in one replica set: one leader and two followers.

  4. Click Apply to send the configuration to etcd.

    Cluster configuration in TCM

When the cluster configuration is saved, you can see the cluster topology on the Stateboard page:

Offline cluster stateboard

However, the cluster instances are offline because they aren’t deployed yet.

Deploying the cluster locally

To deploy a local cluster based on the configuration from etcd:

  1. Go to the system terminal you used when setting up Tarantool.

  2. Create a new tt environment in a directory of your choice:

    $ mkdir cluster-env
$ cd cluster-env/
$ tt init

  3. Inside the instances.enabled directory of the created tt environment, create the cluster directory.

    $ mkdir instances.enabled/cluster
$ cd instances.enabled/cluster/

  4. Inside instances.enabled/cluster, create the instances.yml and config.yaml files:

    • instances.yml specifies instances to run in the current environment. In this example, there are three instances:

      instance-001:
instance-002:
instance-003:

    • config.yaml instructs tt to load the cluster configuration from etcd. The specified etcd location matches the configuration storage of the Default cluster in TCM:

      config:
  etcd:
    endpoints:
    - http://localhost:2379
    prefix: /default

  5. Start the cluster from the tt environment root (the cluster-env directory):

    $ tt start cluster

    To check how the cluster started, run tt status. This output should look like this:

    $ tt status cluster
INSTANCE                 STATUS      PID   MODE
cluster:instance-001     RUNNING     2058  RW
cluster:instance-002     RUNNING     2059  RO
cluster:instance-003     RUNNING     2060  RO

Managing the cluster in TCM

To learn to interact with a cluster in TCM, complete typical database tasks such as:

Checking cluster state

To check the cluster state in TCM, go to Stateboard. Here you see the overview of the cluster topology, health, memory consumption, and other information.

Online cluster stateboard

Connecting to an instance

To view detailed information about an instance, click its name in the instances list on the Stateboard page.

Instance details in TCM

To connect to the instance interactively and execute code on it, go to the Terminal tab.

Instance terminal in TCM

Creating a space

Go to the terminal of instance-001 (the leader instance) and run the following code to create a formatted space with a primary index in the cluster:

box.schema.space.create('bands')
box.space.bands:format({
    { name = 'id', type = 'unsigned' },
    { name = 'band_name', type = 'string' },
    { name = 'year', type = 'unsigned' }
})
box.space.bands:create_index('primary', { type = "tree", parts = { 'id' } })

Writing data

Since instance-001 is a read-write instance (its box.info.ro is false), the write requests must be executed on it. Run the following code in the instance-001 terminal to write tuples in the space:

box.space.bands:insert { 1, 'Roxette', 1986 }
box.space.bands:insert { 2, 'Scorpions', 1965 }
box.space.bands:insert { 3, 'Ace of Base', 1987 }

Reading data

Check the space’s tuples by running a read request on instance-001:

box.space.bands:select { 3 }

This is how it looks in TCM:

Writing data through TCM

Checking replication

To check that the data is replicated across instances, run the read request on any other instance – instance-002 or instance-003. The result is the same as on instance-001.

Reading data through TCM

Примечание

If you try to execute a write request on any instance but instance-001, you get an error because these instances are configured to be read-only.

Viewing data in TCM

TCM web UI includes a tool for viewing data stored in the cluster. To view the space tuples in TCM:

  1. Click an instance name on the Stateboard page.

  2. Open the Actions menu in the top-right corner and click Explorer.

    Opening Explorer in TCM

    This opens the page that lists user-created spaces on the instance.

    TCM Explorer: spaces

  3. Click View in the Actions menu of the space you want to see. The page shows all the tuples added previously.

    TCM Explorer: space tuples

Platform

This section contains documentation for the Tarantool platform consisting of a database and an application server.

Concepts

Storage engines

A storage engine is a set of low-level routines that store and retrieve values. Tarantool offers a choice of two storage engines:

For details, check the Storage engines section.

Data model

Tarantool is a NoSQL database. It stores data in spaces, which can be thought of as tables in a relational database, and tuples, which are analogous to rows. There are six basic data operations in Tarantool.

The platform allows describing the data schema but does not require it.

Tarantool supports highly customizable indexes of various types.

To ensure data persistence and recover quickly in case of failure, Tarantool uses mechanisms like the write-ahead log (WAL) and snapshots.

For details, check the Data model page.

Fibers and cooperative multitasking

Tarantool executes code in fibers that are managed via cooperative multitasking. Learn more about Tarantool’s thread model.

For details, check the page Fibers, yields, and cooperative multitasking.

Transactions

Tarantool’s ACID-compliant transaction model lets the user choose between two modes of transactions.

The default mode allows for fast monopolistic atomic transactions. It doesn’t support interactive transactions, and in case of an error, all transaction changes are rolled back.

The MVCC mode relies on a multi-version concurrency control engine that allows yielding within a longer transaction. This mode only works with the default in-memory memtx storage engine.

For details, check the Transactions page.

Replication

Replication allows keeping the data in copies of the same database for better reliability.

Several Tarantool instances can be organized in a replica set. They communicate and transfer data via the iproto binary protocol. Learn more about Tarantool’s replication architecture.

By default, replication in Tarantool is asynchronous. A transaction committed locally on the master node may not get replicated onto other instances before the client receives a success response. Thus, if the master reports success and then dies, the client might not see the result of the transaction.

With synchronous replication, transactions on the master node are not considered committed or successful before they are replicated onto a number of instances. This is slower, but more reliable. Synchronous replication in Tarantool is based on an implementation of the RAFT algorithm.

For details, check the Replication section.

Sharding

Tarantool implements database sharding via the vshard module. For details, go to the Sharding page.

Triggers

Tarantool allows specifying callback functions that run upon certain database events. They can be useful for resolving replication conflicts. For details, go to the Triggers page.

Application server

Using Tarantool as an application server, you can write applications in Lua, C, or C++. You can also create reusable modules.

To increase the speed of code execution, Tarantool has a Lua Just-In-Time compiler (LuaJIT) on board. LuaJIT compiles hot paths in the code – paths that are used many times – thus making the application work faster. To enable developers to work with LuaJIT, Tarantool provides tools like the memory profiler and the getmetrics module.

To learn how to use Tarantool as an application server, refer to the guides in the How-to section.

Движки базы данных

Движок базы данных — это набор низкоуровневых процессов, которые фактически хранят и получают значения кортежей. Tarantool предлагает выбор из двух движков базы данных:

Все подробности о том, как работают движки, вы можете найти в следующих разделах:

Хранение данных с помощью memtx

The memtx storage engine is used in Tarantool by default. The engine keeps all data in random-access memory (RAM), and therefore has a low read latency.

Tarantool prevents the data loss in case of emergency, such as outage or Tarantool instance failure, in the following ways:

In this section, the following topics are discussed in brief with the references to other sections that explain the subject matter in details.

Модель памяти

There is a fixed number of independent execution threads. The threads don’t share state. Instead they exchange data using low-overhead message queues. While this approach limits the number of cores that the instance uses, it removes competition for the memory bus and ensures peak scalability of memory access and network throughput.

Only one thread, namely, the transaction processor thread (further, TX thread) can access the database, and there is only one TX thread for each Tarantool instance. In this thread, transactions are executed in a strictly consecutive order. Multi-statement transactions exist to provide isolation: each transaction sees a consistent database state and commits all its changes atomically. At commit time, a yield happens and all transaction changes are written to WAL in a single batch. In case of errors during transaction execution, a transaction is rolled-back completely. Read more in the following sections: Transaction model, Transaction mode: MVCC.

Внутри потока TX есть область памяти, в которой Tarantool хранит данные. Эта область называется Arena.

../../../_images/arena2.svg

Data is stored in spaces. Spaces contain database records – tuples. To access and manipulate the data stored in spaces and tuples, Tarantool builds indexes.

Распределением памяти для спейсов, кортежей и индексов внутри области Arena управляют специальные аллокаторы. Для хранения кортежей главным образом используется аллокатор slab. В Tarantool встроен модуль под названием box.slab, предоставляющий статистику распределения slab. С помощью этой статистики можно отслеживать общее использование памяти и ее фрагментацию. Подробности см. в руководстве по модулю box.slab.

../../../_images/spaces_indexes.svg

Also inside the TX thread, there is an event loop. Within the event loop, there are a number of fibers. Fibers are cooperative primitives that allow interaction with spaces, that is, reading and writing the data. Fibers can interact with the event loop and between each other directly or by using special primitives called channels. Due to the usage of fibers and cooperative multitasking, the memtx engine is lock-free in typical situations.

../../../_images/fibers-channels.svg

To interact with external users, there is a separate network thread also called the iproto thread. The iproto thread receives a request from the network, parses and checks the statement, and transforms it into a special structure—a message containing an executable statement and its options. Then the iproto thread ships this message to the TX thread and runs the user’s request in a separate fiber.

../../../_images/iproto.svg

Персистентность данных

Tarantool ensures data persistence as follows:

../../../_images/wal.svg ../../../_images/snapshot03.svg

Таким образом, при перезапуске Tarantool данные можно полностью восстановить даже в аварийных ситуациях, например при отключении питания или падении экземпляра Tarantool, когда хранящаяся в оперативной памяти база данных утеряна.

Что происходит при перезапуске:

  1. Tarantool находит и читает последний файл снимка.
  2. Tarantool также находит и читает все файлы WAL, созданные после этого снимка.
  3. Как только снимок и файлы WAL будут прочитаны, набор данных в памяти будет полностью восстановлен. Он будет соответствовать состоянию экземпляра Tarantool на момент, когда тот прекратил работу.
  4. Во время чтения снимка и файлов WAL Tarantool строит первичные индексы.
  5. Когда все данные снова в памяти, Tarantool строит вторичные индексы.
  6. Tarantool запускает приложение.

Доступ к данным

Чтобы обращаться к данным, хранящимся в оперативной памяти, и работать с ними, Tarantool строит индексы, которые хранятся внутри области памяти Arena.

Tarantool поддерживает несколько типов индексов: TREE, HASH, BITSET, RTREE. Все они предназначены для разных сценариев использования.

Можно выполнять SELECT-запросы как по первичным, так и по вторичным ключам индекса. Ключи могут быть составными.

For detailed information about indexes, refer to the Индексы page.

Репликация данных

Хотя эта тема не имеет прямого отношения к движку memtx, она дополняет общую картину того, как работает Tarantool, когда приложение распределенное.

Репликация позволяет нескольким экземплярам Tarantool работать с копиями одной и той же базы данных. Эти копии остаются синхронизированными благодаря тому, что каждый экземпляр может сообщать другим экземплярам о совершенных им изменениях. Для этого используется WAL-репликация.

Чтобы отправить данные на реплику, Tarantool запускает еще один поток, называемый relay. Этот поток читает файлы WAL и отправляет их репликам. На каждой реплике выполняется файбер под названием applier. Он получает изменения от удаленного узла и применяет их к области Arena реплики. Все изменения записываются в файлы WAL через поток WAL реплики так же, как если бы они были сделаны локально.

../../../_images/replica-xlogs.svg

В Tarantool репликация по умолчанию асинхронна: то, что транзакция проходит коммит локально на главном узле, не означает, что она отправляется на какие-то другие реплики.

Эту проблему решает синхронная репликация. Каждая синхронная транзакция проходит коммит лишь после репликации на некотором количестве экземпляров, и только тогда клиенту приходит ответ о завершении транзакции.

Более подробные сведения вы найдете в главе о репликации.

Ключевые сведения

Вот главные принципы, по которым работает движок:

Хранение данных с помощью vinyl

Tarantool – это транзакционная, персистентная СУБД, которая хранит 100% данных в оперативной памяти. Основными преимущества хранения данных оперативной памяти являются скорость и простота использования: нет необходимости в оптимизации, однако производительность остается стабильно высокой.

Несколько лет назад мы решили расширить продукт путем реализации классической технологии хранения как в обычных СУБД: в оперативной памяти хранится лишь кэш данных, а основной объем данных находится на диске. Мы решили, что движок хранения можно будет выбирать независимо для каждой таблицы, как это реализовано в MySQL, но при этом с самого начала будет реализована поддержка транзакций.

Первый вопрос, на который нужен был ответ: создавать свой движок или использовать уже существующую библиотеку? Сообщество разработчиков открытого ПО предлагает готовые библиотеки на выбор. Активнее всего развивалась библиотека RocksDB, которая к настоящему времени стала одной из самых популярных. Есть также несколько менее известных библиотек: WiredTiger, ForestDB, NestDB, LMDB.

Тем не менее, изучив исходный код существующих библиотек и взвесив все «за» и «против», мы решили написать свой движок. Одна из причин – все существующие сторонние библиотеки предполагают, что запросы к данным могут поступать из множества потоков операционной системы, и поэтому содержат сложные примитивы синхронизации для управления одновременным доступом к данным. Если бы мы решили встраивать одну из них в Tarantool, то пользователи были бы вынуждены нести издержки многопоточных приложений, не получая ничего взамен. Дело в том, что в основе Tarantool лежит архитектура на основе акторов. Обработка транзакций в выделенном потоке позволяет обойтись без лишних блокировок, межпроцессного взаимодействия и других затрат ресурсов, которые забирают до 80% процессорного времени в многопоточных СУБД.

../../../_images/actor_threads.png

Процесс в Tarantool состоит из заданного количества потоков

Если изначально проектировать движок с учетом кооперативной многозадачности, можно не только существенно ускорить работу, но и реализовать приемы оптимизации, слишком сложные для многопоточных движков. В общем, использование стороннего решения не привело бы к лучшему результату.

Алгоритм

Отказавшись от идеи внедрения существующих библиотек, необходимо было выбрать архитектуру для использования в качестве основы. Есть два альтернативных подхода к хранению данных на диске: старая модель с использованием B-деревьев и их разновидностей и новая – на основе журнально-структурированных деревьев со слиянием, или LSM-деревьев (Log Structured Merge Tree). MySQL, PostgreSQL и Oracle используют B-деревья, а Cassandra, MongoDB и CockroachDB уже используют LSM-деревья.

Считается, что B-деревья более эффективны для чтения, а LSM-деревья – для записи. Тем не менее, с распространением SSD-дисков, у которых в несколько раз выше производительность чтения по сравнению с производительностью записи, преимущества LSM-деревьев стали очевидны в большинстве сценариев.

Прежде чем разбираться с LSM-деревьями в Tarantool, посмотрим, как они работают. Для этого разберем устройство обычного B-дерева и связанные с ним проблемы. «B» в слове B-tree означает «Block», то есть это сбалансированное дерево, состоящее из блоков, которые содержат отсортированные списки пар ключ-значение. Вопросы наполнения дерева, балансировки, разбиения и слияния блоков выходят за рамки данной статьи, подробности вы сможете прочитать в Википедии. В итоге мы получаем отсортированный по возрастанию ключа контейнер, минимальный элемент которого хранится в крайнем левом узле, а максимальный – в крайнем правом. Посмотрим, как в B-дереве осуществляется поиск и вставка данных.

../../../_images/classical_b_tree.png

Классическое B-дерево

Если необходимо найти элемент или проверить его наличие, поиск начинается, как обычно, с вершины. Если ключ обнаружен в корневом блоке, поиск заканчивается; в противном случае, переходим в блок с наибольшим меньшим ключом, то есть в самый правый блок, в котором еще есть элементы меньше искомого (элементы на всех уровнях расположены по возрастанию). Если и там элемент не найден, снова переходим на уровень ниже. В конце концов окажемся в одном из листьев и, возможно, обнаружим искомый элемент. Блоки дерева хранятся на диске и читаются в оперативную память по одному, то есть в рамках одного поиска алгоритм считывает logB(N) блоков, где N – это количество элементов в B-дереве. Запись в самом простом случае осуществляется аналогично: алгоритм находит блок, который содержит необходимый элемент, и обновляет (вставляет) его значение.

Чтобы наглядно представить себе эту структуру данных, возьмем B-дерево на 100 000 000 узлов и предположим, что размер блока равен 4096 байтов, а размер элемента – 100 байтов. Таким образом, в каждом блоке можно будет разместить до 40 элементов с учетом накладных расходов, а в B-дереве будет около 2 570 000 блоков, пять уровней, при этом первые четыре займут по 256 МБ, а последний – до 10 ГБ. Очевидно, что на любом современном компьютере все уровни, кроме последнего, успешно попадут в кэш файловой системы, и фактически любая операция чтения будет требовать не более одной операции ввода-вывода.

Ситуация выглядит существенно менее радужно при смене точки зрения. Предположим, что необходимо обновить один элемент дерева. Так как операции с B-деревьями работают через чтение и запись целых блоков, приходится прочитать 1 блок в память, изменить 100 байт из 4096, а затем записать обновленный блок на диск. Таким образом, нам пришлось записать в 40 раз больше, чем реальный объем измененных данных!

Принимая во внимание, что внутренний размер блока в SSD-дисках может быть 64 КБ и больше, и не любое изменение элемента меняет его целиком, объем «паразитной» нагрузки на диск может быть еще выше.

Феномен таких «паразитных» чтений в литературе и блогах, посвященных хранению на диске, называется read amplification (усложнение чтения), а феномен «паразитной» записи – write amplification (усложнение записи).

Коэффициент усложнения, то есть коэффициент умножения, вычисляется как отношение размера фактически прочитанных (или записанных) данных к реально необходимому (или измененному) размеру. В нашем примере с B-деревом коэффициент составит около 40 как для чтения, так и для записи.

Объем «паразитных» операций ввода-вывода при обновлении данных является одной из основных проблем, которую решают LSM-деревья. Рассмотрим, как это работает.

Ключевое отличие LSM-деревьев от классических B-деревьев заключается в том, что LSM-деревья не просто хранят данные (ключи и значения), а также операции с данными: вставки и удаления.

../../../_images/lsm.png


LSM-дерево:

Например, элемент для операции вставки, помимо ключа и значения, содержит дополнительный байт с кодом операции – обозначенный выше как REPLACE. Элемент для операции удаления содержит ключ элемента (хранить значение нет необходимости) и соответствующий код операции – DELETE. Также каждый элемент LSM-дерева содержит порядковый номер операции (log sequence number – LSN), то есть значение монотонно возрастающей последовательности, которое уникально идентифицирует каждую операцию. Таким образом, всё дерево упорядочено сначала по возрастанию ключа, а в пределах одного ключа – по убыванию LSN.

../../../_images/lsm_single.png

Один уровень LSM-дерева

Наполнение LSM-дерева

В отличие от B-дерева, которое полностью хранится на диске и может частично кэшироваться в оперативной памяти, в LSM-дереве разделение между памятью и диском явно присутствует с самого начала. При этом проблема сохранности данных, расположенных в энергозависимой памяти, выносится за рамки алгоритма хранения: ее можно решить разными способами, например, журналированием изменений.

Часть дерева, расположенную в оперативной памяти, называют L0 (level zero – уровень ноль). Объем оперативной памяти ограничен, поэтому для L0 отводится фиксированная область. В конфигурации Tarantool, например, размер L0 задается с помощью параметра vinyl_memory. В начале, когда LSM-дерево не содержит элементов, операции записываются в L0. Следует отметить, что элементы в дереве упорядочены по возрастанию ключа, а затем по убыванию LSN, так что в случае вставки нового значения по данному ключу легко обнаружить и удалить предыдущее значение. L0 может быть представлен любым контейнером, который сохраняет упорядоченность элементов. Например, для хранения L0 Tarantool использует B+*-дерево. Операции поиска и вставки – это стандартные операции структуры данных, используемой для представления L0, и мы их подробно рассматривать не будем.

Рано или поздно количество элементов в дереве превысит размер L0. Тогда L0 записывается в файл на диске (который называется забегом – «run») и освобождается под новые элементы. Эта операция называется «дамп» (dump).

../../../_images/dumps.png


Все дампы на диске образуют последовательность, упорядоченную по LSN: диапазоны LSN в файлах не пересекаются, а ближе к началу последовательности находятся файлы с более новыми операциями. Представим эти файлы в виде пирамиды, где новые файлы расположены вверху, а старые внизу. По мере появления новых файлов забегов, высота пирамиды растет. При этом более свежие файлы могут содержать операции удаления или замены для существующих ключей. Для удаления старых данных необходимо производиться сборку мусора (этот процесс иногда называется «слияние» – в английском языке «merge» или «compaction»), объединяя нескольких старых файлов в новый. Если при слиянии мы встречаем две версии одного и того же ключа, то достаточно оставить только более новую версию, а если после вставки ключа он был удален, то из результата можно исключить обе операции.

../../../_images/purge.png


Ключевым фактором эффективности LSM-дерева является то, в какой момент и для каких файлов делается слияние. Представим, что LSM-дерево в качестве ключей хранит монотонную последовательность вида 1, 2, 3 …, и операций удаления нет. В этом случае слияние будет бесполезным – все элементы уже отсортированы, дерево не содержит мусор и можно однозначно определить, в каком файле находится каждый ключ. Напротив, если LSM-дерево содержит много операций удаления, слияние позволит освободить место на диске. Но даже если удалений нет, а диапазоны ключей в разных файлах сильно пересекаются, слияние может ускорить поиск, так как сократит число просматриваемых файлов. В этом случае имеет смысл выполнять слияние после каждого дампа. Однако следует отметить, что такое слияние приведет к перезаписи всех данных на диске, поэтому если чтений мало, то лучше делать слияния реже.

Для оптимальной конфигурации под любой из описанных выше сценариев в LSM-дереве все файлы организованы в пирамиду: чем новее операции с данными, тем выше они находятся в пирамиде. При этом в слиянии участвуют два или несколько соседних файлов в пирамиде; по возможности выбираются файлы примерно одинакового размера.

../../../_images/compaction.png


  • Многоуровневое слияние может охватить любое количество уровней
  • Уровень может содержать несколько файлов

Все соседние файлы примерно одинакового размера составляют уровень LSM-дерева на диске. Соотношение размеров файлов на различных уровнях определяет пропорции пирамиды, что позволяет оптимизировать дерево под интенсивные вставки, либо интенсивные чтения.

Предположим, что размер L0 составляет 100 МБ, а соотношение размеров файлов на каждом уровне (параметр vinyl_run_size_ratio) равно 5, и на каждом уровне может быть не более 2 файлов (параметр vinyl_run_count_per_level). После первых трех дампов на диске появятся 3 файла по 100 МБ, эти файлы образуют уровень L1. Так как 3 > 2, запустится слияние файлов в новый файл размером 300 МБ, а старые будут удалены. Спустя еще 2 дампа снова запустится слияние, на этот раз файлов в 100, 100 и 300 МБ, в результате файл размером 500 МБ переместится на уровень L2 (вспомним, что соотношение размеров уровней равно 5), а уровень L1 останется пустым. Пройдут еще 10 дампов, и получим 3 файла по 500 МБ на уровне L2, в результате чего будет создан один файл размером 1500 МБ. Спустя еще 10 дампов произойдет следующее: 2 раза произведем слияние 3 файлов по 100 МБ, а также 2 раза слияние файлов по 100, 100 и 300 МБ, что приведет к созданию двух файлов на уровне L2 по 500 МБ. Поскольку на уровне L2 уже есть три файла, запустится слияние двух файлов по 500 МБ и одного файла в 1500 МБ. Полученный в результате файл в 2500 МБ, в силу своего размера, переедет на уровень L3.

Процесс может продолжаться до бесконечности, а если в потоке операций с LSM-деревом будет много удалений, образовавшийся в результате слияния файл может переместиться не только вниз по пирамиде, но и вверх, так как окажется меньше исходных файлов, использовавшихся при слиянии. Иными словами, принадлежность файла к уровню достаточно отслеживать логически на основе размера файла и минимального и максимального LSN среди всех хранящихся в нем операций.

Управление формой LSM-дерева

Если число файлов для поиска нужно уменьшить, то соотношение размеров файлов на разных уровнях можно увеличить, и, как следствие, уменьшается число уровней. Если, напротив, необходимо снизить затраты ресурсов, вызванные слиянием, то можно уменьшить соотношение размеров уровней: пирамида будет более высокой, а слияние хотя и выполняется чаще, но работает в среднем с файлами меньшего размера, за счет чего суммарно выполняет меньше работы. В целом, «паразитная запись» в LSM-дереве описывается формулой log_{x}(\\frac {N} {L0}) × x или x × \\frac {ln (\\frac {N} {C0})} {ln(x)}, где N – это общий размер всех элементов дерева, L0 – это размер уровня ноль, а x – это соотношение размеров уровней (параметр level_size_ratio). Если \\frac {N} {C0} = 40 (соотношение диск-память), график выглядит примерно вот так:

../../../_images/curve.png


«Паразитное» чтение при этом пропорционально количеству уровней. Стоимость поиска на каждом уровне не превышает стоимости поиска в B-дереве. Возвращаясь к нашему примеру дерева в 100 000 000 элементов: при наличии 256 МБ оперативной памяти и стандартных значений параметров vinyl_run_size_ratio и vinyl_run_count_per_level, получим коэффициент «паразитной» записи равным примерно 13, коэффициент «паразитной» записи может доходить до 150. Разберемся, почему это происходит.

Поиск по диапазону

Если при поиске по одному ключу алгоритм завершается после первого совпадения, то для поиска всех значений в диапазоне (например, всех пользователей с фамилией «Иванов») необходимо просматривать все уровни дерева.

../../../_images/range_search.png

Поиск по диапазону [24,30)

Формирование искомого диапазона при этом происходит так же, как и при слиянии нескольких файлов: из всех источников алгоритм выбирает ключ с максимальным LSN, отбрасывает остальные операции по этому ключу, сдвигает позицию поиска на следующий ключ и повторяет процедуру.

Удаление

Зачем вообще хранить операции удаления? И почему это не приводит к переполнению дерева, например, в сценарии for i=1,10000000 put(i) delete(i) end?

Роль операций удаления при поиске – сообщать об отсутствии искомого значения, а при слиянии – очищать дерево от «мусорных» записей с более старыми LSN.

Пока данные хранятся только в оперативной памяти, нет необходимости хранить операции удаления. Также нет необходимости сохранять операции удаления после слияния, если оно затрагивает в том числе самый нижний уровень дерева – на нем находятся данные самого старого дампа. Действительно, отсутствие значения на последнем уровне означает, что оно отсутствует в дереве.

  • Нельзя производить удаление из файлов, которые обновляются только путем присоединения новых записей
  • Вместо этого на уровень L0 вносятся маркеры удаленных записей (tombstones)
../../../_images/deletion_1.png

Удаление, шаг 1: вставка удаленной записи в L0

../../../_images/deletion_2.png

Удаление, шаг 2: удаленная запись проходит через промежуточные уровни

../../../_images/deletion_3.png

Удаление, шаг 3: при значительном слиянии удаленная запись удаляется из дерева

Если мы знаем, что удаление следует сразу за вставкой уникального значения – а это частый случай при изменении значения во вторичном индексе – то операцию удаления можно отфильтровывать уже при слиянии промежуточных уровней. Эта оптимизация реализована в vinyl’е.

Преимущества LSM-дерева

Помимо снижения «паразитной» записи, подход с периодическими дампами уровня L0 и слиянием уровней L1-Lk имеет ряд преимуществ перед подходом к записи, используемым в B-деревьях:

Недостатки LSM-дерева и их устранение

Одним из ключевых преимуществ B-дерева как структуры данных для поиска является предсказуемость: любая операция занимает не более чем log_{B}(N). В классическом LSM-дереве скорость как чтения, так и записи могут может отличаться в лучшем и худшем случае в сотни и тысячи раз. Например, добавление всего лишь одного элемента в L0 может привести к его переполнению, что в свою очередь, может привести к переполнению L1, L2 и т.д. Процесс чтения может обнаружить исходный элемент в L0, а может задействовать все уровни. Чтение в пределах одного уровня также необходимо оптимизировать, чтобы добиться скорости, сравнимой с B-деревом. К счастью, многие недостатки можно скрасить или полностью устранить с помощью вспомогательных алгоритмов и структур данных. Систематизируем эти недостатки и опишем способы борьбы с ними, используемые в Tarantool.

Непредсказуемая скорость записи

Вставка данных в LSM-дерево почти всегда задействует исключительно L0. Как избежать простоя, если заполнена область оперативной памяти, отведенная под L0?

Освобождение L0 подразумевает две долгих операции: запись на диск и освобождение памяти. Чтобы избежать простоя во время записи L0 на диск, Tarantool использует упреждающую запись. Допустим, размер L0 составляет 256 MБ. Скорость записи на диск составляет 10 МБ/с. Тогда для записи L0 на диск понадобится 26 секунд. Скорость вставки данных составляет 10 000 запросов в секунду, а размер одного ключа – 100 байтов. На время записи необходимо зарезервировать около 26 MБ доступной оперативной памяти, сократив реальный полезный размер L0 до 230 MБ.

Tarantool does all of these calculations automatically, constantly updating the rolling average of the DBMS workload and the histogram of the disk speed. This allows using L0 as efficiently as possible and it prevents write requests from timing out. But in the case of workload surges, some wait time is still possible. That’s why we also introduced an insertion timeout (the vinyl_timeout parameter), which is set to 60 seconds by default. The write operation itself is executed in dedicated threads. The number of these threads (4 by default) is controlled by the vinyl_write_threads parameter. The default value of 2 allows doing dumps and compactions in parallel, which is also necessary for ensuring system predictability.

Слияния в Tarantool всегда выполняются независимо от дампов, в отдельном потоке выполнения. Это возможно благодаря природе LSM-дерева – после записи файлы в дереве никогда не меняются, а слияние лишь создает новый файл.

К задержкам также может приводить ротация L0 и освобождение памяти, записанной на диск: в процессе записи памятью L0 владеют два потока операционной системы – поток обработки транзакций и поток записи. Хотя в L0 во время ротации элементы не добавляются, он может участвовать в поиске. Чтобы избежать блокировок на чтение во время поиска, поток записи не освобождает записанную память, а оставляет эту задачу потоку обработки транзакций. Само освобождение после завершения дампа происходит мгновенно: для этого в L0 используется специализированный механизм распределения, позволяющий освободить всю память за одну операцию.

../../../_images/dump_from_shadow.png
  • упреждающий дамп
  • загрузка

Дамп происходит из так называемого «теневого» L0, не блокируя новые вставки и чтения

Непредсказуемая скорость чтений

Чтение – самая сложная задача для оптимизации в LSM-деревьях. Главным фактором сложности является большое количество уровней: это не только значительно замедляет поиск, но и потенциально значительно увеличивает требования к оперативной памяти при почти любых попытках оптимизации. К счастью, природа LSM-деревьев, где файлы обновляются только путем присоединения новых записей, позволяет решать эти проблемы нестандартными для традиционных структур данных способами.

../../../_images/read_speed.png
  • постраничный индекс
  • фильтры Блума
  • кэш диапазона кортежей
  • многоуровневое слияние

Сжатие и постраничный индекс

Сжатие данных в B-деревьях – это либо сложнейшая в реализации задача, либо больше средство маркетинга, чем действительно полезный инструмент. Сжатие в LSM-деревьях работает следующим образом:

При любом дампе или слиянии мы разбиваем все данные в одном файле на страницы. Размер страницы в байтах задается в параметре vinyl_page_size, который можно менять отдельно для каждого индекса. Страница не обязана занимать строго то количество байт, которое прописано vinyl_page_size – она может быть чуть больше или чуть меньше, в зависимости от хранящихся в ней данных. Благодаря этому страница никогда не содержит пустот.

Для сжатия используется потоковый алгоритм Facebook под названием «zstd». Первый ключ каждой страницы и смещение страницы в файле добавляются в так называемый постраничный индекс (page index) – отдельный файл, который позволяет быстро найти нужную страницу. После дампа или слияния постраничный индекс созданного файла также записывается на диск.

Все файлы типа .index кэшируются в оперативной памяти, что позволяет найти нужную страницу за одно чтение из файла .run (такое расширение имени файла используется в vinyl’е для файлов, полученных в результате дампа или слияния). Поскольку данные в странице отсортированы, после чтения и декомпрессии нужный ключ можно найти с помощью простого бинарного поиска. За чтение и декомпрессию отвечают отдельные потоки, их количество определяется в параметре vinyl_read_threads.

Tarantool использует единый формат файлов: например, формат данных в файле .run ничем не отличается от формата файла .xlog (файл журнала). Это упрощает резервное копирование и восстановление, а также работу внешних инструментов.

Фильтры Блума

Хотя постраничный индекс позволяет уменьшить количество страниц, просматриваемых при поиске в одном файле, он не отменяет необходимости искать на всех уровнях дерева. Есть важный частный случай, когда необходимо проверить отсутствие данных, и тогда просмотр всех уровней неизбежен: вставка в уникальный индекс. Если данные уже существуют, то вставка в уникальный индекс должна завершиться с ошибкой. Единственный способ вернуть ошибку до завершения транзакции в LSM-дереве – произвести поиск перед вставкой. Такого рода чтения в СУБД образуют целый класс, называемый «скрытыми» или «паразитными» чтениями.

Другая операция, приводящая к скрытым чтениям, – обновление значения, по которому построен вторичный индекс. Вторичные ключи представляют собой обычные LSM-деревья, в которых данные хранятся в другом порядке. Чаще всего, чтобы не хранить все данные во всех индексах, значение, соответствующее данному ключу, целиком сохраняется только в первичном индексе (любой индекс, хранящий и ключ, и значение, называется покрывающим или кластерным), а во вторичном индексе сохраняются лишь поля, по которым построен вторичный индекс, и значения полей, участвующих в первичном индексе. Тогда при любом изменении значения, по которому построен вторичный ключ, приходится сначала удалять из вторичного индекса старый ключ, и только потом вставлять новый. Старое значение во время обновления неизвестно – именно его и нужно читать из первичного ключа с точки зрения внутреннего устройства.

Например:

update t1 set city=’Moscow’ where id=1

Чтобы уменьшить количество чтений с диска, особенно для несуществующих значений, практически все LSM-деревья используют вероятностные структуры данных. Tarantool не исключение. Классический фильтр Блума – это набор из нескольких (обычно 3-5) битовых массивов. При записи для каждого ключа вычисляется несколько хеш-функций, и в каждом массиве выставляется бит, соответствующий значению хеша. При хешировании могут возникнуть коллизии, поэтому некоторые биты могут быть проставлены дважды. Интерес представляют биты, которые оказались не проставлены после записи всех ключей. При поиске также вычисляются выбранные хеш-функции. Если хотя бы в одном из битовых массивов бит не стоит, то значение в файле отсутствует. Вероятность срабатывания фильтра Блума определяется теоремой Байеса: каждая хеш-функция представляет собой независимую случайную величину, благодаря чему вероятность того, что во всех битовых массивах одновременно произойдет коллизия, очень мала.

Ключевым преимуществом реализации фильтров Блума в Tarantool является простота настройки. Единственный параметр, который можно менять независимо для каждого индекса, называется vinyl_bloom_fpr (FPR в данном случае означает сокращение от «false positive ratio» – коэффициент ложноположительного срабатывания), который по умолчанию равен 0,05, или 5%. На основе этого параметра Tarantool автоматически строит фильтры Блума оптимального размера для поиска как по полному ключу, так и по компонентам ключа. Сами фильтры Блума хранятся вместе с постраничным индексом в файле .index и кэшируются в оперативной памяти.

Кэширование

Многие привыкли считать кэширование панацеей от всех проблем с производительностью: «В любой непонятной ситуации добавляй кэш». В vinyl’е мы смотрим на кэш скорее как на средство снижения общей нагрузки на диск, и, как следствие, получения более предсказуемого времени ответов на запросы, которые не попали в кэш. В vinyl’е реализован уникальный для транзакционных систем вид кэша под названием «кэш диапазона кортежей» (range tuple cache). В отличие от RocksDB, например, или MySQL, этот кэш хранит не страницы, а уже готовые диапазоны значений индекса, после их чтения с диска и слияния всех уровней. Это позволяет использовать кэш для запросов как по одному ключу, так и по диапазону ключей. Поскольку в кэше хранятся только горячие данные, а не, скажем, страницы (в странице может быть востребована лишь часть данных), оперативная память используется наиболее оптимально. Размер кэша задается в параметре vinyl_cache.

Управление сборкой мусора

Возможно, добравшись до этого места вы уже начали терять концентрацию и нуждаетесь в заслуженной дозе допамина. Самое время сделать перерыв, так как для того, чтобы разобраться с оставшейся частью, понадобятся серьезные усилия.

В vinyl’е устройство одного LSM-дерева – это лишь фрагмент мозаики. Vinyl создает и обслуживает несколько LSM-деревьев даже для одной таблицы (так называемого спейса) – по одному дереву на каждый индекс. Но даже один единственный индекс может состоять из десятков LSM-деревьев. Попробуем разобраться, зачем.

Рассмотрим наш стандартный пример: 100 000 000 записей по 100 байтов каждая. Через некоторое время на самом нижнем уровне LSM у нас может оказаться файл размером 10 ГБ. Во время слияния последнего уровня мы создадим временный файл, который также будет занимать около 10 ГБ. Данные на промежуточных уровнях тоже занимают место: по одному и тому же ключу дерево может хранить несколько операций. Суммарно для хранения 10 ГБ полезных данных нам может потребоваться до 30 ГБ свободного места: 10 ГБ на последний уровень, 10 ГБ на временный файл и 10 ГБ на всё остальное. А если данных не 1 ГБ, а 1 ТБ? Требовать, чтобы количество свободного места на диске всегда в несколько раз превышало объем полезных данных, экономически нецелесообразно, да и создание файла в 1ТБ может занимать десятки часов. При любой аварии или перезапуске системы операцию придется начинать заново.

Рассмотрим другую проблему. Представим, что первичный ключ дерева – это монотонная последовательность, например, временной ряд. В этом случае основные вставки будут приходиться на правую часть диапазона ключей. Нет смысла заново производить слияние лишь для того, чтобы дописать в конец и без того огромного файла еще несколько миллионов записей.

А если вставки происходят, в основном, в одну часть диапазона ключей, а чтения – из другой части? Как в этом случае оптимизировать форму дерева? Если оно будет слишком высоким, пострадают чтения, если слишком низким – запись.

Tarantool «факторизует» проблему, создавая не одно, а множество LSM-деревьев для каждого индекса. Примерный размер каждого поддерева можно задать в конфигурационном параметре vinyl_range_size. Такие поддеревья называется диапазонами («range»).

../../../_images/factor_lsm.png


Факторизация больших LSM-деревьев с помощью диапазонов

  • Диапазоны отражают статичную структуру упорядоченных файлов
  • Срезы объединяют упорядоченный файл в диапазон

Изначально, пока в индексе мало элементов, он состоит из одного диапазона. По мере добавления элементов суммарный объем может превысить максимальный размер диапазона. В таком случае выполняется операция под названием «разделение» (split), которая делит дерево на две равные части. Разделение происходит по срединному элементу диапазона ключей, хранящихся в дереве. Например, если изначально дерево хранит полный диапазон -inf… +inf, то после разделения по срединному ключу X получим два поддерева: одно будет хранить все ключи от -inf до X, другое – от X до +inf. Таким образом, при вставке или чтении мы однозначно знаем, к какому поддереву обращаться. Если в дереве были удаления и каждый из соседних диапазонов уменьшился, выполняется обратная операция под названием «объединение» (coalesce). Она объединяет два соседних дерева в одно.

Разделение и объединение не приводят к слиянию, созданию новых файлов и прочим тяжеловесным операциям. LSM-дерево – это лишь набор файлов. В vinyl’е мы реализовали специальный журнал метаданных, позволяющий легко отслеживать, какой файл принадлежит какому поддереву или поддеревьям. Журнал имеет расширение .vylog, по формату он совместим с файлом .xlog. Как и файл .xlog, происходит автоматическая ротация файла при каждой контрольной точке. Чтобы избежать повторного создания файлов при разделении и объединении, мы ввели промежуточную сущность – срез (slice). Это ссылка на файл с указанием диапазона значений ключа, которая хранится исключительно в журнале метаданных. Когда число ссылок на файл становится равным нулю, файл удаляется. А когда необходимо произвести разделение или объединение, Tarantool создает срезы для каждого нового дерева, старые срезы удаляет, и записывает эти операции в журнал метаданных. Буквально, журнал метаданных хранит записи вида <идентификатор дерева, идентификатор среза> или <идентификатор среза, идентификатор файла, мин, макс>.

Таким образом, непосредственно тяжелая работа по разбиению дерева на два поддерева, откладывается до слияния и выполняется автоматически. Огромным преимуществом подхода с разделением всего диапазона ключей на диапазоны является возможность независимо управлять размером L0, а также процессом создания дампов и слиянием для каждого поддерева. В результате эти процессы являются управляемыми и предсказуемыми. Наличие отдельного журнала метаданных также упрощает выполнение таких операций, как усечение и удаление – в vinyl’е они обрабатываются мгновенно, потому что работают исключительно с журналом метаданных, а удаление мусора выполняется в фоне.

Расширенные возможности vinyl’а

Upsert (обновление и вставка)

В предыдущих разделах упоминались лишь две операции, которые хранит LSM-дерево: удаление и замена. Давайте рассмотрим, как представлены все остальные. Вставку можно представить с помощью замены – необходимо лишь предварительно убедиться в отсутствии элемента указанным ключом. Для выполнения обновления необходимо предварительно считывать старое значение из дерева, так что и эту операцию проще записать в дерево как замену – это ускорит будущие чтения по этому ключу. Кроме того, обновление должно вернуть новое значение, так что скрытых чтений никак не избежать.

В B-деревьях скрытые чтения почти ничего не стоят: чтобы обновить блок, его в любом случае необходимо прочитать с диска. Для LSM-деревьев идея создания специальной операции обновления, которая не приводила бы к скрытым чтениям, выглядит очень заманчивой.

Такая операция должна содержать как значение по умолчанию, которое нужно вставить, если данных по ключу еще нет, так и список операций обновления, которые нужно выполнить, если значение существует.

На этапе выполнения транзакции Tarantool лишь сохраняет всю операцию в LSM-дереве, а «выполняет» ее уже только во время слияния.

Операция обновления и вставки:

space:upsert(tuple, {{operator, field, value}, ... })
  • Обновление без чтения или вставка
  • Отложенное выполнение
  • Фоновое сжатие операций обновления и вставки предотвращает накапливание операций

К сожалению, если откладывать выполнение операции на этап слияния, возможностей для обработки ошибок не остается. Поэтому Tarantool стремится максимально проверять операции обновления и вставки upsert перед записью в дерево. Тем не менее, некоторые проверки можно выполнить лишь имея старые данные на руках. Например, если обновление прибавляет число к строке или удаляет несуществующее поле.

Операция с похожей семантикой присутствует во многих продуктах, в том числе в PostgreSQL и MongoDB. Но везде она представляет собой лишь синтаксический сахар, объединяющий обновление и вставку, не избавляя СУБД от необходимости выполнять скрытые чтения. Скорее всего, причиной этого является относительная новизна LSM-деревьев в качестве структур данных для хранения.

Хотя обновление и вставка upsert представляет собой очень важную оптимизацию, и ее реализация стоила нам долгой напряженной работы, следует признать, что ее применимость ограничена. Если в таблице есть вторичные ключи или триггеры, скрытых чтений не избежать. А если у вас есть сценарии, для которых не нужны вторичные ключи и обновление после завершения транзакции однозначно не приведет к ошибкам – эта операция для вас.

Небольшая история, связанная с этим оператором: vinyl только начинал «взрослеть», и мы впервые запустили операцию обновления и вставки upsert на рабочие серверы. Казалось бы, идеальные условия: огромный набор ключей, текущее время в качестве значения, операции обновления либо вставляют ключ, либо обновляют текущее время, редкие операции чтения. Нагрузочные тесты показали отличные результаты.

Тем не менее, после пары дней работы процесс Tarantool начал потреблять 100 % CPU, а производительность системы упала практически до нуля.

Начали подробно изучать проблему. Оказалось, что распределение запросов по ключам существенно отличалось от того, что мы видели в тестовом окружении. Оно было… очень неравномерное. Большая часть ключей обновлялась 1-2 раза за сутки, и база для них не была нагружена. Но были ключи гораздо более горячие – десятки тысяч обновлений в сутки. Tarantool прекрасно справлялся с этим потоком обновлений. А вот когда по ключу с десятком тысяч операций обновления и вставки upsert происходило чтение, всё шло под откос. Чтобы вернуть последнее значение, Tarantool приходилось каждый раз прочитать и «проиграть» историю из десятков тысяч команд обновления и вставки upsert. На стадии проекта мы надеялись, что это произойдет автоматически во время слияния уровней, но до слияния дело даже не доходило: памяти L0 было предостаточно, и дампы не создавались.

Решили мы проблему добавлением фонового процесса, осуществляющего упреждающие чтения для ключей, по которым накопилось больше нескольких десятков операций обновления и вставки upsert с последующей заменой на прочитанное значение.

Вторичные ключи

Не только для операции обновления остро стоит проблема оптимизации скрытых чтений. Даже операция замены при наличии вторичных ключей вынуждена читать старое значение: его нужно независимо удалить из вторичных индексов, а вставка нового элемента может этого не сделать, оставив в индексе мусор.

../../../_images/secondary.png


Если вторичные индексы не уникальны, то удаление из них «мусора» также можно перенести в фазу слияния, что мы и делаем в Tarantool. Природа LSM-дерева, в котором файлы обновляются путем присоединения новых записей, позволила нам реализовать в vinyl’е полноценные сериализуемые транзакции. Запросы только для чтения при этом используют старые версии данных и не блокируют запись. Сам менеджер транзакций пока довольно простой: в традиционной классификации он реализует класс MVTO (multiversion timestamp ordering – упорядочение временных меток на основе многоверсионности), при этом в конфликте побеждает та транзакция, что завершилась первой. Блокировок и свойственных им взаимоблокировок нет. Как ни странно, это скорее недостаток, чем преимущество: при параллельном выполнении можно повысить количество успешных транзакций, задерживая некоторые из них в нужный момент на блокировке. Развитие менеджера транзакций в наших ближайших планах. В текущей версии мы сфокусировались на том, чтобы сделать алгоритм корректным и предсказуемым на 100%. Например, наш менеджер транзакций – один из немногих в NoSQL-среде, поддерживающих так называемые «блокировки разрывов» (gap locks).

Различие между движками memtx и vinyl

Основное различие между движками memtx и vinyl в том, что memtx — in-memory движок, тогда как vinyl — это дисковый движок. Обычно in-memory движок быстрее: время выполнения запроса, как правило, менее 1 мс. Поэтому движок memtx используется в Tarantool по умолчанию. Однако если база данных не помещается в доступную память, а дополнительную память добавить невозможно, то лучше использовать дисковый движок, в данном случае vinyl.

Характеристика memtx vinyl
Поддерживаемый тип индекса TREE, HASH, RTREE или BITSET TREE
Временные спейсы Поддерживается Не поддерживается
функция random() Поддерживается Не поддерживается
функция alter() Поддерживается Поддерживается с версии 1.10.2 (первичный индекс изменять нельзя)
функция len() Возвращает количество кортежей в спейсе Возвращает максимальное примерное количество кортежей в спейсе
функция count() Занимает одинаковые периоды времени Занимает различное количество времени в зависимости от состояния БД
функция delete() Возвращает удаленный кортеж, если есть таковой Всегда возвращает nil
передача управления Не передает управление на запросах выборки, если не происходит коммит транзакции в журнал упреждающей записи (WAL) Передает управление на запросах выборки или аналогичных: get() или pairs()

Configuration

Tarantool provides the ability to configure the full topology of a cluster and set parameters specific for concrete instances, such as connection settings, memory used to store data, logging, and snapshot settings. Each instance uses this configuration during startup to organize the cluster.

There are two approaches to configuring Tarantool:

Configuration overview

YAML configuration describes the full topology of a Tarantool cluster. A cluster’s topology includes the following elements, starting from the lower level:

groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            # ...
          instance002:
            # ...

You can flexibly configure a cluster’s settings on different levels: from global settings applied to all groups to parameters specific for concrete instances.

Примечание

All the available options are documented in the Configuration reference.

Configuration in a file

This section provides an overview on how to configure Tarantool in a YAML file.

Basic instance configuration

The example below shows a sample configuration of a single Tarantool instance:

groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
  • The instances section includes only one instance named instance001. The iproto.listen.uri option sets an address used to listen for incoming requests.
  • The replicasets section contains one replica set named replicaset001.
  • The groups section contains one group named group001.

Configuration scopes

This section shows how to control a scope the specified configuration option is applied to. Most of the configuration options can be applied to a specific instance, replica set, group, or to all instances globally.

  • Instance

    To apply certain configuration options to a specific instance, specify such options for this instance only. In the example below, iproto.listen is applied to instance001 only.

    groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'

  • Replica set

    In this example, iproto.listen is in effect for all instances in replicaset001.

    groups:
  group001:
    replicasets:
      replicaset001:
        iproto:
          listen:
          - uri: '127.0.0.1:3301'
        instances:
          instance001: { }

  • Group

    In this example, iproto.listen is in effect for all instances in group001.

    groups:
  group001:
    iproto:
      listen:
      - uri: '127.0.0.1:3301'
    replicasets:
      replicaset001:
        instances:
          instance001: { }

  • Global

    In this example, iproto.listen is applied to all instances of the cluster.

    iproto:
  listen:
  - uri: '127.0.0.1:3301'

groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001: { }

Configuration scopes above are listed in the order of their precedence – from highest to lowest. For example, if the same option is defined at the instance and global level, the instance’s value takes precedence over the global one.

Примечание

The Configuration reference contains information about scopes to which each configuration option can be applied.

Configuration scopes: Replica set example

The example below shows how specific configuration options work in different configuration scopes for a replica set with a manual failover. You can learn more about configuring replication from Replication tutorials.

credentials:
  users:
    replicator:
      password: 'topsecret'
      roles: [replication]

iproto:
  advertise:
    peer:
      login: replicator

replication:
  failover: manual

groups:
  group001:
    replicasets:
      replicaset001:
        leader: instance001
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
          instance002:
            iproto:
              listen:
              - uri: '127.0.0.1:3302'
          instance003:
            iproto:
              listen:
              - uri: '127.0.0.1:3303'

  • credentials (global)

    This section is used to create the replicator user and assign it the specified role. These options are applied globally to all instances.

  • iproto (global, instance)

    The iproto section is specified on both global and instance levels. The iproto.advertise.peer option specifies the parameters used by an instance to connect to another instance as a replica, for example, a URI, a login and password, or SSL parameters . In the example above, the option includes login only. An URI is taken from iproto.listen that is set on the instance level.

  • replication (global)

    The replication.failover global option sets a manual failover for all replica sets.

  • leader (replica set)

    The <replicaset-name>.leader option sets a master instance for replicaset001.

Enabling and configuring roles

An application role is a Lua module that implements specific functions or logic. You can turn on or off a particular role for certain instances in a configuration without restarting these instances.

There can be built-in Tarantool roles, roles provided by third-party Lua modules, or custom roles that are developed as a part of a cluster application. This section describes how to enable and configure roles. To learn how to develop custom roles, see Application roles.

Enabling a role

To turn on or off a role for a specific instance or a set of instances, use the roles configuration option. The example below shows how to enable the roles.crud-router role provided by the CRUD module using the roles option:

roles: [ roles.crud-router ]

Similarly, you can enable the roles.crud-storage role to make instances act as CRUD storages:

roles: [ roles.crud-storage ]

Example on GitHub: sharded_cluster_crud

Configuring a role

The roles_cfg option allows you to specify the configuration for each role. In this option, the role name is the key and the role configuration is the value.

The example below shows how to enable statistics on called operations by providing the roles.crud-router role’s configuration:

roles:
- roles.crud-router
- roles.metrics-export
roles_cfg:
  roles.crud-router:
    stats: true
    stats_driver: metrics
    stats_quantiles: true

Example on GitHub: sharded_cluster_crud_metrics

Roles and configuration scopes

As the most of configuration options, roles and their configurations can be defined at different levels. Given that the roles option has the array type and roles_cfg has the map type, there are some specifics of applying the configuration:

  • For roles, an instance’s role takes precedence over roles defined at another level. In the example below, instance001 has only role3:

    # ...
replicaset001:
  roles: [ role1, role2 ]
  instances:
    instance001:
      roles: [ role3 ]

    Learn more about the order of precedence for different configuration scopes in Configuration scopes.

  • For roles_cfg, the following rules are applied:

    • If a configuration for the same role is provided at different levels, an instance configuration takes precedence over the configuration defined at another level. In the example below, role1.greeting is 'Hi':

      # ...
replicaset001:
  roles_cfg:
    role1:
      greeting: 'Hello'
  instances:
    instance001:
      roles: [ role1 ]
      roles_cfg:
        role1:
          greeting: 'Hi'

    • If the configurations for different roles are provided at different levels, both configurations are applied at the instance level. In the example below, instance001 has role1.greeting set to 'Hi' and role2.farewell set to 'Bye':

      # ...
replicaset001:
  roles_cfg:
    role1:
      greeting: 'Hi'
  instances:
    instance001:
      roles: [ role1, role2 ]
      roles_cfg:
        role2:
          farewell: 'Bye'

Adding labels

Labels allow adding custom attributes to your cluster configuration. A label is an arbitrary key: value pair with a string key and value.

labels:
  dc: 'east'
  production: 'false'

Labels can be defined in any configuration scope. An instance receives labels from all scopes it belongs to. The labels section in a group or a replica set scope applies to all instances of the group or a replica set. To override these labels on the instance level or add instance-specific labels, define another labels section in the instance scope.

groups:
  group001:
    replicasets:
      replicaset001:
        labels:
          dc: 'east'
          production: 'false'
        instances:
          instance001:
            labels:
              rack: '10'
              production: 'true'

Example on GitHub: labels

To access instance labels from the application code, call the config:get() function:

myapp:instance001> require('config'):get('labels')
---
- production: 'true'
  rack: '10'
  dc: east
...

Labels can be used to direct function calls to instances that match certain criteria using the connpool module.

Predefined variables

In a configuration file, you can use the following predefined variables that are replaced with actual values at runtime:

  • instance_name
  • replicaset_name
  • group_name

To reference these variables in a configuration file, enclose them in double curly braces with whitespaces. In the example below, {{ instance_name }} is replaced with instance001.

groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            snapshot:
              dir: ./var/{{ instance_name }}/snapshots
            wal:
              dir: ./var/{{ instance_name }}/wals

As a result, the paths to snapshots and write-ahead logs differ for different instances.

Conditional configuration sections

A YAML configuration can include parts that apply only to instances that meet certain conditions. This is useful for cluster upgrade scenarios: during an upgrade, instances can be running different Tarantool versions and therefore require different configurations.

Conditional parts are defined in the conditional configuration section in the global scope. It includes one or more if subsections. Each if subsection defines conditions and configuration parts that apply to instances that meet these conditions.

The example below shows a conditional section for cluster upgrade from Tarantool 3.0.0 to Tarantool 3.1.0:

  • The user-defined label upgraded is true on instances that are running Tarantool 3.1.0 or later. On older versions, it is false.
  • Two compat options that were introduced in 3.1.0 are defined for Tarantool 3.1.0 instances. On older versions, they would cause an error.
conditional:
  - if: tarantool_version < 3.1.0
    labels:
      upgraded: 'false'
  - if: tarantool_version >= 3.1.0
    labels:
      upgraded: 'true'
    compat:
      box_error_serialize_verbose: 'new'
      box_error_unpack_type_and_code: 'new'

Example on GitHub: conditional

if sections can use one variable – tarantool_version. It contains a three-number Tarantool version and compares with values of the same format using the comparison operators >, <, >=, <=, ==, and !=. You can write complex conditions using the logical operators || (OR) and && (AND). Parentheses () can be used to define the operators precedence.

conditional:
  - if: (tarantool_version > 3.2.0 || tarantool_version == 3.1.3) && tarantool_version <= 3.99.0
    -- < ... >

If the same option is set in multiple if sections that are true for an instance, this option receives the value from the section declared last in the configuration.

Example:

conditional:
  - if: tarantool_version >= 3.0.0
    labels:
        version: '3.0' # applies to versions >= 3.0.0 and < 3.1.0
  - if: tarantool_version >= 3.1.0
    labels:
        version: '3.1+' # applies to versions >= 3.1.0

Environment variables

For each configuration parameter, Tarantool provides two sets of predefined environment variables:

For example, TT_IPROTO_LISTEN and TT_IPROTO_LISTEN_DEFAULT correspond to the iproto.listen option. TT_SNAPSHOT_DIR and TT_SNAPSHOT_DIR_DEFAULT correspond to the snapshot.dir option. To see all the supported environment variables, execute the tarantool command with the --help-env-list option.

$ tarantool --help-env-list

Примечание

There are also special TT_INSTANCE_NAME and TT_CONFIG environment variables that can be used to start the specified Tarantool instance with configuration from the given file.

Below are a few examples that show how to set environment variables of different types, like string, number, array, or map.

String

In this example, TT_LOG_LEVEL is used to set a logging level to CRITICAL:

$ export TT_LOG_LEVEL='crit'

Number

In this example, a logging level is set to CRITICAL using a corresponding numeric value:

$ export TT_LOG_LEVEL=3

Array

The examples below show how to set the TT_SHARDING_ROLES variable that accepts an array value. Arrays can be passed in two ways: using a simple …

$ export TT_SHARDING_ROLES=router,storage

… or JSON format:

$ export TT_SHARDING_ROLES='["router", "storage"]'

The simple format is applicable only to arrays containing scalar values.

Map

To assign map values to environment variables, you can also use simple or JSON formats. In the example below, TT_LOG_MODULES sets different logging levels for different modules using a simple format:

$ export TT_LOG_MODULES=module1=info,module2=error

In the next example, TT_ROLES_CFG is used to specify the value of a custom configuration for a role using a JSON format:

$ export TT_ROLES_CFG='{"greeter":{"greeting":"Hello"}}'

The simple format is applicable only to maps containing scalar values.

Array of maps

In the example below, TT_IPROTO_LISTEN is used to specify a listening host and port values:

$ export TT_IPROTO_LISTEN=['{"uri":"127.0.0.1:3311"}']

You can also pass several listening addresses:

$ export TT_IPROTO_LISTEN=['{"uri":"127.0.0.1:3311"}','{"uri":"127.0.0.1:3312"}']

Centralized configuration

Enterprise Edition

Centralized configuration storages are supported by the Enterprise Edition only.

Tarantool enables you to store configuration data in one place using a Tarantool or etcd-based storage. To achieve this, you need to:

  1. Set up a centralized configuration storage.

  2. Publish a cluster’s configuration to the storage.

  3. Configure a connection to the storage by providing a local YAML configuration with an endpoint address and key prefix in the config section:

    config:
  etcd:
    endpoints:
    - http://localhost:2379
    prefix: /myapp

Learn more from the following guide: Centralized configuration storages.

Configuration precedence

Tarantool configuration options are applied from multiple sources with the following precedence, from highest to lowest:

If the same option is defined in two or more locations, the option with the highest precedence is applied.

Centralized configuration storages

Enterprise Edition

Centralized configuration storages are supported by the Enterprise Edition only.

Examples on GitHub: centralized_config

Tarantool enables you to store a cluster’s configuration in one reliable place using a Tarantool or etcd-based storage:

With a local YAML configuration, you need to make sure that all cluster instances use identical configuration files:


Local configuration file

Using a centralized configuration storage, all instances get the actual configuration from one place:


Centralized configuration storage

This topic describes how to set up a configuration storage, publish a cluster configuration to this storage, and use this configuration for all cluster instances.

Setting up a configuration storage

Tarantool-based storage

To make a replica set act as a configuration storage, use the built-in config.storage role.

Configuring a storage

To configure a Tarantool-based storage, follow the steps below:

  1. Define a replica set topology and specify the following options at the replica set level:

    • Enable the config.storage role in roles.
    • Optionally, provide the role configuration in roles_cfg. In the example below, the status_check_interval option sets the interval (in seconds) of status checks.
    groups:
  group001:
    replicasets:
      replicaset001:
        roles: [ config.storage ]
        roles_cfg:
          config.storage:
            status_check_interval: 3
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:4401'
          instance002:
            iproto:
              listen:
              - uri: '127.0.0.1:4402'
          instance003:
            iproto:
              listen:
              - uri: '127.0.0.1:4403'

  2. Create a user and grant them the following privileges:

    • The read and write permissions to the config_storage and config_storage_meta spaces used to store configuration data.
    • The execute permission to universe to allow interacting with the storage using the tt utility.
    credentials:
  users:
    sampleuser:
      password: '123456'
      privileges:
      - permissions: [ read, write ]
        spaces: [ config_storage, config_storage_meta ]
      - permissions: [ execute ]
        universe: true

  3. Set the replication.failover option to election to enable automated failover:

    replication:
  failover: election

  4. Enable the MVCC transaction mode to provide linearizability of read operations:

    database:
  use_mvcc_engine: true

The resulting storage configuration might look as follows:

credentials:
  users:
    sampleuser:
      password: '123456'
      privileges:
      - permissions: [ read, write ]
        spaces: [ config_storage, config_storage_meta ]
      - permissions: [ execute ]
        universe: true
    replicator:
      password: 'topsecret'
      roles: [ replication ]

iproto:
  advertise:
    peer:
      login: replicator

replication:
  failover: election

database:
  use_mvcc_engine: true

groups:
  group001:
    replicasets:
      replicaset001:
        roles: [ config.storage ]
        roles_cfg:
          config.storage:
            status_check_interval: 3
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:4401'
          instance002:
            iproto:
              listen:
              - uri: '127.0.0.1:4402'
          instance003:
            iproto:
              listen:
              - uri: '127.0.0.1:4403'

You can find the full example here: tarantool_config_storage.

Starting a storage

To start instances of the configured storage, use the tt start command, for example:

$ tt start tarantool_config_storage

Learn more from the Starting and stopping instances section.

etcd-based storage

To learn how to set up an etcd-based configuration storage, consult the etcd documentation.

The example script below demonstrates how to use the etcdctl utility to create a user that has read and write access to configurations stored by the /myapp/ prefix:

etcdctl user add root:topsecret
etcdctl role add myapp_config_manager
etcdctl role grant-permission myapp_config_manager --prefix=true readwrite /myapp/
etcdctl user add sampleuser:123456
etcdctl user grant-role sampleuser myapp_config_manager
etcdctl auth enable

The credentials of this user should be specified when configuring a connection to the etcd cluster.

Publishing a cluster’s configuration

Publishing configuration using the tt utility

The tt utility provides the tt cluster command for managing centralized cluster configurations. The tt cluster publish command can be used to publish a cluster’s configuration to both Tarantool and etcd-based storages.

The example below shows how a tt environment and a layout of the application called myapp might look:

├── tt.yaml
├── source.yaml
└── instances.enabled
    └── myapp
        ├── config.yaml
        └── instances.yml
  • tt.yaml: a tt configuration file.
  • source.yaml contains a cluster’s configuration to be published.
  • config.yaml contains a local configuration used to connect to the centralized storage.
  • instances.yml specifies instances to run in the current environment. The configured instances are used by tt when starting a cluster. tt cluster publish ignores this configuration file.

To publish a cluster’s configuration (source.yaml) to a centralized storage, execute tt cluster publish as follows:

$ tt cluster publish "http://sampleuser:123456@localhost:2379/myapp" source.yaml

Executing this command publishes a cluster configuration by the /myapp/config/all path.

Примечание

You can see a cluster’s configuration using the tt cluster show command.

Publishing configuration using the „config“ module

The config module provides the API for interacting with a Tarantool-based configuration storage. The example below shows how to read a configuration stored in the source.yaml file using the fio module API and put this configuration by the /myapp/config/all path:

local fio = require('fio')
local cluster_config_handle = fio.open('../../source.yaml')
local cluster_config = cluster_config_handle:read()
local response = config.storage.put('/myapp/config/all', cluster_config)
cluster_config_handle:close()

Learn more from the config.storage API section.

Примечание

The net.box module provides the ability to monitor configuration updates by watching path or prefix changes. Learn more in conn:watch().

Publishing configuration using etcdctl

To publish a cluster’s configuration to etcd using the etcdctl utility, use the put command:

$ etcdctl put /myapp/config/all < source.yaml

Примечание

For etcd versions earlier than 3.4, you need to set the ETCDCTL_API environment variable to 3.

Configuring connection to a storage

To use a configuration from a centralized storage for your cluster, you need to provide connection settings in a local configuration file.

Configuring connection to a Tarantool storage

Connection options for a Tarantool-based storage should be specified in the config.storage section of the configuration file. In the example below, the following options are specified:

config:
  storage:
    endpoints:
      - uri: '127.0.0.1:4401'
        login: sampleuser
        password: '123456'
      - uri: '127.0.0.1:4402'
        login: sampleuser
        password: '123456'
      - uri: '127.0.0.1:4403'
        login: sampleuser
        password: '123456'
    prefix: /myapp
    timeout: 3
    reconnect_after: 5
  • endpoints specifies the list of configuration storage endpoints.
  • prefix sets a key prefix used to search a configuration. Tarantool searches keys by the following path: <prefix>/config/*. Note that <prefix> should start with a slash (/).
  • timeout specifies the interval (in seconds) to perform the status check of a configuration storage.
  • reconnect_after specifies how much time to wait (in seconds) before reconnecting to a configuration storage.

You can find the full example here: config_storage.

Configuring connection to an etcd storage

Connection options for etcd should be specified in the config.etcd section of the configuration file. In the example below, the following options are specified:

config:
  etcd:
    endpoints:
    - http://localhost:2379
    prefix: /myapp
    username: sampleuser
    password: '123456'
    http:
      request:
        timeout: 3
  • endpoints specifies the list of etcd endpoints.
  • prefix sets a key prefix used to search a configuration. Tarantool searches keys by the following path: <prefix>/config/*. Note that <prefix> should start with a slash (/).
  • username and password specify credentials used for authentication.
  • http.request.timeout configures a request timeout for an etcd server.

You can find the full example here: config_etcd.

Starting a cluster

The tt utility is the recommended way to start Tarantool instances. You can learn how to do this from the Starting and stopping instances section.

You can also use the tarantool command to start a Tarantool instance. In this case, you can eliminate creating a local configuration and provide connection settings using the following environment variables:

The example below shows how to provide etcd connection settings and start cluster instances using the tarantool command:

$ export TT_CONFIG_ETCD_ENDPOINTS=http://localhost:2379
$ export TT_CONFIG_ETCD_PREFIX=/myapp

$ tarantool --name instance001
$ tarantool --name instance002
$ tarantool --name instance003

Reloading configuration

By default, Tarantool watches keys with the specified prefix for changes in a cluster’s configuration and reloads a changed configuration automatically. If necessary, you can set the config.reload option to manual to turn off configuration reloading:

config:
  reload: 'manual'
  etcd:
    # ...

In this case, you can reload a configuration in an admin console or application code using the reload() function provided by the config module:

require('config'):reload()

Configuration in code

Примечание

Starting with the 3.0 version, the recommended way of configuring Tarantool is using a configuration file. Configuring Tarantool in code is considered a legacy approach.

This topic covers the specifics of configuring Tarantool in code using the box.cfg API. In this case, a configuration is stored in an initialization file - a Lua script with the specified configuration options. You can find all the available options in the Configuration reference.

Initialization file

If the command to start Tarantool includes an instance file, then Tarantool begins by invoking the Lua program in the file, which may have the name init.lua. The Lua program may get further arguments from the command line or may use operating-system functions, such as getenv(). The Lua program almost always begins by invoking box.cfg(), if the database server will be used or if ports need to be opened. For example, suppose init.lua contains the lines

#!/usr/bin/env tarantool
box.cfg{
    listen              = os.getenv("LISTEN_URI"),
    memtx_memory        = 33554432,
    pid_file            = "tarantool.pid",
    wal_max_size        = 2500
}
print('Starting ', arg[1])

and suppose the environment variable LISTEN_URI contains 3301, and suppose the command line is tarantool init.lua ARG. Then the screen might look like this:

$ export LISTEN_URI=3301
$ tarantool init.lua ARG
... main/101/init.lua C> Tarantool 2.8.3-0-g01023dbc2
... main/101/init.lua C> log level 5
... main/101/init.lua I> mapping 33554432 bytes for memtx tuple arena...
... main/101/init.lua I> recovery start
... main/101/init.lua I> recovering from './00000000000000000000.snap'
... main/101/init.lua I> set 'listen' configuration option to "3301"
... main/102/leave_local_hot_standby I> ready to accept requests
Starting  ARG
... main C> entering the event loop

If you wish to start an interactive session on the same terminal after initialization is complete, you can pass the -i command-line option.

Environment variables

Starting from version 2.8.1, you can specify configuration parameters via special environment variables. The name of a variable should have the following pattern: TT_<NAME>, where <NAME> is the uppercase name of the corresponding box.cfg parameter.

For example:

In case of an array value, separate the array elements by a comma without space:

export TT_REPLICATION="localhost:3301,localhost:3302"

If you need to pass additional parameters for URI, use the ? and & delimiters:

export TT_LISTEN="localhost:3301?param1=value1&param2=value2"

An empty variable (TT_LISTEN=) has the same effect as an unset one, meaning that the corresponding configuration parameter won’t be set when calling box.cfg{}.

Configuration parameters

Configuration parameters have the form:

box.cfg{[key = value [, key = value ...]]}

Configuration parameters can be set in a Lua initialization file, which is specified on the Tarantool command line.

Most configuration parameters are for allocating resources, opening ports, and specifying database behavior. All parameters are optional. Most of the parameters are dynamic, that is, they can be changed at runtime by calling box.cfg{} a second time. For example, the command below sets the listen port to 3301.

tarantool> box.cfg{ listen = 3301 }
2023-05-10 13:28:54.667 [31326] main/103/interactive I> tx_binary: stopped
2023-05-10 13:28:54.667 [31326] main/103/interactive I> tx_binary: bound to [::]:3301
2023-05-10 13:28:54.667 [31326] main/103/interactive/box.load_cfg I> set 'listen' configuration option to 3301
---
...

To see all the non-null parameters, execute box.cfg (no parentheses).

tarantool> box.cfg
---
- replication_skip_conflict: false
  wal_queue_max_size: 16777216
  feedback_host: https://feedback.tarantool.io
  memtx_dir: .
  memtx_min_tuple_size: 16
  -- other parameters --
...

To see a particular parameter value, call a corresponding box.cfg option. For example, box.cfg.listen shows the specified listen address.

tarantool> box.cfg.listen
---
- 3301
...

Listen URI

Some configuration parameters and some functions depend on a URI (Universal Resource Identifier). The URI string format is similar to the generic syntax for a URI schema. It may contain (in order):

Only a port number is always mandatory. A password is mandatory if a user name is specified unless the user name is „guest“.

Formally, the URI syntax is [host:]port or [username:password@]host:port. If a host is omitted, then «0.0.0.0» or «[::]» is assumed, meaning respectively any IPv4 address or any IPv6 address on the local machine. If username:password is omitted, then the «guest» user is assumed. Some examples:

URI fragment Example
port 3301
host:port 127.0.0.1:3301
username:password@host:port notguest:sesame@mail.ru:3301

In code, the URI value can be passed as a number (if only a port is specified) or a string:

box.cfg { listen = 3301 }

box.cfg { listen = "127.0.0.1:3301" }

In certain circumstances, a Unix domain socket may be used where a URI is expected, for example, unix/:/tmp/unix_domain_socket.sock or simply /tmp/unix_domain_socket.sock.

The uri module provides functions that convert URI strings into their components or turn components into URI strings.

Specifying several URIs

Starting from version 2.10.0, a user can open several listening iproto sockets on a Tarantool instance and, consequently, can specify several URIs in the configuration parameters such as box.cfg.listen and box.cfg.replication.

URI values can be set in a number of ways:

  • As a string with URI values separated by commas.

    box.cfg { listen = "127.0.0.1:3301, /unix.sock, 3302" }

  • As a table that contains URIs in the string format.

    box.cfg { listen = {"127.0.0.1:3301", "/unix.sock", "3302"} }

  • As an array of tables with the uri field.

    box.cfg { listen = {
        {uri = "127.0.0.1:3301"},
        {uri = "/unix.sock"},
        {uri = 3302}
    }
}

  • In a combined way – an array that contains URIs in both the string and the table formats.

    box.cfg { listen = {
        "127.0.0.1:3301",
        { uri = "/unix.sock" },
        { uri = 3302 }
    }
}

Also, starting from version 2.10.0, it is possible to specify additional parameters for URIs. You can do this in different ways:

  • Using the ? delimiter when URIs are specified in a string format.

    box.cfg { listen = "127.0.0.1:3301?p1=value1&p2=value2, /unix.sock?p3=value3" }

  • Using the params table: a URI is passed in a table with additional parameters in the «params» table. Parameters in the «params» table overwrite the ones from a URI string («value2» overwrites «value1» for p1 in the example below).

    box.cfg { listen = {
        "127.0.0.1:3301?p1=value1",
        params = {p1 = "value2", p2 = "value3"}
    }
}

  • Using the default_params table for specifying default parameter values.

    In the example below, two URIs are passed in a table. The default value for the p3 parameter is defined in the default_params table and used if this parameter is not specified in URIs. Parameters in the default_params table are applicable to all the URIs passed in a table.

    box.cfg { listen = {
        "127.0.0.1:3301?p1=value1",
        { uri = "/unix.sock", params = { p2 = "value2" } },
        default_params = { p3 = "value3" }
    }
}

The recommended way for specifying URI with additional parameters is the following:

box.cfg { listen = {
        {uri = "127.0.0.1:3301", params = {p1 = "value1"}},
        {uri = "/unix.sock", params = {p2 = "value2"}},
        {uri = 3302, params = {p3 = "value3"}}
    }
}

In case of a single URI, the following syntax also works:

box.cfg { listen = {
        uri = "127.0.0.1:3301",
        params = { p1 = "value1", p2 = "value2" }
    }
}

Traffic encryption

Enterprise Edition

Traffic encryption is supported by the Enterprise Edition only.

Since version 2.10.0, Tarantool Enterprise Edition has the built-in support for using SSL to encrypt the client-server communications over binary connections, that is, between Tarantool instances in a cluster or connecting to an instance via connectors using net.box.

Tarantool uses the OpenSSL library that is included in the delivery package. Note that SSL connections use only TLSv1.2.

Configuration

To configure traffic encryption, you need to set the special URI parameters for a particular connection. The parameters can be set for the following box.cfg options and net.box method:

Below is the list of the parameters. In the next section, you can find details and examples on what should be configured on both the server side and the client side.

  • transport – enables SSL encryption for a connection if set to ssl. The default value is plain, which means the encryption is off. If the parameter is not set, the encryption is off too. Other encryption-related parameters can be used only if the transport = 'ssl' is set.

    Example:

    local connection = require('net.box').connect({
    uri = 'admin:topsecret@127.0.0.1:3301',
    params = { transport = 'ssl',
               ssl_cert_file = 'certs/instance001/server001.crt',
               ssl_key_file = 'certs/instance001/server001.key',
               ssl_password = 'qwerty' }
})

  • ssl_key_file – a path to a private SSL key file. Mandatory for a server. For a client, it’s mandatory if the ssl_ca_file parameter is set for a server; otherwise, optional. If the private key is encrypted, provide a password for it in the ssl_password or ssl_password_file parameter.

  • ssl_cert_file – a path to an SSL certificate file. Mandatory for a server. For a client, it’s mandatory if the ssl_ca_file parameter is set for a server; otherwise, optional.

  • ssl_ca_file – a path to a trusted certificate authorities (CA) file. Optional. If not set, the peer won’t be checked for authenticity.

    Both a server and a client can use the ssl_ca_file parameter:

    • If it’s on the server side, the server verifies the client.
    • If it’s on the client side, the client verifies the server.
    • If both sides have the CA files, the server and the client verify each other.

  • ssl_ciphers – a colon-separated (:) list of SSL cipher suites the connection can use. See the Supported ciphers section for details. Optional. Note that the list is not validated: if a cipher suite is unknown, Tarantool just ignores it, doesn’t establish the connection and writes to the log that no shared cipher found.

  • ssl_password – a password for an encrypted private SSL key. Optional. Alternatively, the password can be provided in ssl_password_file.

  • ssl_password_file – a text file with one or more passwords for encrypted private SSL keys (each on a separate line). Optional. Alternatively, the password can be provided in ssl_password.

    Tarantool applies the ssl_password and ssl_password_file parameters in the following order:

    1. If ssl_password is provided, Tarantool tries to decrypt the private key with it.
    2. If ssl_password is incorrect or isn’t provided, Tarantool tries all passwords from ssl_password_file one by one in the order they are written.
    3. If ssl_password and all passwords from ssl_password_file are incorrect, or none of them is provided, Tarantool treats the private key as unencrypted.

Configuration example:

box.cfg{ listen = {
    uri = 'localhost:3301',
    params = {
        transport = 'ssl',
        ssl_key_file = '/path_to_key_file',
        ssl_cert_file = '/path_to_cert_file',
        ssl_ciphers = 'HIGH:!aNULL',
        ssl_password = 'topsecret'
    }
}}

Supported ciphers

Tarantool Enterprise supports the following cipher suites:

  • ECDHE-ECDSA-AES256-GCM-SHA384
  • ECDHE-RSA-AES256-GCM-SHA384
  • DHE-RSA-AES256-GCM-SHA384
  • ECDHE-ECDSA-CHACHA20-POLY1305
  • ECDHE-RSA-CHACHA20-POLY1305
  • DHE-RSA-CHACHA20-POLY1305
  • ECDHE-ECDSA-AES128-GCM-SHA256
  • ECDHE-RSA-AES128-GCM-SHA256
  • DHE-RSA-AES128-GCM-SHA256
  • ECDHE-ECDSA-AES256-SHA384
  • ECDHE-RSA-AES256-SHA384
  • DHE-RSA-AES256-SHA256
  • ECDHE-ECDSA-AES128-SHA256
  • ECDHE-RSA-AES128-SHA256
  • DHE-RSA-AES128-SHA256
  • ECDHE-ECDSA-AES256-SHA
  • ECDHE-RSA-AES256-SHA
  • DHE-RSA-AES256-SHA
  • ECDHE-ECDSA-AES128-SHA
  • ECDHE-RSA-AES128-SHA
  • DHE-RSA-AES128-SHA
  • AES256-GCM-SHA384
  • AES128-GCM-SHA256
  • AES256-SHA256
  • AES128-SHA256
  • AES256-SHA
  • AES128-SHA
  • GOST2012-GOST8912-GOST8912
  • GOST2001-GOST89-GOST89

Tarantool Enterprise static build has the embedded engine to support the GOST cryptographic algorithms. If you use these algorithms for traffic encryption, specify the corresponding cipher suite in the ssl_ciphers parameter, for example:

box.cfg{ listen = {
    uri = 'localhost:3301',
    params = {
        transport = 'ssl',
        ssl_key_file = '/path_to_key_file',
        ssl_cert_file = '/path_to_cert_file',
        ssl_ciphers = 'GOST2012-GOST8912-GOST8912'
    }
}}

For detailed information on SSL ciphers and their syntax, refer to OpenSSL documentation.

Using environment variables

The URI parameters for traffic encryption can also be set via environment variables, for example:

export TT_LISTEN="localhost:3301?transport=ssl&ssl_cert_file=/path_to_cert_file&ssl_key_file=/path_to_key_file"

Server-client configuration details

When configuring the traffic encryption, you need to specify the necessary parameters on both the server side and the client side. Below you can find the summary on the options and parameters to be used and examples of configuration.

Server side

  • Is configured via the box.cfg.listen option.
  • Mandatory URI parameters: transport, ssl_key_file and ssl_cert_file.
  • Optional URI parameters: ssl_ca_file, ssl_ciphers, ssl_password, and ssl_password_file.

Client side

  • Is configured via the box.cfg.replication option (see details) or net_box_object.connect().

Parameters:

  • If the server side has only the transport, ssl_key_file and ssl_cert_file parameters set, on the client side, you need to specify only transport = ssl as the mandatory parameter. All other URI parameters are optional.
  • If the server side also has the ssl_ca_file parameter set, on the client side, you need to specify transport, ssl_key_file and ssl_cert_file as the mandatory parameters. Other parameters – ssl_ca_file, ssl_ciphers, ssl_password, and ssl_password_file – are optional.

Configuration examples

Suppose, there is a master-replica set with two Tarantool instances:

  • 127.0.0.1:3301 – master (server)
  • 127.0.0.1:3302 – replica (client).

Examples below show the configuration related to connection encryption for two cases: when the trusted certificate authorities (CA) file is not set on the server side and when it does. Only mandatory URI parameters are mentioned in these examples.

  1. Without CA

  • 127.0.0.1:3301 – master (server)

    box.cfg{
    listen = {
        uri = '127.0.0.1:3301',
        params = {
            transport = 'ssl',
            ssl_key_file = '/path_to_key_file',
            ssl_cert_file = '/path_to_cert_file'
        }
    }
}

  • 127.0.0.1:3302 – replica (client)

    box.cfg{
    listen = {
        uri = '127.0.0.1:3302',
        params = {transport = 'ssl'}
    },
    replication = {
        uri = 'username:password@127.0.0.1:3301',
        params = {transport = 'ssl'}
    },
    read_only = true
}
  1. With CA

  • 127.0.0.1:3301 – master (server)

    box.cfg{
    listen = {
        uri = '127.0.0.1:3301',
        params = {
            transport = 'ssl',
            ssl_key_file = '/path_to_key_file',
            ssl_cert_file = '/path_to_cert_file',
            ssl_ca_file = '/path_to_ca_file'
        }
    }
}

  • 127.0.0.1:3302 – replica (client)

    box.cfg{
    listen = {
        uri = '127.0.0.1:3302',
        params = {
            transport = 'ssl',
            ssl_key_file = '/path_to_key_file',
            ssl_cert_file = '/path_to_cert_file'
        }
    },
    replication = {
        uri = 'username:password@127.0.0.1:3301',
        params = {
            transport = 'ssl',
            ssl_key_file = '/path_to_key_file',
            ssl_cert_file = '/path_to_cert_file'
        }
    },
    read_only = true
}

Starting a Tarantool instance

Below is the syntax for starting a Tarantool instance configured in a Lua initialization script:

$ tarantool LUA_INITIALIZATION_FILE [OPTION ...]

The tarantool command also provides a set of options that might be helpful for development purposes.

The command below starts a Tarantool instance configured in the init.lua file:

$ tarantool init.lua

Storage

This section contains guides on configuring a storage.

In-memory storage

Example on GitHub: memtx

In Tarantool, all data is stored in random-access memory (RAM) by default. For this purpose, the memtx storage engine is used.

This topic describes how to define basic settings related to in-memory storage in the memtx section of a YAML configuration – for example, memory size and maximum tuple size. For the specific settings related to allocator or sorting threads, check the corresponding memtx options in the Configuration reference.

Примечание

To estimate the required amount of memory, you can use the sizing calculator.

Memory size

In Tarantool, data is stored in spaces. Each space consists of tuples – the database records. To specify the amount of memory that Tarantool allocates to store tuples, use the memtx.memory configuration option.

In the example below, the memory size is set to 1 GB (1073741824 bytes):

memtx:
  memory: 1073741824

The server does not exceed this limit to allocate tuples. For indexes and connection information, additional memory is used.

When the memtx.memory limit is reached, INSERT or UPDATE requests fail with ER_MEMORY_ISSUE.

Tuple size

You can configure the minimum and the maximum tuple sizes in bytes.

To define the tuple size, use the memtx.min_tuple_size and memtx.max_tuple_size configuration options.

In the example, the minimum size is set to 8 bytes and the maximum size is set to 5 MB:

memtx:
  memory: 1073741824
  min_tuple_size: 8
  max_tuple_size: 5242880

Persistence

To ensure data persistence, Tarantool provides the abilities to:

This topic describes how to configure:

To learn more about the persistence mechanism in Tarantool, see the Persistence section. The formats of WAL and snapshot files are described in detail in the File formats section.

Configure the snapshots

Example on GitHub: snapshot

This section describes how to define snapshot settings in the snapshot section of a YAML configuration.

Примечание

To force immediate creation of a snapshot file, use the box.snapshot() function.

Set up automatic snapshot creation

In Tarantool, it is possible to automate the snapshot creation. Automatic creation is enabled by default and can be configured in two ways:

  • A new snapshot is taken once in a given period (see snapshot.by.interval).
  • A new snapshot is taken once the size of all WAL files created since the last snapshot exceeds a given limit (see snapshot.by.wal_size).

The snapshot.by.interval option sets up the checkpoint daemon that takes a new snapshot every snapshot.by.interval seconds. If the snapshot.by.interval option is set to zero, the checkpoint daemon is disabled.

The snapshot.by.wal_size option defines the maximum size in bytes for all WAL files created since the last snapshot taken. Once this size is exceeded, the checkpoint daemon takes a snapshot. Then, Tarantool garbage collector deletes the old WAL files.

The example shows how to specify the snapshot.by.interval and the snapshot.by.wal_size options:

by:
  interval: 7200
  wal_size: 1000000000000000000

In the example, a new snapshot is created in two cases:

  • every 2 hours (every 7200 seconds)
  • when the size for all WAL files created since the last snapshot reaches the size of 1e18 (1000000000000000000) bytes.

Specify a directory for snapshot files

To configure a directory where the snapshot files are stored, use the snapshot.dir configuration option. The example below shows how to specify a snapshot directory for instance001 explicitly:

instance001:
  snapshot:
    dir: 'var/lib/{{ instance_name }}/snapshots'

By default, WAL files and snapshot files are stored in the same directory var/lib/{{ instance_name }}. However, you can specify different directories for them. For example, you can place snapshots and write-ahead logs on different hard drives for better reliability:

instance001:
  snapshot:
    dir: '/media/drive1/snapshots'
  wal:
    dir: '/media/drive2/wals'

Configure a maximum number of stored snapshots

You can set a limit on the number of snapshots stored in the snapshot.dir directory using the snapshot.count option. Once the number of snapshots reaches the given limit, Tarantool garbage collector deletes the oldest snapshot file and any associated WAL files after the new snapshot is taken.

In the example below, the snapshot is created every two hours (every 7200 seconds) until there are three snapshots in the snapshot.dir directory. After creating a new snapshot (the fourth one), the oldest snapshot and the corresponding WALs are deleted.

count: 3
by:
  interval: 7200

Configure the write-ahead log

Example on GitHub: wal

This section describes how to define WAL settings in the wal section of a YAML configuration.

Set the WAL mode

The recording to the write-ahead log is enabled by default. It means that if an instance restart occurs, the data will be recovered. The recording to the WAL can be configured using the wal.mode configuration option.

There are two modes that enable writing to the WAL:

  • write (default) – enable WAL and write the data without waiting for the data to be flushed to the storage device.
  • fsync – enable WAL and ensure that the record is written to the storage device.

The example below shows how to specify the write WAL mode:

mode: 'write'

To turn the WAL writer off, set the wal.mode option to none.

Specify a directory for WAL files

To configure a directory where the WAL files are stored, use the wal.dir configuration option. The example below shows how to specify a directory for instance001 explicitly:

instance001:
  wal:
    dir: 'var/lib/{{ instance_name }}/wals'

Set an interval between scans

In case of replication or hot standby mode, Tarantool scans for changes in the WAL files every wal.dir_rescan_delay seconds. The example below shows how to specify the interval between scans:

dir_rescan_delay: 3

Set a maximum size for the WAL file

A new WAL file is created when the current one reaches the wal.max_size size. The configuration for this option might look as follows:

max_size: 268435456

Set a delay for the garbage collector

In Tarantool, the checkpoint daemon takes new snapshots at the given interval (see snapshot.by.interval). After an instance restart, the Tarantool garbage collector deletes the old WAL files.

To delay the immediate deletion of WAL files, use the wal.cleanup_delay configuration option. The delay eliminates possible erroneous situations when the master deletes WALs needed by replicas after restart. As a consequence, replicas sync with the master faster after its restart and don’t need to download all the data again.

In the example, the delay is set to 5 hours (18000 seconds):

cleanup_delay: 18000

Specify the WAL extensions

In Tarantool Enterprise, you can store an old and new tuple for each CRUD operation performed. A detailed description and examples of the WAL extensions are provided in the WAL extensions section.

See also: wal.ext.* configuration options.

Checkpoint daemon

The checkpoint daemon (snapshot daemon) is a constantly running fiber. The checkpoint daemon creates a schedule for the periodic snapshot creation based on the configuration options and the speed of file size growth. If enabled, the daemon makes new snapshot (.snap) files according to this schedule.

The work of the checkpoint daemon is based on the following configuration options:

If necessary, the checkpoint daemon also activates the Tarantool garbage collector that deletes old snapshots and WAL files.

Примечание

The memtx engine takes only regular snapshots with the interval set in the checkpoint daemon configuration.

The vinyl engine runs checkpointing in the background at all times.

Tarantool garbage collector

Tarantool garbage collector can be activated by the checkpoint daemon. The garbage collector tracks the snapshots that are to be relayed to a replica or needed by other consumers. When the files are no longer needed, Tarantool garbage collector deletes them.

Примечание

The garbage collector called by the checkpoint daemon is distinct from the Lua garbage collector which is for Lua objects, and distinct from the Tarantool garbage collector that specializes in handling shard buckets.

This garbage collector is called as follows:

If an old snapshot file is deleted, the Tarantool garbage collector also deletes any write-ahead log (.xlog) files that meet the following conditions:

Tarantool garbage collector also deletes obsolete vinyl .run files.

Tarantool garbage collector doesn’t delete a file in the following cases:

WAL extensions

Enterprise Edition

WAL extensions are available in the Enterprise Edition only.

WAL extensions allow you to add auxiliary information to each write-ahead log record. For example, you can enable storing an old and new tuple for each CRUD operation performed. This information might be helpful for implementing a CDC (Change Data Capture) utility that transforms a data replication stream.

See also: Configure the write-ahead log.

Configuration

WAL extensions are disabled by default. To configure them, use the wal.ext.* configuration options. Inside the wal.ext block, you can enable storing old and new tuples as follows:

Note that records with additional fields are replicated as follows:

Example

The table below demonstrates how write-ahead log records might look for the specific CRUD operations if storing old and new tuples is enabled for the bands space.

Operation Example WAL information
insert bands:insert{4, 'The Beatles', 1960}
new_tuple: [4, „The Beatles“, 1960]
tuple: [4, „The Beatles“, 1960]
delete bands:delete{4}
key: [4]
old_tuple: [4, „The Beatles“, 1960]
update bands:update({2}, {{'=', 2, 'Pink Floyd'}})
new_tuple: [2, „Pink Floyd“, 1965]
old_tuple: [2, „Scorpions“, 1965]
key: [2]
tuple: [[„=“, 2, „Pink Floyd“]]
upsert bands:upsert({2, 'Pink Floyd', 1965}, {{'=', 2, 'The Doors'}})
new_tuple: [2, „The Doors“, 1965]
old_tuple: [2, „Pink Floyd“, 1965]
operations: [[„=“, 2, „The Doors“]]
tuple: [2, „Pink Floyd“, 1965]
replace bands:replace{1, 'The Beatles', 1960}
old_tuple: [1, „Roxette“, 1986]
new_tuple: [1, „The Beatles“, 1960]
tuple: [1, „The Beatles“, 1960]

Storing both old and new tuples is especially useful for the update operation because a write-ahead log record contains only a key value.

Примечание

You can use the Printing the contents of .snap and .xlog files command to see the contents of a write-ahead log.

Defining and manipulating data

Tarantool stores data in spaces, which can be thought of as tables in a relational database. Every record or row in a space is called a tuple. A tuple may have any number of fields, and the fields may be of different types.

String data in fields are compared based on the specified collation rules. The user can provide hard limits for data values through constraints and link related spaces with foreign keys.

Tarantool supports highly customizable indexes of various types. In particular, indexes can be defined with generators like sequences.

There are six basic data operations in Tarantool: SELECT, INSERT, UPDATE, UPSERT, REPLACE, and DELETE. A number of complexity factors affects the resource usage of each function.

Tarantool allows describing the data schema but does not require it. The user can migrate a schema without migrating the data.

To ensure data persistence and recover quickly in case of failure, Tarantool uses mechanisms like the write-ahead log (WAL) and snapshots.

This section contains guides on performing data operations in Tarantool.

Data storage

Tuples

Tarantool operates data in the form of tuples.

tuple

A tuple is a group of data values in Tarantool’s memory. Think of it as a «database record» or a «row». The data values in the tuple are called fields.

When Tarantool returns a tuple value in the console, by default, it uses YAML format, for example: [3, 'Ace of Base', 1993].

Internally, Tarantool stores tuples as MsgPack arrays.

field

Fields are distinct data values, contained in a tuple. They play the same role as «row columns» or «record fields» in relational databases, with a few improvements:

  • fields can be composite structures, such as arrays or maps,
  • fields don’t need to have names.

A given tuple may have any number of fields, and the fields may be of different types.

The field’s number is the identifier of the field. Numbers are counted from base 1 in Lua and other 1-based languages, or from base 0 in languages like PHP or C/C++. So, 1 or 0 can be used in some contexts to refer to the first field of a tuple.

Spaces

Tarantool stores tuples in containers called spaces.

space

In Tarantool, a space is a primary container that stores data. It is analogous to tables in relational databases. Spaces contain tuples – the Tarantool name for database records. The number of tuples in a space is unlimited.

At least one space is required to store data with Tarantool. Each space has the following attributes:

  • a unique name specified by the user,
  • a unique numeric identifier which can be specified by the user, but usually is assigned automatically by Tarantool,
  • an engine: memtx (default) — in-memory engine, fast but limited in size, or vinyl — on-disk engine for huge data sets.

To be functional, a space also needs to have a primary index. It can also have secondary indexes.

Data types

Tarantool is both a database manager and an application server. Therefore a developer often deals with two type sets: the types of the programming language (such as Lua) and the types of the Tarantool storage format (MsgPack).

Lua versus MsgPack

Scalar / compound MsgPack type Lua type Example value
scalar nil cdata box.NULL
scalar boolean boolean true
scalar string string 'A B C'
scalar integer number 12345
scalar integer cdata 12345
scalar float64 (double) number 1.2345
scalar float64 (double) cdata 1.2345
scalar binary cdata [!!binary 3t7e]
scalar ext (for Tarantool decimal) cdata 1.2
scalar ext (for Tarantool datetime) cdata '2021-08-20T16:21:25.122999906 Europe/Berlin'
scalar ext (for Tarantool interval) cdata +1 months, 1 days
scalar ext (for Tarantool uuid) cdata 12a34b5c-de67-8f90-123g-h4567ab8901
compound map table (with string keys) {'a': 5, 'b': 6}
compound array table (with integer keys) [1, 2, 3, 4, 5]
compound array tuple (cdata) [12345, 'A B C']

Примечание

MsgPack values have variable lengths. So, for example, the smallest number requires only one byte, but the largest number requires nine bytes.

Примечание

The Lua nil type is encoded as MsgPack nil but decoded as msgpack.NULL.

Field type details

nil

In Lua, the nil type has only one possible value, also called nil. Tarantool displays it as null when using the default YAML format. Nil may be compared to values of any types with == (is-equal) or ~= (is-not-equal), but other comparison operations will not work. Nil may not be used in Lua tables; the workaround is to use box.NULL because nil == box.NULL is true. Example: nil.

boolean

A boolean is either true or false.

Example: true.

integer

The Tarantool integer type is for integers between -9223372036854775808 and 18446744073709551615, which is about 18 quintillion. This type corresponds to the number type in Lua and to the integer type in MsgPack.

Example: -2^63.

unsigned

The Tarantool unsigned type is for integers between 0 and 18446744073709551615. So it is a subset of integer.

Example: 123456.

double

The double field type exists mainly to be equivalent to Tarantool/SQL’s DOUBLE data type. In msgpuck.h (Tarantool’s interface to MsgPack), the storage type is MP_DOUBLE and the size of the encoded value is always 9 bytes. In Lua, fields of the double type can only contain non-integer numeric values and cdata values with double floating-point numbers.

Examples: 1.234, -44, 1.447e+44.

To avoid using the wrong kind of values inadvertently, use ffi.cast() when searching or changing double fields. For example, instead of space_object:insert{value} use ffi = require('ffi') ... space_object:insert({ffi.cast('double',value)}).

Example:

s = box.schema.space.create('s', {format = {{'d', 'double'}}})
s:create_index('ii')
s:insert({1.1})
ffi = require('ffi')
s:insert({ffi.cast('double', 1)})
s:insert({ffi.cast('double', tonumber('123'))})
s:select(1.1)
s:select({ffi.cast('double', 1)})

Arithmetic with cdata double will not work reliably, so for Lua, it is better to use the number type. This warning does not apply for Tarantool/SQL because Tarantool/SQL does implicit casting.

number

The Tarantool number field may have both integer and floating-point values, although in Lua a number is a double-precision floating-point.

Tarantool will try to store a Lua number as floating-point if the value contains a decimal point or is very large (greater than 100 trillion = 1e14), otherwise Tarantool will store it as an integer. To ensure that even very large numbers are stored as integers, use the tonumber64 function, or the LL (Long Long) suffix, or the ULL (Unsigned Long Long) suffix. Here are examples of numbers using regular notation, exponential notation, the ULL suffix and the tonumber64 function: -55, -2.7e+20, 100000000000000ULL, tonumber64('18446744073709551615').

You can also use the ffi module to specify a C type to cast the number to. In this case, the number will be stored as cdata.

decimal

The Tarantool decimal type is stored as a MsgPack ext (Extension). Values with the decimal type are not floating-point values although they may contain decimal points. They are exact with up to 38 digits of precision.

Example: a value returned by a function in the decimal module.

datetime

Introduced in v. 2.10.0. The Tarantool datetime type facilitates operations with date and time, accounting for leap years or the varying number of days in a month. It is stored as a MsgPack ext (Extension). Operations with this data type use code from c-dt, a third-party library.

For more information, see Module datetime.

interval

Since: v. 2.10.0

The Tarantool interval type represents periods of time. They can be added to or subtracted from datetime values or each other. Operations with this data type use code from c-dt, a third-party library. The type is stored as a MsgPack ext (Extension). For more information, see Module datetime.

string

A string is a variable-length sequence of bytes, usually represented with alphanumeric characters inside single quotes. In both Lua and MsgPack, strings are treated as binary data, with no attempts to determine a string’s character set or to perform any string conversion – unless there is an optional collation. So, usually, string sorting and comparison are done byte-by-byte, without any special collation rules applied. For example, numbers are ordered by their point on the number line, so 2345 is greater than 500; meanwhile, strings are ordered by the encoding of the first byte, then the encoding of the second byte, and so on, so '2345' is less than '500'.

Example: 'A, B, C'.

bin

A bin (binary) value is not directly supported by Lua but there is a Tarantool type varbinary. See the varbinary module reference for details.

Example: "\65 \66 \67".

uuid

The Tarantool uuid type is used for Universally Unique Identifiers. Since version 2.4.1 Tarantool stores uuid values as a MsgPack ext (Extension).

Example: 64d22e4d-ac92-4a23-899a-e5934af5479.

array

An array is represented in Lua with {...} (braces).

Examples: lists of numbers representing points in geometric figures: {10, 11}, {3, 5, 9, 10}.

table

Lua tables with string keys are stored as MsgPack maps; Lua tables with integer keys starting with 1 are stored as MsgPack arrays. Nils may not be used in Lua tables; the workaround is to use box.NULL.

Example: a box.space.tester:select() request will return a Lua table.

tuple

A tuple is a light reference to a MsgPack array stored in the database. It is a special type (cdata) to avoid conversion to a Lua table on retrieval. A few functions may return tables with multiple tuples. For tuple examples, see box.tuple.

scalar

Values in a scalar field can be boolean, integer, unsigned, double, number, decimal, string, uuid, or varbinary; but not array, map, or tuple.

Examples: true, 1, 'xxx'.

any

Values in a field of this type can be boolean, integer, unsigned, double, number, decimal, string, uuid, varbinary, array, map, or tuple.

Examples: true, 1, 'xxx', {box.NULL, 0}.

Examples

Examples of insert requests with different field types:

tarantool> box.space.K:insert{1,nil,true,'A B C',12345,1.2345}
---
- [1, null, true, 'A B C', 12345, 1.2345]
...
tarantool> box.space.K:insert{2,{['a']=5,['b']=6}}
---
- [2, {'a': 5, 'b': 6}]
...
tarantool> box.space.K:insert{3,{1,2,3,4,5}}
---
- [3, [1, 2, 3, 4, 5]]
...

Indexed field types

To learn more about what values can be stored in indexed fields, read the Indexes section.

Collations

By default, when Tarantool compares strings, it uses the so-called binary collation. It only considers the numeric value of each byte in a string. For example, the encoding of 'A' (what used to be called the «ASCII value») is 65, the encoding of 'B' is 66, and the encoding of 'a' is 98. Therefore, if the string is encoded with ASCII or UTF-8, then 'A' < 'B' < 'a'.

Binary collation is the best choice for fast deterministic simple maintenance and searching with Tarantool indexes.

But if you want the ordering that you see in phone books and dictionaries, then you need Tarantool’s optional collations, such as unicode and unicode_ci, which allow for 'a' < 'A' < 'B' and 'a' == 'A' < 'B' respectively.

The unicode and unicode_ci optional collations use the ordering according to the Default Unicode Collation Element Table (DUCET) and the rules described in Unicode® Technical Standard #10 Unicode Collation Algorithm (UTS #10 UCA). The only difference between the two collations is about weights:

As an example, take some Russian words:

'ЕЛЕ'
'елейный'
'ёлка'
'еловый'
'елозить'
'Ёлочка'
'ёлочный'
'ЕЛь'
'ель'

…and show the difference in ordering and selecting by index:

In all, collation involves much more than these simple examples of upper case / lower case and accented / unaccented equivalence in alphabets. We also consider variations of the same character, non-alphabetic writing systems, and special rules that apply for combinations of characters.

For English, Russian, and most other languages and use cases, use the «unicode» and «unicode_ci» collations. If you need Cyrillic letters „Е“ and „Ё“ to have the same level-1 weights, try the Kyrgyz collation.

The tailored optional collations: for other languages, Tarantool supplies tailored collations for every modern language that has more than a million native speakers, and for specialized situations such as the difference between dictionary order and telephone book order. Run box.space._collation:select() to see the complete list.

The tailored collation names have the form unicode_[language code]_[strength], where language code is a standard 2-character or 3-character language abbreviation, and strength is s1 for «primary strength» (level-1 weights), s2 for «secondary», s3 for «tertiary». Tarantool uses the same language codes as the ones in the «list of tailorable locales» on man pages of Ubuntu and Fedora. Charts explaining the precise differences from DUCET order are in the Common Language Data Repository.

Default values

Default values are assigned to tuple fields automatically if these fields are skipped during the tuple insert or update.

You can specify a default value for a field in the space_object:format() call that defines the space format. Default values apply regardless of the field nullability: any tuple in which the field is skipped or set to nil receives the default value.

Default values can be set in two ways: explicitly or using a function.

Explicit default values

Explicit default values are defined in the default parameter of the field declaration in a space_object:format() call.

local books = box.schema.space.create('books')
books:format({
    { name = 'id', type = 'number' },
    { name = 'name', type = 'string' },
    { name = 'year', type = 'number', default = 2024 },
})
books:create_index('primary', { parts = { 1 } })

To use a default value for a field, skip it or assign nil:

books:insert { 1, 'Thinking in Java' }
books:insert { 2, 'How to code in Go', nil }

Any Lua object that can be evaluated during the space_object.format() call may be used as a default value, for example:

  • a constant: default = 100
  • an initialized variable: default = default_size
  • an expression: default = 10 + default_size
  • a function return value: default = count_default()

Важно

Explicit default values are evaluated only when setting the space format. If you use a variable as a default value, its further assignments do not affect the default value.

To change the default values, call space_object:format() again.

See also the space_object:format() reference.

Default functions

A default value can be defined as a return value of a stored Lua function. To be the default, a function must be created with box.schema.func.create() with the function body and return one value of the field’s type. It also must not yield.

box.schema.func.create('current_year', {
    language = 'Lua',
    body = "function() return require('datetime').now().year end"
})

Default functions are set in the default_func parameter of the field declaration in a space_object:format() call. To make a function with no arguments the default for a field, specify its name:

local books = box.schema.space.create('books')
books:format({
    { name = 'id', type = 'unsigned' },
    { name = 'isbn', type = 'string' },
    { name = 'title', type = 'string' },
    { name = 'year', type = 'unsigned', default_func = 'current_year' }
})
books:create_index('primary', { parts = { 1 } })

A default function can also have one argument.

box.schema.func.create('randomize', {
    language = 'Lua',
    body = "function(limit) return math.random(limit.min, limit.max) end"
})

To pass the function argument when setting the default, specify it in the default parameter of the space_object:format() call:

books:format({
    { name = 'id', type = 'unsigned', default_func= 'randomize', default = {min = 0, max = 1000} },
    { name = 'isbn', type = 'string' },
    { name = 'title', type = 'string' },
    { name = 'year', type = 'unsigned', default_func = 'current_year' }
})

Примечание

A key difference between a default function (default_func = 'count_default') and a function return value used as a field default value (default = count_default()) is the following:

  • A default function is called every time a default value must be produced, that is, a tuple is inserted or updated without specifying the field.
  • A return value used a field default value: the function is called once when setting the space format. Then, all tuples receive the result of this exact call if the field is not specified.

See also the space_object.format() reference.

Constraints

For better control over stored data, Tarantool supports constraints – user-defined limitations on the values of certain fields or entire tuples. Together with data types, constraints allow limiting the ranges of available field values both syntactically and semantically.

For example, the field age typically has the number type, so it cannot store strings or boolean values. However, it can still have values that don’t make sense, such as negative numbers. This is where constraints come to help.

Constraint types

There are two types of constraints in Tarantool:

  • Field constraints check that the value being assigned to a field satisfies a given condition. For example, age must be non-negative.
  • Tuple constraints check complex conditions that can involve all fields of a tuple. For example, a tuple contains a date in three fields: year, month, and day. You can validate day values based on the month value (and even year if you consider leap years).

Field constraints work faster, while tuple constraints allow implementing a wider range of limitations.

Constraint functions

Constraints use stored Lua functions or SQL expressions, which must return true when the constraint is satisfied. Other return values (including nil) and exceptions make the check fail and prevent tuple insertion or modification.

To create a constraint function, call box.schema.func.create() with the function definition specified in the body attribute.

Constraint functions take two parameters:

  • The tuple and the constraint name for tuple constraints.

    -- Define a tuple constraint function --
box.schema.func.create('check_person', {
    language = 'LUA',
    is_deterministic = true,
    body = 'function(t, c) return (t.age >= 0 and #(t.name) > 3) end'
})

    Предупреждение

    Tarantool doesn’t check field names used in tuple constraint functions. If a field referenced in a tuple constraint gets renamed, this constraint will break and prevent further insertions and modifications in the space.

  • The field value and the constraint name for field constraints.

    -- Define a field constraint function --
box.schema.func.create('check_age', {
    language = 'LUA',
    is_deterministic = true,
    body = 'function(f, c) return (f >= 0 and f < 150) end'
})

Creating constraints

To create a constraint in a space, specify the corresponding function’s name in the constraint parameter:

  • Tuple constraints: when creating or altering a space.

    -- Create a space with a tuple constraint --
customers = box.schema.space.create('customers', {constraint = 'check_person'})

  • Field constraints: when setting up the space format.

    -- Specify format with a field constraint --
box.space.customers:format({
    {name = 'id', type = 'number'},
    {name = 'name', type = 'string'},
    {name = 'age',  type = 'number', constraint = 'check_age'},
})

In both cases, constraint can contain multiple function names passed as a tuple. Each constraint can have an optional name:

-- Create one more tuple constraint --
box.schema.func.create('another_constraint',
    {language = 'LUA', is_deterministic = true, body = 'function(t, c) return true end'})

-- Set two constraints with optional names --
box.space.customers:alter{
    constraint = { check1 = 'check_person', check2 = 'another_constraint'}
}

Примечание

When adding a constraint to an existing space with data, Tarantool checks it against the stored data. If there are fields or tuples that don’t satisfy the constraint, it won’t be applied to the space.

Foreign keys

Foreign keys provide links between related fields, therefore maintaining the referential integrity of the database.

Fields can contain values that exist only in other fields. For example, a shop order always belongs to a customer. Hence, all values of the customer field of the orders space must also exist in the id field of the customers space. In this case, customers is a parent space for orders (its child space). When two spaces are linked with a foreign key, each time a tuple is inserted or modified in the child space, Tarantool checks that a corresponding value is present in the parent space.

../../../_images/foreign_key.svg

Примечание

A foreign key can link a field to another field in the same space. In this case, the child field must be nullable. Otherwise, it is impossible to insert the first tuple in such a space because there is no parent tuple to which it can link.

Foreign key types

There are two types of foreign keys in Tarantool:

  • Field foreign keys check that the value being assigned to a field is present in a particular field of another space. For example, the customer value in a tuple from the orders space must match an id stored in the customers space.
  • Tuple foreign keys check that multiple fields of a tuple have a match in another space. For example, if the orders space has fields customer_id and customer_name, a tuple foreign key can check that the customers space contains a tuple with both these values in the corresponding fields.

Field foreign keys work faster while tuple foreign keys allow implementing more strict references.

Creating foreign keys

Важно

For each foreign key, there must exist a parent space index that includes all its fields.

To create a foreign key in a space, specify the parent space and linked fields in the foreign_key parameter. Parent spaces can be referenced by name or by id. When linking to the same space, the space can be omitted. Fields can be referenced by name or by number:

  • Field foreign keys: when setting up the space format.

    -- Create a space with a field foreign key --
box.schema.space.create('orders')

box.space.orders:format({
    {name = 'id',   type = 'number'},
    {name = 'customer_id', foreign_key = {space = 'customers', field = 'id'}},
    {name = 'price_total', type = 'number'},
})

  • Tuple foreign keys: when creating or altering a space. Note that for foreign keys with multiple fields there must exist an index that includes all these fields.

    -- Create a space with a tuple foreign key --
box.schema.space.create("orders", {
    foreign_key = {
        space = 'customers',
        field = {customer_id = 'id', customer_name = 'name'}
    }
})

box.space.orders:format({
    {name = "id", type = "number"},
    {name = "customer_id" },
    {name = "customer_name"},
    {name = "price_total", type = "number"},
})

Примечание

Type can be omitted for foreign key fields because it’s defined in the parent space.

Foreign keys can have an optional name.

-- Set a foreign key with an optional name --
box.space.orders:alter{
    foreign_key = {
        customer = {
            space = 'customers',
            field = { customer_id = 'id', customer_name = 'name'}
        }
    }
}

A space can have multiple tuple foreign keys. In this case, they all must have names.

-- Set two foreign keys: names are mandatory --
box.space.orders:alter{
    foreign_key = {
        customer = {
            space = 'customers',
            field = {customer_id = 'id', customer_name = 'name'}
        },
        item = {
            space = 'items',
            field = {item_id = 'id'}
        }
    }
}

Tarantool performs integrity checks upon data modifications in parent spaces. If you try to remove a tuple referenced by a foreign key or an entire parent space, you will get an error.

Важно

Renaming parent spaces or referenced fields may break the corresponding foreign keys and prevent further insertions or modifications in the child spaces.

Индексы

Basics

Индекс — это специальная структура данных, которая хранит группу ключевых значений и указателей. Индекс используется для эффективного управления данными.

As with spaces, you should specify the index name and let Tarantool come up with a unique numeric identifier («index id»).

An index always has a type. The default index type is TREE. TREE indexes are provided by all Tarantool engines, can index unique and non-unique values, support partial key searches, comparisons, and ordered results. Additionally, the memtx engine supports HASH, RTREE and BITSET indexes.

Индекс может быть составным (multi-part), то есть можно объявить, что ключ индекса состоит из двух или более полей в кортеже в любом порядке. Например, для обычного TREE-индекса максимальное количество частей равно 255.

Индекс может быть уникальным, то есть можно объявить, что недопустимо дважды задавать одно значение ключа.

Первый индекс, определенный для спейса, называется первичный индекс (primary key). Он должен быть уникальным. Все остальные индексы называются вторичными индексами (secondary), они могут строиться по неуникальным значениям.

Indexes have certain limitations. See details on page Limitations.

To create a generator for indexes, you can use a sequence object. Learn how to do it in the tutorial.

Indexed field types

Not to be confused with index types – the types of the data structure that is an index. See more about index types below.

Indexes restrict values that Tarantool can store with MsgPack. This is why, for example, 'unsigned' and 'integer' are different field types, although in MsgPack they are both stored as integer values. An 'unsigned' index contains only non-negative integer values, while an ‘integer’ index contains any integer values.

The default field type is 'unsigned' and the default index type is TREE. Although 'nil' is not a legal indexed field type, indexes may contain nil as a non-default option.

To learn more about field types, check the Field type details section.

Field type name string Field type Index type
'boolean' boolean TREE or HASH
'integer' (may also be called 'int') integer, which may include unsigned values TREE or HASH
'unsigned' (may also be called 'uint' or 'num', but 'num' is deprecated) unsigned TREE, BITSET, or HASH
'double' double TREE or HASH
'number' number, which may include integer, double, or decimal values TREE or HASH
'decimal' decimal TREE or HASH
'string' (may also be called 'str') string TREE, BITSET, or HASH
'varbinary' varbinary TREE, HASH, or BITSET (since version 2.7.1)
'uuid' uuid TREE or HASH
'datetime' datetime TREE
'array' array RTREE
'map' table Cannot be indexed
'scalar' may include nil, boolean, integer, unsigned, number, decimal, string, varbinary, or uuid values |
When a scalar field contains values of different underlying types, the key order is: nils, then booleans, then numbers, then strings, then varbinaries, then uuids.		 TREE or HASH

Index types

An index always has a type. Different types are intended for different usage scenarios.

We give an overview of index features in the following table:

Feature TREE HASH RTREE BITSET
unique + + - -
non-unique + - + +
is_nullable + - - -
can be multi-part + + - -
multikey + - - -
partial-key search + - - -
can be primary key + + - -
exclude_null (version 2.8+) + - - -
Pagination (the after option) + - - -
iterator types ALL, EQ, REQ, GT, GE, LT, LE ALL, EQ ALL, EQ, GT, GE, LT, LE, OVERLAPS, NEIGHBOR ALL, EQ, BITS_ALL_SET, BITS_ANY_SET, BITS_ALL_NOT_SET

Примечание

In 2.11.0, the GT index type is deprecated for HASH indexes.

TREE indexes

The default index type is „TREE“. TREE indexes are provided by memtx and vinyl engines, can index unique and non-unique values, support partial key searches, comparisons and ordered results.

This is a universal type of indexes, for most cases it will be the best choice.

Additionally, memtx engine supports HASH, RTREE and BITSET indexes.

HASH indexes

HASH indexes require unique fields and loses to TREE in almost all respects. So we do not recommend to use it in the applications. HASH is now present in Tarantool mainly because of backward compatibility.

Here are some tips. Do not use HASH index:

  • just if you want to
  • if you think that HASH is faster with no performance metering
  • if you want to iterate over the data
  • for primary key
  • as an only index

Use HASH index:

  • if it is a secondary key
  • if you 100% won’t need to make it non-unique
  • if you have taken measurements on your data and you see an accountable increase in performance
  • if you save every byte on tuples (HASH is a little more compact)

RTREE indexes

RTREE is a multidimensional index supporting up to 20 dimensions. It is used especially for indexing spatial information, such as geographical objects. In this example we demonstrate spatial searches via RTREE index.

RTREE index could not be primary, and could not be unique. The option list of this type of index may contain dimension and distance options. The parts definition must contain the one and only part with type array. RTREE index can accept two types of distance functions: euclid and manhattan.

Предупреждение

Currently, the isolation level of RTREE indexes in MVCC transaction mode is read-committed (not serializable, as stated). If a transaction uses these indexes, it can read committed or confirmed data (depending on the isolation level). However, the indexes are subject to different anomalies that can make them unserializable.

Example 1:

my_space = box.schema.create_space("tester")
my_space:format({ { type = 'number', name = 'id' }, { type = 'array', name = 'content' } })
hash_index = my_space:create_index('primary', { type = 'tree', parts = {'id'} })
rtree_index = my_space:create_index('spatial', { type = 'RTREE', unique = false, parts = {'content'} })

Corresponding tuple field thus must be an array of 2 or 4 numbers. 2 numbers mean a point {x, y}; 4 numbers mean a rectangle {x1, y1, x2, y2}, where (x1, y1) and (x2, y2) - diagonal point of the rectangle.

my_space:insert{1, {1, 1}}
my_space:insert{2, {2, 2, 3, 3}}

Selection results depend on a chosen iterator. The default EQ iterator searches for an exact rectangle, a point is treated as zero width and height rectangle:

tarantool> rtree_index:select{1, 1}
---
- - [1, [1, 1]]
...

tarantool> rtree_index:select{1, 1, 1, 1}
---
- - [1, [1, 1]]
...

tarantool> rtree_index:select{2, 2}
---
- []
...

tarantool> rtree_index:select{2, 2, 3, 3}
---
- - [2, [2, 2, 3, 3]]
...

Iterator ALL, which is the default when no key is specified, selects all tuples in arbitrary order:

tarantool> rtree_index:select{}
---
- - [1, [1, 1]]
  - [2, [2, 2, 3, 3]]
...

Iterator LE (less or equal) searches for tuples with their rectangles within a specified rectangle:

tarantool> rtree_index:select({1, 1, 2, 2}, {iterator='le'})
---
- - [1, [1, 1]]
...

Iterator LT (less than, or strictly less) searches for tuples with their rectangles strictly within a specified rectangle:

tarantool> rtree_index:select({0, 0, 3, 3}, {iterator = 'lt'})
---
- - [1, [1, 1]]
...

Iterator GE searches for tuples with a specified rectangle within their rectangles:

tarantool> rtree_index:select({1, 1}, {iterator = 'ge'})
---
- - [1, [1, 1]]
...

Iterator GT searches for tuples with a specified rectangle strictly within their rectangles:

tarantool> rtree_index:select({2.1, 2.1, 2.9, 2.9}, {iterator = 'gt'})
---
- []
...

Iterator OVERLAPS searches for tuples with their rectangles overlapping specified rectangle:

tarantool> rtree_index:select({0, 0, 10, 2}, {iterator='overlaps'})
---
- - [1, [1, 1]]
  - [2, [2, 2, 3, 3]]
...

Iterator NEIGHBOR searches for all tuples and orders them by distance to the specified point:

tarantool> for i=1,10 do
         >    for j=1,10 do
         >        my_space:insert{i*10+j, {i, j, i+1, j+1}}
         >    end
         > end
---
...

tarantool> rtree_index:select({1, 1}, {iterator = 'neighbor', limit = 5})
---
- - [11, [1, 1, 2, 2]]
  - [12, [1, 2, 2, 3]]
  - [21, [2, 1, 3, 2]]
  - [22, [2, 2, 3, 3]]
  - [31, [3, 1, 4, 2]]
...

Example 2:

3D, 4D and more dimensional RTREE indexes work in the same way as 2D except that user must specify more coordinates in requests. Here’s short example of using 4D tree:

tarantool> my_space = box.schema.create_space("tester")
tarantool> my_space:format{ { type = 'number', name = 'id' }, { type = 'array', name = 'content' } }
tarantool> primary_index = my_space:create_index('primary', { type = 'TREE', parts = {'id'} })
tarantool> rtree_index = my_space:create_index('spatial', { type = 'RTREE', unique = false, dimension = 4, parts = {'content'} })
tarantool> my_space:insert{1, {1, 2, 3, 4}} -- insert 4D point
tarantool> my_space:insert{2, {1, 1, 1, 1, 2, 2, 2, 2}} -- insert 4D box

tarantool> rtree_index:select{1, 2, 3, 4} -- find exact point
---
- - [1, [1, 2, 3, 4]]
...

tarantool> rtree_index:select({0, 0, 0, 0, 3, 3, 3, 3}, {iterator = 'LE'}) -- select from 4D box
---
- - [2, [1, 1, 1, 1, 2, 2, 2, 2]]
...

tarantool> rtree_index:select({0, 0, 0, 0}, {iterator = 'neighbor'}) -- select neighbours
---
- - [2, [1, 1, 1, 1, 2, 2, 2, 2]]
  - [1, [1, 2, 3, 4]]
...

Примечание

Keep in mind that select NEIGHBOR iterator with unset limits extracts the entire space in order of increasing distance. And there can be tons of data, and this can affect the performance.

And another frequent mistake is to specify iterator type without quotes, in such way: rtree_index:select(rect, {iterator = LE}). This leads to silent EQ select, because LE is undefined variable and treated as nil, so iterator is unset and default used.

BITSET indexes

Bitset is a bit mask. You should use it when you need to search by bit masks. This can be, for example, storing a vector of attributes and searching by these attributes.

Предупреждение

Currently, the isolation level of BITSET indexes in MVCC transaction mode is read-committed (not serializable, as stated). If a transaction uses these indexes, it can read committed or confirmed data (depending on the isolation level). However, the indexes are subject to different anomalies that can make them unserializable.

Example 1:

The following script shows creating and searching with a BITSET index. Notice that BITSET cannot be unique, so first a primary-key index is created, and bit values are entered as hexadecimal literals for easier reading.

tarantool> my_space = box.schema.space.create('space_with_bitset')
tarantool> my_space:create_index('primary_index', {
         >   parts = {1, 'string'},
         >   unique = true,
         >   type = 'TREE'
         > })
tarantool> my_space:create_index('bitset_index', {
         >   parts = {2, 'unsigned'},
         >   unique = false,
         >   type = 'BITSET'
         > })
tarantool> my_space:insert{'Tuple with bit value = 01', 0x01}
tarantool> my_space:insert{'Tuple with bit value = 10', 0x02}
tarantool> my_space:insert{'Tuple with bit value = 11', 0x03}
tarantool> my_space.index.bitset_index:select(0x02, {
         >   iterator = box.index.EQ
         > })
---
- - ['Tuple with bit value = 10', 2]
...
tarantool> my_space.index.bitset_index:select(0x02, {
         >   iterator = box.index.BITS_ANY_SET
         > })
---
- - ['Tuple with bit value = 10', 2]
  - ['Tuple with bit value = 11', 3]
...
tarantool> my_space.index.bitset_index:select(0x02, {
         >   iterator = box.index.BITS_ALL_SET
         > })
---
- - ['Tuple with bit value = 10', 2]
  - ['Tuple with bit value = 11', 3]
...
tarantool> my_space.index.bitset_index:select(0x02, {
         >   iterator = box.index.BITS_ALL_NOT_SET
         > })
---
- - ['Tuple with bit value = 01', 1]
...

Example 2:

tarantool> box.schema.space.create('bitset_example')
tarantool> box.space.bitset_example:create_index('primary')
tarantool> box.space.bitset_example:create_index('bitset',{unique = false, type = 'BITSET', parts = {2,'unsigned'}})
tarantool> box.space.bitset_example:insert{1,1}
tarantool> box.space.bitset_example:insert{2,4}
tarantool> box.space.bitset_example:insert{3,7}
tarantool> box.space.bitset_example:insert{4,3}
tarantool> box.space.bitset_example.index.bitset:select(2, {iterator = 'BITS_ANY_SET'})

The result will be:

---
- - [3, 7]
  - [4, 3]
...

because (7 AND 2) is not equal to 0, and (3 AND 2) is not equal to 0.

Additionally, there exist index iterator operations. They can only be used with code in Lua and C/C++. Index iterators are for traversing indexes one key at a time, taking advantage of features that are specific to an index type. For example, they can be used for evaluating Boolean expressions when traversing BITSET indexes, or for going in descending order when traversing TREE indexes.

Using indexes

Creating an index

It is mandatory to create an index for a space before trying to insert tuples into the space, or select tuples from the space.

The simple index-creation operation is:

box.space.space-name:create_index('index-name')

This creates a unique TREE index on the first field of all tuples (often called «Field#1»), which is assumed to be numeric.

A recommended design pattern for a data model is to base primary keys on the first fields of a tuple. This speeds up tuple comparison due to the specifics of data storage and the way comparisons are arranged in Tarantool.

The simple SELECT request is:

box.space.space-name:select(value)

This looks for a single tuple via the first index. Since the first index is always unique, the maximum number of returned tuples will be 1. You can call select() without arguments, and it will return all tuples. Be careful! Using select() for huge spaces hangs your instance.

An index definition may also include identifiers of tuple fields and their expected types. See allowed indexed field types in section Details about indexed field types:

box.space.space-name:create_index(index-name, {type = 'tree', parts = {{field = 1, type = 'unsigned'}}}

Space definitions and index definitions are stored permanently in Tarantool’s system spaces _space and _index.

Tip

See full information about creating indexes, such as how to create a multikey index, an index using the path option, or how to create a functional index in our reference for space_object:create_index().

Index operations

Index operations are automatic: if a data manipulation request changes a tuple, then it also changes the index keys defined for the tuple.

  1. Create a sample space named bands:

    bands = box.schema.space.create('bands')

  2. Format the created space by specifying field names and types:

    box.space.bands:format({
    { name = 'id', type = 'unsigned' },
    { name = 'band_name', type = 'string' },
    { name = 'year', type = 'unsigned' }
})

  3. Create the primary index (named primary):

    box.space.bands:create_index('primary', { parts = { 'id' } })

    This index is based on the id field of each tuple.

  4. Insert some tuples into the space:

    box.space.bands:insert { 1, 'Roxette', 1986 }
box.space.bands:insert { 2, 'Scorpions', 1965 }
box.space.bands:insert { 3, 'Ace of Base', 1987 }
box.space.bands:insert { 4, 'The Beatles', 1960 }
box.space.bands:insert { 5, 'Pink Floyd', 1965 }
box.space.bands:insert { 6, 'The Rolling Stones', 1962 }
box.space.bands:insert { 7, 'The Doors', 1965 }
box.space.bands:insert { 8, 'Nirvana', 1987 }
box.space.bands:insert { 9, 'Led Zeppelin', 1968 }
box.space.bands:insert { 10, 'Queen', 1970 }

  5. Create secondary indexes:

    -- Create a unique secondary index --
box.space.bands:create_index('band', { parts = { 'band_name' } })

-- Create a non-unique secondary index --
box.space.bands:create_index('year', { parts = { { 'year' } }, unique = false })

  6. Create a multi-part index with two parts:

    box.space.bands:create_index('year_band', { parts = { { 'year' }, { 'band_name' } } })

There are the following SELECT variations:

Tip

You can also add, drop, or alter the definitions at runtime, with some restrictions. Read more about index operations in reference for box.index submodule.

Tuple compression

Enterprise Edition

Tuple compression is available in the Enterprise Edition only.

Tuple compression, introduced in Tarantool Enterprise Edition 2.10.0, aims to save memory space. Typically, it decreases the volume of stored data by 15%. However, the exact volume saved depends on the type of data.

The following compression algorithms are supported:

To learn about the performance costs of each algorithm, check Tuple compression performance.

Tarantool doesn’t compress tuples themselves, just the fields inside these tuples. You can only compress non-indexed fields. Compression works best when JSON is stored in the field.

Примечание

The compress module provides the API for compressing and decompressing data.

Enabling compression for a new space

First, create a space:

box.schema.space.create('bands')

Then, create an index for this space, for example:

box.space.bands:create_index('primary', {parts = {{1, 'unsigned'}}})

Create a format to declare field names and types. In the example below, the band_name and year fields have the zstd and lz4 compression formats, respectively. The first field (id) has the index, so it cannot be compressed.

box.space.bands:format({
           {name = 'id', type = 'unsigned'},
           {name = 'band_name', type = 'string', compression = 'zstd'},
           {name = 'year', type = 'unsigned', compression = 'lz4'}
       })

Now, the new tuples that you add to the space bands will be compressed. When you read a compressed tuple, you do not need to decompress it back yourself.

Checking which fields are compressed

To check which fields in a space are compressed, run space_object:format() on the space. If a field is compressed, the format includes the compression algorithm, for example:

tarantool> box.space.bands:format()
    ---
    - [{'name': 'id', 'type': 'unsigned'},
       {'type': 'string', 'compression': 'zstd', 'name': 'band_name'},
       {'type': 'unsigned', 'compression': 'lz4', 'name': 'year'}]
    ...

Enabling compression for existing spaces

You can enable compression for existing fields. All the tuples added after that will have this field compressed. However, this doesn’t affect the tuples already stored in the space. You need to make the snapshot and restart Tarantool to compress the existing tuples.

Here’s an example of how to compress existing fields:

  1. Create a space without compression and add several tuples:

    box.schema.space.create('bands')

box.space.bands:format({
    { name = 'id', type = 'unsigned' },
    { name = 'band_name', type = 'string' },
    { name = 'year', type = 'unsigned' }
})

box.space.bands:create_index('primary', { parts = { 'id' } })

box.space.bands:insert { 1, 'Roxette', 1986 }
box.space.bands:insert { 2, 'Scorpions', 1965 }
box.space.bands:insert { 3, 'Ace of Base', 1987 }
box.space.bands:insert { 4, 'The Beatles', 1960 }

  2. Suppose that you want fields 2 and 3 to be compressed from now on. To enable compression, change the format as follows:

    local new_format = box.space.bands:format()

new_format[2].compression = 'zstd'
new_format[3].compression = 'lz4'

box.space.bands:format(new_format)

    From now on, all the tuples that you add to the space have fields 2 and 3 compressed.

  3. To finalize the change, create a snapshot by running box.snapshot() and restart Tarantool. As a result, all old tuples will also be compressed in memory during recovery.

Примечание

space:upgrade() provides the ability to enable compression and update the existing tuples in the background. To achieve this, you need to pass a new space format in the format argument of space:upgrade().

Tuple compression performance

Below are the results of a synthetic test that illustrate how tuple compression affects performance. The test was carried out on a simple Tarantool space containing 100,000 tuples, each having a field with a sample JSON roughly 600 bytes large. The test compared the speed of running select and replace operations on uncompressed and compressed data as well as the overall data size of the space. Performance is measured in requests per second.

Compression type select, RPS replace, RPS Space size, bytes
None 4,486k 1,109k 41,168,548
zstd 308k 26k 21,368,548
lz4 1,765k 672k 25,268,548
zlib 325k 107k 20,768,548

Data schema description

In Tarantool, the use of a data schema is optional.

When creating a space, you do not have to define a data schema. In this case, the tuples store random data. This rule does not apply to indexed fields. Such fields must contain data of the same type.

You can define a data schema when creating a space. Read more in the description of the box.schema.space.create() function. If you have already created a space without specifying a data schema, you can do it later using space_object:format().

After the data schema is defined, all the data is validated by type. Before any insert or update, you will get an error if the data types do not match.

We recommend using a data schema because it helps avoid mistakes.

In Tarantool, you can define a data schema in two different ways.

Data schema description in a code file

The code file is usually called init.lua and contains the following schema description:

box.cfg()

users = box.schema.create_space('users', { if_not_exists = true })
users:format({{ name = 'user_id', type = 'number'}, { name = 'fullname', type = 'string'}})

users:create_index('pk', { parts = { { field = 'user_id', type = 'number'}}})

This is quite simple: when you run tarantool, it executes this code and creates a data schema. To run this file, use:

tarantool init.lua

However, it may seem complicated if you do not plan to dive deep into the Lua language and its syntax.

Possible difficulty: the snippet above has a function call with a colon: users:format. It is used to pass the users variable as the first argument of the format function. This is similar to self in object-based languages.

So it might be more convenient for you to describe the data schema with YAML.

Data schema description using the DDL module

The DDL module allows you to describe a data schema in the YAML format in a declarative way.

The schema would look something like this:

spaces:
  users:
    engine: memtx
    is_local: false
    temporary: false
    format:
    - {name: user_id, type: uuid, is_nullable: false}
    - {name: fullname, type: string,  is_nullable: false}
    - {name: bucket_id, type: unsigned, is_nullable: false}
    indexes:
    - name: user_id
      unique: true
      parts: [{path: user_id, type: uuid, is_nullable: false}]
      type: HASH
    - name: bucket_id
      unique: false
      parts: [{path: bucket_id, type: unsigned, is_nullable: false}]
      type: TREE
    sharding_key: [user_id]
    sharding_func: test_module.sharding_func

This alternative is simpler to use, and you do not have to dive deep into Lua.

To use the DDL module, put the following Lua code into the file that you use to run Tarantool. This file is usually called init.lua.

local yaml = require('yaml')
local ddl = require('ddl')

box.cfg{}

local fh = io.open('ddl.yml', 'r')
local schema = yaml.decode(fh:read('*all'))
fh:close()
local ok, err = ddl.check_schema(schema)
if not ok then
    print(err)
end
local ok, err = ddl.set_schema(schema)
if not ok then
    print(err)
end

Предупреждение

It is forbidden to modify the data schema in DDL after it has been applied. For migration, there are different scenarios described in the Migrations section.

Operations

Data operations

The basic data operations supported in Tarantool are:

All of them are implemented as functions in box.space submodule.

Examples:

Summarizing the examples:

See reference on box.space for more details on using data operations.

Примечание

Besides Lua, you can use Perl, PHP, Python or other programming language connectors. The client server protocol is open and documented. See this annotated BNF.

Complexity factors

In reference for box.space and Вложенный модуль box.index submodules, there are notes about which complexity factors might affect the resource usage of each function.

Complexity factor Effect
Index size The number of index keys is the same as the number of tuples in the data set. For a TREE index, if there are more keys, then the lookup time will be greater, although, of course, the effect is not linear. For a HASH index, if there are more keys, then there is more RAM used, but the number of low-level steps tends to remain constant.
Index type Typically, a HASH index is faster than a TREE index if the number of tuples in the space is greater than one.
Number of indexes accessed Ordinarily, only one index is accessed to retrieve one tuple. But to update the tuple, there must be N accesses if the space has N different indexes.
Note regarding storage engine: Vinyl optimizes away such accesses if secondary index fields are unchanged by the update. So, this complexity factor applies only to memtx, since it always makes a full-tuple copy on every update.
Number of tuples accessed A few requests, for example, SELECT, can retrieve multiple tuples. This factor is usually less important than the others.
WAL settings The important setting for the write-ahead log is wal.mode. If the setting causes no writing or delayed writing, this factor is unimportant. If the setting causes every data-change request to wait for writing to finish on a slow device, this factor is more important than all the others.

Примеры CRUD-операций

Using data operations

This section shows basic usage scenarios and typical errors for each data operation in Tarantool: INSERT, DELETE, UPDATE, UPSERT, REPLACE, and SELECT. Before trying out the examples, you need to bootstrap a Tarantool instance as shown below.

-- Create a space --
bands = box.schema.space.create('bands')

-- Specify field names and types --
box.space.bands:format({
    { name = 'id', type = 'unsigned' },
    { name = 'band_name', type = 'string' },
    { name = 'year', type = 'unsigned' }
})

-- Create a primary index --
box.space.bands:create_index('primary', { parts = { 'id' } })

-- Create a unique secondary index --
box.space.bands:create_index('band', { parts = { 'band_name' } })

-- Create a non-unique secondary index --
box.space.bands:create_index('year', { parts = { { 'year' } }, unique = false })

-- Create a multi-part index --
box.space.bands:create_index('year_band', { parts = { { 'year' }, { 'band_name' } } })

INSERT

The space_object.insert method accepts a well-formatted tuple.

-- Insert a tuple with a unique primary key --
tarantool> bands:insert{1, 'Scorpions', 1965}
---
- [1, 'Scorpions', 1965]
...

insert also checks all the keys for duplicates.

-- Try to insert a tuple with a duplicate primary key --
tarantool> bands:insert{1, 'Scorpions', 1965}
---
- error: Duplicate key exists in unique index "primary" in space "bands" with old
    tuple - [1, "Scorpions", 1965] and new tuple - [1, "Scorpions", 1965]
...

-- Try to insert a tuple with a duplicate secondary key --
tarantool> bands:insert{2, 'Scorpions', 1965}
---
- error: Duplicate key exists in unique index "band" in space "bands" with old tuple
    - [1, "Scorpions", 1965] and new tuple - [2, "Scorpions", 1965]
...

-- Insert a second tuple with unique primary and secondary keys --
tarantool> bands:insert{2, 'Pink Floyd', 1965}
---
- [2, 'Pink Floyd', 1965]
...

-- Delete all tuples --
tarantool> bands:truncate()
---
...

DELETE

space_object.delete allows you to delete a tuple identified by the primary key.

-- Insert test data --
tarantool> bands:insert{1, 'Roxette', 1986}
           bands:insert{2, 'Scorpions', 1965}
           bands:insert{3, 'Ace of Base', 1987}
           bands:insert{4, 'The Beatles', 1960}

-- Delete a tuple with an existing key --
tarantool> bands:delete{4}
---
- [4, 'The Beatles', 1960]
...
tarantool> bands:select()
---
- - [1, 'Roxette', 1986]
  - [2, 'Scorpions', 1965]
  - [3, 'Ace of Base', 1987]
...

You can also use index_object.delete to delete a tuple by the specified unique index.

-- Delete a tuple by the primary index --
tarantool> bands.index.primary:delete{3}
---
- [3, 'Ace of Base', 1987]
...
tarantool> bands:select()
---
- - [1, 'Roxette', 1986]
  - [2, 'Scorpions', 1965]
...

-- Delete a tuple by a unique secondary index --
tarantool> bands.index.band:delete{'Scorpions'}
---
- [2, 'Scorpions', 1965]
...
tarantool> bands:select()
---
- - [1, 'Roxette', 1986]
...

-- Try to delete a tuple by a non-unique secondary index --
tarantool> bands.index.year:delete(1986)
---
- error: Get() doesn't support partial keys and non-unique indexes
...
tarantool> bands:select()
---
- - [1, 'Roxette', 1986]
...

-- Try to delete a tuple by a partial key --
tarantool> bands.index.year_band:delete('Roxette')
---
- error: Invalid key part count in an exact match (expected 2, got 1)
...

-- Delete a tuple by a full key --
tarantool> bands.index.year_band:delete{1986, 'Roxette'}
---
- [1, 'Roxette', 1986]
...
tarantool> bands:select()
---
- []
...

-- Delete all tuples --
tarantool> bands:truncate()
---
...

UPDATE

space_object.update allows you to update a tuple identified by the primary key. Similarly to delete, the update method accepts a full key and also an operation to execute.

-- Insert test data --
tarantool> bands:insert{1, 'Roxette', 1986}
           bands:insert{2, 'Scorpions', 1965}
           bands:insert{3, 'Ace of Base', 1987}
           bands:insert{4, 'The Beatles', 1960}

-- Update a tuple with an existing key --
tarantool> bands:update({2}, {{'=', 2, 'Pink Floyd'}})
---
- [2, 'Pink Floyd', 1965]
...

tarantool> bands:select()
---
- - [1, 'Roxette', 1986]
  - [2, 'Pink Floyd', 1965]
  - [3, 'Ace of Base', 1987]
  - [4, 'The Beatles', 1960]
...

index_object.update updates a tuple identified by the specified unique index.

-- Update a tuple by the primary index --
tarantool> bands.index.primary:update({2}, {{'=', 2, 'The Rolling Stones'}})
---
- [2, 'The Rolling Stones', 1965]
...

tarantool> bands:select()
---
- - [1, 'Roxette', 1986]
  - [2, 'The Rolling Stones', 1965]
  - [3, 'Ace of Base', 1987]
  - [4, 'The Beatles', 1960]
...

-- Update a tuple by a unique secondary index --
tarantool> bands.index.band:update({'The Rolling Stones'}, {{'=', 2, 'The Doors'}})
---
- [2, 'The Doors', 1965]
...

tarantool> bands:select()
---
- - [1, 'Roxette', 1986]
  - [2, 'The Doors', 1965]
  - [3, 'Ace of Base', 1987]
  - [4, 'The Beatles', 1960]
...

-- Try to update a tuple by a non-unique secondary index --
tarantool> bands.index.year:update({1965}, {{'=', 2, 'Scorpions'}})
---
- error: Get() doesn't support partial keys and non-unique indexes
...
tarantool> bands:select()
---
- - [1, 'Roxette', 1986]
  - [2, 'The Doors', 1965]
  - [3, 'Ace of Base', 1987]
  - [4, 'The Beatles', 1960]
...

-- Delete all tuples --
tarantool> bands:truncate()
---
...

UPSERT

space_object.upsert updates an existing tuple or inserts a new one:

  • If the existing tuple is found by the primary key, Tarantool applies the update operation to this tuple and ignores the new tuple.
  • If no existing tuple is found, Tarantool inserts the new tuple and ignores the update operation.
tarantool> bands:insert{1, 'Scorpions', 1965}
---
- [1, 'Scorpions', 1965]
...
-- As the first argument, upsert accepts a tuple, not a key --
tarantool> bands:upsert({2}, {{'=', 2, 'Pink Floyd'}})
---
- error: Tuple field 2 (band_name) required by space format is missing
...
tarantool> bands:select()
---
- - [1, 'Scorpions', 1965]
...
tarantool> bands:delete(1)
---
- [1, 'Scorpions', 1965]
...

upsert acts as insert when no existing tuple is found by the primary key.

tarantool> bands:upsert({1, 'Scorpions', 1965}, {{'=', 2, 'The Doors'}})
---
...
-- As you can see, {1, 'Scorpions', 1965} is inserted, --
-- and the update operation is not applied. --
tarantool> bands:select()
---
- - [1, 'Scorpions', 1965]
...

-- upsert with the same primary key but different values in other fields --
-- applies the update operation and ignores the new tuple. --
tarantool> bands:upsert({1, 'Scorpions', 1965}, {{'=', 2, 'The Doors'}})
---
...
tarantool> bands:select()
---
- - [1, 'The Doors', 1965]
...

upsert searches for the existing tuple by the primary index, not by the secondary index. This can lead to a duplication error if the tuple violates a secondary index uniqueness.

tarantool> bands:upsert({2, 'The Doors', 1965}, {{'=', 2, 'Pink Floyd'}})
---
- error: Duplicate key exists in unique index "band" in space "bands" with old tuple
    - [1, "The Doors", 1965] and new tuple - [2, "The Doors", 1965]
...
tarantool> bands:select()
---
- - [1, 'The Doors', 1965]
...

-- This works if uniqueness is preserved. --
tarantool> bands:upsert({2, 'The Beatles', 1960}, {{'=', 2, 'Pink Floyd'}})
---
...
tarantool> bands:select()
---
- - [1, 'The Doors', 1965]
  - [2, 'The Beatles', 1960]
...

-- Delete all tuples --
tarantool> bands:truncate()
---
...

REPLACE

space_object.replace accepts a well-formatted tuple and searches for the existing tuple by the primary key of the new tuple:

  • If the existing tuple is found, Tarantool deletes it and inserts the new tuple.
  • If no existing tuple is found, Tarantool inserts the new tuple.
tarantool> bands:replace{1, 'Scorpions', 1965}
---
- [1, 'Scorpions', 1965]
...
tarantool> bands:select()
---
- - [1, 'Scorpions', 1965]
...
tarantool> bands:replace{1, 'The Beatles', 1960}
---
- [1, 'The Beatles', 1960]
...
tarantool> bands:select()
---
- - [1, 'The Beatles', 1960]
...
tarantool> bands:truncate()
---
...

replace can violate unique constraints, like upsert does.

tarantool> bands:insert{1, 'Scorpions', 1965}
- [1, 'Scorpions', 1965]
...
tarantool> bands:insert{2, 'The Beatles', 1960}
---
- [2, 'The Beatles', 1960]
...
tarantool> bands:replace{2, 'Scorpions', 1965}
---
- error: Duplicate key exists in unique index "band" in space "bands" with old tuple
    - [1, "Scorpions", 1965] and new tuple - [2, "Scorpions", 1965]
...
tarantool> bands:truncate()
---
...

SELECT

The space_object.select request searches for a tuple or a set of tuples in the given space by the primary key. To search by the specified index, use index_object.select. These methods work with any keys, including unique and non-unique, full and partial. If a key is partial, select searches by all keys where the prefix matches the specified key part.

tarantool> bands:insert{1, 'Roxette', 1986}
           bands:insert{2, 'Scorpions', 1965}
           bands:insert{3, 'The Doors', 1965}
           bands:insert{4, 'The Beatles', 1960}

tarantool> bands:select(1)
---
- - [1, 'Roxette', 1986]
...

tarantool> bands:select()
---
- - [1, 'Roxette', 1986]
  - [2, 'Scorpions', 1965]
  - [3, 'The Doors', 1965]
  - [4, 'The Beatles', 1960]
...

tarantool> bands.index.primary:select(2)
---
- - [2, 'Scorpions', 1965]
...

tarantool> bands.index.band:select('The Doors')
---
- - [3, 'The Doors', 1965]
...

tarantool> bands.index.year:select(1965)
---
- - [2, 'Scorpions', 1965]
  - [3, 'The Doors', 1965]
...

Using box.space functions to read _space tuples

This example illustrates how to look at all the spaces, and for each display: approximately how many tuples it contains, and the first field of its first tuple. The function uses the Tarantool’s box.space functions len() and pairs(). The iteration through the spaces is coded as a scan of the _space system space, which contains metadata. The third field in _space contains the space name, so the key instruction space_name = v[3] means space_name is the space_name field in the tuple of _space that we’ve just fetched with pairs(). The function returns a table:

function example()
  local tuple_count, space_name, line
  local ta = {}
  for k, v in box.space._space:pairs() do
    space_name = v[3]
    if box.space[space_name].index[0] ~= nil then
      tuple_count = '1 or more'
    else
      tuple_count = '0'
    end
    line = space_name .. ' tuple_count =' .. tuple_count
    if tuple_count == '1 or more' then
      for k1, v1 in box.space[space_name]:pairs() do
        line = line .. '. first field in first tuple = ' .. v1[1]
        break
      end
    end
    table.insert(ta, line)
  end
  return ta
end

The output below shows what happens if you invoke this function:

tarantool> example()
---
- - _schema tuple_count =1 or more. first field in first tuple = cluster
  - _space tuple_count =1 or more. first field in first tuple = 272
  - _vspace tuple_count =1 or more. first field in first tuple = 272
  - _index tuple_count =1 or more. first field in first tuple = 272
  - _vindex tuple_count =1 or more. first field in first tuple = 272
  - _func tuple_count =1 or more. first field in first tuple = 1
  - _vfunc tuple_count =1 or more. first field in first tuple = 1
  - _user tuple_count =1 or more. first field in first tuple = 0
  - _vuser tuple_count =1 or more. first field in first tuple = 0
  - _priv tuple_count =1 or more. first field in first tuple = 1
  - _vpriv tuple_count =1 or more. first field in first tuple = 1
  - _cluster tuple_count =1 or more. first field in first tuple = 1
...

Using box.space functions to organize a _space tuple

This examples shows how to display field names and field types of a system space – using metadata to find metadata.

Для начала: как можно сделать выборку кортежа из _space, который описывает _space?

A simple way is to look at the constants in box.schema, which shows that there is an item named SPACE_ID == 288, so these statements retrieve the correct tuple:

box.space._space:select{ 288 }
-- или --
box.space._space:select{ box.schema.SPACE_ID }

Another way is to look at the tuples in box.space._index, which shows that there is a secondary index named „name“ for a space number 288, so this statement also retrieve the correct tuple:

box.space._space.index.name:select{ '_space' }

Однако непросто прочитать информацию из полученного кортежа:

tarantool> box.space._space.index.name:select{'_space'}
---
- - [280, 1, '_space', 'memtx', 0, {}, [{'name': 'id', 'type': 'num'}, {'name': 'owner',
        'type': 'num'}, {'name': 'name', 'type': 'str'}, {'name': 'engine', 'type': 'str'},
      {'name': 'field_count', 'type': 'num'}, {'name': 'flags', 'type': 'str'}, {
        'name': 'format', 'type': '*'}]]
...

Информация подается бессистемно, поскольку по формату поле №7 содержит рекомендованные имена и типы данных. Как же получить эти данные? Поскольку очевидно, что поле №7 представляет собой ассоциативный массив, цикл for проведет организацию данных:

tarantool> do
         >   local tuple_of_space = box.space._space.index.name:get{'_space'}
         >   for _, field in ipairs(tuple_of_space[7]) do
         >     print(field.name .. ', ' .. field.type)
         >   end
         > end
id, num
owner, num
name, str
engine, str
field_count, num
flags, str
format, *
---
...

Using sequences

A sequence is a generator of ordered integer values.

As with spaces and indexes, you should specify the sequence name and let Tarantool generate a unique numeric identifier (sequence ID).

As well, you can specify several options when creating a new sequence. The options determine the values that are generated whenever the sequence is used.

Options for box.schema.sequence.create()

Option name Type and meaning Default Examples
start Integer. The value to generate the first time a sequence is used 1 start=0
min Integer. Values smaller than this cannot be generated 1 min=-1000
max Integer. Values larger than this cannot be generated 9223372036854775807 max=0
cycle Boolean. Whether to start again when values cannot be generated false cycle=true
cache Integer. The number of values to store in a cache 0 cache=0
step Integer. What to add to the previous generated value, when generating a new value 1 step=-1
if_not_exists Boolean. If this is true and a sequence with this name exists already, ignore other options and use the existing values false if_not_exists=true

Once a sequence exists, it can be altered, dropped, reset, forced to generate the next value, or associated with an index.

Associating a sequence with an index

First, create a sequence:

-- Create a sequence --
box.schema.sequence.create('id_seq',{min=1000, start=1000})
--[[
---
- step: 1
  id: 1
  min: 1000
  cache: 0
  uid: 1
  cycle: false
  name: id_seq
  start: 1000
  max: 9223372036854775807
...
--]]

The result shows that the new sequence has all default values, except for the two that were specified, min and start.

Get the next value from the sequence by calling the next() function:

-- Get the next item --
box.sequence.id_seq:next()
--[[
---
- 1000
...
--]]

The result is the same as the start value. The next call increases the value by one (the default sequence step).

Create a space and specify that its primary key should be generated from the sequence:

-- Create a space --
box.schema.space.create('customers')

-- Create an index that uses the sequence --
box.space.customers:create_index('primary',{ sequence = 'id_seq' })
--[[
---
- parts:
  - type: unsigned
    is_nullable: false
    fieldno: 1
  sequence_id: 1
  id: 0
  space_id: 513
  unique: true
  hint: true
  type: TREE
  name: primary
  sequence_fieldno: 1
...
--]]

Insert a tuple without specifying a value for the primary key:

-- Insert a tuple without the primary key value --
box.space.customers:insert{ nil, 'Adams' }
--[[
---
- [1001, 'Adams']
...
--]]

The result is a new tuple where the first field is assigned the next value from the sequence. This arrangement, where the system automatically generates the values for a primary key, is sometimes called «auto-incrementing» or «identity».

For syntax and implementation details, see the reference for box.schema.sequence.

Migrations

Migration refers to any change in a data schema: adding or removing a field, creating or dropping an index, changing a field format, and so on. Space creation is also a migration. Using migrations, you can track the evolution of your data schema since its initial state. In Tarantool, migrations are presented as Lua code that alters the data schema using the built-in Lua API.

There are two types of migrations:

Simple migrations

There are two types of schema migration that do not require data migration:

Complex migrations

Other types of migrations are more complex and require additional actions to maintain data consistency.

Migrations are possible in two cases:

For the first case, it is enough to write and test the migration code. The most difficult task is to migrate data when there are active clients. You should keep it in mind when you initially design the data schema.

We identify the following problems if there are active clients:

These issues may or may not be relevant depending on your application and its availability requirements.

Tarantool offers the following features that make migrations easier and safer:

Applying migrations

The migration code is executed on a running Tarantool instance. Important: no method guarantees you transactional application of migrations on the whole cluster.

Method 1: include migrations in the application code

This is quite simple: when you reload the code, the data is migrated at the right moment, and the database schema is updated. However, this method may not work for everyone. You may not be able to restart Tarantool or update the code using the hot-reload mechanism.

Method 2: the tt utility

Connect to the necessary instance using tt connect.

$ tt connect admin:password@localhost:3301

You can also connect to the instance and execute the migration script in a single call:

$ tt connect admin:password@localhost:3301 -f 0001-delete-space.lua

Centralized migration management

Enterprise Edition

Centralized migration management is available in the Enterprise Edition only.

Tarantool EE offers a mechanism for centralized migration management in replication clusters that use etcd as a configuration storage. The mechanism uses the same etcd storage to store migrations and applies them across the entire Tarantool cluster. This ensures migration consistency in the cluster and enables migration history tracking.

The centralized migration management mechanism is implemented in the Enterprise version of the tt utility and in Tarantool Cluster Manager.

To learn how to manage migrations in Tarantool EE clusters from the command line, see Centralized migrations with tt. To learn how to use the mechanism from the TCM web interface, see the Performing migrations TCM documentation page.

Centralized migrations with tt

Example on GitHub: migrations

In this section, you learn to use the centralized migration management mechanism implemented in the Enterprise Edition of the tt utility.

The section includes the following tutorials:

See also:

Basic tt migrations tutorial

Example on GitHub: migrations

In this tutorial, you learn to define the cluster data schema using the centralized migration management mechanism implemented in the Enterprise Edition of the tt utility.

Prerequisites

Before starting this tutorial:

Preparing a cluster

The centralized migration mechanism works with Tarantool EE clusters that:

Setting up etcd

First, start up an etcd instance to use as a configuration storage:

$ etcd

etcd runs on the default port 2379.

Optionally, enable etcd authentication by executing the following script:

#!/usr/bin/env bash

etcdctl user add root:topsecret
etcdctl role add app_config_manager
etcdctl role grant-permission app_config_manager --prefix=true readwrite /myapp/
etcdctl user add app_user:config_pass
etcdctl user grant-role app_user app_config_manager
etcdctl auth enable

It creates an etcd user app_user with read and write permissions to the /myapp prefix, in which the cluster configuration will be stored. The user’s password is config_pass.

Примечание

If you don’t enable etcd authentication, make tt migrations calls without the configuration storage credentials.

Creating a cluster

  1. Initialize a tt environment:

    $ tt init

  2. In the instances.enabled directory, create the myapp directory.

  3. Go to the instances.enabled/myapp directory and create application files:

  • instances.yml:
router-001-a:
storage-001-a:
storage-001-b:
storage-002-a:
storage-002-b:
  • config.yaml:
config:
  etcd:
    endpoints:
    - http://localhost:2379
    prefix: /myapp/
    username: app_user
    password: config_pass
    http:
      request:
        timeout: 3

  • myapp-scm-1.rockspec:

    package = 'myapp'
version = 'scm-1'

source  = {
    url = '/dev/null',
}

dependencies = {
    'crud == 1.5.2',
}

build = {
    type = 'none';
}

  1. Create the source.yaml with a cluster configuration to publish to etcd:

    Примечание

    This configuration describes a typical CRUD-enabled sharded cluster with one router and two storage replica sets, each including one master and one read-only replica.

    credentials:
  users:
    client:
      password: 'secret'
      roles: [super]
    replicator:
      password: 'secret'
      roles: [replication]
    storage:
      password: 'secret'
      roles: [sharding]

iproto:
  advertise:
    peer:
      login: replicator
    sharding:
      login: storage

sharding:
  bucket_count: 3000

groups:
  routers:
    sharding:
      roles: [router]
    roles: [roles.crud-router]
    replicasets:
      router-001:
        instances:
          router-001-a:
            iproto:
              listen:
              - uri: localhost:3301
              advertise:
                client: localhost:3301
  storages:
    sharding:
      roles: [storage]
    roles: [roles.crud-storage]
    replication:
      failover: manual
    replicasets:
      storage-001:
        leader: storage-001-a
        instances:
          storage-001-a:
            iproto:
              listen:
                - uri: localhost:3302
              advertise:
                client: localhost:3302
          storage-001-b:
            iproto:
              listen:
              - uri: localhost:3303
              advertise:
                client: localhost:3303
      storage-002:
        leader: storage-002-a
        instances:
          storage-002-a:
            iproto:
              listen:
              - uri: localhost:3304
              advertise:
                client: localhost:3304
          storage-002-b:
            iproto:
              listen:
              - uri: localhost:3305
              advertise:
                client: localhost:3305

  2. Publish the configuration to etcd:

    $ tt cluster publish "http://app_user:config_pass@localhost:2379/myapp/" source.yaml

The full cluster code is available on GitHub here: migrations.

Building and starting the cluster

  1. Build the application:

    $ tt build myapp

  2. Start the cluster:

    $ tt start myapp

    To check that the cluster is up and running, use tt status:

    $ tt status myapp

  3. Bootstrap vshard in the cluster:

    $ tt replicaset vshard bootstrap myapp

Writing migrations

To perform migrations in the cluster, write them in Lua and publish to the cluster’s etcd configuration storage.

Each migration file must return a Lua table with one object named apply. This object has one field – scenario – that stores the migration function:

local function apply_scenario()
    -- migration code
end

return {
    apply = {
        scenario = apply_scenario,
    },
}

The migration unit is a single file: its scenario is executed as a whole. An error that happens in any step of the scenario causes the entire migration to fail.

Migrations are executed in the lexicographical order. Thus, it’s convenient to use filenames that start with ordered numbers to define the migrations order, for example:

000001_create_space.lua
000002_create_index.lua
000003_alter_space.lua

The default location where tt searches for migration files is /migrations/scenario. Create this subdirectory inside the tt environment. Then, create two migration files:

Publishing migrations

To publish migrations to the etcd configuration storage, run tt migrations publish:

$ tt migrations publish "http://app_user:config_pass@localhost:2379/myapp"
   • 000001_create_writes_space.lua: successfully published to key "000001_create_writes_space.lua"
   • 000002_create_writers_index.lua: successfully published to key "000002_create_writers_index.lua"

Applying migrations

To apply published migrations to the cluster, run tt migrations apply providing a cluster user’s credentials:

$ tt migrations apply "http://app_user:config_pass@localhost:2379/myapp" \
                      --tarantool-username=client --tarantool-password=secret

Важно

The cluster user must have enough access privileges to execute the migrations code.

The output should look as follows:

• router-001:
•     000001_create_writes_space.lua: successfully applied
•     000002_create_writers_index.lua: successfully applied
• storage-001:
•     000001_create_writes_space.lua: successfully applied
•     000002_create_writers_index.lua: successfully applied
• storage-002:
•     000001_create_writes_space.lua: successfully applied
•     000002_create_writers_index.lua: successfully applied

The migrations are applied on all replica set leaders. Read-only replicas receive the changes from the corresponding replica set leaders.

Check the migrations status with tt migration status:

$ tt migrations status "http://app_user:config_pass@localhost:2379/myapp" \
                       --tarantool-username=client --tarantool-password=secret
   • migrations centralized storage scenarios:
   •   000001_create_writes_space.lua
   •   000002_create_writers_index.lua
   • migrations apply status on Tarantool cluster:
   •   router-001:
   •     000001_create_writes_space.lua: APPLIED
   •     000002_create_writers_index.lua: APPLIED
   •   storage-001:
   •     000001_create_writes_space.lua: APPLIED
   •     000002_create_writers_index.lua: APPLIED
   •   storage-002:
   •     000001_create_writes_space.lua: APPLIED
   •     000002_create_writers_index.lua: APPLIED

To make sure that the space and indexes are created in the cluster, connect to the router instance and retrieve the space information:

$ tt connect myapp:router-001-a

myapp:router-001-a> require('crud').schema('writers')
---
- indexes:
    0:
      unique: true
      parts:
      - fieldno: 1
        type: number
        exclude_null: false
        is_nullable: false
      id: 0
      type: TREE
      name: primary
    2:
      unique: true
      parts:
      - fieldno: 4
        type: number
        exclude_null: false
        is_nullable: false
      id: 2
      type: TREE
      name: age
  format: [{'name': 'id', 'type': 'number'}, {'type': 'number', 'name': 'bucket_id',
      'is_nullable': true}, {'name': 'name', 'type': 'string'}, {'name': 'age', 'type': 'number'}]
...

Next steps

Learn to write and perform data migration in Data migrations with space.upgrade().

Data migrations with space.upgrade()

Example on GitHub: migrations

In this tutorial, you learn to write migrations that include data migration using the space.upgrade() function.

Prerequisites

Before starting this tutorial, complete the Basic tt migrations tutorial. As a result, you have a sharded Tarantool EE cluster that uses an etcd-based configuration storage. The cluster has a space with two indexes.

Writing a complex migration

Complex migrations require data migration along with schema migration. Connect to the router instance and insert some tuples into the space before proceeding to the next steps.

$ tt connect myapp:router-001-a

myapp:router-001-a> require('crud').insert_object_many('writers', {
    {id = 1, name = 'Haruki Murakami', age = 75},
    {id = 2, name = 'Douglas Adams', age = 49},
    {id = 3, name = 'Eiji Mikage', age = 41},
}, {noreturn = true})

The next migration changes the space format incompatibly: instead of one name field, the new format includes two fields first_name and last_name. To apply this migration, you need to change each tuple’s structure preserving the stored data. The space.upgrade function helps with this task.

Create a new file 000003_alter_writers_space.lua in /migrations/scenario. Prepare its initial structure the same way as in previous migrations:

local function apply_scenario()
--  migration code
end
return {
    apply = {
        scenario = apply_scenario,
    },
}

Start the migration function with the new format description:

local function apply_scenario()
    local space = box.space['writers']
    local new_format = {
        {name = 'id', type = 'number'},
        {name = 'bucket_id', type = 'number'},
        {name = 'first_name', type = 'string'},
        {name = 'last_name', type = 'string'},
        {name = 'age', type = 'number'},
    }
    box.space.writers.index.age:drop()

Примечание

box.space.writers.index.age:drop() drops an existing index. This is done because indexes rely on field numbers and may break during this format change. If you need the age field indexed, recreate the index after applying the new format.

Next, create a stored function that transforms tuples to fit the new format. In this case, the function extracts the first and the last name from the name field and returns a tuple of the new format:

box.schema.func.create('_writers_split_name', {
    language = 'lua',
    is_deterministic = true,
    body = [[
    function(t)
        local name = t[3]

        local split_data = {}
        local split_regex = '([^%s]+)'
        for v in string.gmatch(name, split_regex) do
            table.insert(split_data, v)
        end

        local first_name = split_data[1]
        assert(first_name ~= nil)

        local last_name = split_data[2]
        assert(last_name ~= nil)

        return {t[1], t[2], first_name, last_name, t[4]}
    end
    ]],
})

Finally, call space:upgrade() with the new format and the transformation function as its arguments. Here is the complete migration code:

local function apply_scenario()
    local space = box.space['writers']
    local new_format = {
        {name = 'id', type = 'number'},
        {name = 'bucket_id', type = 'number'},
        {name = 'first_name', type = 'string'},
        {name = 'last_name', type = 'string'},
        {name = 'age', type = 'number'},
    }
    box.space.writers.index.age:drop()

    box.schema.func.create('_writers_split_name', {
        language = 'lua',
        is_deterministic = true,
        body = [[
        function(t)
            local name = t[3]

            local split_data = {}
            local split_regex = '([^%s]+)'
            for v in string.gmatch(name, split_regex) do
                table.insert(split_data, v)
            end

            local first_name = split_data[1]
            assert(first_name ~= nil)

            local last_name = split_data[2]
            assert(last_name ~= nil)

            return {t[1], t[2], first_name, last_name, t[4]}
        end
        ]],
    })

    local future = space:upgrade({
        func = '_writers_split_name',
        format = new_format,
    })

    future:wait()
end

return {
    apply = {
        scenario = apply_scenario,
    },
}

Learn more about space.upgrade() in Upgrading space schema.

Publishing the migration

Publish the new migration to etcd.

$ tt migrations publish "http://app_user:config_pass@localhost:2379/myapp" \
                        migrations/scenario/000003_alter_writers_space.lua

Примечание

You can also publish all migrations from the default location /migrations/scenario. All other migrations stored in this directory are already published, so tt skips them.

$ tt migrations publish "http://app_user:config_pass@localhost:2379/myapp"

Applying the migration

Apply the published migrations:

$ tt migrations apply "http://app_user:config_pass@localhost:2379/myapp" \
                      --tarantool-username=client --tarantool-password=secret

Connect to the router instance and check that the space and its tuples have the new format:

$ tt connect myapp:router-001-a

myapp:router-001-a> require('crud').get('writers', 2)
---
- rows: [2, 401, 'Douglas', 'Adams', 49]
  metadata: [{'name': 'id', 'type': 'number'}, {'name': 'bucket_id', 'type': 'number'},
    {'name': 'first_name', 'type': 'string'}, {'name': 'last_name', 'type': 'string'},
    {'name': 'age', 'type': 'number'}]
- null
...

Next steps

Learn to use migrations for data schema definition on new instances added to the cluster in Extending the cluster.

Extending the cluster

Example on GitHub: migrations

In this tutorial, you learn how to consistently define the data schema on newly added cluster instances using the centralized migration management mechanism.

Prerequisites

Before starting this tutorial, complete the Basic tt migrations tutorial and Data migrations with space.upgrade(). As a result, you have a sharded Tarantool EE cluster that uses an etcd-based configuration storage. The cluster has a space with two indexes.

Extending the cluster

Having all migrations in a centralized etcd storage, you can extend the cluster and consistently define the data schema on new instances on the fly.

Add one more storage replica set to the cluster. To do this, edit the cluster files in instances.enabled/myapp:

Publish the new cluster configuration to etcd:

$ tt cluster publish "http://app_user:config_pass@localhost:2379/myapp/" source.yaml

Run tt start to start up the new instances:

$ tt start myapp
   • The instance myapp:router-001-a (PID = 61631) is already running.
   • The instance myapp:storage-001-a (PID = 61632) is already running.
   • The instance myapp:storage-001-b (PID = 61634) is already running.
   • The instance myapp:storage-002-a (PID = 61639) is already running.
   • The instance myapp:storage-002-b (PID = 61640) is already running.
   • Starting an instance [myapp:storage-003-a]...
   • Starting an instance [myapp:storage-003-b]...

Now the cluster contains three storage replica sets.

Applying migrations to the new replica set

The new replica set – storage-003– is just started and has no data schema yet. Apply all stored migrations to the cluster to load the same data schema to the new replica set:

$ tt migrations apply "http://app_user:config_pass@localhost:2379/myapp" \
                      --tarantool-username=client --tarantool-password=secret
                      --replicaset=storage-003

Примечание

You can also apply migrations without specifying the replica set. All published migrations are already applied on other replica sets, so tt skips the operation on them.

$ tt migrations apply "http://app_user:config_pass@localhost:2379/myapp" \
                      --tarantool-username=client --tarantool-password=secret

To make sure that the space exists on the new instances, connect to storage-003-a and check box.space.writers:

$ tt connect myapp:storage-003-a

myapp:storage-003-a> box.space.writers ~= nil
---
- true
...

Troubleshooting migrations

The centralized migrations mechanism allows troubleshooting migration issues using dedicated tt migration options. When troubleshooting migrations, remember that any unfinished or failed migration can bring the data schema into to inconsistency. Additional steps may be needed to fix this.

Предупреждение

The options used for migration troubleshooting can cause migration inconsistency in the cluster. Use them only for local development and testing purposes.

Incorrect migration published

If an incorrect migration was published to etcd but wasn’t applied yet, fix the migration file and publish it again with the --overwrite option:

$ tt migrations publish "http://app_user:config_pass@localhost:2379/myapp" \
                        000001_create_space.lua --overwrite

If the migration that needs a fix isn’t the last in the lexicographical order, add also --ignore-order-violation:

$ tt migrations publish "http://app_user:config_pass@localhost:2379/myapp" \
                        000001_create_space.lua --overwrite --ignore-order-violation

If a migration was published by mistake and wasn’t applied yet, you can delete it from etcd using tt migrations remove:

$ tt migrations remove "http://app_user:config_pass@localhost:2379/myapp" \
                    --migration 000003_not_needed.lua

Incorrect migration applied

If the migration is already applied, publish the fixed version and apply it with the --force-reapply option:

$ tt migrations apply "http://app_user:config_pass@localhost:2379/myapp" \
                      --tarantool-username=client --tarantool-password=secret \
                      --force-reapply

If execution of the incorrect migration version has failed, you may also need to add the --ignore-preceding-status option:

When you reapply a migration, tt checks the statuses of preceding migrations to ensure consistency. To skip this check, add the --ignore-preceding-status option:

$ tt migrations apply "http://app_user:config_pass@localhost:2379/myapp" \
                      --tarantool-username=client --tarantool-password=secret \
                      --migration=00003_alter_space.lua
                      --force-reapply --ignore-preceding-status

Migration execution takes too long

To interrupt migration execution on the cluster, use tt migrations stop:

$ tt migrations stop "http://app_user:config_pass@localhost:2379/myapp" \
                      --tarantool-username=client --tarantool-password=secret

You can adjust the maximum migration execution time using the --execution-timeout option of tt migrations apply:

$ tt migrations apply "http://app_user:config_pass@localhost:2379/myapp" \
                      --tarantool-username=client --tarantool-password=secret \
                      --execution-timeout=60

Примечание

If a migration timeout is reached, you may need to call tt migrations stop to cancel requests that were sent when applying migrations.

Upgrading space schema

Enterprise Edition

space:upgrade() is available in the Enterprise Edition only.

In Tarantool, migration refers to any change in a data schema, for example, creating an index, adding a field, or changing a field format. If you need to change a data schema, there are several possible cases:

To solve the task of migrating the data, you can:

Space upgrade overview

The space:upgrade() feature allows users to upgrade the format of a space and the tuples stored in it without blocking the database.

How to apply space upgrade

First, specify an upgrade function – a function that will convert the tuples in the space to a new format. The requirements for this function are listed below.

  • The upgrade function takes two arguments. The first argument is a tuple to be upgraded. The second one is optional. It contains some additional information stored in plain Lua object. If omitted, the second argument is nil.
  • The function returns a new tuple or a Lua table. For example, it can add a new field to the tuple. The new tuple must conform to the new space format set by the upgrade operation.
  • The function should be registered with box.schema.func.create. It should also be stored, deterministic, and written in Lua.
  • The function should not change the primary key of the tuple.
  • The function should be idempotent: f(f(t)) = f(t). This is necessary because the function is applied to all tuples returned to the user, and some of them may have already been upgraded in the background.

Then define a new space format. This step is optional. However, it could be useful if, for example, you want to add a new column with data. For details, check the Usage Example section.

The next optional step is to choose an upgrade mode. There are three modes: upgrade, dryrun, and dryrun+upgrade. The default value is upgrade. To check an upgrade function without applying any changes, choose the dryrun mode. To run a space upgrade without testing the function, pick the upgrade mode. If you want to apply both the test and the actual upgrade, use the dryrun+upgrade option. For details, see the Upgrade Modes section.

How the upgrade works

The user defines an upgrade function. Each tuple of the chosen space is passed through the function. The function converts the tuple from the old format to a new one. The function is applied to all tuples stored in the space in the background. Besides, the function is applied to all tuples returned to the user via the box API (for example, select, get). Therefore, it appears that the space upgrades instantly.

Keep in mind that space:upgrade differs from the space_object:format() in the following ways:

Difference space:upgrade() space:format()
Non-blocking Yes. It returns tuples in the new format, whether or not they have already been converted. Yes.
Set a format incompatible with the current one Yes. Works for non-indexed field types only. No, only expand the format in a compatible way.
Visibility of changes Immediately. All changes are visible and replicated immediately. New data should conform to the new format immediately after the call. After data validation. Data validation starts in the background, it does not block the database. Inserting data incompatible with the new format is allowed before validation is completed – in this case space.format fails.
Cancel (error/restart) Writes the state to the system table. Restart: the operation continues. Error: the operation should be restarted manually, any other attempt to change the table fails. Leaves no traces.
Set the upgrade function Yes. The upgrade may take a while to traverse the space and transform tuples. No.

Примечание

At the moment, the feature is not supported for vinyl spaces.

User API

The space:upgrade() method is added to the space object:

space:upgrade({func[, arg, format, mode, is_async]}])
Параметры:
  • func (string/integer) – upgrade function name (string) or ID (integer). For details, see the upgrade function requirements section.
  • arg – additional information passed to the upgrade function in the second argument. The option accepts any Lua value that can be encoded in MsgPack, which means that the msgpack.encode(arg) should succeed. For example, one can pass a scalar or a Lua table. The default value is nil.
  • format (map) – new space format. The requirements for this are the same as for any other space:format(). If the field is omitted, the space format will remain the same as before the upgrade.
  • mode (string) – upgrade mode. Possible values: upgrade, dryrun, dryrun+upgrade. The default value is upgrade.
  • is_async (boolean) – the flag indicates whether to wait until the upgrade operation is complete before exiting the function. The default value is false – the function is blocked until the upgrade operation is finished.
Return:

object describing the status of the operation (also known as future). The methods of the object are described below.
object future_object
future_object:info(dryrun, status, func, arg, owner, error, progress)

Shows information about the state of the upgrade operation.

Параметры:
  • dryrun (boolean) – dry run mode flag. Possible values: true for a dry run, nil for an actual upgrade.
  • status (string) – upgrade status. Possible values: inprogress, waitrw, error, replica, done.
  • func (string/integer) – name of the upgrade function. It is the same as passed to the space:upgrade method. The field is nil if the status is done.
  • arg – additional information passed to the upgrade function. It is the same as for the space:upgrade method. The field is nil if it is omitted in the space:upgrade.
  • owner (string) – UUID of the instance running the upgrade (see box.info.uuid). The field is nil if the status is done.
  • error (string) – error message if the status is error, otherwise nil.
  • progress (string) – completion percentage if the status is inprogress/waitrw, otherwise nil.
Return:

a table with information about the state of the upgrade operation
Rtype:

table

The fields can also be accessed directly, without calling the info() method. For example, future.status is the same as future:info().status.

future_object:wait([timeout])

Waits until the upgrade operation is completed or a timeout occurs. An operation is considered completed if its status is done or error.

Параметры:
  • timeout (double) – if the timeout argument is omitted, the method waits as long as it takes.
Return:

returns true if the operation has been completed, false on timeout
Rtype:

boolean
future_object:cancel()

Cancels the upgrade operation if it is currently running. Otherwise, an exception is thrown. A canceled upgrade operation completes with an error.

Return:none
Rtype:void

Running space:upgrade() with is_async = false or the is_async field not set is equal to:

local future = space:upgrade({func = 'my_func', is_async = true})
future:wait()
return future

If called without arguments, space:upgrade() returns a future object for the active upgrade operation. If there is none, it returns nil.

Upgrade modes

There are three upgrade modes: dryrun, dryrun+upgrade, and upgrade. Regardless of the mode selected, the upgrade does not block execution. Once in a while, the background fiber commits the upgraded tuples and yields.

Calling space:upgrade without arguments always returns the current state of the space upgrade, never the state of a dry run. If there is a dry run working in the background, space:upgrade will still return nil. Unlike an actual space upgrade, the future object returned by a dry run upgrade can’t be recovered if it is lost. So a dry run is aborted if it is garbage collected.

Предупреждение

In dryrun+upgrade mode: if the future object is garbage collected by Lua before the end of the dry run and the start of the upgrade, then the dry run will be canceled, and no upgrade will be started.

Upgrade modes:

States

An upgrade operation has one of the following upgrade states:

../../../../_images/ddl-state.png

Interaction with alter

While a space upgrade is in progress, the space can’t be altered or dropped. The attempt to do that will throw an exception. Restarting an upgrade is allowed in case the currently running upgrade is canceled or completed with an error. It means the manual restart is possible if the upgrade operation is in the error state.

If a space upgrade was canceled or failed with an error, the space can’t be altered or dropped. The only option is to restart the upgrade using a different upgrade function or format.

Interaction with recovery

The space upgrade state is persisted. It is stored in the _space system table. If an instance with a space upgrade in progress (inprogress state) is shut down, it restarts the space upgrade after recovery. If a space upgrade fails (switches to the error state), it remains in the error state after recovery.

Interaction with replication

The changes made to a space by a space upgrade are replicated. Just as on the instance where the upgrade is performed, the upgrade function is applied to all tuples returned to the user on the replicas. However, the upgrade operation is not performed on the replicas in the background. The replicas wait for the upgrade operation to complete on the master. They can’t alter or drop the space. Normally, they can’t cancel or restart the upgrade operation either.

There is an emergency exception when the master is permanently dead. It is possible to restart a space upgrade that started on another instance. The restart is possible if the upgrade owner UUID (see the owner field) has been deleted from the _cluster system table.

Примечание

Except the dryrun mode, the upgrade can only be performed on the master. If the instance is no longer the master, the upgrade is suspended until the instance is master again. Restarting the upgrade on a new master works only if the old one has been removed from the replica set (_cluster system space).

Usage example

Suppose there are two columns in the space test – id (unsigned) and data (string). The example shows how to upgrade the schema and add another column to the space using space:upgrade(). The new column contains the id values converted to string. Each step takes a while.

The test space is generated with the following script:

local log = require('log')
box.cfg{
    checkpoint_count = 1,
    memtx_memory = 5 * 1024 * 1024 * 1024,
}
box.schema.space.create('test')
box.space.test:format{
    {name = 'id', type = 'unsigned'},
    {name = 'data', type = 'string'},
}
box.space.test:create_index('pk')
local count = 20 * 1000 * 1000
local progress = 0
box.begin()
for i = 1, count do
    box.space.test:insert{i, 'data' .. i}

    if i % 1000 == 0 then
        box.commit()
        local p = math.floor(i / count * 100)
        if progress ~= p then
            progress = p
            log.info('Generating test data set... %d%% done', p)
        end
        box.begin()
    end
end
box.commit()
box.snapshot()
os.exit(0)

To upgrade the space, connect to the server and then run the commands below:

localhost:3301> box.schema.func.create('convert', {
              >     language = 'lua',
              >     is_deterministic = true,
              >     body = [[function(t)
              >         if #t == 2 then
              >             return t:update({{'!', 2, tostring(t.id)}})
              >         else
              >             return t
              >         end
              >     end]],
              > })
localhost:3301> box.space.test:upgrade({
              >     func = 'convert',
              >     format = {
              >         {name = 'id', type = 'unsigned'},
              >         {name = 'id_string', type = 'string'},
              >         {name = 'data', type = 'string'},
              >     },
              > })

While the upgrade is in progress, you can track the state of the upgrade. To check the status, connect to Tarantool from another console and run the following commands:

localhost:3311> box.space.test:upgrade()
---
- status: inprogress
  progress: 8%
  owner: 579a9e99-427e-4e99-9e2e-216bbd3098a7
  func: convert
...

Even though the upgrade is only 8% complete, selecting the data from the space returns the converted tuples:

localhost:3311> box.space.test:select({}, {iterator = 'req', limit = 5})
---
- - [20000000, '20000000', 'data20000000']
  - [19999999, '19999999', 'data19999999']
  - [19999998, '19999998', 'data19999998']
  - [19999997, '19999997', 'data19999997']
  - [19999996, '19999996', 'data19999996']
...

Примечание

The tuples contain the new field even though the space upgrade is still running.

Wait for the space upgrade to complete using the command below:

localhost:3311> box.space.test:upgrade():wait()

Read views

Enterprise Edition

Read views are available in the Enterprise Edition only.

A read view is an in-memory snapshot of the entire database that isn’t affected by future data modifications. Read views provide access to database spaces and their indexes and enable you to retrieve data using the same select and pairs operations.

Read views can be used to make complex analytical queries. This reduces the load on the main database and improves RPS for a single Tarantool instance.

To improve memory consumption and performance, Tarantool creates read views using the copy-on-write technique. In this case, duplication of the entire data set is not required: Tarantool duplicates only blocks modified after a read view is created.

Примечание

Tarantool Enterprise Edition supports read views starting from v2.11.0 and enables the ability to work with them using both Lua and C API.

Limitations

Read views have the following limitations:

Working with read views

Creating a read view

To create a read view, call the box.read_view.open() function. The snippet below shows how to create a read view with the read_view1 name.

tarantool> read_view1 = box.read_view.open({name = 'read_view1'})

After creating a read view, you can see the information about it by calling read_view_object:info().

tarantool> read_view1:info()
---
- timestamp: 66.606817935
  signature: 24
  is_system: false
  status: open
  vclock: {1: 24}
  name: read_view1
  id: 1
...

To list all the created read views, call the box.read_view.list() function.

Querying data

After creating a read view, you can access database spaces using the read_view_object.space field. This field provides access to a space object that exposes the select, get, and pairs methods with the same behavior as corresponding box.space methods.

The example below shows how to select 4 records from the bands space:

tarantool> read_view1.space.bands:select({}, {limit = 4})
---
- - [1, 'Roxette', 1986]
  - [2, 'Scorpions', 1965]
  - [3, 'Ace of Base', 1987]
  - [4, 'The Beatles', 1960]
...

Similarly, you can retrieve data by the specific index.

tarantool> read_view1.space.bands.index.year:select({}, {limit = 4})
---
- - [4, 'The Beatles', 1960]
  - [2, 'Scorpions', 1965]
  - [1, 'Roxette', 1986]
  - [3, 'Ace of Base', 1987]
...

Pagination is supported in read views in the same ways as in select requests to spaces: using the fetch_pos and after arguments. To get the cursor position after executing a request on a read view, set fetch_pos to true:

tarantool> result, position = read_view1.space.bands:select({}, { limit = 3, fetch_pos = true })
---
...

tarantool> result
---
- - [1, 'Roxette', 1986]
  - [2, 'Scorpions', 1965]
  - [3, 'Ace of Base', 1987]
...

tarantool> position
---
- kQM
...

Then, pass this position in the after parameter of a request to get the next data chunk:

tarantool> read_view1.space.bands:select({}, { limit = 3, after = position })
---
- - [4, 'The Beatles', 1960]
  - [5, 'Pink Floyd', 1965]
  - [6, 'The Rolling Stones', 1962]
...

Closing a read view

When a read view is no longer needed, close it using the read_view_object:close() method because a read view may consume a substantial amount of memory.

tarantool> read_view1:close()
---
...

Otherwise, a read view is closed implicitly when the read view object is collected by the Lua garbage collector.

After the read view is closed, its status is set to closed. On an attempt to use it, an error is raised.

Example

A Tarantool session below demonstrates how to open a read view, get data from this view, and close it. To repeat these steps, you need to bootstrap a Tarantool instance as described in Using data operations (you can skip creating secondary indexes).

  1. Insert test data.

    tarantool> bands:insert{1, 'Roxette', 1986}
           bands:insert{2, 'Scorpions', 1965}
           bands:insert{3, 'Ace of Base', 1987}
           bands:insert{4, 'The Beatles', 1960}

  2. Create a read view by calling the open function. Then, make sure that the read view status is open.

    tarantool> read_view1 = box.read_view.open({name = 'read_view1'})

tarantool> read_view1.status
---
- open
...

  3. Change data in a database using the delete and update operations.

    tarantool> bands:delete(4)
---
- [4, 'The Beatles', 1960]
...
tarantool> bands:update({2}, {{'=', 2, 'Pink Floyd'}})
---
- [2, 'Pink Floyd', 1965]
...

  4. Query a read view to make sure it contains a snapshot of data before a database is updated.

    tarantool> read_view1.space.bands:select()
---
- - [1, 'Roxette', 1986]
  - [2, 'Scorpions', 1965]
  - [3, 'Ace of Base', 1987]
  - [4, 'The Beatles', 1960]
...

  5. Close a read view.

    tarantool> read_view1:close()
---
...

SQL guides

This section contains hands-on SQL guides. You might also want to read the in-depth SQL reference.

SQL beginners“ guide

The Beginners“ Guide describes how users can start up with SQL with Tarantool, and necessary concepts.

The SQL Beginners“ Guide is about databases in general, and about the relationship between Tarantool’s NoSQL and SQL products. Most of the matters in the Beginners“ Guide will already be familiar to people who have used relational databases before.

Prerequisites

Before starting this tutorial:

  1. Install the tt CLI utility.

  2. Start a Tarantool instance in the interactive mode by running tt run -i:

    $ tt run -i
Tarantool 3.0.0-0-g6ba34da7f8
type 'help' for interactive help
tarantool>

  3. Initialize the instance and switch the input language to SQL:

    tarantool> box.cfg{}
tarantool> \set language sql
tarantool>  \set delimiter ;

Now you have a running Tarantool instance that accepts SQL input.

Sample table

In football training camp it is traditional for the trainer to begin by showing a football and saying «this is a football». In that spirit, this is a table:

TABLE
          [1]              [2]              [3]
       +-----------------+----------------+----------------+
 Row#1 | Row#1,Column#1  | Row#1,Column#2 | Row#1,Column#3 |
       +-----------------+----------------+----------------+
 Row#2 | Row#2,Column#1  | Row#2,Column#2 | Row#2,Column#3 |
       +-----------------+----------------+----------------+
 Row#3 | Row#3,Column#1  | Row#3,Column#2 | Row#3,Column#3 |
       +-----------------+----------------+----------------+

But the labels are misleading – one usually doesn’t identify rows and columns by their ordinal positions, one prefers to pick out specific items by their contents. In that spirit, this is a table:

MODULES

+-----------------+------+---------------------+
| NAME            | SIZE | PURPOSE             |
+-----------------+------+---------------------+
| box             | 1432 | Database Management |
| clock           |  188 | Seconds             |
| crypto          |    4 | Cryptography        |
+-----------------+------+---------------------+

So one does not use longitude/latitude navigation by talking about «Row#2 Column #2», one uses the contents of the Name column and the name of the Size column by talking about «the size, where the name is „clock“». To be more exact, this is what one says:

SELECT size FROM modules WHERE name = 'clock';

If you’re familiar with Tarantool’s architecture – and ideally you read about that before coming to this chapter – then you know that there is a NoSQL way to get the same thing:

box.space.MODULES:select()[2][2]

Well, you can do that. One of the advantages of Tarantool is that if you can get data via an SQL statement, then you can get the same data via a NoSQL request. But the reverse is not true, because not all NoSQL tuple sets are definable as SQL tables. These restrictions apply for SQL that do not apply for NoSQL:
1. Every column must have a name.
2. Every column should have a scalar type (Tarantool is relaxed about which particular scalar type you can have, but there is no way to index and search arrays, tables within tables, or what MessagePack calls «maps».)

Tarantool/NoSQL’s «format» clause causes the same restrictions.

So an SQL «table» is a NoSQL «tuple set with format restrictions», an SQL «row» is a NoSQL «tuple», an SQL «column» is a NoSQL «list of fields within a tuple set».

Creating a table

This is how to create the modules table:

CREATE TABLE modules (name STRING, size INTEGER, purpose STRING, PRIMARY KEY (name));

The words that are IN CAPITAL LETTERS are «keywords» (although it is only a convention in this manual that keywords are in capital letters, in practice many programmers prefer to avoid shouting). A keyword has meaning for the SQL parser so many keywords are reserved, they cannot be used as names unless they are enclosed inside quotation marks.

The word «modules» is a «table name», and the words «name» and «size» and «purpose» are «column names». All tables and all columns must have names.

The words «STRING» and «INTEGER» are «data types». STRING means «the contents should be characters, the length is indefinite, the equivalent NoSQL type is „string““». INTEGER means «the contents should be numbers without decimal points, the equivalent NoSQL type is „integer“». Tarantool supports other data types but this section’s example table has data types from the two main groups, namely, data types for numbers and data types for strings.

The final clause, PRIMARY KEY (name), means that the name column is the main column used to identify the row.

Nulls

Frequently it is necessary, at least temporarily, that a column value should be NULL. Typical situations are: the value is unknown, or the value is not applicable. For example, you might make a module as a placeholder but you don’t want to say its size or purpose. If such things are possible, the column is «nullable». The example table’s name column cannot contain nulls, and it could be defined explicitly as «name STRING NOT NULL», but in this case that’s unnecessary – a column defined as PRIMARY KEY is automatically NOT NULL.

Is a NULL in SQL the same thing as a nil in Lua? No, but it is close enough that there will be confusion. When nil means «unknown» or «inapplicable», yes. But when nil means «nonexistent» or «type is nil», no. NULL is a value, it has a data type because it is inside a column which is defined with that data type.

Creating an index

This is how to create indexes for the modules table:

CREATE INDEX size ON modules (size);
CREATE UNIQUE INDEX purpose ON modules (purpose);

There is no need to create an index on the name column, because Tarantool creates an index automatically when it sees a PRIMARY KEY clause in the CREATE TABLE statement. In fact there is no need to create indexes on the size or purpose columns either – if indexes don’t exist, then it is still possible to use the columns for searches. Typically people create non-primary indexes, also called secondary indexes, when it becomes clear that the table will grow large and searches will be frequent, because searching with an index is generally much faster than searching without an index.

Another use for indexes is to enforce uniqueness. When an index is created with CREATE UNIQUE INDEX for the purpose column, it is not possible to have duplicate values in that column.

Data change

Putting data into a table is called «inserting». Changing data is called «updating». Removing data is called «deleting». Together, the three SQL statements INSERT plus UPDATE plus DELETE are the three main «data-change» statements.

This is how to insert, update, and delete a row in the modules table:

INSERT INTO modules VALUES ('json', 14, 'format functions for JSON');
UPDATE modules SET size = 15 WHERE name = 'json';
DELETE FROM modules WHERE name = 'json';

The corresponding non-SQL Tarantool requests would be:

box.space.MODULES:insert{'json', 14, 'format functions for JSON'}
box.space.MODULES:update('json', {{'=', 2, 15}})
box.space.MODULES:delete{'json'}

This is how one would populate the table with the values that was shown earlier:

INSERT INTO modules VALUES ('box', 1432, 'Database Management');
INSERT INTO modules VALUES ('clock', 188, 'Seconds');
INSERT INTO modules VALUES ('crypto', 4, 'Cryptography');

Constraints

Some data-change statements are illegal due to something in the table’s definition. This is called «constraining what can be done». Some types of constraints have already been shown …

NOT NULL – if a column is defined with a NOT NULL clause, it is illegal to put NULL into it. A primary-key column is automatically NOT NULL.

UNIQUE – if a column has a UNIQUE index, it is illegal to put a duplicate into it. A primary-key column automatically has a UNIQUE index.

data domain – if a column is defined as having data type INTEGER, it is illegal to put a non-number into it. More generally, if a value doesn’t correspond to the data type of the definition, it is illegal. Some database management systems (DBMSs) are very forgiving and will try to make allowances for bad values rather than reject them; Tarantool is a bit more strict than those DBMSs.

Now, here are other types of constraints …

CHECK – a table description can have a clause «CHECK (conditional expression)». For example, if the CREATE TABLE modules statement looked like this:

CREATE TABLE modules (name STRING,
                      size INTEGER,
                      purpose STRING,
                      PRIMARY KEY (name),
                      CHECK (size > 0));

then this INSERT statement would be illegal:
INSERT INTO modules VALUES ('box', 0, 'The Database Kernel');
because there is a CHECK constraint saying that the second column, the size column, cannot contain a value which is less than or equal to zero. Try this instead:
INSERT INTO modules VALUES ('box', 1, 'The Database Kernel');

FOREIGN KEY – a table description can have a clause «FOREIGN KEY (column-list) REFERENCES table (column-list)». For example, if there is a new table «submodules» which in a way depends on the modules table, it can be defined like this:

CREATE TABLE submodules (name STRING,
                         module_name STRING,
                         size INTEGER,
                         purpose STRING,
                         PRIMARY KEY (name),
                         FOREIGN KEY (module_name) REFERENCES
                         modules (name));

Now try to insert a new row into this submodules table:

INSERT INTO submodules VALUES
  ('space', 'Box', 10000, 'insert etc.');

The insert will fail because the second column (module_name) refers to the name column in the modules table, and the name column in the modules table does not contain „Box“. However, it does contain „box“. By default searches in Tarantool’s SQL use a binary collation. This will work:

INSERT INTO submodules
  VALUES ('space', 'box', 10000, 'insert etc.');

Now try to delete the corresponding row from the modules table:

DELETE FROM modules WHERE name = 'box';

The delete will fail because the second column (module_name) in the submodules table refers to the name column in the modules table, and the name column in the modules table would not contain „box“ if the delete succeeded. So the FOREIGN KEY constraint affects both the table which contains the FOREIGN KEY clause and the table that the FOREIGN KEY clause refers to.

The constraints in a table’s definition – NOT NULL, UNIQUE, data domain, CHECK, and FOREIGN KEY – are guarantors of the database’s integrity. It is important that they are fixed and well-defined parts of the definition, and hard to bypass with SQL. This is often seen as a difference between SQL and NoSQL – SQL emphasizes law and order, NoSQL emphasizes freedom and making your own rules.

Table relationships

Think about the two tables that have been discussed so far:

CREATE TABLE modules (name STRING,
                      size INTEGER,
                       purpose STRING,
                       PRIMARY KEY (name),
                       CHECK (size > 0));

CREATE TABLE submodules (name STRING,
                         module_name STRING,
                         size INTEGER,
                         purpose STRING,
                         PRIMARY KEY (name),
                         FOREIGN KEY (module_name) REFERENCES
                         modules (name));

Because of the FOREIGN KEYS clause in the submodules table, there is clearly a many-to-one relationship:
submodules –>> modules
that is, every submodules row must refer to one (and only one) modules row, while every modules row can be referred to in zero or more submodules rows.

Table relationships are important, but beware: do not trust anyone who tells you that databases made with SQL are relational «because there are relationships between tables». That is wrong, as will be clear in the discussion about what makes a database relational, later.

Selecting with WHERE

Важно

By default, Tarantool prohibits SELECT queries that scan table rows instead of using indexes to avoid unwanted heavy load. For the purposes of this tutorial, allow SQL scan queries in Tarantool by running the command:

SET SESSION "sql_seq_scan" = true;

Alternatively, you can allow a specific query to perform a table scan by adding the SEQSCAN keyword before the table name. Learn more about using SEQSCAN in SQL scan queries in the SQL FROM clause description.

We gave a simple example of a SELECT statement earlier:

SELECT size FROM modules WHERE name = 'clock';

The clause «WHERE name = „clock“» is legal in other statements – it is in examples with UPDATE and DELETE – but here the only examples will be with SELECT.

The first variation is that the WHERE clause does not have to be specified at all, it is optional. So this statement would return all rows:

SELECT size FROM modules;

The second variation is that the comparison operator does not have to be „=“, it can be anything that makes sense: „>“ or „>=“ or „<“ or „<=“, or „LIKE“ which is an operator that works with strings that may contain wildcard characters „_“ meaning „match any one character“ or „%“ meaning „match any zero or one or many characters“. These are legal statements which return all rows:

SELECT size FROM modules WHERE name >= '';
SELECT size FROM modules WHERE name LIKE '%';

The third variation is that IS [NOT] NULL is a special condition. Remembering that the NULL value can mean «it is unknown what the value should be», and supposing that in some row the size is NULL, then the condition «size > 10» is not certainly true and it is not certainly false, so it is evaluated as «unknown». Ordinarily the application of a WHERE clause filters out both false and unknown results. So when searching for NULL, say IS NULL; when searching anything that is not NULL, say IS NOT NULL. This statement will return all rows because (due to the definition) there are no NULLs in the name column:

SELECT size FROM modules WHERE name IS NOT NULL;

The fourth variation is that conditions can be combined with AND / OR, and negated with NOT.

So this statement would return all rows (the first condition is false but the second condition is true, and OR means «return true if either condition is true»):

SELECT size
FROM modules
WHERE name = 'wombat' OR size IS NOT NULL;

Selecting with a select list

Yet again, here is a simple example of a SELECT statement:

SELECT size FROM modules WHERE name = 'clock';

The words between SELECT and FROM are the select list. In this case, the select list is just one word: size. Formally it means that the desire is to return the size values, and technically the name for picking a particular column is called «projection».

The first variation is that one can specify any column in any order:

SELECT name, purpose, size FROM modules;

The second variation is that one can specify an expression, it does not have to be a column name, it does not even have to include a column name. The common expression operators for numbers are the arithmetic operators + - / *; the common expression operator for strings is the concatenation operator ||. For example this statement will return 8, „XY“:

SELECT size * 2, 'X' || 'Y' FROM modules WHERE size = 4;

The third variation is that one can add a clause [AS name] after every expression, so that in the return the column titles will make sense. This is especially important when a title might otherwise be ambiguous or meaningless. For example this statement will return 8, „XY“ as before

SELECT size * 2 AS double_size, 'X' || 'Y' AS concatenated_literals  FROM modules
  WHERE size = 4;

but displayed as a table the result will look like

+----------------+------------------------+
| DOUBLE_SIZE    | CONCATENATED_LITERALS  |
+----------------+------------------------+
|              8 | XY                     |
+----------------+------------------------+

Selecting with a select list with asterisk

Instead of listing columns in a select list, one can just say '*'. For example

SELECT * FROM modules;

This is the same thing as

SELECT name, size, purpose FROM modules;

Selecting with "*" saves time for the writer, but it is unclear to a reader who has not memorized what the column names are. Also it is unstable, because there is a way to change a table’s definition (the ALTER statement, which is an advanced topic). Nevertheless, although it might be bad to use it for production, it is handy to use it for introduction, so "*" will appear in some following examples.

Select with subqueries

Remember that there is a modules table and there is a submodules table. Suppose that there is a desire to list the submodules that refer to modules for which the purpose is X. That is, this involves a search of one table using a value in another table. This can be done by enclosing «(SELECT …)» within the WHERE clause. For example:

SELECT name FROM submodules
WHERE module_name =
    (SELECT name FROM modules WHERE purpose LIKE '%Database%');

Subqueries are also useful in the select list, when one wishes to combine information from more than one table. For example this statement will display submodules rows but will include values that come from the modules table:

SELECT name AS submodules_name,
    (SELECT purpose FROM modules
     WHERE modules.name = submodules.module_name)
     AS modules_purpose,
    purpose AS submodules_purpose
FROM submodules;

Whoa. What are «modules.name» and «submodules.name»? Whenever you see «x . y» you are looking at a «qualified column name», and the first part is a table identifier, the second part is a column identifier. It is always legal to use qualified column names, but until now it has not been necessary. Now it is necessary, or at least it is a good idea, because both tables have a column named «name».

The result will look like this:

+-------------------+------------------------+--------------------+
| SUBMODULES_NAME   | MODULES_PURPOSE        | SUBMODULES_PURPOSE |
+-------------------+------------------------+--------------------+
| space             | Database Management    | insert etc.        |
+-------------------+------------------------+--------------------+

Perhaps you have read somewhere that SQL stands for «Structured Query Language». That is not true any more. But it is true that the query syntax allows for a structural component, namely the subquery, and that was the original idea. However, there is a different way to combine tables – with joins instead of subqueries.

Select with Cartesian join

Until now only «FROM modules» or «FROM submodules» was used in SELECT statements. What if there was more than one table in the FROM clause? For example

SELECT * FROM modules, submodules;

or

SELECT * FROM modules JOIN submodules;

That is legal. Usually it is not what you want, but it is a learning aid. The result will be:

{ columns from modules table }         { columns from submodules table }
+--------+------+---------------------+-------+-------------+-------+-------------+
| NAME   | SIZE | PURPOSE             | NAME  | MODULE_NAME | SIZE  | PURPOSE     |
+--------+------+---------------------+-------+-------------+-------+-------------+
| box    | 1432 | Database Management | space | box         | 10000 | insert etc. |
| clock  |  188 | Seconds             | space | box         | 10000 | insert etc. |
| crypto |    4 | Cryptography        | space | box         | 10000 | insert etc. |
+--------+------+---------------------+-------+-------------+-------+-------------+

It is not an error. The meaning of this type of join is «combine every row in table-1 with every row in table-2». It did not specify what the relationship should be, so the result has everything, even when the submodule has nothing to do with the module.

It is handy to look at the above result, called a «Cartesian join» result, to see what would really be desirable. Probably for this case the row that actually makes sense is the one where the modules.name = submodules.module_name, and it’s better to make that clear in both the select list and the WHERE clause, thus:

SELECT modules.name AS modules_name,
       modules.size AS modules_size,
       modules.purpose AS modules_purpose,
       submodules.name,
       module_name,
       submodules.size,
       submodules.purpose
FROM modules, submodules
WHERE modules.name = submodules.module_name;

The result will be:

+----------+-----------+------------+--------+---------+-------+-------------+
| MODULES_ |  MODULES_ | MODULES_   | NAME   | MODULE_ | SIZE  | PURPOSE     |
| NAME     |  SIZE     | PURPOSE    |        | NAME    |       |             |
+----------+-----------+--------- --+--------+---------+-------+-------------+
| box      |      1432 | Database   | space  | box     | 10000 | insert etc. |
|          |           | Management |        |         |       |             |
+----------+-----------+------------+--------+---------+-------+-------------+

In other words, you can specify a Cartesian join in the FROM clause, then you can filter out the irrelevant rows in the WHERE clause, and then you can rename columns in the select list. This is fine, and every SQL DBMS supports this. But it is worrisome that the number of rows in a Cartesian join is always (number of rows in first table multiplied by number of rows in second table), which means that conceptually you are often filtering in a large set of rows.

It is good to start by looking at Cartesian joins because they show the concept. Many people, though, prefer to use different syntaxes for joins because they look better or clearer. So now those alternatives will be shown.

Select with join with ON clause

The ON clause would have the same comparisons as the WHERE clause that was illustrated for the previous section, but the use of different syntax would be making it clear «this is for the sake of the join». Readers can see at a glance that it is, in concept at least, an initial step before the result rows are filtered. For example this

SELECT * FROM modules JOIN submodules
  ON (modules.name = submodules.module_name);

is the same as

SELECT * FROM modules, submodules
  WHERE modules.name = submodules.module_name;

Select with join with USING clause

The USING clause would take advantage of names that are held in common between the two tables, with the assumption that the intent is to match those columns with „=“ comparisons. For example,

SELECT * FROM modules JOIN submodules USING (name);

has the same effect as

SELECT * FROM modules JOIN submodules WHERE modules.name = submodules.name;

If the table had been created with a plan in advance to use USING clauses, that would save time. But that did not happen. So, although the above example «works», the results will not be sensible.

Select with natural join

A natural join would take advantage of names that are held in common between the two tables, and would do the filtering automatically based on that knowledge, and throw away duplicate columns.

If the table had been created with a plan in advance to use natural joins, that would be very handy. But that did not happen. So, although the following example «works», the results won’t be sensible.

SELECT * FROM modules NATURAL JOIN submodules;

Result: nothing, because modules.name does not match submodules.name, and so on And even if there had been a result, it would only have included four columns: name, module_name, size, purpose.

Select with left join

Now what if there is a desire to join modules to submodules, but it’s necessary to be sure that all the modules are found? In other words, suppose the requirement is to get modules even if the condition submodules.module_name = modules.name is not true, because the module has no submodules.

When that is the requirement, the type of join is an «outer join» (as opposed to the type that has been used so far which is an «inner join»). Specifically the format will be LEFT [OUTER] JOIN because the main table, modules, is on the left. For example:

SELECT *
FROM modules LEFT JOIN submodules
ON modules.name = submodules.module_name;

which returns:

{ columns from modules table }         { columns from submodules table }
+--------+------+---------------------+-------+-------------+-------+-------------+
| NAME   | SIZE | PURPOSE             | NAME  | MODULE_NAME | SIZE  | PURPOSE     |
+--------+------+---------------------+-------+-------------+-------+-------------+
| box    | 1432 | Database Management | space | box         | 10000 | insert etc. |
| clock  |  188 | Seconds             | NULL  | NULL        | NULL  | NULL        |
| crypto |    4 | Cryptography        | NULL  | NULL        | NULL  | NULL        |
+--------+------+---------------------+-------+-------------+-------+-------------+

Thus, for the submodules of the clock module and the submodules of the crypto module – which do not exist – there are NULLs in every column.

Select with functions

A function can take any expression, including an expression that contains another function, and return a scalar value. There are many such functions. Here will be a description of only one, SUBSTR, which returns a substring of a string.

Format: SUBSTR(input-string, start-with [, length])

Description: SUBSTR takes input-string, eliminates any characters before start-with, eliminates any characters after (start-with plus length), and returns the result.

Example: SUBSTR('abcdef', 2, 3) returns „bcd“.

Select with aggregation, GROUP BY, and HAVING

Remember that the modules table looks like this:

MODULES

+-----------------+------+---------------------+
| NAME            | SIZE | PURPOSE             |
+-----------------+------+---------------------+
| box             | 1432 | Database Management |
| clock           |  188 | Seconds             |
| crypto          |    4 | Cryptography        |
+-----------------+------+---------------------+

Suppose that there is no need to know all the individual size values, all that is important is their aggregation, that is, take the attributes of the collection. SQL allows aggregation functions including: AVG (average), SUM, MIN (minimum), MAX (maximum), and COUNT. For example

SELECT AVG(size), SUM(size), MIN(size), MAX(size), COUNT(size) FROM modules;

The result will look like this:

+-----------+-----------+-----------+-----------+-----------+
| COLUMN_1  | COLUMN_2  | COLUMN_3  | COLUMN_4  | COLUMN_5  |
+-----------+-----------+-----------+-----------+-----------|
|       541 |      1624 |         4 |      1432 |         3 |
+-----------+-----------+-----------+-----------+-----------+

Suppose that the requirement is aggregations, but aggregations of rows that have some common characteristic. Supposing further, the rows should be divided into two groups, the ones whose names begin with „b“ and the ones whose names begin with „c“. This can be done by adding a clause [GROUP BY expression]. For example,

SELECT SUBSTR(name, 1, 1), AVG(size), SUM(size), MIN(size), MAX(size), COUNT(size)
FROM modules
GROUP BY SUBSTR(name, 1, 1);

The result will look like this:

+------------+--------------+-----------+-----------+-----------+-------------+
| COLUMN_1   | COLUMN_2     | COLUMN_3  | COLUMN_4  | COLUMN_5  | COLUMN_6    |
+------------+--------------+-----------+-----------+-----------+-------------+
| b          |         1432 |      1432 |      1432 |      1432 |           1 |
| c          |           96 |       192 |         4 |       188 |           2 |
+------------+--------------+-----------+-----------+-----------+-------------+

Select with common table expression

It is possible to define a temporary (viewed) table within a statement, usually within a SELECT statement, using a WITH clause. For example:

WITH tmp_table AS (SELECT x1 FROM t1) SELECT * FROM tmp_table;

Select with order, limit, and offset clauses

So far, tor every search in the modules table, the rows have come out in alphabetical order by name: „box“, then „clock“, then „crypto“. However, to really be sure about the order, or to ask for a different order, it is necessary to be explicit and add a clause: ORDER BY column-name [ASC|DESC]. (ASC stands for ASCending, DESC stands for DESCending.) For example:

SELECT * FROM modules ORDER BY name DESC;

The result will be the usual rows, in descending alphabetical order: „crypto“ then „clock“ then „box“.

After the ORDER BY clause there can be a clause LIMIT n, where n is the maximum number of rows to retrieve. For example:

SELECT * FROM modules ORDER BY name DESC LIMIT 2;

The result will be the first two rows, „crypto“ and „clock“.

After the ORDER BY clause and the LIMIT clause there can be a clause OFFSET n, where n is the row to start with. The first offset is 0. For example:

SELECT * FROM modules ORDER BY name DESC LIMIT 2 OFFSET 2;

The result will be the third row, „box“.

Views

A view is a canned SELECT. If you have a complex SELECT that you want to run frequently, create a view and then do a simple SELECT on the view. For example:

CREATE VIEW v AS SELECT size, (size *5) AS size_times_5
FROM modules
GROUP BY size, name
ORDER BY size_times_5;
SELECT * FROM v;

Transactions

Tarantool has a «Write Ahead Log» (WAL). Effects of data-change statements are logged before they are permanently stored on disk. This is a reason that, although entire databases can be stored in temporary memory, they are not vulnerable in case of power failure.

Tarantool supports commits and rollbacks. In effect, asking for a commit means asking for all the recent data-change statements, since a transaction began, to become permanent. In effect, asking for a rollback means asking for all the recent data-change statements, since a transaction began, to be cancelled.

For example, consider these statements:

CREATE TABLE things (remark STRING, PRIMARY KEY (remark));
START TRANSACTION;
INSERT INTO things VALUES ('A');
COMMIT;
START TRANSACTION;
INSERT INTO things VALUES ('B');
ROLLBACK;
SELECT * FROM things;

The result will be: one row, containing „A“. The ROLLBACK cancelled the second INSERT statement, but did not cancel the first one, because it had already been committed.

Ordinarily every statement is automatically committed.

After START TRANSACTION, statements are not automatically committed – Tarantool considers that a transaction is now «active», until the transaction ends with a COMMIT statement or a ROLLBACK statement. While a transaction is active, all statements are legal except another START TRANSACTION.

Implementing Tarantool’s SQL On Top of NoSQL

Tarantool’s SQL data is the same as Tarantool’s NoSQL data. When you create a table or an index with SQL, you are creating a space or an index in NoSQL. For example:

CREATE TABLE things (remark STRING, PRIMARY KEY (remark));
INSERT INTO things VALUES ('X');

is somewhat similar to

box.schema.space.create('THINGS',
{
    format = {
              [1] = {["name"] = "REMARK", ["type"] = "string"}
              }
})
box.space.THINGS:create_index('pk_unnamed_THINGS_1',{unique=true,parts={1,'string'}})
box.space.THINGS:insert{'X'}

Therefore you can take advantage of Tarantool’s NoSQL features even though your primary language is SQL. Here are some possibilities.

(1) NoSQL applications written in one of the connector languages may be slightly faster than SQL applications because SQL statements may require more parsing and may be translated to NoSQL requests.

(2) You can write stored procedures in Lua, combining Lua loop-control and Lua library-access statements with SQL statements. These routines are executed on the server, which is the principal advantage of pure-SQL stored procedures.

(3) There are some options that are implemented in NoSQL that are not (yet) implemented in SQL. For example you can use NoSQL to change an index option, and to deny access to users named „guest“.

(4) System spaces such as _space and _index can be accessed with SQL SELECT statements. This is not quite the same as an information_schema, but it does mean that you can use SQL to access the database’s metadata catalog.

Fields in NoSQL spaces can be accessed with SQL if and only if they are scalar and are defined in format clauses. Indexes of NoSQL spaces will be used with SQL if and only if they are TREE indexes.

Relational databases

Edgar F. Codd, the person most responsible for researching and explaining relational database concepts, listed the main criteria as (Codd’s 12 rules).

Although Tarantool is not advertised as «relational», Tarantool comes with a claim that it complies with these rules, with the following caveats and exceptions …

The rules state that all data must be viewable as relations. A Tarantool SQL table is a relation. However, it is possible to have duplicate values in SQL tables and it is possible to have an implicit ordering. Those characteristics are not allowed for true relations.

The rules state that there must be a dynamic online catalog. Tarantool has one but some metadata is missing from it.

The rules state that the data language must support authorization. Tarantool’s SQL does not. Authorization occurs via NoSQL requests.

The rules require that data must be physically independent (from underlying storage changes) and logically independent (from application program changes). So far there is not enough experience to make this guarantee.

The rules require certain types of updatable views. Tarantool’s views are not updatable.

The rules state that it should be impossible to use a low-level language to bypass integrity as defined in the relational-level language. In Tarantool’s case, this is not true, for example one can execute a request with Tarantool’s NoSQL to violate a foreign-key constraint that was defined with Tarantool’s SQL.

To learn more about SQL in Tarantool, check the reference.

SQL tutorial

This tutorial is a demonstration of the support for SQL in Tarantool. It includes the functionality that you’d encounter in an «SQL-101» course.

Prerequisites

Before starting this tutorial:

  1. Install the tt CLI utility.

  2. Start a Tarantool instance in the interactive mode by running tt run -i:

    $ tt run -i
Tarantool 3.0.0-0-g6ba34da7f8
type 'help' for interactive help
tarantool>

  3. Initialize the instance and switch the input language to SQL:

    tarantool> box.cfg{}
tarantool> \set language sql
tarantool>  \set delimiter ;

Now you have a running Tarantool instance that accepts SQL input.

Create a table and execute SQL statements

CREATE, INSERT, UPDATE, SELECT

To get started, enter these SQL statements:

CREATE TABLE table1 (column1 INTEGER PRIMARY KEY, column2 VARCHAR(100));
INSERT INTO table1 VALUES (1, 'A');
UPDATE table1 SET column2 = 'B';
SELECT * FROM table1 WHERE column1 = 1;

The result of the SELECT statement looks like this:

sql_tutorial:instance001> SELECT * FROM table1 WHERE column1 = 1;
---
- metadata:
  - name: COLUMN1
    type: integer
  - name: COLUMN2
    type: string
  rows:
  - [1, 'B']
...

The result includes:

  • metadata: the names and data types of each column
  • result rows

For conciseness, metadata is skipped in query results in this tutorial. Only the result rows are shown.

CREATE TABLE

Here is CREATE TABLE with more details:

  • There are multiple columns, with different data types.
  • There is a PRIMARY KEY (unique and not-null) for two of the columns.

Create another table:

CREATE TABLE table2 (column1 INTEGER,
                     column2 VARCHAR(100),
                     column3 SCALAR,
                     column4 DOUBLE,
                     PRIMARY KEY (column1, column2));

The result is: row_count: 1.

INSERT

Put four rows in the table (table2):

  • The INTEGER and DOUBLE columns get numbers
  • The VARCHAR and SCALAR columns get strings (the SCALAR strings are expressed as hexadecimals)
INSERT INTO table2 VALUES (1, 'AB', X'4142', 5.5);
INSERT INTO table2 VALUES (1, 'CD', X'2020', 1E4);
INSERT INTO table2 VALUES (2, 'AB', X'2020', 12.34567);
INSERT INTO table2 VALUES (-1000, '', X'', 0.0);

Then try to put another row:

INSERT INTO table2 VALUES (1, 'AB', X'A5', -5.5);

This INSERT fails because of a primary-key violation: the row with the primary key 1, 'AB' already exists.

The SEQSCAN keyword

Sequential scan is the scan through all the table rows instead of using indexes. In Tarantool, SELECT SQL queries that perform sequential scans are prohibited by default. For example, this query leads to the error Scanning is not allowed for 'table2':

SELECT * FROM table2;

To execute a scan query, put the SEQSCAN keyword before the table name:

SELECT * FROM SEQSCAN table2;

Try to execute these queries that use indexed column1 in filters:

SELECT * FROM table2 WHERE column1 = 1;
SELECT * FROM table2 WHERE column1 + 1 = 2;

The result is:

  • The first query returns rows:

    - [1, 'AB', 'AB', 10.5]
- [1, 'CD', '  ', 10005]

  • The second query fails with the error Scanning is not allowed for 'TABLE2'. Although column1 is indexed, the expression column1 + 1 is not calculated from the index, which makes this SELECT a scan query.

Примечание

To enable SQL scan queries without SEQSCAN for the current session, run this command:

SET SESSION "sql_seq_scan" = true;

Learn more about using SEQSCAN in the SQL FROM clause description.

SELECT with ORDER BY clause

Retrieve the 4 rows in the table, in descending order by column2, then (where the column2 values are the same) in ascending order by column4.

* is short for «all columns».

SELECT * FROM SEQSCAN table2 ORDER BY column2 DESC, column4 ASC;

The result is:

- - [1, 'CD', '  ', 10000]
  - [1, 'AB', 'AB', 5.5]
  - [2, 'AB', '  ', 12.34567]
  - [-1000, '', '', 0]

SELECT with WHERE clauses

Retrieve some of what you inserted:

  • The first statement uses the LIKE comparison operator which is asking for «first character must be „A“, the next characters can be anything.»
  • The second statement uses logical operators and parentheses, so the AND expressions must be true, or the OR expression must be true. Notice the columns don’t have to be indexed.
SELECT column1, column2, column1 * column4 FROM SEQSCAN table2 WHERE column2
LIKE 'A%';
SELECT column1, column2, column3, column4 FROM SEQSCAN table2
    WHERE (column1 < 2 AND column4 < 10)
    OR column3 = X'2020';

The first result is:

- - [1, 'AB', 5.5]
  - [2, 'AB', 24.69134]

The second result is:

- - [-1000, '', '', 0]
  - [1, 'AB', 'AB', 5.5]
  - [1, 'CD', '  ', 10000]
  - [2, 'AB', '  ', 12.34567]

SELECT with GROUP BY and aggregate functions

Retrieve with grouping.

The rows that have the same values for column2 are grouped and are aggregated – summed, counted, averaged – for column4.

SELECT column2, SUM(column4), COUNT(column4), AVG(column4)
FROM SEQSCAN table2
GROUP BY column2;

The result is:

- - ['', 0, 1, 0]
  - ['AB', 17.84567, 2, 8.922835]
  - ['CD', 10000, 1, 10000]

Complications and complex SELECTs

NULLs

Insert rows that contain NULL values.

NULL is not the same as Lua nil; it commonly is used in SQL for unknown or not-applicable.

INSERT INTO table2 VALUES (1, NULL, X'4142', 5.5);
INSERT INTO table2 VALUES (0, '!!@', NULL, NULL);
INSERT INTO table2 VALUES (0, '!!!', X'00', NULL);

The results are:

  • The first INSERT fails because NULL is not permitted for a column that was defined with a PRIMARY KEY clause.
  • The other INSERT statements succeed.

Indexes

Create a new index on column4.

There already is an index for the primary key. Indexes are useful for making queries faster. In this case, the index also acts as a constraint, because it prevents two rows from having the same values in column4. However, it is not an error that column4 has multiple occurrences of NULLs.

CREATE UNIQUE INDEX i ON table2 (column4);

The result is: rowcount: 1.

Create a subset table

Create a table table3, which contains a subset of the table2 columns and a subset of the table2 rows.

You can do this by combining INSERT with SELECT. Then select everything from the result table.

CREATE TABLE table3 (column1 INTEGER, column2 VARCHAR(100), PRIMARY KEY
(column2));
INSERT INTO table3 SELECT column1, column2 FROM SEQSCAN table2 WHERE column1 <> 2;
SELECT * FROM SEQSCAN table3;

The result is:

- - [-1000, '']
  - [0, '!!!']
  - [0, '!!@']
  - [1, 'AB']
  - [1, 'CD']

SELECT with a subquery

A subquery is a query within a query.

Find all the rows in table2 whose (column1, column2) values are not present in table3.

SELECT * FROM SEQSCAN table2 WHERE (column1, column2) NOT IN (SELECT column1,
column2 FROM SEQSCAN table3);

The result is the single row that was excluded when inserting the rows with the INSERT ... SELECT statement:

- - [2, 'AB', '  ', 12.34567]

SELECT with a join

A join is a combination of two tables. There is more than one way to do them in Tarantool, for example, «Cartesian joins» or «left outer joins».

This example shows the most typical case, where column values from one table match column values from another table.

SELECT * FROM SEQSCAN table2, table3
    WHERE table2.column1 = table3.column1 AND table2.column2 = table3.column2
    ORDER BY table2.column4;

The result is:

- - [0, '!!!', "\0", null, 0, '!!!']
  - [0, '!!@', null, null, 0, '!!@']
  - [-1000, '', '', 0, -1000, '']
  - [1, 'AB', 'AB', 5.5, 1, 'AB']
  - [1, 'CD', ' ', 10000, 1, 'CD']

Constraints and foreign keys

CREATE TABLE with a CHECK clause

Create a table that includes a constraint – there must not be any rows containing 13 in column2. After that, try to insert the following row:

CREATE TABLE table4 (column1 INTEGER PRIMARY KEY, column2 INTEGER, CHECK
(column2 <> 13));
INSERT INTO table4 VALUES (12, 13);

Result: the insert fails, as it should, with the message Check constraint 'ck_unnamed_TABLE4_1' failed for tuple.

CREATE TABLE with a FOREIGN KEY clause

Create a table that includes a constraint: there must not be any rows containing values that do not appear in table2.

CREATE TABLE table5 (column1 INTEGER, column2 VARCHAR(100),
    PRIMARY KEY (column1),
    FOREIGN KEY (column1, column2) REFERENCES table2 (column1, column2));
INSERT INTO table5 VALUES (2,'AB');
INSERT INTO table5 VALUES (3,'AB');

Result:

  • The first INSERT statement succeeds because table3 contains a row with [2, 'AB', ' ', 12.34567].
  • The second INSERT statement, correctly, fails with the message Foreign key constraint ''fk_unnamed_TABLE5_1'' failed: foreign tuple was not found.

UPDATE

Due to earlier INSERT statements, these values are in column4 of table2: {0, NULL, NULL, 5.5, 10000, 12.34567}. Add 5 to each of these values except 0. Adding 5 to NULL results in NULL, as SQL arithmetic requires. Use SELECT to see what happened to column4.

UPDATE table2 SET column4 = column4 + 5 WHERE column4 <> 0;
SELECT column4 FROM SEQSCAN table2 ORDER BY column4;

The result is: {NULL, NULL, 0, 10.5, 17.34567, 10005}.

DELETE

Due to earlier INSERT statements, there are 6 rows in table2:

- - [-1000, '', '', 0]
  - [0, '!!!', "\0", null]
  - [0, '!!@', null, null]
  - [1, 'AB', 'AB', 10.5]
  - [1, 'CD', '  ', 10005]
  - [2, 'AB', '  ', 17.34567]

Try to delete the last and first of these rows:

DELETE FROM table2 WHERE column1 = 2;
DELETE FROM table2 WHERE column1 = -1000;
SELECT COUNT(column1) FROM SEQSCAN table2;

The result is:

  • The first DELETE statement causes an error because there’s a foreign-key constraint.
  • The second DELETE statement succeeds.
  • The SELECT statement shows that there are 5 rows remaining.

ALTER TABLE with a FOREIGN KEY clause

Create another constraint that there must not be any rows in table1 containing values that do not appear in table5. This was impossible during the table1 creation because at that time table5 did not exist. You can add constraints to existing tables with the ALTER TABLE statement.

ALTER TABLE table1 ADD CONSTRAINT c
    FOREIGN KEY (column1) REFERENCES table5 (column1);
DELETE FROM table1;
ALTER TABLE table1 ADD CONSTRAINT c
    FOREIGN KEY (column1) REFERENCES table5 (column1);

Result: the ALTER TABLE statement fails the first time because there is a row in table1, and ADD CONSTRAINT requires that the table be empty. After the row is deleted, the ALTER TABLE statement completes successfully. Now there is a chain of references, from table1 to table5 and from table5 to table2.

Triggers

The idea of a trigger is: if a change (INSERT or UPDATE or DELETE) happens, then a further action – perhaps another INSERT or UPDATE or DELETE – will happen.

Set up the following trigger: when a update to table3 is done, do an update to table2. Specify this as FOR EACH ROW, so that the trigger activates 5 times (since there are 5 rows in table3).

SELECT column4 FROM table2 WHERE column1 = 2;
CREATE TRIGGER tr AFTER UPDATE ON table3 FOR EACH ROW
BEGIN UPDATE table2 SET column4 = column4 + 1 WHERE column1 = 2; END;
UPDATE table3 SET column2 = column2;
SELECT column4 FROM table2 WHERE column1 = 2;

Result:

  • The first SELECT shows that the original value of column4 in table2 where column1 = 2 was: 17.34567.
  • The second SELECT returns:
- - [22.34567]

Operators and functions

String operations

You can manipulate string data (usually defined with CHAR or VARCHAR data types) in many ways. For example:

  • concatenate strings with the || operator
  • extract substrings with the SUBSTR function
SELECT column2, column2 || column2, SUBSTR(column2, 2, 1) FROM SEQSCAN table2;

The result is:

- - ['!!!', '!!!!!!', '!']
  - ['!!@', '!!@!!@', '!']
  - ['AB', 'ABAB', 'B']
  - ['CD', 'CDCD', 'D']
  - ['AB', 'ABAB', 'B']

Number operations

You can also manipulate number data (usually defined with INTEGER or DOUBLE data types) in many ways. For example:

  • shift left with the << operator
  • get modulo with the % operator
SELECT column1, column1 << 1, column1 << 2, column1 % 2 FROM SEQSCAN table2;

The result is:

- - [0, 0, 0, 0]
  - [0, 0, 0, 0]
  - [1, 2, 4, 1]
  - [1, 2, 4, 1]
  - [2, 4, 8, 0]

Ranges and limits

Tarantool can handle:

  • integers anywhere in the 4-byte integer range
  • approximate-numerics anywhere in the 8-byte IEEE floating point range
  • any Unicode characters, with UTF-8 encoding and a choice of collations

Insert such values in a new table and see what happens when you select them with arithmetic on a number column and ordering by a string column.

CREATE TABLE t6 (column1 INTEGER, column2 VARCHAR(10), column4 DOUBLE,
PRIMARY KEY (column1));
INSERT INTO t6 VALUES (-1234567890, 'АБВГД', 123456.123456);
INSERT INTO t6 VALUES (+1234567890, 'GD', 1e30);
INSERT INTO t6 VALUES (10, 'FADEW?', 0.000001);
INSERT INTO t6 VALUES (5, 'ABCDEFG', NULL);
SELECT column1 + 1, column2, column4 * 2 FROM SEQSCAN t6 ORDER BY column2;

The result is:

- - [6, 'ABCDEFG', null]
  - [11, 'FADEW?', 2e-06]
  - [1234567891, 'GD', 2e+30]
  - [-1234567889, 'АБВГД', 246912.246912]

Views

A view (or viewed table), is virtual, meaning that its rows aren’t physically in the database, their values are calculated from other tables.

Create a view v3 based on table3 and select from it:

CREATE VIEW v3 AS SELECT SUBSTR(column2,1,2), column4 FROM SEQSCAN t6
WHERE column4 >= 0;
SELECT * FROM v3;

The result is:

- - ['АБ', 123456.123456]
  - ['FA', 1e-06]
  - ['GD', 1e+30]

Common table expressions

By putting WITH + SELECT in front of a SELECT, you can make a temporary view that lasts for the duration of the statement.

Create such a view and select from it:

WITH cte AS (
             SELECT SUBSTR(column2,1,2), column4 FROM SEQSCAN t6
             WHERE column4 >= 0)
SELECT * FROM cte;

The result is the same as the CREATE VIEW result:

- - ['АБ', 123456.123456]
  - ['FA', 1e-06]
  - ['GD', 1e+30]

VALUES

Tarantool can handle statements like SELECT 55; (select without FROM) like some other popular DBMSs. But it also handles the more standard statement VALUES (expression [, expression ...]);.

SELECT 55 * 55, 'The rain in Spain';
VALUES (55 * 55, 'The rain in Spain');

The result of both these statements is:

- - [3025, 'The rain in Spain']

Metadata

To find out the internal structure of the Tarantool database with SQL, select from the Tarantool system tables _space, _index, and _trigger:

SELECT * FROM SEQSCAN "_space";
SELECT * FROM SEQSCAN "_index";
SELECT * FROM SEQSCAN "_trigger";

Actually, these statements select from NoSQL «system spaces».

Select from _space by a table name:

SELECT "id", "name", "owner", "engine" FROM "_space" WHERE "name"='TABLE3';

The result is:

- - [517, 'TABLE3', 1, 'memtx']

Using SQL from Lua

You can execute SQL statements directly from the Lua code without switching to the SQL input.

Change the settings so that the console accepts statements written in Lua instead of statements written in SQL:

sql_tutorial:instance001> \set language lua

box.execute()

You can invoke SQL statements using the Lua function box.execute(string).

sql_tutorial:instance001> box.execute([[SELECT * FROM SEQSCAN table3;]]);

The result is:

- - [-1000, '']
  - [0, '!!!']
  - [0, '!!@']
  - [1, 'AB']
  - [1, 'CD']
...

Create a million-row table

To see how the SQL in Tarantool scales, create a bigger table.

The following Lua code generates one million rows with random data and inserts them into a table. Copy this code into the Tarantool console and wait a bit:

box.execute("CREATE TABLE tester (s1 INT PRIMARY KEY, s2 VARCHAR(10))");

function string_function()
    local random_number
    local random_string
    random_string = ""
    for x = 1, 10, 1 do
        random_number = math.random(65, 90)
        random_string = random_string .. string.char(random_number)
    end
    return random_string
end;

function main_function()
    local string_value, t, sql_statement
    for i = 1, 1000000, 1 do
        string_value = string_function()
        sql_statement = "INSERT INTO tester VALUES (" .. i .. ",'" .. string_value .. "')"
        box.execute(sql_statement)
    end
end;
start_time = os.clock();
main_function();
end_time = os.clock();
print('insert done in ' .. end_time - start_time .. ' seconds');

The result is: you now have a table with a million rows, with a message saying insert done in 88.570578 seconds.

Select from a million-row table

Check how SELECT works on the million-row table:

  • the first query goes by an index because s1 is the primary key
  • the second query does not go by an index
box.execute([[SELECT * FROM tester WHERE s1 = 73446;]]);
box.execute([[SELECT * FROM SEQSCAN tester WHERE s2 LIKE 'QFML%';]]);

The result is:

  • the first statement completes instantaneously
  • the second statement completed noticeably slower

Cleanup and exit

To cleanup all the objects created in this tutorial, switch to the SQL input language again. Then run the DROP statements for all created tables, views, and triggers.

These statements must be entered separately.

sql_tutorial:instance001> \set language sql
sql_tutorial:instance001> DROP TABLE tester;
sql_tutorial:instance001> DROP TABLE table1;
sql_tutorial:instance001> DROP VIEW v3;
sql_tutorial:instance001> DROP TRIGGER tr;
sql_tutorial:instance001> DROP TABLE table5;
sql_tutorial:instance001> DROP TABLE table4;
sql_tutorial:instance001> DROP TABLE table3;
sql_tutorial:instance001> DROP TABLE table2;
sql_tutorial:instance001> DROP TABLE t6;
sql_tutorial:instance001> \set language lua
sql_tutorial:instance001> os.exit();

Improving MySQL with Tarantool

Replicating MySQL is one of the Tarantool’s killer functions. It allows you to keep your existing MySQL database while at the same time accelerating it and scaling it out horizontally. Even if you aren’t interested in extensive expansion, replacing existing replicas with Tarantool can save you money, because Tarantool is more efficient per core than MySQL. To read a testimonial of a company that implemented Tarantool replication on a large scale, see the following article.

If you run into any trouble with regards to the basics of Tarantool, see the Getting started guide or the Data model description. A helpful log for troubleshooting during this tutorial is replicatord.log in /var/log. You can also have a look at the instance’s log example.log in /var/log/tarantool.

The tutorial is intended for CentOS 7.5 and MySQL 5.7. The tutorial requires that systemd and MySQL are installed.

Setting up MySQL

In this section, you configure MySQL and create a database.

  1. First, install the necessary packages in CentOS:

    $ yum -y install git ncurses-devel cmake gcc-c++ boost boost-devel wget unzip nano bzip2 mysql-devel mysql-lib

  2. Clone the Tarantool-MySQL replication package from GitHub:

    $ git clone https://github.com/tarantool/mysql-tarantool-replication.git

  3. Build the replicator with cmake:

    $ cd mysql-tarantool-replication
$ git submodule update --init --recursive
$ cmake .
$ make

  4. The replicator will run as a systemd daemon called replicatord, so, edit its systemd service file (replicatord.service) in the mysql-tarantool-replication repository:

    $ nano replicatord.service

    The following line should be changed:

    ExecStart=/usr/local/sbin/replicatord -c /usr/local/etc/replicatord.cfg

    To change it, replace the .cfg extension with .yml:

    ExecStart=/usr/local/sbin/replicatord -c /usr/local/etc/replicatord.yml

  5. Next, copy the files from the replicatord repository to other necessary locations:

    $ cp replicatord /usr/local/sbin/replicatord
$ cp replicatord.service /etc/systemd/system

  6. Enter MySQL console and create a sample database (depending on your existing installation, you may be a user other than root):

    mysql -u root -p
CREATE DATABASE menagerie;
QUIT

  7. Get some sample data from MySQL. The data will be pulled into the root directory. After that, install it from the terminal.

    cd
wget http://downloads.mysql.com/docs/menagerie-db.zip
unzip menagerie-db.zip
cd menagerie-db
mysql -u root -p menagerie < cr_pet_tbl.sql
mysql -u root -p menagerie < load_pet_tbl.sql
mysql menagerie -u root -p < ins_puff_rec.sql
mysql menagerie -u root -p < cr_event_tbl.sql

  8. Enter MySQL console and massage the data for use with the Tarantool replicator. In this step, you:

    • add an ID
    • change a field name to avoid conflict
    • cut down the number of fields

    With real data, this is the step that involves the most tweaking.

    mysql -u root -p
USE menagerie;
ALTER TABLE pet ADD id INT PRIMARY KEY AUTO_INCREMENT FIRST;
ALTER TABLE pet CHANGE COLUMN 'name' 'name2' VARCHAR(255);
ALTER TABLE pet DROP sex, DROP birth, DROP death;
QUIT

  9. The sample data is set up. Edit MySQL configuration file to use it with the replicator:

    $ cd
$ nano /etc/my.cnf

    Note that your my.cnf for MySQL could be in a slightly different location. Set:

    [mysqld]
binlog_format = ROW
server_id = 1
log-bin = mysql-bin
interactive_timeout = 3600
wait_timeout = 3600
max_allowed_packet = 32M
socket = /var/lib/mysql/mysql.sock
bind-address = 127.0.0.1

[client]
socket = /var/lib/mysql/mysql.sock

  10. After exiting nano, restart mysqld:

    $ systemctl restart mysqld

Installing and configuring Tarantool

In this section, you install Tarantool and set up spaces for replication.

  1. Go to the Download page and follow the installation instructions.

  2. Install the tt CLI utility.

  3. Create a new tt environment in the current directory using the tt init command.

  4. In the /etc/tarantool/instances.available/mysql directory, create the tt instance configuration files:

    • config.yaml – specifies the following configuration

      app:
  file: 'myapp.lua'

groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'

    • instances.yml – specifies instances to run in the current environment

      instance001:

    • myapp.lua – contains a Lua script with an application to load

      box.schema.user.grant('guest', 'read,write,execute', 'universe')

local function bootstrap()
    if not box.space.mysqldaemon then
        s = box.schema.space.create('mysqldaemon')
        s:create_index('primary',
                { type = 'tree', parts = { 1, 'unsigned' }, if_not_exists = true })
    end
    if not box.space.mysqldata then
        t = box.schema.space.create('mysqldata')
        t:create_index('primary',
                { type = 'tree', parts = { 1, 'unsigned' }, if_not_exists = true })
    end
end
bootstrap()

    For details, see the Configuration section.

  5. Inside the instances.enabled directory of the created tt environment, create a symlink (mysql) to the directory from the previous step:

    $ ln -s /etc/tarantool/instances.available/mysql mysql

  6. Next, start up the Lua program with tt, the Tarantool command-line utility:

    $ tt start mysql

  7. Enter the Tarantool instance:

    $ tt connect mysql:instance001

  8. Check that the target spaces were successfully created:

    mysql:instance001> box.space._space:select()

    At the bottom, you will see mysqldaemon and mysqldata spaces. Then exit with «CTRL+C».

Setting up the replicator

MySQL and Tarantool are now set up. You can proceed to configure the replicator.

  1. Edit the replicatord.yml file in the main tarantool-mysql-replication directory:

    nano replicatord.yml

  2. Change the entire file as follows. Don’t forget to add your MySQL password and set the appropriate user:

    mysql:
    host: 127.0.0.1
    port: 3306
    user: root
    password:
    connect_retry: 15 # seconds

tarantool:
    host: 127.0.0.1:3301
    binlog_pos_space: 512
    binlog_pos_key: 0
    connect_retry: 15 # seconds
    sync_retry: 1000 # milliseconds

mappings:
 - database: menagerie
   table: pet
   columns: [ id, name2, owner, species ]
   space: 513
   key_fields:  [ 0 ]
   # insert_call: function_name
   # update_call: function_name
   # delete_call: function_name

  3. Copy replicatord.yml to the location where systemd looks for it:

    $ cp replicatord.yml /usr/local/etc/replicatord.yml

  4. Next, start up the replicator:

    $ systemctl start replicatord

  5. Enter the Tarantool instance:

    $ tt connect mysql:instance001

  6. Do a select on the mysqldata space. The replicated content from MySQL looks the following way:

    mysql:instance001> box.space.mysqldata:select()
---
- - [1, 'Fluffy', 'Harold', 'cat']
  - [2, 'Claws', 'Gwen', 'cat']
  - [3, 'Buffy', 'Harold', 'dog']
  - [4, 'Fang', 'Benny', 'dog']
  - [5, 'Bowser', 'Diane', 'dog']
  - [6, 'Chirpy', 'Gwen', 'bird']
  - [7, 'Whistler', 'Gwen', 'bird']
  - [8, 'Slim', 'Benny', 'snake']
  - [9, 'Puffball', 'Diane', 'hamster']

Testing the replication

In this section, you enter a record into MySQL and check that the record is replicated to Tarantool. To do this:

  1. Exit the Tarantool instance with CTRL-D.

  2. Insert a record into MySQL:

    mysql -u root -p
USE menagerie;
INSERT INTO pet(name2, owner, species) VALUES ('Spot', 'Brad', 'dog');
QUIT

  3. In the terminal, enter the Tarantool instance:

    $ tt connect mysql:instance001

  4. To see the replicated data in Tarantool, run the following command:

    mysql:instance001> box.space.mysqldata:select()

Транзакции

Transactions allow users to perform multiple operations atomically.

For more information on how transactions work in Tarantool, see the following sections:

Transaction model

Overview

The transaction model of Tarantool corresponds to the properties ACID (atomicity, consistency, isolation, durability).

Tarantool has two modes of transaction behavior:

Each transaction in Tarantool is executed in a single fiber on a single thread, sees a consistent database state and commits all changes atomically.

All transaction changes are written to the WAL (Write Ahead Log) in a single batch in a specific order at the time of the commit. If needed, transaction changes can also be rolled back – completely or to a specified savepoint.

Therefore, every transaction in Tarantool has the highest transaction isolation level – serializable.

Isolation level

By default, the isolation level of Tarantool is serializable. The exception is a failure during writing to the WAL, which can occur, for example, when the disk space is over. In this case, the isolation level of the concurrent read transaction would be read-committed.

The MVСС mode provides several options that enable you to tune the visibility behavior during transaction execution.

Read-committed

The read-committed isolation level makes visible all transactions that started commit (box.commit() was called).

  • Write transactions with reads

    Manual usage of read-committed for write transactions with reads is completely safe, as this transaction will eventually result in a commit. If a previous transactions fails, this transaction will inevitably fail as well due to the serializable isolation level.

  • Read transactions

    Manual usage of read-committed for read transactions may be unsafe, as it may lead to phantom reads.

Read-confirmed

The read-confirmed isolation level makes visible all transactions that finished the commit (box.commit() was returned). This means that new data is already on disk or even on other replicas.

  • Read transactions

    The use of read-confirmed is safe for read transactions given that data is on disk (for asynchronous replication) or even in other replicas (for synchronous replication).

  • Write transactions

    To achieve serializable, any write transaction should read all data that has already been committed. Otherwise, it may conflict when it reaches its commit.

Linearizable read

Linearizability of read operations implies that if a response for a write request arrived earlier than a read request was made, this read request should return the results of the write request. When called with linearizable, box.begin() yields until the instance receives enough data from remote peers to be sure that the transaction is linearizable.

Linearizable transactions may only perform requests to the following memtx space types:

A linearizable transaction can fail with an error in the following cases:

  • If the node can’t contact enough remote peers to determine which data is committed.
  • If the data isn’t received during the timeout specified in box.begin().

Примечание

To start a linearizable transaction, the node should be the replication source for at least N - Q + 1 remote replicas. Here N is the count of registered nodes in the cluster and Q is replication_synchro_quorum. So, for example, you can’t perform a linearizable transaction on anonymous replicas because they can’t be the source of replication for other nodes.

Best-effort (default)

To minimize the possibility of conflicts, MVCC uses what is called best-effort visibility:

This inevitably leads to the serializable isolation level. Since there is no option for MVCC to analyze the whole transaction to make a decision, it makes the choice on the first operation.

Примечание

If the serializable isolation level becomes unreachable, the transaction is marked as «conflicted» and rolled back.

Thread model

Main threads

The thread model assumes that a query received by Tarantool via network is processed with three operating system threads:

  1. The network thread (or threads) on the server side receives the query, parses the statement, checks if it is correct, and then transforms it into a special structure – a message containing an executable statement and its options.

  2. The network thread sends this message to the instance’s transaction processor thread (TX thread) via a lock-free message bus. Lua programs are executed directly in the transaction processor thread, and do not need to be parsed and prepared.

    The TX thread either uses a space index to find and update the tuple, or executes a stored function that performs a data operation.

  3. The execution of the operation results in a message to the write-ahead logging (WAL) thread used to commit the transaction and the fiber executing the transaction is suspended. When the transaction results in a COMMIT or ROLLBACK, the following actions are taken:

    • The WAL thread responds with a message to the TX thread.
    • The fiber executing the transaction is resumed to process the result of the transaction.
    • The result of the fiber execution is passed to the network thread, and the network thread returns the result to the client.

Примечание

There is only one TX thread in Tarantool. Some users are used to the idea that there can be multiple threads working on the database. For example, thread #1 reads a row #x while thread #2 writes a row #y. With Tarantool this does not happen. Only the TX thread can access the database, and there is only one TX thread for each Tarantool instance.

The TX thread can handle many fibers – a set of computer instructions that can contain «yield» signals. The TX thread executes all computer instructions up to a yield signal, and then switches to execute the instructions of another fiber.

Yields must happen, otherwise the TX thread would be permanently stuck on the same fiber.

Supplementary threads

There are also several supplementary threads that serve additional capabilities:

Transaction mode: default

By default, Tarantool does not allow «yielding» inside a memtx transaction and the transaction manager is disabled. This allows fast atomic transactions without conflicts, but brings some limitations:

To learn how to enable yielding inside a memtx transaction, see Transaction mode: MVCC.

To switch back to the default mode, disable the transaction manager:

box.cfg { memtx_use_mvcc_engine = false }

Transaction mode: MVCC

Since version 2.6.1, Tarantool has another transaction behavior mode that allows «yielding» inside a memtx transaction. This is controlled by the transaction manager.

This mode allows concurrent transactions but may cause conflicts. You can use this mode on the memtx storage engine. The vinyl storage engine also supports MVCC mode, but has a different implementation.

Примечание

Currently, you cannot use several different storage engines within one transaction.

Transaction manager

The transaction manager is designed to isolate concurrent transactions and provides a serializable transaction isolation level. It consists of two parts:

The transaction manager also provides a non-classical snapshot isolation level – this snapshot is not necessarily tied to the start time of the transaction, like the classical snapshot where a transaction can get a consistent snapshot of the database. The conflict manager decides if and when each transaction gets which snapshot. This avoids some conflicts compared to the classic snapshot isolation approach.

Предупреждение

Currently, the isolation level of BITSET and RTREE indexes in MVCC transaction mode is read-committed (not serializable, as stated). If a transaction uses these indexes, it can read committed or confirmed data (depending on the isolation level). However, the indexes are subject to different anomalies that can make them unserializable.

Enabling the transaction manager

By default, the transaction manager is disabled. Use the memtx_use_mvcc_engine option to enable it via box.cfg.

box.cfg{memtx_use_mvcc_engine = true}

Setting the transaction isolation level

The transaction manager has the following options for the transaction isolation level:

  • best-effort (default)
  • read-committed
  • read-confirmed
  • linearizable (only for a specific transaction)

Using best-effort as the default option allows MVCC to consider the actions of transactions independently and determine the best isolation level for them. It increases the probability of successful completion of the transaction and helps to avoid possible conflicts.

To set another default isolation level, for example, read-committed, use the following command:

box.cfg { txn_isolation = 'read-committed' }

Note that the linearizable isolation level can’t be set as default and can be used for a specific transaction only. You can set an isolation level for a specific transaction in its box.begin() call:

box.begin({ txn_isolation = 'best-effort' })

In this case, you can also use the default option. It sets the transaction’s isolation level to the one set in box.cfg.

Примечание

For autocommit transactions (actions with a statement without explicit box.begin/box.commit calls) there is a rule:

  • Read-only transactions (for example, select) are performed with read-confirmed.
  • All other transactions (for example, replace) are performed with read-committed.

You can also set the isolation level in the net.box stream:begin() method and IPROTO_BEGIN binary protocol request.

Choosing the better option depends on whether you have conflicts or not. If you have many conflicts, you should set a different option or use the default transaction mode.

Examples with MVCC enabled and disabled

Create a file init.lua, containing the following:

fiber = require 'fiber'

box.cfg{ listen = '127.0.0.1:3301', memtx_use_mvcc_engine = false }
box.schema.user.grant('guest', 'super', nil, nil, {if_not_exists = true})

tickets = box.schema.create_space('tickets', { if_not_exists = true })
tickets:format({
    { name = "id", type = "number" },
    { name = "place", type = "number" },
})
tickets:create_index('primary', {
    parts = { 'id' },
    if_not_exists = true
})

Connect to the instance using the tt connect command:

tt connect 127.0.0.1:3301

Then try to execute the transaction with yield inside:

box.atomic(function() tickets:replace{1, 429} fiber.yield() tickets:replace{2, 429} end)

You will receive an error message:

---
- error: Transaction has been aborted by a fiber yield
...

Also, if you leave a transaction open while returning from a request, you will get an error message:

127.0.0.1:3301> box.begin()
    ⨯ Failed to execute command: Transaction is active at return from function

Change memtx_use_mvcc_engine to true, restart Tarantool, and try again:

127.0.0.1:3301> box.atomic(function() tickets:replace{1, 429} fiber.yield() tickets:replace{2, 429} end)
---
...

Now check if this transaction was successful:

127.0.0.1:3301> box.space.tickets:select({}, {limit = 10})
---
- - [1, 429]
  - [2, 429]
...

Streams and interactive transactions

Since v. 2.10.0, IPROTO implements streams and interactive transactions that can be used when memtx_use_mvcc_engine is enabled on the server.

Stream

A stream supports multiplexing several transactions over one connection. Each stream has its own identifier, which is unique within the connection. All requests with the same non-zero stream ID belong to the same stream. All requests in a stream are executed strictly sequentially. This allows the implementation of interactive transactions. If the stream ID of a request is 0, it does not belong to any stream and is processed in the old way.

In net.box, a stream is an object above the connection that has the same methods but allows sequential execution of requests. The ID is automatically generated on the client side. If a user writes their own connector and wants to use streams, they must transmit the stream_id over the IPROTO protocol.

Unlike a thread, which involves multitasking and execution within a program, a stream transfers data via the protocol between a client and a server.

Interactive transaction

An interactive transaction is one that does not need to be sent in a single request. There are multiple ways to begin, commit, and roll back a transaction, and they can be mixed. You can use stream:begin(), stream:commit(), stream:rollback() or the appropriate stream methods – call, eval, or execute – using the SQL transaction syntax.

Let’s create a Lua client (client.lua) and run it with Tarantool:

local net_box = require 'net.box'
local conn = net_box.connect('127.0.0.1:3301')
local conn_tickets = conn.space.tickets
local yaml = require 'yaml'

local stream = conn:new_stream()
local stream_tickets = stream.space.tickets

-- Begin transaction over an iproto stream:
stream:begin()
print("Replaced in a stream\n".. yaml.encode(  stream_tickets:replace({1, 768}) ))

-- Empty select, the transaction was not committed.
-- You can't see it from the requests that do not belong to the
-- transaction.
print("Selected from outside of transaction\n".. yaml.encode(conn_tickets:select({}, {limit = 10}) ))

-- Select returns the previously inserted tuple
-- because this select belongs to the transaction:
print("Selected from within transaction\n".. yaml.encode(stream_tickets:select({}, {limit = 10}) ))

-- Commit transaction:
stream:commit()

-- Now this select also returns the tuple because the transaction has been committed:
print("Selected again from outside of transaction\n".. yaml.encode(conn_tickets:select({}, {limit = 10}) ))

os.exit()

Then call it and see the following output:

Replaced in a stream
--- [1, 768]
...

Selected from outside of transaction
---
- [1, 429]
- [2, 429]
...

Selected from within transaction
---
- [1, 768]
- [2, 429]
...

Selected again from outside of transaction
---
- [1, 768]
- [2, 429]
...```

Replication

Механизм репликации позволяет сразу многим экземплярам Tarantool работать с копиями одних и тех же баз данных. При этом все базы остаются в синхронизированном состоянии благодаря тому, что каждый экземпляр может сообщать другим экземплярам о совершенных им изменениях.

This section includes the following topics:

For practical guides to replication, see Replication tutorials. You can learn about bootstrapping a replica set, adding instances to the replica set, or removing them.

Архитектура механизма репликации

Механизм репликации

Overview

A pack of instances that operate on copies of the same databases makes up a replica set. Each instance in a replica set has a role: master or replica.

A replica gets all updates from the master by continuously fetching and applying its write-ahead log (WAL). Each record in the WAL represents a single Tarantool data-change request such as INSERT, UPDATE, or DELETE, and is assigned a monotonically growing log sequence number (LSN). In essence, Tarantool replication is row-based: each data-change request is fully deterministic and operates on a single tuple. However, unlike a classical row-based log, which contains entire copies of the changed rows, Tarantool’s WAL contains copies of the requests. For example, for UPDATE requests, Tarantool only stores the primary key of the row and the update operations to save space.

Примечание

WAL extensions available in Tarantool Enterprise Edition enable you to add auxiliary information to each write-ahead log record. This information might be helpful for implementing a CDC (Change Data Capture) utility that transforms a data replication stream.

The following are specifics of adding different types of information to the WAL:

  • Invocations of stored programs are not written to the WAL. Instead, records of the actual data-change requests, performed by the Lua code, are written to the WAL. This ensures that the possible non-determinism of Lua does not cause replication to go out of sync.
  • Data definition operations on temporary spaces (created with temporary = true), such as creating/dropping, adding indexes, and truncating, are written to the WAL, since information about temporary spaces is stored in non-temporary system spaces, such as box.space._space.
  • Data change operations on temporary spaces are not written to the WAL and are not replicated.
  • Data change operations on replication-local spaces (created with is_local = true) are written to the WAL but are not replicated.

To learn how to enable replication, check the Bootstrapping a replica set guide.

Replication stages

To create a valid initial state, to which WAL changes can be applied, every instance of a replica set requires a start set of checkpoint files, such as .snap files for memtx and .run files for vinyl. A replica goes through the following stages:

  1. Bootstrap (optional)

    When an entire replica set is bootstrapped for the first time, there is no master that could provide the initial checkpoint. In such a case, replicas connect to each other and elect a master. The master creates the starting set of checkpoint files and distributes them to all the other replicas. This is called an automatic bootstrap of a replica set.

  2. Join

    At this stage, a replica downloads the initial state from the master. The master register this replica in the box.space._cluster space. If join fails with a non-critical error, for example, ER_READONLY, ER_ACCESS_DENIED, or a network-related issue, an instance tries to find a new master to join.

    Примечание

    On subsequent connections, a replica downloads all changes happened after the latest local LSN (there can be many LSNs – each master has its own LSN).

  3. Follow

    At this stage, a replica fetches and applies updates from the master’s write-ahead log.

You can use the box.info.replication[n].upstream.status property to monitor the status of a replica.

Replica set and instance UUIDs

Each replica set is identified by a globally unique identifier, called the replica set UUID. The identifier is created by the master, which creates the very first checkpoint and is part of the checkpoint file. It is stored in the box.space._schema system space, for example:

tarantool> box.space._schema:select{'cluster'}
---
- - ['cluster', '6308acb9-9788-42fa-8101-2e0cb9d3c9a0']
...

Additionally, each instance in a replica set is assigned its own UUID, when it joins the replica set. It is called an instance UUID and is a globally unique identifier. The instance UUID is checked to ensure that instances do not join a different replica set, e.g. because of a configuration error. A unique instance identifier is also necessary to apply rows originating from different masters only once, that is, to implement multi-master replication. This is why each row in the write-ahead log, in addition to its log sequence number, stores the instance identifier of the instance on which it was created. But using a UUID as such an identifier would take too much space in the write-ahead log, thus a shorter integer number is assigned to the instance when it joins a replica set. This number is then used to refer to the instance in the write-ahead log. It is called instance ID. All identifiers are stored in the system space box.space._cluster, for example:

tarantool> box.space._cluster:select{}
---
- - [1, '88580b5c-4474-43ab-bd2b-2409a9af80d2']
...

Здесь ID экземпляра – 1 (уникальный номер в рамках набора реплик), а UUID экземпляра – 88580b5c-4474-43ab-bd2b-2409a9af80d2 (глобально уникальный).

Использование идентификаторов экземпляра также полезно для отслеживания состояния всего набора реплик. Например, box.info.vclock описывает состояние репликации в отношении каждого подключенного узла.

tarantool> box.info.vclock
---
- {1: 827, 2: 584}
...

Here vclock contains log sequence numbers (827 and 584) for instances with instance IDs 1 and 2.

If required, you can explicitly specify the instance and the replica set UUID values rather than letting Tarantool generate them. To learn more, see the replicaset_uuid configuration parameter description.

Роли в репликации: мастер и реплика

Конфигурационный параметр read_only определяет роль в репликации (мастер или реплика). Рекомендованная роль для всех экземпляров в наборе реплик, кроме одного – «read-only» (реплика).

В конфигурации мастер-реплика каждое изменение, сделанное на мастере, будет отображаться на репликах, но не наоборот.

../../../_images/mr-1m-2r-oneway.svg

Простой набор реплик с двумя экземплярами, один из которых является мастером и расположен на одной машине, а другой – реплика – расположен на другой машине, дает два преимущества:

В конфигурации мастер-мастер (которая также называется «многомастерной») каждое изменение на любом экземпляре будет также отображаться на другом.

../../../_images/mm-3m-mesh.svg

Восстановление после отказа в таком случае также будет преимуществом, а балансировка нагрузки улучшится, поскольку любой экземпляр может обрабатывать запросы и на чтение, и на запись. В то же время, при многомастерной конфигурации необходимо понимать гарантии репликации, которые обеспечивает асинхронный протокол, внедренный в Tarantool.

Многомастерная репликация Tarantool гарантирует, что каждое изменение на каждом мастере передается на все экземпляры и применяется только один раз. Изменения с одного экземпляра применяются в том же порядке, что и на исходном экземпляре. Однако изменения с разных экземпляров могут смешиваться и применяться в различном порядке на разных экземплярах. В определенных случаях это может привести к рассинхронизации.

Например, принимая, что проводятся только операции добавления данных в базу (т.е. она содержит только вставки), многомастерная конфигурация сработает хорошо. Если данные также удаляются, но порядок операций удаления на разных репликах не играет важной роли (например, DELETE используется для отсечения устаревших данных), то конфигурация мастер-мастер также безопасна.

UPDATE operations, however, can easily go out of sync. For example, assignment and increment are not commutative and may yield different results if applied in a different order on different instances.

В общем смысле, безопасно использовать репликацию мастер-мастер в Tarantool, если все изменения в базе данных являются коммутативными: конечный результат не зависит от порядка, в котором применяются изменения. Дополнительную информацию о бесконфликтных типах реплицируемых данных можно получить здесь.

Replication topologies: cascade, ring, and full mesh

Replication topology is set by the replication configuration parameter. The recommended topology is a full mesh because it makes potential failover easy.

Some database products offer cascading replication topologies: creating a replica on a replica. Tarantool does not recommend such a setup.

../../../_images/no-cascade.svg

Недостаток каскадного набора реплик заключается в том, что некоторые экземпляры не подключаются к другим экземплярам, поэтому не могут получать от них изменения. Одно важное изменение, которое следует передавать на все экземпляры в наборе реплик – запись в системный спейс box.space._cluster с UUID набора реплик. Не зная UUID набора реплик, мастер отклоняет подключения от таких экземпляров при изменении топологии репликации. Вот как это может произойти:

../../../_images/cascade-problem-1.svg

We have a chain of three instances. Instance #1 contains entries for instances #1 and #2 in its _cluster space. Instances #2 and #3 contain entries for instances #1, #2, and #3 in their _cluster spaces.

../../../_images/cascade-problem-2.svg

Now instance #2 is faulty. Instance #3 tries connecting to instance #1 as its new master, but the master refuses the connection since it has no entry, for example, #3.

Тем не менее, кольцевая топология поддерживается:

../../../_images/cascade-to-ring.svg

Поэтому если необходима каскадная топология, можно первоначально создать кольцо, чтобы все экземпляры знали UUID друг друга, а затем разъединить цепочку в необходимом месте.

Как бы то ни было, для репликации мастер-мастер рекомендуется полная ячеистая топология:

../../../_images/mm-3m-mesh.svg

В таком случае можно решить, где расположить экземпляры ячейки – в том же центре обработки данных или разместить в нескольких центрах. Tarantool будет автоматически следить за тем, что каждая строка применяется однократно на каждом экземпляре. Чтобы удалить экземпляр из ячейки после отказа, просто измените конфигурационный параметр replication.

Таким образом можно обеспечить доступность всего кластера в случае локального отказа, например отказа одного экземпляра в одном центре обработки данных, а также в случае отказа всего центра обработки данных.

Максимальное количество реплик в ячейке – 32.

Статус orphan (одиночный)

During box.cfg(), an instance tries to join all nodes listed in box.cfg.replication. If the instance does not succeed in connecting to the required number of nodes (see bootstrap_strategy), it switches to the orphan status.

Синхронная репликация

Общие сведения

По умолчанию репликация в Tarantool асинхронная: локальный коммит транзакции на мастере не означает, что эта транзакция будет сразу же выполнена на репликах. Если мастер сообщит клиенту об успешном выполнении операции, а потом прекратит работу и после отказа восстановится на реплике, то с точки зрения клиента транзакция пропадет.

Эту проблему решает синхронная репликация. Каждая синхронная транзакция проходит коммит лишь после репликации на некотором количестве экземпляров, и только тогда клиенту приходит ответ о завершении транзакции.

To enable synchronous replication, use the space_opts.is_sync option when creating or altering a space.

Синхронные и асинхронные транзакции

В Tarantool синхронную репликацию можно настроить для отдельных спейсов. Эта удобная функция позволит вам не потерять в производительности, если синхронная репликация нужна вам лишь изредка для изменения критически важных данных.

Если наряду с несколькими синхронными транзакциями, ожидающими репликации, совершается асинхронная транзакция, она блокируется синхронными. Коммиты при этом выполняются в той последовательности, в которой для каждой из транзакций вызывается метод box.commit(). Похожим образом работает обычная очередь асинхронных транзакций. Можно сформулировать правило коммитов: порядок коммитов соответствует порядку вызова box.commit() для каждой из транзакций, независимо от того, синхронные транзакции или асинхронные.

Если для одной из синхронных транзакций истечет время ожидания, эта транзакция будет отменена, а вместе с ней и все последующие транзакции в очереди на репликацию. Похожим образом отменяются и асинхронные транзакции при ошибке записи в WAL. Действует правило отмены: транзакции отменяются в порядке, обратном порядку вызова box.commit() для каждой из них, независимо от того, синхронные транзакции или асинхронные.

Асинхронная транзакция, заблокированная синхронной, не становится сама синхронной, а просто ожидает коммита синхронной транзакции. Как только это произойдет, асинхронная транзакция сразу сможет пройти коммит, не ожидая репликации.

Предупреждение

Будьте осторожны при одновременном использовании синхронных и асинхронных транзакций. Для асинхронных транзакций коммит засчитывается успешным даже в том случае, если нет соединения с другими узлами. Поэтому на старом leader-узле (владельце очереди синхронных транзакций) могут быть асинхронные транзакции, которые прошли коммит, но отсутствуют на других узлах набора реплик.

Когда предыдущий лидер снова становится доступен в наборе реплик, он начинает получать данные с нового лидера. В это же время остальные узлы в наборе реплик начинают получать данные со старого лидера, которых у них еще нет. Эти данные содержат и асинхронные транзакции, прошедшие коммит. В этот момент система выдаст ошибку ER_SPLIT_BRAIN, заставляя пользователя провести повторную настройку (rebootstrap) предыдущего лидера.

Ограничения и известные проблемы

До версии 2.5.2 способа настроить синхронную репликацию для существующих спейсов не было. Однако, начиная с версии 2.5.2, ее можно включить, вызвав метод space_object:alter({is_sync = true}).

Синхронные транзакции работают исключительно в топологии «мастер-реплика». В кластере может быть несколько реплик, в том числе анонимных, однако синхронные транзакции должен совершать только один узел.

Начиная с версии Tarantool 2.10.0, анонимные реплики не участвуют в кворуме.

Выборы лидера

В Tarantool, начиная с версии 2.6.1, есть встроенная функциональность для управления автоматическими выборами лидера (automated leader election) в наборе реплик. Подробности можно найти в соответствующей главе.

Автоматические выборы лидера

В Tarantool, начиная с версии 2.6.1, есть встроенная функциональность для управления автоматическими выборами лидера (automated leader election) в наборе реплик (replica set). Эта функциональность повышает отказоустойчивость систем на базе Tarantool и снижает зависимость от внешних инструментов для управления набором реплик.

To learn how to configure and monitor automated leader elections, check Managing leader elections.

Ниже описаны следующие темы:

Выборы лидера и синхронная репликация

В Tarantool используется модификация Raft — алгоритма синхронной репликации и автоматических выборов лидера. Полное описание алгоритма Raft можно прочитать в соответствующем документе.

Синхронная репликация и выборы лидера в Tarantool реализованы как две независимые подсистемы. Это означает, что можно настроить синхронную репликацию, а для выборов лидера использовать альтернативный алгоритм. Встроенный механизм выборов лидера, в свою очередь, не требует использования синхронных спейсов. Синхронной репликации посвящен этот раздел документации. Процесс выборов лидера описан ниже.

Примечание

The system behavior can be specified exactly according to the Raft algorithm. To do this:

Процесс выборов лидера

Автоматические выборы лидера в Tarantool гарантируют, что в каждый момент времени в наборе реплик будет максимум один лидер — узел, доступный для записи. Все остальные узлы будут принимать исключительно запросы на чтение.

Когда функция выборов включена, жизненный цикл набора реплик разделен на так называемые термы (term). Каждый терм описывается монотонно растущим числом. После первой загрузки узла значение его терма равно 1. Когда узел обнаруживает, что не является лидером и при этом лидера в наборе реплик уже какое-то время нет, он увеличивает значение своего терма и начинает новый тур выборов.

Выборы лидера происходят посредством голосования. Узел, начинающий выборы, голосует сам за себя и отправляет другим запросы на голос. Каждый экземпляр голосует за первый узел, от которого пришел такой запрос, и далее в течение всего терма ожидает избрания лидера, не выполняя никаких действий.

The node that collected a quorum of votes defined by the replication.synchro_quorum parameter becomes the leader and notifies other nodes about that. Also, a split vote can happen when no nodes received a quorum of votes. In this case, after a random timeout, each node increases its term and starts a new election round if no new vote request with a greater term arrives during this time. Eventually, a leader is elected.

If any unfinalized synchronous transactions are left from the previous leader, the new leader finalizes them automatically.

All the non-leader nodes are called followers. The nodes that start a new election round are called candidates. The elected leader sends heartbeats to the non-leader nodes to let them know it is alive.

In case there are no heartbeats for the period of replication.timeout * 4, a non-leader node starts a new election if the following conditions are met:

Примечание

A cluster member considers the leader node to be alive if the member received heartbeats from the leader at least once during the replication.timeout * 4, and there are no replication errors (the connection is not broken due to timeout or due to an error).

Terms and votes are persisted by each instance to preserve certain Raft guarantees.

При голосовании узлы отдают предпочтение экземплярам, где сохранены самые новые данные. Поэтому, если прежний лидер перед тем, как стать недоступным, отправит кворуму реплик какую-либо информацию, она не будет потеряна.

When election is enabled, there must be connections between each node pair so as it would be the full mesh topology. This is needed because election messages for voting and other internal things need a direct connection between the nodes.

In the classic Raft algorithm, a leader doesn’t track its connectivity to the rest of the cluster. Once the leader is elected, it considers itself in the leader position until receiving a new term from another cluster node. This can lead to a split situation if the other nodes elect a new leader upon losing the connectivity to the previous one.

The issue is resolved in Tarantool version 2.10.0 by introducing the leader fencing mode. The mode can be switched by the replication.election_fencing_mode configuration parameter. When the fencing is set to soft or strict, the leader resigns its leadership if it has less than replication.synchro_quorum of alive connections to the cluster nodes. The resigning leader receives the status of a follower in the current election term and becomes read-only. Leader fencing can be turned off by setting the replication.election_fencing_mode configuration parameter to off.

In soft mode, a connection is considered dead if there are no responses for 4 * replication.timeout seconds both on the current leader and the followers.

In strict mode, a connection is considered dead if there are no responses for 2 * replication.timeout seconds on the current leader and for 4 * replication.timeout seconds on the followers. This improves chances that there is only one leader at any time.

Fencing applies to the instances that have the replication.election_mode set to «candidate» or «manual».

There can still be a situation when a replica set has two leaders working independently (so-called split-brain). It can happen, for example, if a user mistakenly lowered the replication.synchro_quorum below N / 2 + 1. In this situation, to preserve the data integrity, if an instance detects the split-brain anomaly in the incoming replication data, it breaks the connection with the instance sending the data and writes the ER_SPLIT_BRAIN error in the log.

Eventually, there will be two sets of nodes with the diverged data, and any node from one set is disconnected from any node from the other set with the ER_SPLIT_BRAIN error.

Once noticing the error, a user can choose any representative from each of the sets and inspect the data on them. To correlate the data, the user should remove it from the nodes of one set, and reconnect them to the nodes from the other set that have the correct data.

Любой узел, участвующий в процессе выборов, реплицирует данные только с последнего избранного лидера. Это позволяет избежать ситуации, в которой прежний лидер после выборов нового все еще пытается отправлять изменения на реплики.

Числовые значения термов также выполняют функцию своеобразного фильтра. Например, если на двух узлах включена функция выборов и значение терма node1 меньше значения терма node2, то узел node2 не будет принимать транзакций от узла node1.

Managing leader elections

Configuration

replication:
  election_mode: <string>
  election_fencing_mode: <string>
  election_timeout: <seconds>
  timeout: <seconds>
  synchro_quorum: <count>

It is important to know that being a leader is not the only requirement for a node to be writable. The leader should also satisfy the following requirements:

  • The database.mode option is set to rw.
  • The leader shouldn’t be in the orphan state.

Nothing prevents you from setting the database.mode option to ro, but the leader won’t be writable then. The option doesn’t affect the election process itself, so a read-only instance can still vote and become a leader.

Monitoring

To monitor the current state of a node regarding the leader election, use the box.info.election function.

Example:

tarantool> box.info.election
---
- state: follower
  vote: 0
  leader: 0
  term: 1
...

The Raft-based election implementation logs all its actions with the RAFT: prefix. The actions are new Raft message handling, node state changing, voting, and term bumping.

Important notes

Leader election doesn’t work correctly if the election quorum is set to less or equal than <cluster size> / 2. In that case, a split vote can lead to a state when two leaders are elected at once.

For example, suppose there are five nodes. When the quorum is set to 2, node1 and node2 can both vote for node1. node3 and node4 can both vote for node5. In this case, node1 and node5 both win the election. When the quorum is set to the cluster majority, that is (<cluster size> / 2) + 1 or greater, the split vote is impossible.

That should be considered when adding new nodes. If the majority value is changing, it’s better to update the quorum on all the existing nodes before adding a new one.

Also, the automated leader election doesn’t bring many benefits in terms of data safety when used without synchronous replication. If the replication is asynchronous and a new leader gets elected, the old leader is still active and considers itself the leader. In such case, nothing stops it from accepting requests from clients and making transactions. Non-synchronous transactions are successfully committed because they are not checked against the quorum of replicas. Synchronous transactions fail because they are not able to collect the quorum – most of the replicas reject these old leader’s transactions since it is not a leader anymore.

Supervised failover

Enterprise Edition

Supervised failover is supported by the Enterprise Edition only.

Example on GitHub: supervised_failover

Tarantool provides the ability to control leadership in a replica set using an external failover coordinator. A failover coordinator reads a cluster configuration from a file or an etcd-based configuration storage, polls instances for their statuses, and appoints a leader for each replica set depending on the availability and health of instances.

To increase fault tolerance, you can run two or more failover coordinators. In this case, an etcd cluster provides synchronization between coordinators.


Supervised failover

Overview

The main steps of using an external failover coordinator for a newly configured cluster might look as follows:

  1. Configure a cluster to work with an external coordinator. The main step is setting the replication.failover option to supervised for all replica sets that should be managed by the external coordinator.
  2. Start a configured cluster. When an external coordinator is still not running, instances in a replica set start in the following modes:
    • If a replica set is already bootstrapped, all instances are started in read-only mode.
    • If a replica set is not bootstrapped, one instance is started in read-write mode.
  3. Start a failover coordinator. You can start two or more failover coordinators to increase fault tolerance. In this case, one coordinator is active and others are passive.

Once a cluster and failover coordinators are up and running, a failover coordinator appoints one instance to be a master if there is no master instance in a replica set. Then, the following events may occur:

Примечание

Note that a failover coordinator doesn’t work with replica sets with two or more read-write instances. In this case, a coordinator logs a warning to stdout and doesn’t perform any appointments.

Appointing a new master instance

After a master instance has been appointed, a failover coordinator monitors the statuses of all instances in a replica set by sending requests each probe_interval seconds. For the master instance, the coordinator maintains a read-write mode deadline, which is renewed periodically each renew_interval seconds. If all attempts to renew the deadline fail during the specified time interval (lease_interval), the master switches to read-only mode. Then, the coordinator appoints a new instance as the master.

Примечание

Anonymous replicas are not considered as candidates to be a master.

If a remote etcd-based storage is used to maintain the state of failover coordinators, you can also perform a manual failover.

Active and passive coordinators

To increase fault tolerance, you can run two or more failover coordinators. In this case, only one coordinator is active and used to control leadership in a replica set. Other coordinators are passive and don’t perform any read-write appointments.

To maintain the state of coordinators, Tarantool uses a stateboard – a remote etcd-based storage. This storage uses the same connection settings as a centralized etcd-based configuration storage. If a cluster configuration is stored in the <prefix>/config/* keys in etcd, the failover coordinator looks into <prefix>/failover/* for its state. Here are a few examples of keys used for different purposes:

  • <prefix>/failover/info/by-uuid/<uuid>: contains a state of a failover coordinator identified by the specified uuid.
  • <prefix>/failover/active/lock: a unique identifier (UUID) of an active failover coordinator.
  • <prefix>/failover/active/term: a kind of fencing token allowing to have an order in which coordinators become active (took the lock) over time.
  • <prefix>/failover/command/<id>: a key used to perform a manual failover.

Configuring a cluster

To configure a cluster to work with an external failover coordinator, follow the steps below:

  1. (Optional) If you need to run several failover coordinators to increase fault tolerance, set up an etcd-based configuration storage, as described in Centralized configuration storages.

  2. Set the replication.failover option to supervised:

    replication:
  failover: supervised

  3. Grant a user used for replication permissions to execute the failover.execute function:

    credentials:
  users:
    replicator:
      password: 'topsecret'
      roles: [ replication ]
      privileges:
      - permissions: [ execute ]
        functions: [ 'failover.execute' ]

  4. Create the failover.execute function in the application code. For example, you can create a custom role for this purpose:

    -- supervised_instance.lua --
return {
    validate = function()
    end,
    apply = function()
        if box.info.ro then
            return
        end
        local func_name = 'failover.execute'
        local opts = { if_not_exists = true }
        box.schema.func.create(func_name, opts)
    end,
    stop = function()
        if box.info.ro then
            return
        end
        local func_name = 'failover.execute'
        if not box.schema.func.exists(func_name) then
            return
        end
        box.schema.func.drop(func_name)
    end,
}

    Then, you need to enable this role for all storage instances:

    roles: [ 'supervised_instance' ]

  5. (Optional) Configure options that control how a failover coordinator operates in the failover section:

    failover:
  probe_interval: 5
  lease_interval: 15
  renew_interval: 5
  stateboard:
    keepalive_interval: 5
    renew_interval: 1

You can find the full example on GitHub: supervised_failover.

Starting a failover coordinator

To start a failover coordinator, you need to execute the tarantool command with the failover option. This command accepts the path to a cluster configuration file:

tarantool --failover --config instances.enabled/supervised_failover/config.yaml

If a cluster’s configuration is stored in etcd, the config.yaml file contains connection options for the etcd storage.

You can run two or more failover coordinators to increase fault tolerance. In this case, only one coordinator is active and used to control leadership in a replica set. Learn more from Active and passive coordinators.

Performing manual failover

If an etcd-based storage is used to maintain the state of failover coordinators, you can perform a manual failover. External tools can use the <prefix>/failover/command/<id> key to choose a new master. For example, the tt utility provides the tt cluster failover command for managing a supervised failover.

Replication tutorials

Master-replica: manual failover

Example on GitHub: manual_leader

This tutorial shows how to configure and work with a replica set with manual failover.

Prerequisites

Before starting this tutorial:

  1. Install the tt utility.

  2. Create a tt environment in the current directory by executing the tt init command.

  3. Inside the instances.enabled directory of the created tt environment, create the manual_leader directory.

  4. Inside instances.enabled/manual_leader, create the instances.yml and config.yaml files:

    • instances.yml specifies instances to run in the current environment and should look like this:

      instance001:
instance002:

    • The config.yaml file is intended to store a replica set configuration.

Configuring a replica set

This section describes how to configure a replica set in config.yaml.

Step 1: Configuring a failover mode

First, set the replication.failover option to manual:

replication:
  failover: manual

Step 2: Defining a replica set topology

Define a replica set topology inside the groups section:

  • The leader option sets instance001 as a replica set leader.
  • The iproto.listen option specifies an address used to listen for incoming requests and allows replicas to communicate with each other.
groups:
  group001:
    replicasets:
      replicaset001:
        leader: instance001
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
          instance002:
            iproto:
              listen:
              - uri: '127.0.0.1:3302'

Step 3: Creating a user for replication

In the credentials section, create the replicator user with the replication role:

credentials:
  users:
    replicator:
      password: 'topsecret'
      roles: [replication]

Step 4: Specifying advertise URIs

Set iproto.advertise.peer to advertise the current instance to other replica set members:

iproto:
  advertise:
    peer:
      login: replicator

Resulting configuration

The resulting replica set configuration should look as follows:

credentials:
  users:
    replicator:
      password: 'topsecret'
      roles: [replication]

iproto:
  advertise:
    peer:
      login: replicator

replication:
  failover: manual

groups:
  group001:
    replicasets:
      replicaset001:
        leader: instance001
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
          instance002:
            iproto:
              listen:
              - uri: '127.0.0.1:3302'

Working with a replica set

Starting instances

  1. After configuring a replica set, execute the tt start command from the tt environment directory:

    $ tt start manual_leader
   • Starting an instance [manual_leader:instance001]...
   • Starting an instance [manual_leader:instance002]...

  2. Check that instances are in the RUNNING status using the tt status command:

    $ tt status manual_leader
INSTANCE                      STATUS      PID   MODE
manual_leader:instance001     RUNNING     15272 RW
manual_leader:instance002     RUNNING     15273 RO

Checking a replica set status

  1. Connect to instance001 using tt connect:

    $ tt connect manual_leader:instance001
   • Connecting to the instance...
   • Connected to manual_leader:instance001

  2. Make sure that the instance is in the running state by executing box.info.status:

    manual_leader:instance001> box.info.status
---
- running
...

  3. Check that the instance is writable using box.info.ro:

    manual_leader:instance001> box.info.ro
---
- false
...

  4. Execute box.info.replication to check a replica set status. For instance002, upstream.status and downstream.status should be follow.

    manual_leader:instance001> box.info.replication
---
- 1:
    id: 1
    uuid: 9bb111c2-3ff5-36a7-00f4-2b9a573ea660
    lsn: 7
    name: instance001
  2:
    id: 2
    uuid: 4cfa6e3c-625e-b027-00a7-29b2f2182f23
    lsn: 0
    upstream:
      status: follow
      idle: 0.3893879999996
      peer: replicator@127.0.0.1:3302
      lag: 0.00028800964355469
    name: instance002
    downstream:
      status: follow
      idle: 0.37777199999982
      vclock: {1: 7}
      lag: 0
...

    To see the diagrams that illustrate how the upstream and downstream connections look, refer to Monitoring a replica set.

Adding data

To check that a replica (instance002) gets all updates from the master, follow the steps below:

  1. On instance001, create a space and add data as described in CRUD operation examples.

  2. Open the second terminal, connect to instance002 using tt connect, and use the select operation to make sure data is replicated.

  3. Check that box.info.vclock values are the same on both instances:

    • instance001:

      manual_leader:instance001> box.info.vclock
---
- {1: 21}
...

    • instance002:

      manual_leader:instance002> box.info.vclock
---
- {1: 21}
...

    Примечание

    Note that a vclock value might include the 0 component that is related to local space operations and might differ for different instances in a replica set.

Adding instances

This section describes how to add a new replica to a replica set.

Adding an instance to the configuration

  1. Add instance003 to the instances.yml file:

    instance001:
instance002:
instance003:

  2. Add instance003 with the specified iproto.listen option to the config.yaml file:

    groups:
  group001:
    replicasets:
      replicaset001:
        leader: instance001
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
          instance002:
            iproto:
              listen:
              - uri: '127.0.0.1:3302'
          instance003:
            iproto:
              listen:
              - uri: '127.0.0.1:3303'

Starting an instance

  1. Open the third terminal to work with a new instance. Start instance003 using tt start:

    $ tt start manual_leader:instance003
   • Starting an instance [manual_leader:instance003]...

  2. Check a replica set status using tt status:

    $ tt status manual_leader
INSTANCE                      STATUS      PID   MODE
manual_leader:instance001     RUNNING     15272 RW
manual_leader:instance002     RUNNING     15273 RO
manual_leader:instance003     RUNNING     15551 RO

Reloading configuration

After you added instance003 to the configuration and started it, you need to reload configurations on all instances. This is required to allow instance001 and instance002 to get data from the new instance in case it becomes a master.

  1. Connect to instance003 using tt connect:

    $ tt connect manual_leader:instance003
   • Connecting to the instance...
   • Connected to manual_leader:instance001

  2. Reload configurations on all three instances using the reload() function provided by the config module:

    • instance001:

      manual_leader:instance001> require('config'):reload()
---
...

    • instance002:

      manual_leader:instance002> require('config'):reload()
---
...

    • instance003:

      manual_leader:instance003> require('config'):reload()
---
...

  3. Execute box.info.replication to check a replica set status. Make sure that upstream.status and downstream.status are follow for instance003.

    manual_leader:instance001> box.info.replication
---
- 1:
    id: 1
    uuid: 9bb111c2-3ff5-36a7-00f4-2b9a573ea660
    lsn: 21
    name: instance001
  2:
    id: 2
    uuid: 4cfa6e3c-625e-b027-00a7-29b2f2182f23
    lsn: 0
    upstream:
      status: follow
      idle: 0.052655000000414
      peer: replicator@127.0.0.1:3302
      lag: 0.00010204315185547
    name: instance002
    downstream:
      status: follow
      idle: 0.09503500000028
      vclock: {1: 21}
      lag: 0.00026917457580566
  3:
    id: 3
    uuid: 9a3a1b9b-8a18-baf6-00b3-a6e5e11fd8b6
    lsn: 0
    upstream:
      status: follow
      idle: 0.77522099999987
      peer: replicator@127.0.0.1:3303
      lag: 0.0001838207244873
    name: instance003
    downstream:
      status: follow
      idle: 0.33186100000012
      vclock: {1: 21}
      lag: 0
        ...

Performing manual failover

This section shows how to perform manual failover and change a replica set leader.

Switching instances to read-only mode

  1. In the config.yaml file, change the replica set leader from instance001 to null:

    replicaset001:
  leader: null

  2. Reload configurations on all three instances using config:reload() and check that instances are in read-only mode. The example below shows how to do this for instance001:

    manual_leader:instance001> require('config'):reload()
---
...
manual_leader:instance001> box.info.ro
---
- true
...
manual_leader:instance001> box.info.ro_reason
---
- config
...

  3. Make sure that box.info.vclock values are the same on all instances:

    • instance001:

      manual_leader:instance001> box.info.vclock
---
- {1: 21}
...

    • instance002:

      manual_leader:instance002> box.info.vclock
---
- {1: 21}
...

    • instance003:

      manual_leader:instance003> box.info.vclock
---
- {1: 21}
...

Configuring a new leader

  1. Change a replica set leader in config.yaml to instance002:

    replicaset001:
  leader: instance002

  2. Reload configuration on all instances using config:reload().

  3. Make sure that instance002 is a new master:

    manual_leader:instance002> box.info.ro
---
- false
...

  4. Check replication status using box.info.replication.

Removing instances

This section describes the process of removing an instance from a replica set.

Before removing an instance, make sure it is in read-only mode. If the instance is a master, perform manual failover.

Disconnecting an instance

  1. Clear the iproto option for instance003 by setting its value to {}:

    instance003:
  iproto: {}

  2. Reload configurations on instance001 and instance002:

    • instance001:

      manual_leader:instance001> require('config'):reload()
---
...

    • instance002:

      manual_leader:instance002> require('config'):reload()
---
...

  3. Check that the upstream section is missing for instance003 by executing box.info.replication[3]:

    manual_leader:instance001> box.info.replication[3]
---
- id: 3
  uuid: 9a3a1b9b-8a18-baf6-00b3-a6e5e11fd8b6
  lsn: 0
  downstream:
    status: follow
    idle: 0.4588760000006
    vclock: {1: 21}
    lag: 0
  name: instance003
...

Stopping an instance

  1. Stop instance003 using the tt stop command:

    $ tt stop manual_leader:instance003
   • The Instance manual_leader:instance003 (PID = 15551) has been terminated.

  2. Check that downstream.status is stopped for instance003:

    manual_leader:instance001> box.info.replication[3]
---
- id: 3
  uuid: 9a3a1b9b-8a18-baf6-00b3-a6e5e11fd8b6
  lsn: 0
  downstream:
    status: stopped
    message: 'unexpected EOF when reading from socket, called on fd 27, aka 127.0.0.1:3301,
      peer of 127.0.0.1:54185: Broken pipe'
    system_message: Broken pipe
  name: instance003
...

Removing an instance from the configuration

  1. Remove instance003 from the instances.yml file:

    instance001:
instance002:

  2. Remove instance003 from config.yaml:

    instances:
  instance001:
    iproto:
      listen:
      - uri: '127.0.0.1:3301'
  instance002:
    iproto:
      listen:
      - uri: '127.0.0.1:3302'

  3. Reload configurations on instance001 and instance002:

    • instance001:

      manual_leader:instance001> require('config'):reload()
---
...

    • instance002:

      manual_leader:instance002> require('config'):reload()
---
...

Removing an instance from the „_cluster“ space

To remove an instance from the replica set permanently, it should be removed from the box.space._cluster system space:

  1. Select all the tuples in the box.space._cluster system space:

    manual_leader:instance002> box.space._cluster:select{}
---
- - [1, '9bb111c2-3ff5-36a7-00f4-2b9a573ea660', 'instance001']
  - [2, '4cfa6e3c-625e-b027-00a7-29b2f2182f23', 'instance002']
  - [3, '9a3a1b9b-8a18-baf6-00b3-a6e5e11fd8b6', 'instance003']
...

  2. Delete a tuple corresponding to instance003:

    manual_leader:instance002> box.space._cluster:delete(3)
---
- [3, '9a3a1b9b-8a18-baf6-00b3-a6e5e11fd8b6', 'instance003']
...

  3. Execute box.info.replication to check the health status:

    manual_leader:instance002> box.info.replication
---
- 1:
    id: 1
    uuid: 9bb111c2-3ff5-36a7-00f4-2b9a573ea660
    lsn: 21
    upstream:
      status: follow
      idle: 0.73316000000159
      peer: replicator@127.0.0.1:3301
      lag: 0.00016212463378906
    name: instance001
    downstream:
      status: follow
      idle: 0.7269320000014
      vclock: {2: 1, 1: 21}
      lag: 0.00083398818969727
  2:
    id: 2
    uuid: 4cfa6e3c-625e-b027-00a7-29b2f2182f23
    lsn: 1
    name: instance002
...

Master-replica: automated failover

Example on GitHub: auto_leader

This tutorial shows how to configure and work with a replica set with automated failover.

Prerequisites

Before starting this tutorial:

  1. Install the tt utility.

  2. Create a tt environment in the current directory by executing the tt init command.

  3. Inside the instances.enabled directory of the created tt environment, create the auto_leader directory.

  4. Inside instances.enabled/auto_leader, create the instances.yml and config.yaml files:

    • instances.yml specifies instances to run in the current environment and should look like this:

      instance001:
instance002:
instance003:

    • The config.yaml file is intended to store a replica set configuration.

Configuring a replica set

This section describes how to configure a replica set in config.yaml.

Step 1: Configuring a failover mode

First, set the replication.failover option to election:

replication:
  failover: election

Step 2: Defining a replica set topology

Define a replica set topology inside the groups section. The iproto.listen option specifies an address used to listen for incoming requests and allows replicas to communicate with each other.

groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
          instance002:
            iproto:
              listen:
              - uri: '127.0.0.1:3302'
          instance003:
            iproto:
              listen:
              - uri: '127.0.0.1:3303'

Step 3: Creating a user for replication

In the credentials section, create the replicator user with the replication role:

credentials:
  users:
    replicator:
      password: 'topsecret'
      roles: [replication]

Step 4: Specifying advertise URIs

Set iproto.advertise.peer to advertise the current instance to other replica set members:

iproto:
  advertise:
    peer:
      login: replicator

Resulting configuration

The resulting replica set configuration should look as follows:

credentials:
  users:
    replicator:
      password: 'topsecret'
      roles: [replication]

iproto:
  advertise:
    peer:
      login: replicator

replication:
  failover: election

groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
          instance002:
            iproto:
              listen:
              - uri: '127.0.0.1:3302'
          instance003:
            iproto:
              listen:
              - uri: '127.0.0.1:3303'

Working with a replica set

Starting instances

  1. After configuring a replica set, execute the tt start command from the tt environment directory:

    $ tt start auto_leader
   • Starting an instance [auto_leader:instance001]...
   • Starting an instance [auto_leader:instance002]...
   • Starting an instance [auto_leader:instance003]...

  2. Check that instances are in the RUNNING status using the tt status command:

    $ tt status auto_leader
INSTANCE                    STATUS      PID   MODE
auto_leader:instance001     RUNNING     24768 RO
auto_leader:instance002     RUNNING     24769 RW
auto_leader:instance003     RUNNING     24767 RO

Checking a replica set status

  1. Connect to instance001 using tt connect:

    $ tt connect auto_leader:instance001
   • Connecting to the instance...
   • Connected to auto_leader:instance001

  2. Check the instance state in regard to leader election using box.info.election. The output below shows that instance001 is a follower while instance002 is a replica set leader.

    auto_leader:instance001> box.info.election
---
- leader_idle: 0.77491499999815
  leader_name: instance002
  state: follower
  vote: 0
  term: 2
  leader: 1
...

  3. Check that instance001 is in read-only mode using box.info.ro:

    auto_leader:instance001> box.info.ro
---
- true
...

  4. Execute box.info.replication to check a replica set status. Make sure that upstream.status and downstream.status are follow for instance002 and instance003.

    auto_leader:instance001> box.info.replication
---
- 1:
    id: 1
    uuid: 4cfa6e3c-625e-b027-00a7-29b2f2182f23
    lsn: 9
    upstream:
      status: follow
      idle: 0.8257709999998
      peer: replicator@127.0.0.1:3302
      lag: 0.00012326240539551
    name: instance002
    downstream:
      status: follow
      idle: 0.81174199999805
      vclock: {1: 9}
      lag: 0
  2:
    id: 2
    uuid: 9bb111c2-3ff5-36a7-00f4-2b9a573ea660
    lsn: 0
    name: instance001
  3:
    id: 3
    uuid: 9a3a1b9b-8a18-baf6-00b3-a6e5e11fd8b6
    lsn: 0
    upstream:
      status: follow
      idle: 0.83125499999733
      peer: replicator@127.0.0.1:3303
      lag: 0.00010204315185547
    name: instance003
    downstream:
      status: follow
      idle: 0.83213399999659
      vclock: {1: 9}
      lag: 0
...

    To see the diagrams that illustrate how the upstream and downstream connections look, refer to Monitoring a replica set.

Adding data

To check that replicas (instance001 and instance003) get all updates from the master (instance002), follow the steps below:

  1. Connect to instance002 using tt connect:

    $ tt connect auto_leader:instance002
   • Connecting to the instance...
   • Connected to auto_leader:instance002

  2. Create a space and add data as described in CRUD operation examples.

  3. Use the select operation on instance001 and instance003 to make sure data is replicated.

  4. Check that the 1 component of box.info.vclock values are the same on all instances:

    • instance001:

      auto_leader:instance001> box.info.vclock
---
- {0: 1, 1: 32}
...

    • instance002:

      auto_leader:instance002> box.info.vclock
---
- {0: 1, 1: 32}
...

    • instance003:

      auto_leader:instance003> box.info.vclock
---
- {0: 1, 1: 32}
...

Примечание

Note that a vclock value might include the 0 component that is related to local space operations and might differ for different instances in a replica set.

Testing automated failover

To test how automated failover works if the current master is stopped, follow the steps below:

  1. Stop the current master instance (instance002) using the tt stop command:

    $ tt stop auto_leader:instance002
   • The Instance auto_leader:instance002 (PID = 24769) has been terminated.

  2. On instance001, check box.info.election. In this example, a new replica set leader is instance001.

    auto_leader:instance001> box.info.election
---
- leader_idle: 0
  leader_name: instance001
  state: leader
  vote: 2
  term: 3
  leader: 2
...

  3. Check replication status using box.info.replication for instance002:

    • upstream.status is disconnected.
    • downstream.status is stopped.
    auto_leader:instance001> box.info.replication
---
- 1:
    id: 1
    uuid: 4cfa6e3c-625e-b027-00a7-29b2f2182f23
    lsn: 32
    upstream:
      peer: replicator@127.0.0.1:3302
      lag: 0.00032305717468262
      status: disconnected
      idle: 48.352504000002
      message: 'connect, called on fd 20, aka 127.0.0.1:62575: Connection refused'
      system_message: Connection refused
    name: instance002
    downstream:
      status: stopped
      message: 'unexpected EOF when reading from socket, called on fd 32, aka 127.0.0.1:3301,
        peer of 127.0.0.1:62204: Broken pipe'
      system_message: Broken pipe
  2:
    id: 2
    uuid: 9bb111c2-3ff5-36a7-00f4-2b9a573ea660
    lsn: 1
    name: instance001
  3:
    id: 3
    uuid: 9a3a1b9b-8a18-baf6-00b3-a6e5e11fd8b6
    lsn: 0
    upstream:
      status: follow
      idle: 0.18620999999985
      peer: replicator@127.0.0.1:3303
      lag: 0.00012516975402832
    name: instance003
    downstream:
      status: follow
      idle: 0.19718099999955
      vclock: {2: 1, 1: 32}
      lag: 0.00051403045654297
...

    The diagram below illustrates how the upstream and downstream connections look like:

    replication status on a new master

  4. Start instance002 back using tt start:

    $ tt start auto_leader:instance002
   • Starting an instance [auto_leader:instance002]...

Choosing a leader manually

  1. Make sure that box.info.vclock values (except the 0 components) are the same on all instances:

    • instance001:

      auto_leader:instance001> box.info.vclock
---
- {0: 2, 1: 32, 2: 1}
...

    • instance002:

      auto_leader:instance002> box.info.vclock
---
- {0: 2, 1: 32, 2: 1}
...

    • instance003:

      auto_leader:instance003> box.info.vclock
---
- {0: 3, 1: 32, 2: 1}
...

  2. On instance002, run box.ctl.promote() to choose it as a new replica set leader:

    auto_leader:instance002> box.ctl.promote()
---
...

  3. Check box.info.election to make sure instance002 is a leader now:

    auto_leader:instance002> box.info.election
---
- leader_idle: 0
  leader_name: instance002
  state: leader
  vote: 1
  term: 4
  leader: 1
...

Adding and removing instances

The process of adding instances to a replica set and removing them is similar for all failover modes. Learn how to do this from the Master-replica: manual failover tutorial:

Before removing an instance from a replica set with replication.failover set to election, make sure this instance is in read-only mode. If the instance is a master, choose a new leader manually.

Master-master

Example on GitHub: master_master

This tutorial shows how to configure and work with a master-master replica set.

Prerequisites

Before starting this tutorial:

  1. Install the tt utility.

  2. Create a tt environment in the current directory by executing the tt init command.

  3. Inside the instances.enabled directory of the created tt environment, create the master_master directory.

  4. Inside instances.enabled/master_master, create the instances.yml and config.yaml files:

    • instances.yml specifies instances to run in the current environment and should look like this:

      instance001:
instance002:

    • The config.yaml file is intended to store a replica set configuration.

Configuring a replica set

This section describes how to configure a replica set in config.yaml.

Step 1: Configuring a failover mode

First, set the replication.failover option to off:

replication:
  failover: off

Step 2: Defining a replica set topology

Define a replica set topology inside the groups section:

  • The database.mode option should be set to rw to make instances work in read-write mode.
  • The iproto.listen option specifies an address used to listen for incoming requests and allows replicas to communicate with each other.
groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            database:
              mode: rw
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
          instance002:
            database:
              mode: rw
            iproto:
              listen:
              - uri: '127.0.0.1:3302'

Step 3: Creating a user for replication

In the credentials section, create the replicator user with the replication role:

credentials:
  users:
    replicator:
      password: 'topsecret'
      roles: [replication]

Step 4: Specifying advertise URIs

Set iproto.advertise.peer to advertise the current instance to other replica set members:

iproto:
  advertise:
    peer:
      login: replicator

Resulting configuration

The resulting replica set configuration should look as follows:

credentials:
  users:
    replicator:
      password: 'topsecret'
      roles: [replication]

iproto:
  advertise:
    peer:
      login: replicator

replication:
  failover: off

groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            database:
              mode: rw
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
          instance002:
            database:
              mode: rw
            iproto:
              listen:
              - uri: '127.0.0.1:3302'

Working with a replica set

Starting instances

  1. After configuring a replica set, execute the tt start command from the tt environment directory:

    $ tt start master_master
   • Starting an instance [master_master:instance001]...
   • Starting an instance [master_master:instance002]...

  2. Check that instances are in the RUNNING status using the tt status command:

    $ tt status master_master
INSTANCE                      STATUS      PID   MODE
master_master:instance001     RUNNING     30818 RW
master_master:instance002     RUNNING     30819 RW

Checking a replica set status

  1. Connect to both instances using tt connect. Below is the example for instance001:

    $ tt connect master_master:instance001
   • Connecting to the instance...
   • Connected to master_master:instance001

master_master:instance001>

  2. Check that both instances are writable using box.info.ro:

    • instance001:

      master_master:instance001> box.info.ro
---
- false
...

    • instance002:

      master_master:instance002> box.info.ro
---
- false
...

  3. Execute box.info.replication to check a replica set status. For instance002, upstream.status and downstream.status should be follow.

    master_master:instance001> box.info.replication
---
- 1:
    id: 1
    uuid: c3bfd89f-5a1c-4556-aa9f-461377713a2a
    lsn: 7
    name: instance001
  2:
    id: 2
    uuid: dccf7485-8bff-47f6-bfc4-b311701e36ef
    lsn: 0
    upstream:
      status: follow
      idle: 0.93246499999987
      peer: replicator@127.0.0.1:3302
      lag: 0.00016188621520996
    name: instance002
    downstream:
      status: follow
      idle: 0.8988360000003
      vclock: {1: 7}
      lag: 0
...

    To see the diagrams that illustrate how the upstream and downstream connections look, refer to Monitoring a replica set.

Примечание

Note that a vclock value might include the 0 component that is related to local space operations and might differ for different instances in a replica set.

Adding data

To check that both instances get updates from each other, follow the steps below:

  1. On instance001, create a space, format it, and create a primary index:

    box.schema.space.create('bands')
box.space.bands:format({
    { name = 'id', type = 'unsigned' },
    { name = 'band_name', type = 'string' },
    { name = 'year', type = 'unsigned' }
})
box.space.bands:create_index('primary', { parts = { 'id' } })

    Then, add sample data to this space:

    box.space.bands:insert { 1, 'Roxette', 1986 }
box.space.bands:insert { 2, 'Scorpions', 1965 }

  2. On instance002, use the select operation to make sure data is replicated:

    master_master:instance002> box.space.bands:select()
---
- - [1, 'Roxette', 1986]
  - [2, 'Scorpions', 1965]
...

  3. Add more data to the created space on instance002:

    box.space.bands:insert { 3, 'Ace of Base', 1987 }
box.space.bands:insert { 4, 'The Beatles', 1960 }

  4. Get back to instance001 and use select to make sure new records are replicated:

    master_master:instance001> box.space.bands:select()
---
- - [1, 'Roxette', 1986]
  - [2, 'Scorpions', 1965]
  - [3, 'Ace of Base', 1987]
  - [4, 'The Beatles', 1960]
...

  5. Check that box.info.vclock values are the same on both instances:

    • instance001:

      master_master:instance001> box.info.vclock
---
- {2: 2, 1: 12}
...

    • instance002:

      master_master:instance002> box.info.vclock
---
- {2: 2, 1: 12}
...

Resolving replication conflicts

Примечание

To learn how to fix and prevent replication conflicts using trigger functions, see Resolving replication conflicts.

Inserting conflicting records

To insert conflicting records to instance001 and instance002, follow the steps below:

  1. Stop instance001 using the tt stop command:

    $ tt stop master_master:instance001

  2. On instance002, insert a new record:

    box.space.bands:insert { 5, 'incorrect data', 0 }

  3. Stop instance002 using tt stop:

    $ tt stop master_master:instance002

  4. Start instance001 back:

    $ tt start master_master:instance001

  5. Connect to instance001 and insert a record that should conflict with a record already inserted on instance002:

    box.space.bands:insert { 5, 'Pink Floyd', 1965 }

  6. Start instance002 back:

    $ tt start master_master:instance002

    Then, check box.info.replication on instance001. upstream.status should be stopped because of the Duplicate key exists error:

    master_master:instance001> box.info.replication
---
- 1:
    id: 1
    uuid: c3bfd89f-5a1c-4556-aa9f-461377713a2a
    lsn: 13
    name: instance001
  2:
    id: 2
    uuid: dccf7485-8bff-47f6-bfc4-b311701e36ef
    lsn: 2
    upstream:
      peer: replicator@127.0.0.1:3302
      lag: 115.99977827072
      status: stopped
      idle: 2.0342070000006
      message: Duplicate key exists in unique index "primary" in space "bands" with
        old tuple - [5, "Pink Floyd", 1965] and new tuple - [5, "incorrect data",
        0]
    name: instance002
    downstream:
      status: stopped
      message: 'unexpected EOF when reading from socket, called on fd 24, aka 127.0.0.1:3301,
        peer of 127.0.0.1:58478: Broken pipe'
      system_message: Broken pipe
...

    The diagram below illustrates how the upstream and downstream connections look like:

    replication status on a new master

Reseeding a replica

To resolve a replication conflict, instance002 should get the correct data from instance001 first. To achieve this, instance002 should be rebootstrapped:

  1. Select all the tuples in the box.space._cluster system space to get a UUID of instance002:

    master_master:instance001> box.space._cluster:select()
---
- - [1, 'c3bfd89f-5a1c-4556-aa9f-461377713a2a', 'instance001']
  - [2, 'dccf7485-8bff-47f6-bfc4-b311701e36ef', 'instance002']
...

  2. In the config.yaml file, change the following instance002 settings:

    • Set database.mode to ro.
    • Set database.instance_uuid to a UUID value obtained in the previous step.
    instance002:
  database:
    mode: ro
    instance_uuid: 'dccf7485-8bff-47f6-bfc4-b311701e36ef'

  3. Reload configurations on both instances using the config:reload() function:

    • instance001:

      master_master:instance001> require('config'):reload()
---
...

    • instance002:

      master_master:instance002> require('config'):reload()
---
...

  4. Delete write-ahead logs and snapshots stored in the var/lib/instance002 directory.

    Примечание

    var/lib is the default directory used by tt to store write-ahead logs and snapshots. Learn more from Configuration.

  5. Restart instance002 using the tt restart command:

    $ tt restart master_master:instance002

  6. Connect to instance002 and make sure it received the correct data from instance001:

    master_master:instance002> box.space.bands:select()
---
- - [1, 'Roxette', 1986]
  - [2, 'Scorpions', 1965]
  - [3, 'Ace of Base', 1987]
  - [4, 'The Beatles', 1960]
  - [5, 'Pink Floyd', 1965]
...

Restarting replication

After reseeding a replica, you need to resolve a replication conflict that keeps replication stopped:

  1. Execute box.info.replication on instance001. upstream.status is still stopped:

    master_master:instance001> box.info.replication
---
- 1:
    id: 1
    uuid: c3bfd89f-5a1c-4556-aa9f-461377713a2a
    lsn: 13
    name: instance001
  2:
    id: 2
    uuid: dccf7485-8bff-47f6-bfc4-b311701e36ef
    lsn: 2
    upstream:
      peer: replicator@127.0.0.1:3302
      lag: 115.99977827072
      status: stopped
      idle: 1013.688243
      message: Duplicate key exists in unique index "primary" in space "bands" with
        old tuple - [5, "Pink Floyd", 1965] and new tuple - [5, "incorrect data",
        0]
    name: instance002
    downstream:
      status: follow
      idle: 0.69694700000036
      vclock: {2: 2, 1: 13}
      lag: 0
...

    The diagram below illustrates how the upstream and downstream connections look like:

    replication status after reseeding a replica

  2. In the config.yaml file, clear the iproto option for instance001 by setting its value to {} to disconnect this instance from instance002. Set database.mode to ro:

    instance001:
  database:
    mode: ro
  iproto: {}

  3. Reload configuration on instance001 only:

    master_master:instance001> require('config'):reload()
---
...

  4. Change database.mode values back to rw for both instances and restore iproto.listen for instance001. The database.instance_uuid option can be removed for instance002:

    instance001:
  database:
    mode: rw
  iproto:
    listen:
    - uri: '127.0.0.1:3301'
instance002:
  database:
    mode: rw
  iproto:
    listen:
    - uri: '127.0.0.1:3302'

  5. Reload configurations on both instances one more time:

    • instance001:

      master_master:instance001> require('config'):reload()
---
...

    • instance002:

      master_master:instance002> require('config'):reload()
---
...

  6. Check box.info.replication. upstream.status should be follow now.

    master_master:instance001> box.info.replication
---
- 1:
    id: 1
    uuid: c3bfd89f-5a1c-4556-aa9f-461377713a2a
    lsn: 13
    name: instance001
  2:
    id: 2
    uuid: dccf7485-8bff-47f6-bfc4-b311701e36ef
    lsn: 2
    upstream:
      status: follow
      idle: 0.86873800000012
      peer: replicator@127.0.0.1:3302
      lag: 0.0001060962677002
    name: instance002
    downstream:
      status: follow
      idle: 0.058662999999797
      vclock: {2: 2, 1: 13}
      lag: 0
...

Adding and removing instances

The process of adding instances to a replica set and removing them is similar for all failover modes. Learn how to do this from the Master-replica: manual failover tutorial:

Before removing an instance from a replica set with replication.failover set to off, make sure this instance is in read-only mode.

Sharding

С ростом проекта масштабируемость баз данных часто становится одной из наиболее серьезных проблем. Если отдельный сервер не может справиться с нагрузкой, необходимо применять средства масштабирования.

Шардирование – это архитектурый принцип баз данных, который позволяет их горизонтально масштабировать, что означает разбиение набора даных на части и распределение их по нескольким серверам.

С помощью модуля vshard кортежи набора данных распределяются по множеству узлов, на каждом из которых находится экземпляр сервера базы данных Tarantool. Каждый экземпляр обрабатывает лишь подмножество от общего количества данных, поэтому увеличение нагрузки можно компенсировать добавлением новых серверов. Первоначальный набор данных секционируется на множество частей, то есть каждая часть хранится на отдельном сервере.

Модуль vshard основан на концепции виртуальных сегментов: набор кортежей распределяется на большое количество абстрактных виртуальных узлов (виртуальных сегментов, или просто сегментов далее по тексту), а не на малое количество физических узлов.

Секционирование набора данных осуществляется с помощью сегментных ключей (идентификаторов сегментов). Хеширование сегментного ключа в большое количество сегментов позволяет незаметно для пользователя изменять количество серверов в кластере. Механизм балансирования распределяет сегменты между шардами при добавлении или удалении каких-либо серверов.

Для сегментов предусмотрены состояния, поэтому можно легко отслеживать состояние сервера. Например, активен ли экземпляр сервера и доступен ли он для всех типов запросов, или же произошел отказ, и сервер принимает только запросы на чтение.

Модуль vshard предоставляет общедоступные и внутренние API роутера и хранилища для приложений с поддержкой шардинга.

Начните с руководства по быстрому запуску или узнайте подробности об архитектуре шардирования в Tarantool:

Ознакомьтесь с руководством администратора по шардированию или перейдите к справочнику по конфигурации и API модуля vshard.

Архитектура

Общие сведения

Рассмотрим распределенный Tarantool-кластер, состоящий из подкластеров под названием шарды, в каждом из которых хранится некоторая часть данных. Каждый шард, в свою очередь, представляет собой набор реплик, одна из которых служит ведущим узлом, обрабатывающим все запросы на чтение и запись.

Весь набор данных при шардинге распределяется на заданное количество виртуальных сегментов (далее по тексту просто сегменты). Каждому из них присваивается уникальный номер от 1 до N, где N – это общее количество сегментов. Специально выбирается количество сегментов на несколько порядков больше, чем потенциальное количество кластерных узлов даже с учетом будущего масштабирования кластера. Например, если предполагается M узлов, набор данных может быть разделен на 100 * M или даже 1000 * M сегментов. Особое внимание следует уделить выбору количества сегментов: слишком большое число может потребовать дополнительную память для хранения информации о маршрутизации; слишком маленькое может привести к снижению степени детализации балансировки.

Каждый шард хранит уникальное подмножество сегментов. Один сегмент не может относиться к нескольким шардам одновременно, как показано на схеме ниже:

../../../_images/bucket.svg

Такая схема распределения сегментов по шардам хранится в таблице в одном из системных пространств Tarantool’а, при этом в каждом шарде содержится только определенную часть схемы, которая покрывает присвоенные этому шарду сегменты.

Помимо таблицы, идентификатор сегмента также хранится в специальном поле каждого кортежа каждой таблицы, участвующей в шардинге.

Как только шард получает любой запрос (за исключением SELECT) от приложения, этот шард сверяет идентификатор сегмента, указанный в запросе, с таблицей идентификаторов сегментов, которые принадлежат данному узлу. Если указанный идентификатор сегмента недействителен, то запрос завершается со следующей ошибкой: «wrong bucket” (неверный сегмент). В противном случае запрос выполняется, и всем создаваемым данным присваивается указанный в запросе идентификатор сегмента. Обратите внимание, что запрос должен изменять только данные с тем же идентификатором сегмента, что и в запросе.

Хранение идентификаторов сегментов как в самих данных, так и в таблице обеспечивает согласованность данных независимо от логики приложения и прозрачность балансировки для приложения. Хранение таблицы соответствий в системном спейсе обеспечивает последовательность шардинга в случае восстановления после отказа, так как у всех реплик в шарде будет одно исходное состояние таблицы.

Виртуальные сегменты

Набор данных при шардинге распределяется на большое количество абстрактных узлов, которые называются виртуальные сегменты (далее по тексту просто сегменты).

Секционирование набора данных происходит с помощью сегментного ключа (или идентификатора сегмента (bucket id) в терминах Tarantool). Идентификатор сегмента – это число от 1 до N, где N – это общее количество сегментов.

../../../_images/buckets.svg

В каждом наборе реплик есть уникальное подмножество сегментов. Один сегмент не может относиться к нескольким наборам реплик одновременно.

The total number of buckets is determined by the administrator who sets up the initial cluster configuration.

Every space you plan to shard must have a numeric field containing bucket id-s. You can learn more from Data definition.

Структура

Сегментированный кластер в Tarantool состоит из:

../../../_images/schema.svg

Хранилище

Хранилище (storage) – это узел, который хранит подмножество набора данных. Несколько реплицируемых (для резерва) хранилищ составляют набор реплик (также называемый шардом).

У каждого хранилища в наборе реплик есть роль: мастер или реплика. Мастер обрабатывает запросы на чтение и запись. Реплика обрабатывает запросы на чтение, но не может обрабатывать запросы на запись.

../../../_images/master_replica.svg

Роутер

Роутер (router) – это автономный компонент ПО, который обеспечивает маршрутизацию запросов чтения и записи от клиентского приложения к шардам.

Все запросы из приложения приходят в сегментированный кластер через роутер (router). Роутер сохраняет топологию сегментированного кластера прозрачной для приложения, не сообщая приложению:

  • номер и местоположение шардов,
  • процесс балансировки данных,
  • наличие отказа и восстановление после отказа реплики.

Роутер также может самостоятельно вычислить идентификатор сегмента при условии, что приложение четко определяет правила вычисления идентификатора сегмента на основе данных запроса. Для этого роутеру необходимо знать схему данных.

У роутера нет постоянного статуса, он не хранит топологию кластера и не выполняет балансировку данных. Роутер – это автономный компонент ПО, который может работать на уровне хранилища или на уровне приложения в зависимости от функций приложения.

Роутер поддерживает постоянный пул соединений со всеми хранилищами, созданными при запуске, что помогает избежать ошибок конфигурации. После создания пула роутер кэширует текущее состояние таблицы _vbucket, чтобы ускорить маршрутизацию. Если сегмент был перемещен в другое хранилище в результате балансировки, или же один из шардов переключается на реплику, роутер обновит таблицу маршрутизации так, чтобы это было понятно приложению.

Шардинг не интегрирован ни в одну систему централизованного хранения конфигураций. Предполагается, что само приложение обрабатывает взаимодействие с такой системой и передает параметры шардинга. При этом конфигурацию можно изменить динамически, например, при добавлении или удалении одного или нескольких шардов:

  1. Чтобы добавить новый шард в кластер, системный администратор сначала изменяет конфигурацию всех роутеров, а затем конфигурацию всех хранилищ.
  2. Новый шард становится доступен для балансировки на уровне хранилища.
  3. В результате балансировки один из виртуальных сегментов перемещается на новый шард.
  4. При попытке доступа к виртуальному сегменту роутер получает специальный код ошибки, который указывает новое местоположение сегмента.

CRUD-операции: create, read, update, delete (создание, чтение, изменение, удаление)

CRUD-операции могут:

  • либо выполняться в рамках хранимой процедуры в хранилище,
  • либо запускаться приложением.

В любом случае приложение должно включать идентификатор рабочего сегмента в запрос. При выполнении запроса вставки INSERT идентификатор сегмента хранится в созданном кортеже. В других случаях проверяется, совпадает ли указанный идентификатор рабочего сегмента с идентификатором сегмента кортежа, в который вносятся изменения.

SELECT-запросы

Поскольку хранилище не знает о соответствии идентификатора сегмента и первичного ключа, все запросы выборки SELECT в хранимых процедурах внутри хранилища выполняются только локально. SELECT-запросы, которые были инициализированы приложением, направляются на роутер. И если приложение передало идентификатор сегмента, роутер использует его для вычисления шарда.

Вызов хранимых процедур

Существует несколько способов вызвать хранимые процедуры в наборах реплик кластера. Хранимые процедуры можно вызвать:

  • либо на определенном виртуальном сегменте, расположенном в наборе реплик (в этом случае необходимо различать процедуры чтения и записи, так как процедуры записи не применимы к перемещаемым сегментам),
  • либо без указания определенного сегмента.

Все проверки правильности маршрутизации, выполняемые для шардированных DML-операций, распространяются и на хранимые процедуры, связанные с сегментами.

Балансировщик

Балансировщик представляет собой фоновый процесс балансировки, который обеспечивает равномерное распределение сегментов по шардам. Во время балансировки происходит миграция сегментов по наборам реплик.

The rebalancer «wakes up» periodically and redistributes data from the most loaded nodes to less loaded nodes. Rebalancing starts if the replicaset disbalance of a replica set exceeds a disbalance threshold specified in the configuration.

The replicaset disbalance is calculated as follows:

|эталонное_число_сегментов - текущее_число_сегментов| / эталонное_число_сегментов * 100

Миграция сегментов

Набор реплик, из которого переносится сегмент, называется исходный (source); а набор реплик, куда переносится сегмент, называется целевой (destination).

Блокировка набора реплик позволяет набору реплик оставаться невидимым для балансировщика. Набор реплик с блокировкой не может ни принимать новые сегменты, ни мигрировать свои собственные.

Во время миграции у сегмента могут быть разные статусы:

Сегменты в статусе мусора GARBAGE удаляются сборщиком мусора.

../../../_images/states.svg

Миграция происходит следующим образом:

  1. В целевом наборе реплик создается новый сегмент, который получает статус RECEIVING (принимающий), начинается копирование данных, и сегмент отклоняет все запросы.
  2. Отправляемый сегмент в исходном наборе реплик получает статус SENDING и продолжает обрабатывать запросы на чтение.
  3. После копирования данных сегмент в исходном наборе реплик получает статус отправленного (SENT) и перестает принимать запросы.
  4. Сегмент в целевом наборе реплик переходит в активный статус (ACTIVE) и начинает принимать все запросы.

Примечание

Есть специальная ошибка vshard.error.code.TRANSFER_IS_IN_PROGRESS, которая возвращается в том случае, если запрос пытается выполнить действие, неприменимое к перемещаемому сегменту. В этом случае необходимо повторить попытку выполнения запроса.

Системный спейс _bucket

Системный спейс _bucket в каждом наборе реплик хранит идентификаторы сегментов данного набора реплик. Спейс содержит следующие поля:

  • bucket – идентификатор сегмента
  • status – статус сегмента
  • destination – UUID целевого набора реплик

Пример _bucket.select{}:

---
- - [1, ACTIVE, abfe2ef6-9d11-4756-b668-7f5bc5108e2a]
  - [2, SENT, 19f83dcb-9a01-45bc-a0cf-b0c5060ff82c]
...

После миграции сегмента UUID целевого набора реплик вносится в таблицу. Пока сегмент еще находится в исходном наборе реплик, значение UUID целевого набора реплик равно NULL.

Таблица маршрутизации

Таблица маршрутизации роутера отображает все идентификаторы сегментов с соответствующими наборами реплик. Она обеспечивает консистентность шардинга в случае отказа.

Роутер поддерживает постоянный пул соединений со всеми хранилищами, созданными при запуске, что помогает избежать ошибки конфигурации. После создания пула соединений роутер кэширует текущее состояние таблицы маршрутизации, чтобы ускорить ее. Если произошла миграция сегмента в другое хранилище после балансировки или же отказ, который вызвал переключение шарда на другую реплику, файбер обнаружения (discovery fiber) в роутере обновит таблицу маршрутизации автоматически.

Поскольку идентификатор сегмента явно указан как в данных, так и в таблице отображения на роутере, данные сохраняются независимо от логики приложения. Это также обеспечивает прозрачность балансировки для приложения.

Обработка запросов

Запросы в базу данных можно производить из приложения или с помощью хранимых процедур. В любом случае идентификатор сегмента следует явным образом указать в запросе.

Сначала все запросы направляются в роутер. Роутер поддерживает только операцию вызова, которая выполняется с помощью функции vshard.router.call():

result = vshard.router.call(<идентификатор_сегмента>, <режим>, <имя_функции>, {<список_аргументов>}, {<опции>})

Запросы обрабатываются следующим образом:

  1. Роутер использует идентификатор сегмента для поиска набора реплик с соответствующим сегментом в таблице маршрутизации.

    Если роутер не содержит информацию о соответствии идентификатора сегмента набору реплик (файбер обнаружения еще не заполнил таблицу), роутер выполняет запросы ко всем хранилищам, чтобы обнаружить местонахождение сегмента.

  2. После обнаружения сегмента шард проверяет:

    • хранится ли сегмент в системном спейсе _bucket набора реплик;
    • находится ли сегмент в статусе ACTIVE (активный) или PINNED (закрепленный) (если выполняется запрос на чтение, то сегмент может находиться в состоянии отправки SENDING).

  3. Если проверка пройдена, запрос выполняется. В противном случае, выполнение запроса прекращается с ошибкой: “wrong bucket” (несоответствующий сегмент).

Глоссарий

Вертикальное масштабирование
Добавление мощности в отдельный сервер: использование более мощного процессора, добавление оперативной памяти, добавление хранилищ и т.д.
Горизонтальное масштабирование
Добавление дополнительных серверов в пул ресурсов, последующее секционирование и распределение набора данных по серверам.
Шардинг
Архитектура базы данных, которая допускает секционирование набора данных по сегментному ключу и распределение набора данных по нескольким серверам. Шардинг представляет собой частный случай горизонтального масштабирования.
Узел
Виртуальный или физический экземпляр сервера.
Кластер
Набор узлов, которые составляют отдельную группу.
Хранилище
Узел, который хранит подмножество данных из набора.
Набор реплик
Ряд узлов, на которых хранятся копии набора данных. У каждого хранилища в наборе реплик есть роль: мастер или реплика.
Мастер
Хранилище в наборе реплик, которое обрабатывает запросы на чтение и запись.
Реплика
Хранилище в наборе реплик, которое обрабатывает только запросы на чтение.
Запросы на чтение
Запросы только на чтение, то есть выборка.
Запросы на запись
Операции по изменению данных, то есть запросы на создание, чтение, изменение и удаление данных.
Сегменты (виртуальные сегменты)
Абстрактные виртуальные узлы, на которые производится секционирование набора данных по сегментному ключу (идентификатору сегмента).
Идентификатор сегмента
Сегментный ключ, который определяет принадлежность сегмента к определенному набору реплик. Идентификатор сегмента можно вычислить по хеш-ключу.
Роутер
Прокси-сервер, который отвечает за запросы маршрутизации от приложения к узлам в кластере.

Шардирование с vshard

Sharding in Tarantool is implemented in the vshard module. For a quick start with vshard, refer to Creating a sharded cluster.

Примечание

Starting with the 3.0 version, the recommended way of configuring Tarantool is using a configuration file. The sharding section defines configuration parameters related to sharding. To learn how to configure vshard in code, see Справочник по настройке.

Установка

Модуль vshard не входит в основной дистрибутив Tarantool. Чтобы установить модуль, выполните команду:

$ tt rocks install vshard

If you are developing a sharded cluster application, add the vshard module dependency to a *.rockspec file:

dependencies = {
    'vshard == 0.1.27'
}

Примечание

The minimum required version of vshard is 0.1.25.

Configuration overview

Configuring settings related to sharding might include the following steps:

  1. Configure connection settings to allow instances within a sharded cluster to communicate with each other.
  2. Specify which role each replica set plays in a sharded cluster.
  3. Configure how data is partitioned across shards.
  4. Specify settings related to data rebalancing.

Connectivity

This section describes connection options that enable communication between instances within a sharded cluster. For general information about connections, see the Connections topic.

Credentials

To allow a router and rebalancer to connect to storages, a user with the sharding role should be used. The example below shows how to grant the sharding role to the storage user:

credentials:
  users:
    replicator:
      password: 'topsecret'
      roles: [replication]
    storage:
      password: 'secret'
      roles: [sharding]

The sharding role has different privileges depending on a replica set’s sharding role. For replica sets with the storage sharding role, the sharding credential role has the following privileges:

  • All privileges provided by the replication role.
  • Executing vshard.storage.* functions.

If a replica set does not have the storage sharding role, the sharding credential role does not have any privileges.

Sharding roles

Each replica set in a sharded cluster can have one of three roles:

You can use the sharding.roles option to assign a specific role to a replica set or group of replica sets. In the example below, all replica sets in the storages group have the storage role while replica sets in the routers group have the router role.

groups:
  storages:
    sharding:
      roles: [storage]
    # ...
  routers:
    sharding:
      roles: [router]
    # ...

Note that the rebalancer role is optional. If it is not specified, a rebalancer is selected automatically from the master instances of replica sets. To specify the rebalancer manually or turn it off, use the sharding.rebalancer_mode option.

Data partitioning

This section describes configuration settings related to data partitioning. Learn how to define spaces to be sharded in Data definition.

Bucket count

To define the total number of buckets in a cluster, configure the sharding.bucket_count option at the global level. In the example below, sharding.bucket_count is set to 1000:

sharding:
  bucket_count: 1000

sharding.bucket_count should be several orders of magnitude larger than the potential number of cluster nodes considering potential scaling out in the future.

If the estimated number of nodes in a cluster is N, then the data set should be divided into 100N or even 1000N buckets depending on the planned scaling out. This number is greater than the potential number of cluster nodes in the system being designed.

Keep in mind that too many buckets can cause a need to allocate more memory to store routing information. On the other hand, an insufficient number of buckets can lead to decreased granularity when rebalancing.

Вес набора реплик

A replica set weight defines the storage capacity of the replica set: the larger the weight, the more buckets the replica set can store. You can configure a replica set weight using the sharding.weight option. This option can be used to store the prevailing amount of data on a replica set with more memory space. You can also assign a zero weight to a replica set to initiate migration of its buckets to the remaining cluster nodes.

In the example below, the storage-a replica set can store twice as much data as storage-b:

# ...
replicasets:
  storage-a:
    sharding:
      weight: 2
    # ...
  storage-b:
    sharding:
      weight: 1
    # ...

Data rebalancing

Процесс балансировки

Существует эталонное число сегментов в наборе реплик («эталонный» в данном случае значит идеальный). Если во всем наборе реплик это число остается неизменным, то сегменты распределяются равномерно.

The etalon number is calculated automatically considering the number of buckets in the cluster and the weights of the replica sets.

Rebalancing starts if the disbalance threshold of a replica set exceeds the disbalance threshold specified in the configuration (the sharding.rebalancer_disbalance_threshold option).

Предел дисбаланса набора реплик рассчитывается следующим образом:

|эталонное_число_сегментов - текущее_число_сегментов| / эталонное_число_сегментов * 100

For example, a cluster is configured as follows:

In this case, the etalon numbers of buckets for the replica sets are:

  • 1st replica set – 1000.
  • 2nd replica set – 500.
  • 3rd replica set – 1500.

You can set a replica set weight to zero to initiate migration of its buckets to the remaining cluster nodes. You can also add a new replica set with a non-zero weight to initiate migration of the buckets from the existing replica sets.

When a new shard is added, a configuration should be reloaded on each instance to migrate buckets to a new shard:

  • If a centralized configuration storage is used, Tarantool reloads a changed configuration automatically.
  • If a local configuration file is used, you need to reload a configuration on all the routers first and then on all the storages.

Параллельная балансировка

Originally, vshard had quite a simple rebalancer – one process on one node that calculated routes that should send buckets, how many, and to whom. The nodes applied these routes one by one sequentially.

К сожалению, такая простая схема работала недостаточно быстро, особенно для Vinyl’а, где затраты ресурсов на чтение диска были сопоставимы с сетевыми затратами. На самом деле, механизм применения маршрутов в балансировщике Vinyl’а большую часть времени был в режиме ожидания.

Теперь каждый узел может параллельно посылать несколько сегментов по кругу в несколько пунктов назначения или всего в один.

To set the degree of parallelism, use the sharding.rebalancer_max_sending option:

sharding:
  rebalancer_max_sending: 5

Примечание

Specifying sharding.rebalancer_max_sending = N probably won’t give N times speed up. It depends on network, disk, number of other fibers in the system.

Example 1

У вас уже есть 10 наборов реплик, добавили новый. Теперь все 10 наборов реплик будут пытаться отправить сегменты на новый.

Assume that each replica set can send up to 5 buckets at once. In that case, the new replica set will experience a rather big load of 50 buckets being downloaded at once. If the node needs to do some other work, perhaps such a big load is undesirable. Also too, many parallel buckets can cause timeouts in the rebalancing process itself.

To fix the problem, you can set a lower value for rebalancer_max_sending for old replica sets, or decrease rebalancer_max_receiving for the new one. In the latter case, some workers on old nodes will be throttled, and you will see that in the logs.

rebalancer_max_sending is important, if you have restrictions for the maximum number of buckets that can be read only at once in the cluster. As you remember, when a bucket is being sent, it does not accept new write requests.

Example 2

У вас есть 100 000 сегментов, и каждый сегмент хранит ~ 0,001% ваших данных. В кластере 10 наборов реплик. И нельзя позволить себе заблокировать для записи > 0,1% данных. Таким образом, не следует устанавливать значение rebalancer_max_sending > 10 на этих узлах. Тогда балансировщик не будет посылать более 100 сегментов одновременно по всему кластеру.

If rebalancer_max_sending is too high and rebalancer_max_receiving is too low, then some buckets will try to get relocated – and will fail with that. This problem will consume network resources and time. It is important to configure these parameters to not conflict with each other.

Блокировка набора реплик и закрепление корзины

A replica set lock (sharding.lock) makes a replica set invisible to the rebalancer: a locked replica set can neither receive new buckets nor migrate its own buckets.

A bucket pin (vshard.storage.bucket_pin(bucket_id)) blocks a specific bucket from migrating: a pinned bucket stays on the replica set to which it is pinned until it is unpinned.

Закрепление всех сегментов в наборе реплик не означает блокирование набора реплик. Даже после закрепления всех сегментов незаблокированный набор реплик может принимать новые сегменты.

A replica set lock is helpful, for example, to separate a replica set from production replica sets for testing, or to preserve some application metadata that must not be sharded for a while. A bucket pin is used for similar cases but in a smaller scope.

By both locking a replica set and pinning all buckets, you can isolate an entire replica set.

Заблокированные наборы реплик и закрепленные сегменты влияют на алгоритм балансировки, так как балансировщик должен игнорировать заблокированные наборы реплик и учитывать закрепленные сегменты при попытке достичь наилучшего возможного баланса.

Это нетривиальная задача, поскольку пользователь может закрепить слишком много сегментов в наборе реплик, так что становится невозможным достижение идеального баланса. Например, рассмотрим следующий кластер (предположим, что все веса наборов реплик равны 1).

Начальная конфигурация:

rs1: bucket_count = 150 -- число сегментов
rs2: bucket_count = 150, pinned_count = 120 -- число сегментов, число закрепленных сегментов

Добавление нового набора реплик:

rs1: bucket_count = 150
rs2: bucket_count = 150, pinned_count = 120
rs3: bucket_count = 0

Идеальным балансом было бы 100 - 100 - 100, чего невозможно достичь, поскольку набор реплик rs2 содержит 120 закрепленных сегментов. The best possible balance here is the following:

rs1: bucket_count = 90
rs2: bucket_count = 120, pinned_count 120
rs3: bucket_count = 90

The rebalancer moved as many buckets as possible from rs2 to decrease the disbalance. At the same time, it respected equal weights of rs1 and rs3.

Алгоритмы реализации блокировки и закрепления совершенно разные, хотя с точки зрения функций они похожи.

Заблокированный набор реплик и балансировка

Locked replica sets do not participate in rebalancing. This means that even if the actual total number of buckets is not equal to the etalon number, the disbalance cannot be fixed due to the lock. When the rebalancer detects that one of the replica sets is locked, it recalculates the etalon number of buckets of the non-locked replica sets as if the locked replica set and its buckets did not exist at all.

Закрепленный набор реплик и балансировка

Балансировка наборов реплик с закрепленными сегментами требует более сложного алгоритма. Здесь pinned_count[o] – это число закрепленных сегментов, а etalon_count – это эталонное число сегментов для набора реплик:

  1. Балансировщик рассчитывает эталонное число сегментов, как если бы все сегменты не были закреплены. Затем балансировщик проверяет каждый набор реплик и сопоставляет эталонное число сегментов с числом закрепленных сегментов в наборе реплик. Если pinned_count < etalon_count, незаблокированные наборы реплик (на данном этапе все заблокированные наборы реплик уже отфильтрованы) с закрепленными сегментами могут получать новые сегменты.
  2. Если же pinned_count > etalon_count, дисбаланс исправить нельзя, так как балансировщик не может вывести закрепленные сегменты из этого набора реплик. В таком случае эталонное число обновляется как равное числу закрепленных сегментов. Наборы реплик с pinned_count > etalon_count не обрабатываются балансировщиком`, а число закрепленных сегментов вычитается из общего числа сегментов. Балансировщик пытается вывести как можно больше сегментов из таких наборов реплик.
  3. Эта процедура перезапускается с шага 1 для наборов реплик с pinned_count >= etalon_count до тех пор, пока не будет выполнено условие pinned_count <= etalon_count для всех наборов реплик. Процедура также перезапускается при изменении общего числа сегментов.

Псевдокод для данного алгоритма будет следующим:

function cluster_calculate_perfect_balance(replicasets, bucket_count)
        -- балансировка сегментов с использованием веса рабочих наборов реплик --
end;

cluster = <all of the non-locked replica sets>;
bucket_count = <the total number of buckets in the cluster>;
can_reach_balance = false
while not can_reach_balance do
        can_reach_balance = true
        cluster_calculate_perfect_balance(cluster, bucket_count);
        foreach replicaset in cluster do
                if replicaset.perfect_bucket_count <
                   replicaset.pinned_bucket_count then
                        can_reach_balance = false
                        bucket_count -= replicaset.pinned_bucket_count;
                        replicaset.perfect_bucket_count =
                                replicaset.pinned_bucket_count;
                end;
        end;
end;
cluster_calculate_perfect_balance(cluster, bucket_count);

Сложность алгоритма составляет O(N^2), где N – количество наборов реплик. На каждом шаге алгоритм либо завершает вычисление, либо игнорирует хотя бы один новый набор реплик, перегруженный закрепленными сегментами, и обновляет эталонное число сегментов в других наборах реплик.

Ссылка в сегменте

Ссылка в сегменте – это счетчик в оперативной памяти, который похож на закрепление сегмента со следующими отличиями:

  1. Ссылка в сегменте никогда не сохраняется. Ссылки предназначены для запрета передачи сегментов во время выполнения запроса, но при перезапуске все запросы отбрасываются.

  2. Есть 2 типа ссылок в сегменте: только чтение (RO) и чтение-запись (RW).

    Если в сегменте есть ссылки типа RW, его нельзя перемещать. Однако, если балансировщику требуется отправка этого сегмента, он блокирует его для новых запросов на запись, ожидает завершения всех текущих запросов, а затем отправляет сегмент.

    Если в сегменте есть ссылки типа RO, его можно отправить, но нельзя удалить. Такой сегмент может даже перейти в статус мусора GARBAGE или отправки SENT, но его данные сохраняются до тех пор, пока не уйдет последний читатель.

    В одном сегменте могут быть ссылки как типа RO, так и типа RW.

  3. Ссылки в сегменте исчисляются.

The vshard.storage.bucket_ref/unref() methods are called automatically when vshard.router.call() or vshard.storage.call() is used. For raw API like r = vshard.router.route() r:callro/callrw, you should explicitly call the bucket_ref() method inside the function. Also, make sure that you call bucket_unref() after bucket_ref(), otherwise the bucket cannot be moved from the storage until the instance is restarted.

Чтобы узнать количество ссылок в сегменте, используйте vshard.storage.buckets_info([идентификатор_сегмента]) (параметр идентификатор_сегмента необязателен).

Пример:

vshard.storage.buckets_info(1)
---
- 1:
    status: active
    ref_rw: 1
    ref_ro: 1
    ro_lock: true
    rw_lock: true
    id: 1

Defining and manipulating data

Data definition

Sharded spaces should be defined in a storage application inside box.once() and should have a field with bucket id values. This field should meet the following requirements:

  • The field’s data type can be unsigned, number, or integer.
  • The field must be non-nullable.
  • The field must be indexed by the shard_index. The default name for this index is bucket_id.

In the example below, the bands space has the bucket_id field, which is used to partition a dataset across different storage instances:

box.once('bands', function()
    box.schema.create_space('bands', {
        format = {
            { name = 'id', type = 'unsigned' },
            { name = 'bucket_id', type = 'unsigned' },
            { name = 'band_name', type = 'string' },
            { name = 'year', type = 'unsigned' }
        },
        if_not_exists = true
    })
    box.space.bands:create_index('id', { parts = { 'id' }, if_not_exists = true })
    box.space.bands:create_index('bucket_id', { parts = { 'bucket_id' }, unique = false, if_not_exists = true })
end)

Example on GitHub: sharded_cluster

Data manipulation

All DML operations with data should be performed via a router using the vshard.router.call functions, such as vshard.router.callrw() or vshard.router.callro(). For example, a storage application has the insert_band function used to insert new tuples:

function insert_band(id, bucket_id, band_name, year)
    box.space.bands:insert({ id, bucket_id, band_name, year })
end

In a router application, you can define the put function that specifies how a router selects the storage to write data:

function put(id, band_name, year)
    local bucket_id = vshard.router.bucket_id_mpcrc32({ id })
    vshard.router.callrw(bucket_id, 'insert_band', { id, bucket_id, band_name, year })
end

Learn more at Обработка запросов.

Sharded cluster maintenance

Master crash

В случае отказа мастера в наборе реплик рекомендуется:

  1. Переключить одну из реплик в режим мастера, что позволит новому мастеру обрабатывать все входящие запросы.
  2. Обновить конфигурацию всех членов кластера, в результате чего все запросы будут перенаправлены на новый мастер.

Replica set crash

In case a whole replica set fails, some part of the dataset becomes inaccessible. Meanwhile, the router tries to reconnect to the master of the failed replica set. This way, once the replica set is up and running again, the cluster is automatically restored.

Master scheduled downtime

Для проведения запланированного остановки мастера в наборе реплик рекомендуется:

  1. Update the configuration to use another instance as a master.
  2. Reload the configuration on all the instances. All the requests then are forwarded to a new master.
  3. Отключить старый мастер.

Replica set scheduled downtime

Для проведения запланированной остановки набора реплик рекомендуется:

  1. Migrate all the buckets to the other cluster storages. You can do this by assigning a zero weight to a replica set to initiate migration of its buckets to the remaining cluster nodes.
  2. Обновить конфигурацию всех узлов.
  3. Отключить набор реплик.

Файберы

Поиск сегментов, восстановление сегментов и балансировка сегментов выполняются автоматически и не требуют ручного вмешательства.

С технической точки зрения есть несколько файберов, которые отвечают за различные типы действий:

Для получения подробной информации см. разделы Процесс балансировки и Миграция сегментов.

Сборщик мусора

Файбер сборщик мусора работает в фоновом режиме на мастер-хранилищах в каждом наборе реплик. Он начинает удалять содержимое сегмента в состоянии мусора GARBAGE по частям. Когда сегмент пуст, запись о нем удаляется из системного спейса _bucket.

Восстановление сегмента

Файбер восстановления сегмента работает на мастер-хранилищах. Он помогает восстановить сегменты в статусах отправки SENDING и получения RECEIVING в случае перезагрузки.

Сегменты в статусе SENDING восстанавливаются следующим образом:

  1. Сначала система ищет сегменты в статусе SENDING.
  2. Если такой сегмент обнаружен, система отправляет запрос в целевой набор реплик.
  3. Если сегмент в целевом наборе реплик находится в активном статусе ACTIVE, исходный сегмент удаляется из исходного узла.

Сегменты в статусе RECEIVING удаляются без дополнительных проверок.

Восстановление после отказа

A failover fiber runs on every router. If a master of a replica set becomes unavailable, the failover fiber redirects read requests to the replicas. Write requests are rejected with an error until the master becomes available.

Connections and authentication

This section contains guides on how to configure connections and authentication features.

Connections

To set up a Tarantool cluster, you need to enable communication between its instances, regardless of whether they running on one or different hosts. This requires configuring connection settings that include:

Configuring connection settings is also required to enable communication of a Tarantool cluster to external systems. For example, this might be administering cluster members using tt, managing clusters using Tarantool Cluster Manager, or using connectors for different languages.

This topic describes how to define connection settings in the iproto section of a YAML configuration.

Примечание

iproto is a binary protocol used to communicate between cluster instances and with external systems.

Listen URI

To configure URIs used to listen for incoming requests, use the iproto.listen configuration option.

One listen address

The example below shows how to set a listening IP address for instance001 to 127.0.0.1:3301:

instance001:
  iproto:
    listen:
    - uri: '127.0.0.1:3301'

Multiple listen addresses

In this example, instance001 listens on two IP addresses:

instance001:
  iproto:
    listen:
    - uri: '127.0.0.1:3301'
    - uri: '127.0.0.1:3302'

Listen port

You can pass only a port value to iproto.listen:

instance001:
  iproto:
    listen:
    - uri: '3301'

In this case, this port is used for all IP addresses the server listens on.

SSL parameters

In the Enterprise Edition, you can enable SSL for a connection using the params section of the specified URI:

instance001:
  iproto:
    listen:
    - uri: '127.0.0.1:3301'
      params:
        transport: 'ssl'
        ssl_cert_file: 'certs/server.crt'
        ssl_key_file: 'certs/server.key'

Learn more from Securing connections with SSL.

Unix domain socket

For local development, you can enable communication between cluster members by using Unix domain sockets:

instance001:
  iproto:
    listen:
    - uri: 'unix/:./var/run/{{ instance_name }}/tarantool.iproto'

Securing connections with SSL

Enterprise Edition

SSL is supported by the Enterprise Edition only.

Tarantool supports the use of SSL connections to encrypt client-server communications for increased security. To enable SSL, use the <uri>.params.* options, which can be applied to both listen and advertise URIs.

Without CA

The example below demonstrates how to enable traffic encryption by using a self-signed server certificate. The following parameters are specified for each instance:

instances:
  instance001:
    iproto:
      listen:
      - uri: '127.0.0.1:3301'
        params:
          transport: 'ssl'
          ssl_cert_file: 'certs/server.crt'
          ssl_key_file: 'certs/server.key'
  instance002:
    iproto:
      listen:
      - uri: '127.0.0.1:3302'
        params:
          transport: 'ssl'
          ssl_cert_file: 'certs/server.crt'
          ssl_key_file: 'certs/server.key'
  instance003:
    iproto:
      listen:
      - uri: '127.0.0.1:3303'
        params:
          transport: 'ssl'
          ssl_cert_file: 'certs/server.crt'
          ssl_key_file: 'certs/server.key'

You can find the full example here: ssl_without_ca.

With CA

The example below demonstrates how to enable traffic encryption by using a server certificate signed by a trusted certificate authority. In this case, all replica set peers verify each other for authenticity.

The following parameters are specified for each instance:

  • ssl_ca_file: a path to a trusted certificate authorities (CA) file.
  • ssl_cert_file: a path to an SSL certificate file.
  • ssl_key_file: a path to a private SSL key file.
  • ssl_password (instance001): a password for an encrypted private SSL key.
  • ssl_password_file (instance002 and instance003): a text file containing passwords for encrypted SSL keys.
  • ssl_ciphers: a colon-separated list of SSL cipher suites the connection can use.
instances:
  instance001:
    iproto:
      listen:
      - uri: '127.0.0.1:3301'
        params:
          transport: 'ssl'
          ssl_ca_file: 'certs/root_ca.crt'
          ssl_cert_file: 'certs/instance001/server001.crt'
          ssl_key_file: 'certs/instance001/server001.key'
          ssl_password: 'qwerty'
          ssl_ciphers: 'ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256'
  instance002:
    iproto:
      listen:
      - uri: '127.0.0.1:3302'
        params:
          transport: 'ssl'
          ssl_ca_file: 'certs/root_ca.crt'
          ssl_cert_file: 'certs/instance002/server002.crt'
          ssl_key_file: 'certs/instance002/server002.key'
          ssl_password_file: 'certs/ssl_passwords.txt'
          ssl_ciphers: 'ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256'
  instance003:
    iproto:
      listen:
      - uri: '127.0.0.1:3303'
        params:
          transport: 'ssl'
          ssl_ca_file: 'certs/root_ca.crt'
          ssl_cert_file: 'certs/instance003/server003.crt'
          ssl_key_file: 'certs/instance003/server003.key'
          ssl_password_file: 'certs/ssl_passwords.txt'
          ssl_ciphers: 'ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256'

You can find the full example here: ssl_with_ca.

Reloading certificates

To reload SSL certificate files specified in the configuration, open an admin console and reload the configuration using config.reload():

require('config'):reload()

New certificates will be used for new connections. Existing connections will continue using old SSL certificates until reconnection is required. For example, certificate expiry or a network issue causes reconnection.

Credentials

Tarantool enables flexible management of access to various database resources by providing specific privileges to users. You can read more about the main concepts of Tarantool access control system in the Управление доступом section.

This topic describes how to create users and grant them the specified privileges in the credentials section of a YAML configuration. For example, you can define users with the replication and sharding roles to maintain replication and sharding in a Tarantool cluster.

Managing users and roles

Creating a user

You can create new or configure credentials of the existing users in the credentials.users section.

In the example below, a dbadmin user without a password is created:

credentials:
  users:
    dbadmin: {}

To set a password, use the credentials.users.<username>.password option:

credentials:
  users:
    dbadmin:
      password: 'T0p_Secret_P@$$w0rd'

Granting privileges to a user

To assign a role to a user, use the credentials.users.<username>.roles option. In this example, the dbadmin user gets privileges granted to the super built-in role:

credentials:
  users:
    dbadmin:
      password: 'T0p_Secret_P@$$w0rd'
      roles: [ super ]

To create a new role, define it in the credentials.roles.* section. In the example below, the writers_space_reader role gets privileges to select data in the writers space:

roles:
  writers_space_reader:
    privileges:
    - permissions: [ read ]
      spaces: [ writers ]

Then, you can assign this role to a user using credentials.users.<username>.roles (sampleuser in the example below):

sampleuser:
  password: '123456'
  roles: [ writers_space_reader ]

You can grant specific privileges directly using credentials.users.<username>.privileges. In this example, sampleuser gets privileges to select and modify data in the books space:

sampleuser:
  password: '123456'
  roles: [ writers_space_reader ]
  privileges:
  - permissions: [ read, write ]
    spaces: [ books ]

You can find the full example here: credentials.

Loading secrets from safe storage

Tarantool enables you to load secrets from safe storage such as external files or environment variables. To do this, you need to define corresponding options in the config.context section. In the examples below, context.dbadmin_password and context.sampleuser_password define how to load user passwords from *.txt files or environment variables:

After configuring how to load passwords, you can set password values using credentials.users.<username>.password as follows:

credentials:
  users:
    dbadmin:
      password: '{{ context.dbadmin_password }}'
    sampleuser:
      password: '{{ context.sampleuser_password }}'

You can find the full examples here: credentials_context_file, credentials_context_env.

Authentication

Enterprise Edition

Authentication features are supported by the Enterprise Edition only.

Authentication restrictions

Tarantool Enterprise Edition provides the ability to apply additional restrictions for user authentication. For example, you can specify the minimum time between authentication attempts or turn off access for guest users.

In the configuration below, security.auth_retries is set to 2, which means that Tarantool lets a client try to authenticate with the same username three times. At the fourth attempt, the authentication delay configured with security.auth_delay is enforced. This means that a client should wait 10 seconds after the first failed attempt.

security:
  auth_delay: 10
  auth_retries: 2
  disable_guest: true

The disable_guest option turns off access over remote connections from unauthenticated or guest users.

Password policy

A password policy allows you to improve database security by enforcing the use of strong passwords, setting up a maximum password age, and so on. When you create a new user with box.schema.user.create or update the password of an existing user with box.schema.user.passwd, the password is checked against the configured password policy settings.

In the example below, the following options are specified:

security:
  password_min_length: 16
  password_enforce_lowercase: true
  password_enforce_uppercase: true
  password_enforce_digits: true
  password_enforce_specialchars: true
  password_lifetime_days: 365
  password_history_length: 3

Authentication protocol

By default, Tarantool uses the CHAP protocol to authenticate users and applies SHA-1 hashing to passwords. Note that CHAP stores password hashes in the _user space unsalted. If an attacker gains access to the database, they may crack a password, for example, using a rainbow table.

In the Enterprise Edition, you can enable PAP authentication with the SHA256 hashing algorithm. For PAP, a password is salted with a user-unique salt before saving it in the database, which keeps the database protected from cracking using a rainbow table.

To enable PAP, specify the security.auth_type option as follows:

security:
  auth_type: 'pap-sha256'

For new users, the box.schema.user.create method generates authentication data using PAP-SHA256. For existing users, you need to reset a password using box.schema.user.passwd to use the new authentication protocol.

Предупреждение

Given that PAP transmits a password as plain text, Tarantool requires configuring SSL/TLS for a connection.

The example below shows how to specify the authentication protocol using the auth_type parameter when connecting to an instance using net.box:

local connection = require('net.box').connect({
    uri = 'admin:topsecret@127.0.0.1:3301',
    params = { auth_type = 'pap-sha256',
               transport = 'ssl',
               ssl_cert_file = 'certs/server.crt',
               ssl_key_file = 'certs/server.key' }
})

If the authentication protocol isn’t specified explicitly on the client side, the client uses the protocol configured on the server via security.auth_type.

Security

This section contains guides related to security features.

Журнал аудита

Enterprise Edition

The audit module is available in the Enterprise Edition only.

Example on GitHub: audit_log

The audit module allows you to record various events occurred in Tarantool. Each event is an action related to authorization and authentication, data manipulation, administrator activity, or system events.

The module provides detailed reports of these activities and helps you find and fix breaches to protect your business. For example, you can see who created a new user and when.

It is up to each company to decide exactly what activities to audit and what actions to take. System administrators, security engineers, and people in charge of the company may want to audit different events for different reasons. Tarantool provides such an option for each of them.

Configure audit log

The section describes how to enable and configure audit logging and write logs to a selected destination – a file, a pipe, or a system logger.

Read more: Audit log configuration reference.

Enable audit logging

To enable audit logging, define the log location using the audit_log.to option in the configuration file. Possible log locations:

In the configuration below, the audit_log.to option is set to file. It means that the logs are written to a file. By default, audit logs are saved in the var/log/{{ instance_name }}/audit.log file. To specify the path to an audit log file explicitly, use the audit_log.file option.

audit_log:
  to: file
  file: 'audit_tarantool.log'

If you log to a file, Tarantool reopens the audit log at SIGHUP.

To disable audit logging, set the audit_log.to option to devnull.

Filter the events

Tarantool’s extensive filtering options help you write only the events you need to the audit log. To select the recorded events, use the audit_log.filter option. Its value can be a list of events and event groups. You can customize the filters and use different combinations of them for your purposes. Possible filtering options:

  • Filter by event. You can set a list of events to be recorded. For example, select password_change to monitor the users who have changed their passwords:

    audit_log:
  filter: [ password_change ]

  • Filter by group. You can specify a list of event groups to be recorded. For example, select auth and priv to see the events related to authorization and granted privileges:

    audit_log:
  filter: [ auth,priv ]

  • Filter by group and event. You can specify a group and a certain event depending on the purpose. In the configuration below, user_create, data_operations, ddl, and custom are selected to see the events related to:

    • user creation
    • space creation, altering, and dropping
    • data modification or selection from spaces
    • custom events (any events added manually using the audit module API)
    filter: [ user_create,data_operations,ddl,custom ]

Set the format of audit log events

Use the audit_log.format option to choose the format of audit log events – plain text, CSV, or JSON.

format: json

JSON is used by default. It is more convenient to receive log events, analyze them, and integrate them with other systems if needed. The plain format can be efficiently compressed. The CSV format allows you to view audit log events in tabular form.

Specify the spaces to be logged

The audit_log.spaces option is used to specify a list of space names for which data operation events should be logged.

In the configuration below, only the events from the bands space are logged:

spaces: [ bands ]

Specify the logging mode in DML events

If set to true, the audit_log.extract_key option forces the audit subsystem to log the primary key instead of a full tuple in DML operations.

extract_key: true

Examples of audit log entries

In this example, the following audit log configuration is used:

audit_log:
  to: file
  file: 'audit_tarantool.log'
  filter: [ user_create,data_operations,ddl,custom ]
  format: json
  spaces: [ bands ]
  extract_key: true

Create a space bands and check the logs in the file after the creation:

box.schema.space.create('bands')

The audit log entry for the space_create event might look as follows:

{
  "time": "2024-01-24T11:43:21.566+0300",
  "uuid": "26af0a7d-1052-490a-9946-e19eacc822c9",
  "severity": "INFO",
  "remote": "unix/:(socket)",
  "session_type": "console",
  "module": "tarantool",
  "user": "admin",
  "type": "space_create",
  "tag": "",
  "description": "Create space Bands"
}

Then insert one tuple to space:

box.space.bands:insert { 1, 'Roxette', 1986 }

If the extract_key option is set to true, the audit system prints the primary key instead of the full tuple:

{
  "time": "2024-01-24T11:45:42.358+0300",
  "uuid": "b437934d-62a7-419a-8d59-e3b33c688d7a",
  "severity": "VERBOSE",
  "remote": "unix/:(socket)",
  "session_type": "console",
  "module": "tarantool",
  "user": "admin",
  "type": "space_insert",
  "tag": "",
  "description": "Insert key [2] into space bands"
}

If the extract_key option is set to false, the audit system prints the full tuple like this:

{
  "time": "2024-01-24T11:45:42.358+0300",
  "uuid": "b437934d-62a7-419a-8d59-e3b33c688d7a",
  "severity": "VERBOSE",
  "remote": "unix/:(socket)",
  "session_type": "console",
  "module": "tarantool",
  "user": "admin",
  "type": "space_insert",
  "tag": "",
  "description": "Insert tuple [1, \"Roxette\", 1986] into space bands"
}

Audit log events

Events types

The Tarantool audit log module can record various events that you can monitor and decide whether you need to take actions:

  • Administrator activity – events related to actions performed by the administrator. For example, such logs record the creation of a user.
  • Access events – events related to authorization and authentication of users. For example, such logs record failed attempts to access secure data.
  • Data access and modification – events of data manipulation in the storage.
  • System events – events related to modification or configuration of resources. For example, such logs record the replacement of a space.
  • Custom events – any events added manually using the audit module API.

The full list of available audit log events is provided in the table below:

Событие Event type Severity level Пример
Audit log enabled for events audit_enable VERBOSE  
Custom events custom INFO (default)  
User authorized successfully auth_ok VERBOSE Authenticate user <USER>
User authorization failed auth_fail ALARM Failed to authenticate user <USER>
User logged out or quit the session disconnect VERBOSE Close connection
User created user_create INFO Create user <USER>
User dropped user_drop INFO Drop user <USER>
Role created role_create INFO Create role <ROLE>
Role dropped role_drop INFO Drop role <ROLE>
User disabled user_disable INFO Disable user <USER>
User enabled user_enable INFO Enable user <USER>
User granted rights user_grant_rights INFO Grant <PRIVILEGE> rights for <OBJECT_TYPE> <OBJECT_NAME> to user <USER>
User revoked rights user_revoke_rights INFO Revoke <PRIVILEGE> rights for <OBJECT_TYPE> <OBJECT_NAME> from user <USER>
Role granted rights role_grant_rights INFO Grant <PRIVILEGE> rights for <OBJECT_TYPE> <OBJECT_NAME> to role <ROLE>
Role revoked rights role_revoke_rights INFO Revoke <PRIVILEGE> rights for <OBJECT_TYPE> <OBJECT_NAME> from role <ROLE>
User password changed password_change INFO Change password for user <USER>
Failed attempt to access secure data (for example, personal records, details, geolocation) access_denied ALARM <ACCESS_TYPE> denied to <OBJECT_TYPE> <OBJECT_NAME>
Expressions with arguments evaluated in a string eval INFO Evaluate expression <EXPR>
Function called with arguments call VERBOSE Call function <FUNCTION> with arguments <ARGS>
Iterator key selected from space.index space_select VERBOSE Select <ITER_TYPE> <KEY> from <SPACE>.<INDEX>
Space created space_create INFO Create space <SPACE>
Space altered space_alter INFO Alter space <SPACE>
Space dropped space_drop INFO Drop space <SPACE>
Tuple inserted into space space_insert VERBOSE Insert tuple <TUPLE> into space <SPACE>
Tuple replaced in space space_replace VERBOSE Replace tuple <TUPLE> with <NEW_TUPLE> in space <SPACE>
Tuple deleted from space space_delete VERBOSE Delete tuple <TUPLE> from space <SPACE>

Примечание

The eval event displays data from the console module and the eval function of the net.box module. For more on how they work, see Module console and Module net.box – eval. To separate the data, specify console or binary in the session field.

Structure of audit log event

Each audit log event contains a number of fields that can be used to filter and aggregate the resulting logs. An example of a Tarantool audit log entry in JSON:

{
    "time": "2024-01-15T13:39:36.046+0300",
    "uuid": "cb44fb2b-5c1f-4c4b-8f93-1dd02a76cec0",
    "severity": "VERBOSE",
    "remote": "unix/:(socket)",
    "session_type": "console",
    "module": "tarantool",
    "user": "admin",
    "type": "auth_ok",
    "tag": "",
    "description": "Authenticate user Admin"
}

Each event consists of the following fields:

Field Описание Пример
time Time of the event 2024-01-15T16:33:12.368+0300
uuid Since 3.0.0. A unique identifier of audit log event cb44fb2b-5c1f-4c4b-8f93-1dd02a76cec0
severity Since 3.0.0. A severity level. Each system audit event has a severity level determined by its importance. Custom events have the INFO severity level by default. VERBOSE
remote Remote host that triggered the event unix/:(socket)
session_type Session type console
module Audit log module. Set to tarantool for system events; can be overwritten for custom events tarantool
user User who triggered the event admin
type Audit event type auth_ok
tag A text field that can be overwritten by the user  
description Human-readable event description Authenticate user Admin

Event groups

Built-in event groups are used to filter the event types that you want to audit. For example, you can set to record only authorization events or only events related to a space.

Tarantool provides the following event groups:

  • all – all events.

    Примечание

    Events call and eval are included only in the all group.

  • audit – audit_enable event.

  • auth – authorization events: auth_ok, auth_fail.

  • priv – events related to authentication, authorization, users, and roles: user_create, user_drop, role_create, role_drop, user_enable, user_disable, user_grant_rights, user_revoke_rights, role_grant_rights, role_revoke_rights.

  • ddl – events of space creation, altering, and dropping: space_create, space_alter, space_drop.

  • dml – events of data modification in spaces: space_insert, space_replace, space_delete.

  • data_operations – events of data modification or selection from spaces: space_select, space_insert, space_replace, space_delete.

  • compatibility – events available in Tarantool before the version 2.10.0. auth_ok, auth_fail, disconnect, user_create, user_drop, role_create, role_drop, user_enable, user_disable, user_grant_rights, user_revoke_rights, role_grant_rights. role_revoke_rights, password_change, access_denied. This group enables the compatibility with earlier Tarantool versions.

Предупреждение

Be careful when recording all and data_operations event groups. The more events you record, the slower the requests are processed over time. It is recommended that you select only those groups whose events your company needs to monitor and analyze.

Custom events

Tarantool provides an API for writing custom audit log events. To enable these events, specify the custom value in the audit_log.filter option:

filter: [ user_create,data_operations,ddl,custom ]

Log a custom event

To log an event, use the audit.log() function that takes one of the following values:

  • Message string. Printed to the audit log with type message:

    audit.log('Hello, Alice!')

  • Format string and arguments. Passed to string format and then output to the audit log with type message:

    audit.log('Hello, %s!', 'Bob')

  • Table with audit log field values. The table must contain at least one field – description.

    audit.log({ type = 'custom_hello', description = 'Hello, World!' })
audit.log({ type = 'custom_farewell', user = 'eve', module = 'custom', description = 'Farewell, Eve!' })

Alternatively, you can use audit.new() to create a new log module. This allows you to avoid passing all custom audit log fields each time audit.log() is called. The audit.new() function takes a table of audit log field values (same as audit.log()). The type of the log module for writing custom events must either be message or have the custom_ prefix.

local my_audit = audit.new({ type = 'custom_hello', module = 'my_module' })
my_audit:log('Hello, Alice!')
my_audit:log({ tag = 'admin', description = 'Hello, Bob!' })

Overwrite custom event fields

It is possible to overwrite most of the custom audit log fields using audit.new() or audit.log(). The only audit log field that cannot be overwritten is time.

audit.log({ type = 'custom_hello', description = 'Hello!',
            session_type = 'my_session', remote = 'my_remote' })

If omitted, the session_type is set to the current session type, remote is set to the remote peer address.

Примечание

To avoid confusion with system events, the value of the type field must either be message (default) or begin with the custom_ prefix. Otherwise, you receive the error message. Custom events are filtered out by default.

Severity level

By default, custom events have the INFO severity level. To override the level, you can:

  • specify the severity field
  • use a shortcut function

The following shortcuts are available:

Shortcut Equivalent
audit.verbose(...) audit.log({severity = 'VERBOSE', ...})
audit.info(...) audit.log({severity = 'INFO', ...})
audit.warning(...) audit.log({severity = 'WARNING', ...})
audit.alarm(...) audit.log({severity = 'ALARM', ...})

Example

audit.log({ severity = 'VERBOSE', description = 'Hello!' })

Tips

How many events can be recorded?

If you write to a file, the size of the Tarantool audit log is limited by the disk space. If you write to a system logger, the size of the Tarantool audit log is limited by the system logger. If you write to a pipe, the size of the Tarantool audit message is limited by the system buffer. If the audit_log.nonblock = false, if audit_log.nonblock = true, there is no limit.

How often should audit logs be reviewed?

Consider setting up a schedule in your company. It is recommended to review audit logs at least every 3 months.

How long should audit logs be stored?

It is recommended to store audit logs for at least one year.

What is the best way to process audit logs?

It is recommended to use SIEM systems for this issue.

Аудит безопасности

This document will help you audit the security of a Tarantool cluster. It explains certain security aspects, their rationale, and the ways to check them. For details on how to configure Tarantool Enterprise Edition and its infrastructure for each aspect, refer to the security hardening guide.

Шифрование внешнего трафика iproto

Tarantool uses the iproto binary protocol for replicating data between instances and also in the connector libraries.

Since version 2.10.0, the Enterprise Edition has the built-in support for using SSL to encrypt the client-server communications over binary connections. For details on enabling SSL encryption, see the Securing connections with SSL section of this document.

In case the built-in encryption is not enabled, we recommend using VPN to secure data exchange between data centers.

Закрытые порты iproto

Если в кластере Tarantool не используется iproto для внешних запросов, подключение к портам iproto должно разрешаться только между экземплярами Tarantool.

Подробнее о настройке портов для iproto см. в разделе advertise_uri в документации Cartridge.

Механизм HTTPS termination

Экземпляр Tarantool может принимать HTTP-подключения от внешних источников или при доступе к веб-интерфейсу администратора. Все такие подключения должны проходить через веб-сервер с HTTPS, работающий на том же хосте (например, nginx). Это требование относится как к виртуальным, так и к физическим хостам. Проведение HTTP-трафика через несколько отдельных хостов с механизмом HTTPS termination недостаточно безопасно.

Закрытые HTTP-порты

Tarantool accepts HTTP connections on a specific port. It must be only available on the same host for nginx to connect to it.

Убедитесь, что настроенный HTTP-порт закрыт, а HTTPS-порт ( по умолчанию 443) открыт.

Ограниченный доступ к административной консоли

Модуль console дает возможность подключиться к рабочему экземпляру и запускать пользовательский код Lua. Это полезная возможность для разработчиков и администраторов. В следующих примерах показано, как открыть соединение по TCP-порту и на UNIX-сокете.

console.listen(<port number>)
console.listen('/var/lib/tarantool/socket_name.sock')

Открывать административную консоль через TCP-порт всегда небезопасно. Убедитесь, что в коде нет вызовов формата console.listen(<port_number>).

При подключении через сокет требуется право write для директории /var/lib/tarantool. Убедитесь, что оно выдано только пользователю tarantool.

Ограничения для пользователя guest

Connecting to the instance with tt connect or tarantoolctl connect without user credentials (under the guest user) must be disabled.

Есть два способа проверить эту уязвимость:

For more details, refer to the documentation on access control.

Авторизация в веб-интерфейсе

Using the web interface must require logging in with a username and password.

Запуск под пользователем tarantool

Все экземпляры Tarantool должны работать под пользователем tarantool.

Ограничение доступа для пользователя tarantool

Пользователь tarantool не должен иметь права sudo. Кроме того, у него не должно быть пароля, чтобы не допустить входа через SSH или su.

Хранение двух и более снимков данных

Для надежности резервного копирования в экземпляре Tarantool должны храниться минимум два последних снимка данных. Не забудьте проверить каждый экземпляр.

The snapshot_count value determines the number of kept snapshots. Configuration values are primarily set in the configuration files but can be overridden with environment variables and command-line arguments. So, it’s best to check both the values in the configuration files and the actual values using the console:

tarantool> box.cfg.checkpoint_count
---
- 2

Включен журнал упреждающей записи (WAL)

Tarantool фиксирует все входящие данные в журнале упреждающей записи (WAL). WAL должен быть включен, чтобы в случае перезапуска экземпляра эти данные можно было восстановить.

Secure values of the wal.mode configuration option are write and fsync:

wal:
  dir: 'var/lib/{{ instance_name }}/wals'
  mode: 'write'

An exclusion from this requirement is when the instance is processing data, which can be freely rejected - for example, when Tarantool is used for caching. In this case, WAL can be disabled to reduce i/o load.

Уровень ведения журнала: INFO или выше

Уровень ведения журнала должен быть 5 (INFO), 6 (VERBOSE) или 7 (DEBUG). Тогда в случае нарушения безопасности в журналах приложения будет достаточно информации для расследования инцидента.

tarantool> box.cfg.log_level
---
- 5

Полный список существующих уровней см. в разделе справки по log_level.

Ведение журнала с помощью journald

В Tarantool для ведения журнала следует использовать journald.

Инструкции по повышению безопасности

This guide explains how to enhance security in your Tarantool Enterprise Edition’s cluster using built-in features and provides general recommendations on security hardening. If you need to perform a security audit of a Tarantool Enterprise cluster, refer to the security checklist.

Tarantool Enterprise Edition does not provide a dedicated API for security control. All the necessary configurations can be done via an administrative console or initialization code.

В Tarantool Enterprise есть следующие встроенные средства безопасности:

Аутентификация

Tarantool Enterprise поддерживает аутентификацию на основе паролей и допускает два типа соединений:

For more information on authentication and connection types, see the Безопасность section in Administration.

Кроме того, Tarantool предоставляет следующие функциональные возможности:

Управление доступом

Для администраторов Tarantool Enterprise предоставляет средства предотвращения несанкционированного доступа к базе данных и к определенным функциям.

Tarantool различает:

The following system spaces are used to store users and privileges:

For more information, see the Access control section.

Users who create objects (spaces, indexes, users, roles, sequences, and functions) in the database become their owners and automatically acquire privileges for what they create. For more information, see the Owners and privileges section.

Журнал аудита

В Tarantool Enterprise есть встроенный журнал аудита, в котором записываются такие события, как:

The audit log contains:

You can configure the following audit log options:

Для получения дополнительной информации о журналировании см. следующие разделы:

Права доступа к файлам журнала можно настроить, как для любого другого объекта файловой системы Unix – через chmod.

Рекомендации по повышению безопасности

В этом разделе даны рекомендации, которые могут помочь вам повысить безопасность кластера.

Encrypting traffic

Since version 2.10.0, Tarantool Enterprise Edition has built-in support for using SSL to encrypt the client-server communications over binary connections, that is, between Tarantool instances in a cluster. For details on enabling SSL encryption, see the Securing connections with SSL section of this guide.

In case the built-in encryption is not set for particular connections, consider the following security recommendations:

  • настроить туннелирование соединения или
  • зашифровать сами данные, которые хранятся в базе.

For more information on data encryption, see the crypto module reference.

The HTTP server module provided by rocks does not support the HTTPS protocol. To set up a secure connection for a client (e.g., REST service), consider hiding the Tarantool instance (router if it is a cluster of instances) behind an Nginx server and setting up an SSL certificate for it.

To make sure that no information can be intercepted „from the wild“, run nginx on the same physical server as the instance and set up their communication over a Unix socket. For more information, see the socket module reference.

Настройка брандмауэра

To protect the cluster from any unwanted network activity „from the wild“, configure the firewall on each server to allow traffic on ports listed in Network requirements.

Если вы используете статические IP-адреса, повторно внесите их в белый список на каждом сервере, поскольку кластер работает на принципах полносвязной топологии (full mesh topology). Рекомендуется внести в черный список всех остальные адреса на всех серверах, кроме роутера (работающего за сервером Nginx).

Tarantool Enterprise не предоставляет защиту от DoS-атак или DDoS-атак. Для этих целей рекомендуется использовать сторонние программы.

Целостность данных

Tarantool Enterprise Edition does not keep checksums or provide the means to control data integrity. However, it ensures data persistence using a write-ahead log, regularly snapshots the entire data set to disk, and checks the data format whenever it reads the data back from the disk. For more information, see the Data persistence section.

Триггеры

Триггеры, которые также называют обратными вызовами, представляют собой функции, которые выполняет сервер при наступлении определенных событий.

Чтобы связать событие с колбэк-функцией, передайте её в соответствующую функцию обработки событий on_event:

Тогда сервер сохранит колбэк-функцию и будет вызывать ее при наступлении соответствующего события.

У всех триггеров есть следующие особенности:

Пример:

Здесь мы записываем события подключения и отключения в журнал на сервере Tarantool.

log = require('log')

function on_connect_impl()
 log.info("connected "..box.session.peer()..", sid "..box.session.id())
end

function on_disconnect_impl()
 log.info("disconnected, sid "..box.session.id())
end

function on_auth_impl(user)
 log.info("authenticated sid "..box.session.id().." as "..user)
end

function on_connect() pcall(on_connect_impl) end
function on_disconnect() pcall(on_disconnect_impl) end
function on_auth(user) pcall(on_auth_impl, user) end

box.session.on_connect(on_connect)
box.session.on_disconnect(on_disconnect)
box.session.on_auth(on_auth)

Applications

Using Tarantool as an application server, you can write your own applications. Tarantool’s native language for writing applications is Lua, so a typical application would be a file that contains your Lua script. But you can also write applications in C or C++.

Launching an application

Using Tarantool as an application server, you can write your own applications. Tarantool’s native language for writing applications is Lua, so a typical application would be a file that contains your Lua script. But you can also write applications in C or C++.

Примечание

If you’re new to Lua, we recommend going over the interactive Tarantool tutorial before proceeding with this chapter. To launch the tutorial, say tutorial() in Tarantool console:

tarantool> tutorial()
---
- |
 Tutorial -- Screen #1 -- Hello, Moon
 ====================================

 Welcome to the Tarantool tutorial.
 It will introduce you to Tarantool’s Lua application server
 and database server, which is what’s running what you’re seeing.
 This is INTERACTIVE -- you’re expected to enter requests
 based on the suggestions or examples in the screen’s text.
 <...>

Let’s create and launch our first Lua application for Tarantool. Here’s a simplest Lua application, the good old «Hello, world!»:

#!/usr/bin/env tarantool
print('Hello, world!')

We save it in a file. Let it be myapp.lua in the current directory.

Now let’s discuss how we can launch our application with Tarantool.

Launching in Docker

If we run Tarantool in a Docker container, the following command will start Tarantool without any application:

$ # create a temporary container and run it in interactive mode
$ docker run --rm -t -i tarantool/tarantool:latest

To run Tarantool with our application, we can say:

$ # create a temporary container and
$ # launch Tarantool with our application
$ docker run --rm -t -i \
             -v `pwd`/myapp.lua:/opt/tarantool/myapp.lua \
             -v /data/dir/on/host:/var/lib/tarantool \
             tarantool/tarantool:latest tarantool /opt/tarantool/myapp.lua

Here two resources on the host get mounted in the container:

By convention, the directory for Tarantool application code inside a container is /opt/tarantool, and the directory for data is /var/lib/tarantool.

Launching a binary program

If we run Tarantool from a package or from a source build, we can launch our application:

The simplest way is to pass the filename to Tarantool at start:

$ tarantool myapp.lua
Hello, world!
$

Tarantool starts, executes our script in the script mode and exits.

Now let’s turn this script into a server application. We use box.cfg from Tarantool’s built-in Lua module to:

We also add some simple database logic, using space.create() and create_index() to create a space with a primary index. We use the function box.once() to make sure that our logic will be executed only once when the database is initialized for the first time, so we don’t try to create an existing space or index on each invocation of the script:

#!/usr/bin/env tarantool
-- Configure database
box.cfg {
   listen = 3301
}
box.once("bootstrap", function()
   box.schema.space.create('tweedledum')
   box.space.tweedledum:create_index('primary',
       { type = 'TREE', parts = {1, 'unsigned'}})
end)

Now we launch our application in the same manner as before:

$ tarantool myapp.lua
Hello, world!
2017-08-11 16:07:14.250 [41436] main/101/myapp.lua C> version 2.1.0-429-g4e5231702
2017-08-11 16:07:14.250 [41436] main/101/myapp.lua C> log level 5
2017-08-11 16:07:14.251 [41436] main/101/myapp.lua I> mapping 1073741824 bytes for tuple arena...
2017-08-11 16:07:14.255 [41436] main/101/myapp.lua I> recovery start
2017-08-11 16:07:14.255 [41436] main/101/myapp.lua I> recovering from `./00000000000000000000.snap'
2017-08-11 16:07:14.271 [41436] main/101/myapp.lua I> recover from `./00000000000000000000.xlog'
2017-08-11 16:07:14.271 [41436] main/101/myapp.lua I> done `./00000000000000000000.xlog'
2017-08-11 16:07:14.272 [41436] main/102/hot_standby I> recover from `./00000000000000000000.xlog'
2017-08-11 16:07:14.274 [41436] iproto/102/iproto I> binary: started
2017-08-11 16:07:14.275 [41436] iproto/102/iproto I> binary: bound to [::]:3301
2017-08-11 16:07:14.275 [41436] main/101/myapp.lua I> done `./00000000000000000000.xlog'
2017-08-11 16:07:14.278 [41436] main/101/myapp.lua I> ready to accept requests

This time, Tarantool executes our script and keeps working as a server, accepting TCP requests on port 3301. We can see Tarantool in the current session’s process list:

$ ps | grep "tarantool"
  PID TTY           TIME CMD
41608 ttys001       0:00.47 tarantool myapp.lua <running>

But the Tarantool instance will stop if we close the current terminal window. To detach Tarantool and our application from the terminal window, we can launch it in the daemon mode. To do so, we add some parameters to box.cfg{}:

For example:

box.cfg {
   listen = 3301,
   background = true,
   log = '1.log',
   pid_file = '1.pid'
}

We launch our application in the same manner as before:

$ tarantool myapp.lua
Hello, world!
$

Tarantool executes our script, gets detached from the current shell session (you won’t see it with ps | grep "tarantool") and continues working in the background as a daemon attached to the global session (with SID = 0):

$ ps -ef | grep "tarantool"
  PID SID     TIME  CMD
42178   0  0:00.72 tarantool myapp.lua <running>

Now that we have discussed how to create and launch a Lua application for Tarantool, let’s dive deeper into programming practices.

Application roles

An application role is a Lua module that implements specific functions or logic. You can turn on or off a particular role for certain instances in a configuration without restarting these instances. A role is run when a configuration is loaded or reloaded.

Roles can be divided into the following groups:

This section describes how to develop custom roles. To learn how to enable and configure roles, see Enabling and configuring roles.

Примечание

Don’t confuse application roles with other role types:

Providing a role configuration

A custom role can be configured in the same way as roles provided by Tarantool or third-party Lua modules. You can learn more from Enabling and configuring roles.

This example shows how to enable and configure the greeter role, which is implemented in the next section:

instance001:
  roles: [ greeter ]
  roles_cfg:
    greeter:
      greeting: 'Hi'

The role configuration provided in roles_cfg can be accessed when validating and applying this configuration.

Tarantool includes the experimental.config.utils.schema built-in module that provides tools for managing user-defined configurations of applications (app.cfg) and roles (roles_cfg). The examples below show its basic usage.

Given that a role is a Lua module, a role name is passed to require() to obtain the module. When developing an application, you can place a file with the role code next to the cluster configuration file.

Creating a custom role

Overview

Creating a custom role includes the following steps:

  1. (Optional) Define the role configuration schema.
  2. Define a function that validates a role configuration.
  3. Define a function that applies a validated configuration.
  4. Define a function that stops a role.
  5. (Optional) Define roles from which this custom role depends on.

As a result, a role module should return an object that has corresponding functions and fields specified:

return {
    validate = function() -- ... -- end,
    apply = function() -- ... -- end,
    stop = function() -- ... -- end,
    dependencies = { -- ... -- },
}

The examples below show how to do this.

Примечание

Code snippets shown in this section are included from the following application: application_role_cfg.

Defining the role configuration schema

The experimental.config.utils.schema built-in module provides the schema_object class. An object of this class defines a custom configuration scheme of a role or an application.

This example shows how to define a schema that reflects the role configuration shown above:

local greeter_schema = schema.new('greeter', schema.record({
    greeting = schema.scalar({
        type = 'string',
        allowed_values = { 'Hi', 'Hello' }
    })
}))

If you don’t use the module, skip this step. In this case, use the cfg argument of the role’s validate() and apply() functions to refer to its configuration values, for example, cfg.greeting.

Validating a role configuration

To validate a role configuration, you need to define the validate([cfg]) function.

In the example below, the validate() function of the role configuration schema is used to validate the greeting value:

local function validate(cfg)
    greeter_schema:validate(cfg)
end

If the configuration is not valid, validate() reports an unrecoverable error by throwing an error object.

Applying a role configuration

To apply the validated configuration, define the apply([cfg]) function. As the validate() function, apply() provides access to a role’s configuration using the cfg argument.

In the example below, the apply() function uses the log module to write a value from the role configuration to the log:

local function apply(cfg)
    log.info("%s from the 'greeter' role!", greeter_schema:get(cfg, 'greeting'))
end

Stopping a role

To stop a role, use the stop() function.

In the example below, the stop() function uses the log module to indicate that a role is stopped:

local function stop()
    log.info("The 'greeter' role is stopped")
end

When you’ve defined all the role functions, you need to return an object that has corresponding functions specified:

return {
    validate = validate,
    apply = apply,
    stop = stop,
}

Role dependencies

To define a role’s dependencies, use the dependencies field. In this example, the byeer role has the greeter role as the dependency:

-- byeer.lua --
local log = require('log').new("byeer")

return {
    dependencies = { 'greeter' },
    validate = function() end,
    apply = function() log.info("Bye from the 'byeer' role!") end,
    stop = function() end,
}

A role cannot be started without its dependencies. This means that all the dependencies of a role should be defined in the roles configuration parameter:

instance001:
  roles: [ greeter, byeer ]

You can find the full example here: application_role_cfg.

Adding initialization code

You can add initialization code to a role by defining and calling a function with an arbitrary name at the top level of a module, for example:

local function init()
    -- ... --
end

init()

For example, you can create spaces, define indexes, or grant privileges to specific users or roles.

See also: Specifics of creating spaces.

Specifics of creating spaces

To create a space in a role, you need to make sure that the target instance is in read-write mode (its box.info.ro is false). You can check an instance state by subscribing to the box.status event using box.watch():

box.watch('box.status', function()
    -- creating a space
    -- ...
end)

Примечание

Given that a role may be enabled when an instance is already in read-write mode, you also need to execute schema initialization code from apply(). To make sure a space is created only once, use the if_not_exists option.

Roles life cycle

A role’s life cycle includes the stages described below.

  1. Loading roles

    On each run, all roles are loaded in the order they are specified in the configuration. This stage takes effect when a role is enabled or an instance with this role is restarted. At this stage, a role executes the initialization code.

    A role cannot be started if it has dependencies that are not specified in a configuration.

    Примечание

    Dependencies do not affect the order in which roles are loaded. However, the validate(), apply(), and stop() functions are executed taking dependencies into account. Learn more in Executing functions for dependent roles.

  1. Stopping roles

    This stage takes effect during a configuration reload when a role is removed from the configuration for a given instance. Note that all stop() calls are performed before any validate() or apply() calls. This means that old roles are stopped first, and only then new roles are started.

  1. Validating a role’s configurations

    At this stage, a configuration for each role is validated using the corresponding validate() function in the same order in which they are specified in the configuration.

  1. Applying a role’s configurations

    At this stage, a configuration for each role is applied using the corresponding apply() function in the same order in which they are specified in the configuration.

All role’s functions report an unrecoverable error by throwing an error object. If an error is thrown in any phase, applying a configuration is stopped. If starting or stopping a role throws an error, no roles are stopped or started afterward. An error is caught and shown in config:info() in the alerts section.

Executing functions for dependent roles

For roles that depend on each other, their validate(), apply(), and stop() functions are executed taking into account the dependencies. Suppose, there are three independent and two dependent roles:

role1
role2
role3
    └─── role4
             └─── role5
  • role1, role2, and role5 are independent roles.
  • role3 depends on role4, role4 depends on role5.

The roles are enabled in a configuration as follows:

roles: [ role1, role2, role3, role4, role5 ]

In this case, validate() and apply() for these roles are executed in the following order:

role1 -> role2 -> role5 -> role4 -> role3

Roles removed from a configuration are stopped in the order reversed to the order they are specified in a configuration, taking into account the dependencies. Suppose, all roles except role1 are removed from the configuration above:

roles: [ role1 ]

After reloading a configuration, stop() functions for the removed roles are executed in the following order:

role3 -> role4 -> role5 -> role2

Example: Role without a configuration

The example below shows how to enable the custom greeter role for instance001:

instance001:
  roles: [ greeter ]

The implementation of this role looks as follows:

-- greeter.lua --
return {
    validate = function() end,
    apply = function() require('log').info("Hi from the 'greeter' role!") end,
    stop = function() end,
}

Example on GitHub: application_role

Example: Role with a configuration

The example below shows how to enable the custom greeter role for instance001 and specify the configuration for this role:

instance001:
  roles: [ greeter ]
  roles_cfg:
    greeter:
      greeting: 'Hi'

The implementation of this role looks as follows:

-- greeter.lua --
local log = require('log').new("greeter")
local schema = require('experimental.config.utils.schema')

local greeter_schema = schema.new('greeter', schema.record({
    greeting = schema.scalar({
        type = 'string',
        allowed_values = { 'Hi', 'Hello' }
    })
}))

local function validate(cfg)
    greeter_schema:validate(cfg)
end

local function apply(cfg)
    log.info("%s from the 'greeter' role!", greeter_schema:get(cfg, 'greeting'))
end

local function stop()
    log.info("The 'greeter' role is stopped")
end

return {
    validate = validate,
    apply = apply,
    stop = stop,
}

Example on GitHub: application_role_cfg

Example: HTTP API

The example below shows how to enable and configure the http-api custom role:

instance001:
  roles: [ http-api ]
  roles_cfg:
    http-api:
      host: '127.0.0.1'
      port: 8080

The implementation of this role looks as follows:

-- http-api.lua --
local httpd
local json = require('json')
local schema = require('experimental.config.utils.schema')

local function validate_host(host, w)
    local host_pattern = "^(%d+)%.(%d+)%.(%d+)%.(%d+)$"
    if not host:match(host_pattern) then
        w.error("'host' should be a string containing a valid IP address, got %q", host)
    end
end

local function validate_port(port, w)
    if port <= 1 or port >= 65535 then
        w.error("'port' should be between 1 and 65535, got %d", port)
    end
end

local listen_address_schema = schema.new('listen_address', schema.record({
    host = schema.scalar({
        type = 'string',
        validate = validate_host,
        default = '127.0.0.1',
    }),
    port = schema.scalar({
        type = 'integer',
        validate = validate_port,
        default = 8080,
    }),
}))

local function validate(cfg)
    listen_address_schema:validate(cfg)
end

local function apply(cfg)
    if httpd then
        httpd:stop()
    end
    local cfg_with_defaults = listen_address_schema:apply_default(cfg)
    local host = listen_address_schema:get(cfg_with_defaults, 'host')
    local port = listen_address_schema:get(cfg_with_defaults, 'port')
    httpd = require('http.server').new(host, port)
    local response_headers = { ['content-type'] = 'application/json' }
    httpd:route({ path = '/band/:id', method = 'GET' }, function(req)
        local id = req:stash('id')
        local band_tuple = box.space.bands:get(tonumber(id))
        if not band_tuple then
            return { status = 404, body = 'Band not found' }
        else
            local band = { id = band_tuple['id'],
                           band_name = band_tuple['band_name'],
                           year = band_tuple['year'] }
            return { status = 200, headers = response_headers, body = json.encode(band) }
        end
    end)
    httpd:route({ path = '/band', method = 'GET' }, function(req)
        local limit = req:query_param('limit')
        if not limit then
            limit = 5
        end
        local band_tuples = box.space.bands:select({}, { limit = tonumber(limit) })
        local bands = {}
        for _, tuple in pairs(band_tuples) do
            local band = { id = tuple['id'],
                           band_name = tuple['band_name'],
                           year = tuple['year'] }
            table.insert(bands, band)
        end
        return { status = 200, headers = response_headers, body = json.encode(bands) }
    end)
    httpd:start()
end

local function stop()
    httpd:stop()
end

local function init()
    require('data'):add_sample_data()
end

init()

return {
    validate = validate,
    apply = apply,
    stop = stop,
}

Example on GitHub: application_role_http_api

API Reference

Members  
validate([cfg]) Validate a role’s configuration.
apply([cfg]) Apply a role’s configuration.
stop() Stop a role.
dependencies Define a role’s dependencies.
validate([cfg])

Validate a role’s configuration. This function is called on instance startup or when the configuration is reloaded for the instance with this role. Note that the validate() function is called regardless of whether the role’s configuration or any field in a cluster’s configuration is changed.

validate() should throw an error if the validation fails.

Параметры:
  • cfg – a role’s role configuration to be validated. This parameter provides access to configuration options defined in roles_cfg.<role_name>. To get values of configuration options placed outside roles_cfg.<role_name>, use config:get().

See also: Validating a role configuration

apply([cfg])

Apply a role’s configuration. apply() is called after validate() is executed for all the enabled roles. As the validate() function, apply() is called on instance startup or when the configuration is reloaded for the instance with this role.

apply() should throw an error if the specified configuration can’t be applied.

Примечание

Note that apply() is not invoked if an instance switches to read-write mode when replication.failover is set to election or supervised. You can check an instance state by subscribing to the box.status event using box.watch().

Параметры:
  • cfg – a role’s role configuration to be applied. This parameter provides access to configuration options defined in roles_cfg.<role_name>. To get values of configuration options placed outside roles_cfg.<role_name>, use config:get().

See also: Applying a role configuration

stop()

Stop a role. This function is called on configuration reload if the role is removed from roles for the given instance.

See also: Stopping a role

dependencies

(Optional) Define a role’s dependencies.

Rtype:table

See also: Role dependencies

Fibers, yields, and cooperative multitasking

Creating a fiber is the Tarantool way of making application logic work in the background at all times. A fiber is a set of instructions that are executed with cooperative multitasking: the instructions contain yield signals, upon which control is passed to another fiber.

Fibers

Fibers are similar to threads of execution in computing. The key difference is that threads use preemptive multitasking, while fibers use cooperative multitasking (see below). This gives fibers the following two advantages over threads:

Yet fibers have some limitations as compared with threads, the main limitation being no multi-core mode. All fibers in an application belong to a single thread, so they all use the same CPU core as the parent thread. Meanwhile, this limitation is not really serious for Tarantool applications, because a typical bottleneck for Tarantool is the HDD, not the CPU.

A fiber has all the features of a Lua coroutine and all programming concepts that apply for Lua coroutines will apply for fibers as well. However, Tarantool has made some enhancements for fibers and has used fibers internally. So, although the use of coroutines is possible and supported, the use of fibers is recommended.

Any live fiber can be in one of three states: running, suspended, and ready. After a fiber dies, the dead status returns.

To learn more about fibers, go to the fiber module documentation.

Yields

Yield is an action that occurs in a cooperative environment that transfers control of the thread from the current fiber to another fiber that is ready to execute.

Any live fiber can be in one of three states: running, suspended, and ready. After a fiber dies, the dead status is returned. By observing fibers from the outside, you can only see running (for the current fiber) and suspended for any other fiber waiting for an event from the event loop (ev) for execution.

../../../_images/yields.svg

After a yield has occurred, the next ready fiber is taken from the queue and executed. When there are no more ready fibers, execution is transferred to the event loop.

After a fiber has yielded and regained control, it immediately issues testcancel.

Yields can be explicit or implicit.

Explicit yields

Explicit yields are clearly visible from the invoking code. There are only two explicit yields: fiber.yield() and fiber.sleep(t).

  • fiber.yield() yields execution to another ready fiber while putting itself in the ready state, meaning that it will be executed again as soon as possible while being polite to other fibers waiting for execution.
  • fiber.sleep(t) yields execution to another ready fiber and puts itself in the suspended state for time t until time passes and the event loop wakes up this fiber to the ready state.

In general, it is good behavior for long-running cpu-intensive tasks to yield periodically to be cooperative to other waiting fibers.

Implicit yields

On the other hand, there are many operations, such as operations with sockets, file system, and disk I/O, which imply some waiting for the current fiber while others can be executed. When such an operation occurs, a possible blocking operation would be passed into the event loop and the fiber would be suspended until the resource is ready to continue fiber execution.

Here is the list of implicitly yielding operations:

  • Connection establishment (socket).
  • Socket read and write (socket).
  • Filesystem operations (from fio).
  • Channel data transfer (fiber.channel).
  • File input/output (from fio).
  • Console operations (since console is a socket).
  • HTTP requests (since HTTP is a socket operation).
  • Database modifications (if they imply a disk write).
  • Database reading for the vinyl engine.
  • Invocation of another process (popen).

Примечание

Please note that all operations of the os module are non-cooperative and exclusively block the whole tx thread.

For memtx, since all data is in memory, there is no yielding for a read request (like :select, :pairs, :get).

For vinyl, since some data may not be in memory, there may be disk I/O for a read (to fetch data from disk) or write (because a stall may occur while waiting for memory to be freed).

For both memtx and vinyl, since data change requests must be recorded in the WAL, there is normally a box.commit().

With the default autocommit mode the following operations are yielding:

To provide atomicity for transactions in transaction mode, some changes are applied to the modification operations for the memtx engine. After executing box.begin or within a box.atomic call, any modification operation will not yield, and yield will occur only on box.commit or upon return from box.atomic. Meanwhile, box.rollback does not yield.

That is why executing separate commands like select(), insert(), update() in the console inside a transaction without MVCC will cause it to an abort. This is due to implicit yield after each chunk of code is executed in the console.

Example #1

  • Engine = memtx.
space:get()
space:insert()

The sequence has one yield, at the end of the insert, caused by implicit commit; get() has nothing to write to the WAL and so does not yield.

  • Engine = memtx.
box.begin()
space1:get()
space1:insert()
space2:get()
space2:insert()
box.commit()

The sequence has one yield, at the end of the box.commit, none of the inserts are yielding.

  • Engine = vinyl.
space:get()
space:insert()

The sequence has one to three yields, since get() may yield if the data is not in the cache, insert() may yield if it waits for available memory, and there is an implicit yield at commit.

  • Engine = vinyl.
box.begin()
space1:get()
space1:insert()
space2:get()
space2:insert()
box.commit()

The sequence may yield from 1 to 5 times.

Example #2

Assume that there are tuples in the memtx space tester where the third field represents a positive dollar amount.

Let’s start a transaction, withdraw from tuple#1, deposit in tuple#2, and end the transaction, making its effects permanent.

tarantool> function txn_example(from, to, amount_of_money)
         >   box.atomic(function()
         >     box.space.tester:update(from, {{'-', 3, amount_of_money}})
         >     box.space.tester:update(to,   {{'+', 3, amount_of_money}})
         >   end)
         >   return "ok"
         > end

Result:
---
...
tarantool> txn_example({999}, {1000}, 1.00)
---
- "ok"
...

If wal_mode = none, then there is no implicit yielding at the commit time because there are no writes to the WAL.

If a request if performed via network connector such as net.box and implies sending requests to the server and receiving responses, then it involves network I/O and thus implicit yielding. Even if the request that is sent to the server has no implicit yield. Therefore, the following sequence causes yields three times sequentially when sending requests to the network and awaiting the results.

conn.space.test:get{1}
conn.space.test:get{2}
conn.space.test:get{3}

Cooperative multitasking

Cooperative multitasking means that unless a running fiber deliberately yields control, it is not preempted by some other fiber. But a running fiber will deliberately yield when it encounters a «yield point»: a transaction commit, an operating system call, or an explicit «yield» request. Any system call which can block will be performed asynchronously, and any running fiber which must wait for a system call will be preempted, so that another ready-to-run fiber takes its place and becomes the new running fiber.

This model makes all programmatic locks unnecessary: cooperative multitasking ensures that there will be no concurrency around a resource, no race conditions, and no memory consistency issues. The way to achieve this is simple: Use no yields, explicit or implicit in critical sections, and no one can interfere with code execution.

For small requests, such as simple UPDATE or INSERT or DELETE or SELECT, fiber scheduling is fair: it takes little time to process the request, schedule a disk write, and yield to a fiber serving the next client.

However, a function may perform complex calculations or be written in such a way that yields take a long time to occur. This can lead to unfair scheduling when a single client throttles the rest of the system, or to apparent stalls in processing requests. It is the responsibility of the function author to avoid this situation. As a protective mechanism, a fiber slice can be used.

Примеры и рекомендации по разработке на Lua

Ниже представлены дополнения в виде Lua-программ для часто встречающихся или сложных случаев.

Любую из этих программ можно выполнить, скопировав код в .lua-файл, а затем выполнив в командной строке chmod +x ./имя-программы.lua и :samp :./{имя-программы}.lua.

Первая строка – это шебанг:

#!/usr/bin/env tarantool

Он запускает сервер приложений Tarantool на языке Lua, который должен быть в пути выполнения.

В этом разделе собраны следующие рецепты:

Можно использовать свободно.

Другие рецепты см. на GitHub Tarantool.

hello_world.lua

Стандартный пример простой программы.

#!/usr/bin/env tarantool

 print('Hello, World!')

console_start.lua

Для инициализации базы данных (создания спейсов) используйте box.once(), если сервер запускается впервые. Затем используйте console.start(), чтобы запустить интерактивный режим.

#!/usr/bin/env tarantool

-- Настроить базу данных
box.cfg {
    listen = 3313
}

box.once("bootstrap", function()
    box.schema.space.create('tweedledum')
    box.space.tweedledum:create_index('primary',
        { type = 'TREE', parts = {1, 'unsigned'}})
end)

require('console').start()

fio_read.lua

Используйте Модуль fio, чтобы открыть, прочитать и закрыть файл.

#!/usr/bin/env tarantool

local fio = require('fio')
local errno = require('errno')
local f = fio.open('/tmp/xxxx.txt', {'O_RDONLY' })
if not f then
    error("Failed to open file: "..errno.strerror())
end
local data = f:read(4096)
f:close()
print(data)

fio_write.lua

Используйте Модуль fio, чтобы открыть, записать данные и закрыть файл.

#!/usr/bin/env tarantool

local fio = require('fio')
local errno = require('errno')
local f = fio.open('/tmp/xxxx.txt', {'O_CREAT', 'O_WRONLY', 'O_APPEND'},
    tonumber('0666', 8))
if not f then
    error("Failed to open file: "..errno.strerror())
end
f:write("Hello\n");
f:close()

ffi_printf.lua

Используйте Библиотеку LuaJIT FFI, чтобы вызвать встроенную в C функцию: printf(). (Чтобы лучше понимать FFI, см. Учебное пособие по FFI.)

#!/usr/bin/env tarantool

local ffi = require('ffi')
ffi.cdef[[
    int printf(const char *format, ...);
]]

ffi.C.printf("Hello, %s\n", os.getenv("USER"));

ffi_gettimeofday.lua

Используйте Библиотеку LuaJIT FFI, чтобы вызвать встроенную в C функцию: gettimeofday(). Она позволяет получить значение времени с точностью в миллисекундах, в отличие от функции времени в Tarantool Модуль clock.

#!/usr/bin/env tarantool

local ffi = require('ffi')
ffi.cdef[[
    typedef long time_t;
    typedef struct timeval {
    time_t tv_sec;
    time_t tv_usec;
} timeval;
    int gettimeofday(struct timeval *t, void *tzp);
]]

local timeval_buf = ffi.new("timeval")
local now = function()
    ffi.C.gettimeofday(timeval_buf, nil)
    return tonumber(timeval_buf.tv_sec * 1000 + (timeval_buf.tv_usec / 1000))
end

ffi_zlib.lua

Используйте Библиотеку LuaJIT FFI, чтобы вызвать библиотечную функцию в C. (Чтобы лучше понимать FFI, см. Учебное пособие по FFI.)

#!/usr/bin/env tarantool

local ffi = require("ffi")
ffi.cdef[[
    unsigned long compressBound(unsigned long sourceLen);
    int compress2(uint8_t *dest, unsigned long *destLen,
    const uint8_t *source, unsigned long sourceLen, int level);
    int uncompress(uint8_t *dest, unsigned long *destLen,
    const uint8_t *source, unsigned long sourceLen);
]]
local zlib = ffi.load(ffi.os == "Windows" and "zlib1" or "z")

-- Надстройка Lua для функции compress2()
local function compress(txt)
    local n = zlib.compressBound(#txt)
    local buf = ffi.new("uint8_t[?]", n)
    local buflen = ffi.new("unsigned long[1]", n)
    local res = zlib.compress2(buf, buflen, txt, #txt, 9)
    assert(res == 0)
    return ffi.string(buf, buflen[0])
end

-- Надстройка Lua для функции uncompress
local function uncompress(comp, n)
    local buf = ffi.new("uint8_t[?]", n)
    local buflen = ffi.new("unsigned long[1]", n)
    local res = zlib.uncompress(buf, buflen, comp, #comp)
    assert(res == 0)
    return ffi.string(buf, buflen[0])
end

-- Простой код теста
local txt = string.rep("abcd", 1000)
print("Uncompressed size: ", #txt)
local c = compress(txt)
print("Compressed size: ", #c)
local txt2 = uncompress(c, #txt)
assert(txt2 == txt)

ffi_meta.lua

Используйте Библиотеку LuaJIT FFI, чтобы получить доступ к объекту в C с помощью метаметода (метод, который определен метатаблицей).

#!/usr/bin/env tarantool

local ffi = require("ffi")
ffi.cdef[[
typedef struct { double x, y; } point_t;
]]

local point
local mt = {
  __add = function(a, b) return point(a.x+b.x, a.y+b.y) end,
  __len = function(a) return math.sqrt(a.x*a.x + a.y*a.y) end,
  __index = {
    area = function(a) return a.x*a.x + a.y*a.y end,
  },
}
point = ffi.metatype("point_t", mt)

local a = point(3, 4)
print(a.x, a.y)  --> 3  4
print(#a)        --> 5
print(a:area())  --> 25
local b = a + point(0.5, 8)
print(#b)        --> 12.5

count_array.lua

Используйте оператор „#“, чтобы получить количество элементов в Lua-таблице типа массива. У этой операции сложность O(log(N)).

#!/usr/bin/env tarantool

array = { 1, 2, 3}
print(#array)

count_array_with_nils.lua

Отсутствующие элементы в массивах, которые Lua рассматривает как nil, заставляют простой оператор „#“ выдавать неправильные результаты. Команда «print(#t)» выведет «4», команда «print(counter)» выведет «3», а команда «print(max)» – «10». Другие табличные функции, такие как table.sort(), также сработают неправильно при наличии нулевых значений nil.

#!/usr/bin/env tarantool

local t = {}
t[1] = 1
t[4] = 4
t[10] = 10
print(#t)
local counter = 0
for k,v in pairs(t) do counter = counter + 1 end
print(counter)
local max = 0
for k,v in pairs(t) do if k > max then max = k end end
print(max)

count_array_with_nulls.lua

Используйте явные значения``NULL``, чтобы избежать проблем, вызванных nil в Lua == поведение с пропущенными значениями. Хотя json.NULL == nil является true, все команды вывода в данной программе выведут правильное значение: 10.

#!/usr/bin/env tarantool

local json = require('json')
local t = {}
t[1] = 1; t[2] = json.NULL; t[3]= json.NULL;
t[4] = 4; t[5] = json.NULL; t[6]= json.NULL;
t[6] = 4; t[7] = json.NULL; t[8]= json.NULL;
t[9] = json.NULL
t[10] = 10
print(#t)
local counter = 0
for k,v in pairs(t) do counter = counter + 1 end
print(counter)
local max = 0
for k,v in pairs(t) do if k > max then max = k end end
print(max)

count_map.lua

Программа используется для получения количества элементов в таблице типа ассоциативного массива.

#!/usr/bin/env tarantool

local map = { a = 10, b = 15, c = 20 }
local size = 0
for _ in pairs(map) do size = size + 1; end
print(size)

swap.lua

Программа использует особенность Lua менять местами две переменные без необходимости использования третьей переменной.

#!/usr/bin/env tarantool

local x = 1
local y = 2
x, y = y, x
print(x, y)

class.lua

Используется для создания класса, метатаблицы для класса, экземпляра класса. Другой пример можно найти в http://lua-users.org/wiki/LuaClassesWithMetatable.

#!/usr/bin/env tarantool

-- определить объекты класса
local myclass_somemethod = function(self)
    print('test 1', self.data)
end

local myclass_someothermethod = function(self)
    print('test 2', self.data)
end

local myclass_tostring = function(self)
    return 'MyClass <'..self.data..'>'
end

local myclass_mt = {
    __tostring = myclass_tostring;
    __index = {
        somemethod = myclass_somemethod;
        someothermethod = myclass_someothermethod;
    }
}

-- создать новый объект своего класса myclass
local object = setmetatable({ data = 'data'}, myclass_mt)
print(object:somemethod())
print(object.data)

garbage.lua

Запустите сборщик мусора в Lua с помощью функции collectgarbage.

#!/usr/bin/env tarantool

collectgarbage('collect')

fiber_producer_and_consumer.lua

Запустите один файбер для производителя и один файбер для потребителя. Используйте fiber.channel() для обмена данных и синхронизации. Можно настроить ширину канала (ch_size в программном коде) для управления количеством одновременных задач к обработке.

#!/usr/bin/env tarantool

local fiber = require('fiber')
local function consumer_loop(ch, i)
    -- инициализировать потребитель синхронно или выдать ошибку()
    fiber.sleep(0) -- позволить fiber.create() продолжать
    while true do
        local data = ch:get()
        if data == nil then
            break
        end
        print('consumed', i, data)
        fiber.sleep(math.random()) -- моделировать работу
    end
end

local function producer_loop(ch, i)
    -- инициализировать потребитель синхронно или выдать ошибку()
    fiber.sleep(0) -- allow fiber.create() to continue
    while true do
        local data = math.random()
        ch:put(data)
        print('produced', i, data)
    end
end

local function start()
    local consumer_n = 5
    local producer_n = 3

    -- создать канал
    local ch_size = math.max(consumer_n, producer_n)
    local ch = fiber.channel(ch_size)

    -- запустить потребители
    for i=1, consumer_n,1 do
        fiber.create(consumer_loop, ch, i)
    end

    -- запустить производители
    for i=1, producer_n,1 do
        fiber.create(producer_loop, ch, i)
    end
end

start()
print('started')

socket_tcpconnect.lua

Используйте socket.tcp_connect() для подключения к удаленному серверу по TCP. Можно отобразить информацию о подключении и результат запроса GET.

#!/usr/bin/env tarantool

local s = require('socket').tcp_connect('google.com', 80)
print(s:peer().host)
print(s:peer().family)
print(s:peer().type)
print(s:peer().protocol)
print(s:peer().port)
print(s:write("GET / HTTP/1.0\r\n\r\n"))
print(s:read('\r\n'))
print(s:read('\r\n'))

socket_tcp_echo.lua

Используйте socket.tcp_connect() для настройки простого TCP-сервера путем создания функции, которая обрабатывает запросы и отражает их, а затем передачи функции на socket.tcp_server(). Данная программа была протестирована на 100 000 клиентов, каждый из которых получил отдельный файбер.

#!/usr/bin/env tarantool

local function handler(s, peer)
    s:write("Welcome to test server, " .. peer.host .."\n")
    while true do
        local line = s:read('\n')
        if line == nil then
            break -- ошибка или конец файла
        end
        if not s:write("pong: "..line) then
            break -- ошибка или конец файла
        end
    end
end

local server, addr = require('socket').tcp_server('localhost', 3311, handler)

getaddrinfo.lua

Используйте socket.getaddrinfo(), чтобы провести неблокирующее разрешение имен DNS, получая как AF_INET6, так и AF_INET информацию для „google.com“. Данная техника не всегда необходима для TCP-соединений, поскольку socket.tcp_connect() выполняет socket.getaddrinfo с точки зрения внутреннего устройства до попытки соединения с первым доступным адресом.

#!/usr/bin/env tarantool

local s = require('socket').getaddrinfo('google.com', 'http', { type = 'SOCK_STREAM' })
print('host=',s[1].host)
print('family=',s[1].family)
print('type=',s[1].type)
print('protocol=',s[1].protocol)
print('port=',s[1].port)
print('host=',s[2].host)
print('family=',s[2].family)
print('type=',s[2].type)
print('protocol=',s[2].protocol)
print('port=',s[2].port)

socket_udp_echo.lua

В данный момент в Tarantool нет функции udp_server, поэтому socket_udp_echo.lua – более сложная программа, чем socket_tcp_echo.lua. Ее можно реализовать с помощью сокетов и файберов.

#!/usr/bin/env tarantool

local socket = require('socket')
local errno = require('errno')
local fiber = require('fiber')

local function udp_server_loop(s, handler)
    fiber.name("udp_server")
    while true do
        -- попытка прочитать сначала датаграмму
        local msg, peer = s:recvfrom()
        if msg == "" then
            -- сокет был закрыт с помощью s:close()
            break
        elseif msg ~= nil then
            -- получена новая датаграмма
            handler(s, peer, msg)
        else
            if s:errno() == errno.EAGAIN or s:errno() == errno.EINTR then
                -- сокет не готов
                s:readable() -- передача управления, epoll сообщит, когда будут новые данные
            else
                -- ошибка сокета
                local msg = s:error()
                s:close() -- сохранить ресурсы и не ждать сборку мусора
                error("Socket error: " .. msg)
            end
        end
    end
end

local function udp_server(host, port, handler)
    local s = socket('AF_INET', 'SOCK_DGRAM', 0)
    if not s then
        return nil -- проверить номер ошибки errno:strerror()
   end
    if not s:bind(host, port) then
        local e = s:errno() -- сохранить номер ошибки errno
        s:close()
        errno(e) -- восстановить номер ошибки errno
        return nil -- проверить номер ошибки errno:strerror()
    end

    fiber.create(udp_server_loop, s, handler) -- запустить новый файбер в фоновом режиме
    return s
end

Функция для клиента, который подключается к этому серверу, может выглядеть следующим образом:

local function handler(s, peer, msg)
    -- Необязательно ждать, пока сокет будет готов отправлять UDP
    -- s:writable()
    s:sendto(peer.host, peer.port, "Pong: " .. msg)
end

local server = udp_server('127.0.0.1', 3548, handler)
if not server then
    error('Failed to bind: ' .. errno.strerror())
end

print('Started')

require('console').start()

http_get.lua

Используйте Модуль HTTP для получения данных по HTTP.

#!/usr/bin/env tarantool

local http_client = require('http.client')
local json = require('json')
local r = http_client.get('https://api.frankfurter.app/latest?to=USD%2CRUB')
if r.status ~= 200 then
    print('Failed to get currency ', r.reason)
    return
end
local data = json.decode(r.body)
print(data.base, 'rate of', data.date, 'is', data.rates.RUB, 'RUB or', data.rates.USD, 'USD')

http_send.lua

Используйте Модуль HTTP для отправки данных по HTTP.

#!/usr/bin/env tarantool

local http_client = require('http.client')
local json = require('json')
local data = json.encode({ Key = 'Value'})
local headers = { Token = 'xxxx', ['X-Secret-Value'] = '42' }
local r = http_client.post('http://localhost:8081', data, { headers = headers})
if r.status == 200 then
    print 'Success'
end

http_server.lua

Используйте сторонний модуль http (который необходимо предварительно установить), чтобы превратить Tarantool в веб-сервер.

#!/usr/bin/env tarantool

local function handler(self)
    return self:render{ json = { ['Your-IP-Is'] = self.peer.host } }
end

local server = require('http.server').new(nil, 8080, {charset = "utf8"}) -- прослушивание *:8080
server:route({ path = '/' }, handler)
server:start()
-- подключение к localhost:8080 и просмотр json

http_generate_html.lua

Use the http rock (which must first be installed) to generate HTML pages from templates. The http rock has a fairly simple template engine which allows execution of regular Lua code inside text blocks (like PHP). Therefore there is no need to learn new languages in order to write templates.

#!/usr/bin/env tarantool

local function handler(self)
local fruits = { 'Apple', 'Orange', 'Grapefruit', 'Banana'}
    return self:render{ fruits = fruits }
end

local server = require('http.server').new(nil, 8080, {charset = "utf8"}) -- nil означает '*'
server:route({ path = '/', file = 'index.html.lua' }, handler)
server:start()

HTML-файл для этого сервера, включая Lua, может выглядеть следующим образом (будет выведено «1 Apple | 2 Orange | 3 Grapefruit | 4 Banana»). Создайте директорию templates и поместите в неё файл:

<html>
<body>
    <table border="1">
        % for i,v in pairs(fruits) do
        <tr>
            <td><%= i %></td>
            <td><%= v %></td>
        </tr>
        % end
    </table>
</body>
</html>

select_all.go

На языке Go выборка содержимого всего спейса не является тривиальной задачей, которая решается в одну строчку. Ниже мы приводим пример программы, которая осуществляет полную выборку из спейса „tester“. Эту программу нужно вызвать на том экземпляре, с которым вы собираетесь установить соединение через Go-коннектор.

package main

import (
	"fmt"
	"log"

	"github.com/tarantool/go-tarantool"
)

/*
box.cfg{listen = 3301}
box.schema.user.passwd('pass')

s = box.schema.space.create('tester')
s:format({
    {name = 'id', type = 'unsigned'},
    {name = 'band_name', type = 'string'},
    {name = 'year', type = 'unsigned'}
})
s:create_index('primary', { type = 'hash', parts = {'id'} })
s:create_index('scanner', { type = 'tree', parts = {'id', 'band_name'} })

s:insert{1, 'Roxette', 1986}
s:insert{2, 'Scorpions', 2015}
s:insert{3, 'Ace of Base', 1993}
*/

func main() {
	conn, err := tarantool.Connect("127.0.0.1:3301", tarantool.Opts{
		User: "admin",
		Pass: "pass",
	})

	if err != nil {
		log.Fatalf("Connection refused")
	}
	defer conn.Close()

	spaceName := "tester"
	indexName := "scanner"
	idFn := conn.Schema.Spaces[spaceName].Fields["id"].Id
	bandNameFn := conn.Schema.Spaces[spaceName].Fields["band_name"].Id

	var tuplesPerRequest uint32 = 2
	cursor := []interface{}{}

	for {
		resp, err := conn.Select(spaceName, indexName, 0, tuplesPerRequest, tarantool.IterGt, cursor)
		if err != nil {
			log.Fatalf("Failed to select: %s", err)
		}

		if resp.Code != tarantool.OkCode {
			log.Fatalf("Select failed: %s", resp.Error)
		}

		if len(resp.Data) == 0 {
			break
		}

		fmt.Println("Iteration")

		tuples := resp.Tuples()
		for _, tuple := range tuples {
			fmt.Printf("\t%v\n", tuple)
		}

		lastTuple := tuples[len(tuples)-1]
		cursor = []interface{}{lastTuple[idFn], lastTuple[bandNameFn]}
	}
}

Практические задания на Lua

Первые шаги

Если вы только осваиваете Lua, рекомендуем выполнить практическое задание, встроенное в Tarantool. Чтобы начать работу с этим заданием, выполните команду tutorial() в консоли Tarantool:

tarantool> tutorial()
---
- |
 Tutorial -- Screen #1 -- Hello, Moon
 ====================================

 Welcome to the Tarantool tutorial.
 It will introduce you to Tarantool’s Lua application server
 and database server, which is what’s running what you’re seeing.
 This is INTERACTIVE -- you’re expected to enter requests
 based on the suggestions or examples in the screen’s text.
 <...>

Вставка 1 млн кортежей с помощью хранимой процедуры на языке Lua

Задание по данному практикуму: “Вставьте 1 миллион кортежей. В каждом кортеже должно быть поле, которое соответствует ключу в первичном индексе, в виде постоянно возрастающего числа, а также поле в виде буквенной строки со случайным значением из 10 символов.”

Цель данного упражнения состоит в том, чтобы показать, как выглядят Lua-функции в Tarantool. Необходимо будет работать с математической библиотекой Lua, библиотекой для работы со строками интерпретатора Lua, Tarantool-библиотекой box, Tarantool-библиотекой box.tuple, циклами и конкатенацией. Инструкции легко будет выполнять даже тем, кто никогда не использовал раньше Lua или Tarantool. Единственное требование – знание того, как работают другие языки программирования, и изучение первых двух глав данного руководства. Но для лучшего понимания можно следовать по комментариям и ссылкам на руководство по Lua или другим пунктам в данном руководстве по Tarantool. А чтобы облегчить изучение, читайте инструкции параллельно с вводом операторов в Tarantool-клиент.

Настройка

Будем использовать Tarantool-песочницу, которую создавали для упражнений раздела «Руководство для начинающих». Таким образом, у нас есть один спейс и числовой ключ первичного индекса, а также экземпляр Tarantool, который также выступает в виде клиента.

Разделитель

В более ранних версиях Tarantool многострочные функции обрамляются символами-разделителями. Сейчас в них нет необходимости, поэтому в данном практическом задании они использоваться не будут. Однако они все еще поддерживаются. Если вы хотите использовать разделители или используете более раннюю версию Tarantool, перед работой проверьте описание синтаксиса для объявления разделителя.

Создание функции, которая возвращает строку

Начнем с создания функции, которая возвращает заданную строку – “Hello world”.

function string_function()
  return "hello world"
end

Слово «function» (функция) – ключевое слово в языке Lua. Рассмотрим подробно работу с языком Lua. Имя функции – string_function (строковая_функция). В функции есть один исполняемый оператор, return "hello world" (вернуть «hello world»). Строка «hello world» здесь заключена в двойные кавычки, хотя в Lua это не имеет значения, можно использовать одинарные кавычки. Слово «end» означает, что “это конец объявления Lua-функции.” Чтобы проверить работу функции, можем выполнить команду

string_function()

Отправка function-name() (имя-функции) означает команду вызова Lua-функции. В результате возвращаемая функцией строка появится на экране.

Для получения подробной информации о строках в языке Lua, см. Главу 2.4 «Строки» в руководстве по языку Lua. Для получения подробной информации о функциях см. Главу 5 «Функции» в руководстве по языку Lua (chapter 5 «Functions»).

Теперь вывод на экране выглядит следующим образом:

tarantool> function string_function()
         >   return "hello world"
         > end
---
...
tarantool> string_function()
---
- hello world
...
tarantool>

Создание функции, которая вызывает другую функцию и определяет переменную

Теперь у нас есть функция string_function, и можно вызвать ее с помощью другой функции.

function main_function()
  local string_value
  string_value = string_function()
  return string_value
end

Сначала объявим переменную «string_value» (значение_строки). Слово «local» (локально) означает, что string_value появится только в main_function (основная_функция). Если бы мы не использовали «local», то string_value увидели бы даже пользователи других клиентов, которые подключились к данному экземпляру! Иногда это может быть очень полезно при взаимодействии клиентов, но не в нашем случае.

Затем определим значение для string_value, а именно, результат функции string_function(). Сейчас вызовем main_function(), чтобы проверить, что значение определено.

Для получения подробной информации о переменных в языке Lua, см. Главу 4.2 «Локальные переменные и блоки» в руководстве по языку Lua (chapter 4.2 «Local Variables and Blocks»).

Теперь вывод на экране выглядит следующим образом:

tarantool> function main_function()
         >   local string_value
         >   string_value = string_function()
         >   return string_value
         > end
---
...
tarantool> main_function()
---
- hello world
...
tarantool>

Изменение функции для возврата строки из одной случайной буквы

Сейчас стало понятно, как задавать переменную, поэтому можно изменить функцию string_function() так, чтобы вместо возврата заданной фразы «Hello world», она возвращала случайным образом выбранную букву от „A“ до „Z“.

function string_function()
  local random_number
  local random_string
  random_number = math.random(65, 90)
  random_string = string.char(random_number)
  return random_string
end

Нет необходимости стирать содержание старой функции string_function(), оно просто перезаписывается. Первый оператор вызывает функцию из математической библиотеки Lua, которая возвращает случайное число; параметры означают, что число должно быть целым от 65 до 90. Второй оператор вызывает функцию из библиотеки Lua для работы со строками, которая преобразует число в символ; параметр представляет собой кодовую точку символа. К счастью, в кодировке ASCII символу „A“ соответствует значение 65, а „Z“ – 90, так что в результате всегда получим букву от A до Z.

For more about Lua math-library functions see Lua users «Math Library Tutorial». For more about Lua string-library functions see Lua users «String Library Tutorial» .

И снова функцию string_function() можно вызвать из main_function(), которую можно вызвать с помощью main_function().

Теперь вывод на экране выглядит следующим образом:

tarantool> function string_function()
         >   local random_number
         >   local random_string
         >   random_number = math.random(65, 90)
         >   random_string = string.char(random_number)
         >   return random_string
         > end
---
...
tarantool> main_function()
---
- C
...
tarantool>

… На самом деле, вывод не всегда будет именно таким, поскольку функция math.random() вызывает случайные числа. Но для наглядности случайные значения в строке не важны.

Изменение функции для возврата строки из десяти случайных букв

Сейчас стало понятно, как вызывать строки из одной случайной буквы, поэтому можно перейти к нашей цели – возврату строки из десяти букв с помощью конкатенации десяти строк из одной случайной буквы в цикле.

function string_function()
  local random_number
  local random_string
  random_string = ""
  for x = 1,10,1 do
    random_number = math.random(65, 90)
    random_string = random_string .. string.char(random_number)
  end
  return random_string
end

Слова «for x = 1,10,1» означают: “начать с x, равного 1, зацикливать до тех пор, пока x не будет равен 10, увеличивать x на 1 на каждом шаге цикла”. Символ «..» означает «конкатенацию», то есть добавление строки справа от знака «..» к строке слева от знака «..». Поскольку в начале определяется, что random_string (случайная_строка) представляет собой «» (пустую строку), в результате получим, что в random_string 10 случайных букв. И снова функцию string_function() можно вызвать из main_function(), которую можно вызвать с помощью main_function().

Для получения подробной информации о циклах в языке Lua, см. Главу 4.3.4 «Числовой оператор for» в руководстве по языку Lua (chapter 4.3.4 «Numeric for»).

Теперь вывод на экране выглядит следующим образом:

tarantool> function string_function()
         >   local random_number
         >   local random_string
         >   random_string = ""
         >   for x = 1,10,1 do
         >     random_number = math.random(65, 90)
         >     random_string = random_string .. string.char(random_number)
         >   end
         >   return random_string
         > end
---
...
tarantool> main_function()
---
- 'ZUDJBHKEFM'
...
tarantool>

Составление кортежа из числа и строки

Сейчас стало понятно, как создать строку из 10 случайных букв, поэтому можно создать кортеж, который будет содержать число и строку из 10 случайных букв, с помощью функции в Tarantool-библиотеке Lua-функций.

function main_function()
  local string_value, t
  string_value = string_function()
  t = box.tuple.new({1, string_value})
  return t
end

После этого, «t» будет представлять собой значение нового кортежа с двумя полями. Первое поле является числовым: «1». Второе поле представляет собой случайную строку. И снова функцию string_function() можно вызвать из main_function(), которую можно вызвать с помощью main_function().

Для получения подробной информации о кортежах в Tarantool, см. раздел Вложенный модуль box.tuple руководства по Tarantool.

Теперь вывод на экране выглядит следующим образом:

tarantool> function main_function()
         > local string_value, t
         > string_value = string_function()
         > t = box.tuple.new({1, string_value})
         > return t
         > end
---
...
tarantool> main_function()
---
- [1, 'PNPZPCOOKA']
...
tarantool>

Изменение основной функции main_function для вставки кортежа в базу данных

Сейчас стало понятно, как создавать кортеж, который содержит число и строку из десяти случайных букв, поэтому осталось только поместить этот кортеж в спейс tester. Следует отметить, что tester – это первый спейс, определенный в песочнице, поэтому он представляет собой таблицу в базе данных.

function main_function()
  local string_value, t
  string_value = string_function()
  t = box.tuple.new({1,string_value})
  box.space.tester:replace(t)
end

Здесь новая строка – box.space.tester:replace(t). Имя содержит слово „tester“, потому что вставка будет осуществляться в спейс tester. Второй параметр представляет собой значение в кортеже. Для абсолютной точности мы могли ввести команду box.space.tester:insert(t), а не box.space.tester:replace(t), но слово «replace» (заменить) означает “вставить, даже если уже существует кортеж, у которого значение первичного ключа совпадает”, и это облегчит повтор упражнения, даже если песочница не пуста. После того, как это будет выполнено, спейс tester будет содержать кортеж с двумя полями. Первое поле будет 1. Второе поле будет представлять собой строку из десяти случайных букв. И снова функцию string_function() можно вызвать из main_function(), которую можно вызвать с помощью main_function(). Но функция main_function() не может полностью отразить ситуацию, поскольку она не возвращает t, она только размещает t в базе данных. Чтобы убедиться, что произошла вставка, используем SELECT-запрос.

main_function()
         box.space.tester:select{1}

Для получения подробной информации о вызовах insert и replace в Tarantool, см. разделы Вложенный модуль box.space, space_object:insert() и space_object:replace() руководства по Tarantool.

Теперь вывод на экране выглядит следующим образом:

tarantool> function main_function()
         >   local string_value, t
         >   string_value = string_function()
         >   t = box.tuple.new({1,string_value})
         >   box.space.tester:replace(t)
         > end
---
...
tarantool> main_function()
---
...
tarantool> box.space.tester:select{1}
---
- - [1, 'EUJYVEECIL']
...
tarantool>

Изменение основной функции main_function для вставки миллиона кортежей в базу данных

Сейчас стало понятно, как вставить кортеж в базу данных, поэтому несложно догадаться, как можно увеличить масштаб: вместо того, чтобы вставлять значение 1 для первичного ключа, вставьте значение переменной от 1 до миллиона в цикле. Поскольку уже рассматривалось, как заводить цикл, это будет несложно. Мы лишь добавим небольшой штрих – функцию распределения во времени.

function main_function()
  local string_value, t
  for i = 1,1000000,1 do
    string_value = string_function()
    t = box.tuple.new({i,string_value})
    box.space.tester:replace(t)
  end
end
start_time = os.clock()
main_function()
end_time = os.clock()
'insert done in ' .. end_time - start_time .. ' seconds'

Стандартная Lua-функция os.clock() вернет время ЦП в секундах с момента начала программы. Таким образом, выводя start_time = number of seconds (время_начала = число секунд) прямо перед вставкой, а затем выводя end_time = number of seconds (время_окончания = число секунд) сразу после вставки, можно рассчитать (время_окончания - время_начала) = затраченное время в секундах. Отобразим это значение путем ввода в запрос без операторов, что приведет к тому, что Tarantool отправит значение на клиент, который выведет это значение. (Ответ Lua на C-функцию printf(), а именно print(), также сработает.)

Для получения подробной информации о функции os.clock() см. Главу 22.1 «Дата и время» в руководстве по языку Lua (chapter 22.1 «Date and Time»). Для получения подробной информации о функции print() см. Главу 5 «Функции» в руководстве по языку Lua (chapter 5 «Functions»).

И поскольку наступает кульминация – повторно введем окончательные варианты всех необходимых запросов: запрос, который создает string_function(), запрос, который создает main_function(), и запрос, который вызывает main_function().

function string_function()
           local random_number
           local random_string
           random_string = ""
           for x = 1,10,1 do
             random_number = math.random(65, 90)
             random_string = random_string .. string.char(random_number)
           end
           return random_string
         end

         function main_function()
           local string_value, t
           for i = 1,1000000,1 do
             string_value = string_function()
             t = box.tuple.new({i,string_value})
             box.space.tester:replace(t)
           end
         end
         start_time = os.clock()
         main_function()
         end_time = os.clock()
         'insert done in ' .. end_time - start_time .. ' seconds'

Теперь вывод на экране выглядит следующим образом:

tarantool> function string_function()
         >   local random_number
         >   local random_string
         >   random_string = ""
         >   for x = 1,10,1 do
         >     random_number = math.random(65, 90)
         >     random_string = random_string .. string.char(random_number)
         >   end
         >   return random_string
         > end
---
...
tarantool> function main_function()
         >   local string_value, t
         >   for i = 1,1000000,1 do
         >     string_value = string_function()
         >     t = box.tuple.new({i,string_value})
         >     box.space.tester:replace(t)
         >   end
         > end
---
...
tarantool> start_time = os.clock()
---
...
tarantool> main_function()
---
...
tarantool> end_time = os.clock()
---
...
tarantool> 'insert done in ' .. end_time - start_time .. ' seconds'
---
- insert done in 37.62 seconds
...
tarantool>

Итак, мы доказали, что возможности Lua-функций довольно многообразны (на самом деле, с помощью хранимых процедур на языке Lua в Tarantool можно сделать больше, чем с помощью хранимых процедур в некоторых SQL СУБД), и несложно комбинировать функции Lua-библиотек и функции Tarantool-библиотек.

Также мы показали, что вставка миллиона кортежей заняла 37 секунд. Хостом выступил ноутбук с ОС Linux. А изменив значение wal_mode на „none“ перед запуском теста, можно уменьшить затраченное время до 4 секунд.

Подсчет суммы по JSON-полям во всех кортежах

Задание по данному практикуму: “Предположим, что в каждом кортеже есть строка в формате JSON. В каждой строке есть числовое поле формата JSON. Для каждого кортежа необходимо найти значение числового поля и прибавить его к переменной „sum“ (сумма). В конце функция должна вернуть переменную „sum“.” Цель данного упражнения – получить опыт в прочтении и обработке кортежей одновременно.

 1json = require('json')
 2function sum_json_field(field_name)
 3  local v, t, sum, field_value, is_valid_json, lua_table
 4  sum = 0
 5  for v, t in box.space.tester:pairs() do
 6    is_valid_json, lua_table = pcall(json.decode, t[2])
 7    if is_valid_json then
 8      field_value = lua_table[field_name]
 9      if type(field_value) == "number" then sum = sum + field_value end
10    end
11  end
12  return sum
13end

СТРОКА 3: ЗАЧЕМ НУЖЕН «LOCAL». Эта строка объявляет все переменные, которые будут использоваться в функции. На самом деле, нет необходимости в начале объявлять все переменные, а в длинной функции лучше объявить переменные прямо перед их использованием. Фактически объявлять переменные вообще необязательно, но необъявленная переменная будет «глобальной». Это представляется нежелательным для всех переменных, объявленных в строке 1, поскольку все они используются только в рамках функции.

СТРОКА 5: ЗАЧЕМ НУЖЕН «PAIRS()». Наша задача – пройти по всем строкам, что можно сделать двумя способами: с помощью box.space.space_object:pairs() или с помощью variable = select(...) с указанием for i, n, 1 do некая-функция(variable[i]) end. Для данного примера мы предпочли использовать pairs().

СТРОКА 5: НАЧАЛО ОСНОВНОГО ЦИКЛА. Всё внутри цикла «for» будет повторяться до тех пор, пока не кончатся индекс-ключи. На полученный кортеж можно сослаться с помощью переменной t.

LINE 6: WHY «PCALL». If we simply said lua_table = json.decode(t[2])), then the function would abort with an error if it encountered something wrong with the JSON string - a missing colon, for example. By putting the function inside «pcall» (protected call), we’re saying: we want to intercept that sort of error, so if there’s a problem just set is_valid_json = false and we will know what to do about it later.

СТРОКА 6: ЗНАЧЕНИЕ. Функция json.decode означает декодирование JSON-строки, а параметр t[2] представляет собой ссылку на JSON-строку. Здесь есть заранее заданные значения, а мы предполагаем, что JSON-строка была вставлена во второе поле кортежа. Например, предположим, что кортеж выглядит следующим образом:

field[1]: 444
field[2]: '{"Hello": "world", "Quantity": 15}'

что означает, что первое поле кортежа, первичное поле, представляет собой число, а второе поле кортежа, JSON-строка, является строкой. Таким образом, значение оператора будет следующим: «декодировать t[2] (второе поле кортежа) как JSON-строку; если обнаружится ошибка, то указать is_valid_json = false; если ошибок нет, указать is_valid_json = true и lua_table = Lua-таблица, в которой находится декодированная строка».

СТРОКА 8. Наконец, мы готовы получить значение JSON-поля из Lua-таблицы, взятое из JSON-строки. Значение в field_name (имя_поля), которое является параметром всей функции, должно представлять собой JSON-поле. Например, в JSON-строке '{"Hello": "world", "Quantity": 15}' есть два JSON-поля: «Hello» и «Quantity». Если вся функция вызывается с помощью sum_json_field("Quantity"), тогда field_value = lua_table[field_name] (значение_поля = Lua_таблица[имя_поля]) по сути аналогично field_value = lua_table["Quantity"] или даже field_value = lua_table.Quantity. Итак, этими тремя способами можно ввести следующую команду: получить значение поля Quantity в Lua-таблице и поместить его в переменную field_value.

СТРОКА 9: ЗАЧЕМ НУЖЕН «IF». Предположим, что JSON-строка не содержит синтаксических ошибок, но JSON-поле не является числовым или вовсе отсутствует. В таком случае выполнение функции прервется при попытке прибавить значение к сумме. Если сначала проверить, type(field_value) == "number" (тип(значение_поля) == «число»), можно избежать прерывания функции. Если вы уверены, что база данных в идеальном состоянии, этот шаг можно пропустить.

И функция готова. Пора протестировать ее. Начинаем с пустой базы данных так же, как с песочницы в упражнения в «Руководстве для начинающих»,

-- если спейс tester остался от предыдущего задания, удалите его
box.space.tester:drop()
box.schema.space.create('tester')
box.space.tester:create_index('primary', {parts = {1, 'unsigned'}})

затем добавим несколько кортежей, где первое поле является числовым, а второе поле представляет собой строку.

box.space.tester:insert{444, '{"Item": "widget", "Quantity": 15}'}
box.space.tester:insert{445, '{"Item": "widget", "Quantity": 7}'}
box.space.tester:insert{446, '{"Item": "golf club", "Quantity": "sunshine"}'}
box.space.tester:insert{447, '{"Item": "waffle iron", "Quantit": 3}'}

Для целей практики здесь допущены ошибки. В «golf club» и «waffle iron» поля Quantity не являются числовыми, поэтому будут игнорироваться. Таким образом, итоговая сумма для полей Quantity в JSON-строках должна быть следующей: 15 + 7 = 22.

Вызовите функцию с помощью sum_json_field("Quantity").

tarantool> sum_json_field("Quantity")
---
- 22
...

It works. We’ll just leave, as exercises for future improvement, the possibility that the «hard coding» assumptions could be removed, that there might have to be an overflow check if some field values are huge, and that the function should contain a yield instruction if the count of tuples is huge.

Tips on Lua syntax

The Lua syntax for data-manipulation functions can vary. Here are examples of the variations with select() requests. The same rules exist for the other data-manipulation functions.

Every one of the examples does the same thing: select a tuple set from a space named „tester“ where the primary-key field value equals 1. For these examples, we assume that the numeric id of „tester“ is 512, which happens to be the case in our sandbox example only.

Object reference variations

First, there are three object reference variations:

-- #1 module . submodule . name
tarantool> box.space.tester:select{1}
-- #2 replace name with a literal in square brackets
tarantool> box.space['tester']:select{1}
-- #3 use a variable for the entire object reference
tarantool> s = box.space.tester
tarantool> s:select{1}

Examples in this manual usually have the «box.space.tester:» form (#1). However, this is a matter of user preference and all the variations exist in the wild.

Also, descriptions in this manual use the syntax «space_object:» for references to objects which are spaces, and «index_object:» for references to objects which are indexes (for example box.space.tester.index.primary:).

Parameter variations

Then, there are seven parameter variations:

-- #1
tarantool> box.space.tester:select{1}
-- #2
tarantool> box.space.tester:select({1})
-- #3
tarantool> box.space.tester:select(1)
-- #4
tarantool> box.space.tester.select(box.space.tester,1)
-- #5
tarantool> box.space.tester:select({1},{iterator='EQ'})
-- #6
tarantool> variable = 1
tarantool> box.space.tester:select{variable}
-- #7
tarantool> variable = {1}
tarantool> box.space.tester:select(variable)

Lua allows to omit parentheses () when invoking a function if its only argument is a Lua table, and we use it sometimes in our examples. This is why select{1} is equivalent to select({1}). Literal values such as 1 (a scalar value) or {1} (a Lua table value) may be replaced by variable names, as in examples #6 and #7.

Although there are special cases where braces can be omitted, they are preferable because they signal «Lua table». Examples and descriptions in this manual have the {1} form. However, this too is a matter of user preference and all the variations exist in the wild.

Rules for object names

Database objects have loose rules for names: the maximum length is 65000 bytes (not characters), and almost any legal Unicode character is allowed, including spaces, ideograms and punctuation.

In those cases, to prevent confusion with Lua operators and separators, object references should have the literal-in-square-brackets form (#2), or the variable form (#3). For example:

tarantool> box.space['1*A']:select{1}
tarantool> s = box.space['1*A !@$%^&*()_+12345678901234567890']
tarantool> s:select{1}

Disallowed:

Not recommended: characters which cannot be displayed.

Names are «case sensitive», so „A“ and „a“ are not the same.

Enterprise modules

This section covers open and closed source Lua modules for Tarantool Enterprise Edition included in the distribution as an offline rocks repository.

Open source modules

Closed source modules

Installing and using modules

To use a module, install the following:

  1. All the necessary third-party software packages (if any). See the module’s prerequisites for the list.

  2. The module itself on every Tarantool instance:

    $ tt rocks install MODULE_NAME [MODULE_VERSION]

See the tt rocks reference to learn more about managing Lua modules.

Создание приложения

Further we walk you through key programming practices that will give you a good start in writing Lua applications for Tarantool. We will implement a real microservice based on Tarantool! It is a backend for a simplified version of Pokémon Go, a location-based augmented reality game launched in mid-2016.

In this game, players use the GPS capability of a mobile device to locate, catch, battle, and train virtual monsters called «pokémon» that appear on the screen as if they were in the same real-world location as the player.

To stay within the walk-through format, let’s narrow the original gameplay as follows. We have a map with pokémon spawn locations. Next, we have multiple players who can send catch-a-pokémon requests to the server (which runs our Tarantool microservice). The server responds whether the pokémon is caught or not, increases the player’s pokémon counter if yes, and triggers the respawn-a-pokémon method that spawns a new pokémon at the same location in a while.

We leave client-side applications outside the scope of this story. However, we promise a mini-demo in the end to simulate real users and give us some fun.

../../../_images/aster.svg

Follow these topics to implement our application:

Modules, rocks and applications

To make our game logic available to other developers and Lua applications, let’s put it into a Lua module.

A module (called «rock» in Lua) is an optional library which enhances Tarantool functionality. So, we can install our logic as a module in Tarantool and use it from any Tarantool application or module. Like applications, modules in Tarantool can be written in Lua (rocks), C or C++.

Modules are good for two things:

Technically, a module is a file with source code that exports its functions in an API. For example, here is a Lua module named mymodule.lua that exports one function named myfun:

local exports = {}
exports.myfun = function(input_string)
   print('Hello', input_string)
end
return exports

To launch the function myfun() – from another module, from a Lua application, or from Tarantool itself, – we need to save this module as a file, then load this module with the require() directive and call the exported function.

For example, here’s a Lua application that uses myfun() function from mymodule.lua module:

-- loading the module
local mymodule = require('mymodule')

-- calling myfun() from within test() function
local test = function()
  mymodule.myfun()
end

A thing to remember here is that the require() directive takes load paths to Lua modules from the package.path variable. This is a semicolon-separated string, where a question mark is used to interpolate the module name. By default, this variable contains system-wide Lua paths and the working directory. But if we put our modules inside a specific folder (e.g. scripts/), we need to add this folder to package.path before any calls to require():

package.path = 'scripts/?.lua;' .. package.path

For our microservice, a simple and convenient solution would be to put all methods in a Lua module (say pokemon.lua) and to write a Lua application (say game.lua) that initializes the gaming environment and starts the game loop.

../../../../_images/aster1.svg

Now let’s get down to implementation details. In our game, we need three entities:

We’ll store these entities as tuples in Tarantool spaces. But to deliver our backend application as a microservice, the good practice would be to send/receive our data in the universal JSON format, thus using Tarantool as a document storage.

Avro schemas

To store JSON data as tuples, we will apply a savvy practice which reduces data footprint and ensures all stored documents are valid. We will use Tarantool module avro-schema which checks the schema of a JSON document and converts it to a Tarantool tuple. The tuple will contain only field values, and thus take a lot less space than the original document. In avro-schema terms, converting JSON documents to tuples is «flattening», and restoring the original documents is «unflattening».

First you need to install the module with tt rocks install avro-schema.

Further usage is quite straightforward:

  1. For each entity, we need to define a schema in Apache Avro schema syntax, where we list the entity’s fields with their names and Avro data types.
  2. At initialization, we call avro-schema.create() that creates objects in memory for all schema entities, and compile() that generates flatten/unflatten methods for each entity.
  3. Further on, we just call flatten/unflatten methods for a respective entity on receiving/sending the entity’s data.

Here’s what our schema definitions for the player and pokémon entities look like:

local schema = {
    player = {
        type="record",
        name="player_schema",
        fields={
            {name="id", type="long"},
            {name="name", type="string"},
            {
                name="location",
                type= {
                    type="record",
                    name="player_location",
                    fields={
                        {name="x", type="double"},
                        {name="y", type="double"}
                    }
                }
            }
        }
    },
    pokemon = {
        type="record",
        name="pokemon_schema",
        fields={
            {name="id", type="long"},
            {name="status", type="string"},
            {name="name", type="string"},
            {name="chance", type="double"},
            {
                name="location",
                type= {
                    type="record",
                    name="pokemon_location",
                    fields={
                        {name="x", type="double"},
                        {name="y", type="double"}
                    }
                }
            }
        }
    }
}

And here’s how we create and compile our entities at initialization:

-- load avro-schema module with require()
local avro = require('avro_schema')

-- create models
local ok_m, pokemon = avro.create(schema.pokemon)
local ok_p, player = avro.create(schema.player)
if ok_m and ok_p then
    -- compile models
    local ok_cm, compiled_pokemon = avro.compile(pokemon)
    local ok_cp, compiled_player = avro.compile(player)
    if ok_cm and ok_cp then
        -- start the game
        <...>
    else
        log.error('Schema compilation failed')
    end
else
    log.info('Schema creation failed')
end
return false

As for the map entity, it would be an overkill to introduce a schema for it, because we have only one map in the game, it has very few fields, and – which is most important – we use the map only inside our logic, never exposing it to external users.

../../../../_images/aster1.svg

Next, we need methods to implement the game logic. To simulate object-oriented programming in our Lua code, let’s store all Lua functions and shared variables in a single local variable (let’s name it as game). This will allow us to address functions or variables from within our module as self.func_name or self.var_name. Like this:

local game = {
    -- a local variable
    num_players = 0,

    -- a method that prints a local variable
    hello = function(self)
      print('Hello! Your player number is ' .. self.num_players .. '.')
    end,

    -- a method that calls another method and returns a local variable
    sign_in = function(self)
      self.num_players = self.num_players + 1
      self:hello()
      return self.num_players
    end
}

In OOP terms, we can now regard local variables inside game as object fields, and local functions as object methods.

Примечание

In this manual, Lua examples use local variables. Use global variables with caution, since the module’s users may be unaware of them.

To enable/disable the use of undeclared global variables in your Lua code, use Tarantool’s strict module.

So, our game module will have the following methods:

Besides, it would be convenient to have methods for working with Tarantool storage. For example:

We’ll need these two methods primarily when initializing our game, but we can also call them later, for example to test our code.

Bootstrapping a database

Let’s discuss game initialization. In start() method, we need to populate Tarantool spaces with pokémon data. Why not keep all game data in memory? Why use a database? The answer is: persistence. Without a database, we risk losing data on power outage, for example. But if we store our data in an in-memory database, Tarantool takes care to persist it on disk whenever it’s changed. This gives us one more benefit: quick startup in case of failure. Tarantool has a smart algorithm that quickly loads all data from disk into memory on startup, so the warm-up takes little time.

We’ll be using functions from Tarantool built-in box module:

Notice the parts = argument in the index specification. The pokémon ID is the first field in a Tarantool tuple since it’s the first member of the respective Avro type. So does the pokémon status. The actual JSON document may have ID or status fields at any position of the JSON map.

The implementation of start() method looks like this:

-- create game object
start = function(self)
    -- create spaces and indexes
    box.once('init', function()
        box.schema.create_space('pokemons')
        box.space.pokemons:create_index(
            "primary", {type = 'hash', parts = {1, 'unsigned'}}
        )
        box.space.pokemons:create_index(
            "status", {type = "tree", parts = {2, 'str'}}
        )
    end)

    -- create models
    local ok_m, pokemon = avro.create(schema.pokemon)
    local ok_p, player = avro.create(schema.player)
    if ok_m and ok_p then
        -- compile models
        local ok_cm, compiled_pokemon = avro.compile(pokemon)
        local ok_cp, compiled_player = avro.compile(player)
        if ok_cm and ok_cp then
            -- start the game
            <...>
        else
            log.error('Schema compilation failed')
        end
    else
        log.info('Schema creation failed')
    end
    return false
end

GIS

Now let’s discuss catch(), which is the main method in our gaming logic.

Here we receive the player’s coordinates and the target pokémon’s ID number, and we need to answer whether the player has actually caught the pokémon or not (remember that each pokémon has a chance to escape).

First thing, we validate the received player data against its Avro schema. And we check whether such a pokémon exists in our database and is displayed on the map (the pokémon must have the active status):

catch = function(self, pokemon_id, player)
    -- check player data
    local ok, tuple = self.player_model.flatten(player)
    if not ok then
        return false
    end
    -- get pokemon data
    local p_tuple = box.space.pokemons:get(pokemon_id)
    if p_tuple == nil then
        return false
    end
    local ok, pokemon = self.pokemon_model.unflatten(p_tuple)
    if not ok then
        return false
    end
    if pokemon.status ~= self.state.ACTIVE then
        return false
    end
    -- more catch logic to follow
    <...>
end

Next, we calculate the answer: caught or not.

To work with geographical coordinates, we use Tarantool gis module.

To keep things simple, we don’t load any specific map, assuming that we deal with a world map. And we do not validate incoming coordinates, assuming again that all received locations are within the planet Earth.

We use two geo-specific variables:

Both these systems are listed in the EPSG Geodetic Parameter Registry, where each system has a unique number. In our code, we assign these listing numbers to respective variables:

wgs84 = 4326,
nationalmap = 2163,

For our game logic, we need one more variable, catch_distance, which defines how close a player must get to a pokémon before trying to catch it. Let’s set the distance to 100 meters.

catch_distance = 100,

Now we’re ready to calculate the answer. We need to project the current location of both player (p_pos) and pokémon (m_pos) on the map, check whether the player is close enough to the pokémon (using catch_distance), and calculate whether the player has caught the pokémon (here we generate some random value and let the pokémon escape if the random value happens to be less than 100 minus pokémon’s chance value):

-- project locations
local m_pos = gis.Point(
    {pokemon.location.x, pokemon.location.y}, self.wgs84
):transform(self.nationalmap)
local p_pos = gis.Point(
    {player.location.x, player.location.y}, self.wgs84
):transform(self.nationalmap)

-- check catch distance condition
if p_pos:distance(m_pos) > self.catch_distance then
    return false
end
-- try to catch pokemon
local caught = math.random(100) >= 100 - pokemon.chance
if caught then
    -- update and notify on success
    box.space.pokemons:update(
        pokemon_id, {{'=', self.STATUS, self.state.CAUGHT}}
    )
    self:notify(player, pokemon)
end
return caught

Index iterators

By our gameplay, all caught pokémons are returned back to the map. We do this for all pokémons on the map every 60 seconds using respawn() method. We iterate through pokémons by status using Tarantool index iterator function index_object:pairs() and reset the statuses of all «caught» pokémons back to «active» using box.space.pokemons:update().

respawn = function(self)
    fiber.name('Respawn fiber')
    for _, tuple in box.space.pokemons.index.status:pairs(
           self.state.CAUGHT) do
        box.space.pokemons:update(
            tuple[self.ID],
            {{'=', self.STATUS, self.state.ACTIVE}}
        )
    end
 end

For readability, we introduce named fields:

ID = 1, STATUS = 2,

The complete implementation of start() now looks like this:

-- create game object
start = function(self)
    -- create spaces and indexes
    box.once('init', function()
       box.schema.create_space('pokemons')
       box.space.pokemons:create_index(
           "primary", {type = 'hash', parts = {1, 'unsigned'}}
       )
       box.space.pokemons:create_index(
           "status", {type = "tree", parts = {2, 'str'}}
       )
    end)

    -- create models
    local ok_m, pokemon = avro.create(schema.pokemon)
    local ok_p, player = avro.create(schema.player)
    if ok_m and ok_p then
        -- compile models
        local ok_cm, compiled_pokemon = avro.compile(pokemon)
        local ok_cp, compiled_player = avro.compile(player)
        if ok_cm and ok_cp then
            -- start the game
            self.pokemon_model = compiled_pokemon
            self.player_model = compiled_player
            self.respawn()
            log.info('Started')
            return true
         else
            log.error('Schema compilation failed')
         end
    else
        log.info('Schema creation failed')
    end
    return false
end

Fibers, yields and cooperative multitasking

But wait! If we launch it as shown above – self.respawn() – the function will be executed only once, just like all the other methods. But we need to execute respawn() every 60 seconds. Creating a fiber is the Tarantool way of making application logic work in the background at all times.

A fiber is a set of instructions that are executed with cooperative multitasking: the instructions contain yield signals, upon which control is passed to another fiber.

Let’s launch respawn() in a fiber to make it work in the background all the time. To do so, we’ll need to amend respawn():

respawn = function(self)
    -- let's give our fiber a name;
    -- this will produce neat output in fiber.info()
    fiber.name('Respawn fiber')
    while true do
        for _, tuple in box.space.pokemons.index.status:pairs(
                self.state.CAUGHT) do
            box.space.pokemons:update(
                tuple[self.ID],
                {{'=', self.STATUS, self.state.ACTIVE}}
            )
        end
        fiber.sleep(self.respawn_time)
    end
end

and call it as a fiber in start():

start = function(self)
    -- create spaces and indexes
        <...>
    -- create models
        <...>
    -- compile models
        <...>
    -- start the game
       self.pokemon_model = compiled_pokemon
       self.player_model = compiled_player
       fiber.create(self.respawn, self)
       log.info('Started')
    -- errors if schema creation or compilation fails
       <...>
end

Logging

One more helpful function that we used in start() was log.infо() from Tarantool log module. We also need this function in notify() to add a record to the log file on every successful catch:

-- event notification
notify = function(self, player, pokemon)
    log.info("Player '%s' caught '%s'", player.name, pokemon.name)
end

We use default Tarantool log settings, so we’ll see the log output in console when we launch our application in script mode.

../../../../_images/aster1.svg

Great! We’ve discussed all programming practices used in our Lua module (see pokemon.lua).

Now let’s prepare the test environment. As planned, we write a Lua application (see game.lua) to initialize Tarantool’s database module, initialize our game, call the game loop and simulate a couple of player requests.

To launch our microservice, we put both the pokemon.lua module and the game.lua application in the current directory, install all external modules, and launch the Tarantool instance running our game.lua application (this example is for Ubuntu):

$ ls
game.lua  pokemon.lua
$ sudo apt-get install tarantool-gis
$ sudo apt-get install tarantool-avro-schema
$ tarantool game.lua

Tarantool starts and initializes the database. Then Tarantool executes the demo logic from game.lua: adds a pokémon named Pikachu (its chance to be caught is very high, 99.1), displays the current map (it contains one active pokémon, Pikachu) and processes catch requests from two players. Player1 is located just near the lonely Pikachu pokémon and Player2 is located far away from it. As expected, the catch results in this output are «true» for Player1 and «false» for Player2. Finally, Tarantool displays the current map which is empty, because Pikachu is caught and temporarily inactive:

$ tarantool game.lua
2017-01-09 20:19:24.605 [6282] main/101/game.lua C> version 1.7.3-43-gf5fa1e1
2017-01-09 20:19:24.605 [6282] main/101/game.lua C> log level 5
2017-01-09 20:19:24.605 [6282] main/101/game.lua I> mapping 1073741824 bytes for tuple arena...
2017-01-09 20:19:24.609 [6282] main/101/game.lua I> initializing an empty data directory
2017-01-09 20:19:24.634 [6282] snapshot/101/main I> saving snapshot `./00000000000000000000.snap.inprogress'
2017-01-09 20:19:24.635 [6282] snapshot/101/main I> done
2017-01-09 20:19:24.641 [6282] main/101/game.lua I> ready to accept requests
2017-01-09 20:19:24.786 [6282] main/101/game.lua I> Started
---
- {'id': 1, 'status': 'active', 'location': {'y': 2, 'x': 1}, 'name': 'Pikachu', 'chance': 99.1}
...

2017-01-09 20:19:24.789 [6282] main/101/game.lua I> Player 'Player1' caught 'Pikachu'
true
false
--- []
...

2017-01-09 20:19:24.789 [6282] main C> entering the event loop

nginx

In the real life, this microservice would work over HTTP. Let’s add nginx web server to our environment and make a similar demo. But how do we make Tarantool methods callable via REST API? We use nginx with Tarantool nginx upstream module and create one more Lua script (app.lua) that exports three of our game methods – add_pokemon(), map() and catch() – as REST endpoints of the nginx upstream module:

local game = require('pokemon')
box.cfg{listen=3301}
game:start()

-- add, map and catch functions exposed to REST API
function add(request, pokemon)
    return {
        result=game:add_pokemon(pokemon)
    }
end

function map(request)
    return {
        map=game:map()
    }
end

function catch(request, pid, player)
    local id = tonumber(pid)
    if id == nil then
        return {result=false}
    end
    return {
        result=game:catch(id, player)
    }
end

An easy way to configure and launch nginx would be to create a Docker container based on a Docker image with nginx and the upstream module already installed (see http/Dockerfile). We take a standard nginx.conf, where we define an upstream with our Tarantool backend running (this is another Docker container, see details below):

upstream tnt {
      server pserver:3301 max_fails=1 fail_timeout=60s;
      keepalive 250000;
}

and add some Tarantool-specific parameters (see descriptions in the upstream module’s README file):

server {
  server_name tnt_test;

  listen 80 default deferred reuseport so_keepalive=on backlog=65535;

  location = / {
      root /usr/local/nginx/html;
  }

  location /api {
    # answers check infinity timeout
    tnt_read_timeout 60m;
    if ( $request_method = GET ) {
       tnt_method "map";
    }
    tnt_http_rest_methods get;
    tnt_http_methods all;
    tnt_multireturn_skip_count 2;
    tnt_pure_result on;
    tnt_pass_http_request on parse_args;
    tnt_pass tnt;
  }
}

Likewise, we put Tarantool server and all our game logic in a second Docker container based on the official Tarantool 1.9 image (see src/Dockerfile) and set the container’s default command to tarantool app.lua. This is the backend.

Non-blocking IO

To test the REST API, we create a new script (client.lua), which is similar to our game.lua application, but makes HTTP POST and GET requests rather than calling Lua functions:

local http = require('curl').http()
local json = require('json')
local URI = os.getenv('SERVER_URI')
local fiber = require('fiber')

local player1 = {
    name="Player1",
    id=1,
    location = {
        x=1.0001,
        y=2.0003
    }
}
local player2 = {
    name="Player2",
    id=2,
    location = {
        x=30.123,
        y=40.456
    }
}

local pokemon = {
    name="Pikachu",
    chance=99.1,
    id=1,
    status="active",
    location = {
        x=1,
        y=2
    }
}

function request(method, body, id)
    local resp = http:request(
        method, URI, body
    )
    if id ~= nil then
        print(string.format('Player %d result: %s',
            id, resp.body))
    else
        print(resp.body)
    end
end

local players = {}
function catch(player)
    fiber.sleep(math.random(5))
    print('Catch pokemon by player ' .. tostring(player.id))
    request(
        'POST', '{"method": "catch",
        "params": [1, '..json.encode(player)..']}',
        tostring(player.id)
    )
    table.insert(players, player.id)
end

print('Create pokemon')
request('POST', '{"method": "add",
    "params": ['..json.encode(pokemon)..']}')
request('GET', '')

fiber.create(catch, player1)
fiber.create(catch, player2)

-- wait for players
while #players ~= 2 do
    fiber.sleep(0.001)
end

request('GET', '')
os.exit()

When you run this script, you’ll notice that both players have equal chances to make the first attempt at catching the pokémon. In a classical Lua script, a networked call blocks the script until it’s finished, so the first catch attempt can only be done by the player who entered the game first. In Tarantool, both players play concurrently, since all modules are integrated with Tarantool cooperative multitasking and use non-blocking I/O.

Indeed, when Player1 makes its first REST call, the script doesn’t block. The fiber running catch() function on behalf of Player1 issues a non-blocking call to the operating system and yields control to the next fiber, which happens to be the fiber of Player2. Player2’s fiber does the same. When the network response is received, Player1’s fiber is activated by Tarantool cooperative scheduler, and resumes its work. All Tarantool modules use non-blocking I/O and are integrated with Tarantool cooperative scheduler. For module developers, Tarantool provides an API.

For our HTTP test, we create a third container based on the official Tarantool 1.9 image (see client/Dockerfile) and set the container’s default command to tarantool client.lua.

../../../../_images/aster1.svg

To run this test locally, download our pokemon project from GitHub and say:

$ docker-compose build
$ docker-compose up

Docker Compose builds and runs all the three containers: pserver (Tarantool backend), phttp (nginx) and pclient (demo client). You can see log messages from all these containers in the console, pclient saying that it made an HTTP request to create a pokémon, made two catch requests, requested the map (empty since the pokémon is caught and temporarily inactive) and exited:

pclient_1  | Create pokemon
<...>
pclient_1  | {"result":true}
pclient_1  | {"map":[{"id":1,"status":"active","location":{"y":2,"x":1},"name":"Pikachu","chance":99.100000}]}
pclient_1  | Catch pokemon by player 2
pclient_1  | Catch pokemon by player 1
pclient_1  | Player 1 result: {"result":true}
pclient_1  | Player 2 result: {"result":false}
pclient_1  | {"map":[]}
pokemon_pclient_1 exited with code 0

Congratulations! Here’s the end point of our walk-through. As further reading, see more about installing and contributing a module.

See also reference on Tarantool modules and C API, and don’t miss our Lua cookbook recipes.

Практическое задание на C

Хранимые процедуры на языке C

Tarantool может вызывать код на языке C с помощью модулей, ffi или хранимых процедур на C. В данном практическом задании рассматривается только третий метод, хранимые процедуры на языке C. На самом деле, программы всегда представляют собой функции на языке C, но исторически сложилось так, что широко используется фраза «хранимая процедура».

Данное практическое задание могут выполнить те, у кого есть пакет программ для разработки Tarantool и компилятор языка программирования C. Оно состоит из пяти задач:

  1. easy.c – выводит «hello world»;
  2. harder.c – декодирует переданное значение параметра;
  3. hardest.c – использует API для языка C для вставки в базу данных;
  4. read.c – использует API для языка C для выборки из базы данных;
  5. write.c – использует API для языка C для замены в базе данных.

По окончании задания, вы увидите описанные здесь результаты и сможете самостоятельно написать хранимые процедуры.

Preparation

Проверьте наличие следующих элементов на компьютере:

  • Tarantool 2.1 or later
  • Компилятор GCC, подойдет любая современная версия
  • module.h и включенные в него файлы
  • msgpuck.h
  • libmsgpuck.a (только для некоторых последних версий msgpuck)

Файл module.h есть в системе, если Tarantool был установлен из исходных файлов. В противном случае, следует установить пакет Tarantool «developer». Например, на Ubuntu введите команду:

$ sudo apt-get install tarantool-dev

или на Fedora введите команду:

$ dnf -y install tarantool-devel

The msgpuck.h file will exist if Tarantool was installed from source. Otherwise the «msgpuck» package must be installed from https://github.com/tarantool/msgpuck.

Чтобы компилятор C увидел файлы module.h и msgpuck.h, путь к ним следует сохранить в переменной. Например, если адрес файла module.h – /usr/local/include/tarantool/module.h, а адрес файла msgpuck.h – /usr/local/include/msgpuck/msgpuck.h, введите команду:

$ export CPATH=/usr/local/include/tarantool:/usr/local/include/msgpuck

Статическая библиотека libmsgpuck.a нужна для версий msgpuck старше февраля 2017 года. Только в том случае, если встречаются проблемы соединения при использовании операторов GCC в примерах данного практического задания, в пути следует указывать libmsgpuck.a (libmsgpuck.a создан из исходных файлов загрузки msgpuck и Tarantool, поэтому его легко найти). Например, вместо «gcc -shared -o harder.so -fPIC harder.c» во втором примере ниже, необходимо ввести «gcc -shared -o harder.so -fPIC harder.c libmsgpuck.a».

Tarantool выполняет запросы в качестве клиента. Запустите Tarantool и введите эти запросы.

box.cfg{listen=3306}
box.schema.space.create('capi_test')
box.space.capi_test:create_index('primary')
net_box = require('net.box')
capi_connection = net_box:new(3306)

Проще говоря: создайте спейс под названием capi_test, и выполните соединение с одноименным capi_connection.

Не закрывайте клиент. Он понадобится для последующих запросов.

easy.c

Запустите еще один терминал. Измените директорию (cd), чтобы она совпадала с директорией, где запущен клиент.

Create a file. Name it easy.c. Put the following code in it:

#include "module.h"
int easy(box_function_ctx_t *ctx, const char *args, const char *args_end)
{
  printf("hello world\n");
  return 0;
}
int easy2(box_function_ctx_t *ctx, const char *args, const char *args_end)
{
  printf("hello world -- easy2\n");
  return 0;
}

Скомпилируйте программу, что создаст файл библиотеки под названием easy.so:

$ gcc -shared -o easy.so -fPIC easy.c

Теперь вернитесь в клиент и выполните следующие запросы:

box.schema.func.create('easy', {language = 'C'})
box.schema.user.grant('guest', 'execute', 'function', 'easy')
capi_connection:call('easy')

Если эти запросы вам незнакомы, перечитайте описание box.schema.func.create(), box.schema.user.grant() и conn:call().

Важна функция capi_connection:call('easy').

Во-первых, она ищет функцию easy, что должно быть легко, потому что по умолчанию Tarantool ищет в текущей директории файл под названием easy.so.

Во-вторых, она вызывает функцию easy. Поскольку функция easy() в easy.c начинается с printf("hello world\n"), слова «hello world» появятся на экране.

В-третьих, она проверяет, что вызов прошел успешно. Поскольку функция easy() в easy.c оканчивается на return 0, сообщение об ошибке отсутствует, и запрос выполнен.

Результат должен выглядеть следующим образом:

tarantool> capi_connection:call('easy')
hello world
---
- []
...

Теперь вызовем другую функцию в easy.c – easy2(). Она практически совпадает с функцией easy(), но есть небольшое отличие: если имя файла не совпадет с именем функции, нужно будет указать имя-файла.имя-функции.

box.schema.func.create('easy.easy2', {language = 'C'})
box.schema.user.grant('guest', 'execute', 'function', 'easy.easy2')
capi_connection:call('easy.easy2')

… и на этот раз результатом будет: «hello world – easy2».

Вывод: вызвать C-функцию легко.

harder.c

Вернитесь в терминал, где была создана программа easy.c.

Создайте файл. Назовите его harder.c. Запишите в него следующие 17 строк:

#include "module.h"
#include "msgpuck.h"
int harder(box_function_ctx_t *ctx, const char *args, const char *args_end)
{
  uint32_t arg_count = mp_decode_array(&args);
  printf("arg_count = %d\n", arg_count);
  uint32_t field_count = mp_decode_array(&args);
  printf("field_count = %d\n", field_count);
  uint32_t val;
  int i;
  for (i = 0; i < field_count; ++i)
  {
    val = mp_decode_uint(&args);
    printf("val=%d.\n", val);
  }
  return 0;
}

Скомпилируйте программу, что создаст файл библиотеки под названием harder.so:

$ gcc -shared -o harder.so -fPIC harder.c

Теперь вернитесь в клиент и выполните следующие запросы:

box.schema.func.create('harder', {language = 'C'})
box.schema.user.grant('guest', 'execute', 'function', 'harder')
passable_table = {}
table.insert(passable_table, 1)
table.insert(passable_table, 2)
table.insert(passable_table, 3)
capi_connection:call('harder', {passable_table})

На этот раз вызов передает Lua-таблицу (passable_table) в функцию harder(). Функция``harder()`` увидит это, как указано в параметре char *args.

At this point the harder() function will start using functions defined in msgpuck.h. The routines that begin with «mp» are msgpuck functions that handle data formatted according to the MsgPack specification. Passes and returns are always done with this format so one must become acquainted with msgpuck to become proficient with the C API.

Однако, пока достаточно понимать, что функция mp_decode_array() возвращает количество элементов в массиве, а функция mp_decode_uint возвращает целое число без знака из args. Есть также побочный эффект: по окончании декодирования args изменился и теперь указывает на следующий элемент.

Таким образом, первой будет отображена строка «arg_count = 1», поскольку был передан только один элемент: passable_table.
Второй будет отображена строка «field_count = 3», потому что в таблице находятся три элемента.
Следующие три строки будут «1», «2» и «3», потому что это значения элементов в таблице.

Теперь вывод на экране выглядит следующим образом:

tarantool> capi_connection:call('harder', passable_table)
arg_count = 1
field_count = 3
val=1.
val=2.
val=3.
---
- []
...

Вывод: на первый взгляд, декодирование значений параметров, переданных в C-функцию непросто, но существуют документированные процедуры для этих целей, и их не так много.

hardest.c

Вернитесь в терминал, где были созданы программы easy.c и harder.c.

Создайте файл. Назовите его `hardest.c. Запишите в него следующие 13 строк:

#include "module.h"
#include "msgpuck.h"
int hardest(box_function_ctx_t *ctx, const char *args, const char *args_end)
{
  uint32_t space_id = box_space_id_by_name("capi_test", strlen("capi_test"));
  char tuple[1024]; /* Must be big enough for mp_encode results */
  char *tuple_pointer = tuple;
  tuple_pointer = mp_encode_array(tuple_pointer, 2);
  tuple_pointer = mp_encode_uint(tuple_pointer, 10000);
  tuple_pointer = mp_encode_str(tuple_pointer, "String 2", 8);
  int n = box_insert(space_id, tuple, tuple_pointer, NULL);
  return n;
}

Скомпилируйте программу, что создаст файл библиотеки под названием hardest.so:

$ gcc -shared -o hardest.so -fPIC hardest.c

Теперь вернитесь в клиент и выполните следующие запросы:

box.schema.func.create('hardest', {language = "C"})
box.schema.user.grant('guest', 'execute', 'function', 'hardest')
box.schema.user.grant('guest', 'read,write', 'space', 'capi_test')
capi_connection:call('hardest')

На этот раз C-функция выполняет три действия:

  1. найдет числовой идентификатор спейса capi_test путем вызова box_space_id_by_name();
  2. форматирует кортеж, используя другие функции msgpuck.h;
  3. вставит кортеж с помощью box_insert().

Предупреждение

char tuple[1024]; используется здесь просто в качестве быстрого способа ввода команды «выделить байтов с запасом». В серьезных программах разработчику следует обратить внимание на то, чтобы выделить достаточно места, которое будут использовать процедуры mp_encode.

Затем всё еще в клиенте выполните следующий запрос:

box.space.capi_test:select()

Результат должен выглядеть следующим образом:

tarantool> box.space.capi_test:select()
---
- - [10000, 'String 2']
...

Это доказывает, что функция hardest() была успешно выполнена, но откуда взялись box_space_id_by_name() и box_insert()? Ответ: API для языка C.

read.c

Вернитесь в терминал, где были созданы программы easy.c, harder.c и hardest.c.

Создайте файл. Назовите его read.c. Запишите в него следующие 43 строки:

#include "module.h"
#include <msgpuck.h>
int read(box_function_ctx_t *ctx, const char *args, const char *args_end)
{
  char tuple_buf[1024];      /* where the raw MsgPack tuple will be stored */
  uint32_t space_id = box_space_id_by_name("capi_test", strlen("capi_test"));
  uint32_t index_id = 0;     /* The number of the space's first index */
  uint32_t key = 10000;      /* The key value that box_insert() used */
  mp_encode_array(tuple_buf, 0); /* clear */
  box_tuple_format_t *fmt = box_tuple_format_default();
  box_tuple_t *tuple = NULL;
  char key_buf[16];          /* Pass key_buf = encoded key = 1000 */
  char *key_end = key_buf;
  key_end = mp_encode_array(key_end, 1);
  key_end = mp_encode_uint(key_end, key);
  assert(key_end <= key_buf + sizeof(key_buf));
  /* Get the tuple. There's no box_select() but there's this. */
  int r = box_index_get(space_id, index_id, key_buf, key_end, &tuple);
  assert(r == 0);
  assert(tuple != NULL);
  /* Get each field of the tuple + display what you get. */
  int field_no;             /* The first field number is 0. */
  for (field_no = 0; field_no < 2; ++field_no)
  {
    const char *field = box_tuple_field(tuple, field_no);
    assert(field != NULL);
    assert(mp_typeof(*field) == MP_STR || mp_typeof(*field) == MP_UINT);
    if (mp_typeof(*field) == MP_UINT)
    {
      uint32_t uint_value = mp_decode_uint(&field);
      printf("uint value=%u.\n", uint_value);
    }
    else /* if (mp_typeof(*field) == MP_STR) */
    {
      const char *str_value;
      uint32_t str_value_length;
      str_value = mp_decode_str(&field, &str_value_length);
      printf("string value=%.*s.\n", str_value_length, str_value);
    }
  }
  return 0;
}

Скомпилируйте программу, что создаст файл библиотеки под названием read.so:

$ gcc -shared -o read.so -fPIC read.c

Теперь вернитесь в клиент и выполните следующие запросы:

box.schema.func.create('read', {language = "C"})
box.schema.user.grant('guest', 'execute', 'function', 'read')
box.schema.user.grant('guest', 'read,write', 'space', 'capi_test')
capi_connection:call('read')

На этот раз C-функция выполняет четыре действия:

  1. снова найдет числовой идентификатор спейса capi_test путем вызова box_space_id_by_name();
  2. форматирует ключ поиска = 10 000, используя другие функции msgpuck.h;
  3. получает кортеж с помощью box_index_get();
  4. проходит по полям каждого кортежа с помощью box_tuple_get(). а затем декодирует каждое поле в зависимости от его типа. В данном случае, поскольку мы получаем кортеж, который сами вставили с помощью hardest.c, мы знаем заранее, что его тип будет MP_UINT или MP_STR. Однако, весьма часто здесь употребляется оператор выбора case с одной опцией для каждого возможного типа.

В результате вызова capi_connection:call('read') должны получить:

tarantool> capi_connection:call('read')
uint value=10000.
string value=String 2.
---
- []
...

Это доказывает, что функция read() была успешно выполнена. И снова важные функции, которые начинаются с box – box_index_get() и box_tuple_field() – пришли из API для языка C.

write.c

Вернитесь в терминал, где были созданы программы easy.c, harder.c, hardest.c и read.c.

Создайте файл. Назовите его write.c. Запишите в него следующие 24 строки:

#include "module.h"
#include <msgpuck.h>
int write(box_function_ctx_t *ctx, const char *args, const char *args_end)
{
  static const char *space = "capi_test";
  char tuple_buf[1024]; /* Должен быть достаточно большим, чтобы вместить результат mp_encode */
  uint32_t space_id = box_space_id_by_name(space, strlen(space));
  if (space_id == BOX_ID_NIL) {
    return box_error_set(__FILE__, __LINE__, ER_PROC_C,
    "Can't find space %s", "capi_test");
  }
  char *tuple_end = tuple_buf;
  tuple_end = mp_encode_array(tuple_end, 2);
  tuple_end = mp_encode_uint(tuple_end, 1);
  tuple_end = mp_encode_uint(tuple_end, 22);
  box_txn_begin();
  if (box_replace(space_id, tuple_buf, tuple_end, NULL) != 0)
    return -1;
  box_txn_commit();
  fiber_sleep(0.001);
  struct tuple *tuple = box_tuple_new(box_tuple_format_default(),
                                      tuple_buf, tuple_end);
  return box_return_tuple(ctx, tuple);
}

Скомпилируйте программу, что создаст файл библиотеки под названием write.so:

$ gcc -shared -o write.so -fPIC write.c

Теперь вернитесь в клиент и выполните следующие запросы:

box.schema.func.create('write', {language = "C"})
box.schema.user.grant('guest', 'execute', 'function', 'write')
box.schema.user.grant('guest', 'read,write', 'space', 'capi_test')
capi_connection:call('write')

На этот раз C-функция выполняет шесть действий:

  1. снова найдет числовой идентификатор спейса capi_test путем вызова box_space_id_by_name();
  2. создает новый кортеж;
  3. начинает транзакцию;
  4. заменяет кортеж в box.space.capi_test
  5. заканчивает транзакцию;
  6. последняя строка заменяет цикл read.c – вместо получения и вывода каждого поля, использует функцию box_return_tuple(...) для возврата всего кортежа вызывающему клиенту, чтобы вывести его на экран.

В результате вызова capi_connection:call('write') должны получить:

tarantool> capi_connection:call('write')
---
- [[1, 22]]
...

Это доказывает, что функция write() была успешно выполнена. И снова важные функции, которые начинаются с box – box_txn_begin(), box_txn_commit() и box_return_tuple() – пришли из API для языка C.

Вывод: длинное описание всего API для языка C необходимо в силу весомых причин. Все функции можно вызвать из C-функций, которые вызываются из Lua. Таким образом, хранимые процедуры на языке C получают полный доступ к базе данных.

Cleaning up

  • Удалите все кортежи с функцией с помощью box.schema.func.drop().
  • Удалите спейс capi_test с помощью box.schema.capi_test:drop().
  • Удалите файлы с разрешением .c и .so, созданные для данного практического задания.

An example in the test suite

Скачайте исходный код Tarantool. Откройте поддиректорию test/box. Проверьте наличие файла под названием tuple_bench.test.lua и еще одного файла под названием tuple_bench.c. Изучите Lua-файл на предмет вызова функции в C-файле с использованием методов, описанных в данном практическом задании.

Вывод: некоторые тесты из стандартного набора используют хранимые процедуры на языке C, а они должны работать, поскольку мы не можем выпустить Tarantool, если он не прошел тестирование.

Разработка с IDE

Для разработки и отладки Lua-приложений для Tarantool можно использовать IntelliJ IDEA в качестве интегрированной среды разработки (IDE).

  1. Загрузите и установите IDE с официального сайта.

    JetBrains предоставляет специализированные версии для разных языков программирования: IntelliJ IDEA (Java), PHPStorm (PHP), PyCharm (Python), RubyMine (Ruby), CLion (C/C++), WebStorm (Web) и другие. Поэтому загрузите версию, которая подходит предпочитаемому языку.

    Для всех версий поддерживается интеграция с Tarantool.

  2. Настройте IDE:

    1. Запустите IntelliJ IDEA.

    2. Нажмите кнопку Configure и выберите Plugins.

      ../../../_images/ide_1.png

    3. Нажмите Browse repositories.

      ../../../_images/ide_2.png

    4. Установите плагин EmmyLua.

      Примечание

      Не путайте с плагином Lua, у которого меньше возможностей, чем у EmmyLua.

      ../../../_images/ide_3.png

    5. Перезапустите IntelliJ IDEA.

    6. Нажмите Configure, выберите Project Defaults, а затем Run Configurations.

      ../../../_images/ide_4.png

    7. Найдите Lua Application в боковой панели слева.

    8. В Program введите путь к установленному бинарному файлу tarantool.

      По умолчанию, это tarantool или /usr/bin/tarantool на большинстве платформ.

      Если вы установили tarantool из источников в другую директорию, укажите здесь правильный путь.

      ../../../_images/ide_5.png

      Теперь IntelliJ IDEA можно использовать с Tarantool.

  3. Создайте новый проект на Lua.

    ../../../_images/ide_6.png

  4. Добавьте новый Lua-файл, например, init.lua.

    ../../../_images/ide_7.png

  5. Разработайте код, сохраните файл.

  6. Чтобы запустить приложение, нажмите Run -> Run в основном меню и выберите исходный файл из списка.

    ../../../_images/ide_8.png

    Или нажмите Run -> Debug для начала отладки.

    Примечание

    Чтобы использовать Lua-отладчик, обновите Tarantool до версии 1.7.5-29-gbb6170e4b или более поздней версии.

    ../../../_images/ide_9.png

Tooling

This section describes the tools that enable developers and administrators to work with Tarantool.

tt CLI utility

tt is a utility that provides a unified command-line interface for managing Tarantool-based applications. It covers a wide range of tasks – from installing a specific Tarantool version to managing remote instances and developing applications.

tt is developed in its own GitHub repository. Here you can find its source code, changelog, and releases information. For a complete list of releases, see the Releases section on GitHub.

There is also the Enterprise version of tt available in a Tarantool Enterprise Edition’s release package. The Enterprise version provides additional features, for example, importing and exporting data.

This section provides instructions on tt installation and configuration, concept explanation, and the tt command reference.

tt environments

The key aspect of the tt usage is an environment. A tt environment is a directory that includes a tt configuration, Tarantool installations, application files, and other resources. If you’re familiar with Python virtual environments, you can think of tt environments as their analog.

tt environments enable independent management of multiple Tarantool applications, each running on its own Tarantool version and configuration, on a single host in an isolated manner.

To create a tt environment in a directory, run tt init in it.

Multi-instance applications

tt supports Tarantool applications that run on multiple instances. For example, you can write an application that includes different source files for storage and router instances. With tt, you can start and stop them in a single call, or manage each instance independently.

Learn more about working with multi-instance applications in Multi-instance applications.

Replacement for tarantooctl and Cartridge CLI

A multi-purpose tool for working with Tarantool from the command line, tt has come to replace the deprecated utilities tarantoolctl and Cartridge CLI command-line utilities. The instructions on migration to tt are provided in Migration from tarantoolctl to tt.

Installation

To install the tt command-line utility, use a package manager – Yum or APT on Linux, or Homebrew on macOS. If you need a specific build, you can build tt from sources.

Примечание

A Tarantool Enterprise Edition’s release package includes the tt utility extended with additional features like importing and exporting data.

Using Linux package managers

On Linux systems, you can install tt with yum or apt package managers from the tarantool/modules repository. Learn how to add this repository.

The installation command looks like this:

Using Homebrew on macOS

On macOS, use Homebrew to install tt:

$ brew install tt

Building from sources

To build tt from sources:

  1. Install third-party software required for building tt:

  1. Clone the tarantool/tt repository:

    git clone https://github.com/tarantool/tt --recursive

  2. Go to the tt directory:

    cd tt

  3. (Optional) Checkout a release tag to build a specific version:

    git checkout tags/v1.0.0

  4. Build tt using mage:

    mage build

tt will appear in the current directory.

Enabling shell completion

To enable the completion for tt commands, run the following command specifying the shell (bash or zsh):

. <(tt completion bash)

Configuration

Configuration file

The key artifact that defines the tt environment and various aspects of its execution is its configuration file. You can generate it with a tt init call. In the default launch mode, the file is generated in the current directory, making it the environment root.

Name and location

By default, the configuration file is called tt.yaml and located in the tt environment root directory. It depends on the launch mode.

It is also possible to pass the configuration file name and location explicitly using the following ways:

  1. -c/--cfg global option
  2. TT_CLI_CFG environment variable.

The TT_CLI_CFG variable has a lower priority than the --cfg option.

Structure

The tt configuration file is a YAML file with the following structure:

env:
  instances_enabled: path/to/available/applications
  bin_dir: path/to/bin_dir
  inc_dir: path/to/inc_dir
  restart_on_failure: bool
  tarantoolctl_layout: bool
modules:
  directory: path/to/modules/dir
app:
  run_dir: path/to/run_dir
  log_dir: path/to/log_dir
  wal_dir: path/to/wal_dir
  vinyl_dir: path/to/vinyl_dir
  memtx_dir: path/to/memtx_dir
repo:
  rocks: path/to/rocks
  distfiles: path/to/install
ee:
  credential_path: path/to/file
templates:
  - path: path/to/app/templates1
  - path: path/to/app/templates2

Примечание

The tt configuration format and application layout have been changed in version 2.0. Learn how to upgrade from earlier versions in Migrating from tt 1.* to 2.0 or later.

env section

Примечание

The paths specified in env.* parameters are relative to the current tt environment’s root.

  • instances_enabled – the directory where instances are stored. Default: instances.enabled.

  • bin_dir – the directory where binary files are stored. Default: bin.

  • inc_dir – the base directory for storing header files. They will be placed in the include subdirectory inside the specified directory. Default: include.

    Примечание

    The header files directory path can also be passed using the TT_CLI_TARANTOOL_PREFIX environment variable. If it is set, tt rocks and tt build commands use the include/tarantool directory inside TT_CLI_TARANTOOL_PREFIX as the header files directory.

  • restart_on_failure – restart the instance on failure: true or false. Default: false.

  • tarantoolctl_layout – use a layout compatible with the deprecated tarantoolctl utility for artifact files: control sockets, .pid files, log files. Default: false.

modules section

app section

Примечание

The paths specified in app.*_dir parameters are relative to the application location inside the instances.enabled directory specified in the env configuration section. For example, the default location of the myapp application’s logs is instances.enabled/myapp/var/log. Inside this location, tt creates separate directories for each application instance that runs in the current environment.

  • run_dir– the directory for instance runtime artifacts, such as console sockets or PID files. Default: var/run.
  • log_dir – the directory where log files are stored. Default: var/log.
  • wal_dir – the directory where write-ahead log (.xlog) files are stored. Default: var/lib.
  • memtx_dir – the directory where memtx stores snapshot (.snap) files. Default: var/lib.
  • vinyl_dir – the directory where vinyl files or subdirectories are stored. Default: var/lib.

repo section

  • rocks – the directory where rocks files are stored.

    Примечание

    The rocks directory path can be passed in the TT_CLI_REPO_ROCKS environment variable instead. The variable is also used if the directory specified in repo.rocks does not include a repository manifest.

  • distfiles – the directory where installation files are stored.

ee section

  • credential_path – a path to the file with credentials used for downloading Tarantool Enterprise Edition (Tarantool customer zone credentials). The file should contain a username and a password, each on a separate line. Find an example in the tt install command reference.

    Примечание

    The customer zone credentials can also be passed in the TT_CLI_EE_USERNAME and TT_CLI_EE_PASSWORD environment variables.

templates section

  • path – a path to application templates used for creating applications with tt create. May be specified more than once.

Launch modes

tt launch mode defines its working directory and the way it searches for the configuration file. There are three launch modes:

Default launch

Global option: none

Configuration file: searched from the current directory to the root. Taken from /etc/tarantool if the file is not found.

Working directory: The directory where the configuration file is found.

System launch

Global option: --system or -S

Configuration file: Taken from /etc/tarantool.

Working directory: Current directory.

Local launch

Global option: --local=DIRECTORY or -L=DIRECTORY

Configuration file: Searched from the specified directory to the root. Taken from /etc/tarantool if the file is not found.

Working directory: The specified directory. If tarantool or tt executable files are found in the working directory, they will be used.

Migrating from tt 1.* to 2.0 or later

The tt configuration and application layout were changed in version 2.0. If you are using tt 1.*, complete the following steps to migrate to tt 2.0 or later:

  1. Update the tt configuration file. In tt 2.0, the following changes were made to the configuration file:

    • The root section tt was removed. Its child sections – app, repo, modules, and other – have been moved to the top level.
    • Environment configuration parameters were moved from the app section to the new section env. These parameters are instances.enabled, bin_dir, inc_dir, and restart_on_failure.
    • The paths in the app section are now relative to the app directory in instances.enabled instead of the environment root.

    You can use tt init to generate a configuration file with the new structure and default parameter values.

  2. Move application artifacts. With tt 1.*, application artifacts (logs, snapshots, pid, and other files) were created in the var directory inside the environment root. Starting from tt 2.0, these artifacts are created in the var directory inside the application directory, which is instances.enabled/<app-name>. This is how an application directory looks:

    instances.enabled/app/
├── init.lua
├── instances.yml
└── var
    ├── lib
    │   ├── instance1
    │   └── instance2
    ├── log
    │   ├── instance1
    │   └── instance2
    └── run
        ├── instance1
        └── instance2

    To continue using existing application artifacts after migration from tt 1.*:

    1. Create the var directory inside the application directory.
    2. Create the lib, log, and run directories inside var.
    3. Move directories with instance artifacts from the old var directory to the new var directories in applications“ directories.

  3. Move the files accessed from the application code. The working directory of instance processes was changed from the tt working directory to the application directory inside instances.enabled. If the application accesses files using relative paths, move the files accordingly or adjust the application code.

Global options

Важно

Global options of tt must be passed before its commands and other options. For example:

$ tt --cfg tt-conf.yaml start app

tt has the following global options:

-c=file, --cfg=file,

Path to the configuration file.

Alternatively, this path can be passed in the TT_CLI_CFG environment variable.

-h, --help

Display help.

--integrity-check PUBLIC_KEY

Enterprise Edition

This option is supported by the Enterprise Edition only.

Perform an integrity check using the specified public key before executing the operation. Learn more in Integrity check.

-I, --internal

Force the use of an internal module even if there is an external module with the same name.

-L=DIRECTORY, --local=DIRECTORY

Use the tt environment from the specified directory. Learn more about the local launch mode.

-s, --self

Use the current tt version instead of executing the one located in the bin_dir directory.

-S, --system

Use the tt environment installed in the system. Learn more about the system launch mode.

-V, --verbose

Display detailed processing information (verbose mode).

Developing applications

This section describes tt capabilities related to developing cluster applications.

Application environment

This section provides a high-level overview on how to prepare a Tarantool application for deployment and how the application’s environment and layout might look. This information is helpful for understanding how to administer Tarantool instances using tt CLI in both development and production environments.

The main steps of creating and preparing the application for deployment are:

  1. Initializing a local environment.
  2. Creating and developing an application.
  3. Packaging the application.

In this section, a sharded_cluster_crud application is used as an example. This cluster includes 5 instances: one router and 4 storages, which constitute two replica sets.

Cluster topology

Initializing a local environment

Before creating an application, you need to set up a local environment for tt:

  1. Create a home directory for the environment.

  2. Run tt init in this directory:

    ~/myapp$ tt init
   • Environment config is written to 'tt.yaml'

This command creates a default tt configuration file tt.yaml for a local environment and the directories for applications, control sockets, logs, and other artifacts:

~/myapp$ ls
bin  distfiles  include  instances.enabled  modules  templates  tt.yaml

Find detailed information about the tt configuration parameters and launch modes on the tt configuration page.

Creating and developing an application

You can create an application in two ways:

In this example, the application’s layout is prepared manually and looks as follows.

~/myapp$ tree
.
├── bin
├── distfiles
├── include
├── instances.enabled
│   └── sharded_cluster_crud
│       ├── config.yaml
│       ├── instances.yaml
│       ├── router.lua
│       ├── sharded_cluster_crud-scm-1.rockspec
│       └── storage.lua
├── modules
├── templates
└── tt.yaml

The sharded_cluster_crud directory contains the following files:

You can find the full example here: sharded_cluster_crud.

Packaging the application

To package the ready application, use the tt pack command. This command can create an installable DEB/RPM package or generate .tgz archive.

The structure below reflects the content of the packed .tgz archive for the sharded_cluster_crud application:

~/myapp$ tree -a
.
├── bin
│   ├── tarantool
│   └── tt
├── instances.enabled
│   └── sharded_cluster_crud -> ../sharded_cluster_crud
├── sharded_cluster_crud
│   ├── .rocks
│   │   └── share
│   │       └── ...
│   ├── config.yaml
│   ├── instances.yaml
│   ├── router.lua
│   └── storage.lua
└── tt.yaml

The application’s layout looks similar to the one defined when developing the application with some differences:

Примечание

In DEB/PRM packages generated by tt pack, there are also .service unit files for each packaged application.

Deploying the application

Instances to run

When deploying a distributed cluster application from a .tar.gz archive, you can define instances to run on each machine by changing the content of the instances.yaml file.

  • On the developer’s machine, this file might include all the instances defined in the cluster configuration.

    Cluster topology

    instances.yaml:

    storage-a-001:
storage-a-002:
storage-b-001:
storage-b-002:
router-a-001:

  • In the production environment, this file includes instances to run on the specific machine.

    Cluster topology

    instances.yaml (Server-001):

    router-a-001:

    instances.yaml (Server-002):

    storage-a-001:
storage-b-001:

    instances.yaml (Server-003):

    storage-a-002:
storage-b-002:

The Starting and stopping instances section describes how to start and stop Tarantool instances.

DEB and RPM packages

Tarantool applications installed from DEB and RPM packages built with tt pack can run as systemd services. They run on behalf of the tarantool system user. It is created automatically during the package installation.

By default, the application artifacts are placed in the following directories:

  • /var/lib/tarantool/sys_env – application data
  • /var/log/tarantool/sys_env – logs
  • /var/run/tarantool/sys_env – runtime artifacts

If you want to change these directories, make sure that the tarantool user has enough permissions on the directories you use.

Starting and stopping instances

This section describes how to manage instances in a Tarantool cluster using the tt utility. A cluster can include multiple instances that run different code. A typical example is a cluster application that includes router and storage instances. Particularly, you can perform the following actions:

To get more context on how the application’s environment might look, refer to Application environment.

Примечание

In this section, a sharded_cluster_crud application is used to demonstrate how to start, stop, and manage instances in a cluster.

Starting Tarantool instances

To start Tarantool instances use the tt start command:

$ tt start sharded_cluster_crud
   • Starting an instance [sharded_cluster_crud:storage-a-001]...
   • Starting an instance [sharded_cluster_crud:storage-a-002]...
   • Starting an instance [sharded_cluster_crud:storage-b-001]...
   • Starting an instance [sharded_cluster_crud:storage-b-002]...
   • Starting an instance [sharded_cluster_crud:router-a-001]...

After the cluster has started and worked for some time, you can find its artifacts in the directories specified in the tt configuration. These are the default locations in the local launch mode:

In the system launch mode, artifacts are created in these locations:

Basic instance management

Most of the commands described in this section can be called with or without an instance name. Without the instance name, they are executed for all instances defined in instances.yaml.

Checking an instance’s status

To check the status of instances, execute tt status:

$ tt status sharded_cluster_crud
INSTANCE                          STATUS      PID   MODE
sharded_cluster_crud:storage-a-001     RUNNING     2023  RW
sharded_cluster_crud:storage-a-002     RUNNING     2026  RO
sharded_cluster_crud:storage-b-001     RUNNING     2020  RW
sharded_cluster_crud:storage-b-002     RUNNING     2021  RO
sharded_cluster_crud:router-a-001      RUNNING     2022  RW

To check the status of a specific instance, you need to specify its name:

$ tt status sharded_cluster_crud:storage-a-001
INSTANCE                          STATUS      PID   MODE
sharded_cluster_crud:storage-a-001     RUNNING     2023  RW

Connecting to an instance

To connect to the instance, use the tt connect command:

$ tt connect sharded_cluster_crud:storage-a-001
   • Connecting to the instance...
   • Connected to sharded_cluster_crud:storage-a-001

sharded_cluster_crud:storage-a-001>

In the instance’s console, you can execute commands provided by the box module. For example, box.info can be used to get various information about a running instance:

sharded_cluster_crud:storage-a-001> box.info.ro
---
- false
...

Restarting instances

To restart an instance, use tt restart:

$ tt restart sharded_cluster_crud:storage-a-002

After executing tt restart, you need to confirm this operation:

Confirm restart of 'sharded_cluster_crud:storage-a-002' [y/n]: y
   • The Instance sharded_cluster_crud:storage-a-002 (PID = 2026) has been terminated.
   • Starting an instance [sharded_cluster_crud:storage-a-002]...

Stopping instances

To stop the specific instance, use tt stop as follows:

$ tt stop sharded_cluster_crud:storage-a-002

You can also stop all the instances at once as follows:

$ tt stop sharded_cluster_crud
   • The Instance sharded_cluster_crud:storage-b-001 (PID = 2020) has been terminated.
   • The Instance sharded_cluster_crud:storage-b-002 (PID = 2021) has been terminated.
   • The Instance sharded_cluster_crud:router-a-001 (PID = 2022) has been terminated.
   • The Instance sharded_cluster_crud:storage-a-001 (PID = 2023) has been terminated.
   • can't "stat" the PID file. Error: "stat /home/testuser/myapp/instances.enabled/sharded_cluster_crud/var/run/storage-a-002/tt.pid: no such file or directory"

Примечание

The error message indicates that storage-a-002 is already not running.

Removing instance artifacts

The tt clean command removes instance artifacts (such as logs or snapshots):

$ tt clean sharded_cluster_crud
   • List of files to delete:

   • /home/testuser/myapp/instances.enabled/sharded_cluster_crud/var/log/storage-a-001/tt.log
   • /home/testuser/myapp/instances.enabled/sharded_cluster_crud/var/lib/storage-a-001/00000000000000001062.snap
   • /home/testuser/myapp/instances.enabled/sharded_cluster_crud/var/lib/storage-a-001/00000000000000001062.xlog
   • ...

Confirm [y/n]:

Enter y and press Enter to confirm removing of artifacts for each instance.

Примечание

The -f option of the tt clean command can be used to remove the files without confirmation.

Preloading Lua scripts and modules

Tarantool supports loading and running chunks of Lua code before starting instances. To load or run Lua code immediately upon Tarantool startup, specify the TT_PRELOAD environment variable. Its value can be either a path to a Lua script or a Lua module name:

To load several scripts or modules, pass them in a single quoted string, separated by semicolons:

$ TT_PRELOAD="preload_script.lua;preload_module" tt start sharded_cluster_crud

If an error happens during the execution of the preload script or module, Tarantool reports the problem and exits.

Commands

Below is a list of tt commands. Run tt COMMAND help to see the detailed help for the given command.

binaries Show a list of installed binaries and their versions
build Build an application locally
cartridge Manage a Cartridge application
cat Print the contents of .snap or .xlog files into stdout
cfg Manage a tt environment configuration
check Check an application file for syntax errors
clean Clean instance files
cluster Manage a cluster’s configuration
completion Generate completion for a specified shell
connect Connect to a Tarantool instance
coredump Manipulate Tarantool core dumps
create Create an application from a template
crud Interact with the CRUD module (Enterprise only)
download Download the Tarantool Enterprise SDK
export Export data to a file (Enterprise only)
help Display help for tt or a specific command
import Import data from a file (Enterprise only)
init Create a new tt environment in the current directory
install Install Tarantool or tt
instances List enabled applications
kill Terminate Tarantool applications or instances
log Print instance logs
logrotate Rotate instance logs
migrations Manage migrations
pack Package an application
play Play the contents of .snap or .xlog files to another Tarantool instance
replicaset Manage replica sets
restart Restart Tarantool applications or instances
rocks Use the LuaRocks package manager
run Run Lua code in a Tarantool instance
search Search available Tarantool and tt versions
start Start Tarantool applications or instances
status Get the current status of applications or instances
stop Stop Tarantool applications or instances
tdg2 Interact with Tarantool Data Grid 2 clusters
uninstall Uninstall Tarantool or tt
version Show the tt version information

Managing binaries in the current environment

$ tt binaries COMMAND [COMMAND_OPTION ...]

tt binaries manages Tarantool and tt binaries installed in the current environment.

COMMAND is one of the following:

list

$ tt binaries list

tt binaries list shows a list of installed binaries and their versions.

To show a list of installed Tarantool versions:

$ tt binaries list
List of installed binaries:
   • tarantool:
        3.1.0 [active]
        2.11.2
   • tt:
        2.3.0
        2.2.1 [active]

switch

$ tt binaries switch [PROGRAM_NAME] [VERSION]

tt binaries switch switches binaries used in the current environment. The possible values of PROGRAM_NAME are:

When called without arguments, the command lets you choose the program and version interactively:

$ tt binaries switch
Use the arrow keys to navigate: ↓ ↑ → ←
? Select program:
  ▸ tarantool
    tarantool-ee
    tt

You can also specify the program name and version in the call.

To view tt versions installed in the current environment and switch between them:

$ tt binaries switch tt
Use the arrow keys to navigate: ↓ ↑ → ←
? Select version:
  ▸ 2.2.1
    2.3.0 [active]

To switch to a specific Tarantool EE version installed in the current environment:

$ tt binaries switch tarantool-ee 3.1.0

Building an application

$ tt build [PATH] [--spec SPEC_FILE_PATH]

tt build builds a Tarantool application locally.

Options

--spec SPEC_FILE_PATH

Path to a .rockspec file to use for the current build

Details

The PATH argument should contain the path to the application directory (that is, to the build source). The default path is . (current directory).

The application directory must contain a .rockspec file to use for the build. If there is more than one .rockspec file in the application directory, specify the one to use in the --spec argument.

tt build builds an application with the tt rocks make command. It downloads the application dependencies into the .rocks directory, making the application ready to run locally.

Pre-build and post-build scripts

In addition to building the application with LuaRocks, tt build can execute pre-build and post-build scripts. These scripts should contain steps to execute right before and after building the application. These files must be named tt.pre-build and tt.post-build correspondingly and located in the application directory.

Примечание

For compatibility with Cartridge applications, the pre-build and post-build scripts can also have names cartridge.pre-build and cartridge.post-build.

tt.pre-build is helpful when your application depends on closed-source rocks, or if the build should contain rocks from a project added as a submodule. You can install these dependencies using the pre-build script before building. Example:

#!/bin/sh

# The main purpose of this script is to build non-standard rocks modules.
# The script will run before `tt rocks make` during application build.

tt rocks make --chdir ./third_party/proj

tt.post-build is a script that runs after tt rocks make. The main purpose of this script is to remove build artifacts from the final package. Example:

#!/bin/sh

# The main purpose of this script is to remove build artifacts from the resulting package.
# The script will run after `tt rocks make` during application build.

rm -rf third_party
rm -rf node_modules
rm -rf doc

Examples

Managing a Cartridge application

Важно

The Tarantool Cartridge framework is deprecated and is not compatible with Tarantool 3.0 and later. This command is added for backward compatibility with earlier versions.

$ tt cartridge COMMAND {[OPTION ...]|SUBCOMMAND}

tt cartridge manages a Cartridge application. COMMAND is one of the following:

admin

$ tt cartridge admin ADMIN_FUNC_NAME [ADMIN_OPTION ...]

tt cartridge admin calls admin functions provided by the application.

Options

--name STRING

(Required) An application name.

-l, --list

List the available admin functions.

--instance STRING

A name of the instance to connect to.

--conn STRING

An address to connect to.

--run-dir STRING

A directory where PID and socket files are stored. Defaults to /var/run/tarantool.

Examples

Get a list of the available admin functions:

$ tt cartridge admin --name APPNAME --list

   • Available admin functions:

probe  Probe instance

Get help for a specific function:

$ tt cartridge admin --name APPNAME probe --help

   • Admin function "probe" usage:

Probe instance

Args:
  --uri string  Instance URI

Call a function with an argument:

$ tt cartridge admin --name APPNAME probe --uri localhost:3301

   • Probe "localhost:3301": OK

bench

$ tt cartridge bench [BENCH_OPTION ...]

tt cartridge bench runs benchmarks for Tarantool.

Options

--url STRING

A Tarantool instance address (the default is 127.0.0.1:3301).

--user STRING

A username used to connect to the instance (the default is guest).

--password STRING

A password used to connect to the instance.

--connections INT

A number of concurrent connections (the default is 10).

--requests INT

A number of simultaneous requests per connection (the default is 10).

--duration INT

The duration of a benchmark test in seconds (the default is 10).

--keysize INT

The size of a key part of benchmark data in bytes (the default is 10).

--datasize INT

The size of a value part of benchmark data in bytes (the default is 20).

--insert INT

A percentage of inserts (the default is 100).

--select INT

A percentage of selects.

--update INT

A percentage of updates.

--fill INT

A number of records to pre-fill the space (the default is 1000000).

failover

$ tt cartridge failover COMMAND [COMMAND_OPTION ...]

tt cartridge failover manages an application failover. The following commands are available:

failover set

$ tt cartridge failover set MODE [FAILOVER_SET_OPTION ...]

Setup failover in the specified mode:

  • stateful
  • eventual
  • disabled

Options:

  • --state-provider STRING: A failover’s state provider. Can be stateboard or etcd2. Used only in the stateful mode.
  • --params STRING: Failover parameters specified in a JSON-formatted string, for example, "{'fencing_timeout': 10', 'fencing_enabled': true}".
  • --provider-params STRING: Failover provider parameters specified in a JSON-formatted string, for example, "{'lock_delay': 14}".

failover setup

$ tt cartridge failover setup --file STRING

Setup failover with parameters described in a file. The failover configuration file defaults to failover.yml.

The failover.yml file might look as follows:

mode: stateful
state_provider: stateboard
stateboard_params:
    uri: localhost:4401
    password: passwd
failover_timeout: 15

failover status

$ tt cartridge failover status

Get the current failover status.

failover disable

$ tt cartridge failover disable

Disable failover.

Options

--name STRING

An application name. Defaults to «package» in rockspec.

--file STRING

A path to the file containing failover settings. Defaults to failover.yml.

repair

$ tt cartridge repair COMMAND [REPAIR_OPTION ...]

tt cartridge repair repairs a running application. The following commands are available:

repair list-topology

$ tt cartridge repair list-topology [REPAIR_OPTION ...]

Get a summary of the current cluster topology.

repair remove-instance

$ tt cartridge repair remove-instance UUID [REPAIR_OPTION ...]

Remove the instance with the specified UUID from the cluster. If the instance isn’t found, raise an error.

repair set-advertise-uri

$ tt cartridge repair set-advertise-uri INSTANCE-UUID NEW-URI [REPAIR_OPTION ...]

Change the instance’s advertise URI. Raise an error if the instance isn’t found or is expelled.

repair set-leader

$ tt cartridge repair set-leader REPLICASET-UUID INSTANCE-UUID [REPAIR_OPTION ...]

Set the instance as the leader of the replica set. Raise an error in the following cases:

  • There is no replica set or instance with that UUID.
  • The instance doesn’t belong to the replica set.
  • The instance has been disabled or expelled.

Options

The following options work with any repair subcommand:

--name

(Required) An application name.

--data-dir

The directory containing the instances“ working directories. Defaults to /var/lib/tarantool.

The following options work with any repair command, except list-topology:

--run-dir

The directory where PID and socket files are stored. Defaults to /var/run/tarantool.

--dry-run

Launch in dry-run mode: show changes but do not apply them.

--reload

Enable instance configuration to reload after the patch.

replicasets

$ tt cartridge replicasets COMMAND [COMMAND_OPTION ...]

tt cartridge replicasets manages an application’s replica sets. The following commands are available:

replicasets setup

$ tt cartridge replicasets setup [--file FILEPATH] [--bootstrap-vshard]

Setup replica sets using a file.

Options:

  • --file: A file with a replica set configuration. Defaults to replicasets.yml.
  • --bootstrap-vshard: Bootstrap vshard upon setup.

replicasets save

$ tt cartridge replicasets save [--file FILEPATH]

Save the current replica set configuration to a file.

Options:

  • --file: A file to save the configuration to. Defaults to replicasets.yml.

replicasets list

$ tt cartridge replicasets list [--replicaset STRING]

List the current cluster topology.

Options:

  • --replicaset STRING: A replica set name.

replicasets join

$ tt cartridge replicasets join INSTANCE_NAME ... [--replicaset STRING]

Join the instance to a cluster. If a replica set with the specified alias isn’t found in the cluster, it is created. Otherwise, instances are joined to an existing replica set.

Options:

  • --replicaset STRING: A replica set name.

replicasets list-roles

$ tt cartridge replicasets list-roles

List the available roles.

replicasets list-vshard-groups

$ tt cartridge replicasets list-vshard-groups

List the available vshard groups.

replicasets add-roles

$ tt cartridge replicasets add-roles ROLE_NAME ... [--replicaset STRING] [--vshard-group STRING]

Add roles to the replica set.

Options:

  • --replicaset STRING: A replica set name.
  • --vshard-group STRING: A vshard group for vshard-storage replica sets.

replicasets remove-roles

$ tt cartridge replicasets remove-roles ROLE_NAME ... [--replicaset STRING]

Remove roles from the replica set.

Options:

  • --replicaset STRING: A replica set name.

replicasets set-weight

$ tt cartridge replicasets set-weight WEIGHT [--replicaset STRING]

Specify replica set weight.

Options:

  • --replicaset STRING: A replica set name.

replicasets set-failover-priority

$ tt cartridge replicasets set-failover-priority INSTANCE_NAME ... [--replicaset STRING]

Configure replica set failover priority.

Options:

  • --replicaset STRING: A replica set name.

replicasets bootstrap-vshard

$ tt cartridge replicasets bootstrap-vshard

Bootstrap vshard.

replicasets expel

$ tt cartridge replicasets expel INSTANCE_NAME ...

Expel one or more instances from the cluster.

Printing the contents of .snap and .xlog files

$ tt cat FILE ... [OPTION ...]

tt cat prints the contents of snapshot (.snap) and WAL (.xlog) files to stdout. A single call of tt cat can print the contents of multiple files.

Options

--format FORMAT

Output format: yaml (default), json, or lua.

--from LSN

Show operations starting from the given LSN.

--to LSN

Show operations up to the given LSN. Default: 18446744073709551615.

--replica ID

Filter the output by replica ID. Can be passed more than once.

When calling tt cat with filters by LSN (--from and --to flags) and replica ID (--replica), remember that LSNs differ across replicas. Thus, if you pass more than one replica ID via --from or --to, the result may not reflect the actual sequence of operations.

--space ID

Filter the output by space ID. Can be passed more than once.

--show-system

Show the contents of system spaces.

Examples

Environment configuration

$ tt cfg COMMAND [OPTION ...]

tt cfg manages a tt environment configuration.

Commands

dump

Print a tt environment configuration.

Options:

  • -r, --raw: Print a raw content of the tt.yaml configuration file.

Examples

Print the current tt environment configuration:

$ tt cfg dump

Checking an application file

$ tt check {FILEPATH | APPLICATION[:APP_INSTANCE]}

tt check checks the syntax correctness of Lua files within Tarantool applications or separate Lua scripts. The files must be stored inside the instances_enabled directory specified in the tt configuration file.

Examples

To check all Lua files in an application directory at once, specify the directory name:

$ tt check app

To check a single Lua file from an application directory, add the path to this file:

$ tt check app/router
# or
$ tt check app/router.lua

Примечание

The .lua extension can be omitted.

Cleaning instance files

$ tt clean APPLICATION[:APP_INSTANCE] [OPTION ...]

tt clean cleans stored files of Tarantool instances: logs, snapshots, and other files. To avoid accidental deletion of files, tt clean shows the files it is going to delete and asks for confirmation.

When called without arguments, cleans files of all applications in the current environment.

Options

-f, --force

Clean files without confirmation.

Examples

Managing cluster configurations

$ tt cluster COMMAND [COMMAND_OPTION ...]

tt cluster manages configurations of Tarantool applications. This command works both with local YAML files in application directories and with centralized configuration storages (etcd or Tarantool-based).

COMMAND is one of the following:

publish

$ tt cluster publish {APPLICATION[:APP_INSTANCE] | CONFIG_URI} [FILE] [OPTION ...]

tt cluster publish publishes a cluster configuration using an arbitrary YAML file as a source.

Publishing local configurations

tt cluster publish can modify local cluster configurations stored in config.yaml files inside application directories.

To write a configuration to a local config.yaml, run tt cluster publish with two arguments:

  • the application name.
  • the path to a YAML file from which the configuration should be taken.
$ tt cluster publish myapp source.yaml

Publishing configurations in centralized storages

tt cluster publish can modify centralized cluster configurations in storages of both supported types: etcd or a Tarantool-based configuration storage.

To publish a configuration from a file to a centralized configuration storage, run tt cluster publish with a URI of this storage’s instance as the target. For example, the command below publishes a configuration from source.yaml to a local etcd instance running on the default port 2379:

$ tt cluster publish "http://localhost:2379/myapp" source.yaml

A URI must include a prefix that is unique for the application. It can also include credentials and other connection parameters. Find the detailed description of the URI format in URI format.

Publishing configurations of specific instances

In addition to whole cluster configurations, tt cluster publish can manage configurations of specific instances within applications: rewrite configurations of existing instances and add new instance configurations.

In this case, it operates with YAML fragments that describe a single instance configuration section. For example, the following YAML file can be a source when publishing an instance configuration:

# instance_source.yaml
iproto:
  listen:
  - uri: 127.0.0.1:3311

To send an instance configuration to a local config.yaml, run tt cluster publish with the application:instance pair as the target argument:

$ tt cluster publish myapp:instance-002 instance_source.yaml

To send an instance configuration to a centralized configuration storage, specify the instance name in the name argument of the storage URI:

$ tt cluster publish "http://localhost:2379/myapp?name=instance-002" instance_source.yaml

If the instance already exists, this call overwrites its configuration with the one from the file.

To add a new instance configuration from a YAML fragment, specify the name to assign to the new instance and its location in the cluster topology – replica set and group – in the --replicaset and --group options.

Примечание

The --group option can be omitted if the configuration contains only one group.

To add a new instance instance-003 to the replicaset-001 replica set:

tt cluster publish "http://localhost:2379/myapp?name=instance-003" instance_source.yaml --replicaset replicaset-001

Configuration validation

tt cluster publish validates configurations against the Tarantool configuration schema and aborts in case of an error. To skip the validation, add the --force option:

$ tt cluster publish myapp source.yaml --force

Publishing configurations with integrity check

Enterprise Edition

The integrity check functionality is supported by the Enterprise Edition only.

When called with the --with-integrity-check option, tt cluster publish generates a checksum of the configurations it publishes. It signs the checksum using the private key passed as the option argument, and writes it into the configuration store.

$ tt cluster publish "http://localhost:2379/myapp" source.yaml --with-integrity-check private.pem

If an application configuration is published this way, it can be checked for integrity using the --integrity-check global option.

$ tt --integrity-check public.pem cluster show myapp
$ tt --integrity-check public.pem start myapp

Learn more about integrity checks upon application startup and in runtime in the tt start reference.

To ensure the configuration integrity when updating it, call tt cluster publish with two options:

  • --integrity-check PUBLIC_KEY global option checks that the configuration wasn’t changed since it was published
  • --with-integrity-check PRIVATE_KEY generates new hash and signature for future integrity checks of the updated configuration.
$ tt --integrity-check public.pem cluster publish \
     --with-integrity-check private.pem \
     "http://localhost:2379/myapp" source.yaml

show

$ tt cluster show {APPLICATION[:APP_INSTANCE] | CONFIG_URI} [OPTION ...]

tt cluster show displays a cluster configuration.

Displaying local configurations

tt cluster show can read local cluster configurations stored in config.yaml files inside application directories.

To print a local configuration from an application’s config.yaml, specify the application name as an argument:

$ tt cluster show myapp

Displaying configurations from centralized storages

tt cluster show can display centralized cluster configurations from configuration storages of both supported types: etcd or a Tarantool-based configuration storage.

To print a cluster configuration from a centralized storage, run tt cluster show with a storage URI including the prefix identifying the application. For example, to print myapp’s configuration from a local etcd storage:

$ tt cluster show "http://localhost:2379/myapp"

Displaying configurations of specific instances

In addition to whole cluster configurations, tt cluster show can display configurations of specific instances within applications. In this case, it prints YAML fragments that describe a single instance configuration section.

To print an instance configuration from a local config.yaml, use the application:instance argument:

$ tt cluster show myapp:instance-002

To print an instance configuration from a centralized configuration storage, specify the instance name in the name argument of the URI:

$ tt cluster show "http://localhost:2379/myapp?name=instance-002"

Configuration validation

To validate configurations when printing them with tt cluster show, enable the validation by adding the --validate option:

$ tt cluster show "http://localhost:2379/myapp" --validate

replicaset

$ tt cluster replicaset SUBCOMMAND {APPLICATION[:APP_INSTANCE] | CONFIG_URI} [OPTION ...]

tt cluster replicaset manages instances in a replica set. It supports the following subcommands:

Важно

tt cluster replicaset works only with centralized cluster configurations. To manage replica set leaders in clusters with local YAML configurations, use tt replicaset promote and tt replicaset demote.

promote

$ tt cluster replicaset promote CONFIG_URI INSTANCE_NAME [OPTION ...]

tt cluster replicaset promote promotes the specified instance, making it a leader of its replica set. This command works on Tarantool clusters with centralized configuration and with failover modes off and manual. It updates the centralized configuration according to the specified arguments and reloads it:

  • off failover mode: the command sets database.mode to rw on the specified instance.

    Важно

    If failover is off, the command doesn’t consider the modes of other replica set members, so there can be any number of read-write instances in one replica set.

  • manual failover mode: the command updates the leader option of the replica set configuration. Other instances of this replica set become read-only.

Example:

$ tt cluster replicaset promote "http://localhost:2379/myapp" storage-001-a

demote

$ tt cluster replicaset demote CONFIG_URI INSTANCE_NAME [OPTION ...]

tt cluster replicaset demote demotes an instance in a replica set. This command works on Tarantool clusters with centralized configuration and with failover mode off.

Примечание

In clusters with manual failover mode, you can demote a read-write instance by promoting a read-only instance from the same replica set with tt cluster replicaset promote.

The command sets the instance’s database.mode to ro and reloads the configuration.

Важно

If failover is off, the command doesn’t consider the modes of other replica set members, so there can be any number of read-write instances in one replica set.

failover

$ tt cluster failover SUBCOMMAND [OPTION ...]

tt cluster failover manages a supervised failover in Tarantool clusters.

Важно

tt cluster failover works only with centralized cluster configurations stored in etcd.

switch

$ tt cluster failover switch CONFIG_URI INSTANCE_NAME [OPTION ...]

tt cluster failover switch appoints the specified instance to be a master. This command accepts the following arguments and options:

  • CONFIG_URI: A URI of the cluster configuration storage.
  • INSTANCE_NAME: An instance name.
  • [OPTION ...]: Options to pass to the command.

In the example below, tt cluster failover switch appoints storage-a-002 to be a master:

$ tt cluster failover switch http://localhost:2379/myapp storage-a-002
To check the switching status, run:
tt cluster failover switch-status http://localhost:2379/myapp b1e938dd-2867-46ab-acc4-3232c2ef7ffe

Note that the command output includes an identifier of the task responsible for switching a master. You can use this identifier to see the status of switching a master instance using tt cluster failover switch-status.

switch-status

$ tt cluster failover switch-status CONFIG_URI TASK_ID

tt cluster failover switch-status shows the status of switching a master instance. This command accepts the following arguments:

  • CONFIG_URI: A URI of the cluster configuration storage.
  • TASK_ID: An identifier of the task used to switch a master instance. You can find the task identifier in the tt cluster failover switch command output.

Example:

$ tt cluster failover switch-status http://localhost:2379/myapp b1e938dd-2867-46ab-acc4-3232c2ef7ffe

Implementation details

The changes that tt cluster replicaset makes to the configuration storage occur transactionally. Each call creates a new revision. In case of a revision mismatch, an error is raised.

If the cluster configuration is distributed over multiple keys in the configuration storage (for example, in two paths /myapp/config/k1 and /myapp/config/k2), the affected instance configuration can be present in more that one of them. If it is found under several different keys, the command prompts the user to choose a key for patching. You can skip the selection by adding the -f/--force option:

$ tt cluster replicaset promote "http://localhost:2379/myapp" storage-001-a --force

In this case, the command selects the key for patching automatically. A key’s priority is determined by the detail level of the instance or replica set configuration stored under this key. For example, when failover is off, a key with instance.database options takes precedence over a key with the only instance field. In case of equal priority, the first key in the lexicographical order is patched.

Authentication

There are three ways to pass the credentials for connecting to the centralized configuration storage. They all apply to both etcd and Tarantool-based storages. The following list shows these ways ordered by precedence, from highest to lowest:

  1. Credentials specified in the storage URI: https://username:password@host:port/prefix:

    $ tt cluster show "http://myuser:p4$$w0rD@localhost:2379/myapp"

  2. tt cluster options -u/--username and -p/--password:

    $ tt cluster show "http://localhost:2379/myapp" -u myuser -p p4$$w0rD

  3. Environment variables TT_CLI_ETCD_USERNAME and TT_CLI_ETCD_PASSWORD:

    $ export TT_CLI_ETCD_USERNAME=myuser
$ export TT_CLI_ETCD_PASSWORD=p4$$w0rD
$ tt cluster show "http://localhost:2379/myapp"

If connection encryption is enabled on the configuration storage, pass the required SSL parameters in the URI arguments.

URI format

A URI of the cluster configuration storage has the following format:

http(s)://[username:password@]host:port[/prefix][?arguments]

Options

-u, --username STRING

A username for connecting to the configuration storage.

See also: Authentication.

-p, --password STRING

A password for connecting to the configuration storage.

See also: Authentication.

--force

Applicable to: publish

Skip validation when publishing. Default: false (validation is enabled).

--group

Applicable to: publish

A name of the configuration group to which the instance belongs.

--replicaset

Applicable to: publish

A name of the replica set to which the instance belongs.

-t, --timeout UINT

Applicable to: failover

A timeout (in seconds) for executing a command. Default: 30.

--validate

Applicable to: show

Validate the printed configuration. Default: false (validation is disabled).

-w, --wait

Applicable to: failover

Wait while the command completes the execution. Default: false (don’t wait).

--with-integrity-check STRING

Enterprise Edition

This option is supported by the Enterprise Edition only.

Applicable to: publish

Generate hashes and signatures for integrity checks.

See also: Publishing configurations with integrity check

Generating completion for tt

$ tt completion SHELL

tt completion generates tab-based completion for tt commands in the specified shell: bash or zsh.

Examples

Generate tt completion for the current bash terminal:

$ . <(tt completion bash)

Примечание

You can add an execution of the completion script to a user’s .bashrc file to make the completion work for this user in all their terminals.

Connecting to a Tarantool instance

$ tt connect {URI|INSTANCE_NAME} [OPTION ...]

tt connect connects to a Tarantool instance by its URI or instance name specified in the current environment.

Options

-u USERNAME, --username USERNAME

A Tarantool user for connecting to the instance.

-p PASSWORD, --password PASSWORD

The user’s password.

-f FILEPATH, --file FILEPATH

Connect and evaluate the script from a file.

- – read the script from stdin.

-i, --interactive

Enter the interactive mode after evaluating the script passed in -f/--file.

-l LANGUAGE, --language LANGUAGE

The input language of the tt interactive console: lua (default) or sql.

-x FORMAT, --outputformat FORMAT

The output format of the tt interactive console: yaml (default), lua, table, ttable.

--sslcertfile FILEPATH

The path to an SSL certificate file for encrypted connections.

--sslkeyfile FILEPATH

The path to a private SSL key file for encrypted connections.

--sslcafile FILEPATH

The path to a trusted certificate authorities (CA) file for encrypted connections.

--sslciphers STRING

The list of SSL cipher suites used for encrypted connections, separated by colons (:).

Details

To connect to an instance, tt typically needs its URI – the host name or IP address and the port.

You can also connect to instances in the same tt environment (that is, those that use the same configuration file and Tarantool installation) by their instance names.

Authentication

When connecting to an instance by its URI, tt connect establishes a remote connection for which authentication is required. Use one of the following ways to pass the username and the password:

  • The -u (--username) and -p (--password) options:

    $ tt connect 192.168.10.10:3301 -u myuser -p p4$$w0rD

  • The connection string:

    $ tt connect myuser:p4$$w0rD@192.168.10.10:3301

  • Environment variables TT_CLI_USERNAME and TT_CLI_PASSWORD:

    $ export TT_CLI_USERNAME=myuser
$ export TT_CLI_PASSWORD=p4$$w0rD
$ tt connect 192.168.10.10:3301

If no credentials are provided for a remote connection, the user is automatically guest.

Примечание

Local connections (by instance name instead of the URI) don’t require authentication.

Encrypted connection

To connect to instances that use SSL encryption, provide the SSL certificate and SSL key files in the --sslcertfile and --sslkeyfile options. If necessary, add other SSL parameters – --sslcafile and --sslciphers.

Script evaluation

By default, tt connect opens an interactive tt console. Alternatively, you can open a connection to evaluate a Lua script from a file or stdin. To do this, pass the file path in the -f (--file) option or use -f - to take the script from stdin.

$ tt connect app -f test.lua

Examples

Manipulating Tarantool core dumps

$ tt coredump COMMAND [COMMAND_OPTION ...]

tt coredump provides commands for manipulating Tarantool core dumps.

To be able to investigate Tarantool crashes, make sure that core dumps are enabled on the host. Here is the instruction on enabling core dumps on Unix systems.

COMMAND is one of the following:

Важно

tt coredump is not supported on macOS.

pack

$ tt coredump pack COREDUMP_FILE

Pack a Tarantool core dump and supporting data into a tar.gz archive. It includes:

Pack a tar.gz file with a Tarantool core dump and supporting data:

$ tt coredump pack name.core

unpack

$ tt coredump unpack ARCHIVE

Unpack a Tarantool core dump archive created with tt coredump pack into a new directory:

$ tt coredump unpack tarantool-core-dump.tar.gz

inspect

$ tt coredump inspect [ARCHIVE|DIRECTORY] [-s]

Inspect a Tarantool core dump with the GNU debugger (gdb). The command argument can be either an archive file produced with tt coredump pack or directory where such an archive is extracted.

Inspect the core dump archive with gdb:

$ tt coredump inspect tarantool-core-dump.tar.gz

Inspect the unpacked core dump directory with gdb:

$ tt coredump inspect tarantool-core-dump

Options

-s

Applicable to: inspect

Specify the location of Tarantool sources.

Creating an application from a template

$ tt create TEMPLATE_NAME [OPTION ...]

tt create creates a new Tarantool application from a template.

Application templates speed up the development of Tarantool applications by defining their initial structure and content. A template can include application code, configuration, build scripts, and other resources.

tt comes with built-in templates for popular use cases. You can also create custom templates for specific purposes.

Built-in templates

There are the following built-in templates:

To create the app1 application in the current tt environment from the built-in vshard_cluster template:

$ tt create vshard_cluster --name app1 -dst /opt/tt/apps/

The command requests cluster topology parameters, such as the number of shards or routers, interactively during the execution.

To create the application in the /opt/tt/apps directory with default cluster topology and force rewrite the application directory if it already exists:

$ tt create vshard_cluster --name app1 -f --non-interactive -dst /opt/tt/apps/

Creating custom application templates

tt searches for custom templates in the directories specified in the templates section of its configuration file.

To create the application app1 from the simple_app custom template in the current directory:

$ tt create simple_app --name app1

Template structure

Application templates are directories with files.

The main file of a template is its manifest. It defines how the applications are instantiated from this template.

A template manifest is a YAML file named MANIFEST.yaml. It can contain the following sections:

  • description – the template description.
  • vars – template variables.
  • pre-hook and post-hook – paths to executables to run before and after the template instantiation.
  • include – a list of files to keep in the application directory after instantiation. If this section is omitted, the application will contain all template files and directories.

All sections are optional.

Example:

description: Template description
vars:
  - prompt: User name
    name: user_name
    default: admin
    re: ^\w+$

  - prompt: Retry count
    default: "3"
    name: retry_count
    re: ^\d+$
pre-hook: ./hooks/pre-gen.sh
post-hook: ./hooks/post-gen.sh
include:
  - init.lua
  - instances.yml

Files and directories of a template are copied to the application directory according to the include section of the manifest (or its absence).

Примечание

Don’t include the .rocks directory in application templates. To specify application dependencies, use the .rockspec files.

There is a special file type *.tt.template. The content of such files is adjusted for each application with the help of template variables. During the instantiation, the variables in these files are replaced with provided values and the *.tt.template extension is removed.

Variables

Templates variables are replaced with their values provided upon the instantiation.

All templates have the name variable. Its value is taken from the --name option.

To add other variables, define them in the vars section of the template manifest. A variable can have the following attributes:

  • prompt: a line of text inviting to enter the variable value in the interactive mode. Required.
  • name: the variable name. Required.
  • default: the default value. Optional.
  • re: a regular expression that the value must match. Optional.

Example:

vars:
  - prompt: Cluster cookie
    name: cluster_cookie
    default: cookie
    re: ^\w+$

Variables can be used in all file names and the content of *.tt template files.

Примечание

Variables don’t work in directory names.

To use a variable, enclose its name with a period in the beginning in double curly braces: {{.var_name}} (as in the Golang text templates syntax).

Examples:

  • init.lua.tt.template file:

    local app_name = {{.name}}
local login = {{.user_name}}

  • A file name {{.user_name}}.txt

Variables receive their values during the template instantiation. By default, tt create asks you to provide the values interactively. You can use the -s (or --non-interactive) option to disable the interactive input. In this case, the values are searched in the following order:

  • In the --var option. Pass a string of the var=value format after the --var option. You can pass multiple variables, each after a separate --var option:

    $ tt create template app --var user_name=admin

  • In a file. Specify var=value pairs in a plain text file, each on a new line, and pass it as the value of the --vars-file option:

    $ tt create template app --vars-file variables.txt

    variables.txt can look like this:

    user_name=admin
password=p4$$w0rd
version=2

If a variable isn’t initialized in any of these ways, the default value from the manifest is used.

You can combine different ways of passing variables in a single call of tt create.

Application directory

By default, the application appears in the directory named after the provided application name (--name value).

To change the application location, use the -dst option.

Options

-d PATH, --dst PATH

Path to the directory where the application will be created.

-f, --force

Force rewrite the application directory if it already exists.

--name NAME

Application name.

-s, --non-interactive

Non-interactive mode.

--var [VAR=VALUE ...]

Variable definition. Usage: --var var_name=value.

--vars-file FILEPATH

Path to the file with variable definitions.

Interacting with the CRUD module

Enterprise Edition

This command is supported by the Enterprise Edition only.

$ tt crud COMMAND [COMMAND_OPTION ...]

tt crud enables the interaction with a cluster using the CRUD module. COMMAND is one of the following:

Downloading Tarantool Enterprise SDK

$ tt download VERSION [OPTION ...]

tt download downloads Tarantool Enterprise SDK from the customer zone.

The VERSION is a part of the SDK archive name between tarantool-enterprise-sdk- and the platform identifier. For example, to download tarantool-enterprise-sdk-gc64-3.0.0-0-gf58f7d82a-r23.linux.x86_64.tar.gz, run:

$ tt download gc64-3.0.0-0-gf58f7d82a-r23

tt automatically chooses the bundle for the current platform.

Authentication

To download the Tarantool Enterprise SDK using tt download, you need to provide access credentials for the Tarantool customer zone. Use one of the following ways to pass the username and the password:

Options

--dev

Download a development build.

--directory-prefix STRING

The downloaded SDK location. Default: . (current directory).

Adding external applications to environments

$ tt enable {APPLICATION|SCRIPT}

tt enable adds an external Tarantool application to the current environment by creating a symlink to it in the instances.enabled directory.

To add the application located in /home/tt-user/external_app to the current tt environment:

$ tt enable /home/tt-user/external_app

Once the application is added, you can work with it the same way as with applications created in this environment.

Exporting data

Enterprise Edition

This command is supported by the Enterprise Edition only.

$ tt [crud|tdg2] export URI SPACE:FILE ... [EXPORT_OPTION ...]

tt [crud|tdg2] export exports a space’s data to a file. Three export commands cover the following cases:

tt [crud|tdg2] export takes the following arguments:

Примечание

Read access to the space is required to export its data.

Output format

tt export exports data in the following formats:

Limitations

Exporting isn’t supported for the interval field type.

Exporting with default settings

The command below exports data of the customers space to the customers.csv file:

$ tt crud export localhost:3301 customers:customers.csv

If the customers space has five fields (id, bucket_id, firstname, lastname, and age), the file with exported data might look like this:

1,477,Andrew,Fuller,38
2,401,Michael,Suyama,46
3,2804,Robert,King,33
# ...

If a tuple contains a null value, for example, [1, 477, 'Andrew', null, 38], it is exported as an empty value:

1,477,Andrew,,38

Exporting headers

To export data with a space’s field names in the first row of the CSV file, use the --header option:

$ tt crud export localhost:3301 customers:customers.csv  \
                 --header

In this case, field values start from the second row, for example:

id,bucket_id,firstname,lastname,age
1,477,Andrew,Fuller,38
2,401,Michael,Suyama,46
3,2804,Robert,King,33
# ...

Exporting compound data

In the CSV format, tt exports empty values by default for fields containing compound data such as arrays or maps. To export compound values in a specific format, use the --compound-value-format option. For example, the command below exports compound values to CSV serialized in JSON:

$ tt crud export localhost:3301 customers:customers.csv  \
                 --compound-value-format json

Exporting from Tarantool Data Grid 2

Примечание

In the TDG2 data model, a type represents a Tarantool space, and an object of a type represents a tuple in the type’s underlying space.

The command below exports data of the customers type from a TDG2 cluster to the customers.jsonl file:

$ tt tdg2 export localhost:3301 customers:customers.jsonl

If the customers type has four fields (id, firstname, lastname, and age), the file with exported data might look like this:

{"age":30,"first_name":"Samantha","id":1,"second_name":"Carter"}
{"age":41,"first_name":"Fay","id":2,"second_name":"Rivers"}
{"age":74,"first_name":"Milo","id":4,"second_name":"Walters"}

If an object contains a null value in a field, this field skipped:

{"age":13,"first_name":"Zachariah","id":3}

Object fields that contain maps with non-string keys are converted to maps with string keys.

TDG2 sets a limit on the number of objects transferred from each storage during a query execution (the hard-limits.returned TDG2 configuration parameter). If an export batch size (--batch-size parameter) is greater than this limit, it is possible that more than hard-limits.returned objects will be requested from one storage and export will fail. To make sure that hard-limits.returned is never exceeded during an export operation, set the export batch size less or equal to this limit.

For example, if your TDG2 cluster has a 1000 objects hard-limits.returned limit:

# tdg2 config.yaml
# ...
hard-limits.returned: 1000

Set the tt tdg2 export batch size less or equal to 1000:

$ tt tdg2 export localhost:3301 customers:customers.jsonl --batch-size=1000

Options

--batch-queue-size INT

The maximum number of tuple batches in a queue between a fetch and write threads (the default is 32).

tt exports data using two threads:

  • A fetch thread makes requests and receives data from a Tarantool instance.
  • A write thread encodes received data and writes it to the output.

The fetch thread uses a queue to pass received tuple batches to the write thread. If a queue is full, the fetch thread waits until the write thread takes a batch from the queue.

--batch-size INT

The number of tuples to transfer per request. The default is:

  • 10000 for tt export and tt crud export.
  • 100 for tt tdg2 export.

Важно

When using tt tdg2 export, make sure that the batch size does not exceed the hard-limits.returned TDG2 parameter value set on the cluster.

--compound-value-format STRING

Applicable to: tt export, tt crud export

A format used to export compound values like arrays or maps. By default, tt exports empty values for fields containing such values.

Supported formats: json.

See also: Exporting compound data.

--header

Applicable to: tt export, tt crud export

Add field names in the first row.

See also: Exporting headers.

--password STRING

A password used to connect to the instance.

--readview

Applicable to: tt export, tt crud export

Export data using a read view.

--username STRING

A username for connecting to the instance.

Displaying help for tt and its commands

$ tt help [COMMAND]

tt help displays help:

Examples

Importing data

Enterprise Edition

This command is supported by the Enterprise Edition only.

$ tt [crud|tdg2] import URI FILE:SPACE [IMPORT_OPTION ...]
# or
$ tt [crud|tdg2] import URI :SPACE < FILE [IMPORT_OPTION ...]

tt [crud|tdg] import imports data from a file to a space. Three import commands cover the following cases:

tt [crud|tdg2] import takes the following arguments:

Примечание

Write access to the space and execute access to universe are required to import data.

Input file format

tt import imports data from the following formats:

Limitations

Importing isn’t supported for the interval field type.

Matching of input and space fields

Automatic matching

Suppose that you have the customers.csv file with a header containing field names in the first row:

id,firstname,lastname,age
1,Andrew,Fuller,38
2,Michael,Suyama,46
3,Robert,King,33
# ...

If the target customers space has fields with the same names, you can import data using the --header and --match options specified as follows:

$ tt crud import localhost:3301 customers.csv:customers \
                 --header \
                 --match=header

In this case, fields in the input file and the target space are matched automatically. You can also match fields manually if field names in the input file and the target space differ. Note that if you’re importing data into a cluster, you don’t need to specify the bucket_id field. The CRUD module generates bucket_id values automatically.

Manual matching

The --match option enables importing data by matching field names in the input file and the target space manually. Suppose that you have the following customers.csv file with four fields:

customer_id,name,surname,customer_age
1,Andrew,Fuller,38
2,Michael,Suyama,46
3,Robert,King,33
# ...

If the target customers space has the id, firstname, lastname, and age fields, you can configure mapping as follows:

$ tt crud import localhost:3301 customers.csv:customers \
                 --header \
                 --match "id=customer_id;firstname=name;lastname=surname;age=customer_age"

Similarly, you can configure mapping using numeric field positions in the input file:

$ tt crud import localhost:3301 customers.csv:customers \
                 --header \
                 --match "id=1;firstname=2;lastname=3;age=4"

Below are the rules if some fields are missing in input data or space:

  • If a space has fields that are not specified in input data, tt [crud] import tries to insert null values.
  • If input data contains fields missing in a target space, these fields are ignored.

Importing bucket_id into sharded clusters

When importing data into a CRUD-enabled sharded cluster, tt crud import ignores the bucket_id field values from the input file. This allows CRUD to automatically manage data distribution in the cluster by generating new bucket_id for tuples during import.

If you need to preserve the original bucket_id values, use the --keep-bucket-id option:

$ tt crud import localhost:3301 customers.csv:customers \
                 --keep-bucket-id \
                 --header \
                 --match=header

Handling duplicate primary key errors

The --on-exist option enables you to control data import when a duplicate primary key error occurs. In the example below, values already existing in the space are replaced with new ones:

$ tt crud import localhost:3301 customers.csv:customers \
                 --on-exist replace

Handling parsing errors

To skip rows whose data cannot be parsed correctly, use the --on-error option as follows:

$ tt crud import localhost:3301 customers.csv:customers \
                 --on-error skip

Importing into Tarantool Data Grid 2

Примечание

In the TDG2 data model, a type represents a Tarantool space, and an object of a type represents a tuple in the type’s underlying space.

The command below imports objects of the customers type into a TDG2 cluster. The objects are described in the customers.jsonl file.

$ tt tdg2 import localhost:3301 customers.jsonl:customers

The input file can look like this:

{"age":30,"first_name":"Samantha","id":1,"second_name":"Carter"}
{"age":41,"first_name":"Fay","id":2,"second_name":"Rivers"}
{"age":74,"first_name":"Milo","id":4,"second_name":"Walters"}

Примечание

Since JSON describes objects in maps with string keys, there is no way to import a field value that is a map with a non-string key.

In case of an error during TDG2 import, tt tdg2 import rolls back the changes made within the current batch on the storage where the error has happened (per-storage rollback) and reports an error. On other storages, objects from the same batch can be successfully imported. So, the rollback process of tt tdg2 import is the same as the one of tt crud import with the --rollback-on-error option.

Since object batches can be imported partially (per-storage rollback), the absence of error matching complicates the debugging in case of errors. To minimize this effect, the default batch size (--batch-size) for tt tdg2 import is 1. This makes the debugging straightforward: you always know which object caused the error. On the other hand, this decreases the performance in comparison to import in larger batches.

If you increase the batch size, tt informs you about the possible issues and asks for an explicit confirmation to proceed. To automatically confirm a batch import operation, add the --force option:

$ tt tdg2 import localhost:3301 customers.jsonl:customers \
                 --batch-size=100 \
                 --force

Options

--batch-size INT

Applicable to: tt crud import, tt tdg2 import

The number of tuples to transfer per request. The default is:

--dec-sep STRING

Applicable to: tt import, tt crud import

The string of symbols that defines decimal separators for numeric data (the default is .,).

Примечание

Symbols specified in this option cannot intersect with --th-sep.

--delimiter STRING

Applicable to: tt import, tt crud import

A symbol that defines a field value delimiter. For CSV, the default delimiter is a comma (,). To use a tab character as a delimiter, set this value as tab:

$ tt crud import localhost:3301 customers.csv:customers \
                 --delimiter tab

Примечание

A delimiter cannot be \r, \n, or the Unicode replacement character (U+FFFD).

--error STRING

The name of a file containing rows that are not imported (the default is error).

See also: Handling parsing errors.

--force

Applicable to: tt tdg2 import

Automatically confirm importing into TDG2 with --batch-size greater than one.

--format STRING

A format of input data.

Supported formats: csv.

--header

Applicable to: tt import, tt crud import

Process the first line as a header containing field names. In this case, field values start from the second line.

See also: Matching of input and space fields.

--keep-bucket-id

Applicable to: tt crud import

Preserve original values of the bucket_id field.

See also: Importing bucket_id into sharded clusters.

--log STRING

The name of a log file containing information about import errors (the default is import). If the log file already exists, new data is written to this file.

--match STRING

Applicable to: tt import, tt crud import

Configure matching between field names in the input file and the target space.

See also: Matching of input and space fields.

--null STRING

Applicable to: tt import, tt crud import

A value to be interpreted as null when importing data. By default, an empty value is interpreted as null. For example, a tuple imported from the following row …

1,477,Andrew,,38

… should look as follows: [1, 477, 'Andrew', null, 38].

--on-error STRING

An action performed if a row to be imported cannot be parsed correctly. Possible values:

  • stop: stop importing data.
  • skip: skip rows whose data cannot be parsed correctly.

Duplicate primary key errors are handled using the --on-exist option.

See also: Handling parsing errors.

--on-exist STRING

An action performed if a duplicate primary key error occurs. Possible values:

  • stop: stop importing data.
  • skip: skip existing values when importing.
  • replace: replace existing values when importing.

Other errors are handled using the --on-error option.

See also: Handling duplicate primary key errors.

--password STRING

A password used to connect to the instance.

--progress STRING

The name of a progress file that stores the following information:

  • The positions of lines that were not imported at the last launch.
  • The last position that was processed at the last launch.

If a file with the specified name exists, it is taken into account when importing data. tt import tries to insert lines that were not imported and then continues importing from the last position.

At each launch, the content of a progress file with the specified name is overwritten. If the file with the specified name does not exist, a progress file is created with the results of this run.

Примечание

If the option is not set, then this mechanism is not used.

--quote STRING

Applicable to: tt import, tt crud import

A symbol that defines a quote. For CSV, double quotes are used by default ("). The double symbol of this option acts as the escaping symbol within input data.

-success STRING

The name of a file with rows that were imported (the default is success). Overwrites the file if it already exists.

--th-sep STRING

Applicable to: tt import, tt crud import

The string of symbols that define thousand separators for numeric data. The default value includes a space and a backtick `. This means that 1 000 000 and 1`000`000 are both imported as 1000000.

Примечание

Symbols specified in this option cannot intersect with --dec-sep.

--username STRING

A username for connecting to the instance.

--rollback-on-error

Applicable to: tt crud import

Specify whether any operation failed on a storage leads to rollback of a batch import on this storage.

Примечание

tt tdg2 import always works as if --rollback-on-error is true.

Creating a tt environment

$ tt init

tt init creates a tt environment in the current directory. This includes:

Details

Важно

The Tarantool Cartridge framework is deprecated and is not compatible with Tarantool 3.0 and later. This command is added for backward compatibility with earlier versions.

tt init checks the existence of configuration files for Cartridge (cartridge.yml) or the tarantoolctl utility (.tarantoolctl) in the current directory. If such files are found, tt generates an environment that uses the same directories:

If there is no cartridge.yml or .tarantoolctl files in the current directory, tt init creates a default environment in it. This includes creating the following directories and files:

Example

Create a tt environment in the current directory:

$ tt init

Installing Tarantool software

$ tt install PROGRAM_NAME [VERSION|COMMIT_HASH|PR_ID] [OPTION ...]

tt install installs the latest or an explicitly specified version of Tarantool or tt. The possible values of PROGRAM_NAME are:

Примечание

For tarantool-ee, account credentials are required. Specify them in a file (see the ee section of the configuration file) or provide them interactively.

Additionally, tt install can build open source programs tarantool and tt from a specific commit or a pull request on their GitHub repositories.

To uninstall a Tarantool or tt version, use tt uninstall.

Options

--dynamic

Applicable to: tarantool, tarantool-ee

Use dynamic linking for building Tarantool.

-f, --force

Skip dependency check before installation.

--local-repo

Install a program from the local repository, which is specified in the repo section of the tt configuration file.

--no-clean

Don’t delete temporary files.

--reinstall

Reinstall a previously installed program.

--use-docker

Applicable to: tarantool, tarantool-ee

Build Tarantool in an Ubuntu 18.04 Docker container.

Details

When called without an explicitly specified version, tt install installs the latest available version. To check versions available for installation, use tt search.

By default, available versions of Tarantool Community Edition and tt are taken from their git repositories. Their installation includes building from sources, which requires some tools and dependencies, such as a C compiler. Make sure they are available in the system.

Tarantool Enterprise Edition is installed from prebuilt packages.

Authentication

To install Tarantool EE using tt install, you need to provide access credentials for the Tarantool customer zone. Use one of the following ways to pass the username and the password:

  • A text file specified in the ee.credential_path parameter of the tt enviromnment configuration:

    # tt.yaml
# ...
ee:
  credential_path: cred.txt

    cred.txt should contain a username and a password on separate lines:

    myuser@tarantool.io
p4$$w0rD

  • Environment variables TT_CLI_EE_USERNAME and TT_CLI_EE_PASSWORD:

    $ export TT_CLI_EE_USERNAME=myuser@tarantool.io
$ export TT_CLI_EE_PASSWORD=p4$$w0rD
$ tt install tarantool-ee

Development versions

tt install can be used to build custom Tarantool and tt versions for development purposes from commits and pull requests on their GitHub repositories.

To build Tarantool or tt from a specific commit on their GitHub repository, pass the commit hash (7 or more characters) after the program name. If you want to use a PR as a source, provide a pr/<PR_ID> argument:

$ tt install tarantool 03c184d
$ tt install tt pr/50

If you build Tarantool from sources, you can install local builds to the current tt environment by running tt install with the tarantool-dev program name and the path to the build:

$ tt install tarantool-dev ~/src/tarantool/build

Local repositories

You can also set up a local repository with installation files you need. To use it, specify its location in the repo section of the tt configuration file and run tt install with the --local-repo flag.

Example

Listing enabled applications

$ tt instances

tt instances shows the list of enabled applications and their instances in the current environment.

Примечание

Enabled applications are applications that are stored inside the instances_enabled directory specified in the tt configuration file. They can be either running or not. To check if an application is running, use tt status.

Example

Terminating Tarantool instances

$ tt kill APPLICATION[:APP_INSTANCE]

tt kill terminates instances with SIGQUIT and SIGKILL signals.

To terminate all instances of the app application:

$ tt kill app

To terminate the storage-001-r instance of the app application without confirmation:

$ tt kill app:storage-001-r --force

To terminate the storage-001-r instance of the app application and generate its core dump:

$ tt kill app:storage-001-r --dump

Options

-d, --dump

Generate core dumps of terminated processes.

-f, --force

Kill instances without confirmation.

Printing Tarantool logs

$ tt log [APPLICATION[:APP_INSTANCE]]

tt log prints the last lines of instance logs.

To print 10 last log lines of all the app application instances:

$ tt log app

To print 50 last log lines of the router instance of the app application:

$ tt log -n 50 app:router

To keep printing logs of the app application instances as they grow:

$ tt log -f app

Options

-f, --follow

Keep printing new lines added to the log file.

-n, --lines

The number of last lines to output. Default: 10.

Rotating instance logs

$ tt logrotate APPLICATION[:APP_INSTANCE]

tt logrotate rotates logs of a Tarantool application or specific instances, and the tt log. For example, you need to call this function to continue logging after a log rotation program renames or moves instances“ logs. Learn more about rotating logs.

Calling tt logrotate on an application has the same effect as executing the built-in log.rotate() function on all its instances.

Examples

Rotate logs of the app application’s instances:

$ tt logrotate app

Managing centralized migrations

Enterprise Edition

This command is supported by the Enterprise Edition only.

$ tt migrations COMMAND [COMMAND_OPTION ...]

tt migrations manages centralized migrations in a Tarantool EE cluster. See Centralized migrations with tt for a detailed guide on using the centralized migrations mechanism.

Важно

Only Tarantool EE clusters with etcd centralized configuration storage are supported.

COMMAND is one of the following:

publish

$ tt migrations publish ETCD_URI [MIGRATIONS_DIR | MIGRATION_FILE] [OPTION ...]

tt migrations publish sends the migration files to the cluster’s centralized configuration storage for future execution.

By default, the command sends all files stored in migrations/ inside the current directory.

$ tt migrations publish "https://user:pass@localhost:2379/myapp"

To select another directory with migration files, provide a path to it as the command argument:

$ tt migrations publish "https://user:pass@localhost:2379/myapp" my_migrations

To publish a single migration from a file, use its name or path as the command argument:

$ tt migrations publish "https://user:pass@localhost:2379/myapp" migrations/000001_create_space.lua

Optionally, you can provide a key to use as a migration identifier instead of the filename:

$ tt migrations publish "https://user:pass@localhost:2379/myapp" file.lua  \
                        --key=000001_create_space.lua

When publishing migrations, tt performs checks for:

Предупреждение

Using the options that ignore checks when publishing migration may cause migration inconsistency in the cluster.

apply

$ tt migrations apply ETCD_URI [OPTION ...]

tt migrations apply applies published migrations to the cluster. It executes all migrations from the cluster’s centralized configuration storage on all its read-write instances (replica set leaders).

$ tt migrations apply "https://user:pass@localhost:2379/myapp"  \
                    --tarantool-username=admin --tarantool-password=pass

To apply a single published migration, pass its name in the --migration option:

$ tt migrations apply "https://user:pass@localhost:2379/myapp"  \
                    --tarantool-username=admin --tarantool-password=pass  \
                    --migration=000001_create_space.lua

To apply migrations on a single replica set, specify the replicaset option:

$ tt migrations apply "https://user:pass@localhost:2379/myapp"  \
                    --tarantool-username=admin --tarantool-password=pass  \
                    --replicaset=storage-001

The command also provides options for migration troubleshooting: --ignore-order-violation, --force-reapply, and --ignore-preceding-status. Learn to use them in Troubleshooting migrations.

Предупреждение

The use of migration troubleshooting options may lead to migration inconsistency in the cluster. Use them only for local development and testing purposes.

status

$ tt migrations status ETCD_URI [OPTION ...]

tt migrations status prints the list of migrations published to the centralized storage and the result of their execution on the cluster instances.

Possible migration statuses are:

To get the list of migrations stored in the given etcd storage and information about their execution on the cluster, run:

$ tt migrations status "https://user:pass@localhost:2379/myapp"  \
                       --tarantool-username=admin --tarantool-password=pass

If the cluster uses SSL encryption, add SSL options. Learn more in Authentication.

Use the --migration and --replicaset options to get information about specific migrations or replica sets:

$ tt migrations status "https://user:pass@localhost:2379/myapp"  \
                     --tarantool-username=admin --tarantool-password=pass \
                     --replicaset=storage-001 --migration=000001_create_writers_space.lua

The --display-mode option allows to tailor the command output:

To find out the results of a migration execution on a specific replica set in the cluster, run:

$ tt migrations status "https://user:pass@localhost:2379/myapp"  \
                       --tarantool-username=admin --tarantool-password=pass  \
                       --replicaset=storage-001 --display-mode=cluster

stop

$ tt migrations stop ETCD_URI [OPTION ...]

tt migrations stop stops the execution of migrations in the cluster.

Предупреждение

Calling tt migration stop may cause migration inconsistency in the cluster.

To stop the execution of a migration currently running in the cluster:

$ tt migrations stop "https://user:pass@localhost:2379/myapp"  \
                     --tarantool-username=admin --tarantool-password=pass

tt migrations stop interrupts a single migration. If you call it to interrupt the process that applies multiple migrations, the ones completed before the call receive the APPLIED status. The migration is interrupted by the call remains in APPLY_STARTED.

remove

$ tt migrations remove ETCD_URI [OPTION ...]

tt migrations remove removes published migrations from the centralized storage. With additional options, it can also remove the information about the migration execution on the cluster instances.

To remove all migrations from a specified centralized storage:

$ tt migrations remove "https://user:pass@localhost:2379/myapp"  \
                       --tarantool-username=admin --tarantool-password=pass

To remove a specific migration, pass its name in the --migration option:

$ tt migrations remove "https://user:pass@localhost:2379/myapp"  \
                       --tarantool-username=admin --tarantool-password=pass  \
                       --migration=000001_create_writers_space.lua

Before removing migrations, the command checks their status on the cluster. To ignore the status and remove migrations anyway, add the --force-remove-on=config-storage option:

$ tt migrations remove "https://user:pass@localhost:2379/myapp"  \
                        --force-remove-on=config-storage

Примечание

In this case, cluster credentials are not required.

To remove migration execution information from the cluster (clear the migration status), use the --force-remove-on=cluster option:

$ tt migrations remove "https://user:pass@localhost:2379/myapp"  \
                       --tarantool-username=admin --tarantool-password=pass  \
                       --force-remove-on=cluster

To clear all migration information from the centralized storage and cluster, use the --force-remove-on=all option:

$ tt migrations remove "https://user:pass@localhost:2379/myapp"  \
                       --tarantool-username=admin --tarantool-password=pass  \
                       --force-remove-on=all

Authentication

Since tt migrations operates migrations via a centralizes etcd storage, it needs credentials to access this storage. There are two ways to pass etcd credentials:

Credentials specified in the URI have a higher priority.

For commands that connect to the cluster (that is, all except publish), Tarantool credentials are also required. The are passed in the --tarantool-username and --tarantool-password options.

If the cluster uses SSL traffic encryption, provide the necessary connection parameters in the --tarantool-ssl* options: --tarantool-sslcertfile, --tarantool-sslkeyfile, and other. All options are listed in Options.

Options

--acquire-lock-timeout INT

Applicable to: apply

Migrations fiber lock acquire timeout in seconds. Default: 60. Fiber lock is used to prevent concurrent migrations run

--config-storage-password STRING

A password for connecting to the centralized migrations storage (etcd).

See also: Authentication.

--config-storage-username STRING

A username for connecting to the centralized migrations storage (etcd).

See also: Authentication.

--display-mode STRING

Applicable to: status

Display only specific information. Possible values:

  • config-storage – information about migrations published to the centralized storage.
  • cluster – information about migration applied on the cluster.

See also: status.

--execution-timeout INT

Applicable to: apply, remove, status, stop

A timeout for completing the operation on a single Tarantool instance, in seconds. Default values:

  • 3 for remove, status, and stop
  • 3600 for apply
--force-reapply

Applicable to: apply

Apply migrations disregarding their previous status.

Предупреждение

Using this option may lead to migrations inconsistency in the cluster.

--force-remove-on STRING

Applicable to: remove

Remove migrations disregarding their status. Possible values:

  • config-storage: remove migrations on etcd centralized migrations storage disregarding the cluster apply status.
  • cluster: remove migrations status info only on a Tarantool cluster.
  • all to execute both config-storage and cluster force removals.

Предупреждение

Using this option may lead to migrations inconsistency in the cluster.

--ignore-order-violation

Applicable to: apply, publish

Skip migration scenarios order check before publish.

Предупреждение

Using this option may lead to migrations inconsistency in the cluster.

--ignore-preceding-status

Applicable to: apply

Skip preceding migrations status check on apply.

Предупреждение

Using this option may lead to migrations inconsistency in the cluster.

--key STRING

Applicable to: publish

Put scenario to /<prefix>/migrations/scenario/<key> etcd key instead. Only for single file publish.

--migration STRING

Applicable to: apply, remove, status

A migration to apply, remove, or check status.

--overwrite

Applicable to: publish

overwrite existing migration storage keys.

Предупреждение

Using this option may lead to migrations inconsistency in the cluster.

--replicaset STRING

Applicable to: apply, remove, status, stop

Execute the operation only on the specified replica set.

--skip-syntax-check

Applicable to: publish

Skip syntax check before publish.

Предупреждение

Using this option may cause further tt migrations calls to fail.

--tarantool-auth STRING

Applicable to: apply, remove, status, stop

Authentication type used to connect to the cluster instances.

--tarantool-connect-timeout INT

Applicable to: apply, remove, status, stop

Tarantool cluster instances connection timeout, in seconds. Default: 3.

--tarantool-password STRING

Applicable to: apply, remove, status, stop

A password used to connect to the cluster instances.

--tarantool-sslcafile STRING

Applicable to: apply, remove, status, stop

SSL CA file used to connect to the cluster instances.

--tarantool-sslcertfile STRING

Applicable to: apply, remove, status, stop

SSL cert file used to connect to the cluster instances.

--tarantool-sslciphers STRING

Applicable to: apply, remove, status, stop

Colon-separated list of SSL ciphers used to connect to the cluster instances.

--tarantool-sslkeyfile STRING

Applicable to: apply, remove, status, stop

SSL key file used to connect to the cluster instances.

--tarantool-sslpassword STRING

Applicable to: apply, remove, status, stop

SSL key file password used to connect to the cluster instances.

--tarantool-sslpasswordfile STRING

Applicable to: apply, remove, status, stop

File with list of password to SSL key file used to connect to the cluster instances.

--tarantool-use-ssl

Applicable to: apply, remove, status, stop

Whether SSL is used to connect to the cluster instances.

--tarantool-username STRING

Applicable to: apply, remove, status, stop

A username for connecting to the Tarantool cluster instances.

Packaging the application

$ tt pack TYPE [OPTION ...] ..

tt pack packages an application into a distributable bundle of the specified TYPE:

Example: a DEB package

The command below creates a DEB package with all applications from the current tt environment:

$ tt pack deb

This command generates a .deb file whose name depends on the environment directory name and the operating system architecture, for example, test-env_0.1.0.0-1_x86_64.deb. The package contains the following files:

You can also pass various options to the tt pack command to adjust generation properties, for example, customize a bundle name, choose which artifacts should be included, specify the required application dependencies.

systemd unit parameters

You can customize your application’s systemd unit file generated by tt pack. To add parameters to the unit file, define them in a YAML file named systemd-unit-params.yml in the application directory.

$ tt pack rpm # unit file with parameters from systemd-unit-params.yml if it exists

You can also pass unit parameters from an arbitrary file by adding the --unit-params-file option to the tt pack call:

$ tt pack rpm --unit-params-file my-params.yml # unit file with parameters from my-params.yml

Важно

The systemd-unit-params.yml file has a higher priority than the --unit-params-file option. If this file exists, it overrides parameters from the file passed in the option.

tt pack supports the following systemd unit parameters:

An example of the systemd-unit-params.yml file:

FdLimit: 200
instance-env:
  INSTANCE: "inst:%i"
  TARANTOOL_WORKDIR: "/tmp"

Generating files for integrity checks

Enterprise Edition

The integrity check functionality is supported by the Enterprise Edition only.

tt pack can generate checksums and signatures to use for integrity checks when running the application. These files are:

To generate checksums and signatures for integrity check, use the --with-integrity-check option. Its argument must be an RSA private key.

Примечание

You can generate a key pair using OpenSSL 3 as follows:

$ openssl genrsa -traditional -out private.pem 2048
$ openssl rsa -in private.pem -pubout > public.pem

To create a tar.gz archive with integrity check artifacts:

$ tt pack tgz --with-integrity-check private.pem

Learn how to perform integrity checks at the application startup and in runtime in the tt start reference.

Options

--all

Include all artifacts in a bundle. In this case, a bundle might include snapshots, WAL files, and logs.

--app-list APPLICATIONS

Specify the applications included in a bundle.

Example

$ tt pack tgz --app-list app1,app3
--cartridge-compat

Applicable to: tgz

Package a Cartridge CLI-compatible archive.

Важно

The Tarantool Cartridge framework is deprecated and is not compatible with Tarantool 3.0 and later. This command is added for backward compatibility with earlier versions.

--deps STRINGS

Applicable to: deb, rpm

Specify dependencies included in RPM and DEB packages.

Example

$ tt pack deb --deps 'wget,make>0.1.0,unzip>1,unzip<=7'
--deps-file STRING

Applicable to: deb, rpm

Specify the path to a file containing dependencies included in RPM and DEB packages. For example, the package-deps.txt file below contains several dependencies and their versions:

unzip==6.0
neofetch>=6,<7
gcc>8

If this file is placed in the current directory, a tt pack command might look like this:

$ tt pack deb --deps-file package-deps.txt
--filename

Specify a bundle name.

Example

$ tt pack tgz --filename sample-app.tar.gz
--name PACKAGE_NAME

Specify a package name.

Example

$ tt pack tgz --name sample-app --version 1.0.1
--preinst

Applicable to: deb, rpm

Specify the path to a pre-install script for RPM and DEB packages.

Example

$ tt pack deb --preinst pre.sh
--postinst

Applicable to: deb, rpm

Specify the path to a post-install script for RPM and DEB packages.

Example

$ tt pack deb --postinst post.sh
--tarantool-version

Specify a Tarantool version for packaging in a Docker container. For use with --use-docker only.

--unit-params-file

The path to a file with custom systemd unit parameters.

--use-docker

Build a package in an Ubuntu 18.04 Docker container. To specify a Tarantool version to use in the container, add the --tarantool-version option.

Before executing tt pack with this option, make sure Docker is running.

--version PACKAGE_VERSION

Specify a package version.

Example

$ tt pack tgz --name sample-app --version 1.0.1
--with-binaries

Include Tarantool and tt binaries in a bundle.

--with-integrity-check PRIVATE_KEY

Generate checksums and signatures for integrity checks at the application startup.

See also: Generating files for integrity checks

--with-tarantool-deps

Add Tarantool and tt as package dependencies.

--without-binaries

Don’t include Tarantool and tt binaries in a bundle.

--without-modules

Don’t include external modules in a bundle.

Playing the contents of .snap and .xlog files to a Tarantool instance

$ tt play URI FILE ... [OPTION ...]

tt play plays the contents of snapshot (.snap) and WAL (.xlog) files to another Tarantool instance. A single call of tt play can play multiple files.

Options

-u USERNAME, --username USERNAME

A Tarantool user for connecting to the instance.

-p PASSWORD, --password PASSWORD

The user’s password.

--from LSN

Play operations starting from the given LSN.

--to LSN

Play operations up to the given LSN. Default: 18446744073709551615.

--replica ID

Filter the operations by replica ID. Can be passed more than once.

When calling tt cat with filters by LSN (--from and --to flags) and replica ID (--replica), remember that LSNs differ across replicas. Thus, if you pass more than one replica ID via --from or --to, the result may not reflect the actual sequence of operations.

--space ID

Filter the output by space ID. Can be passed more than once.

--show-system

Show the operations on system spaces.

Details

tt play plays operations from .xlog and .snap files to the destination instance one by one. All data changes happen the same way as if they were performed on this instance. This means that:

Authentication

Use one of the following ways to pass the username and the password when connecting to the instance:

  • The -u (--username) and -p (--password) options:

    $ tt play 192.168.10.10:3301 00000000000000000000.xlog -u myuser -p p4$$w0rD

  • The connection string:

    $ tt play myuser:p4$$w0rD@192.168.10.10:3301 00000000000000000000.xlog

  • Environment variables TT_CLI_USERNAME and TT_CLI_PASSWORD:

    $ export TT_CLI_USERNAME=myuser
$ export TT_CLI_PASSWORD=p4$$w0rD
$ tt play 192.168.10.10:3301 00000000000000000000.xlog

Examples

Managing replica sets

$ tt replicaset COMMAND {APPLICATION[:APP_INSTANCE] | URI} [OPTIONS ...]
# or
$ tt rs COMMAND {APPLICATION[:APP_INSTANCE] | URI} [OPTIONS ...]

tt replicaset (or tt rs) manages a Tarantool replica set.

COMMAND is one of the following:

status

$ tt replicaset status {APPLICATION[:APP_INSTANCE] | URI} [OPTIONS ...]
# or
$ tt rs status {APPLICATION[:APP_INSTANCE] | URI} [OPTIONS ...]

tt replicaset status (tt rs status) shows the current status of a replica set.

Displaying status of all replica sets

To view the status of all replica sets of an application in the current tt environment, run tt replicaset status with the application name:

$ tt replicaset status myapp

Displaying status of a single replica set

To view the status of a single replica set of an application, run tt replicaset status with a name or a URI of an instance from this replica set:

$ tt replicaset status myapp:storage-001-a

For a replica outside the current tt environment, specify its URI and access credentials:

$ tt replicaset status 192.168.10.10:3301 -u myuser -p p4$$w0rD

Learn about other ways to provide user credentials in Authentication.

promote

$ tt replicaset promote {APPLICATION:APP_INSTANCE | URI} [OPTIONS ...]
# or
$ tt rs promote {APPLICATION:APP_INSTANCE | URI} [OPTIONS ...]

tt replicaset promote (tt rs promote) promotes the specified instance, making it a leader of its replica set. This command works on Tarantool clusters with a local YAML configuration and Cartridge clusters.

Примечание

To promote an instance in a Tarantool cluster with a centralized configuration, use tt cluster replicaset promote.

Promoting in clusters with local YAML configurations

tt replicaset promote works on Tarantool clusters with local YAML configurations with failover modes off, manual, and election.

In failover modes off or manual, this command updates the cluster configuration file according to the specified arguments and reloads it:

  • off failover mode: the command sets database.mode to rw on the specified instance.

    Важно

    If failover is off, the command doesn’t consider the modes of other replica set members, so there can be any number of read-write instances in one replica set.

  • manual failover mode: the command updates the leader option of the replica set configuration. Other instances of this replica set become read-only.

Example:

$ tt replicaset promote my-app:storage-001-a

If some members of the affected replica set are running outside the current tt environment, tt replicaset promote can’t ensure the configuration reload on them and reports an error. You can skip this check by adding the -f/--force option:

$ tt replicaset promote my-app:storage-001-a --force

In the election failover mode, tt replicaset promote initiates the new leader election by calling box.ctl.promote() on the specified instance. The --timeout option can be used to specify the election completion timeout:

$ tt replicaset promote my-app:storage-001-a --timeout=10

Promoting in Cartridge clusters

Важно

The Tarantool Cartridge framework is deprecated and is not compatible with Tarantool 3.0 and later. This command is added for backward compatibility with earlier versions.

tt replicaset promote promotes instances in Cartridge clusters as follows:

  • disabled or eventual failover mode: the command changes the instance failover priority.

    Важно

    In these cases, consistency is not guaranteed and replication conflicts may occur.

  • eventual or raft failover mode: the command calls cartridge.failover_promote() and waits until the instance transitions to the read-write mode. If the -f/--force option is specified, the force_inconsistency option of cartridge.failover_promote is set to true.

$ tt replicaset promote my-cartridge-app:storage-001-a --force

Learn more about Cartridge failover modes.

demote

$ tt replicaset demote APPLICATION:APP_INSTANCE [OPTIONS ...]
# or
$ tt rs demote APPLICATION:APP_INSTANCE [OPTIONS ...]

tt replicaset demote (tt rs demote) demotes an instance in a Tarantool cluster with a local YAML configuration.

Примечание

To demote an instance in a Tarantool cluster with a centralized configuration, use tt cluster replicaset demote.

Demoting in clusters with local YAML configurations

tt replicaset demote can demote instances in Tarantool clusters with local YAML configurations with failover modes off and election.

Примечание

In clusters with manual failover mode, you can demote a read-write instance by promoting a read-only instance from the same replica set with tt replicaset promote.

In the off failover mode, tt replicaset demote sets the instance’s database.mode to ro and reloads the configuration.

Важно

If failover is off, the command doesn’t consider the modes of other replica set members, so there can be any number of read-write instances in one replica set.

If some members of the affected replica set are running outside the current tt environment, tt replicaset demote can’t ensure the configuration reload on them and reports an error. You can skip this check by adding the -f/--force option:

$ tt replicaset demote my-app:storage-001-a --force

In the election failover mode, tt replicaset demote initiates a leader election in the replica set. The specified instance’s replication.election_mode is changed to voter for this election, which guarantees that another instance is elected as a new replica set leader.

The --timeout option can be used to specify the election completion timeout:

$ tt replicaset demote my-app:storage-001-a --timeout=10

expel

$ tt replicaset expel APPLICATION:APP_INSTANCE [OPTIONS ...]
# or
$ tt rs expel  APPLICATION[:APP_INSTANCE] [OPTIONS ...]

tt replicaset expel (tt rs expel) expels an instance from the cluster.

$ tt replicaset expel myapp:storage-001-b

The command supports the --config, --cartridge, and --custom options that force the use of a specific orchestrator.

To expel an instance from a Cartridge cluster:

$ tt replicaset expel my-cartridge-app:storage-001-b --cartridge

vshard

$ tt replicaset vshard COMMAND {APPLICATION[:APP_INSTANCE] | URI} [OPTIONS ...]
# or
$ tt rs vshard COMMAND {APPLICATION[:APP_INSTANCE] | URI} [OPTIONS ...]
# or
$ tt rs vs COMMAND {APPLICATION[:APP_INSTANCE] | URI} [OPTIONS ...]

tt replicaset vshard (tt rs vs) manages vshard in the cluster.

It has the following subcommands:

vshard bootstrap

$ tt replicaset vshard bootstrap {APPLICATION[:APP_INSTANCE] | URI} [OPTIONS ...]
# or
$ tt rs vshard bootstrap {APPLICATION[:APP_INSTANCE] | URI} [OPTIONS ...]
# or
$ tt rs vs bootstrap {APPLICATION[:APP_INSTANCE] | URI} [OPTIONS ...]

tt replicaset vshard bootstrap (tt rs vs bootstrap) bootstraps vshard in the cluster.

$ tt replicaset vshard bootstrap myapp

With a URI and credentials:

$ tt replicaset vshard bootstrap 192.168.10.10:3301 -u myuser -p p4$$w0rD

You can specify the application name or the name of any cluster instance. The command automatically finds a vshard router in the cluster and calls vshard.router.bootstrap() on it.

The command supports the --config, --cartridge, and --custom options that force the use of a specific orchestrator.

To bootstrap vshard in a Cartridge cluster:

$ tt replicaset vshard bootstrap my-cartridge-app --cartridge

bootstrap

Важно

The Tarantool Cartridge framework is deprecated and is not compatible with Tarantool 3.0 and later. This command is added for backward compatibility with earlier versions.

$ tt replicaset bootstrap APPLICATION[:APP_INSTANCE] [OPTIONS ...]
# or
$ tt rs bootstrap APPLICATION[:APP_INSTANCE] [OPTIONS ...]

tt replicaset bootstrap (tt rs bootstrap) bootstraps a Cartridge cluster or an instance. The command works within the current tt environment and uses application and instance names.

Примечание

tt replicasets bootstrap effectively duplicates two other commands:

Bootstrapping a Cartridge cluster

To bootstrap the cartridge_app application using its default replica sets file replicasets.yml:

$ tt replicaset bootstrap cartridge_app

To use another file with replica set configuration, provide a path to it in the --file option:

$ tt replicaset bootstrap cartridge_app --file replicasets1.yml

To additionally bootstrap vshard after the cluster bootstrap, add --bootstrap-vshard:

$ tt replicaset bootstrap --bootstrap-vshard cartridge_app

Bootstrapping an instance

When called with the instance name, tt replicaset bootstrap joins the instance to the replica set specified in the --replicaset option:

$ tt replicaset bootstrap --replicaset replicaset cartridge_app:instance1

rebootstrap

$ tt replicaset rebootstrap APPLICATION:APP_INSTANCE [-y | --yes]
# or
$ tt rs rebootstrap APPLICATION:APP_INSTANCE [-y | --yes]

tt replicaset rebootstrap (tt rs rebootstrap) rebootstraps an instance: stops it, removes instance artifacts, starts it again.

To rebootstrap the storage-001 instance of the myapp application:

$ tt replicaset rebootstrap myapp:storage-001

To automatically confirm reboostrap, add the -y/--yes option:

$ tt replicaset rebootstrap myapp:storage-001 -y

Selecting the application orchestrator manually

You can specify the orchestrator to use for the application when calling tt replicaset commands. The following options are available:

$ tt replicaset status myapp --config
$ tt replicaset promote my-cartridge-app:storage-001-a --cartridge

If an actual orchestrator that the application uses does not match the specified option, an error is raised.

Authentication

Use one of the following ways to pass the credentials of a Tarantool user when connecting to the instance by its URI:

Options

--bootstrap-vshard

Applicable to: bootstrap

Additionally bootstrap vshard when bootstrapping a Cartridge application.

--cartridge

Force the Cartridge orchestrator for Tarantool 2.x clusters.

--config

Force the YAML configuration orchestrator for Tarantool 3.0 or later clusters.

--custom

Force a custom orchestrator for Tarantool 2.x clusters.

--file FILE

Applicable to: bootstrap

A file with Cartridge replica sets configuration. Default: instances.yml in the application directory.

See also: Bootstrapping a Cartridge cluster

-f, --force

Applicable to: promote, demote

Skip promotion or demotion if the specified instance is not running in the same environment.

--replicaset REPLICASET

Applicable to: bootstrap

A replica set name for instance bootstrapping.

See also: Bootstrapping an instance

-u USERNAME, --username USERNAME

A Tarantool user for connecting to the instance using a URI.

-p PASSWORD, --password PASSWORD

The user’s password.

--sslcertfile FILEPATH

The path to an SSL certificate file for encrypted connections for the URI case.

--sslkeyfile FILEPATH

The path to a private SSL key file for encrypted connections for the URI case.

--sslcafile FILEPATH

The path to a trusted certificate authorities (CA) file for encrypted connections for the URI case.

--sslciphers STRING

The list of SSL cipher suites used for encrypted connections for the URI case, separated by colons (:).

--timeout

Applicable to: promote, demote, expel, vshard, bootstrap

The timeout for completing the operation, in seconds. Default:

  • 3 for promote, demote, expel
  • 10 for vshard and bootstrap
-y, --yes

Applicable to: rebootstrap

Automatically confirm rebootstrap.

Restarting a Tarantool instance

$ tt restart APPLICATION[:APP_INSTANCE] [OPTION ...]

tt restart restarts the specified running Tarantool instance. A tt restart call is equivalent to consecutive calls of tt stop and tt start.

When called without arguments, restarts all running applications in the current environment.

See also: Starting Tarantool applications, Stopping a Tarantool instance, Checking instance status.

Options

-y, --yes

Automatic «Yes» to confirmation prompt.

Examples

Using the LuaRocks package manager

$ tt rocks [OPTION ...] [VAR=VALUE] COMMAND [ARGUMENT]

tt rocks provides means to manage Lua modules (rocks) via the LuaRocks package manager. tt uses its own LuaRocks installation connected to the Tarantool rocks repository.

Below are lists of supported LuaRocks flags and commands. For detailed information on their usage, refer to LuaRocks documentation.

Options

--dev

Enable the sub-repositories in rocks servers for rockspecs of in-development versions.

--server=SERVER

Fetch rocks/rockspecs from this server (takes priority over config file).

--only-server=SERVER

Fetch rocks/rockspecs from this server only (overrides any entries in the config file).

--only-sources=URL

Restrict downloads to paths matching the given URL.

--lua-dir=PREFIX

Specify which Lua installation to use

--lua-version=VERSION

Specify which Lua version to use.

--tree=TREE

Specify which tree to operate on.

--local

Use the tree in the user’s home directory. Call tt rocks help path to learn how to enable it.

--global

Use the system tree when local_by_default is true.

--verbose

Display verbose output for the command executed.

--timeout=SECONDS

Timeout on network operations, in seconds. 0 means no timeout (wait forever). Default: 30.

Commands

admin Use the luarocks-admin tool
build Build and compile a rock
config Query information about the LuaRocks configuration
doc Show documentation for an installed rock
download Download a specific rock file from a rocks server
help Help on commands. Type tt rocks help <command> for more
init Initialize a directory for a Lua project using LuaRocks
install Install a rock
lint Check syntax of a rockspec
list List the currently installed rocks
make Compile package in the current directory using a rockspec
make_manifest Compile a manifest file for a repository
new_version Auto-write a rockspec for a new version of a rock
pack Create a rock, packing sources or binaries
purge Remove all installed rocks from a tree
remove Uninstall a rock
search Query the LuaRocks servers
show Show information about an installed rock
test Run the test suite in the current directory
unpack Unpack the contents of a rock
which Tell which file corresponds to a given module name
write_rockspec Write a template for a rockspec file

Examples

Running code in a Tarantool instance

$ tt run [SCRIPT|-e EXPR] [OPTION ...]

tt run executes Lua code in a new Tarantool instance.

Options

-e EXPR, --evaluate EXPR

Execute the specified expression in a Tarantool instance.

-l LIB_NAME, --library LIB_NAME

Require the specified library.

-i, --interactive

Enter the interactive mode after the script execution.

-v, --version

Print the Tarantool version that is used for script execution.

Details

tt run executes arbitrary Lua code in a Tarantool instance. The code can be provided either in a Lua file, or in a string passed after the -e/--evaluate flag. When called without arguments or flags, tt run opens the Tarantool console.

If libraries are required for execution, pass their names after the -l/--library flag.

By default, a Tarantool instance started by tt run shuts down after code execution completes. To leave this instance running and continue working in its console, add the -i/--interactive flag.

Examples

Listing available Tarantool versions

$ tt search PROGRAM_NAME [OPTION ...]

tt search lists versions of Tarantool and tt that are available for installation. The possible values of PROGRAM_NAME are:

Примечание

For tarantool-ee, account credentials are required. Specify them in a file (see the ee section of the configuration file) or provide interactively.

Options

--debug

Applicable to: tarantool-ee

Search for debug builds of Tarantool Enterprise Edition’s SDK.

--local-repo

Search in the local repository, which is specified in the repo section of the tt configuration file.

--version VERSION

Applicable to: tarantool-ee

Tarantool Enterprise version.

Example

Starting Tarantool applications

$ tt start [APPLICATION[:APP_INSTANCE]]

tt start starts Tarantool applications. The application files must be stored inside the instances_enabled directory specified in the tt configuration file. For detailed instructions on preparing and running Tarantool applications, see Application environment and Starting and stopping instances.

See also: Stopping a Tarantool instance, Restarting a Tarantool instance, Checking instance status.

To start all instances of the application stored in the app directory inside instances_enabled in accordance with its instances.yml:

$ tt start app

To start all instances of the app application appending their logs to stdout (in the interactive mode):

$ tt start -i app

To start the router instance of the app application:

$ tt start app:router

When called without arguments, starts all enabled applications in the current environment:

$ tt start

Application layout

tt start can start entire Tarantool clusters based on their YAML configurations. A cluster application directory inside instances_enabled must contain the following files:

For more information about Tarantool application layout, see Application environment.

Примечание

tt also supports Tarantool applications with configuration in code, which is considered a legacy approach since Tarantool 3.0. For information about using tt with such applications, refer to the Tarantool 2.11 documentation.

Running in the background

tt start runs Tarantool applications in the background and uses its own watchdog process for status checks (tt status) and application stopping (tt stop).

Важно

Do not switch on the background mode using the cluster configuration (process.background: true in the YAML configuration) or code (box.cfg.background = true) in applications that you run with tt. If you start such an application with tt start, tt won’t be able to check the application status or stop it using the corresponding commands.

Integrity check

Enterprise Edition

The integrity check functionality is supported by the Enterprise Edition only.

tt start can perform initial and periodical integrity checks of the environment, application, and centralized configuration.

To enable integrity checks of environment and application files, you need to pack the application using tt pack with the --with-integrity-check option. This option generates and signs checksums of executables and configuration files in the current tt environment. Learn more in Generating files for integrity checks.

To enable integrity check of the configuration at the centralized storage, publish the configuration to this storage using tt cluster publish with the --with-integrity-check option. This option generates and signs configuration checksums and saves them to the storage. Learn more in Publishing configurations with integrity check.

To perform the integrity checks when running the application, start it with the --integrity-check global option. Its argument must be a public key matching the private key that was used for generating checksums.

$ tt --integrity-check public.pem start myapp

After such a call, tt checks the environment, application, and configuration integrity using the checksums and starts the application in case of the success. Then, integrity checks are performed periodically while the application is running. By default, they are performed once every 24 hours. You can adjust the integrity check period by adding the --integrity-check-period option:

$ tt --integrity-check public.pem start myapp --integrity-check-period 60

Additionally, Tarantool checks the integrity of the modules that the application uses at the load time, that is, when require('module') is called.

If an integrity check fails, tt stops the application.

Options

-i, --interactive

Start the application or instance in the interactive mode. In this mode, instance logs are printed to the standard output in real time.

You can use the SIGINT signal (CTRL+C) to stop tt and its child Tarantool processes in the interactive mode. No watchdog processes are created.

--integrity-check-interval NUMBER

Integrity check interval in seconds. Default: 86400 (24 hours). Set this option to 0 to disable periodic checks.

See also: Integrity check

Checking instance status

$ tt status [APPLICATION[:APP_INSTANCE]] [-p|--pretty]

tt status prints the information about Tarantool applications and instances in the current environment. This includes:

When called without arguments, prints the status of all enabled applications in the current environment.

Examples

Options

-p, --pretty

Print the status as a pretty-formatted table.

Stopping a Tarantool instance

$ tt stop [APPLICATION[:APP_INSTANCE]]

tt stop stops the specified running Tarantool applications or instances. When called without arguments, stops all running applications in the current environment.

See also: Starting Tarantool applications, Restarting a Tarantool instance, Checking instance status.

Examples

Interacting with the Tarantool Data Grid 2

Enterprise Edition

This command is supported by the Enterprise Edition only.

$ tt tdg2 COMMAND [COMMAND_OPTION ...]

tt tdg2 enables the interaction with Tarantool Data Grid 2 clusters. COMMAND is one of the following:

Uninstalling Tarantool software

$ tt uninstall PROGRAM_NAME [VERSION]

tt uninstall uninstalls a previously installed Tarantool version.

Example

Uninstall Tarantool 2.10.4:

$ tt uninstall tarantool 2.10.4

Displaying the tt version

$ tt version

tt version shows the version of the tt utility being used.

Extending the tt functionality

The tt utility implements a modular architecture: its commands are, in fact, separate modules. When you run tt with a command, the corresponding module is executed with the given arguments.

The modular architecture enables the option to extend the tt functionality with external modules (as opposed to internal modules that implement built-in commands). Simply said, you can write any code you want to execute from tt, pack it into an executable, and run it with a tt command:

tt my-module-name my-args

The name of the command that executes a module is the same as the name of the module’s executable.

Module description and help

Executables that implement external tt modules must have two flags:

Location

External modules must be located in the modules directory specified in the configuration file:

tt:
  modules:
    directory: path/to/modules/dir

To check if a module is available in tt, call tt help. It will show the available external modules in the EXTERNAL COMMANDS section together with their descriptions.

Overloading built-in commands

External modules can overload built-in tt commands. If you want to change the behavior of a built-in command, create an external module with the same name and your own implementation.

When tt sees two modules – an external and an internal one – with the same name, it will use the external module by default.

For example, if you want tt to show the information about your Tarantool application, write the external module version that outputs the information you need. The tt version call will execute this module instead of the built-in one:

tt version # Calls the external module if it's available

You can force the use of the internal module by running tt with the --internal or -I option. The following call will execute the built-in version even if there is an external module with the same name:

tt version -I # Calls the internal module

tt interactive console

The tt utility features a command-line console that allows executing requests and Lua code interactively on the connected Tarantool instances. It is similar to the Tarantool interactive console with one key difference: the tt console allows connecting to any available instance, both local and remote. Additionally, it offers more flexible output formatting capabilities.

Entering the console

To connect to a Tarantool instance using the tt console, run tt connect.

Specify the instance URI and the user credentials in the corresponding options:

$ tt connect 192.168.10.10:3301 -u myuser -p p4$$w0rD
   • Connecting to the instance...
   • Connected to 192.168.10.10:3301

192.168.10.10:3301>

If a user is not specified, the connection is established on behalf of the guest user.

If the instance runs in the same tt environment, you can establish a local connection with it by specifying the <application>:<instance> string instead of the URI:

$ tt connect app:storage001
    • Connecting to the instance...
    • Connected to app:storage001

 app:storage001>

Local connections are established on behalf of the admin user.

To get the list of supported console commands, enter \help or ?. To quit the console, enter \quit or \q.

Console input

Similarly to the Tarantool interactive console, the tt console can handle Lua or SQL input. The default is Lua. For Lua input, the tab-based autocompletion works automatically for loaded modules.

To change the input language to SQL, run \set language sql:

app:storage001> \set language sql
app:storage001> select * from bands where id = 1
---
- metadata:
  - name: id
    type: unsigned
  - name: band_name
    type: string
  - name: year
    type: unsigned
  rows:
  - [1, 'Roxette', 1986]
...

To change the input language back to Lua, run \set language lua:

app:storage001> \set language lua
app:storage001> box.space.bands:select { 1 }
---
- - [1, 'Roxette', 1986]
...

Примечание

You can also specify the input language in the tt connect call using the -l/--language option:

$ tt connect app:storage001 -l sql

Console output

By default, the tt console prints the output data in the YAML format, each tuple on the new line:

app:storage001> box.space.bands:select { }
---
- - [1, 'Roxette', 1986]
  - [2, 'Scorpions', 1965]
  - [3, 'Ace of Base', 1987]
...

You can switch to alternative output formats – Lua or ASCII (pseudographics) tables – using the \set output console command:

app:storage001> \set output lua
app:storage001> box.space.bands:select { }
{{1, "Roxette", 1986}, {2, "Scorpions", 1965}, {3, "Ace of Base", 1987}};
app:storage001> \set output table
app:storage001> box.space.bands:select { }
+------+-------------+------+
| id   | band_name   | year |
+------+-------------+------+
| 1    | Roxette     | 1986 |
+------+-------------+------+
| 2    | Scorpions   | 1965 |
+------+-------------+------+
| 3    | Ace of Base | 1987 |
+------+-------------+------+

Примечание

Field names are printed since Tarantool 3.2. On earlier versions, actual names are replaced by numbered placeholders col1, col2, and so on.

The table output can be printed in the transposed format, where an object’s fields are arranged in columns instead of rows:

app:storage001> \set output ttable
app:storage001> box.space.bands:select { }
+-----------+---------+-----------+-------------+
| id        | 1       | 2         | 3           |
+-----------+---------+-----------+-------------+
| band_name | Roxette | Scorpions | Ace of Base |
+-----------+---------+-----------+-------------+
| year      | 1986    | 1965      | 1987        |
+-----------+---------+-----------+-------------+

Примечание

You can also specify the output format in the tt connect call using the -x/--outputformat option:

$ tt connect app:storage001 -x table

For table and ttable output, more customizations are possible with the following commands:

Commands

\help, ?

Show help on the tt console.

\quit, \q

Quit the tt console.

\shortcuts

Show available keyboard shortcuts.

\set language {lua|sql}

Set the input language. Possible values:

  • lua (default)
  • sql

An analog of the tt connect option -l/--language.

\set output FORMAT, \x{l|t|T|y}, \x

Set the output format. Possible FORMAT values:

  • yaml (default) – each output item is a YAML object. Example: [1, 'Roxette', 1986]. Shorthand: \xy.
  • lua – each output tuple is a separate Lua table. Example: {{1, "Roxette", 1986}};. Shorthand: \xl.
  • table – the output is a table where tuples are rows. Shorthand: \xt.
  • ttable – the output is a transposed table where tuples are columns. Shorthand: \xT.

Примечание

The \x command switches the output format cyclically in the order yaml > lua > table > ttable.

The format of table and ttable output can be adjusted using the \set table_format, \set graphics, and \set table_colum_width commands.

An analog of the tt connect option -x/--outputformat.

\set table_format

Set the table format if the output format is table or ttable. Possible values:

  • default – a pseudographics (ASCII) table.
  • markdown – a table in the Markdown format.
  • jira – a Jira-compatible table.

\set graphics {true|false}, \x{g|G}

Whether to print pseudographics for table cells if the output format is table or ttable. Possible values: true (default) and false.

The shorthands are:

  • \xG for true
  • \xg for false

\set table_colum_width WIDTH, \xw WIDTH

Set the maximum printed width of a table cell content. If the length exceeds this value, it continues on the next line starting from the + (plus) sign.

Shorthand: \xw

Migration from tarantoolctl to tt

tt is a command-line utility for managing Tarantool applications that comes to replace tarantoolctl. Starting from version 3.0, tarantoolctl is no longer shipped as a part of Tarantool distribution; tt is the only recommended tool for managing Tarantool applications from the command line.

tarantoolctl remains fully compatible with Tarantool 2.* versions. However, it doesn’t receive major updates anymore.

We recommend that you migrate from tarantoolctl to tt to ensure the full support and timely updates and fixes.

System-wide configuration

tt supports system-wide environment configuration by default. If you have Tarantool instances managed by tarantoolctl in such an environment, you can switch to tt without additional migration steps or use tt along with tarantoolctl.

Example:

$ sudo tt instances
List of enabled applications:
• example

$ tarantoolctl start example
Starting instance example...
Forwarding to 'systemctl start tarantool@example'

$ tarantoolctl status example
Forwarding to 'systemctl status tarantool@example'
● tarantool@example.service - Tarantool Database Server
    Loaded: loaded (/lib/systemd/system/tarantool@.service; enabled; vendor preset: enabled)
    Active: active (running)
    Docs: man:tarantool(1)
    Main PID: 6698 (tarantool)
. . .

$ sudo tt status
• example: RUNNING. PID: 6698.

$ sudo tt connect example
• Connecting to the instance...
• Connected to /var/run/tarantool/example.control

/var/run/tarantool/example.control>

$ sudo tt stop example
• The Instance example (PID = 6698) has been terminated.

$ tarantoolctl status example
Forwarding to 'systemctl status tarantool@example'
○ tarantool@example.service - Tarantool Database Server
    Loaded: loaded (/lib/systemd/system/tarantool@.service; enabled; vendor preset: enabled)
    Active: inactive (dead)

Local configuration

If you have a local tarantoolctl configuration, create a tt environment based on the existing .tarantoolctl configuration file. To do this, run tt init in the directory where the file is located.

Example:

$ cat .tarantoolctl
default_cfg = {
    pid_file  = "./run/tarantool",
    wal_dir   = "./lib/tarantool",
    memtx_dir = "./lib/tarantool",
    vinyl_dir = "./lib/tarantool",
    log       = "./log/tarantool",
    language  = "Lua",
}
instance_dir = "./instances.enabled"

$ tt init
• Found existing config '.tarantoolctl'
• Environment config is written to 'tt.yaml'

After that, you can start managing Tarantool instances in this environment with tt:

$ tt start app1
• Starting an instance [app1]...

$ tt status app1
• app1: RUNNING. PID: 33837.

$ tt stop app1
• The Instance app1 (PID = 33837) has been terminated.

$ tt check app1
• Result of check: syntax of file '/home/user/instances.enabled/app1.lua' is OK

Commands difference

Most tarantoolctl commands look the same in tt: tarantoolctl start and tt start, tarantoolctl play and tt play, and so on. To migrate such calls, it is usually enough to replace the utility name. There can be slight differences in command flags and format. For details on tt commands, see the tt commands reference.

The following commands are different in tt:

tarantoolctl command tt command
tarantoolctl enter tt connect
tarantoolctl eval tt connect with -f flag

Примечание

tt connect also covers tarantoolctl connect with the same syntax.

Example:

 # tarantoolctl enter > tt connect
 $ tarantoolctl enter app1
 connected to unix/:./run/tarantool/app1.control
 unix/:./run/tarantool/app1.control>

 $ tt connect app1
 • Connecting to the instance...
 • Connected to /home/user/run/tarantool/app1/app1.control

 # tarantoolctl eval > tt connect -f
 $ tarantoolctl eval app1 eval.lua
 connected to unix/:./run/tarantool/app1.control
 ---
 - 42
 ...

$ tt connect app1 -f eval.lua
 ---
 - 42
 ...

 # tarantoolctl connect > tt connect
 $ tarantoolctl connect localhost:3301
 connected to localhost:3301
 localhost:3301>

 $ tt connect localhost:3301
 • Connecting to the instance...
 • Connected to localhost:3301

Tarantool Cluster Manager

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

Tarantool Cluster Manager (TCM) is a web-based visual tool for configuring, managing, and monitoring Tarantool EE clusters. It provides a GUI for working with clusters and individual instances, from monitoring their state to executing commands interactively in an instance’s console.

TCM is a standalone application included in the Tarantool Enterprise Edition distribution package. It is shipped as ready-to-run executable for Linux platforms.

TCM works only with Tarantool EE clusters that use centralized configuration in etcd or a Tarantool-based configuration storage. When you create or edit a cluster’s configuration in TCM, it publishes the saved configuration to the storage. This ensures consistent and reliable configuration storage. A single TCM installation can connect to multiple Tarantool EE clusters and switch between them in one click.

To provide enterprise-grade security, TCM features its own role-based access control. You can create users and assign them roles that include required permissions. For example, a user can be an administrator of a specific cluster or only have the right to read data. LDAP authorization is supported as well.

Web interface overview

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

The Tarantool Cluster Manager web interface is available on the hostname and port defined by the http.host and http.port configuration options. If TLS is enabled, it uses the https protocol, otherwise the protocol is http. When started locally with the default configuration, TCM is available at http://127.0.0.1:8080.

Logging into TCM

To log into TCM after bootstrap, use the following credentials:

TCM login page

After logging in with the default password:

  1. Adjust the password policy in accordance to the security requirements that apply in your organization.
  2. Change the admin user’s password on the User settings page.

To log out of TCM, click the user’s name in the header and click Log out.

Page structure

The TCM web interface consists of three parts:

  1. Navigation page on the left shows the list of pages available to the user. The navigation pane can be collapsed by clicking the cross icon at its top.
  2. Header at the top provides access to notifications and user settings.
  3. Working area displays the contents of the selected page.
TCM UI parts: navigation pane, header, working area

Onboarding

The Onboarding item of the navigation pane starts the interactive onboarding tutorial. Use it to get familiar with main TCM features directly in the web interface.

Page visibility

This overview describes most TCM pages. The exact set of pages and controls available to a particular are determined by the user’s permissions.

Some features, such as data schema editing, are available only in the development mode. You can switch to it in the user settings of the Default Admin user.

Page groups

For easier navigation, TCM pages are grouped in the navigation pane by their content. There are the following page groups:

Read on to learn what you can do on pages of these groups.

Cluster

The Cluster group includes pages used for interaction with a particular cluster. To switch between clusters, click the Cluster group name and select a connected cluster from the drop-down list.

Stateboard

The cluster Stateboard is a main page for monitoring the cluster state and interacting with its instances.

TCM stateboard

On this page, you can:

  • view and edit the cluster topology
  • group and filter instances based on various criteria
  • view memory statistics and Tarantool versions running on instances
  • navigate to instance pages by clicking instance names in the cluster topology list
  • start and stop instances (in the development mode).

Learn more about using the cluster stateboard in Viewing cluster state.

Instance page

The instance page opens when you click an instance name on the Stateboard.

TCM instance page

It provides a set of tabs for performing actions on the selected Tarantool instance:

  • Details and State tabs: view instance details as a human-readable table or as a console output of box.cfg, box.info, and other built-in functions
  • SQL and Terminal tabs: run SQL and Lua commands on the instance
  • Logs tab: view instance logs
  • Slabs tab: view slab allocator statistics
  • Users tab: manage Tarantool users and roles on the instance
  • Funcs: manage and call stored functions
  • Metrics: view instance metrics

The instance page has an Actions menu at the top that allows you to:

  • navigate to the instance explorer
  • edit the instance configuration
  • remove the instance

Configuration

The cluster Configuration page provides an interactive editor for the cluster configuration. It is connected to the centralized configuration storage that the cluster uses. All changes you make and apply on this page are sent to this centralized storage.

TCM cluster configuration page

Learn more in Configuring clusters.

Security

The Security page provides controls for managing the cluster security settings.

TCM cluster security page

Learn more in Security settings.

Migrations

The Migrations page provides centralized migration management tools for the selected cluster.

TCM cluster migrations page

Learn more in Performing migrations.

Tuples

Важно

The cluster-wide access to stored data on the Tuples page is supported only for sharded clusters that use the CRUD module.

The Tuples page provides access to data stored in user spaces of the selected cluster.

TCM tuples page

On this page, you can:

  • view the list of user spaces, their size and engines
  • view and edit tuples stored in user spaces

TCF

The TCF page provides an interface for clusters that run within Tarantool Clusters Federation.

TCM TCF page

On this page, you can:

  • view information about TCF clusters
  • switch cluster states in a TCF installation

Learn more in TCF integration.

Cluster metrics

The Cluster metrics page provides access to the selected cluster’s metrics.

TCM cluster metrics page

Learn more in Viewing cluster metrics.

Instance explorer

The instance Explorer provides access to all spaces of a specific instance, including system spaces.

TCM instance explorer

On this page, you can:

  • view and edit instance spaces, their size and engines
  • view and edit tuples stored in all spaces of the instance

Clusters

The Clusters group includes pages used for managing TCM’s cluster connections.

Clusters

The Clusters page lists Tarantool clusters that are connected to TCM.

TCM clusters page

On this page, you can:

  • connect Tarantool clusters to TCM
  • edit cluster connections
  • disconnect clusters

Learn more in Connecting clusters.

ACL

The ACL page displays the TCM access control list.

TCM ACL page

On this page, you can add and delete ACL entries. Learn more in Access control list.

Users

The Users group includes pages related to user access to TCM.

Users

The Users page lists TCM users.

TCM users page

On this page, you can:

  • add, edit, and delete users
  • manage user secrets (passwords and API tokens)
  • revoke user sessions

Learn more in Users.

Roles

The Roles page lists TCM user roles.

TCM roles page

On this page, you can add, edit, and delete roles. Learn more in Roles.

Sessions

The Sessions page lists active sessions of TCM users.

TCM sessions page

On this page, you can view and revoke sessions. Learn more in Sessions.

Tools

The Tools group includes service pages used for TCM maintenance and monitoring.

Audit log

The Audit log page displays the TCM audit log.

TCM audit log

TCM metrics

The TCM metrics page provides access to the TCM metrics.

TCM metrics page

Settings

The Settings group includes service pages where you can configure various TCM features.

Password policy

On the Password policy page, you can configure the requirements to user passwords, such as minimal length, required symbols, expiration, and other settings. Learn more in Password policy.

TCM password policy

Audit settings

On the Audit settings page, you can configure how TCM records events to its audit log: whether audit log is enabled, which events are recorded, and so on. Learn more in Audit log.

TCM audit settings

LDAP

On the LDAP page, you can manage TCM LDAP configurations.

TCM LDAP configurations

User settings

The user settings dialog opens when you click Settings under the user’s name in the header.

TCM user settings

This dialog includes the following tabs:

Connecting clusters

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

Tarantool Cluster Manager works with clusters that:

A single TCM installation can have multiple connected clusters. A connection to TCM doesn’t affect the cluster’s functioning. You can connect clusters to TCM and disconnect them on the fly.

There are two ways to add a cluster to TCM:

In both cases, you need to deploy Tarantool and start the cluster instances using the tt CLI utility or another suitable way.

Connection parameters

When connecting a cluster to TCM, you need to provide two sets of connection parameters: for the cluster instances and for the centralized configuration storage.

Configuration storage connection

The cluster configuration can be stored in either an etcd cluster or a separate Tarantool-based storage. In both cases, the following connection parameters are required:

  • A key prefix used to identify the cluster in the configuration storage. A prefix must be unique for each cluster in storage.
  • URIs of all instances of the configuration storage.
  • The credentials for accessing the configuration storage: an etcd user or a Tarantool user.

Additionally, if SSL or TLS encryption is enabled for the configuration storage, provide the corresponding encryption configuration: keys, certificates, and other parameters. For the complete list of parameters, consult the etcd documentation or Tarantool Securing connections with SSL.

Cluster connection

For interaction with the cluster instances, TCM needs the following access parameters:

  • A Tarantool user that exists in the cluster and their password. TCM connects to the cluster on behalf of this user.
  • An SSL configuration if the traffic encryption is enabled on the cluster.

Managing connected clusters

Administrators can add new clusters, edit, and remove existing ones from TCM.

Connected clusters are listed on the Clusters page.

Connecting a pre-configured cluster

If you already have a cluster and want to connect it to TCM, follow these steps:

  1. Go to Clusters and click Add.
  2. Fill in the general cluster information:
    • Specify an arbitrary name.
    • Optionally, provide a description and select a color to mark this cluster in TCM.
    • Optionally, enter the URLs of additional services for the cluster. For example, a Grafana dashboard that monitors the cluster metrics, or a syslog server for viewing the cluster logs. TCM provides quick access to these URLs on the cluster Stateboard page.
  1. Provide the details of the cluster configuration storage:
    • Storage type: etcd or tarantool.
    • The Prefix specified in the cluster configuration.
    • The URIs of the configuration storage instances.
    • The credentials for accessing the configuration storage.
    • The SSL/TLS parameters if the connection encryption is enabled on the storage.
  2. Provide the credentials for accessing the cluster: a Tarantool user’s name, their password, and SSL parameters in case traffic encryption is enabled on the cluster.

Adding a new cluster

If you don’t have a cluster yet, you can add one in TCM and write its configuration from scratch using the built-in configuration editor.

Важно

When adding a new cluster, you need to have a storage for its configuration up and running so that TCM can connect to it. Cluster instances can be deployed later.

To add a new cluster:

  1. Go to Clusters and click Add.
  2. Fill in the general cluster information:
    • Specify an arbitrary name.
    • Optionally, provide a description and select a color to mark this cluster in TCM.
    • Optionally, enter the URLs of additional services for the cluster. For example, a Grafana dashboard that monitors the cluster metrics, or a syslog server for viewing the cluster logs. TCM provides quick access to these URLs on the cluster Stateboard page.
  3. Select the type of the cluster configuration storage: etcd or tarantool.
  4. Define a unique Prefix for identifying this cluster in the configuration storage.
  5. Provide the connection details for the cluster configuration storage:
    • The URIs of configuration storage instances.
    • The credentials for accessing the configuration storage.
    • The SSL/TLS parameters if the connection encryption is enabled on the storage.
  6. Provide the cluster credentials: a username, a password, and SSL parameters in case traffic encryption is enabled on the cluster.

Once you add the cluster:

Editing a connected cluster

To edit a connected cluster, go to Clusters and click Edit in the Actions menu of the corresponding table row.

Disconnecting a cluster

To disconnect a cluster from TCM, go to Clusters and click Disconnect in the Actions menu of the corresponding table row.

Примечание

Disconnecting a cluster does not affect its functioning. The only thing that changes is that it’s no longer shown in TCM. You can connect this cluster again at any time.

Cluster management

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

The main goal of Tarantool Cluster Manager is to provide visual tools for managing various aspects of Tarantool clusters from the browser. See the pages of this section to learn how to perform various management operations on Tarantool clusters from TCM.

Viewing cluster state

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

Tarantool Cluster Manager provides a visual interface for checking various aspects of connected clusters, such as:

Cluster state information is available on the Cluster > Stateboard page.

Cluster topology

The cluster topology is displayed on the Stateboard page in one of two forms: a list or a graph.

List view

The list view of the cluster topology is used by default. In this view, each row contains the general information about an instance: its current state, memory usage and limit, and other parameters.

In the list view, TCM additionally displays the Tarantool version information and instance states on circle diagrams. You can click the sectors of these diagrams to filter the instances with the selected versions and states.

To switch to the list view, click the list button on the right of the search bar on the Stateboard page.

Graph view

The graph view of the cluster topology is shown in a tree-like structure where leafs are the cluster’s instances. Each instance’s state is shown by its color. You can move the graph vertices to arrange them as you like, and zoom in and out, which is helpful for larger clusters.

To switch to the graph view, click the graph button on the right of the search bar on the Stateboard page.

Instance grouping

By default, the cluster topology is shown hierarchically as it’s defined in the configuration: instances are grouped by their replica set, and replica sets are grouped by their configuration group.

For better navigation across the cluster, you can adjust the instance grouping. For example, you can group instances by their roles or custom tags defined in the configuration. A typical case for such tags is adding a geographical markers to instances. In this case, you see if issues happen in a specific data center or server.

To change the instance grouping, click Group by in the Actions menu on the Stateboard page. Then add or remove grouping criteria.

Filtering

You can filter the instances shown on the Stateboard page using the search bar at the top. It has predefined filters that select:

  • instances with errors or warnings
  • leader or read-only instances
  • instances with no issues
  • stale instances

To display all instances, delete the filter applied in the search bar.

Instance details

The general information about the state of cluster instances is shown in the list view of the cluster topology. Each row contains the information about the instance status, used and available memory, read-only status, and virtual buckets for sharded clusters.

To view the detailed information about an instance or connect to it, click the corresponding row in the instances list or a vertex of the graph. On the instance page, you can find:

Additionally, on the instance details page there is a terminal in which you can execute arbitrary Lua code on the instance.

Linked external services

When you connect a cluster to TCM, you can specify URLs of external services linked to this cluster. For example, this can be a Grafana server that monitors the cluster metrics.

All the URLs added for a cluster are available for quick access in the Actions menu on the Stateboard page.

Configuring clusters

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

Tarantool Cluster Manager features a built-in text editor for Tarantool EE cluster configurations.

When you connect a cluster to TCM, it gains access to the cluster’s centralized configuration storage: an etcd or a Tarantool cluster. TCM has both read and write access to the cluster configuration. This enables the configuration editor to work in two ways:

To learn how to write Tarantool cluster configurations, see Configuration.

Managing a cluster’s configuration

The configuration editor is available on the Cluster > Configuration page.

To start managing a cluster’s configuration, select this cluster in the Cluster drop-down and go to the Configuration page.

A cluster configuration in TCM can consist of one or multiple YAML files. When there are multiple files, they are all considered parts of a single cluster configuration. You can use this for structuring big cluster configurations. All files that form the configuration of a cluster are listed on the left side of the Cluster configuration page.

To add a cluster configuration file, click the plus icon (+) below the page title.

To open a configuration file in the editor, click its name in the file list.

To delete a cluster configuration file, click the Delete button beside the filename.

To download a cluster configuration file, click the Download button beside the filename.

Предупреждение

All configuration changes are discarded when you leave the Cluster configuration page. Save the configuration if you want to continue editing it later or apply it to start using it on the cluster.

Saving a configuration draft

TCM can store configurations drafts. If you want to leave an unfinished configuration and return to it later, save it in TCM. Saving applies to whole cluster configurations: it records the edits of all files, file additions, and file deletions.

To save a cluster configuration draft after editing, click Save in the Cluster configuration page.

All unsaved changes are discarded when you leave the Cluster configuration page.

If you have a saved configuration draft, you can reset the changes for each of its files individually. A reset returns the file into the state that is currently used by a cluster (that is, saved in the configuration storage). If you reset a newly added file, it is deleted.

To reset a saved configuration file, click the Reset button beside the filename.

Applying a configuration

When you finish editing a configuration and it’s ready to use, apply the updated configuration to the cluster. To apply a cluster configuration, click Apply on the Cluster configuration page. This sends the new configuration to the cluster configuration storage, and it comes into effect upon the cluster configuration reload.

Managing cluster users and roles

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

Tarantool Cluster Manager provides a visual interface for managing Tarantool users and roles on connected clusters.

Примечание

This page describes management of Tarantool users and roles on instances of connected clusters. To learn to manage TCM users, see Access control.

The Tarantool access model defines user access to entities inside a single instance. Thus, to create or alter a cluster-wide user or role, you need to do this on all cluster instances. In replication clusters, changes in access model are possible only on read-write instances (replica set leaders). Changes made on a leader instance are propagated to all instances of its replica set automatically.

Operations on the cluster access model are possible only if the user that TCM uses to connect to the cluster has the privileges to manage users and roles.

You can also manage Tarantool users and roles from TCM using the Lua API as described in Управление доступом. To do this, connect to instance consoles from the Terminal tab of the instance page.

Managing cluster users

The tools for managing cluster users are located on the Users tab of the instance page.

Важно

To ensure the access model consistency across the cluster, repeat all user management operations on all read-write instances of the cluster.

To create a user on a cluster:

  1. Go to Stateboard.
  2. Find a replica set leader in the instances list and click it to open the instance page.
  3. Go to the Users tab and click Add user.

To edit or delete a user, click the Edit or Delete button against the username in the Users table.

To edit a user’s privileges:

  1. Click the lock icon against the username in the Users table.
  2. In the privileges dialog:
    • Click Add to grant privileges
    • Click Revoke (the trash bin icon) to revoke a privilege

Managing cluster roles

The tools for managing cluster roles are located on the Users tab of the instance page.

Важно

To ensure the access model consistency across the cluster, repeat all role management operations on all read-write instances of the cluster.

To create a role on a cluster:

  1. Go to Stateboard.
  2. Find a replica set leader in the instances list and click it to open the instance page.
  3. Go to the Users tab and click Add role.

To delete a role, click the Delete button against the role name in the Roles table.

To edit a role’s privileges:

  1. Click the lock icon against the role name in the Roles table.
  2. In the privileges dialog:
    • Click Add to grant privileges
    • Click Revoke (the trash bin icon) to revoke a privilege

Security settings

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

Tarantool Cluster Manager includes a web interface for managing security settings of connected clusters. It is available on the Cluster > Security page. On this page, you can manage the following security features in the cluster:

Viewing cluster metrics

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

In Tarantool Cluster Manager, you can view metrics of connected clusters in real time on the Cluster > Cluster metrics page. The list of metrics that Tarantool exposes is provided in the Metrics reference.

Metrics are displayed one by one. To view a metric, select it in the drop-down list at the top of the page. Then, choose a way to visualize it:

Once you select a metric, TCM starts visualizing its current values, updating them once per second. To pause the visualization, click the button on the left from the metrics selector. To stop the visualization, clear the metric selection.

Viewing instance metrics

To view metrics of a specific instance, find this instance on the Stateboard, click its name, and go to the Metrics tab of the instance page.

Monitoring metrics with Prometheus

To allow collecting cluster metrics with external systems, such as Prometheus, TCM provides HTTP endpoints at /api/metrics/<clusterId>.

Примечание

Cluster IDs are shown in the cluster selection dialog that opens when you click Cluster at the top of the left navigation pane.

To access such an endpoint, a request must be authorized with an API token that has a cluster.metrics permission on the target cluster.

Below is an example of a Prometheus scrape configuration that collects metrics of a Tarantool cluster from TCM:

- job_name: "tarantool"
    static_configs:
      - targets: ["127.0.0.1:8080"]
    metrics_path: "/api/metrics/00000000-0000-0000-0000-000000000000"
    bearer_token: QgMPZ22JZ3uw7n0QTbqYGAQDmNDs1JnTkhaC1OlQzWM3utmpV78b23GG97zp8YE3

Using supervised failover

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

For Tarantool clusters that use supervised failover, Tarantool Cluster Manager offers tools for interaction with external failover coordinators from its web interface.

The tools for using supervised failover are located on the Failovers page available from the Actions menu on the cluster stateboard.

Примечание

TCM can interact with failover coordinators that are already running. There is no way to start or stop coordinators from TCM.

Viewing failover coordinators

To view failover coordinators running on the cluster, go to the Failovers tab. On this tab, you can see the information about all Tarantool instances that the cluster uses as failover coordinators. The information includes:

Executing failover commands

To send a failover command to a coordinator, go to the Commands tab and click Add. Then, provide the command description in the YAML format. It can include the following fields:

Example:

command: switch
new_master: instance-002
timeout: 30

After entering the command, click Save to send the command for execution.

Tarantool assigns an id to the command and waits for the active coordinator to process the command.

All failover commands executed on the cluster are shown on the Commands tab with their ids and statuses. A command can have the following statuses:

To see the command execution details, click this command in the list.

Performing migrations

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

Tarantool Cluster Manager provides a web interface for managing and performing migrations in connected clusters. To learn more about migrations in Tarantool, see Migrations.

Migrations are named Lua files with code that alters the cluster data schema, for example, creates a space, changes its format, or adds indexes. In TCM, there is a dedicated page where you can organize migrations, edit their code, and apply them to the cluster.

Managing migrations

The tools for managing migrations from TCM are located on the Cluster > Migrations page.

To create a migration:

  1. Click Add (the + icon) on the Migrations page.

  2. Enter the migration name.

    Важно

    When naming migrations, remember that they are applied in the lexicographical order. Use ordered numbers as filename prefixes to define the migrations order. For example, 001_create_table, 002_add_column, 003_create_index.

  3. Write the migration code in the editor window. Use the box.schema module reference to learn how to work with Tarantool data schema.

Once you complete writing the migration, save it by clicking Save. This saves the migration that is currently opened in the editor.

Appliyng migrations

After you prepare a set of migrations, apply it to the cluster. To apply all saved migrations to the cluster at once, click Apply.

Важно

Applying all saved migrations at once, in the lexicographical order is the only way to apply migrations in TCM. There is no way to select a single or several migrations to apply. The migrations that are already applied are skipped. To learn how to check a migration status, see Checking migrations status.

Migrations that were created but not saved yet are not applied when you click Apply.

Checking migrations status

To check the migration results on the cluster, use the Migrated widget on the cluster stateboard. It reflects the general result of the last applied migration set:

Hovering a cursor over the widget shows the number of instances on which the currently saved migration set is successfully applied.

You can also check the status of each particular migration on the Migrations page. The migrations that are successfully applied are marked with green check marks. Failed migrations are marked with exclamation mark icons (!). Hover the cursor over the icon to see the information about the error. To reapply a failed migration, click Force apply in the pop-up with the error information.

Migration file example

The following migration code creates a formatted space with two indexes in a sharded cluster:

local function apply_scenario()
    local space = box.schema.space.create('customers')

    space:format {
        { name = 'id',        type = 'number' },
        { name = 'bucket_id', type = 'number' },
        { name = 'name',      type = 'string' },
    }

    space:create_index('primary', { parts = { 'id' } })
    space:create_index('bucket_id', { parts = { 'bucket_id' }, unique = false })
end

return {
    apply = {
        scenario = apply_scenario,
    },
}

TCF integration

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

Tarantool Cluster Manager provides a web interface for clusters that run within Tarantool Clusters Federation. It is available on the Cluster > TCF page. If a connected cluster is configured to run in a TCF installation, this page shows information about both clusters in this installation: their ID’s, names, and statuses. To switch cluster states in TCF, click Toggle on the TCF page.

To learn more about Tarantool Clusters Federation, see its documentation.

Примечание

For individual clusters, the TCF page is empty.

Accessing cluster data

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

Tarantool Cluster Manager provides access to data stored in connected clusters through its web interface. You can view, add, edit, and delete tuples from spaces.

Примечание

A TCM user’s access to specific clusters and spaces is determined by their cluster permissions and access control list.

Data access is implemented in TCM on a per-instance basis: you can access data stored on one cluster instance at a time. For sharded clusters that use the CRUD module, it’s also possible to access data throughout the whole cluster.

Instance data

There are the following ways to access data stored on a cluster instance from TCM:

Важно

Data modification is possible only on instances in the read-write mode (replica set leaders). Changes are applied to read-only replicas in accordance with the cluster topology.

Instance explorer

The instance explorer provides access to all spaces that exist on the instances in the web interface. This includes both system and user spaces.

To open the instance explorer:

  1. Go to Stateboard.
  2. Click the instance row in the instances list or its graph vertex in the graph view.
  3. Click Explorer in the Actions menu of the instance details page.

To view tuples of a space, click its row in the spaces list.

To add a new tuple, click + on the space page and provide tuple field values in the Lua format, for example, [ 1, 1000, true, "test"].

To edit a tuple, click it in the table and then click Edit.

To delete a tuple, select it in the table and click Delete (the trash bin button).

In the development mode, you can also create, edit, truncate, and delete spaces in the instance explorer. To create a space, click Add and follow the wizard steps. To edit, truncate, or remove a space, click the corresponding button in the Actions menu of the space row in the table.

SQL terminal

TCM features an SQL terminal that you can use to access stored data. It is located on the SQL tab of the instance details page. In the SQL terminal, you can execute any supported SQL expressions on the selected instance.

For select SQL queries, you can also download the query result set in the CSV format.

To learn more about using SQL in Tarantool, see the SQL tutorial.

Lua API: Tarantool and tt consoles

TCM provides interactive access to instances“ consoles on the Terminal tab of the instance details page. You can choose between the tt console (TT Connect tab) and Tarantool interactive console (Direct tab).

In these consoles, you can access the stored data using the Tarantool Lua API.

Sharded cluster data

For sharded clusters that use the CRUD module, it’s possible to access stored data throughout the cluster on the Cluster > Tuples page. This page displays only user spaces.

To view all tuples of a space in a sharded cluster, click the space row in the list.

To add a new tuple, click + on the space page and provide tuple field values in the Lua format, for example [ 1, 1000, true, "test"]. When you add a tuple in a sharded cluster, it is distributed to a replica set based on the sharding key (the bucket_id field) value.

To edit a tuple, click it in the table and then click Edit.

To delete a tuple, select it in the table and click Delete (the trash bin button).

Creating spaces in sharded clusters

To create a space in a sharded cluster, create it on all read-write cluster instances on their Instance explorer pages.

Важно

Sharded spaces must include the bucket_id field of the unsigned type and a non-unique index by this field with the same name.

To edit, truncate, or delete spaces in a sharded cluster, perform the corresponding action on all read-write cluster instances.

Access control

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

Tarantool Cluster Manager provides means for managing user and client applications access to its own functions and connected clusters:

Role-based access control

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

Tarantool Cluster Manager features a role-based access control system. It enables flexible management of access to TCM functions, connected clusters, and stored data. The TCM access system uses three main entities: permissions, roles, and users (or user accounts). They work as follows:

Примечание

TCM users, roles, and permissions are not to be confused with similar subjects of the Tarantool access control system. To access Tarantool instances directly, Tarantool users with corresponding roles are required.

Permissions

Permissions define access to specific actions that users can do in TCM. For example, there are permissions to view connected clusters or to manage users.

There are two types of permissions in TCM: administrative and cluster permissions.

Permissions are predefined in TCM, there is no way to change, add, or delete them. The complete lists of administrative and cluster permissions in TCM are provided in the Permissions reference.

Roles

Roles are groups of administrative permissions that are assigned to users together.

The assigned roles define pages that users see in TCM and actions available on these pages.

Примечание

Roles don’t include cluster permissions. Access to connected clusters is configured for each user individually.

Default roles

TCM comes with default roles that cover three common usage scenarios:

  • Super Admin Role is a default role with all available administrative permissions. Additionally, the users with this role automatically gain all cluster permissions to all clusters.
  • Cluster Admin Role is a default role for cluster administration. It includes administrative permissions for cluster management.
  • Default User Role is a default role for working with clusters. It includes basic administrative read permissions that are required to log in to TCM and navigate to a cluster.

Managing roles

Administrators can create new roles, edit, and delete existing ones.

Roles are listed on the Roles page.

To create a new role, click Add, enter the role name, and select the permissions to include in the role.

To edit an existing role, click Edit in the Actions menu of the corresponding table row.

To delete a role, click Delete in the Actions menu of the corresponding table row.

Примечание

You can delete a role only if there are no users with this role.

Users

TCM users gain access to objects and actions through assigned roles and cluster permissions.

A user can have any number of roles or none of them. Users without roles have access only to clusters that are assigned to them.

TCM uses password authentication for users. For information on password management, see the Passwords section below.

Default admin

There is one default user Default Admin. It has all the available permissions, both administrative and cluster ones. When new clusters are added in TCM, Default Admin automatically receives all cluster permissions for them as well.

Managing users

Administrators can create new users, edit, and delete existing ones.

The tools for managing users are located on the Users page.

To create a user:

  1. Click Add.
  2. Fill in the user information: username, full name, and description.
  3. Generate or type in a password.
  4. Select roles to assign to the user.
  5. Add clusters to give the user access to, and select cluster permissions for each of them.

To edit a user, click Edit in the Actions menu of the corresponding table row.

To delete a user, click Delete in the Actions menu of the corresponding table row.

Passwords

TCM uses the general term secret for user authentication keys. A secret is any pair of a public and a private key that can be used for authentication. A password combined with a username is a secret type used for TCM user authentication. In this case, the public key is a username, and the private key is a password.

Users receive their first passwords during their account creation.

All passwords are governed by the password policy. It can be flexibly configured to follow the security requirements of your organization.

Changing your password

To change your own password, click your name in the top-right corner and go to Settings > Change password.

Changing users“ passwords

Administrators can manage a user’s password on this user’s Secrets page. To open it, click Secrets in the Actions menu of the corresponding Users table row.

To change a user’s password, click Edit in the Actions menu of the corresponding Secrets table row and enter the new password in the New secret key field.

Password expiry

Passwords expire automatically after the expiration period defined in the password policy. When a user logs in to TCM with an expired password, the only action available to them is a password change. All other TCM functions and objects are unavailable until the new password is set.

Administrators can also set users“ passwords to expired manually. To set a user’s password to expired, click Expire in the Actions menu of the corresponding Secrets table row.

Важно

Password expiration can’t be reverted.

Blocking passwords

To forbid users“ access to TCM, administrators can temporarily block their passwords. A blocked password can’t be used to log into TCM until it’s unblocked manually or the blocking period expires.

To block a user’s password, click Block in the Actions menu of the corresponding Secrets table row. Then provide a blocking reason and enter the blocking period.

To unblock a blocked password, click Unblock in the Actions menu of the corresponding Secrets table row.

Password policy

Password policy helps improve security and comply with security requirements that can apply to your organization.

You can edit the TCM password policy on the Password policy page. There are the following password policy settings:

  • Minimal password length.
  • Do not use last N passwords.
  • Password expiration in days. Users“ passwords expire after this number of days since they were set. Users with expired passwords lose access to any objects and functions except password change until they set a new password.
  • Password expiration warning in days. After this number of days, the user sees a warning that their password expires soon.
  • Block after N login attempts. Temporarily block users if they enter their username or password incorrectly this number of times consecutively.
  • User lockout time in seconds. The time interval for which users can’t log in after spending all failed login attempts.
  • Password must include. Characters and symbols that must be present in passwords:
    • Lowercase characters (a-z)
    • Uppercase characters (A-Z)
    • Digits (0-9)
    • Symbols (such as !@#$%^&*()_+№»“:,.;=][{}`?>/.)

Permissions reference

Administrative permissions

The following administrative permissions are available in TCM:

Permission Description
admin.clusters.read View connected clusters“ details
admin.clusters.write Edit cluster details and add new clusters
admin.users.read View users“ details
admin.users.write Edit user details and add new users
admin.roles.read View roles“ details
admin.roles.write Edit roles and add new roles
admin.addons.read View add-ons
admin.addons.write Edit add-on flags
admin.addons.upload Upload new add-ons
admin.auditlog.read View audit log configuration and read audit log in TCM
admin.auditlog.write Edit audit log configuration
admin.sessions.read View users“ sessions
admin.sessions.write Revoke users“ sessions
admin.ldap.read View LDAP configurations
admin.ldap.write Manage LDAP configurations
admin.passwordpolicy.read View password policy
admin.passwordpolicy.write Manage password policy
admin.secrets.read View information about users“ secrets
admin.secrets.write Manage users“ secrets: add, edit, expire, block, delete
user.password.change User’s permission to change their own password
user.api-token.read User’s permission to read their own API tokens information
user.api-token.write User’s permission to modify their own API tokens
admin.metrics Read TCM metrics
admin.acl.read View the access control list (ACL)
admin.acl.write Add and delete ACL entries

Cluster permissions

The following cluster permissions are available in TCM:

Permission Description
cluster.config.read View cluster configuration
cluster.config.write Manage cluster configuration
cluster.stateboard.read View cluster stateboard
cluster.func.read View cluster’s stored functions
cluster.func.write Edit cluster’s stored functions
cluster.func.call Execute stored functions on cluster instances
cluster.space.read Read cluster data schema
cluster.space.write Modify cluster data schema
cluster.space.data.read Read stored data from cluster
cluster.space.data.write Edit stored data on cluster
cluster.failover.read Read cluster failover information
cluster.failover.write Write cluster failover commands
cluster.terminal Connect to cluster instances with tt terminal from TCM
cluster.sql Execute SQL queries
cluster.metrics View cluster metrics

LDAP authentication

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

In addition to its internal role-based access control model, Tarantool Cluster Manager can use an external LDAP (Lightweight Directory Access Protocol) directory server for user authentication and authorization.

When LDAP authentication is enabled, TCM uses a connected LDAP directory server to authenticates users who submit the login form. TCM constructs requests to the servers according to configuration parameters described on this page. Permissions of LDAP users in TCM are defined by LDAP group mapping.

Both LDAP and secure LDAPS (LDAP over TLS) protocols are supported.

Enabling LDAP authentication

To allow LDAP user authentication in TCM, enable the ldap authentication method in the security.auth configuration option before startup:

Примечание

If both authentication methods – LDAP and local – are enabled, TCM tries them for each login attempt in the order they are specified in the configuration.

LDAP configuration

To enable LDAP user access to TCM, create an LDAP configuration that connects TCM to the LDAP server that stores the users. An LDAP configuration defines how TCM connects to the server and queries user data. To create an LDAP configuration, go to the LDAP page in the Settings group and click Add.

To edit an LDAP configuration, click Edit in the Actions menu of the corresponding row.

To delete an LDAP configuration, click Delete in the Actions menu of the corresponding row.

General settings

Define the general configuration settings:

  • Enabled. Defines if the configuration is used. Turn the toggle off to stop using the configuration.

    Примечание

    If there are several enabled LDAP configurations, TCM attempts to use them for user authentication in the order they are created.

  • Automatically add non-existent users. By default, TCM automatically saves LDAP user information to its backend store upon their first login. Turn the toggle off if you don’t want to save users from this LDAP server.

LDAP server connection

Enter the LDAP server connection parameters:

  • Endpoints. URLs of the LDAP server. Example: 127.0.0.1:5056.
  • Request timeout. The timeout for TCM requests to the LDAP server, in seconds.
  • Enabled TLS. If the server uses LDAPS, turn this toggle on and specify TLS connection parameters, such as a certificate and a key file.

LDAP queries

To define how TCM queries the LDAP server for user authentication and authorization, fill in the fields of the Queries step:

  • Query user and Query password. Credentials of the LDAP user on behalf of which all LDAP queries are executed: a distinguished name (DN) and a password. Example DN:

    cn=admin,cn=users,dc=tarantool,dc=io

  • Base DN. The DN of a directory that serves as a root for making all LDAP requests. Example: dc=tarantool,dc=io.

  • Username regex. A regular expression that defines a username template for this LDAP configuration. When a user enters their username on the login page, TCM matches it against username regular expressions of all enabled LDAP configurations and selects the one to use for this user authentication.

    Example: a regex to match employee email addresses within the specified domain.

    ^([\w\-\.]+)@tarantool.io$

  • (Optional) Template DN. A template for building a DN to send in an authentication bind request. Use the numbers in curly braces as placeholders to replace with username regex parts: {0}, {1}, and so on.

    Example:

    cn={0},cn=users,dc=tarantool,dc=io

    When used with the Username regex shown above, it substitutes {0} with the username part of the email address (before @) entered into the login form. For example, the username user1@tarantool.io forms the following DN for bind request:

    cn=user1,cn=users,dc=tarantool,dc=io

  • (Optional) Template query. A template for querying the LDAP server for the DN. This way is used if Template DN is not provided.

  • Group query template. A template for querying groups to which a user belongs for authorization purposes. Learn more in LDAP user permissions. Example:

    (&(objectCategory=person)(objectClass=user)(cn={0}))

LDAP user permissions

Permissions of LDAP users in TCM are defined by the groups to which they belong. You can map TCM administrative and cluster permissions to LDAP groups on the Groups step of the configuration creation.

To assign permissions to an LDAP group, click Add group. In the dialog that opens, enter the group name, for example, CN=Admins,CN=Builtin,DC=tarantool,DC=io. Then, select administrative permission to grant to this group in the Permissions list.

To grant cluster permissions, click Add cluster. Select a cluster and the cluster permissions to grant to the group. Save the group.

Each user has permissions of all LDAP groups to which they belong.

Disabling LDAP configurations

To stop using an LDAP configuration, open its Edit page and turn off the Enabled toggle.

Access control list

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

Tarantool Cluster Manager access control list (ACL) determines user access to particular data and functions stored in clusters. You can use it to allow or deny access to specific stored objects one by one.

Each ACL entry specifies privileges that a TCM user has on a particular space or a function. There are three access privileges that can be granted in the ACL: read, write, and execute (for stored functions only). The privileges work as follows:

Важно

User access to space data and stored functions is primarily defined by the cluster permissions cluster.space.data.* and cluster.func.*. ACL only increases the access control granularity to particular objects. Make sure that users have these permissions before enabling ACL for them.

Enabling ACL for a user

To granularly manage a user’s access to particular objects in a cluster, enable the use of ACL in the user profile:

  1. Go to Users and click Edit in the Actions menu of the corresponding table row.
  2. In the user’s Clusters list, add a cluster on which you want to use ACL or click the pencil icon if the cluster is already on the list.
  3. Select the Use Access Control List (ACL) checkbox and save changes.
  4. Repeat two previous steps for each cluster on which you want to use ACL for this user.
  5. Click Update to save the user account.

If the user doesn’t exist yet, you can do the same when creating it.

Важно

When ACL use is enabled for a user, this user loses access to all spaces and functions of the selected cluster except the ones explicitly specified in the ACL.

Managing ACL

The tools for managing ACL are located on the ACL page.

To add an ACL entry:

  1. Click Add.
  2. Select a user to which you want to grant access.
  3. Select a cluster that stores the target object: a space or a function.
  4. Select the target object type and enter its name.
  5. Select the privileges you want to grant.

To delete an ACL entry, click Delete in the Actions menu of the corresponding table row.

API tokens

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

Tarantool Cluster Manager uses the Bearer HTTP authentication scheme with API tokens to authenticate external applications“ requests to TCM. For example, these can be Prometheus jobs that retrieve metrics of connected Tarantool clusters.

The API tokens functionality is disabled by default. To enable it, set the feature.api-token configuration option to true.

feature:
  api-token: true

Each TCM API token belongs to the user that created it and has the same access permissions. Thus, if a user has a permission to view a cluster’s metrics in TCM, this user’s API tokens can be used to read this cluster’s metrics with Prometheus.

API tokens have expiration dates that are set during the token creation and cannot be changed.

Managing API tokens

Примечание

Each user, including Default Admin and other administrators, can create only their own tokens. There is no way to create a token for another user.

To create a TCM API token:

  1. Open the user settings by clicking the user’s name in the top-right corner.
  2. Go to the API tokens tab and click Add.
  3. Specify the token expiration date and an optional description and click Add.

The created token is shown in a dialog.

Важно

An API token is shown only once after its creation. There is no way to view it again after you close the dialog. Make sure to copy the token in a safe place.

To delete an API token, click Delete in the actions menu of the corresponding API tokens table row.

Administrators can also view information about users“ API tokens and delete them on the Secrets page. To open a user’s secrets, click Secrets in the Actions menu of the corresponding Users table row.

Sessions

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

Tarantool Cluster Manager administrators can view and revoke user sessions in the web interface. All active sessions are listed on the Sessions page. To revoke a session, click Revoke in the Actions menu of the corresponding table row.

To revoke all sessions of a TCM user, go to Users and click Revoke all sessions in the Actions menu of the corresponding table row.

Audit log

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

Tarantool Cluster Manager provides the audit logging functionality for tracking user activity and security-related events, such as:

The complete list of TCM audit events is provided in Event types.

Примечание

TCM audit log records only events that happen in TCM itself. For information about Tarantool audit logging, see Audit module.

Audit logging is disabled in TCM by default. To start recording events, you need to enable and configure it.

The audit log stores event details in the JSON format. Each log entry contains the event type, description, time, impacted objects, and other information that may be used for incident investigation. The complete list of fields is provided in Structure of audit log events.

TCM also provides a built-in interface for reading and searching the audit log. For details, see Viewing audit log.

Enabling audit logging

To enable audit logging in TCM, go to Audit settings and click Enable.

To additionally send audit log events to the standard output, click Send to stdout.

Audit log configuration

TCM audit events can be logged to a local file or sent to a syslog server. To configure audit logging, go to Audit settings.

Writing to a file

To write TCM audit logs to a file:

  1. Go to Audit settings and select the file protocol.
  2. Specify the name of the audit log file. The file appears in the TCM working directory.
  3. Configure the log files rotation: the maximum file size and age, and the number of files to store simultaneously.
  4. (Optional) Enable compression of audit log files.

Configuration parameters:

  • Output file name. The name of the audit log file. Default: audit.log
  • Max size (in MB). The maximum size of the log file before it gets rotated, in megabytes. Default: 100.
  • Max backups. The maximum number of stored audit log files. Default: 10.
  • Max age (in days). The maximum age of audit log files in days. Default: 30.
  • Compress. Compress audit log files into gzip archives when rotating.

Sending to syslog

If you use a centralized log management system based on syslog, you can configure TCM to send its audit log to your syslog server:

  1. Go to Audit settings and select the syslog protocol.
  2. Enter the syslog server URI and select the network protocol. Typically, syslogd listens on port 514 and uses the UDP protocol.
  3. Specify the syslog logging parameters: timeout, priority, and facility.

Configuration parameters:

  • Protocol. The network protocol used for connecting to the syslog server. Default: udp.
  • Output. The syslog server URI. Default: 127.0.0.1:514 (localhost).
  • Timeout. The syslog write timeout in the ISO 8601 duration format. Default: PT2S (two seconds).
  • Priority. The syslog severity level. Default: info.
  • Facility. The syslog facility. Default: local0.

Selecting audit events to record

When the audit log is enabled, TCM records all audit events listed in Event types. To decrease load and make the audit log comply with specific security requirements, you can record only selected events. For example, these can be events of user account management or events of cluster data access.

To select events to record into the audit log, go to Audit settings and enter their types into the Filters field one-by-one, pressing the Enter key after each type.

To remove an event type from a filters list, click the cross icon beside it.

Viewing audit log

If the audit log is written to a file, you can view it in TCM on the Audit log page. On this page, you can view or search for events.

To view the details of a logged audit event, click the corresponding line in the table.

To search for an event, use the search bar at the top of the page. Note that the search is case-sensitive. For example, to find events with the ALARM severity, enter ALARM, not alarm.

Structure of audit log events

All entries of the TCM audit log include the mandatory fields listed in the table below.

Field Description Example
time Time of the event 2023-11-23T12:05:27.099+07:00
severity Event severity: VERBOSE, INFO, WARNING, or ALARM INFO
type Audit event type user.update
description Human-readable event description Update user
uuid Event UUID f8744f51-5760-40c3-ae2d-0b4d6b44836f
user UUID of the user who triggered the event 942a4f54-cf7f-4f46-80ce-3511dbbb57b7
remote Remote host that triggered the event 100.96.163.226:48722
host The TCM host on which the event happened 100.96.163.226:8080
userAgent Information about the client application and platform that was used to trigger the event Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36
permission The permission that was used to trigger the event [«admin.users.write»]
result Event result: ok or nok ok
err Human-readable error description for events with nok result failed to login
fields Additional fields for specific event types in the key-value format

Key examples:

  • clusterId in cluster-related events
  • payload in events that include sending data to the server
  • username in current.* or auth.* events

This is an example of an audit log entry on a successful login attempt:

{
    "time": "2023-11-23T12:01:27.247+07:00",
    "severity": "INFO",
    "description": "Login user",
    "type": "current.login",
    "uuid": "4b9c2dd1-d9a1-4b40-a448-6bef4a0e5c79",
    "user": "",
    "remote": "127.0.0.1:63370",
    "user-agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36",
    "host": "127.0.0.1:8080",
    "permissions": [],
    "result": "ok",
    "fields": [
        {
            "Key": "username",
            "Value": "admin"
        },
        {
            "Key": "method",
            "Value": "null"
        },
        {
            "Key": "output",
            "Value": "true"
        }
    ]
}

Event types

The following table lists all possible values of the type field of TCM audit log events.

Event type Description
auth.fail Authentication failed
auth.ok Authentication successful
access.denied An attempt to access an object without the required permission
user.add User added
user.update User updated
user.delete User deleted
secret.add User secret added
secret.update User secret updated
secret.block User secret blocked
secret.unblock User secret unblocked
secret.delete User secret deleted
secret.expire User secret expired
session.revoke Session revoked
session.revokeuser All user’s sessions revoked
explorer.insert Data inserted in a cluster
explorer.delete Data deleted from a cluster
explorer.replace Data replaced in a cluster
explorer.call Stored function called on a cluster
explorer.evaluate Code executed on a cluster
explorer.switchover Master switched manually
test.devmode Switched to development mode
auditlog.config Audit log configuration changed
passwordpolicy.save Password policy changed
passwordpolicy.resetpasswords All passwords expired by an administrator
ddl.save Cluster data model saved
ddl.apply Cluster data model applied
cluster.config.save Cluster configuration saved
cluster.config.reset Saved cluster configuration reset
cluster.config.apply Cluster configuration applied
current.logout User logged out their own session
current.revoke User revoked their own session
current.revokeall User revoked all their active sessions
current.changepassword User changed their password
role.add Role added
role.update Role updated
role.delete Role deleted
cluster.add Cluster added
cluster.update Cluster updated
cluster.delete Cluster removed
ldap.testlogin Login test executed for a LDAP configuration
ldap.testconnection Connection test executed for a LDAP configuration
ldap.add LDAP configuration added
ldap.update LDAP configuration updated
ldap.delete LDAP configuration deleted
addon.enable Add-on enabled
addon.disable Add-on disabled
addon.delete Add-on removed
tcmstate.save Low-level information saved in the TCM storage (for debug purposes)
tcmstate.delete Low-level information deleted from the TCM storage (for debug purposes)

Configuration

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

This topic describes how to configure Tarantool Cluster Manager. For the complete list of TCM configuration parameters, see the TCM configuration reference.

Примечание

To learn about Tarantool cluster configuration, see Configuration.

Configuration structure

Tarantool Cluster Manager configuration is a set of parameters that define various aspects of TCM functioning. Parameters are grouped by the particular aspect that they affect. There are the following groups:

Parameter groups can be nested. For example, in the http group there are tls and websession-cookie groups, which define TLS encryption and cookie settings.

Parameter names are the full paths from the top-level group to the specific parameter. For example:

Ways to pass configuration parameters

There are three ways to pass TCM configuration parameters:

YAML file

TCM configuration can be stored in a YAML file. Its structure must reflect the configuration parameters hierarchy.

The example below shows a fragment of a TCM configuration file:

# a fragment of a YAML configuration file
cluster: # top-level group
    on-air-limit: 4096
    connection-rate-limit: 512
    tarantool-timeout: 10s
    tarantool-ping-timeout: 5s
http: # top-level group
    basic-auth: # nested group
        enabled: false
    network: tcp
    host: 127.0.0.1
    port: 8080
    request-size: 1572864
    websocket: # nested group
        read-buffer-size: 16384
        write-buffer-size: 16384
        keepalive-ping-interval: 20s
        handshake-timeout: 10s
        init-timeout: 15s

To start TCM with a YAML configuration, pass the location of the configuration file in the -c command-line option:

$ tcm -c=config.yml

Environment variables

TCM can take values of its configuration parameters from environment variables. The variable names start with TCM_. Then goes the full path to the parameter, converted to upper case. All delimiters are replaced with underscores (_). Examples:

  • TCM_HTTP_HOST is a variable for the http.host parameter.
  • TCM_HTTP_WEBSESSION_COOKIE_NAME is a variable for the http.websession-cookie.name parameter.

The example below shows how to start TCM with configuration parameters passed in environment variables:

$ export TCM_HTTP_HOST=0.0.0.0
$ export TCM_HTTP_PORT=8888
$ tcm

Command-line arguments

The TCM executable has -- command-line options for each configuration parameter. Their names reflect the full path to the parameter, with configuration levels separated by periods (.). Examples:

  • --http.host is an option for http.host.
  • --http.websession-cookie.name is an option for http.websession-cookie.name.

The example below shows how to start TCM with configuration parameters passed in command-line options:

$ tcm --storage.etcd.embed.enabled --addon.enabled --http.host=0.0.0.0 --http.port=8888

Configuration precedence

TCM configuration options are applied from multiple sources with the following precedence, from highest to lowest:

  1. tcm executable arguments.
  2. TCM_* environment variables.
  3. Configuration from a YAML file.

If the same option is defined in two or more locations, the option with the highest precedence is applied. For options that aren’t defined in any location, the default values are used.

You can combine different ways of TCM configuration for efficient management of multiple TCM installations:

  • A single YAML file for all installations can contain the common configuration parts. For example, a single configuration storage that is used for all installations, or TLS settings.
  • Environment variables that set specific parameters for each server, such as local directories and paths.
  • Command-line options for parameters that must be unique for different TCM instances running on a single server. For example, http.port.

Configuration parameter types

TCM configuration parameters have the Go language types. Note that this is different from the Tarantool configuration parameters, which have Lua types.

Most options have the Go’s basic types: int and other numeric types, bool, string.

http:
    basic-auth:
        enabled: false # bool
    network: tcp # string
    host: 127.0.0.1 # string
    port: 8080 # int
    request-size: 1572864 # int64

Parameters that can take multiple values are arrays. In YAML, they are passed as YAML arrays: each item on a new line, starting with a dash.

storage:
provider: etcd
etcd:
    endpoints: # array
        - https://192.168.0.1:2379 # item 1
        - https://192.168.0.2:2379 # item 2

Примечание

In environment variables and command line options, such arrays are passed as semicolon-separated strings of items.

Parameters that set timeouts, TTLs, and other duration values, have the Go’s time.Duration type. Their values can be passed in time-formatted strings such as 4h30m25s.

cluster:
    tarantool-timeout: 10s # duration
    tarantool-ping-timeout: 5s # duration

Finally, there are parameters whose values are constants defined in Go packages. For example, http.websession-cookie.same-site values are constants from the Go’s http.SameSite type. To find out the exact values available for such parameters, refer to the Go packages documentation.

http:
    websession-cookie:
        same-site: SameSiteStrictMode

Creating a configuration template

You can create a YAML configuration template for TCM with all parameters and their default values using the generate-config option of the tcm executable.

To write a default TCM configuration to the tcm.example.yml file, run:

$ tcm generate-config > tcm.example.yml.

Backend store

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

Tarantool Cluster Manager uses an underlying data store (backend store) for its entities: users, roles, cluster connections, settings, and other objects that you manipulate in TCM. The backend store can be either an etcd or a Tarantool cluster.

For better reliability and scalability, the backend store works independently from TCM. For example, it can be the same ectd or Tarantool cluster that you use as a centralized configuration storage. This makes TCM stateless: all objects created or modified in its web UI are saved to the backend store, and nothing is stored inside the TCM instances themselves. Any number of instances can duplicate each other when connected to the same backend store. If you stop all instances, the store still contains their objects. You can continue working with them right after starting a new instance.

In addition to using an external backend store, you can run TCM with an embedded etcd or Tarantool instance to use as the backend store.

On this page, you will learn to connect TCM to backend stores of both types, or start TCM with an embedded backend store.

Setting up a backend store

The TCM backend store requires the same configuration as Tarantool centralized configuration storage. Follow the instructions in Setting up a configuration storage to set up a backend store.

Примечание

If you already have the centralized configuration store for your Tarantool clusters, you can use it as a TCM backend store as well.

Configuring backend store connection

The TCM’s connection to its backend store is configured using the storage.* configuration options. The storage.provider option selects the store type. It can be either etcd or tarantool.

External etcd store

To use an etcd cluster as a TCM backend store, set the storage.provider option to etcd and specify connection parameters in storage.etcd.* options. A minimal etcd configuration includes the storage endpoints:

storage:
  provider: etcd
  etcd:
    endpoints:
      - http://127.0.0.1:2379

If authentication is enabled in etcd, specify storage.etcd.username and storage.etcd.password:

storage:
  provider: etcd
  etcd:
    endpoints:
      - http://127.0.0.1:2379
    username: etcduser
    password: secret

The TCM data is stored in etcd under the prefix specified in storage.etcd.prefix. By default, the prefix is /tcm. If you want to change it or store data of different TCM instances separately in one etcd cluster, set the prefix explicitly:

storage:
  provider: etcd
  etcd:
    endpoints:
      - http://127.0.0.1:2379
    prefix: /tcm2

Other storage.etcd.* options configure various aspects of the etcd store connection, such as network timeouts and limits or TLS parameters. For the full list of the etcd TCM backend store options, see the TCM configuration reference.

External Tarantool-based store

To use a Tarantool cluster as a TCM backend store, set the storage.provider option to tarantool and specify connection parameters in storage.tarantool.* options. A minimal configuration includes the one or more addresses of the backend store instances:

storage:
  provider: tarantool
  tarantool:
    addr: http://127.0.0.1:3301

Or:

storage:
  provider: tarantool
  tarantool:
    addrs:
      - http://127.0.0.1:3301
      - http://127.0.0.1:3302
      - http://127.0.0.1:3303

If authentication is enabled in the backend store, specify storage.tarantool.username and storage.tarantool.password:

storage:
  provider: tarantool
  tarantool:
    addr: http://127.0.0.1:3301
    username: tarantooluser
    password: secret

The TCM data is stored in the Tarantool-based backend store under the prefix specified in storage.tarantool.prefix. By default, the prefix is /tcm. If you want to change it or store data of different TCM instances separately in one Tarantool cluster, set the prefix explicitly:

storage:
  provider: tarantool
  tarantool:
    addr: http://127.0.0.1:3301
    username: tarantooluser
    password: secret
    prefix: /tcm2

Other storage.tarantool.* options configure various aspects of TCM connection to the Tarantool-based backend store, such as network timeouts and limits or TLS parameters. For the full list of the Tarantool-based TCM backend store options, see the TCM configuration reference.

Embedded backend store

For development purposes, you can start TCM with an embedded backend store. This is useful for local runs when you don’t have or don’t need an external backend store.

An embedded TCM backend store is a single instance of etcd or Tarantool that is started automatically on the same host during the TCM startup. It runs in the background until TCM is stopped. The embedded backend store is persistent: if you start TCM again with the same backend store configuration, it restores the TCM data from the previous runs.

Примечание

To start a clean instance of TCM, remove the working directory of the embedded backend store specified in the storage.etcd.embed.workdir or storage.tarantool.embed.workdir option.

The embedded backend store parameters are configured using the storage.etcd.embed.* options for etcd or storage.tarantool.embed.* options for a Tarantool-based store.

To start TCM with an embedded etcd with default settings, set storage.etcd.embed.enabled to true and leave other storage.* options default:

storage.etcd.embed.enabled: true

You can use the following call to get TCM running with embedded etcd without a configuration file:

$ tcm --storage.etcd.embed.enabled

To start TCM with an embedded Tarantool storage with default settings:

storage:
  provider: tarantool
  tarantool.embed.enabled: true

With command-line arguments:

$ tcm --storage.provider=tarantool --storage.tarantool.embed.enabled

You can tune the embedded backend store, for example, enable and configure TLS on it or change its working directories or startup arguments. To set specific parameters, specify the corresponding storage.etcd.embed.* or storage.tarantool.embed.* options. For the full list of configuration options of embedded backend stores, see the TCM configuration reference.

Setting up a cluster of embedded backend stores

To simulate the production environment, you can form a distributed multi-instance cluster from embedded stores of multiple TCM instances. To do this, configure each TCM instance’s embedded store to join each other.

For etcd, provide the embedded store clustering parameters storage.etcd.embed.* and specify the endpoints in storage.etcd.endpoints. The options that configure embedded etcd mostly match the etcd configuration options. For more information about these options, see the etcd documentation.

Below are example configurations of three TCM instances that start with embedded etcd instances and form an etcd cluster from them:

  • First instance:

    http.port: 8080
storage:
  provider: etcd
  etcd:
    endpoints:
      - http://127.0.0.1:2379
      - http://127.0.0.1:22379
      - http://127.0.0.1:32379
    embed:
      enabled: true
      name: infra1
      endpoints: http://127.0.0.1:2379
      advertises: http://127.0.0.1:2379
      initial-cluster-state: new
      initial-cluster: infra1=http://127.0.0.1:12380,infra2=http://127.0.0.1:22380,infra3=http://127.0.0.1:32380
      initial-cluster-token: etcd-cluster-1
      peer-endpoints: http://127.0.0.1:12380
      peer-advertises: http://127.0.0.1:12380
      workdir: node1.etcd

  • Second instance:

    http.port: 8081
storage:
  provider: etcd
  etcd:
    endpoints:
      - http://127.0.0.1:2379
      - http://127.0.0.1:22379
      - http://127.0.0.1:32379
    embed:
      enabled: true
      name: infra2
      endpoints: http://127.0.0.1:22379
      advertises: http://127.0.0.1:22379
      initial-cluster-state: new
      initial-cluster: infra1=http://127.0.0.1:12380,infra2=http://127.0.0.1:22380,infra3=http://127.0.0.1:32380
      initial-cluster-token: etcd-cluster-1
      peer-endpoints: http://127.0.0.1:22380
      peer-advertises: http://127.0.0.1:22380
      workdir: node2.etcd

  • Third instance:

    http.port: 8082
storage:
  provider: etcd
  etcd:
    endpoints:
      - http://127.0.0.1:2379
      - http://127.0.0.1:22379
      - http://127.0.0.1:32379
    embed:
      enabled: true
      name: infra3
      endpoints: http://127.0.0.1:32379
      advertises: http://127.0.0.1:32379
      initial-cluster-state: new
      initial-cluster: infra1=http://127.0.0.1:12380,infra2=http://127.0.0.1:22380,infra3=http://127.0.0.1:32380
      initial-cluster-token: etcd-cluster-1
      peer-endpoints: http://127.0.0.1:32380
      peer-advertises: http://127.0.0.1:32380
      workdir: node3.etcd

To set up a cluster from embedded Tarantool-based backend stores:

  1. Specify the Tarantool cluster configuration in storage.tarantool.embed.config (as a plain text) or storage.tarantool.embed.config-file (as a YAML file).
  2. Assign an instance name from this configuration to each instance using storage.tarantool.embed.args to each embedded store.

Below are example configurations of three TCM instances that start with embedded Tarantool-based backend stores and form a cluster from them:

  • First instance:

    http.port: 8080
storage:
  provider: tarantool
  tarantool:
    addrs:
      - http://127.0.0.1:3301
      - http://127.0.0.1:3302
      - http://127.0.0.1:3303
    embed:
      enabled: true
      config-filename: config.yml
      workdir: node1.tarantool
      args:
        - --name
        - instance-001
        - --config
        - config.yml

  • Second instance:

    http.port: 8081
storage:
  provider: tarantool
  tarantool:
    addrs:
      - http://127.0.0.1:3301
      - http://127.0.0.1:3302
      - http://127.0.0.1:3303
    embed:
      enabled: true
      config-filename: config.yml
      workdir: node2.tarantool
      args:
        - --name
        - instance-002
        - --config
        - config.yml

  • Third instance:

    http.port: 8082
storage:
  provider: tarantool
  tarantool:
    addrs:
      - http://127.0.0.1:3301
      - http://127.0.0.1:3302
      - http://127.0.0.1:3303
    embed:
      enabled: true
      config-filename: config.yml
      workdir: node3.tarantool
      args:
        - --name
        - instance-003
        - --config
        - config.yml

Configuration reference

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

This topic describes configuration parameters of Tarantool Cluster Manager.

There are the following groups of TCM configuration parameters:

cluster

The cluster group defines parameters of TCM interaction with connected Tarantool clusters.

cluster.connection-rate-limit

A rate limit for connections to Tarantool instances.


Type: uint
Default: 512
Environment variable: TCM_CLUSTER_CONNECTION_RATE_LIMIT
Command-line option: --cluster.connection-rate-limit
cluster.tarantool-timeout

A timeout for receiving a response from Tarantool instances.


Type: time.Duration
Default: 10s
Environment variable: TCM_CLUSTER_TARANTOOL_TIMEOUT
Command-line option: --cluster.tarantool-timeout
cluster.tarantool-ping-timeout

A timeout for receiving a ping response from Tarantool instances.


Type: time.Duration
Default: 5s
Environment variable: TCM_CLUSTER_TARANTOOL_PING_TIMEOUT
Command-line option: --cluster.tarantool-ping-timeout
cluster.tt-command

The command that runs the tt utility on hosts with cluster instances.


Type: string
Default: tt
Environment variable: TCM_CLUSTER_TT_COMMAND
Command-line option: --cluster.tt-command
cluster.refresh-state-period

The time interval for refreshing the cluster instances state on the Stateboard.


Type: time.Duration
Default: 5s
Environment variable: TCM_CLUSTER_REFRESH_STATE_PERIOD
Command-line option: --cluster.refresh-state-period
cluster.refresh-state-timeout

The time limit for refreshing an instance state. If this limit is reached, an error is shown.


Type: time.Duration
Default: 4s
Environment variable: TCM_CLUSTER_REFRESH_STATE_TIMEOUT
Command-line option: --cluster.refresh-state-timeout
cluster.discovery-period

The time interval for checking the leadership in replica sets.


Type: time.Duration
Default: 4s
Environment variable: TCM_CLUSTER_DISCOVERY_PERIOD
Command-line option: --cluster.discovery-period
cluster.sharding-index

The name of the space field that is used as a sharding key.


Type: String
Default: bucket_id
Environment variable: TCM_CLUSTER_SHARDING_INDEX
Command-line option: --cluster.sharding-index
cluster.skew-time

The maximum time skew between any two cluster instances. If this limit is reached, a warning is shown.


Type: time.Duration
Default: 30s
Environment variable: TCM_CLUSTER_SKEW_TIME
Command-line option: --cluster.skew-time
cluster.fragmentation-threshold

The count of allocated slabs that reflects high memory fragmentation. When this number is reached, a warning is shown.

See also: Хранение данных с помощью memtx


Type: int
Default: 40
Environment variable: TCM_CLUSTER_FRAGMENTATION_THRESHOLD
Command-line option: --cluster.fragmentation-threshold

http

The http group defines parameters of HTTP connections between TCM and clients.

http.network

An addressing scheme that TCM uses.

Possible values:

  • tcp: IPv4 address
  • tcp6: IPv6 address
  • unix: Unix domain socket

Type: string
Default: tcp
Environment variable: TCM_HTTP_NETWORK
Command-line option: --http.network
http.host

A host name on which TCM serves.


Type: string
Default: 127.0.0.1
Environment variable: TCM_HTTP_HOST
Command-line option: --http.host
http.port

A port on which TCM serves.


Type: int
Default: 8080
Environment variable: TCM_HTTP_PORT
Command-line option: --http.port
http.request-size

The maximum size (in bytes) of a client HTTP request to TCM.


Type: int64
Default: 1572864
Environment variable: TCM_HTTP_REQUEST_SIZE
Command-line option: --http.request-size
http.websocket.read-buffer-size

The size (in bytes) of the read buffer for WebSocket connections.


Type: int
Default: 16384
Environment variable: TCM_HTTP_WEBSOCKET_READ_BUFFER_SIZE
Command-line option: --http.websocket.read-buffer-size
http.websocket.write-buffer-size

The size (in bytes) of the write buffer for WebSocket connections.


Type: int
Default: 16384
Environment variable: TCM_HTTP_WEBSOCKET_WRITE_BUFFER_SIZE
Command-line option: --http.websocket.write-buffer-size
http.websocket.keepalive-ping-interval

The time interval for sending WebSocket keepalive pings.


Type: time.Duration
Default: 20s
Environment variable: TCM_HTTP_WEBSOCKET_KEEPALIVE_PING_INTERVAL
Command-line option: --http.websocket.keepalive-ping-interval
http.websocket.handshake-timeout

The time limit for completing a WebSocket opening handshake with a client.


Type: time.Duration
Default: 10s
Environment variable: TCM_HTTP_WEBSOCKET_HANDSHAKE_TIMEOUT
Command-line option: --http.websocket.handshake-timeout
http.websocket.init-timeout

The time limit for establishing a WebSocket connection with a client.


Type: time.Duration
Default: 15s
Environment variable: TCM_HTTP_WEBSOCKET_INIT_TIMEOUT
Command-line option: --http.websocket.init-timeout
http.websession-cookie.name

The name of the cookie that TCM sends to clients.

This value is used as the cookie name in the Set-Cookie HTTP response header.


Type: string
Default: tcm
Environment variable: TCM_HTTP_WEBSESSION_COOKIE_NAME
Command-line option: ---http.websession-cookie.name
http.websession-cookie.path

The URL path that must be present in the requested URL in order to send the cookie.

This value is used in the Path attribute of the Set-Cookie HTTP response header.


Type: string
Default: «»
Environment variable: TCM_HTTP_WEBSESSION_COOKIE_PATH
Command-line option: ---http.websession-cookie.path
http.websession-cookie.domain

The domain to which the cookie can be sent.

This value is used in the Domain attribute of the Set-Cookie HTTP response header.


Type: string
Default: «»
Environment variable: TCM_HTTP_WEBSESSION_COOKIE_DOMAIN
Command-line option: ---http.websession-cookie.domain
http.websession-cookie.ttl

The maximum lifetime of the TCM cookie.

This value is used in the Max-Age attribute of the Set-Cookie HTTP response header.


Type: time.Duration
Default: 2h0m0s
Environment variable: TCM_HTTP_WEBSESSION_COOKIE_TTL
Command-line option: ---http.websession-cookie.ttl
http.websession-cookie.secure

Indicates whether the cookie can be sent only over the HTTPS protocol. In this case, it’s never sent over the unencrypted HTTP, therefore preventing man-in-the-middle attacks.

When true, the Secure attribute is added to the Set-Cookie HTTP response header.


Type: bool
Default: false
Environment variable: TCM_HTTP_WEBSESSION_COOKIE_SECURE
Command-line option: ---http.websession-cookie.secure
http.websession-cookie.http-only

Indicates that the cookie can’t be accessed from the JavaScript Document.cookie API. This helps mitigate cross-site scripting attacks.

When true, the HttpOnly attribute is added to the Set-Cookie HTTP response header.


Type: bool
Default: true
Environment variable: TCM_HTTP_WEBSESSION_COOKIE_HTTP_ONLY
Command-line option: ---http.websession-cookie.http-only
http.websession-cookie.same-site

Indicates if it is possible to send the TCM cookie along with cross-site requests. Possible values are the Go’s http.SameSite constants:

  • SameSiteDefaultMode
  • SameSiteLaxMode
  • SameSiteStrictMode
  • SameSiteNoneMode

For details on SameSite modes, see the Set-Cookie header documentation in the MDN web docs.

This value is used in the SameSite attribute of the Set-Cookie HTTP response header.


Type: http.SameSite
Default: SameSiteDefaultMode
Environment variable: TCM_HTTP_WEBSESSION_COOKIE_SAME_SITE
Command-line option: ---http.websession-cookie.same-site
http.cors.enabled

Indicates whether to use the Cross-Origin Resource Sharing (CORS).


Type: bool
Default: false
Environment variable: TCM_HTTP_CORS_ENABLED
Command-line option: --http.cors.enabled
http.cors.allowed-origins

The origins with which the HTTP response can be shared, separated by semicolons.

The specified values are sent in the Access-Control-Allow-Origin HTTP response headers.


Type: []string
Default: []
Environment variable: TCM_HTTP_CORS_ALLOWED_ORIGINS
Command-line option: --http.cors.allowed-origins
http.cors.allowed-methods

HTTP request methods that are allowed when accessing a resource, separated by semicolons.

The specified values are sent in the Access-Control-Allow-Methods HTTP header of a response to a CORS preflight request.


Type: []string
Default: []
Environment variable: TCM_HTTP_CORS_ALLOWED_METHODS
Command-line option: --http.cors.allowed-methods
http.cors.allowed-headers

HTTP headers that are allowed during the actual request, separated by semicolons.

The specified values are sent in the Access-Control-Allow-Headers HTTP header of a response to a CORS preflight request.


Type: []string
Default: []
Environment variable: TCM_HTTP_CORS_ALLOWED_HEADERS
Command-line option: --http.cors.allowed-headers
http.cors.exposed-headers

Response headers that should be made available to scripts running in the browser, in response to a cross-origin request, separated by semicolons.

The specified values are sent in the Access-Control-Expose-Headers HTTP response headers.


Type: []string
Default: []
Environment variable: TCM_HTTP_CORS_EXPOSED_HEADERS
Command-line option: --http.cors.exposed-headers
http.cors.allow-credentials

Whether to expose the response to the frontend JavaScript code when the request’s credentials mode is include.

When true, the Access-Control-Allow-Credentials HTTP response header is sent.


Type: bool
Default: false
Environment variable: TCM_HTTP_CORS_ALLOW_CREDENTIALS
Command-line option: --http.cors.allow-credentials
http.cors.debug

For debug purposes.


Type: bool
Default: false
http.tls.enabled

Indicates whether TLS is enabled for client connections to TCM.


Type: bool
Default: false
Environment variable: TCM_HTTP_TLS_ENABLED
Command-line option: --http.tls.enabled
http.tls.cert-file

A path to a TLS certificate file. Mandatory when TLS is enabled.


Type: string
Default: «»
Environment variable: TCM_HTTP_TLS_CERT_FILE
Command-line option: --http.tls.cert-file
http.tls.key-file

A path to a TLS private key file. Mandatory when TLS is enabled.


Type: string
Default: «»
Environment variable: TCM_HTTP_TLS_KEY_FILE
Command-line option: --http.tls.key-file
http.tls.server

The TLS server.


Type: string
Default: «»
Environment variable: TCM_HTTP_TLS_SERVER
Command-line option: --http.tls.server
http.tls.min-version

The minimum version of the TLS protocol.


Type: uint16
Default: 0
Environment variable: TCM_HTTP_TLS_MIN_VERSION
Command-line option: --http.tls.min-version
http.tls.max-version

The maximum version of the TLS protocol.


Type: uint16
Default: 0
Environment variable: TCM_HTTP_TLS_MAX_VERSION
Command-line option: --http.tls.max-version
http.tls.curve-preferences

Elliptic curves that are used for TLS connections. Possible values are the Go’s tls.CurveID constants:

  • CurveP256
  • CurveP384
  • CurveP521
  • X25519

Type: []tls.CurveID
Default: []
Environment variable: TCM_HTTP_TLS_CURVE_PREFERENCES
Command-line option: --http.tls.curve-preferences
http.tls.cipher-suites

Enabled TLS cipher suites. Possible values are the Golang tls.TLS_* constants.


Type: []uint16
Default: []
Environment variable: TCM_HTTP_TLS_CIPHER_SUITES
Command-line option: --http.tls.cipher-suites
http.read-timeout

A timeout for reading an incoming request.


Type: time.Duration
Default: 30s
Environment variable: TCM_HTTP_READ_TIMEOUT
Command-line option: --http.read-timeout
http.read-header-timeout

A timeout for reading headers of an incoming request.


Type: time.Duration
Default: 30s
Environment variable: TCM_HTTP_READ_HEADER_TIMEOUT
Command-line option: --http.read-header-timeout
http.write-timeout

A timeout for writing a response.


Type: time.Duration
Default: 30s
Environment variable: TCM_HTTP_WRITE_TIMEOUT
Command-line option: --http.write-timeout
http.idle-timeout

The timeout for idle connections.


Type: time.Duration
Default: 30s
Environment variable: TCM_HTTP_IDLE_TIMEOUT
Command-line option: --http.idle-timeout
http.disable-general-options-handler

Whether the client requests with the OPTIONS HTTP method are allowed.


Type: bool
Default: false
Environment variable: TCM_HTTP_DISABLE_GENERAL_OPTIONS_HANDLER
Command-line option: --http.disable-general-options-handler
http.max-header-bytes

The maximum size (in bytes) of a header in a client’s request to TCM.


Type: int
Default: 0
Environment variable: TCM_HTTP_MAX_HEADER_BYTES
Command-line option: --http.max-header-bytes
http.api-timeout

The stateboard update timeout.


Type: time.Duration
Default: 8s
Environment variable: TCM_HTTP_API_TIMEOUT
Command-line option: --http.api-timeout
http.api-update-interval

The stateboard update interval.


Type: time.Duration
Default: 5s
Environment variable: TCM_HTTP_API_UPDATE_INTERVAL
Command-line option: --http.api-update-interval
http.frontend-dir

The directory with custom TCM frontend files (for development purposes).


Type: string
Default: «»
Environment variable: TCM_HTTP_FRONTEND_DIR
Command-line option: --http.frontend-dir
http.show-stack-trace

Whether error stack traces are shown in the web UI.


Type: bool
Default: true
Environment variable: TCM_HTTP_SHOW_STACK_TRACE
Command-line option: --http.show-stack-trace
http.trace

Whether all query tracing information is written in logs.


Type: bool
Default: false
Environment variable: TCM_HTTP_TRACE
Command-line option: --http.trace
http.max-static-size

The maximum size (in bytes) of a static content sent to TCM.


Type: int
Default: 104857600
Environment variable: TCM_HTTP_MAX_STATIC_SIZE
Command-line option: --http.max-static-size
http.graphql.complexity

The maximum complexity of GraphQL queries that TCM processes. If this value is exceeded, TCM returns an error.


Type: int
Default: 40
Environment variable: TCM_HTTP_GRAPHQL_COMPLEXITY
Command-line option: --http.graphql.complexity

log

The log section defines the TCM logging parameters.

log.default.add-source

Whether sources are added to the TCM log.


Type: bool
Default: false
Environment variable: TCM_LOG_DEFAULT_ADD_SOURCE
Command-line option: --log.default.add-source
log.default.show-stack-trace

Whether stack traces are added to the TCM log.


Type: bool
Default: false
Environment variable: TCM_LOG_DEFAULT_SHOW_STACK_TRACE
Command-line option: --log.default.show-stack-trace
log.default.level

The default TCM logging level.

Possible values:

  • VERBOSE
  • INFO
  • WARN
  • ALARM

Type: string
Default: INFO
Environment variable: TCM_LOG_DEFAULT_LEVEL
Command-line option: --log.default.level
log.default.format

TCM log entries format.

Possible values:

  • struct
  • json

Type: string
Default: struct
Environment variable: TCM_LOG_DEFAULT_FORMAT
Command-line option: --log.default.format
log.default.output

The output used for TCM log.

Possible values:

  • stdout
  • stderr
  • file
  • syslog

Type: string
Default: stdout
Environment variable: TCM_LOG_DEFAULT_OUTPUT
Command-line option: --log.default.output
log.default.no-colorized

Whether the stdout log is not colorized.


Type: bool
Default: false
Environment variable: TCM_LOG_DEFAULT_NO_COLORIZED
Command-line option: --log.default.no-colorized
log.default.file.name

The name of the TCM log file.


Type: string
Default: «»
Environment variable: TCM_LOG_DEFAULT_FILE_NAME
Command-line option: --log.default.file.name
log.default.file.maxsize

The maximum size (in bytes) of the TCM log file.


Type: int
Default: 0
Environment variable: TCM_LOG_DEFAULT_FILE_MAXSIZE
Command-line option: --log.default.file.maxsize
log.default.file.maxage

The maximum age of a TCM log file, in days.


Type: int
Default: 0
Environment variable: TCM_LOG_DEFAULT_FILE_MAXAGE
Command-line option: --log.default.file.maxage
log.default.file.maxbackups

The maximum number of users in TCM.


Type: int
Default: 0
Environment variable: TCM_LOG_DEFAULT_FILE_MAXBACKUPS
Command-line option: --log.default.file.maxbackups
log.default.file.compress

Indicated that TCM compresses log files upon rotation.


Type: bool
Default: false
Environment variable: TCM_LOG_DEFAULT_FILE_COMPRESS
Command-line option: --log.default.file.compress
log.default.syslog.protocol

The network protocol used for connecting to the syslog server. Typically, it’s tcp, udp, or unix. All possible values are listed in the Go’s net.Dial documentation.


Type: string
Default: tcp
Environment variable: TCM_LOG_DEFAULT_SYSLOG_PROTOCOL
Command-line option: --log.default.syslog.protocol
log.default.syslog.output

The syslog server URI.


Type: string
Default: 127.0.0.1:5514
Environment variable: TCM_LOG_DEFAULT_SYSLOG_OUTPUT
Command-line option: --log.default.syslog.output
log.default.syslog.priority

The syslog severity level.


Type: string
Default: «»
Environment variable: TCM_LOG_DEFAULT_SYSLOG_PRIORITY
Command-line option: --log.default.syslog.priority
log.default.syslog.facility

The syslog facility.


Type: string
Default: «»
Environment variable: TCM_LOG_DEFAULT_SYSLOG_FACILITY
Command-line option: --log.default.syslog.facility
log.default.syslog.tag

The syslog tag.


Type: string
Default: «»
Environment variable: TCM_LOG_DEFAULT_SYSLOG_TAG
Command-line option: --log.default.syslog.tag
log.default.syslog.timeout

The timeout for connecting to the syslog server.


Type: time.Duration
Default: 10s
Environment variable: TCM_LOG_DEFAULT_SYSLOG_TIMEOUT
Command-line option: --log.default.syslog.timeout
log.outputs

An array of log outputs that TCM uses in addition to the default one that is defined by the log.default.* parameters. Each array item can include the parameters of the log.default group. If a parameter is skipped, its value is taken from log.default.


Type: []LogOuputConfig
Default: []
Environment variable: TCM_LOG_OUTPUTS
Command-line option: --log-outputs

storage

The storage section defines the parameters of the TCM data storage.

etcd storage parameters:

Tarantool storage parameters:

storage.provider

The type of the storage used for storing TCM configuration.

Possible values:

  • etcd
  • tarantool

Type: string
Default: etcd
Environment variable: TCM_STORAGE_PROVIDER
Command-line option: --storage.provider
storage.etcd.prefix

A prefix for the TCM configuration parameters in etcd.


Type: string
Default: «/tcm»
Environment variable: TCM_STORAGE_ETCD_PREFIX
Command-line option: --storage.etcd.prefix
storage.etcd.endpoints

An array of node URIs of the etcd cluster where the TCM configuration is stored, separated by semicolons (;).


Type: []string
Default: [«http://127.0.0.1:2379»]
Environment variable: TCM_STORAGE_ETCD_ENDPOINTS
Command-line option: --storage.etcd.endpoints
storage.etcd.dial-timeout

An etcd dial timeout.


Type: time.Duration
Default: 10s
Environment variable: TCM_STORAGE_ETCD_DIAL_TIMEOUT
Command-line option: --storage.etcd.dial-timeout
storage.etcd.auto-sync-interval

An automated sync interval.


Type: time.Duration
Default: 0s
Environment variable: TCM_STORAGE_ETCD_AUTO_SYNC_INTERVAL
Command-line option: --storage.etcd.auto-sync-interval
storage.etcd.dial-keep-alive-time

A dial keep-alive time.


Type: time.Duration
Default: 30s
Environment variable: TCM_STORAGE_ETCD_DIAL_KEEP_ALIVE_TIME
Command-line option: --storage.etcd.dial-keep-alive-time
storage.etcd.dial-keep-alive-timeout

A dial keep-alive timeout.


Type: time.Duration
Default: 30s
Environment variable: TCM_STORAGE_ETCD_DIAL_KEEP_ALIVE_TIMEOUT
Command-line option: --storage.etcd.dial-keep-alive-timeout
storage.etcd.bootstrap-timeout

A bootstrap timeout.


Type: time.Duration
Default: 30s
Environment variable: TCM_STORAGE_ETCD_BOOTSTRAP_TIMEOUT
Command-line option: --storage.etcd.bootstrap-timeout
storage.etcd.max-call-send-msg-size

The maximum size (in bytes) of a transaction between TCM and etcd.


Type: int
Default: 2097152
Environment variable: TCM_STORAGE_ETCD_MAX_CALL_SEND_MSG_SIZE
Command-line option: --storage.etcd.max-call-send-msg-size
storage.etcd.username

A username for accessing the etcd storage.


Type: string
Default: «»
Environment variable: TCM_STORAGE_ETCD_USERNAME
Command-line option: --storage.etcd.username
storage.etcd.password

A password for accessing the etcd storage.


Type: string
Default: «»
Environment variable: TCM_STORAGE_ETCD_PASSWORD
Command-line option: --storage.etcd.password
storage.etcd.password-file

A path to the file with a password for accessing the etcd storage.


Type: string
Default: «»
Environment variable: TCM_STORAGE_ETCD_PASSWORD_FILE
Command-line option: --storage.etcd.password-file
storage.etcd.tls.enabled

Indicates whether TLS is enabled for etcd connections.


Type: bool
Default: false
Environment variable: TCM_STORAGE_ETCD_TLS_ENABLED
Command-line option: --storage.etcd.tls.enabled
storage.etcd.tls.auto

Use generated certificates for etcd connections.


Type: bool
Default: false
Environment variable: TCM_STORAGE_ETCD_TLS_AUTO
Command-line option: --storage.etcd.tls.auto
storage.etcd.tls.cert-file

A path to a TLS certificate file to use for etcd connections.


Type: string
Default: «»
Environment variable: TCM_STORAGE_ETCD_TLS_CERT_FILE
Command-line option: --storage.etcd.tls.cert-file
storage.etcd.tls.key-file

A path to a TLS private key file to use for etcd connections.


Type: string
Default: «»
Environment variable: TCM_STORAGE_ETCD_TLS_KEY_FILE
Command-line option: --storage.etcd.tls.key-file
storage.etcd.tls.trusted-ca-file

A path to a trusted CA certificate file to use for etcd connections.


Type: string
Default: «»
Environment variable: TCM_STORAGE_ETCD_TLS_TRUSTED_CA_FILE
Command-line option: --storage.etcd.tls.trusted-ca-file
storage.etcd.tls.client-cert-auth

Indicates whether client cert authentication is enabled.


Type: bool
Default: false
Environment variable: TCM_STORAGE_ETCD_TLS_CLIENT_CERT_AUTH
Command-line option: --storage.etcd.tls.client-cert-auth
storage.etcd.tls.crl-file

A path to the client certificate revocation list file.


Type: string
Default: «»
Environment variable: TCM_STORAGE_ETCD_TLS_CRL_FILE
Command-line option: --storage.etcd.tls.crl-file
storage.etcd.tls.insecure-skip-verify

Skip checking client certificate in etcd connections.


Type: bool
Default: false
Environment variable: TCM_STORAGE_ETCD_TLS_INSECURE_SKIP_VERIFY
Command-line option: --storage.etcd.tls.insecure-skip-verify
storage.etcd.tls.skip-client-san-verify

Skip verification of SAN field in client certificate for etcd connections.


Type: bool
Default: false
Environment variable: TCM_STORAGE_ETCD_TLS_SKIP_CLIENT_SAN_VERIFY
Command-line option: --storage.etcd.tls.skip-client-san-verify
storage.etcd.tls.server-name

Name of the TLS server for etcd connections.


Type: string
Default: «»
Environment variable: TCM_STORAGE_ETCD_TLS_SERVER_NAME
Command-line option: --storage.etcd.tls.server-name
storage.etcd.tls.cipher-suites

TLS cipher suites for etcd connections. Possible values are the Golang tls.TLS_* constants.


Type: []uint16
Default: []
Environment variable: TCM_STORAGE_ETCD_TLS_CIPHER_SUITES
Command-line option: --storage.etcd.tls.cipher-suites
storage.etcd.tls.allowed-cn

An allowed common name for authentication in etcd connections.


Type: string
Default: «»
Environment variable: TCM_STORAGE_ETCD_TLS_ALLOWED_CN
Command-line option: --storage.etcd.tls.allowed-cn
storage.etcd.tls.allowed-hostname

An allowed TLS certificate name for authentication in etcd connections.


Type: string
Default: «»
Environment variable: TCM_STORAGE_ETCD_TLS_ALLOWED_HOSTNAME
Command-line option: --storage.etcd.tls.allowed-hostname
storage.etcd.tls.empty-cn

Whether the empty common name is allowed in etcd connections.


Type: bool
Default: false
Environment variable: TCM_STORAGE_ETCD_TLS_EMPTY_CN
Command-line option: --storage.etcd.tls.empty-cn
storage.etcd.permit-without-stream

Whether keepalive pings can be send to the etcd server without active streams.


Type: bool
Default: false
Environment variable: TCM_STORAGE_ETCD_PERMIT_WITHOUT_STREAM
Command-line option: --storage.etcd.permit-without-stream

storage.etcd.embed.*

The storage.etcd.embed group defines the configuration of the embedded etcd cluster that can used as a TCM configuration storage. This cluster can be used for development purposes when the production or testing etcd cluster is not available or not needed.

storage.tarantool.prefix

A prefix for the TCM configuration parameters in the Tarantool-based configuration storage.


Type: string
Default: «/tcm»
Environment variable: TCM_STORAGE_TARANTOOL_PREFIX
Command-line option: --storage.tarantool.prefix
storage.tarantool.addr

The URI for connecting to the Tarantool-based configuration storage.


Type: string
Default: «unix/:/tmp/tnt_config_instance.sock»
Environment variable: TCM_STORAGE_TARANTOOL_ADDR
Command-line option: --storage.tarantool.addr
storage.tarantool.addrs

An array of the Tarantool-based configuration storage URIs.


Type: []string
Default: [«unix/:/tmp/tnt_config_instance.sock»]
Environment variable: TCM_STORAGE_TARANTOOL_ADDRS
Command-line option: --storage.tarantool.addrs
storage.tarantool.auth

An authentication method for the Tarantool-based configuration storage.

Possible values are the Go’s go-tarantool/Auth constants:

  • AutoAuth (0)
  • ChapSha1Auth
  • PapSha256Auth

Type: int
Default: 0
Environment variable: TCM_STORAGE_TARANTOOL_AUTH
Command-line option: --storage.tarantool.auth
storage.tarantool.timeout

A request timeout for the Tarantool-based configuration storage.

See also go-tarantool.Opts.


Type: time.Duration
Default: 0s
Environment variable: TCM_STORAGE_TARANTOOL_TIMEOUT
Command-line option: --storage.tarantool.timeout
storage.tarantool.reconnect

A timeout between reconnect attempts for the Tarantool-based configuration storage.

See also go-tarantool.Opts.


Type: time.Duration
Default: 0s
Environment variable: TCM_STORAGE_TARANTOOL_RECONNECT
Command-line option: --storage.tarantool.reconnect
storage.tarantool.max-reconnects

The maximum number of reconnect attempts for the Tarantool-based configuration storage.

See also go-tarantool.Opts.


Type: int
Default: 0
Environment variable: TCM_STORAGE_TARANTOOL_MAX_RECONNECTS
Command-line option: --storage.tarantool.max-reconnects
storage.tarantool.username

A username for connecting to the Tarantool-based configuration storage.

See also go-tarantool.Opts.


Type: string
Default: «»
Environment variable: TCM_STORAGE_TARANTOOL_USERNAME
Command-line option: --storage.tarantool.username
storage.tarantool.password

A password for connecting to the Tarantool-based configuration storage.

See also go-tarantool.Opts.


Type: string
Default: «»
Environment variable: TCM_STORAGE_TARANTOOL_PASSWORD
Command-line option: --storage.tarantool.password
storage.tarantool.password-file

A path to the file with a password for connecting to the Tarantool-based configuration storage.


Type: string
Default: «»
Environment variable: TCM_STORAGE_TARANTOOL_PASSWORD_FILE
Command-line option: --storage.tarantool.password-file
storage.tarantool.rate-limit

A rate limit for connecting to the Tarantool-based configuration storage.

See also go-tarantool.Opts.


Type: int
Default: 0
Environment variable: TCM_STORAGE_TARANTOOL_RATE_LIMIT
Command-line option: --storage.tarantool.rate-limit
storage.tarantool.rate-limit-action

An action to perform when the storage.tarantool.rate-limit is reached.

See also go-tarantool.Opts.


Type: int
Default: 0
Environment variable: TCM_STORAGE_TARANTOOL_RATE_LIMIT_ACTION
Command-line option: --storage.tarantool.rate-limit-action
storage.tarantool.concurrency

An amount of separate mutexes for request queues and buffers inside of a connection to the Tarantool TCM configuration storage.

See also go-tarantool.Opts.


Type: int
Default: 0
Environment variable: TCM_STORAGE_TARANTOOL_CONCURRENCY
Command-line option: --storage.tarantool.concurrency
storage.tarantool.skip-schema

Whether the schema is loaded from the Tarantool TCM configuration storage.

See also go-tarantool.Opts.


Type: bool
Default: true
Environment variable: TCM_STORAGE_TARANTOOL_SKIP_SCHEMA
Command-line option: --storage.tarantool.skip-schema
storage.tarantool.transport

The connection type for the Tarantool TCM configuration storage.

See also go-tarantool.Opts.


Type: string
Default: «»
Environment variable: TCM_STORAGE_TARANTOOL_TRANSPORT
Command-line option: --storage.tarantool.transport
storage.tarantool.ssl.key-file

A path to a TLS private key file to use for connecting to the Tarantool TCM configuration storage.

See also: Securing connections with SSL.


Type: string
Default: «»
Environment variable: TCM_STORAGE_TARANTOOL_SSL_KEY_FILE
Command-line option: --storage.tarantool.ssl.key-file
storage.tarantool.ssl.cert-file

A path to an SSL certificate to use for connecting to the Tarantool TCM configuration storage.

See also: Securing connections with SSL.


Type: string
Default: «»
Environment variable: TCM_STORAGE_TARANTOOL_SSL_CERT_FILE
Command-line option: --storage.tarantool.ssl.cert-file
storage.tarantool.ssl.ca-file

A path to a trusted CA certificate to use for connecting to the Tarantool TCM configuration storage.

See also: Securing connections with SSL.


Type: string
Default: «»
Environment variable: TCM_STORAGE_TARANTOOL_SSL_CA_FILE
Command-line option: --storage.tarantool.ssl.ca-file
storage.tarantool.ssl.ciphers

A list of SSL cipher suites that can be used for connecting to the Tarantool TCM configuration storage. Possible values are listed in <uri>.params.ssl_ciphers.

See also: Securing connections with SSL.


Type: string
Default: «»
Environment variable: TCM_STORAGE_TARANTOOL_SSL_CIPHERS
Command-line option: --storage.tarantool.ssl.ciphers
storage.tarantool.ssl.password

A password for an encrypted private SSL key to use for connecting to the Tarantool TCM configuration storage.

See also: Securing connections with SSL.


Type: string
Default: «»
Environment variable: TCM_STORAGE_TARANTOOL_SSL_PASSWORD
Command-line option: --storage.tarantool.ssl.password
storage.tarantool.ssl.password-file

A text file with passwords for encrypted private SSL keys to use for connecting to the Tarantool TCM configuration storage.

See also: Securing connections with SSL.


Type: string
Default: «»
Environment variable: TCM_STORAGE_TARANTOOL_SSL_PASSWORD_FILE
Command-line option: --storage.tarantool.ssl.password-file
storage.tarantool.required-protocol-info.auth

An authentication method for the Tarantool TCM configuration storage.

Possible values are the Go’s go-tarantool/Auth constants:

  • AutoAuth (0)
  • ChapSha1Auth
  • PapSha256Auth

See also go-tarantool.ProtocolInfo.


Type: int
Default: 0
Environment variable: TCM_STORAGE_TARANTOOL_SSL_REQUIRED_PROTOCOL_INFO_AUTH
Command-line option: --storage.tarantool.required-protocol-info.auth
storage.tarantool.required-protocol-info.version

A Tarantool protocol version.

See also go-tarantool.ProtocolInfo.


Type: uint64
Default: 0
Environment variable: TCM_STORAGE_TARANTOOL_SSL_REQUIRED_PROTOCOL_INFO_VERSION
Command-line option: --storage.tarantool.required-protocol-info.version
storage.tarantool.required-protocol-info.features

An array of Tarantool protocol features.

See also go-tarantool.ProtocolInfo.


Type: []int
Default: []
Environment variable: TCM_STORAGE_TARANTOOL_SSL_REQUIRED_PROTOCOL_INFO_FEATURES
Command-line option: --storage.tarantool.required-protocol-info.features

storage.tarantool.embed.*

The storage.tarantool.embed group parameters define the configuration of the embedded Tarantool cluster that can used as a TCM configuration storage. This cluster can be used for development purposes when the production or testing cluster is not available or not needed.

addon

The addon section defines settings related to TCM add-ons.

addon.enabled

Whether to enable the add-on functionality in TCM.


Type: bool
Default: false
Environment variable: TCM_ADDON_ENABLED
Command-line option: --addon.enabled
addon.addons-dir

The directory from which TCM takes add-ons.


Type: string
Default: addons
Environment variable: TCM_ADDON_ADDONS_DIR
Command-line option: --addon.addons-dir
addon.max-upload-size

The maximum size (in bytes) of addon to upload to TCM.


Type: int64
Default: 104857600
Environment variable: TCM_ADDON_MAX_UPLOAD_SIZE
Command-line option: --addon.max-upload-size
addon.dev-addons-dir

Additional add-on directories for development purposes, separated by semicolons (;).


Type: []string
Default: []
Environment variable: TCM_ADDON_DEV_ADDONS_DIR
Command-line option: --addon.dev-addons-dir

limits

The limits section defines limits on various TCM objects and relations between them.

limits.users-count

The maximum number of users in TCM.


Type: int
Default: 1000
Environment variable: TCM_LIMITS_USERS_COUNT
Command-line option: --limits.users-count
limits.clusters-count

The maximum number of clusters in TCM.


Type: int
Default: 10
Environment variable: TCM_LIMITS_CLUSTERS_COUNT
Command-line option: --limits.clusters-count
limits.roles-count

The maximum number of roles in TCM.


Type: int
Default: 100
Environment variable: TCM_LIMITS_ROLES_COUNT
Command-line option: --limits.roles-count
limits.webhooks-count

The maximum number of webhooks in TCM.


Type: int
Default: 200
Environment variable: TCM_LIMITS_WEBHOOKS_COUNT
Command-line option: --limits.webhooks-count
limits.user-secrets-count

The maximum number secrets that a TCM user can have.


Type: int
Default: 10
Environment variable: TCM_LIMITS_USER_SECRETS_COUNT
Command-line option: --limits.user-secrets-count
limits.user-websessions-count

The maximum number of open sessions that a TCM user can have.


Type: int
Default: 10
Environment variable: TCM_LIMITS_USER_WEBSESSIONS_COUNT
Command-line option: --limits.user-websessions-count
limits.linked-cluster-users

The maximum number of clusters to which a single user can have access.


Type: int
Default: 10
Environment variable: TCM_LIMITS_LINKED_CLUSTER_USERS
Command-line option: --limits.linked-cluster-users

security

The security section defines the security parameters of TCM.

security.auth

Ways to log into TCM.

Possible values:

  • local
  • ldap

Type: []string
Default: [local]
Environment variable: TCM_SECURITY_AUTH
Command-line option: --security.auth
security.hash-cost

A hash cost for hashing users“ passwords.


Type: int
Default: 12
Environment variable: TCM_SECURITY_HASH_COST
Command-line option: --security.hash-cost
security.encryption-key

An encryption key for passwords used by TCM for accessing Tarantool and etcd clusters.


Type: string
Default: «»
Environment variable: TCM_SECURITY_ENCRYPTION_KEY
Command-line option: --security.encryption-key
security.encryption-key-file

A path to the file with the encryption key for passwords used by TCM for accessing Tarantool and etcd clusters.


Type: string
Default: «»
Environment variable: TCM_SECURITY_ENCRYPTION_KEY_FILE
Command-line option: --security.encryption-key-file
security.bootstrap-password

A password for the first login of the admin user. Only for testing purposes.


Type: string
Default: «»
Environment variable: TCM_SECURITY_BOOTSTRAP_PASSWORD
Command-line option: --security.bootstrap-password
security.bootstrap-api-token

A default API token for the admin user. Only for testing purposes.


Type: string
Default: «»
Environment variable: TCM_SECURITY_BOOTSTRAP_API_TOKEN
Command-line option: --security.bootstrap-api-token
security.integrity-check

Whether to check the digital signature. If true, the error is raised in case an incorrect signature is detected.


Type: bool
Default: false
Environment variable: TCM_SECURITY_INTEGRITY_CHECK
Command-line option: --security.integrity-check
security.signature-private-key-file

A path to a file with the private key to sign TCM data.


Type: string
Default: «»
Environment variable: TCM_SECURITY_SIGNATURE_PRIVATE_KEY_FILE
Command-line option: --security.signature-private-key-file

mode

mode

The TCM mode: production, development, or test.


Type: string
Default: production
Environment variable: TCM_MODE
Command-line option: --mode

feature

The feature section defines the security parameters of TCM.

feature.ttgraph

Whether Tarantool Graph DB integration is enabled.


Type: bool
Default: false
Environment variable: TCM_FEATURE_TTGRAPH
Command-line option: --feature.ttgraph
feature.column-store

Whether Tarantool Column Store integration is enabled.


Type: bool
Default: false
Environment variable: TCM_FEATURE_COLUMN_STORE
Command-line option: --feature.column-store
feature.tqe

Whether Tarantool Queue Enterprise integration is enabled.


Type: bool
Default: false
Environment variable: TCM_FEATURE_TQE
Command-line option: --feature.tqe
feature.api-token

Whether the use of API tokens is enabled.


Type: bool
Default: false
Environment variable: TCM_FEATURE_API_TOKEN
Command-line option: --feature.api-token

Tarantool Cluster Manager releases

Enterprise Edition

Tarantool Cluster Manager is a part of the Enterprise Edition.

This section contains the list of Tarantool Cluster Manager releases along with descriptions of their key changes.

For information about Tarantool releases, see Примечания к версиям.

Supported versions

Series First release date Versions
1.2 July 30, 2024
1.2.1
1.2.0
1.1 May 16, 2024 1.1.0
1.0 December 23, 2023
1.0.4
1.0.3
1.0.2
1.0.1
1.0.0

Tarantool Cluster Manager 1.2

Release date: July 30, 2024

Latest release in series: 1.2.1

Tarantool Cluster Manager 1.2 introduces new features that extend its cluster management capabilities. Below is an overview of its key updates.

Managing Tarantool users

TCM 1.2 introduces the ability to manage Tarantool users on connected clusters. Previously, you could manage Tarantool users only though the Lua API (box.schema submodule) or cluster configuration. Now you can create, edit, and delete users and roles on each instance of a Tarantool cluster through the TCM web interface.

The tools for managing Tarantool users on a cluster instance are located on the Users tab of the instance page.

Learn more about managing Tarantool users from TCM in Managing cluster users and roles.

Migrations

Since version 1.2.0, TCM includes a page for editing and executing migrations on connected clusters. The new page Migrations in the Cluster page group provides a text editor where you can write migration scripts in Lua and apply them to the cluster.

Learn more about migrations in Tarantool Migrations.

Cluster security settings

Since version 1.2.2, TCM provides a web interface for managing cluster security settings on the Security page in the Cluster group.

Learn more about managing cluster security from TCM in Security settings.

TCF integration

Since version 1.2.2, TCM includes a page for managing clusters that run within Tarantool Clusters Federation.

Learn more about working with TCF in TCM in TCF integration.

Tarantool Cluster Manager 1.1

Release date: May 16, 2024

Latest release in series: 1.1.0

Tarantool Cluster Manager 1.1 introduces a number of new features that extend and improve its cluster management capabilities. Below is an overview of its key updates.

Data access

An important update of TCM 1.1.0 is a set of features that enable access to clusters“ stored data.

The instance space explorer shows all spaces that exist on an instance, including system spaces. On its pages, you can view and edit the stored data. To open the instance explorer, find the instance on the cluster stateboard and click its name to open its details page. Then click Explorer in the Actions menu in the top right corner.

In the development mode, the instance explorer also includes the schema editor. It allows you to add new and edit existing spaces.

For clusters that use the CRUD module, there is also the CRUD explorer that enables access to data in user spaces across the entire cluster. The CRUD explorer is located on the Tuples page.

Access control list

TCM’s access control list (ACL) enables control over user access to particular spaces and stored functions in the web interface.

For each user that has access to a cluster, you can enable the use of ACL on this cluster. This restricts this user’s access to the cluster’s spaces and functions unless they are explicitly specified in the ACL. The ACL must contain an entry for each such space and function.

Users with ACL off have access to all spaces and functions on clusters according to their cluster permissions.

The tools for managing ACL are located on the new ACL page.

API tokens

TCM 1.1 supports token authentication of external requests. Users can generate API tokens in their user settings dialog. An API token has the same permissions as its creator.

Stateboard improvements

TCM 1.1 extends the functionality of the cluster stateboard to improve the cluster management experience. Here are the key updates of the stateboard:

Instance interaction

The instance management dialog has been extended with new functions:

Cluster metrics

Starting from version 1.1.0, TCM displays metrics of connected clusters. You can view metrics in TCM one by one, visualizing them as charts or tables. The cluster metrics are shown on the new Cluster metrics page.

For more complex monitoring, you can use dedicated solutions, for example, Prometheus. It can integrate with TCM using the API tokens.

Configuration validation

The cluster configuration editor now validates the configuration semantically. Previously, TCM was able to highlight the syntax errors in configurations, for example, incorrect spelling of option names or hierarchy. In TCM 1.1.0, the editor checks and highlights possible semantic issues, such as:

Onboarding tutorial

TCM 1.1.0 includes an interactive tutorial that takes new users through its main features and pages. It opens automatically after the first start.

Tarantool Cluster Manager 1.0

Release date: December 26, 2023

Latest release in series: 1.0.4

1.0 is the first public release series of Tarantool Cluster Manager. It was introduced as a part of the Tarantool EE 3.0 release. Below is an overview of key features of TCM 1.0.

Multiple connected clusters

TCM works as a standalone application. You can connect any number of Tarantool EE 3.0+ clusters to a single TCM instance and switch between them on the fly.

To connect a cluster to TCM, you need to provide the endpoint URLs and connection parameters of its centralized configuration storage (for example, etcd). To learn more, see Connecting clusters.

Cluster stateboard

The cluster stateboard is a main TCM page that visualizes the information about the selected cluster:

From the stateboard, you can navigate to specific instances to view their details or connect to their interactive consoles.

To learn more, see Viewing cluster state.

Cluster configuration management

TCM includes a visual editor for cluster configuration. It allows editing cluster configurations as a YAML file in the browser. Once you’re done editing the configuration, you can send the changes to the configuration storage in one click or save them locally to continue editing them later.

To learn more, see Configuring clusters.

Role-based access control

TCM features its own role-based access control system. It defines users that can log into TCM and their permissions to perform various actions or access clusters in its web interface.

You can use built-in roles or create new ones with permissions you need. Users“ access can be limited to specific clusters and operations on them, for example, editing the configuration or calling stored functions. To learn more, see Access control.

TCM also supports LDAP authentication.

Audit logging

TCM has a built-in audit logging mechanism. When enabled, it records information about events that occur in TCM and users“ actions to dedicated audit log files. You can define events to write to the audit log and adjust logging parameters, such as filename, log rotation, or compression.

To learn more, see Audit log.

Interactive console

The interactive console is Tarantool’s basic command-line interface for entering requests and seeing results. It is what users see when they start the server without an instance file. The interactive console is often called the Lua console to distinguish it from the administrative console, but in fact it can handle both Lua and SQL input.

The majority of examples in this manual show what users see with the interactive console. It includes:

-- Interactive console example with Lua input and YAML output --
tarantool> box.info().replication
---
- 1:
    id: 1
    uuid: a5d22f66-2d28-4a35-b78f-5bf73baf6c8a
    lsn: 0
...

Interactive console input and output

The input language can be either Lua (default) or SQL. To change the input language, run \set language <language>, for example:

-- Set input language to SQL --
tarantool> \set language sql
---
- true
...

The delimiter can be changed to any character with \set delimiter <character>. By default, the delimiter is empty, which means the input does not need to end with a delimiter. For example, a common recommendation for SQL input is to use the semicolon delimiter:

-- Set ';' delimiter --
tarantool> \set delimiter ;
---
...

The output format can be either YAML (default) or Lua. To change the output format, run \set output <format>, for example:

-- Set output format Lua --
tarantool> \set output lua
true

The default YAML output format is the following:

The alternative Lua format for console output is the following:

So, when an input is a Lua object description, the output in the Lua format equals it.

For the Lua output format, you can specify an end of statement symbol. It is added to the end of each output statement in the current session and can be used for parsing the output by scripts. By default, the end of statement symbol is empty. You can change it to any character or character sequence. To set an end of statement symbol for the current session, run \`set output lua,local_eos=<symbol>`, for example:

-- Set output format Lua and '#' end of statement symbol --
tarantool> \set output lua,local_eos=#
true#

To switch back to the empty end of statement symbol:

-- Set output format Lua and empty end of statement symbol --
tarantool> \set output lua,local_eos=
true

The YAML output has better readability. The Lua output can be reused in requests. The table below shows output examples in these formats compared with the MsgPack format, which is good for database storage.

Type Lua input Lua output YAML output MsgPack storage
scalar 1 1
---
- 1
...
 \x01
scalar sequence 1, 2, 3 1, 2, 3
---
- 1
- 2
- 3
...
 \x01 \x02 \x03
2-element table {1, 2} {1, 2}
---
- - 1
  - 2
...
 0x92 0x01 0x02
map {key = 1} {key = 1}
---
- key: 1
...
 \x81 \xa3 \x6b \x65 \x79 \x01

The console parameters of a Tarantool instance can also be changed from another instance using the console built-in module functions.

Keyboard shortcuts

Since 2.10.0.

Keyboard shortcut Effect
CTRL+C Discard current input with the SIGINT signal in the console mode and jump to a new line with a default prompt.
CTRL+D Quit Tarantool interactive console.

Важно

Keep in mind that CTRL+C shortcut will shut Tarantool down if there is any currently running command in the console. The SIGINT signal stops the instance running in a daemon mode.

LuaJIT memory profiler

Starting from version 2.7.1, Tarantool has a built‑in module called misc.memprof that implements a LuaJIT memory profiler (which we will just call the profiler in this section). The profiler provides a memory allocation report that helps analyze Lua code and find the places that put the most pressure on the Lua garbage collector (GC).

Working with the profiler

Usage of the profiler involves two steps:

  1. Collecting a binary profile of allocations, reallocations, and deallocations in memory related to Lua (further, binary memory profile or binary profile for short).
  2. Parsing the collected binary profile to get a human-readable profiling report.

Collecting binary profile

To collect a binary profile for a particular part of the Lua code, you need to place this part between two misc.memprof functions, namely, misc.memprof.start() and misc.memprof.stop(), and then execute the code under Tarantool.

Below is a chunk of Lua code named test.lua to illustrate this.

 1-- Prevent allocations on traces.
 2jit.off()
 3local str, err = misc.memprof.start("memprof_new.bin")
 4-- Lua doesn't create a new frame to call string.rep, and all allocations
 5-- are attributed not to the append() function but to the parent scope.
 6local function append(str, rep)
 7    return string.rep(str, rep)
 8end
 9
10local t = {}
11for i = 1, 1e4 do
12    -- table.insert is the built-in function and all corresponding
13    -- allocations are reported in the scope of the main chunk.
14    table.insert(t,
15        append('q', i)
16    )
17end
18local stp, err = misc.memprof.stop()

The Lua code for starting the profiler – as in line 3 in the test.lua example above – is:

local str, err = misc.memprof.start(FILENAME)

where FILENAME is the name of the binary file where profiling events are written.

If the operation fails, for example if it is not possible to open a file for writing or if the profiler is already running, misc.memprof.start() returns nil as the first result, an error-message string as the second result, and a system-dependent error code number as the third result. If the operation succeeds, misc.memprof.start() returns true.

The Lua code for stopping the profiler – as in line 18 in the test.lua example above – is:

local stp, err = misc.memprof.stop()

If the operation fails, for example if there is an error when the file descriptor is being closed or if there is a failure during reporting, misc.memprof.stop() returns nil as the first result, an error-message string as the second result, and a system-dependent error code number as the third result. If the operation succeeds, misc.memprof.stop() returns true.

To generate the file with memory profile in binary format (in the test.lua code example above the file name is memprof_new.bin), execute the code under Tarantool:

$ tarantool test.lua

Tarantool collects the allocation events in memprof_new.bin, puts the file in its working directory, and closes the session.

The test.lua code example above also illustrates the memory allocation logic in some cases that are important to understand for reading and analyzing a profiling report:

  • Line 2: It is recommended to switch the JIT compilation off by calling jit.off() before the profiler start. Refer to the following note about jitoff for more details.
  • Lines 6-8: Tail call optimization doesn’t create a new call frame, so all allocations inside the function called via the CALLT/CALLMT bytecodes are attributed to the function’s caller. See also the comments preceding these lines.
  • Lines 14-16: Usually the information about allocations inside Lua built‑ins is not really useful for developers. That’s why if a Lua built‑in function is called from a Lua function, the profiler attributes all allocations to the Lua function. Otherwise, this event is attributed to a C function. See also the comments preceding these lines.

Parsing binary profile and generating profiling report

After getting the memory profile in binary format, the next step is to parse it to get a human-readable profiling report. You can do this via Tarantool by using the following command (mind the hyphen - before the filename):

$ tarantool -e 'require("memprof")(arg)' - memprof_new.bin

where memprof_new.bin is the binary profile generated earlier by tarantool test.lua. (Warning: there is a slight behavior change here, the tarantool -e ... command was slightly different in Tarantool versions prior to Tarantool 2.8.1.)

Tarantool generates a profiling report and displays it on the console before closing the session:

ALLOCATIONS
@test.lua:14: 10000 events  +50240518 bytes -0 bytes
@test.lua:9: 1 events       +32 bytes       -0 bytes
@test.lua:8: 1 events       +20 bytes       -0 bytes
@test.lua:13: 1 events      +24 bytes       -0 bytes

REALLOCATIONS
@test.lua:13: 13 events     +262216 bytes   -131160 bytes
    Overrides:
        @test.lua:13

@test.lua:14: 11 events     +49536 bytes    -24768 bytes
            Overrides:
        @test.lua:14
        INTERNAL

INTERNAL: 3 events          +8448 bytes     -16896 bytes
    Overrides:
        @test.lua:14

DEALLOCATIONS
INTERNAL: 1723 events       +0 bytes        -483515 bytes
@test.lua:14: 1 events      +0 bytes        -32768 bytes

HEAP SUMMARY:
@test.lua:14 holds 50248326 bytes: 10010 allocs, 10 frees
@test.lua:13 holds 131080 bytes: 14 allocs, 13 frees
INTERNAL holds 8448 bytes: 3 allocs, 3 frees
@test.lua:9 holds 32 bytes: 1 allocs, 0 frees
@test.lua:8 holds 20 bytes: 1 allocs, 0 frees

Примечание

On macOS, a report will be different for the same chunk of code because Tarantool and LuaJIT are built with the GC64 mode enabled for macOS.

Let’s examine the report structure. A report has four sections:

Each section contains event records that are sorted from the most frequent to the least frequent.

An event record has the following format:

@<filename>:<line_number>: <number_of_events> events +<allocated> bytes -<freed> bytes
  • <filename>—a name of the file containing Lua code.
  • <line_number>—the line number where the event is detected.
  • <number_of_events>—a number of events for this code line.
  • +<allocated> bytes—amount of memory allocated during all the events on this line.
  • -<freed> bytes—amount of memory freed during all the events on this line.

The Overrides label shows what allocation has been overridden.

See the test.lua chunk above with the explanation in the comments for some examples.

The INTERNAL label indicates that this event is caused by internal LuaJIT structures.

Примечание

Important note regarding the INTERNAL label and the recommendation of switching the JIT compilation off (jit.off()): this version of the profiler doesn’t support verbose reporting for allocations on traces. If memory allocations are made on a trace, the profiler can’t associate the allocations with the part of Lua code that generated the trace. In this case, the profiler labels such allocations as INTERNAL.

So, if the JIT compilation is on, new traces will be generated and there will be a mixture of events labeled INTERNAL in the profiling report: some of them are really caused by internal LuaJIT structures, but some of them are caused by allocations on traces.

If you want to have a more definite report without JIT compiler allocations, call jit.off() before starting the profiling. And if you want to completely exclude the trace allocations from the report, remove also the old traces by additionally calling jit.flush() after jit.off().

Nevertheless, switching the JIT compilation off before the profiling is not «a must». It is rather a recommendation, and in some cases, for example in a production environment, you may need to keep JIT compilation on to see the full picture of all the memory allocations. In this case, the majority of the INTERNAL events are most probably caused by traces.

As for investigating the Lua code with the help of profiling reports, it is always code-dependent and there can’t be hundred per cent definite recommendations in this regard. Nevertheless, you can see some of the things in the Profiling report analysis example later.

Also, below is the FAQ section with the questions that most probably can arise while using profiler.

FAQ

In this section, some profiler-related points are discussed in a Q&A format.

Question (Q): Is the profiler suitable for C allocations or allocations inside C code?

Answer (A): The profiler reports only allocation events caused by the Lua allocator. All Lua-related allocations, like table or string creation are reported. But the profiler doesn’t report allocations made by malloc() or other non-Lua allocators. You can use valgrind to debug them.


Q: Why are there so many INTERNAL allocations in my profiling report? What does it mean?

A: INTERNAL means that these allocations/reallocations/deallocations are related to the internal LuaJIT structures or are made on traces. Currently, the profiler doesn’t verbosely report allocations of objects that are made during trace execution. Try adding jit.off() before the profiler start.


Q: Why are there some reallocations/deallocations without an Overrides section?

A: These objects can be created before the profiler starts. Adding collectgarbage() before the profiler’s start enables collecting all previously allocated objects that are dead when the profiler starts.


Q: Why are some objects not collected during profiling? Is it a memory leak?

A: LuaJIT uses incremental Garbage Collector (GC). A GC cycle may not be finished at the moment the profiler stops. Add collectgarbage() before stopping the profiler to collect all the dead objects for sure.


Q: Can I profile not just a current chunk but the entire running application? Can I start the profiler when the application is already running?

A: Yes. Here is an example of code that can be inserted in the Tarantool console for a running instance.

 1local fiber = require "fiber"
 2local log = require "log"
 3
 4fiber.create(function()
 5  fiber.name("memprof")
 6
 7  collectgarbage() -- Collect all objects already dead
 8  log.warn("start of profile")
 9
10  local st, err = misc.memprof.start(FILENAME)
11  if not st then
12    log.error("failed to start profiler: %s", err)
13  end
14
15  fiber.sleep(TIME)
16
17  collectgarbage()
18  st, err = misc.memprof.stop()
19
20  if not st then
21    log.error("profiler on stop error: %s", err)
22  end
23
24  log.warn("end of profile")
25end)

where

Also, you can directly call misc.memprof.start() and misc.memprof.stop() from a console.

Profiling report analysis example

In the example below, the following Lua code named format_concat.lua is investigated with the help of the memory profiler reports.

 1-- Prevent allocations on new traces.
 2jit.off()
 3
 4local function concat(a)
 5  local nstr = a.."a"
 6  return nstr
 7end
 8
 9local function format(a)
10  local nstr = string.format("%sa", a)
11  return nstr
12end
13
14collectgarbage()
15
16local binfile = "/tmp/memprof_"..(arg[0]):match("([^/]*).lua")..".bin"
17
18local st, err = misc.memprof.start(binfile)
19assert(st, err)
20
21-- Payload.
22for i = 1, 10000 do
23  local f = format(i)
24  local c = concat(i)
25end
26collectgarbage()
27
28local st, err = misc.memprof.stop()
29assert(st, err)
30
31os.exit()

When you run this code under Tarantool and then parse the binary memory profile in /tmp/memprof_format_concat.bin, you will get the following profiling report:

ALLOCATIONS
@format_concat.lua:10: 19996 events +624284 bytes   -0 bytes
INTERNAL: 1 events                  +65536 bytes    -0 bytes

REALLOCATIONS

DEALLOCATIONS
INTERNAL: 19996 events              +0 bytes        -558778 bytes
    Overrides:
        @format_concat.lua:10

@format_concat.lua:10: 2 events     +0 bytes        -98304 bytes
    Overrides:
        @format_concat.lua:10

HEAP SUMMARY:
INTERNAL holds 65536 bytes: 1 allocs, 0 frees

Reasonable questions regarding the report can be:

First of all, LuaJIT doesn’t create a new string if the string with the same payload exists (see details on lua-users.org/wiki). This is called string interning. So, when a string is created via the format() function, there is no need to create the same string via the concat() function, and LuaJIT just uses the previous one.

That is also the reason why the number of allocations is not a round number as could be expected from the cycle operator for i = 1, 10000...: Tarantool creates some strings for internal needs and built‑in modules, so some strings already exist.

But why are there so many allocations? It’s almost twice as big as the expected amount. This is because the string.format() built‑in function creates another string necessary for the %s identifier, so there are two allocations for each iteration: for tostring(i) and for string.format("%sa", string_i_value). You can see the difference in behavior by adding the line local _ = tostring(i) between lines 22 and 23.

To profile only the concat() function, comment out line 23 (which is local f = format(i)) and run the profiler. Now the output looks like this:

ALLOCATIONS
@format_concat.lua:5: 10000 events  +284411 bytes    -0 bytes

REALLOCATIONS

DEALLOCATIONS
INTERNAL: 10000 events              +0 bytes         -218905 bytes
    Overrides:
        @format_concat.lua:5

@format_concat.lua:5: 1 events      +0 bytes         -32768 bytes

HEAP SUMMARY:
@format_concat.lua:5 holds 65536 bytes: 10000 allocs, 9999 frees

Q: But what will change if JIT compilation is enabled?

A: In the code, comment out line 2 (which is jit.off()) and run the profiler . Now there are only 56 allocations in the report, and all other allocations are JIT-related (see also the related dev issue):

ALLOCATIONS
@format_concat.lua:5: 56 events +1112 bytes -0 bytes
@format_concat.lua:0: 4 events  +640 bytes  -0 bytes
INTERNAL: 2 events              +382 bytes  -0 bytes

REALLOCATIONS

DEALLOCATIONS
INTERNAL: 58 events             +0 bytes    -1164 bytes
    Overrides:
        @format_concat.lua:5
        INTERNAL


HEAP SUMMARY:
@format_concat.lua:0 holds 640 bytes: 4 allocs, 0 frees
INTERNAL holds 360 bytes: 2 allocs, 1 frees

This happens because a trace has been compiled after 56 iterations (the default value of the hotloop compiler parameter). Then, the JIT-compiler removed the unused variable c from the trace, and, therefore, the dead code of the concat() function is eliminated.

Next, let’s profile only the format() function with JIT enabled. For that, comment out lines 2 and 24 (jit.off() and local c = concat(i)), do not comment out line 23 (local f = format(i)), and run the profiler. Now the output will look like this:

ALLOCATIONS
@format_concat.lua:10: 19996 events +624284 bytes  -0 bytes
INTERNAL: 4 events                  +66928 bytes   -0 bytes
@format_concat.lua:0: 4 events      +640 bytes     -0 bytes

REALLOCATIONS

DEALLOCATIONS
INTERNAL: 19997 events              +0 bytes       -559034 bytes
    Overrides:
        @format_concat.lua:0
        @format_concat.lua:10

@format_concat.lua:10: 2 events     +0 bytes       -98304 bytes
    Overrides:
        @format_concat.lua:10


HEAP SUMMARY:
INTERNAL holds 66928 bytes: 4 allocs, 0 frees
@format_concat.lua:0 holds 384 bytes: 4 allocs, 1 frees

Q: Why are there so many allocations in comparison to the concat() function?

A: The answer is simple: the string.format() function with the %s identifier is not yet compiled via LuaJIT. So, a trace can’t be recorded and the compiler doesn’t perform the corresponding optimizations.

If we change the format() function in lines 9-12 of the Profiling report analysis example in the following way

local function format(a)
  local nstr = string.format("%sa", tostring(a))
  return nstr
end

the profiling report becomes much prettier:

ALLOCATIONS
@format_concat.lua:10: 109 events   +2112 bytes -0 bytes
@format_concat.lua:0: 4 events      +640 bytes  -0 bytes
INTERNAL: 3 events                  +1206 bytes -0 bytes

REALLOCATIONS

DEALLOCATIONS
INTERNAL: 112 events                +0 bytes    -2460 bytes
    Overrides:
        @format_concat.lua:0
        @format_concat.lua:10
        INTERNAL


HEAP SUMMARY:
INTERNAL holds 1144 bytes: 3 allocs, 1 frees
@format_concat.lua:0 holds 384 bytes: 4 allocs, 1 frees

The heap summary and the –leak-only option

This feature was added in version 2.8.1.

The end of each display is a HEAP SUMMARY section which looks like this:

@<filename>:<line number> holds <number of still reachable bytes> bytes:
<number of allocation events> allocs, <number of deallocation events> frees

Sometimes a program can cause many deallocations, so the DEALLOCATION section can become large, so the display is not easy to read. To minimize output, start the parsing with an extra flag: --leak-only, for example

$ tarantool -e 'require("memprof")(arg)' - --leak-only memprof_new.bin

When --leak-only` is used, only the HEAP SUMMARY section is displayed.

LuaJIT getmetrics

Tarantool can return metrics of a current instance via the Lua API or the C API.

misc.getmetrics()

getmetrics()

Get the metrics values into a table.

Parameters: none

Return:table

Example: metrics_table = misc.getmetrics()

getmetrics table values

The metrics table contains 19 values. All values have type = „number“ and are the result of a cast to double, so there may be a very slight precision loss. Values whose names begin with gc_ are associated with the LuaJIT garbage collector; a fuller study of the garbage collector can be found at a Lua-users wiki page and a slide from the creator of Lua. Values whose names begin with jit_ are associated with the «phases» of the just-in-time compilation process; a fuller study of JIT phases can be found at A masters thesis from cern.ch.

Values described as «monotonic» are cumulative, that is, they are «totals since all operations began», rather than «since the last getmetrics() call». Overflow is possible.

Because many values are monotonic, a typical analysis involves calling getmetrics(), saving the table, calling getmetrics() again and comparing the table to what was saved. The difference is a «slope curve». An interesting slope curve is one that shows acceleration, for example the difference between the latest value and the previous value keeps increasing. Some of the table members shown here are used in the examples that come later in this section.

Name Content Monotonic?
gc_allocated number of bytes of allocated memory yes
gc_cdatanum number of allocated cdata objects no
gc_freed number of bytes of freed memory yes
gc_steps_atomic number of steps of garbage collector, atomic phases, incremental yes
gc_steps_finalize number of steps of garbage collector, finalize yes
gc_steps_pause number of steps of garbage collector, pauses yes
gc_steps_propagate number of steps of garbage collector, propagate yes
gc_steps_sweep number of steps of garbage collector, sweep phases (see the Sweep phase description) yes
gc_steps_sweepstring number of steps of garbage collector, sweep phases for strings yes
gc_strnum number of allocated string objects no
gc_tabnum number of allocated table objects no
gc_total number of bytes of currently allocated memory (normally equals gc_allocated minus gc_freed) no
gc_udatanum number of allocated udata objects no
jit_mcode_size total size of all allocated machine code areas no
jit_snap_restore overall number of snap restores, based on the number of guard assertions leading to stopping trace executions (see external Snap tutorial) yes
jit_trace_abort overall number of aborted traces yes
jit_trace_num number of JIT traces no
strhash_hit number of strings being interned because, if a string with the same value is found via the hash, a new one is not created / allocated yes
strhash_miss total number of strings allocations during the platform lifetime yes

Note: Although value names are similar to value names in ujit.getmetrics() the values are not the same, primarily because many ujit numbers are not monotonic.

Note: Although value names are similar to value names in LuaJIT metrics, and the values are exactly the same, misc.getmetrics() is slightly easier because there is no need to ‘require’ the misc module.

getmetrics C API

The Lua getmetrics() function is a wrapper for the C function luaM_metrics().

C programs may include a header named libmisclib.h. The definitions in libmisclib.h include the following lines:

struct luam_Metrics { /* the names described earlier for Lua */ }

LUAMISC_API void luaM_metrics(lua_State *L, struct luam_Metrics *metrics);

The names of struct luam_Metrics members are the same as Lua’s getmetrics table values names. The data types of struct luam_Metrics members are all size_t. The luaM_metrics() function will fill the *metrics structure with the metrics related to the Lua state anchored to the L coroutine.

Example with a C program

Go through the C stored procedures tutorial. Replace the easy.c example with

#include "module.h"
#include <lmisclib.h>

int easy(box_function_ctx_t *ctx, const char *args, const char *args_end)
{
  lua_State *ls = luaT_state();
  struct luam_Metrics m;
  luaM_metrics(ls, &m);
  printf("allocated memory = %lu\n", m.gc_allocated);
  return 0;
}

Now when you go back to the client and execute the requests up to and including the line capi_connection:call('easy') you will see that the display is something like «allocated memory = 4431950» although the number will vary.

Example with gc_strnum, strhash_miss, and strhash_hit

To track new string object allocations:

function f()
  collectgarbage("collect")
  local oldm = misc.getmetrics()
  local table_of_strings = {}
  for i = 3000, 4000 do table.insert(table_of_strings, tostring(i)) end
  for i = 3900, 4100 do table.insert(table_of_strings, tostring(i)) end
  local newm = misc.getmetrics()
  print("gc_strnum diff = " .. newm.gc_strnum - oldm.gc_strnum)
  print("strhash_miss diff = " .. newm.strhash_miss - oldm.strhash_miss)
  print("strhash_hit diff = " .. newm.strhash_hit - oldm.strhash_hit)
end
f()

The result will probably be: «gc_strnum diff = 1100» because we added 1202 strings but 101 were duplicates, «strhash_miss_diff = 1100» for the same reason, «strhash_hit_diff = 101» plus some overhead, for the same reason. (There is always a slight overhead amount for strhash_hit, which can be ignored.)

We say «probably» because there is a chance that the strings were already allocated somewhere. It is a good thing if the slope curve of strhash_miss is less than the slope curve of strhash_hit.

The other gc_*num values – gc_cdatanum, gc_tabnum, gc_udatanum – can be accessed in a similar way. Any of the gc_*num values can be useful when looking for memory leaks – the total number of these objects should not grow nonstop. A more general way to look for memory leaks is to watch gc_total. Also jit_mcode_size can be used to watch the amount of allocated memory for machine code traces.

Example with gc_allocated and gc_freed

To track an application’s effect on the garbage collector (less is better):

function f()
  for i = 1, 10 do collectgarbage("collect") end
  local oldm = misc.getmetrics()
  local newm = misc.getmetrics()
  oldm = misc.getmetrics()
  collectgarbage("collect")
  newm = misc.getmetrics()
  print("gc_allocated diff = " .. newm.gc_allocated - oldm.gc_allocated)
  print("gc_freed diff = " .. newm.gc_freed - oldm.gc_freed)
end
f()

The result will be: gc_allocated diff = 800, gc_freed diff = 800. This shows that local ... = getmetrics() itself causes memory allocation (because it is creating a table and assigning to it), and shows that when the name of a variable (in this case the oldm variable) is used again, that causes freeing. Ordinarily the freeing would not occur immediately, but collectgarbage("collect") forces it to happen so we can see the effect.

Example with gc_allocated and a space optimization

To test whether optimizing for space is possible with tables:

function f()
  collectgarbage("collect")
  local oldm = misc.getmetrics()
  local t = {}
  for i = 1, 513 do
    t[i] = i
  end
  local newm = misc.getmetrics()
  local diff = newm.gc_allocated - oldm.gc_allocated
  print("diff = " .. diff)
end
f()

The result will show that diff equals approximately 18000.

Now see what happens if the table initialization is different:

function f()
  local table_new = require "table.new"
  local oldm = misc.getmetrics()
  local t = table_new(513, 0)
  for i = 1, 513 do
    t[i] = i
  end
  local newm = misc.getmetrics()
  local diff = newm.gc_allocated - oldm.gc_allocated
  print("diff = " .. diff)
end
f()

The result will show that diff equals approximately 6000.

gc_steps_atomic and gc_steps_propagate

The slope curves of gc_steps_* items can be used for tracking pressure on the garbage collector too. During long-running routines, gc_steps_* values will increase, but long times between gc_steps_atomic increases are a good sign, And, since gc_steps_atomic increases only once per garbage-collector cycle, it shows how many garbage-collector cycles have occurred.

Also, increases in the gc_steps_propagate number can be used to estimate indirectly how many objects there are. These values also correlate with the garbage collector’s step multiplier. For example, the number of incremental steps can grow, but according to the step multiplier configuration, one step can process only a small number of objects. So these metrics should be considered when configuring the garbage collector.

The following function takes a casual look whether an SQL statement causes much pressure:

function f()
  collectgarbage("collect")
  local oldm = misc.getmetrics()
  collectgarbage("collect")
  box.execute([[DROP TABLE _vindex;]])
  local newm = misc.getmetrics()
  print("gc_steps_atomic = " .. newm.gc_steps_atomic - oldm.gc_steps_atomic)
  print("gc_steps_finalize = " .. newm.gc_steps_finalize - oldm.gc_steps_finalize)
  print("gc_steps_pause = " .. newm.gc_steps_pause - oldm.gc_steps_pause)
  print("gc_steps_propagate = " .. newm.gc_steps_propagate - oldm.gc_steps_propagate)
  print("gc_steps_sweep = " .. newm.gc_steps_sweep - oldm.gc_steps_sweep)
end
f()

And the display will show that the gc_steps_* metrics are not significantly different from what they would be if the box.execute() was absent.

Example with jit_trace_num and jit_trace_abort

Just-in-time compilers will «trace» code looking for opportunities to compile. jit_trace_abort can show how often there was a failed attempt (less is better), and jit_trace_num can show how many traces were generated since the last flush (usually more is better).

The following function does not contain code that can cause trouble for LuaJIT:

function f()
  jit.flush()
  for i = 1, 10 do collectgarbage("collect") end
  local oldm = misc.getmetrics()
  collectgarbage("collect")
  local sum = 0
  for i = 1, 57 do
    sum = sum + 57
  end
  for i = 1, 10 do collectgarbage("collect") end
  local newm = misc.getmetrics()
  print("trace_num = " .. newm.jit_trace_num - oldm.jit_trace_num)
  print("trace_abort = " .. newm.jit_trace_abort - oldm.jit_trace_abort)
end
f()

The result is: trace_num = 1, trace_abort = 0. Fine.

The following function seemingly does contain code that can cause trouble for LuaJIT:

jit.opt.start(0, "hotloop=2", "hotexit=2", "minstitch=15")
_G.globalthing = 5
function f()
  jit.flush()
  collectgarbage("collect")
  local oldm = misc.getmetrics()
  collectgarbage("collect")
  local sum = 0
  for i = 1, box.space._vindex:count()+ _G.globalthing do
    box.execute([[SELECT RANDOMBLOB(0);]])
    require('buffer').ibuf()
    _G.globalthing = _G.globalthing - 1
  end
  local newm = misc.getmetrics()
  print("trace_num = " .. newm.jit_trace_num - oldm.jit_trace_num)
  print("trace_abort = " .. newm.jit_trace_abort - oldm.jit_trace_abort)
end
f()

The result is: trace_num = between 2 and 4, trace_abort = 1. This means that up to four traces needed to be generated instead of one, and this means that something made LuaJIT give up in despair. Tracing more will reveal that the problem is not the suspicious-looking statements within the function, it is the jit.opt.start call. (A look at a jit.dump file might help in examining the trace compilation process.)

Example with jit_snap_restore and a performance unoptimization

If the slope curves of the jit_snap_restore metric grow after changes to old code, that can mean LuaJIT is stopping trace execution more frequently, and that can mean performance is degraded.

Start with this code:

function f()
  local function foo(i)
    return i <= 5 and i or tostring(i)
  end
  -- minstitch option needs to emulate nonstitching behaviour
  jit.opt.start(0, "hotloop=2", "hotexit=2", "minstitch=15")
  local sum = 0
  local oldm = misc.getmetrics()
  for i = 1, 10 do
    sum = sum + foo(i)
  end
  local newm = misc.getmetrics()
  local diff = newm.jit_snap_restore - oldm.jit_snap_restore
  print("diff = " .. diff)
end
f()

The result will be: diff = 3, because there is one side exit when the loop ends, and there are two side exits to the interpreter before LuaJIT may decide that the chunk of code is «hot» (the default value of the hotloop parameter is 56 according to Running LuaJIT).

And now change only one line within function local foo, so now the code is:

function f()
  local function foo(i)
    -- math.fmod is not yet compiled!
    return i <= 5 and i or math.fmod(i, 11)
  end
  -- minstitch option needs to emulate nonstitching behaviour
  jit.opt.start(0, "hotloop=2", "hotexit=2", "minstitch=15")
  local sum = 0
  local oldm = misc.getmetrics()
  for i = 1, 10 do
    sum = sum + foo(i)
  end
  local newm = misc.getmetrics()
  local diff = newm.jit_snap_restore - oldm.jit_snap_restore
  print("diff = " .. diff)
end
f()

The result will be: diff is larger, because there are more side exits. So this test indicates that changing the code affected the performance.

Администрирование

Tarantool устроен таким образом, что возможно запустить несколько экземпляров программы на одном компьютере.

Здесь мы показываем, как администрировать экземпляры Tarantool с помощью любой из следующих утилит:

Примечание

Эта глава включает в себя следующие разделы:

Managing modules

This section covers the installation and reloading of Tarantool modules. To learn about writing your own module and contributing it, check the Contributing a module section.

Установка модуля

Модули на Lua и C от разработчиков Tarantool и сторонних разработчиков доступны здесь:

Установка модуля из репозитория

Для получения подробной информации см. README в репозитории tarantool/rocks.

Установка модуля из deb/rpm

Выполните следующие действия:

  1. Установите Tarantool в соответствии с рекомендациями на странице загрузки.

  2. Install the module you need. Look up the module’s name on Tarantool rocks page and put the prefix «tarantool-» before the module name to avoid ambiguity:

    $ # для Ubuntu/Debian:
$ sudo apt-get install tarantool-<module-name>

$ # для RHEL/CentOS/Amazon:
$ sudo yum install tarantool-<module-name>

    Например, чтобы установить модуль vshard на Ubuntu, введите:

    $ sudo apt-get install tarantool-vshard

Теперь можно:

  • загружать любой модуль с помощью

    tarantool> name = require('module-name')

    например:

    tarantool> vshard = require('vshard')

  • локально находить установленные модули с помощью package.path (Lua) или package.cpath (C):

    tarantool> package.path
---
- ./?.lua;./?/init.lua; /usr/local/share/tarantool/?.lua;/usr/local/share/
tarantool/?/init.lua;/usr/share/tarantool/?.lua;/usr/share/tarantool/?/ini
t.lua;/usr/local/share/lua/5.1/?.lua;/usr/local/share/lua/5.1/?/init.lua;/
usr/share/lua/5.1/?.lua;/usr/share/lua/5.1/?/init.lua;
...

tarantool> package.cpath
---
- ./?.so;/usr/local/lib/x86_64-linux-gnu/tarantool/?.so;/usr/lib/x86_64-li
nux-gnu/tarantool/?.so;/usr/local/lib/tarantool/?.so;/usr/local/lib/x86_64
-linux-gnu/lua/5.1/?.so;/usr/lib/x86_64-linux-gnu/lua/5.1/?.so;/usr/local/
lib/lua/5.1/?.so;
...

    Примечание

    Знаки вопроса стоят вместо имени модуля, которое было указано ранее при вызове require('module-name').

Перезагрузка модуля

Любое приложение или модуль Tarantool можно перезагрузить с нулевым временем простоя.

Перезагрузка модуля на Lua

Ниже представлен пример, который иллюстрирует наиболее типичный случай – «обновление и перезагрузка».

Примечание

In this example, we use recommended administration practices based on instance files and tt utility.

  1. Обновите файлы приложения.

    Например, модуль в /usr/share/tarantool/app.lua:

    local function start()
  -- начальная версия
  box.once("myapp:v1.0", function()
    box.schema.space.create("somedata")
    box.space.somedata:create_index("primary")
    ...
  end)

  -- код миграции с 1.0 на 1.1
  box.once("myapp:v1.1", function()
    box.space.somedata.index.primary:alter(...)
    ...
  end)

  -- код миграции с 1.1 на 1.2
  box.once("myapp:v1.2", function()
    box.space.somedata.index.primary:alter(...)
    box.space.somedata:insert(...)
    ...
  end)
end

-- запустить файберы в фоновом режиме, если необходимо

local function stop()
  -- остановить все файберы, работающие в фоновом режиме, и очистить ресурсы
end

local function api_for_call(xxx)
  -- сделать что-то
end

return {
  start = start,
  stop = stop,
  api_for_call = api_for_call
}

  2. Обновить файл экземпляра.

    Например, /etc/tarantool/instances.enabled/my_app.lua:

    #!/usr/bin/env tarantool
--
-- пример горячей перезагрузки кода
--

box.cfg({listen = 3302})

-- ВНИМАНИЕ: правильно выполните разгрузку!
local app = package.loaded['app']
if app ~= nil then
  -- остановите старую версию приложения
  app.stop()
  -- разгрузите приложение
  package.loaded['app'] = nil
  -- разгрузите все зависимости
  package.loaded['somedep'] = nil
end

-- загрузите приложение
log.info('require app')
app = require('app')

-- запустите приложение
app.start({some app options controlled by sysadmins})

    Самое главное – правильно разгрузить приложение и его зависимости.

  3. Вручную перезагрузите файл приложения.

    For example, using tt:

    $ tt connect my_app -f /etc/tarantool/instances.enabled/my_app.lua

Перезагрузка модуля на С

После компиляции новой версии модуля на C (библиотека общего пользования *.so), вызовите функцию box.schema.func.reload(„module-name“) из Lua-скрипта для перезагрузки модуля.

Журналирование

Each Tarantool instance logs important events to its own log file. For instances started with tt, the log location is defined by the log_dir parameter in the tt configuration. By default, it’s /var/log/tarantool in the tt system mode, and the var/log subdirectory of the tt working directory in the local mode. In the specified location, tt creates separate directories for each instance’s logs.

To check how logging works, write something to the log using the log module:

$ tt connect application
   • Connecting to the instance...
   • Connected to application

application> require('log').info("Hello for the manual readers")
---
...

Затем проверим содержимое журнала:

$ tail instances.enabled/application/var/log/instance001/tt.log
2024-04-09 17:34:29.489 [49502] main/106/gc I> wal/engine cleanup is resumed
2024-04-09 17:34:29.489 [49502] main/104/interactive/box.load_cfg I> set 'instance_name' configuration option to "instance001"
2024-04-09 17:34:29.489 [49502] main/104/interactive/box.load_cfg I> set 'custom_proc_title' configuration option to "tarantool - instance001"
2024-04-09 17:34:29.489 [49502] main/104/interactive/box.load_cfg I> set 'log_nonblock' configuration option to false
2024-04-09 17:34:29.489 [49502] main/104/interactive/box.load_cfg I> set 'replicaset_name' configuration option to "replicaset001"
2024-04-09 17:34:29.489 [49502] main/104/interactive/box.load_cfg I> set 'listen' configuration option to [{"uri":"127.0.0.1:3301"}]
2024-04-09 17:34:29.489 [49502] main/107/checkpoint_daemon I> scheduled next checkpoint for Tue Apr  9 19:08:04 2024
2024-04-09 17:34:29.489 [49502] main/104/interactive/box.load_cfg I> set 'metrics' configuration option to {"labels":{"alias":"instance001"},"include":["all"],"exclude":[]}
2024-04-09 17:34:29.489 [49502] main I> entering the event loop
2024-04-09 17:34:38.905 [49502] main/116/console/unix/:/tarantool I> Hello for the manual readers

Log rotation

When logging to a file, the system administrator must ensure logs are rotated timely and do not take up all the available disk space. The recommended way to prevent log files from growing infinitely is using an external log rotation program, for example, logrotate, which is pre-installed on most mainstream Linux distributions.

A Tarantool log rotation configuration for logrotate can look like this:

# /var/log/tarantool/<env>/<app>/<instance>/*.log
/var/log/tarantool/*/*/*/*.log {
    daily
    size 512k
    missingok
    rotate 10
    compress
    delaycompress
    sharedscripts # Run tt logrotate only once after all logs are rotated.
    postrotate
        /usr/bin/tt -S logrotate
    endscript
}

In this configuration, tt logrotate is called after each log rotation to reopen the instance log files after they are moved by the logrotate program.

There is also the built-in function log.rotate(), which you can call on an instance to reopen its log file after rotation.

Log destination

Tarantool can write its logs to a log file, to syslog, or to a specified program through a pipe. For example, to send logs to syslog, specify the log.to parameter as follows:

log:
  to: syslog
  syslog:
    server: '127.0.0.1:514'

Безопасность

Tarantool разрешает два типа подключений:

Если вы подключены к административной консоли:

Поэтому порты для административной консоли следует настраивать очень осторожно. Если это TCP-порт, он должен быть открыть только для определенного IP-адреса. В идеале вместо TCP-порта лучше настроить доменный Unix-сокет, который требует наличие прав доступа к серверной машине. Тогда типичная настройка порта для административной консоли будет выглядеть следующим образом:

console.listen('/var/lib/tarantool/socket_name.sock')

а типичный URI для соединения будет таким:

/var/lib/tarantool/socket_name.sock

if the listener has the privilege to write on /var/lib/tarantool and the connector has the privilege to read on /var/lib/tarantool. Alternatively, to connect to an admin console of an instance started with tt, use tt connect.

Выяснить, является ли некоторый TCP-порт портом для административной консоли, можно с помощью telnet. Например:

$ telnet 0 3303
Trying 0.0.0.0...
Connected to 0.
Escape character is '^]'.
Tarantool 2.1.0 (Lua console)
type 'help' for interactive help

В этом примере в ответе от сервера нет слова «binary» и есть слова «Lua console». Это значит, что мы успешно подключились к порту для административной консоли и можем вводить администраторские запросы на этом терминале.

Если вы подключены к бинарному порту:

For ease of use, tt connect command automatically detects the type of connection during handshake and uses EVAL binary protocol command when it’s necessary to execute Lua commands over a binary connection. To execute EVAL, the authenticated user must have global «EXECUTE» privilege.

Поэтому при невозможности подключиться к машине по ssh системный администратор может получить удаленный доступ к экземпляру, создав пользователя Tarantool с глобальными «EXECUTE»-правами и непустым паролем.

Управление доступом

Tarantool enables flexible management of access to various database resources. The main concepts of Tarantool access control system are as follows:

Overview

Пользователи

A user identifies a person or program that interacts with a Tarantool instance. There might be different types of users, for example:

  • A database administrator responsible for the overall management and administration of a database. An administrator can create other users and grant them specified privileges.
  • A user with limited access to certain data and stored functions. Such users can get their privileges from the database administrator.
  • Users used in communications between Tarantool instances. For example, such users can be created to maintain replication and sharding in a Tarantool cluster.

There are two built-in users in Tarantool:

  • admin is a user with all available administrative privileges. If the connection uses an admin-console port, the current user is admin. For example, admin is used when connecting to an instance using tt connect locally using the instance name:

    $ tt connect app:instance001

    To allow remote binary port connections using the admin user, you need to set a password.

  • guest is a user with minimum privileges used by default for remote binary port connections. For example, guest is used when connecting to an instance using tt connect using the IP address and port without specifying the name of a user:

    $ tt connect 192.168.10.10:3301

    Предупреждение

    Given that the guest user allows unauthenticated access to Tarantool instances, it is not recommended to grant additional privileges to this user. For example, granting the execute access to universe allows remote code execution on instances.

Примечание

Information about users is stored in the _user space.

Пароли

Any user (except guest) may have a password. If a password is not set, a user cannot connect to Tarantool instances.

Tarantool password hashes are stored in the _user system space. By default, Tarantool uses the CHAP protocol to authenticate users and applies SHA-1 hashing to passwords. So, if the password is „123456“, the stored hash is a string like „a7SDfrdDKRBe5FaN2n3GftLKKtk=“. In the Enterprise Edition, you can enable PAP authentication with the SHA256 hashing algorithm.

Tarantool Enterprise Edition allows you to improve database security by enforcing the use of strong passwords, setting up a maximum password age, and so on. Learn more from the Authentication topic.

Objects

An object is a securable entity to which access can be granted. Tarantool has a number of objects that enable flexible management of access to data, stored functions, specific actions, and so on.

Below are a few examples of objects:

  • universe represents a database (box.schema) that contains database objects, including spaces, indexes, users, roles, sequences, and functions. Granting privileges to universe gives a user access to any object in a database.
  • space enables granting privileges to user-created or system spaces.
  • function enables granting privileges to functions.

Примечание

The full list of object types is available in the Object types section.

Privileges

The privileges granted to a user determine which operations the user can perform, for example:

  • The read and write permissions granted to the space object allow a user to read or modify data in the specified space.
  • The create permission granted to the space object allows a user to create new spaces.
  • The execute permission granted to the function object allows a user to execute the specified function.
  • The session permission granted to a user allows connecting to an instance over IPROTO.

Note that some privileges might require read and write access to certain system spaces. For example, the create permission granted to the space object requires read and write permissions to the _space system space. Similarly, granting the ability to create functions requires read and write access to the _func space.

Примечание

Information about privileges is stored in the _priv space.

Роли

A role is a container for privileges that can be granted to users. Roles can also be assigned to other roles, creating a role hierarchy.

There are the following built-in roles in Tarantool:

  • super has all available administrative permissions.

  • public has certain read permissions. This role is automatically granted to new users when they are created.

  • replication can be granted to a user used to maintain replication in a cluster.

  • sharding can be granted to a user used to maintain sharding in a cluster.

    Примечание

    The sharding role is created only if an instance is managed using YAML configuration.

Below are a few diagrams that demonstrate how privileges can be granted to a user without and with using roles.

  • In this example, a user gets privileges directly without using roles.

    user1 ── privilege1
    ├─── privilege2
    └─── privilege3

  • In this example, a user gets all privileges provided by role1 and specific privileges assigned directly.

    user1 ── role1 ── privilege1
    │        └─── privilege2
    ├─── privilege3
    └─── privilege4

  • In this example, role2 is granted to role1. This means that a user with role1 subsequently gets all privileges from both roles role1 and role2.

    user1 ── role1 ── privilege1
    │        ├─── privilege2
    │        └─── role2
    │                 ├─── privilege3
    │                 └─── privilege4
    ├─── privilege5
    └─── privilege6

Примечание

Information about roles is stored in the _user space.

Object owners

An owner of a database object is the user who created it. The owner of the database and the owner of objects that are created initially (the system spaces and the default users) is the admin user.

Owners automatically have privileges for objects they create. They can share these privileges with other users or roles using box.schema.user.grant() and box.schema.role.grant().

Примечание

Information about users who gave the specified privileges is stored in the _priv space.

Sessions

A session is the state of a connection to Tarantool. The session contains:

  • An integer ID identifying the connection.
  • The current user associated with the connection.
  • The text description of the connected peer.
  • A session’s local state, such as Lua variables and functions.

In Tarantool, a single session can execute multiple concurrent transactions. Each transaction is identified by a unique integer ID, which can be queried at the start of the transaction using box.session.sync().

Примечание

Чтобы отследить все подключения и отключения, можно использовать триггеры соединений и аутентификации.

Managing users

Creating a user

To create a new user, call box.schema.user.create(). In the example below, a user is created without a password:

box.schema.user.create('testuser')

In this example, the password is specified in the options parameter:

box.schema.user.create('testuser', { password = 'foobar' })

Changing passwords

To set or change a user’s password, use box.schema.user.passwd(). In the example below, a user password is set for a currently logged-in user:

box.schema.user.passwd('foobar')

To set the password for the specified user, pass a username and password as shown below:

box.schema.user.passwd('testuser', 'foobar')

Примечание

box.schema.user.password() returns a hash of the specified password.

Granting privileges to a user

To grant the specified privileges to a user, use the box.schema.user.grant() function. In the example below, testuser gets read permissions to the writers space and read/write permissions to the books space:

box.schema.user.grant('testuser', 'read', 'space', 'writers')
box.schema.user.grant('testuser', 'read,write', 'space', 'books')

Learn more about granting privileges to different types of objects from Granting privileges.

Getting a user’s information

To check whether the specified user exists, call box.schema.user.exists():

box.schema.user.exists('testuser')
--[[
- true
--]]

To get information about privileges granted to a user, call box.schema.user.info():

box.schema.user.info('testuser')
--[[
- - - execute
    - role
    - public
  - - read
    - space
    - writers
  - - read,write
    - space
    - books
  - - session,usage
    - universe
    -
  - - alter
    - user
    - testuser
--]]

In the example above, testuser has the following privileges:

  • The execute permission to the public role means that this role is assigned to the user.
  • The read permission to the writers space means that the user can read data from this space.
  • The read,write permissions to the books space mean that the user can read and modify data in this space.
  • The session,usage permissions to universe mean the following:
    • session: the user can authenticate over an IPROTO connection.
    • usage: lets the user use their privileges on database objects (for example, read and modify data in a space).
  • The alter permission lets testuser modify its own settings, for example, a password.

Revoking user’s privileges

To revoke the specified privileges, use the box.schema.user.revoke() function. In the example below, write access to the books space is revoked:

box.schema.user.revoke('testuser', 'write', 'space', 'books')

Revoking the session permission to universe can be used to disallow a user to connect to a Tarantool instance:

box.schema.user.revoke('testuser', 'session', 'universe')

Changing the current user

The current user name can be found using box.session.user().

box.session.user()
--[[
- admin
--]]

Текущего пользователя можно изменить:

  • For an admin-console connection: using box.session.su():

    box.session.su('testuser')
box.session.user()
--[[
- testuser
--]]

  • For a binary port connection: using the AUTH protocol command, supported by most clients.

  • For a binary-port connection invoking a stored function with the CALL command: if the SETUID property is enabled for the function, Tarantool temporarily replaces the current user with the function’s creator, with all the creator’s privileges, during function execution.

Dropping users

To drop the specified user, call box.schema.user.drop():

box.schema.user.drop('testuser')

Managing roles

Creating a role

To create a new role, call box.schema.role.create(). In the example below, two roles are created:

box.schema.role.create('books_space_manager')
box.schema.role.create('writers_space_reader')

Granting privileges to a role

To grant the specified privileges to a role, use the box.schema.role.grant() function. In the example below, the books_space_manager role gets read and write permissions to the books space:

box.schema.role.grant('books_space_manager', 'read,write', 'space', 'books')

The writers_space_reader role gets read permissions to the writers space:

box.schema.role.grant('writers_space_reader', 'read', 'space', 'writers')

Learn more about granting privileges to different types of objects from Granting privileges.

Примечание

Not all privileges can be granted to roles. Learn more from Permissions.

Granting a role to a role

Roles can be assigned to other roles. In the example below, the newly created all_spaces_manager role gets all privileges granted to books_space_manager and writers_space_reader:

box.schema.role.create('all_spaces_manager')
box.schema.role.grant('all_spaces_manager', 'books_space_manager')
box.schema.role.grant('all_spaces_manager', 'writers_space_reader')

Granting a role to a user

To grant the specified role to a user, use the box.schema.user.grant() function. In the example below, testuser gets privileges granted to the books_space_manager and writers_space_reader roles:

box.schema.user.grant('testuser', 'books_space_manager')
box.schema.user.grant('testuser', 'writers_space_reader')

Getting a role’s information

To check whether the specified role exists, call box.schema.role.exists():

box.schema.role.exists('books_space_manager')
--[[
- true
--]]

To get information about privileges granted to a role, call box.schema.role.info():

box.schema.role.info('books_space_manager')
--[[
- - - read,write
    - space
    - books
--]]

If a role has the execute permission to other roles, this means that these roles are granted to this parent role:

box.schema.role.info('all_spaces_manager')
--[[
- - - execute
    - role
    - books_space_manager
  - - execute
    - role
    - writers_space_reader
--]]

Revoking a role from a user

To revoke the specified role from a user, revoke the execute privilege for this role using the box.schema.user.revoke() function. In the example below, the books_space_reader role is revoked from testuser:

box.schema.user.revoke('testuser', 'execute', 'role', 'writers_space_reader')

To revoke role’s privileges, use box.schema.role.revoke().

Dropping roles

To drop the specified role, call box.schema.role.drop():

box.schema.role.drop('writers_space_reader')

Granting privileges

To grant the specified privileges to a user or role, use the box.schema.user.grant() and box.schema.role.grant() functions, which have similar signatures and accept the same set of arguments. For example, the box.schema.user.grant() signature looks as follows:

box.schema.user.grant(username, permissions, object-type, object-name[, {options}])

Any object

In the example below, testuser gets privileges allowing them to create any object of any type:

box.schema.user.grant('testuser','read,write,create','universe')

In this example, testuser can grant access to objects that testuser created:

box.schema.user.grant('testuser','write','space','_priv')

Spaces

Creating and altering spaces

In the example below, testuser gets privileges allowing them to create spaces:

box.schema.user.grant('testuser','create','space')
box.schema.user.grant('testuser','write', 'space', '_schema')
box.schema.user.grant('testuser','write', 'space', '_space')

As you can see, the ability to create spaces also requires write access to certain system spaces.

To allow testuser to drop a space that has associated objects, add the following privileges:

box.schema.user.grant('testuser','create,drop','space')
box.schema.user.grant('testuser','write','space','_schema')
box.schema.user.grant('testuser','write','space','_space')
box.schema.user.grant('testuser','write','space','_space_sequence')
box.schema.user.grant('testuser','read','space','_trigger')
box.schema.user.grant('testuser','read','space','_fk_constraint')
box.schema.user.grant('testuser','read','space','_ck_constraint')
box.schema.user.grant('testuser','read','space','_func_index')

Creating and altering indexes

In the example below, testuser gets privileges allowing them to create indexes in the „writers“ space:

box.schema.user.grant('testuser','create,read','space','writers')
box.schema.user.grant('testuser','read,write','space','_space_sequence')
box.schema.user.grant('testuser','write', 'space', '_index')

To allow testuser to alter indexes in the writers space, grant the privileges below. This example assumes that indexes in the writers space are not created by testuser.

box.schema.user.grant('testuser','alter','space','writers')
box.schema.user.grant('testuser','read','space','_space')
box.schema.user.grant('testuser','read','space','_index')
box.schema.user.grant('testuser','read','space','_space_sequence')
box.schema.user.grant('testuser','write','space','_index')

If testuser created indexes in the writers space, granting the following privileges is enough to alter indexes:

box.schema.user.grant('testuser','read','space','_space_sequence')
box.schema.user.grant('testuser','read,write','space','_index')

CRUD operations

In this example, testuser gets privileges allowing them to select data from the „writers“ space:

box.schema.user.grant('testuser','read','space','writers')

In this example, testuser is allowed to read and modify data in the „books“ space:

box.schema.user.grant('testuser','read,write','space','books')

Sequences

Creating and dropping sequences

In this example, testuser gets privileges to create sequence generators:

box.schema.user.grant('testuser','create','sequence')
box.schema.user.grant('testuser', 'read,write', 'space', '_sequence')

To let testuser drop a sequence, grant them the following privileges:

box.schema.user.grant('testuser','drop','sequence')
box.schema.user.grant('testuser','write','space','_sequence_data')
box.schema.user.grant('testuser','write','space','_sequence')

Using sequence functions

In this example, testuser is allowed to use the id_seq:next() function with a sequence named „id_seq“:

box.schema.user.grant('testuser','read,write','sequence','id_seq')

In the next example, testuser is allowed to use the id_seq:set() or id_seq:reset() functions with a sequence named „id_seq“:

box.schema.user.grant('testuser','write','sequence','id_seq')

Functions

Creating and dropping functions

In this example, testuser gets privileges to create functions:

box.schema.user.grant('testuser','create','function')
box.schema.user.grant('testuser','read,write','space','_func')

To let testuser drop a function, grant them the following privileges:

box.schema.user.grant('testuser','drop','function')
box.schema.user.grant('testuser','write','space','_func')

Executing functions

To give the ability to execute a function named „sum“, grant the following privileges:

box.schema.user.grant('testuser','execute','function','sum')

Пользователи

In this example, testuser gets privileges to create other users:

box.schema.user.grant('testuser','create','user')
box.schema.user.grant('testuser', 'read,write', 'space', '_user')
box.schema.user.grant('testuser', 'write', 'space', '_priv')

Роли

To let testuser create new roles, grant the following privileges:

box.schema.user.grant('testuser','create','role')
box.schema.user.grant('testuser', 'read,write', 'space', '_user')
box.schema.user.grant('testuser', 'write', 'space', '_priv')

Executing code

To let testuser execute Lua code, grant the execute privilege to the lua_eval object:

box.schema.user.grant('testuser','execute','lua_eval')

Similarly, executing an arbitrary SQL expression requires the execute privilege to the sql object:

box.schema.user.grant('testuser','execute','sql')

Example

In the example below, the created Lua function is executed on behalf of its creator, even if called by another user.

First, the two spaces (space1 and space2) are created, and a no-password user (private_user) is granted full access to them. Then read_and_modify is defined and private_user becomes this function’s creator. Finally, another user (public_user) is granted access to execute Lua functions created by private_user.

box.schema.space.create('space1')
box.schema.space.create('space2')
box.space.space1:create_index('pk')
box.space.space2:create_index('pk')

box.schema.user.create('private_user')

box.schema.user.grant('private_user', 'read,write', 'space', 'space1')
box.schema.user.grant('private_user', 'read,write', 'space', 'space2')
box.schema.user.grant('private_user', 'create', 'universe')
box.schema.user.grant('private_user', 'read,write', 'space', '_func')

function read_and_modify(key)
  local space1 = box.space.space1
  local space2 = box.space.space2
  local fiber = require('fiber')
  local t = space1:get{key}
  if t ~= nil then
    space1:put{key, box.session.uid()}
    space2:put{key, fiber.time()}
  end
end

box.session.su('private_user')
box.schema.func.create('read_and_modify', {setuid= true})
box.session.su('admin')
box.schema.user.create('public_user', {password = 'secret'})
box.schema.user.grant('public_user', 'execute', 'function', 'read_and_modify')

Whenever public_user calls the function, it is executed on behalf of its creator, private_user.

All object types and permissions

Object types

Object type Description
universe A database (box.schema) that contains database objects, including spaces, indexes, users, roles, sequences, and functions. Granting privileges to universe gives a user access to any object in the database.
user A user.
role A role.
space A space.
function A function.
sequence A sequence.
lua_eval Executing arbitrary Lua code.
lua_call Calling any global user-defined Lua function.
sql Executing an arbitrary SQL expression.

Permissions

Permission Object type Granted to roles Description
read All Yes Allows reading data of the specified object. For example, this permission can be used to allow a user to select data from the specified space.
write All Yes Allows updating data of the specified object. For example, this permission can be used to allow a user to modify data in the specified space.
create All Yes

Allows creating objects of the specified type. For example, this permission can be used to allow a user to create new spaces.

Note that this permission requires read and write access to certain system spaces.
alter All Yes

Allows altering objects of the specified type.

Note that this permission requires read and write access to certain system spaces.
drop All Yes

Allows dropping objects of the specified type.

Note that this permission requires read and write access to certain system spaces.
execute role, universe, function, lua_eval, lua_call, sql Yes For role, allows using the specified role. For other object types, allows calling a function.
session universe No Allows a user to connect to an instance over IPROTO.
usage universe No Allows a user to use their privileges on database objects (for example, read, write, and alter spaces).

Object types and permissions

Object type Details
universe
  • read: Allows reading any object types, including all spaces or sequence objects.
  • write: Allows modifying any object types, including all spaces or sequence objects.
  • execute: Allows execute functions, Lua code, or SQL expressions, including IPROTO calls.
  • session: Allows a user to connect to an instance over IPROTO.
  • usage: Allows a user to use their privileges on database objects (for example, read, write, and alter space).
  • create: Allows creating users, roles, functions, spaces, and sequences. This permission requires read and write access to certain system spaces.
  • drop: Allows creating users, roles, functions, spaces, and sequences. This permission requires read and write access to certain system spaces.
  • alter: Allows altering user settings or space objects.
user
  • alter: Allows modifying a user description, for example, change the password.
  • create: Allows creating new users. This permission requires read and write access to the _user system space.
  • drop: Allows dropping users. This permission requires read and write access to the _user system space.
role
  • execute: Indicates that a role is assigned to the user or another role.
  • create: Allows creating new roles. This permission requires read and write access to the _user system space.
  • drop: Allows dropping roles. This permission requires read and write access to the _user system space.
space

  • read: Allows selecting data from a space.

  • write: Allows modifying data in a space.

  • create: Allows creating new spaces. This permission requires read and write access to the _space system space.

  • drop: Allows dropping spaces. This permission requires read and write access to the _space system space.

  • alter: Allows modifying spaces. This permission requires read and write access to the _space system space.

    If a space is created by a user, they can read and write it without granting explicit permission.
function

  • execute: Allows calling a function.

  • create: Allows creating a function. This permission requires read and write access to the _func system space.

    If a function is created by a user, they can execute it without granting explicit permission.

  • drop: Allows dropping a function. This permission requires read and write access to the _func system space.
sequence

  • read: Allows using sequences in space_obj:create_index().

  • write: Allows all operations for a sequence object.

    seq_obj:drop() requires a write permission to the _priv system space.

  • create: Allows creating sequences. This permission requires read and write access to the _sequence system space.

    If a sequence is created by a user, they can read/write it without explicit permission.

  • drop: Allows dropping sequences. This permission requires read and write access to the _sequence system space.

  • alter: Has no effect. seq_obj:alter() and other methods require the write permission.
lua_eval
  • execute: Allows executing arbitrary Lua code using the IPROTO_EVAL request.
lua_call
  • execute: Allows executing any user-defined function using the IPROTO_CALL request. This permission doesn’t allow a user to call built-in Lua functions (for example, loadstring() or box.session.su()) and functions defined in the _func system space.
sql
  • execute: Allows executing arbitrary SQL expression using the IPROTO_PREPARE and IPROTO_EXECUTE requests.

Replication administration

Мониторинг набора реплик

To learn what instances belong to the replica set and obtain statistics for all these instances, execute a box.info.replication request. The output below shows the replication status for a replica set containing one master and two replicas:

manual_leader:instance001> box.info.replication
---
- 1:
    id: 1
    uuid: 9bb111c2-3ff5-36a7-00f4-2b9a573ea660
    lsn: 21
    name: instance001
  2:
    id: 2
    uuid: 4cfa6e3c-625e-b027-00a7-29b2f2182f23
    lsn: 0
    upstream:
      status: follow
      idle: 0.052655000000414
      peer: replicator@127.0.0.1:3302
      lag: 0.00010204315185547
    name: instance002
    downstream:
      status: follow
      idle: 0.09503500000028
      vclock: {1: 21}
      lag: 0.00026917457580566
  3:
    id: 3
    uuid: 9a3a1b9b-8a18-baf6-00b3-a6e5e11fd8b6
    lsn: 0
    upstream:
      status: follow
      idle: 0.77522099999987
      peer: replicator@127.0.0.1:3303
      lag: 0.0001838207244873
    name: instance003
    downstream:
      status: follow
      idle: 0.33186100000012
      vclock: {1: 21}
      lag: 0
        ...

The following diagram illustrates the upstream and downstream connections if box.info.replication executed at the master instance (instance001):

replication status on master

If box.info.replication is executed on instance002, the upstream and downstream connections look as follows:

replication status on replica

This means that statistics for replicas are given in regard to the instance on which box.info.replication is executed.

Основные индикаторы работоспособности репликации:

Восстановление после сбоя

«Сбой» – это ситуация, когда мастер становится недоступен вследствие проблем с оборудованием, сетевых неполадок или программной ошибки.

../../../_images/mr-degraded.svg

The master’s upstream status is reported as disconnected when executing box.info.replication on a replica:

auto_leader:instance001> box.info.replication
---
- 1:
    id: 1
    uuid: 4cfa6e3c-625e-b027-00a7-29b2f2182f23
    lsn: 32
    upstream:
      peer: replicator@127.0.0.1:3302
      lag: 0.00032305717468262
      status: disconnected
      idle: 48.352504000002
      message: 'connect, called on fd 20, aka 127.0.0.1:62575: Connection refused'
      system_message: Connection refused
    name: instance002
    downstream:
      status: stopped
      message: 'unexpected EOF when reading from socket, called on fd 32, aka 127.0.0.1:3301,
        peer of 127.0.0.1:62204: Broken pipe'
      system_message: Broken pipe
  2:
    id: 2
    uuid: 9bb111c2-3ff5-36a7-00f4-2b9a573ea660
    lsn: 1
    name: instance001
  3:
    id: 3
    uuid: 9a3a1b9b-8a18-baf6-00b3-a6e5e11fd8b6
    lsn: 0
    upstream:
      status: follow
      idle: 0.18620999999985
      peer: replicator@127.0.0.1:3303
      lag: 0.00012516975402832
    name: instance003
    downstream:
      status: follow
      idle: 0.19718099999955
      vclock: {2: 1, 1: 32}
      lag: 0.00051403045654297
...

To learn how to perform manual failover in a master-replica set, see the Performing manual failover section.

In a master-replica configuration with automated failover, a new master should be elected automatically.

Перезагрузка реплики

If any of a replica’s write-ahead log or snapshot files are corrupted or deleted, you can reseed the replica. This procedure works only if the master’s write-ahead logs are present.

  1. Stop the replica using the tt stop command.

  2. Delete write-ahead logs and snapshots stored in the var/lib/<instance_name> directory.

    Примечание

    var/lib is the default directory used by tt to store write-ahead logs and snapshots. Learn more from Configuration.

  3. Start the replica using the tt start command. The replica should catch up with the master by retrieving all the master’s tuples.

  4. (Optional) If you’re reseeding a replica after a replication conflict, you also need to restart replication.

Решение конфликтов репликации

Tarantool guarantees that every update is applied only once on every replica. However, due to the asynchronous nature of replication, the order of updates is not guaranteed. This topic describes how to solve problems in master-master replication.

Замена по одному и тому же первичному ключу

Case 1: You have two instances of Tarantool. For example, you try to make a replace operation with the same primary key on both instances at the same time. This causes a conflict over which tuple to save and which one to discard.

Триггер-функции Тарантула могут помочь в реализации правил разрешения конфликтов при определенных условиях. Например, если у вас есть метка времени, то можно указать, что сохранять нужно кортеж с большей меткой.

First, you need a before_replace() trigger on the space which may have conflicts. In this trigger, you can compare the old and new replica records and choose which one to use (or skip the update entirely, or merge two records together).

Then you need to set the trigger at the right time before the space starts to receive any updates. The way you usually set the before_replace trigger is right when the space is created, so you need a trigger to set another trigger on the system space _space, to capture the moment when your space is created and set the trigger there. This can be an on_replace() trigger.

Разница между before_replace и on_replace заключается в том, что on_replace вызывается после вставки строки в спейс, а before_replace вызывается перед ней.

Устанавливать триггер _space:on_replace() также нужно в определенный момент. Лучшее время для его использования – это когда только что создан _space, что является триггером на box.ctl.on_schema_init().

You also need to utilize box.on_commit to get access to the space being created. The resulting snippet would be the following:

local my_space_name = 'my_space'
local my_trigger = function(old, new) ... end -- ваша функция, устраняющая конфликт
box.ctl.on_schema_init(function()
    box.space._space:on_replace(function(old_space, new_space)
        if not old_space and new_space and new_space.name == my_space_name then
            box.on_commit(function()
                box.space[my_space_name]:before_replace(my_trigger)
            end
        end
    end)
end)

Предотвращение дублирующей вставки

Case 2: In a replica set of two masters, both of them try to insert data by the same unique key:

tarantool> box.space.tester:insert{1, 'data'}

Это вызовет сообщение об ошибке дубликата ключа (Duplicate key exists in unique index 'primary' in space 'tester'), и репликация остановится. Такое поведение системы обеспечивается использованием рекомендуемого значения false (по умолчанию) для конфигурационного параметра replication_skip_conflict.

$ # сообщения об ошибках от мастера №1
2017-06-26 21:17:03.233 [30444] main/104/applier/rep_user@100.96.166.1 I> can't read row
2017-06-26 21:17:03.233 [30444] main/104/applier/rep_user@100.96.166.1 memtx_hash.cc:226 E> ER_TUPLE_FOUND:
Duplicate key exists in unique index 'primary' in space 'tester'
2017-06-26 21:17:03.233 [30444] relay/[::ffff:100.96.166.178]/101/main I> the replica has closed its socket, exiting
2017-06-26 21:17:03.233 [30444] relay/[::ffff:100.96.166.178]/101/main C> exiting the relay loop

$ # сообщения об ошибках от мастера №2
2017-06-26 21:17:03.233 [30445] main/104/applier/rep_user@100.96.166.1 I> can't read row
2017-06-26 21:17:03.233 [30445] main/104/applier/rep_user@100.96.166.1 memtx_hash.cc:226 E> ER_TUPLE_FOUND:
Duplicate key exists in unique index 'primary' in space 'tester'
2017-06-26 21:17:03.234 [30445] relay/[::ffff:100.96.166.178]/101/main I> the replica has closed its socket, exiting
2017-06-26 21:17:03.234 [30445] relay/[::ffff:100.96.166.178]/101/main C> exiting the relay loop

Если мы проверим статус репликации с помощью box.info, то увидим, что репликация на мастере №1 остановлена (1.upstream.status = stopped). Кроме того, данные с этого мастера не реплицируются (группа 1.downstream отсутствует в отчете), поскольку встречается та же ошибка:

# статусы репликации (отчет от мастера №3)
tarantool> box.info
---
- version: 1.7.4-52-g980d30092
  id: 3
  ro: false
  vclock: {1: 9, 2: 1000000, 3: 3}
  uptime: 557
  lsn: 3
  vinyl: []
  cluster:
    uuid: 34d13b1a-f851-45bb-8f57-57489d3b3c8b
  pid: 30445
  status: running
  signature: 1000012
  replication:
    1:
      id: 1
      uuid: 7ab6dee7-dc0f-4477-af2b-0e63452573cf
      lsn: 9
      upstream:
        peer: replicator@192.168.0.101:3301
        lag: 0.00050592422485352
        status: stopped
        idle: 445.8626639843
        message: Duplicate key exists in unique index 'primary' in space 'tester'
    2:
      id: 2
      uuid: 9afbe2d9-db84-4d05-9a7b-e0cbbf861e28
      lsn: 1000000
      upstream:
        status: follow
        idle: 201.99915885925
        peer: replicator@192.168.0.102:3301
        lag: 0.0015020370483398
      downstream:
        vclock: {1: 8, 2: 1000000, 3: 3}
    3:
      id: 3
      uuid: e826a667-eed7-48d5-a290-64299b159571
      lsn: 3
  uuid: e826a667-eed7-48d5-a290-64299b159571
...

To learn how to resolve a replication conflict by reseeding a replica, see Resolving replication conflicts.

Replication runs out of sync

Предположим, что мы выполняем следующую операцию в кластере из двух экземпляров с конфигурацией мастер-мастер:

tarantool> box.space.tester:upsert({1}, {{'=', 2, box.info.uuid}})

Когда эта операция применяется на обоих экземплярах в наборе реплик:

# на мастере #1
tarantool> box.space.tester:upsert({1}, {{'=', 2, box.info.uuid}})
# на мастере #2
tarantool> box.space.tester:upsert({1}, {{'=', 2, box.info.uuid}})

… можно получить следующие результаты в зависимости от порядка выполнения:

  • каждая строка мастера содержит UUID из мастера №1,
  • каждая строка мастера содержит UUID из мастера №2,
  • у мастера №1 UUID мастера №2, и наоборот.

Commutative changes

The cases described in the previous paragraphs represent examples of non-commutative operations, that is operations whose result depends on the execution order. On the contrary, for commutative operations, the execution order does not matter.

Рассмотрим, например, следующую команду:

tarantool> box.space.tester:upsert{{1, 0}, {{'+', 2, 1)}

Эта операция коммутативна: получаем одинаковый результат, независимо от порядка, в котором обновление применяется на других мастерах.

Trigger usage

The logic and the snippet setting a trigger will be the same here as in case 1. But the trigger function will differ. Note that the trigger below assumes that tuple has a timestamp in the second field.

local my_space_name = 'test'
local my_trigger = function(old, new, sp, op)
    -- op:  ‘INSERT’, ‘DELETE’, ‘UPDATE’, or ‘REPLACE’
    if new == nil then
        print("No new during "..op, old)
        return -- удаление допустимо
    end
    if old == nil then
        print("Insert new, no old", new)
        return new  -- вставка без старого значения допустима
    end
    print(op.." duplicate", old, new)
    if op == 'INSERT' then
        if new[2] > old[2] then
            -- Создание нового кортежа сменит оператор на REPLACE
            return box.tuple.new(new)
        end
        return old
    end
    if new[2] > old[2] then
        return new
    else
        return old
    end
    return
end

box.ctl.on_schema_init(function()
    box.space._space:on_replace(function(old_space, new_space)
        if not old_space and new_space and new_space.name == my_space_name then
            box.on_commit(function()
                box.space[my_space_name]:before_replace(my_trigger)
            end)
        end
    end)
end)

Просмотр состояния сервера

Использование Tarantool в качестве клиента

Tarantool входит в интерактивный режим, если:

Tarantool выводит приглашение командной строки (например, «tarantool>») – и вы можете посылать запросы. Если использовать Tarantool таким образом, он может выступать клиентом для удаленного сервера, см. простые примеры в Руководстве для начинающих.

The interactive mode is used in the tt utility’s connect command.

Выполнение кода на экземпляре Tarantool

You can attach to an instance’s admin console and execute some Lua code using tt:

$ # for local instances:
$ tt connect my_app
   • Connecting to the instance...
   • Connected to /var/run/tarantool/example.control

/var/run/tarantool/my_app.control> 1 + 1
---
- 2
...
/var/run/tarantool/my_app.control>

$ # for local and remote instances:
$ tt connect username:password@127.0.0.1:3306

You can also use tt to execute Lua code on an instance without attaching to its admin console. For example:

$ # executing commands directly from the command line
$ <command> | tt connect my_app -f -
<...>

$ # - OR -

$ # executing commands from a script file
$ tt connect my_app -f script.lua
<...>

Примечание

Alternatively, you can use the console module or the net.box module from a Tarantool server. Also, you can write your client programs with any of the connectors. However, most of the examples in this manual illustrate usage with either tt connect or using the Tarantool server as a client.

Проверка состояния экземпляра

To check the instance status, run:

$ tt status my_app
INSTANCE     STATUS      PID   MODE
my_app       RUNNING     67172 RW

$ # - OR -

$ systemctl status tarantool@my_app

To check the boot log, on systems with systemd, run:

$ journalctl -u tarantool@my_app -n 5

For more specific checks, use the reports provided by functions in the following submodules:

Finally, there is the metrics library, which enables collecting metrics (such as memory usage or number of requests) from Tarantool applications and expose them via various protocols, including Prometheus. Check Monitoring for more details.

Пример

Очень часто администраторам приходится вызывать функцию box.slab.info(), которая показывает подробную статистику по использованию памяти для конкретного экземпляра Tarantool.

tarantool> box.slab.info()
---
- items_size: 228128
  items_used_ratio: 1.8%
  quota_size: 1073741824
  quota_used_ratio: 0.8%
  arena_used_ratio: 43.2%
  items_used: 4208
  quota_used: 8388608
  arena_size: 2325176
  arena_used: 1003632
...

Tarantool занимает память операционной системы, например, когда пользователь вставляет много данных. Можно проверить, сколько памяти занято, выполнив команду (в Linux):

ps -eo args,%mem | grep "tarantool"

Tarantool почти никогда не освобождает эту память, даже если пользователь удалит все, что было вставлено, или уменьшит фрагментацию, вызвав сборщик мусора в Lua с помощью функции collectgarbage.

Как правило, это не влияет на производительность. Однако, чтобы заставить Tarantool высвободить память, можно вызвать :box.snapshot(), остановить экземпляр и перезапустить его.

Inspect traffic

Inspecting binary traffic is a boring task. We offer a Wireshark plugin to simplify the analysis of Tarantool’s traffic.

To enable the plugin, follow the steps below.

Clone the tarantool-dissector repository:

git clone https://github.com/tarantool/tarantool-dissector.git

Copy or symlink the plugin files into the Wireshark plugin directory:

mkdir -p ~/.local/lib/wireshark/plugins
cd ~/.local/lib/wireshark/plugins
ln -s /path/to/tarantool-dissector/MessagePack.lua ./
ln -s /path/to/tarantool-dissector/tarantool.dissector.lua ./

(For the location of the plugin directory on macOS and Windows, please refer to the Plugin folders chapter in the Wireshark documentation.)

Run the Wireshark GUI and ensure that the plugins are loaded:

Now you can inspect incoming and outgoing Tarantool packets with user-friendly annotations.

Visit the project page for details: https://github.com/tarantool/tarantool-dissector.

Профилирование производительности

Иногда Tarantool может работать медленнее, чем обычно. Причин такого поведения может быть несколько: проблемы с диском, Lua-скрипты, активно использующие процессор, или неправильная настройка. В таких случаях в журнале Tarantool’а могут отсутствовать необходимые подробности, поэтому единственным признаком неправильного поведения является наличие в журнале записей вида W> too long DELETE: 8.546 sec. Ниже приведены инструменты и приемы, которые облегчают снятие профиля производительности Tarantool’а. Эта процедура может помочь при решении проблем с замедлением.

Примечание

Большинство инструментов, за исключением fiber.info(), предназначено для дистрибутивов GNU/Linux, но не для FreeBSD или Mac OS.

fiber.info()

Самый простой способ профилирования – это использование встроенных функций Tarantool’а. fiber.info() возвращает информацию обо всех работающих файберах с соответствующей трассировкой стека для языка C. Эти данные показывают, сколько файберов запущенно на данный момент и какие функции, написанные на C, вызываются чаще остальных.

Сначала войдите в интерактивную административную консоль вашего экземпляра Tarantool’а:

$ tt connect NAME|URI

После этого загрузите модуль fiber:

tarantool> fiber = require('fiber')

Теперь можно получить необходимую информацию с помощью fiber.info().

На этом шаге в вашей консоли должно выводиться следующее:

tarantool> fiber = require('fiber')
---
...
tarantool> fiber.info()
---
- 360:
    csw: 2098165
    backtrace:
    - '#0 0x4d1b77 in wal_write(journal*, journal_entry*)+487'
    - '#1 0x4bbf68 in txn_commit(txn*)+152'
    - '#2 0x4bd5d8 in process_rw(request*, space*, tuple**)+136'
    - '#3 0x4bed48 in box_process1+104'
    - '#4 0x4d72f8 in lbox_replace+120'
    - '#5 0x50f317 in lj_BC_FUNCC+52'
    fid: 360
    memory:
      total: 61744
      used: 480
    name: main
  129:
    csw: 113
    backtrace: []
    fid: 129
    memory:
      total: 57648
      used: 0
    name: 'console/unix/:'
...

Мы рекомендуем присваивать создаваемым файберам понятные имена, чтобы их можно было легко найти в списке, выводимом fiber.info(). В примере ниже создается файбер с именем myworker:

tarantool> fiber = require('fiber')
---
...
tarantool> f = fiber.create(function() while true do fiber.sleep(0.5) end end)
---
...
tarantool> f:name('myworker') <!-- присваивание имени файберу
---
...
tarantool> fiber.info()
---
- 102:
    csw: 14
    backtrace:
    - '#0 0x501a1a in fiber_yield_timeout+90'
    - '#1 0x4f2008 in lbox_fiber_sleep+72'
    - '#2 0x5112a7 in lj_BC_FUNCC+52'
    fid: 102
    memory:
      total: 57656
      used: 0
    name: myworker <!-- новый созданный фоновый файбер
  101:
    csw: 284
    backtrace: []
    fid: 101
    memory:
      total: 57656
      used: 0
    name: interactive
...

Для принудительного завершения файбера используется команда fiber.kill(fid):

tarantool> fiber.kill(102)
---
...
tarantool> fiber.info()
---
- 101:
    csw: 324
    backtrace: []
    fid: 101
    memory:
      total: 57656
      used: 0
    name: interactive
...

Чтобы получить таблицу всех рабочих файберов, можно использовать fiber.top().

Если вам необходимо динамически получать информацию с помощью fiber.info(), вам может пригодиться приведенный ниже скрипт. Он каждые полсекунды подключается к экземпляру Tarantool’а, указанному в переменной NAME, выполняет команду fiber.info() и записывает ее выход в файл fiber-info.txt:

$ rm -f fiber.info.txt
$ watch -n 0.5 "echo 'require(\"fiber\").info()' | tt connect NAME -f - | tee -a fiber-info.txt"

Если вы не можете самостоятельно разобраться, какой именно файбер вызывает проблемы с производительностью, запустите данный скрипт на 10-15 секунд и пришлите получившийся файл команде Tarantool’а на адрес support@tarantool.org.

Простейшие профилировщики

pstack <pid>

Чтобы использовать этот инструмент, его необходимо установить с помощью пакетного менеджера, поставляемого с вашим дистрибутивом Linux. Данная команда выводит трассировку стека выполнения для работающего процесса с соответствующим PID. При необходимости команду можно запустить несколько раз, чтобы выявить узкое место, которое вызывает падение производительности.

После установки воспользуйтесь следующей командой:

$ pstack $(pidof tarantool INSTANCENAME.lua)

Затем выполните:

$ echo $(pidof tarantool INSTANCENAME.lua)

чтобы вывести на экран PID экземпляра Tarantool’а, использующего файл INSTANCENAME.lua.

В вашей консоли должно отображаться приблизительно следующее:

Thread 19 (Thread 0x7f09d1bff700 (LWP 24173)):
#0 0x00007f0a1a5423f2 in ?? () from /lib64/libgomp.so.1
#1 0x00007f0a1a53fdc0 in ?? () from /lib64/libgomp.so.1
#2 0x00007f0a1ad5adc5 in start_thread () from /lib64/libpthread.so.0
#3 0x00007f0a1a050ced in clone () from /lib64/libc.so.6
Thread 18 (Thread 0x7f09d13fe700 (LWP 24174)):
#0 0x00007f0a1a5423f2 in ?? () from /lib64/libgomp.so.1
#1 0x00007f0a1a53fdc0 in ?? () from /lib64/libgomp.so.1
#2 0x00007f0a1ad5adc5 in start_thread () from /lib64/libpthread.so.0
#3 0x00007f0a1a050ced in clone () from /lib64/libc.so.6
<...>
Thread 2 (Thread 0x7f09c8bfe700 (LWP 24191)):
#0 0x00007f0a1ad5e6d5 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x000000000045d901 in wal_writer_pop(wal_writer*) ()
#2 0x000000000045db01 in wal_writer_f(__va_list_tag*) ()
#3 0x0000000000429abc in fiber_cxx_invoke(int (*)(__va_list_tag*), __va_list_tag*) ()
#4 0x00000000004b52a0 in fiber_loop ()
#5 0x00000000006099cf in coro_init ()
Thread 1 (Thread 0x7f0a1c47fd80 (LWP 24172)):
#0 0x00007f0a1a0512c3 in epoll_wait () from /lib64/libc.so.6
#1 0x00000000006051c8 in epoll_poll ()
#2 0x0000000000607533 in ev_run ()
#3 0x0000000000428e13 in main ()

gdb -ex «bt» -p <pid>

Как и в случае с pstack, перед использованием GNU-отладчик (также известный как gdb) необходимо сначала установить через пакетный менеджер, встроенный в ваш дистрибутив Linux.

После установки воспользуйтесь следующей командой:

$ gdb -ex "set pagination 0" -ex "thread apply all bt" --batch -p $(pidof tarantool INSTANCENAME.lua)

Затем выполните:

$ echo $(pidof tarantool INSTANCENAME.lua)

чтобы вывести на экран PID экземпляра Tarantool’а, использующего файл INSTANCENAME.lua.

После использования отладчика в консоль должна выводиться следующая информация:

[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

[CUT]

Thread 1 (Thread 0x7f72289ba940 (LWP 20535)):
#0 _int_malloc (av=av@entry=0x7f7226e0eb20 <main_arena>, bytes=bytes@entry=504) at malloc.c:3697
#1 0x00007f7226acf21a in __libc_calloc (n=<optimized out>, elem_size=<optimized out>) at malloc.c:3234
#2 0x00000000004631f8 in vy_merge_iterator_reserve (capacity=3, itr=0x7f72264af9e0) at /usr/src/tarantool/src/box/vinyl.c:7629
#3 vy_merge_iterator_add (itr=itr@entry=0x7f72264af9e0, is_mutable=is_mutable@entry=true, belong_range=belong_range@entry=false) at /usr/src/tarantool/src/box/vinyl.c:7660
#4 0x00000000004703df in vy_read_iterator_add_mem (itr=0x7f72264af990) at /usr/src/tarantool/src/box/vinyl.c:8387
#5 vy_read_iterator_use_range (itr=0x7f72264af990) at /usr/src/tarantool/src/box/vinyl.c:8453
#6 0x000000000047657d in vy_read_iterator_start (itr=<optimized out>) at /usr/src/tarantool/src/box/vinyl.c:8501
#7 0x00000000004766b5 in vy_read_iterator_next (itr=itr@entry=0x7f72264af990, result=result@entry=0x7f72264afad8) at /usr/src/tarantool/src/box/vinyl.c:8592
#8 0x000000000047689d in vy_index_get (tx=tx@entry=0x7f7226468158, index=index@entry=0x2563860, key=<optimized out>, part_count=<optimized out>, result=result@entry=0x7f72264afad8) at /usr/src/tarantool/src/box/vinyl.c:5705
#9 0x0000000000477601 in vy_replace_impl (request=<optimized out>, request=<optimized out>, stmt=0x7f72265a7150, space=0x2567ea0, tx=0x7f7226468158) at /usr/src/tarantool/src/box/vinyl.c:5920
#10 vy_replace (tx=0x7f7226468158, stmt=stmt@entry=0x7f72265a7150, space=0x2567ea0, request=<optimized out>) at /usr/src/tarantool/src/box/vinyl.c:6608
#11 0x00000000004615a9 in VinylSpace::executeReplace (this=<optimized out>, txn=<optimized out>, space=<optimized out>, request=<optimized out>) at /usr/src/tarantool/src/box/vinyl_space.cc:108
#12 0x00000000004bd723 in process_rw (request=request@entry=0x7f72265a70f8, space=space@entry=0x2567ea0, result=result@entry=0x7f72264afbc8) at /usr/src/tarantool/src/box/box.cc:182
#13 0x00000000004bed48 in box_process1 (request=0x7f72265a70f8, result=result@entry=0x7f72264afbc8) at /usr/src/tarantool/src/box/box.cc:700
#14 0x00000000004bf389 in box_replace (space_id=space_id@entry=513, tuple=<optimized out>, tuple_end=<optimized out>, result=result@entry=0x7f72264afbc8) at /usr/src/tarantool/src/box/box.cc:754
#15 0x00000000004d72f8 in lbox_replace (L=0x413c5780) at /usr/src/tarantool/src/box/lua/index.c:72
#16 0x000000000050f317 in lj_BC_FUNCC ()
#17 0x00000000004d37c7 in execute_lua_call (L=0x413c5780) at /usr/src/tarantool/src/box/lua/call.c:282
#18 0x000000000050f317 in lj_BC_FUNCC ()
#19 0x0000000000529c7b in lua_cpcall ()
#20 0x00000000004f6aa3 in luaT_cpcall (L=L@entry=0x413c5780, func=func@entry=0x4d36d0 <execute_lua_call>, ud=ud@entry=0x7f72264afde0) at /usr/src/tarantool/src/lua/utils.c:962
#21 0x00000000004d3fe7 in box_process_lua (handler=0x4d36d0 <execute_lua_call>, out=out@entry=0x7f7213020600, request=request@entry=0x413c5780) at /usr/src/tarantool/src/box/lua/call.c:382
#22 box_lua_call (request=request@entry=0x7f72130401d8, out=out@entry=0x7f7213020600) at /usr/src/tarantool/src/box/lua/call.c:405
#23 0x00000000004c0f27 in box_process_call (request=request@entry=0x7f72130401d8, out=out@entry=0x7f7213020600) at /usr/src/tarantool/src/box/box.cc:1074
#24 0x000000000041326c in tx_process_misc (m=0x7f7213040170) at /usr/src/tarantool/src/box/iproto.cc:942
#25 0x0000000000504554 in cmsg_deliver (msg=0x7f7213040170) at /usr/src/tarantool/src/cbus.c:302
#26 0x0000000000504c2e in fiber_pool_f (ap=<error reading variable: value has been optimized out>) at /usr/src/tarantool/src/fiber_pool.c:64
#27 0x000000000041122c in fiber_cxx_invoke(fiber_func, typedef __va_list_tag __va_list_tag *) (f=<optimized out>, ap=<optimized out>) at /usr/src/tarantool/src/fiber.h:645
#28 0x00000000005011a0 in fiber_loop (data=<optimized out>) at /usr/src/tarantool/src/fiber.c:641
#29 0x0000000000688fbf in coro_init () at /usr/src/tarantool/third_party/coro/coro.c:110

Запустите отладчик в цикле, чтобы собрать достаточно информации, которая поможет установить причину спада производительности Tarantool’а. Можно воспользоваться следующим скриптом:

$ rm -f stack-trace.txt
$ watch -n 0.5 "gdb -ex 'set pagination 0' -ex 'thread apply all bt' --batch -p $(pidof tarantool INSTANCENAME.lua) | tee -a stack-trace.txt"

С точки зрения структуры и функциональности, этот скрипт идентичен тому, что используется выше с fiber.info().

Если вам не удается отыскать причину пониженной производительности, запустите данный скрипт на 10-15 секунд и пришлите получившийся файл stack-trace.txt команде Tarantool’а на адрес support@tarantool.org.

Предупреждение

Следует использовать pstack и gdb с осторожностью: каждый раз, подключаясь с работающему процессу, они приостанавливают выполнение этого процесса приблизительно на одну секунду, что может иметь серьезные последствия для высоконагруженных сервисов.

gperftools

Чтобы использовать профилировщик процессора из набора Google Performance Tools с Tarantool’ом, необходимо сначала установить зависимости:

  • Если вы используете Debian/Ubuntu, запустите эту команду:
$ apt-get install libgoogle-perftools4
  • Если вы используете RHEL/CentOS/Fedora, запустите эту команду:
$ yum install gperftools-libs

После этого установите привязки для Lua:

$ tt rocks install gperftools

После окончания установки войдите в интерактивную административную консоль вашего экземпляра Tarantool’а:

$ tt connect NAME|URI

Для запуска профилировщика выполните следующий код:

tarantool> cpuprof = require('gperftools.cpu')
tarantool> cpuprof.start('/home/<имя_пользователя>/tarantool-on-production.prof')

На сбор метрик производительности у профилировщика уходит по крайней мере пара минут. По истечении этого времени можно сохранять информацию на диск (неограниченное количество раз):

tarantool> cpuprof.flush()

Для остановки профилировщика выполните следующую команду:

tarantool> cpuprof.stop()

Теперь можно проанализировать собранные данные с помощью утилиты pprof, которая входит в пакет gperftools:

$ pprof --text /usr/bin/tarantool /home/<имя_пользователя>/tarantool-on-production.prof

Примечание

В дистрибутивах Debian/Ubuntu утилита pprof называется google-pprof.

В консоль должно выводиться приблизительно следующее:

Total: 598 samples
      83 13.9% 13.9% 83 13.9% epoll_wait
      54 9.0% 22.9% 102 17.1%
vy_mem_tree_insert.constprop.35
      32 5.4% 28.3% 34 5.7% __write_nocancel
      28 4.7% 32.9% 42 7.0% vy_mem_iterator_start_from
      26 4.3% 37.3% 26 4.3% _IO_str_seekoff
      21 3.5% 40.8% 21 3.5% tuple_compare_field
      19 3.2% 44.0% 19 3.2%
::TupleCompareWithKey::compare
      19 3.2% 47.2% 38 6.4% tuple_compare_slowpath
      12 2.0% 49.2% 23 3.8% __libc_calloc
       9 1.5% 50.7% 9 1.5%
::TupleCompare::compare@42efc0
       9 1.5% 52.2% 9 1.5% vy_cache_on_write
       9 1.5% 53.7% 57 9.5% vy_merge_iterator_next_key
       8 1.3% 55.0% 8 1.3% __nss_passwd_lookup
       6 1.0% 56.0% 25 4.2% gc_onestep
       6 1.0% 57.0% 6 1.0% lj_tab_next
       5 0.8% 57.9% 5 0.8% lj_alloc_malloc
       5 0.8% 58.7% 131 21.9% vy_prepare

perf

Этот инструмент для мониторинга и анализа производительности устанавливается отдельно с помощью пакетного менеджера. Попробуйте ввести в окне консоли команду perf и следуйте подсказкам, чтобы установить необходимые пакеты.

Примечание

По умолчанию некоторые команды из пакета perf можно выполнять только с root-правами, поэтому необходимо либо зайти в систему из-под пользователя root, либо добавлять перед каждой командой sudo.

Чтобы начать сбор показателей производительности, выполните следующую команду:

$ perf record -g -p $(pidof tarantool INSTANCENAME.lua)

Эта команда сохраняет собранные данные в файл perf.data, который находится в текущей рабочей папке. Для остановки процесса (обычно через 10-15 секунд) нажмите ctrl+C. В консоли должно появиться следующее:

^C[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.225 MB perf.data (1573 samples) ]

Затем выполните эту команду:

$ perf report -n -g --stdio | tee perf-report.txt

Она превращает содержащиеся в perf.data статистические данные в отчет о производительности, который сохраняется в файл perf-report.txt.

Получившийся отчет выглядит следующим образом:

# Samples: 14K of event 'cycles'
# Event count (approx.): 9927346847
#
# Children Self Samples Command Shared Object Symbol
# ........ ........ ............ ......... .................. .......................................
#
    35.50% 0.55% 79 tarantool tarantool [.] lj_gc_step
            |
             --34.95%--lj_gc_step
                       |
                       |--29.26%--gc_onestep
                       | |
                       | |--13.85%--gc_sweep
                       | | |
                       | | |--5.59%--lj_alloc_free
                       | | |
                       | | |--1.33%--lj_tab_free
                       | | | |
                       | | | --1.01%--lj_alloc_free
                       | | |
                       | | --1.17%--lj_cdata_free
                       | |
                       | |--5.41%--gc_finalize
                       | | |
                       | | |--1.06%--lj_obj_equal
                       | | |
                       | | --0.95%--lj_tab_set
                       | |
                       | |--4.97%--rehashtab
                       | | |
                       | | --3.65%--lj_tab_resize
                       | | |
                       | | |--0.74%--lj_tab_set
                       | | |
                       | | --0.72%--lj_tab_newkey
                       | |
                       | |--0.91%--propagatemark
                       | |
                       | --0.67%--lj_cdata_free
                       |
                        --5.43%--propagatemark
                                  |
                                   --0.73%--gc_mark

Инструменты gperftools и perf отличаются от pstack и gdb низкой затратой ресурсов (пренебрежимо малой по сравнению с pstack и gdb): они подключаются к работающим процессам без больших задержек, а потому могут использоваться без серьезных последствий.

jit.p

Профилировщик «jit.p» входит в комплект сервера приложений Tarantool. Чтобы загрузить его, выполните команду require('jit.p') или require('jit.profile'). Есть много параметров для настройки выборки и вывода, они описаны в документации по профилировщику LuaJIT, которая доступна в репозитории LuaJIT на GitHub в ветке 2.1 в файле: doc/ext_profiler.html.

Пример

Создайте функцию для вызова функции под названием f1, которая осуществляет 500 000 вставок и удалений в спейсе Tarantool. Запустите профилировщик, выполните функцию, завершите работу профилировщика. Получите результат выборки профилировщика.

box.space.t:drop()
box.schema.space.create('t')
box.space.t:create_index('i')
function f1() for i = 1,500000 do
  box.space.t:insert{i}
  box.space.t:delete{i}
  end
return 1
end
function f3() f1() end
jit_p = require("jit.profile")
sampletable = {}
jit_p.start("f", function(thread, samples, vmstate)
  local dump=jit_p.dumpstack(thread, "f", 1)
  sampletable[dump] = (sampletable[dump] or 0) + samples
end)
f3()
jit_p.stop()
for d,v in pairs(sampletable) do print(v, d) end

Как правило, результат покажет, что выборка многократно осуществлялась в рамках f1(), а также в рамках внутренних функций Tarantool, имена которых могут изменяться с каждой новой версией.

Контроль за фоновыми программами

Сигналы от сервера

Во время событийного цикла в потоке обработки транзакций Tarantool обрабатывает следующие сигналы:

Сигнал Эффект
SIGHUP Может привести к ротации журналов, см. пример в справочнике по параметрам журналирования Tarantool.
SIGUSR1 Может привести к созданию снимка состояния базы данных, см. описание функции Функция box.snapshot.
SIGTERM Может привести к корректному завершению работы (с предварительным сохранением всех данных).
SIGINT (или «прерывание от клавиатуры») Может привести к корректному завершению работы.
SIGKILL Приводит к аварийному завершению работы.

Остальные сигналы приводят к заданному операционной системой поведению. Все сигналы, за исключением SIGKILL, можно игнорировать, особенно если Tarantool выполняет длительную процедуру и не может вернуться в событийный цикл в потоке обработки транзакций.

Автоматическая перезагрузка экземпляра

На платформах, где доступна утилита systemd, systemd автоматически перезагружает все экземпляры Tarantool при сбое. Чтобы продемонстрировать это, отключим один из экземпляров:

$ systemctl status tarantool@my_app|grep PID
Main PID: 5885 (tarantool)
$ tt connect my_app
   • Connecting to the instance...
   • Connected to /var/run/tarantool/my_app.control
/var/run/tarantool/my_app.control> os.exit(-1)
   ⨯ Connection was closed. Probably instance process isn't running anymore

А теперь убедимся, что systemd перезапустила его:

$ systemctl status tarantool@my_app|grep PID
Main PID: 5914 (tarantool)

Additionally, you can find the information about the instance restart in the boot logs:

$ journalctl -u tarantool@my_app -n 8

Создание дампов памяти

Tarantool создает дамп памяти при получении одного из следующих сигналов: SIGSEGV, SIGFPE, SIGABRT или SIGQUIT. При сбое Tarantool дамп создается автоматически.

На платформах, где доступна утилита systemd, coredumpctl автоматически сохраняет дампы памяти и трассировку стека при аварийном завершении Tarantool-сервера. Вот как включить создание дампов памяти в Unix-системе:

  1. Убедитесь, что лимиты для сессии установлены таким образом, чтобы можно было создавать дампы памяти, – выполните команду ulimit -c unlimited. Также проверьте «man 5 core» на другие причины, по которым дамп памяти может не создаваться.
  2. Создайте директорию для записи дампов памяти и убедитесь, что в эту директорию действительно можно производить запись. На Linux путь до директории задается в параметре ядра, который настраивается через /proc/sys/kernel/core_pattern.
  3. Убедитесь, что дампы памяти включают трассировку стека. При использовании бинарного дистрибутива Tarantool эта информация включается автоматически. При сборке Tarantool из исходников, если передать CMake флаг -DCMAKE_BUILD_TYPE=Release, вы не получите подробной информации.

Для симуляции сбоя можно попытаться выполнить нелегальную команду на работающем экземпляре Tarantool:

$ # !!! please never do this on a production system !!!
$ tt connect my_app
   • Connecting to the instance...
   • Connected to /var/run/tarantool/my_app.control
/var/run/tarantool/my_app.control> require('ffi').cast('char *', 0)[0] = 48
   ⨯ Connection was closed. Probably instance process isn't running anymore

Есть другой способ: если вы знаете PID экземпляра ($PID в нашем примере), можно остановить этот экземпляр, запустив отладчик gdb:

$ gdb -batch -ex "generate-core-file" -p $PID

или послав вручную сигнал SIGABRT:

$ kill -SIGABRT $PID

Примечание

Чтобы узнать PID экземпляра, можно:

  • посмотреть его с помощью box.info.pid,
  • использовать команду ps -A | grep tarantool, или
  • выполнить systemctl status tarantool@my_app|grep PID.

Чтобы посмотреть на последние сбои Tarantool-демона на платформах, где доступна утилита systemd, выполните команду:

$ coredumpctl list /usr/bin/tarantool
MTIME                            PID   UID   GID SIG PRESENT EXE
Sat 2016-01-23 15:21:24 MSK   20681  1000  1000   6   /usr/bin/tarantool
Sat 2016-01-23 15:51:56 MSK   21035   995   992   6   /usr/bin/tarantool

Чтобы сохранить дамп памяти в файл, выполните команду:

$ coredumpctl -o filename.core info <pid>

Трассировка стека

Так как Tarantool хранит кортежи в памяти, файлы с дампами памяти могут быть довольно большими. Чтобы найти проблему, обычно целый файл не нужен – достаточно только «трассировки стека» или «обратной трассировки».

Чтобы сохранить трассировку стека в файл, выполните команду:

$ gdb -se "tarantool" -ex "bt full" -ex "thread apply all bt" --batch -c core> /tmp/tarantool_trace.txt

где:

Примечание

Иногда может оказаться, что файл с трассировкой стека не содержит отладочных символов – в таких строках вместо имени будет стоять ”??”. Если это произошло, ознакомьтесь с инструкциями на этих двух wiki-страницах Tarantool: How to debug core dump of stripped tarantool и How to debug core from different OS.

Чтобы получить трассировку стека и прочую полезную информацию в консоли, выполните команду:

$ coredumpctl info 21035
          PID: 21035 (tarantool)
          UID: 995 (tarantool)
          GID: 992 (tarantool)
       Signal: 6 (ABRT)
    Timestamp: Sat 2016-01-23 15:51:42 MSK (4h 36min ago)
 Command Line: tarantool my_app.lua <running>
   Executable: /usr/bin/tarantool
Control Group: /system.slice/system-tarantool.slice/tarantool@my_app.service
         Unit: tarantool@my_app.service
        Slice: system-tarantool.slice
      Boot ID: 7c686e2ef4dc4e3ea59122757e3067e2
   Machine ID: a4a878729c654c7093dc6693f6a8e5ee
     Hostname: localhost.localdomain
      Message: Process 21035 (tarantool) of user 995 dumped core.

               Stack trace of thread 21035:
               #0  0x00007f84993aa618 raise (libc.so.6)
               #1  0x00007f84993ac21a abort (libc.so.6)
               #2  0x0000560d0a9e9233 _ZL12sig_fatal_cbi (tarantool)
               #3  0x00007f849a211220 __restore_rt (libpthread.so.0)
               #4  0x0000560d0aaa5d9d lj_cconv_ct_ct (tarantool)
               #5  0x0000560d0aaa687f lj_cconv_ct_tv (tarantool)
               #6  0x0000560d0aaabe33 lj_cf_ffi_meta___newindex (tarantool)
               #7  0x0000560d0aaae2f7 lj_BC_FUNCC (tarantool)
               #8  0x0000560d0aa9aabd lua_pcall (tarantool)
               #9  0x0000560d0aa71400 lbox_call (tarantool)
               #10 0x0000560d0aa6ce36 lua_fiber_run_f (tarantool)
               #11 0x0000560d0a9e8d0c _ZL16fiber_cxx_invokePFiP13__va_list_tagES0_ (tarantool)
               #12 0x0000560d0aa7b255 fiber_loop (tarantool)
               #13 0x0000560d0ab38ed1 coro_init (tarantool)
               ...

Отладчик

Для запуска отладчика gdb, выполните команду:

$ coredumpctl gdb <pid>

Мы очень рекомендуем установить пакет tarantool-debuginfo, чтобы сделать отладку средствами gdb более эффективной. Например:

$ dnf debuginfo-install tarantool

С помощью gdb можно узнать, какие еще debuginfo-пакеты нужно установить:

$ gdb -p <pid>
...
Missing separate debuginfos, use: dnf debuginfo-install
glibc-2.22.90-26.fc24.x86_64 krb5-libs-1.14-12.fc24.x86_64
libgcc-5.3.1-3.fc24.x86_64 libgomp-5.3.1-3.fc24.x86_64
libselinux-2.4-6.fc24.x86_64 libstdc++-5.3.1-3.fc24.x86_64
libyaml-0.1.6-7.fc23.x86_64 ncurses-libs-6.0-1.20150810.fc24.x86_64
openssl-libs-1.0.2e-3.fc24.x86_64

В трассировке стека присутствуют символические имена, даже если у вас не установлен пакет tarantool-debuginfo.

Аварийное восстановление

The minimal fault-tolerant Tarantool configuration would be a replica set that includes a master and a replica, or two masters. The basic recommendation is to configure all Tarantool instances in a replica set to create snapshot files on a regular basis.

Here are action plans for typical crash scenarios.

Мастер-реплика

Master crash: manual failover

Configuration: master-replica (manual failover).

Problem: The master has crashed.

Actions:

  1. Ensure the master is stopped. For example, log in to the master machine and use tt stop.
  2. Configure a new replica set leader using the <replicaset_name>.leader option.
  3. Reload configuration on all instances using config:reload().
  4. Make sure that a new replica set leader is a master using box.info.ro.
  5. On a new master, remove a crashed instance from the „_cluster“ space.
  6. Set up a replacement for the crashed master on a spare host.

See also: Performing manual failover.

Master crash: automated failover

Configuration: master-replica (automated failover).

Problem: The master has crashed.

Actions:

  1. Use box.info.election to make sure a new master is elected automatically.
  2. On a new master, remove a crashed instance from the „_cluster“ space.
  3. Set up a replacement for the crashed master on a spare host.

See also: Testing automated failover.

Потеря данных

Configuration: master-replica.

Problem: Some transactions are missing on a replica after the master has crashed.

Actions:

You lose a few transactions in the master write-ahead log file, which may have not transferred to the replica before the crash. If you were able to salvage the master .xlog file, you may be able to recover these.

  1. Посмотрите UUID экземпляра в xlog-файле вышедшего из строя мастера:

    $ head -5 var/lib/instance001/*.xlog | grep Instance
Instance: 9bb111c2-3ff5-36a7-00f4-2b9a573ea660

  2. Используйте этот UUID на новом мастере для поиска позиции:

    app:instance002> box.info.vclock[box.space._cluster.index.uuid:select{'9bb111c2-3ff5-36a7-00f4-2b9a573ea660'}[1][1]]
---
- 999
...

  3. Play the records from the crashed .xlog to the new master, starting from the new master position:

    $ tt play 127.0.0.1:3302 var/lib/instance001/00000000000000000000.xlog \
          --from 1000 \
          --replica 1 \
          --username admin --password secret

Мастер-мастер

Configuration: master-master.

Problem: one master has crashed.

Actions:

  1. Let the load be handled by another master alone.
  2. Remove a crashed master from a replica set.
  3. Set up a replacement for the crashed master on a spare host. Learn more from Adding and removing instances.

Master-replica/master-master: data loss

Configuration: master-replica or master-master.

Problem: Data was deleted at one master and this data loss was propagated to the other node (master or replica).

Actions:

  1. Put all nodes in read-only mode. Depending on the replication.failover mode, this can be done as follows:

    • manual: change a replica set leader to null.
    • election: set replication.election_mode to voter or off at the replica set level.
    • off: set database.mode to ro.

    Reload configurations on all instances using the reload() function provided by the config module.

  2. Turn off deletion of expired checkpoints with box.backup.start(). This prevents the Tarantool garbage collector from removing files made with older checkpoints until box.backup.stop() is called.

  3. Get the latest valid .snap file and use tt cat command to calculate at which LSN the data loss occurred.

  4. Start a new instance and use tt play command to play to it the contents of .snap and .xlog files up to the calculated LSN.

  5. Bootstrap a new replica from the recovered master.

Примечание

The steps above are applicable only to data in the memtx storage engine.

Резервное копирование

Архитектура Tarantool-хранилища позволяет производить обновление только путем присоединения новых записей: сами файлы никогда не перезаписываются. Сборщик мусора Tarantool удаляет старые файлы после определенной контрольной точки. В настройках демона создания контрольных точек можно отложить или запретить работу сборщика мусора. Резервное копирование может проводиться в любое время с минимальной затратой ресурсов.

Для резервного копирования в определенных ситуациях используются две функции:

Горячее резервное копирование (memtx)

Это особый случай, когда все таблицы хранятся в памяти.

Последний созданный Tarantool файл-снимок является резервной копией всей базы данных; а WAL-файлы, созданные следом за последним файлом-снимком, являются инкрементными копиями. Поэтому процедура резервного копирования сводится к копированию последнего файла-снимка и следующих за ним WAL-файлов.

  1. Use tar to make a (possibly compressed) copy of the latest .snap and .xlog files on the snapshot.dir and wal.dir directories.
  2. Если того требуют правила безопасности, зашифруйте получившийся .tar-файл.
  3. Скопируйте .tar-файл в надежное место.

Later, restoring the database is a matter of taking the .tar file and putting its contents back in the snapshot.dir and wal.dir directories.

Горячее резервное копирование (vinyl/memtx)

Vinyl хранит свои файлы в vinyl_dir и создает для каждого спейса в базе данных отдельную поддиректорию. Создание дампов и слияние – это процессы, которые могут лишь добавлять записи, поэтому в результате создаются новые файлы. Сборщик мусора Tarantool может удалять старые файлы после каждой контрольной точки.

Для создания смешанной резервной копии:

  1. Выполните команду box.backup.start() в административной консоли. Эта команда покажет список файлов для резервного копирования и приостановит сборку мусора до следующего вызова box.backup.stop().
  2. Скопируйте файлы из списка в надежное место. Это касается файлов-снимков memtx, выполняемых vinyl-файлов и индексных файлов, соответствующих последней контрольной точке.
  3. Выполните команду box.backup.stop(), чтобы сборщик мусора мог продолжить работу.

Непрерывное удаленное резервное копирование

Репликация обеспечивает резервное копирование и помогает балансировать нагрузку.

Поэтому процесс создания резервной копии сводится к обновлению (при необходимости) одной из реплик с последующим холодным резервным копированием. Так как все остальные реплики продолжают функционировать, с точки зрения конечного пользователя, этот процесс не является холодным резервным копированием. Такое копирование можно выполнять регулярно с помощью планировщика cron или файбера Tarantool.

Непрерывное резервное копирование

По ходу работы системы необходимо сохранять записи об изменениях, внесенных со времени последнего холодного резервного копирования.

Для этого нужна специальная утилита для копирования файлов (например, rsync), которая позволит удаленно и на постоянной основе копировать только изменившиеся части WAL-файла, а не весь файл целиком.

Можно взять и обычную утилиту для копирования целых файлов, но тогда придется создавать файлы-снимки и WAL-файлы на каждое изменение, чтобы нужно было копировать только новые файлы.

Обновление

Важно

This section contains instructions for upgrading Tarantool clusters to versions up to 2.11.x.

This section describes the general upgrade process for Tarantool. There are two main upgrade scenarios for different use cases:

You can also downgrade to an earlier version using a similar procedure.

For information about backwards compatibility, see the compatibility guarantees description.

Upgrading from or to certain versions can involve specific steps or slightly differ from the general upgrade procedure. Such version-specific cases are described on the dedicated pages inside this section.

This section includes the following topics:

Standalone instance upgrade

This page describes the process of upgrading a standalone Tarantool instance in production. Note that this always implies a downtime because the application needs to be stopped and restarted on the target version.

To upgrade without downtime, you need multiple Tarantool servers running in a replication cluster. Find detailed instructions in Replication cluster upgrade.

Checking your application

Before upgrading, make sure your application is compatible with the target Tarantool version:

  1. Set up a development environment with the target Tarantool version installed. See the installation instructions at the Tarantool download page and in the tt install reference.
  2. Deploy the application in this environment and check how it works. In case of any issues, adjust the application code to ensure compatibility with the target version.

When your application is ready to run on the target Tarantool version, you can start upgrading the production environment.

Upgrading a standalone instance

  1. Stop the Tarantool instance.

  2. Make a copy of all data and the package from which the current (old) version was installed. You may need it for rollback purposes. Find the backup instruction in the appropriate hot backup procedure in Backups.

  3. Install the target Tarantool version on the host. You can do this using a package manager or the tt utility. See the installation instructions at Tarantool download page and in the tt install reference. To check that the target Tarantool version is installed, run tarantool -v.

  4. Start your application on the target version.

  5. Run box.schema.upgrade(). This will update the Tarantool system spaces to match the currently installed version of Tarantool.

    Примечание

    To undo schema upgrade in a case of failed upgrade, you can use box.schema.downgrade().

Rollback

The rollback procedure for a standalone instance is almost the same as the upgrade. The only difference is in the last step: you should call box.schema.downgrade() to return the schema to the original version.

Replication cluster upgrade

Below are the general instructions for upgrading a Tarantool cluster with replication. Upgrading from some versions can involve certain specifics. To find out if it is your case, check the version-specific topics of the Upgrades section.

A replication cluster can be upgraded without downtime due to its redundancy. When you disconnect a single instance for an upgrade, there is always another instance that takes over its functionality: being a master storage for the same data buckets or working as a router. This way, you can upgrade all the instances one by one.

The high-level steps of cluster upgrade are the following:

  1. Ensure the application compatibility with the target Tarantool version.
  2. Check the cluster health.
  3. Install the target Tarantool version on the cluster nodes.
  4. Upgrade router nodes one by one.
  5. Upgrade storage replica sets one by one.

Важно

The only way to upgrade Tarantool from version 1.6, 1.7, or 1.9 to 2.x without downtime is to take an intermediate step by upgrading to 1.10 and then to 2.x.

Before upgrading Tarantool from 1.6 to 2.x, please read about the associated caveats.

Примечание

Some upgrade steps are moved to the separate section Procedures and checks to avoid overloading the general instruction with details. Typically, these are checks you should repeat during the upgrade to ensure it goes well.

If you experience issues during upgrade, you can roll back to the original version. The rollback instructions are provided in the Rollback section.

Checking your application

Before upgrading, make sure your application is compatible with the target Tarantool version:

  1. Set up a development environment with the target Tarantool version installed. See the installation instructions at the Tarantool download page and in the tt install reference.
  2. Deploy the application in this environment and check how it works. In case of any issues, adjust the application code to ensure compatibility with the target version.

When your application is ready to run on the target Tarantool version, you can start upgrading the production environment.

Pre-upgrade checks

Perform these steps before the upgrade to ensure that your cluster is working correctly:

  1. On each router instance, perform the vshard.router check:

    tarantool> vshard.router.info()
-- no issues in the output
-- sum of 'bucket.available_rw' == total number of buckets

  2. On each storage instance, perform the replication check:

    tarantool> box.info
-- box.info.status == 'running'
-- box.info.ro == 'false' on one instance in each replica set.
-- box.info.replication[*].upstream.status == 'follow'
-- box.info.replication[*].downstream.status == 'follow'
-- box.info.replication[*].upstream.lag <= box.cfg.replication_timeout
-- can also be moderately larger under a write load

  3. On each storage instance, perform the vshard.storage check:

    tarantool> vshard.storage.info()
-- no issues in the output
-- replication.status == 'follow'

  4. Check all instances“ logs for application errors.

Примечание

If you’re running Cartridge, you can check the health of the cluster instances on the Cluster tab of its web interface.

In case of any issues, make sure to fix them before starting the upgrade procedure.

Installing the target version

Install the target Tarantool version on all hosts of the cluster. You can do this using a package manager or the tt utility. See the installation instructions at the Tarantool download page and in the tt install reference.

Check that the target Tarantool version is installed by running tarantool -v on all hosts.

Upgrading a Tarantool cluster with no downtime

Upgrading routers

Upgrade router instances one by one:

  1. Stop one router instance.
  2. Start this instance on the target Tarantool version.
  3. Repeat the previous steps for each router instance.

After completing the router instances upgrade, perform the vshard.router check on each of them.

Upgrading storages

Before upgrading storage instances:

  • Disable Cartridge failover: run

    tt cartridge failover disable

    or use the Cartridge web interface (Cluster tab, Failover: <Mode> button).

  • Disable the rebalancer: run

    tarantool> vshard.storage.rebalancer_disable()

  • Make sure that the Cartridge upgrade_schema option is false.

Upgrade storage instances by performing the following steps for each replica set:

Примечание

To detect possible upgrade issues early, we recommend that you perform a replication check on all instances of the replica set after each step.

  1. Pick a replica (a read-only instance) from the replica set. Stop this replica and start it again on the target Tarantool version. Wait until it reaches the running status (box.info.status == running).
  2. Restart all other read-only instances of the replica set on the target version one by one.
  3. Make one of the updated replicas the new master using the applicable instruction from Switching the master.
  4. Restart the last instance of the replica set (the former master, now a replica) on the target version.
  1. Run box.schema.upgrade() on the new master. This will update the Tarantool system spaces to match the currently installed version of Tarantool. The changes will be propagated to other nodes via the replication mechanism later.

Предупреждение

This is the point of no return for upgrading from versions earlier than 2.8.2: once you complete it, the schema is no longer compatible with the initial version.

When upgrading from version 2.8.2 or newer, you can undo the schema upgrade using box.schema.downgrade().

  1. Run box.snapshot() on every node in the replica set to make sure that the replicas immediately see the upgraded database state in case of restart.

Once you complete the steps, enable failover or rebalancer back:

  • Enable Cartridge failover: run

    tt cartridge failover set [mode]

    or use the Cartridge web interface (Cluster tab, Failover: Disabled button).

  • Enable the rebalancer: run

    tarantool> vshard.storage.rebalancer_enable()

Post-upgrade checks

Perform these steps after the upgrade to ensure that your cluster is working correctly:

  1. On each router instance, perform the vshard.router check:

    tarantool> vshard.router.info()
-- no issues in the output
-- sum of 'bucket.available_rw' == total number of buckets

  2. On each storage instance, perform the replication check:

    tarantool> box.info
-- box.info.status == 'running'
-- box.info.ro == 'false' on one instance in each replica set.
-- box.info.replication[*].upstream.status == 'follow'
-- box.info.replication[*].downstream.status == 'follow'
-- box.info.replication[*].upstream.lag <= box.cfg.replication_timeout
-- can also be moderately larger under a write load

  3. On each storage instance, perform the vshard.storage check:

    tarantool> vshard.storage.info()
-- no issues in the output
-- replication.status == 'follow'

  4. Check all instances“ logs for application errors.

Примечание

If you’re running Cartridge, you can check the health of the cluster instances on the Cluster tab of its web interface.

Rollback

Rollback before the point of no return

If you decide to roll back before reaching the point of no return, your data is fully compatible with the version you had before the upgrade. In this case, you can roll back the same way: restart the nodes you’ve already upgraded on the original version.

Rollback after the point of no return

If you’ve passed the point of no return (that is, executed box.schema.upgrade()) during the upgrade, then a rollback requires downgrading the schema to the original version.

To check if an automatic downgrade is available for your original version, use box.schema.downgrade_versions(). If the version you need is on the list, execute the following steps on each upgraded replica set to roll back:

  1. Run box.schema.downgrade(<version>) on master specifying the original version.
  2. Run box.snapshot() on every instance in the replica set to make sure that the replicas immediately see the downgraded database state after restart.
  3. Restart all read-only instances of the replica set on the initial version one by one.
  4. Make one of the updated replicas the new master using the applicable instruction from Switching the master.
  5. Restart the last instance of the replica set (the former master, now a replica) on the original version.

Then enable failover or rebalancer back as described in the Upgrading storages.

Recovering from a failed upgrade

Предупреждение

This section applies to cases when the upgrade procedure has failed and the cluster is not functioning properly anymore. Thus, it implies a downtime and a full cluster restart.

In case of an upgrade failure after passing the point of no return, follow these steps to roll back to the original version:

  1. Stop all cluster instances.

  2. Save snapshot and xlog files from all instances whose data was modified after the last backup procedure. These files will help apply these modifications later.

  3. Save the latest backups from all instances.

  4. Restore the original Tarantool version on all hosts of the cluster.

  5. Launch the cluster on the original Tarantool version.

    Примечание

    At this point, the application becomes fully functional and contains data from the backups. However, the data modifications made after the backups were taken must be restored manually.

  6. Manually apply the latest data modifications from xlog files you saved on step 2 using the xlog module. On instances where such changes happened, do the following:

    1. Find out the vclock value of the latest operation in the original WAL.
    2. Play the operations from the newer xlog starting from this vclock on the instance.

    Важно

    If the upgrade has failed after calling box.schema.upgrade(), don’t apply the modifications of system spaces done by this call. This can make the schema incompatible with the original Tarantool version.

Find more information about the Tarantool recovery in Disaster recovery.

Procedures and checks

Replication check

Run box.info:

tarantool> box.info

Check that the following conditions are satisfied:

  • box.info.status is running
  • box.info.replication[*].upstream.status and box.info.replication[*].downstream.status are follow
  • box.info.replication[*].upstream.lag is less or equal than box.cfg.replication_timeout, but it can also be moderately larger under a write load.
  • box.info.ro is false at least on one instance in each replica set. If all instances have box.info.ro = true, this means there are no writable nodes. On Tarantool v. 2.10.0 or later, you can find out why this happened by running box.info.ro_reason. If box.info.ro_reason or box.info.status has the value orphan, the instance doesn’t see the rest of the replica set.

Then run box.info once more and check that box.info.replication[*].upstream.lag values are updated.

vshard.storage check

Run vshard.storage.info():

tarantool> vshard.storage.info()

Check that the following conditions are satisfied:

  • there are no issues or alerts
  • replication.status is follow

vshard.router check

Run vshard.router.info():

tarantool> vshard.router.info()

Check that the following conditions are satisfied:

  • there are no issues or alerts
  • all buckets are available (the sum of bucket.available_rw on all replica sets equals the total number of buckets)

Switching the master

  • Cartridge. If your cluster runs on Cartridge, you can switch the master in the web interface. To do this, go to the Cluster tab, click Edit replica set, and drag an instance to the top of Failover priority list to make it the master.

  • Raft. If your cluster uses automated leader election, switch the master by following these steps:

    1. Pick a candidate – a read-only instance to become the new master.
    2. Run box.ctl.promote() on the candidate. The operation will start and wait for the election to happen.
    3. Run box.cfg{ election_mode = "voter" } on the current master.
    4. Check that the candidate became the new master: its box.info.ro must be false.

  • Legacy. If your cluster neither works on Cartridge nor has automated leader election, switch the master by following these steps:

    1. Pick a candidate – a read-only instance to become the new master.

    2. Run box.cfg{ read_only = true } on the current master.

    3. Check that the candidate’s vclock value matches the master’s: The value of box.info.vclock[<master_id>] on the candidate must be equal to box.info.lsn on the master. <master_id> here is the value of box.info.id on the master.

      If the vclock values don’t match, stop the switch procedure and restore the replica set state by calling box.cfg{ read_only == false } on the master. Then pick another candidate and restart the procedure.

After switching the master, perform the replication check on each instance of the replica set.

Live upgrade from Tarantool 1.6 to 1.10

This page includes explanations and solutions to some common issues when upgrading a replica set from Tarantool 1.6 to 1.10.

Versions later that 1.6 have incompatible .snap and .xlog file formats: 1.6 files are supported during upgrade, but you won’t be able to return to 1.6 after running under 1.10 or 2.x for a while. A few configuration parameters are also renamed.

To perform a live upgrade from Tarantool 1.6 to a more recent version, like 2.8.4, 2.10.1 and such, it is necessary to take an intermediate step by upgrading 1.6 -> 1.10 -> 2.x. This is the only way to perform the upgrade without downtime.

However, a direct upgrade of a replica set from 1.6 to 2.x is also possible, but only with downtime.

The procedure of live upgrade from 1.6 to 1.10 is similar to the general cluster upgrade procedure, but with slight differences in the Upgrading storages step. Find below the general storage upgrade procedure and the 1.6-specific notes for its steps.

General storage upgrade

Upgrade storage instances by performing the following steps for each replica set:

Примечание

To detect possible upgrade issues early, we recommend that you perform a replication check on all instances of the replica set after each step.

  1. Pick a replica (a read-only instance) from the replica set. Stop this replica and start it again on the target Tarantool version. Wait until it reaches the running status (box.info.status == running).
  2. Restart all other read-only instances of the replica set on the target version one by one.
  3. Make one of the updated replicas the new master using the applicable instruction from Switching the master.
  4. Restart the last instance of the replica set (the former master, now a replica) on the target version.
  1. Run box.schema.upgrade() on the new master. This will update the Tarantool system spaces to match the currently installed version of Tarantool. The changes will be propagated to other nodes via the replication mechanism later.
  2. Run box.snapshot() on every node in the replica set to make sure that the replicas immediately see the upgraded database state in case of restart.

1.6 storage upgrade specifics

Upgrade from 1.6 directly to 2.x with downtime

Versions later that 1.6 have incompatible .snap and .xlog file formats: 1.6 files are supported during upgrade, but you won’t be able to return to 1.6 after running under 1.10 or 2.x for a while. A few configuration parameters are also renamed.

To perform a live upgrade from Tarantool 1.6 to a more recent version, like 2.8.4, 2.10.1 and such, it is necessary to take an intermediate step by upgrading 1.6 -> 1.10 -> 2.x. This is the only way to perform the upgrade without downtime.

However, a direct upgrade of a replica set from 1.6 to 2.x is also possible, but only with downtime.

Here is how to upgrade from Tarantool 1.6 directly to 2.x:

  1. Stop all instances in the replica set.
  2. Upgrade Tarantool version to 2.x on every instance.
  3. Upgrade the corresponding instance files and applications, if needed.
  4. Start all the instances with Tarantool 2.x.
  5. Execute box.schema.upgrade() on the master.
  6. Execute box.snapshot() on every node in the replica set.

Fix decimal values in vinyl spaces when upgrading to 2.10.1

This is an upgrade guide for fixing one specific problem which could happen with decimal values in vinyl spaces. It’s only relevant when you’re upgrading from Tarantool version <= 2.10.0 to anything >= 2.10.1.

Before gh-6377 was fixed, decimal and double values in a scalar or number index could end up in the wrong order after the update. If such an index has been built for a space that uses the vinyl storage engine, the index is persisted and is not rebuilt even after the upgrade. If this is the case, the user has to rebuild the affected indexes manually.

Here are the rules to determine whether your installation was affected. If all of the statements listed below are true, you have to rebuild indexes for the affected vinyl spaces manually.

If this is the case for you, you can run the following script, which will find all the affected indices:

local fiber = require('fiber')
local decimal = require('decimal')

local function isnan(val)
    return type(val) == 'number' and val ~= val
end

local function isinf(val)
    return val == math.huge or val == -math.huge
end

local function vinyl(id)
    return box.space[id].engine == 'vinyl'
end

require_rebuild = {}
local iters = 0
for _, v in box.space._index:pairs({512, 0}, {iterator='GE'}) do
    local id = v[1]
    iters = iters + 1
    if iters % 1000 == 0 then
        fiber.yield()
    end
    if vinyl(id) then
        local format = v[6]
        local check_fields = {}
        for _, fmt in pairs(v[6]) do
            if fmt[2] == 'number' or fmt[2] == 'scalar' then
                table.insert(check_fields,  fmt[1] + 1)
            end
        end
        local have_decimal = {}
        local have_nan = {}
        if #check_fields > 0 then
            for k, tuple in box.space[id]:pairs() do
                for _, i in pairs(check_fields) do
                    iters = iters + 1
                    if iters % 1000 == 0 then
                        fiber.yield()
                    end
                    have_decimal[i] = have_decimal[i] or
                                    decimal.is_decimal(tuple[i])
                    have_nan[i] = have_nan[i] or isnan(tuple[i]) or
                                isinf(tuple[i])
                    if have_decimal[i] and have_nan[i] then
                        table.insert(require_rebuild, v)
                        goto out
                    end
                end
            end
        end
    end
    ::out::
end

The indices requiring a rebuild will be stored in the require_rebuild table. If the table is empty, you’re safe and can continue using Tarantool as before.

If the require_rebuild table contains some entries, you can rebuild the affected indices with the following script.

Примечание

Please run the script below only on the master node and only after all the nodes are upgraded to the new Tarantool version.

local log = require('log')

local function rebuild_index(idx)
    local index_name = idx[3]
    local space_name = box.space[idx[1]].name
    log.info("Rebuilding index %s on space %s", index_name, space_name)
    if (idx[2] == 0) then
        log.error("Cannot rebuild primary index %s on space %s. Please, "..
                "recreate the space manually", index_name, space_name)
        return
    end
    log.info("Deleting index %s on space %s", index_name, space_name)
    local v = box.space._index:delete{idx[1], idx[2]}
    if v == nil then
        log.error("Couldn't find index %s on space %s", index_name, space_name)
        return
    end
    log.info("Done")
    log.info("Creating index %s on space %s", index_name, space_name)
    box.space._index:insert(v)
end

for _, idx in pairs(require_rebuild) do
    rebuild_index(idx)
end

The script might fail on some of the indices with the following error: «Cannot rebuild primary index index_name on space space_name. Please, recreate the space manually». If this happens, automatic index rebuild is impossible, and you have to manually re-create the space to ensure data integrity:

  1. Create a new space with the same format as the existing one.
  2. Define the same indices on the freshly created space.
  3. Iterate over the old space’s primary key and insert all the data into the new space.
  4. Drop the old space.

Fix illegal type names when upgrading to 2.10.4

This is an upgrade guide for fixing one specific problem which could happen with field type names. It’s only relevant when you’re upgrading from a Tarantool version <=2.10.3 to >=2.10.4.

Before gh-5940 was fixed, the empty string, n, nu, s, and st (that is, leading parts of num and str) were accepted as valid field types. Since 2.10.4, Tarantool doesn’t accept these strings and they must be replaced with correct values num and str.

This instruction is also available on GitHub.

Check if your snapshots contain illegal type names

A snapshot can be validated against the issue using the following script:

#!/usr/bin/env tarantool

local xlog = require('xlog')
local json = require('json')

if arg[1] == nil then
    print(('Usage: %s xxxxxxxxxxxxxxxxxxxx.snap'):format(arg[0]))
    os.exit(1)
end

local illegal_types = {
    [''] = true,
    ['n'] = true,
    ['nu'] = true,
    ['s'] = true,
    ['st'] = true,
}

local function report_field_def(name, field_def)
    local msg = 'A field def in a _space entry %q contains an illegal type: %s'
    print(msg:format(name, json.encode(field_def)))
end

local has_broken_format = false

for _, record in xlog.pairs(arg[1]) do
    -- Filter inserts.
    if record.HEADER == nil or record.HEADER.type ~= 'INSERT' then
        goto continue
    end
    -- Filter _space records.
    if record.BODY == nil or record.BODY.space_id ~= 280 then
        goto continue
    end

    local tuple = record.BODY.tuple
    local name = tuple[3]
    local format = tuple[7]

    local is_format_broken = false
    for _, field_def in ipairs(format) do
        if illegal_types[field_def.type] ~= nil then
            report_field_def(name, field_def)
            is_format_broken = true
        end

        if illegal_types[field_def[2]] ~= nil then
            report_field_def(name, field_def)
            is_format_broken = true
        end

    end

    if is_format_broken then
        has_broken_format = true
        local msg = 'The following _space entry contains illegal type(s): %s'
        print(msg:format(json.encode(record)))
    end
    ::continue::
end

if has_broken_format then
    print('')
    print(('%s has an illegal type in a space format'):format(arg[1]))
    print('It is recommended to proceed with the upgrade instruction:')
    print('https://github.com/tarantool/tarantool/wiki/Fix-illegal-field-type-in-a-space-format-when-upgrading-to-2.10.4')
else
    print('Everything looks nice!')
end

os.exit(has_broken_format and 2 or 0)

If the snapshot contains the values that aren’t valid in 2.10.4, you’ll get an output like the following:

Fix an application file

To fix the application file that contains illegal type names, add the following code in it before the box.cfg()/vshard.cfg()/cartridge.cfg() call.

Примечание

In Cartridge applications, the instance file is called init.lua.

-- Convert illegal type names in a space format that were
-- allowed before tarantool 2.10.4.

local log = require('log')
local json = require('json')

local transforms = {
    [''] = 'num',
    ['n'] = 'num',
    ['nu'] = 'num',
    ['s'] = 'str',
    ['st'] = 'str',
}

-- The helper for before_replace().
local function transform_field_def(name, field_def, field, new_type)
    local field_def_old_str = json.encode(field_def)
    field_def[field] = new_type
    local field_def_new_str = json.encode(field_def)

    local msg = 'Transform a field def in a _space entry %q: %s -> %s'
    log.info(msg:format(name, field_def_old_str, field_def_new_str))
end

-- _space trigger.
local function before_replace(_, tuple)
    if tuple == nil then return tuple end

    local name = tuple[3]
    local format = tuple[7]

    -- Update format if necessary.
    local is_format_changed = false
    for i, field_def in ipairs(format) do
        local new_type = transforms[field_def.type]
        if new_type ~= nil then
            transform_field_def(name, field_def, 'type', new_type)
            is_format_changed = true
        end

        local new_type = transforms[field_def[2]]
        if new_type ~= nil then
            transform_field_def(name, field_def, 2, new_type)
            is_format_changed = true
        end
    end

    -- No changed: skip.
    if not is_format_changed then return tuple end

    -- Rebuild the tuple.
    local new_tuple = tuple:transform(7, 1, format)
    log.info(('Transformed _space entry %s to %s'):format(
        json.encode(tuple), json.encode(new_tuple)))
    return new_tuple
end

-- on_schema_init trigger to set before_replace().
local function on_schema_init()
    box.space._space:before_replace(before_replace)
end

-- Set the trigger on _space.
box.ctl.on_schema_init(on_schema_init)

You can delete these triggers after the box.cfg()/vshard.cfg()/cartridge.cfg() call.

An example for a Cartridge application:

The triggers will report the changes the make in the following form:

Recover from WALs with mixed transactions when upgrading to 2.11.0

This is a guide on fixing a specific problem that could happen when upgrading from a Tarantool version between 2.1.2 and 2.2.0 to 2.8.1 or later. The described solution is applicable since version 2.11.0.

The problem is described in the issue gh-7932. If two or more transactions happened simultaneously in Tarantool 2.1.2-2.2.0, their operations could be written to the write-ahead log mixed with each other. Starting from version 2.8.1, Tarantool recovers transactions atomically and expects all WAL entries between a transaction’s begin and commit operations to belong to one transaction. If there is an operation belonging to another transaction, Tarantool fails to recover from such a WAL.

Starting from version 2.11.0, Tarantool can recover from WALs with mixed transactions in the force_recovery mode.

Instances fail to start

If all instances or some of them fail to start after upgrading to 2.11 or a newer version due to a recovery error:

  1. Start these instances with the force_recovery option to true.
  2. Make new snapshots on the instances so that the old WALs with mixed transactions aren’t used for recovery anymore. To do this, call box.snapshot().
  3. Set force_recovery back to false.

Replication doesn’t work

After all the instances start successfully, WALs with mixed transactions may still lead to replication issues. Some instances may fail to replicate from other instances because they are sending incorrect WALs. To fix the replication issues, rebootstrap the instances that fail to replicate.

Сообщения об ошибках

Если вы нашли ошибку в Tarantool, вы окажете нам услугу, сообщив о ней.

Пожалуйста, откройте тикет в репозитории Tarantool на GitHub. Рекомендуем включить следующую информацию:

Если это запрос новой функции или это затрагивает определенную группу пользователей, не забудьте это указать.

Обычно член команды Tarantool отвечает в течение одного-двух рабочих дней, чтобы подтвердить, что тикет взят в работу, задать уточняющие вопросы или предложить альтернативное решение описанной проблемы.

Flight recorder

Enterprise Edition

The flight recorder is available in the Enterprise Edition only.

Example on GitHub: flightrec

The flight recorder is an event collection tool that gathers various information about a working Tarantool instance, such as:

This information helps you investigate incidents related to crashing a Tarantool instance.

Enable the flight recorder

The flight recorder is disabled by default and can be enabled and configured for a specific Tarantool instance. To enable the flight recorder, set the flightrec.enabled configuration option to true.

flightrec:
  enabled: true

After flightrec.enabled is set to true, the flight recorder starts collecting data in the flight recording file current.ttfr. This file is stored in the snapshot.dir directory. By default, the directory is var/lib/{{ instance_name }}/<file_name>.ttfr.

If the instance crashes and reboots, Tarantool rotates the flight recording: current.ttfr is renamed to <timestamp>.ttfr (for example, 20230411T050721.ttfr) and the new current.ttfr file is created for collecting data. In the case of correct shutdown (for example, using os.exit()), Tarantool continues writing to the existing current.ttfr file after restart.

Примечание

Note that old flight recordings should be removed manually.

Configure the flight recorder

When the flight recorder is enabled, you can set the options related to logging, metrics, and storing the request and response data.

The flightrec configuration might look as follows:

flightrec:
  enabled: true
  logs_size: 10485800
  logs_log_level: 5
  metrics_period: 240
  metrics_interval: 0.5
  requests_size: 10485780

In the example, the following options are set:

Read more: Flight recorder configuration options.

Monitoring

Monitoring is the process of capturing runtime information about the instances of a Tarantool cluster using metrics. Metrics can indicate various characteristics, such as memory usage, the number of records in spaces, replication status, and so on. Typically, metrics are monitored in real time, allowing for the identification of current issues or the prediction of potential ones.

Getting started with monitoring

Example on GitHub: sharded_cluster_crud_metrics

Tarantool allows you to configure and expose its metrics using a YAML configuration. You can also use the built-in metrics module to create and collect custom metrics.

Configuring metrics

To configure metrics, use the metrics section in a cluster configuration. The configuration below enables all metrics excluding vinyl-specific ones:

metrics:
  include: [ all ]
  exclude: [ vinyl ]
  labels:
    alias: '{{ instance_name }}'

The metrics.labels option accepts the predefined {{ instance_name }} variable. This adds an instance name as a label to every observation.

Third-party Lua modules, like crud or expirationd, offer their own metrics. You can enable these metrics by configuring the corresponding role. The example below shows how to enable statistics on called operations by providing the roles.crud-router role’s configuration:

roles:
- roles.crud-router
- roles.metrics-export
roles_cfg:
  roles.crud-router:
    stats: true
    stats_driver: metrics
    stats_quantiles: true

expirationd metrics can be enabled as follows:

expirationd:
  cfg:
    metrics: true

Exposing metrics

To expose metrics in different formats, you can use a third-party metrics-export-role role. In the following example, the metrics of storage-a-001 are provided on two endpoints:

storage-a-001:
  roles_cfg:
    roles.metrics-export:
      http:
      - listen: '127.0.0.1:8082'
        endpoints:
        - path: /metrics/prometheus/
          format: prometheus
        - path: /metrics/json
          format: json

Example on GitHub: sharded_cluster_crud_metrics

Примечание

The metrics module provides a set of plugins that can be used to collect and expose metrics in different formats. Learn more in Collecting metrics using plugins.

Creating custom metrics

The metrics module allows you to create and collect custom metrics. The example below shows how to collect the number of data operations performed on the specified space by increasing a counter value inside the on_replace() trigger function:

local metrics = require('metrics')
local bands_replace_count = metrics.counter('bands_replace_count', 'The number of data operations')
local trigger = require('trigger')
trigger.set(
        'box.space.bands.on_replace',
        'update_bands_replace_count_metric',
        function(_, _, _, request_type)
            bands_replace_count:inc(1, { request_type = request_type })
        end
)

Learn more in Custom metrics.

Collecting metrics

When metrics are configured and exposed, you can use the desired third-party tool to collect them. Below is the example of a Prometheus scrape configuration that collects metrics of multiple Tarantool instances:

global:
  scrape_interval:     5s
  evaluation_interval: 5s

scrape_configs:
  - job_name: prometheus
    static_configs:
      - targets:
          - 127.0.0.1:8081
          - 127.0.0.1:8082
          - 127.0.0.1:8083
          - 127.0.0.1:8084
          - 127.0.0.1:8085
    metrics_path: "/metrics/prometheus"

For more information on collecting and visualizing metrics, refer to Grafana dashboard.

Примечание

Tarantool Cluster Manager allows you to view metrics of connected clusters in real time. Learn more in Viewing cluster metrics.

Grafana dashboard

After enabling and configuring metrics, you can visualise them using Tarantool Grafana dashboards. These dashboards are available as part of Grafana official & community-built dashboards:

Tarantool 3 Prometheus, InfluxDB
Tarantool Cartridge and Tarantool 1.10—2.x Prometheus, InfluxDB
Tarantool Data Grid 2 Prometheus, InfluxDB

The Tarantool Grafana dashboard is a ready for import template with basic memory, space operations, and HTTP load panels, based on default metrics package functionality.

../../../_images/Prometheus_dashboard_1.png ../../../_images/Prometheus_dashboard_2.png ../../../_images/Prometheus_dashboard_3.png

Prepare a monitoring stack

Since there are Prometheus and InfluxDB data source Grafana dashboards, you can use one of the following:

For issues related to setting up Prometheus, Telegraf, InfluxDB, or Grafana instances, refer to the corresponding project’s documentation.

Collect metrics with server agents

Prometheus

To collect metrics for Prometheus, first set up metrics output with prometheus format. You can use the roles.metrics-export configuration or set up the Prometheus plugin manually. To start collecting metrics, add a job to Prometheus configuration with each Tarantool instance URI as a target and metrics path as it was configured on Tarantool instances:

global:
  scrape_interval:     5s
  evaluation_interval: 5s

scrape_configs:
  - job_name: prometheus
    static_configs:
      - targets:
          - 127.0.0.1:8081
          - 127.0.0.1:8082
          - 127.0.0.1:8083
          - 127.0.0.1:8084
          - 127.0.0.1:8085
    metrics_path: "/metrics/prometheus"

InfluxDB

To collect metrics for InfluxDB, use the Telegraf agent. First off, configure Tarantool metrics output in json format with roles.metrics-export configuration or corresponding JSON plugin. To start collecting metrics, add http input to Telegraf configuration including each Tarantool instance metrics URL:

[[inputs.http]]
    urls = [
        "http://example_project:8081/metrics/json",
        "http://example_project:8082/metrics/json",
        "http://example_project:8083/metrics/json",
        "http://example_project:8084/metrics/json",
        "http://example_project:8085/metrics/json"
    ]
    timeout = "30s"
    tag_keys = [
        "metric_name",
        "label_pairs_alias",
        "label_pairs_quantile",
        "label_pairs_path",
        "label_pairs_method",
        "label_pairs_status",
        "label_pairs_operation",
        "label_pairs_level",
        "label_pairs_id",
        "label_pairs_engine",
        "label_pairs_name",
        "label_pairs_index_name",
        "label_pairs_delta",
        "label_pairs_stream",
        "label_pairs_thread",
        "label_pairs_kind"
    ]
    insecure_skip_verify = true
    interval = "10s"
    data_format = "json"
    name_prefix = "tarantool_"
    fieldpass = ["value"]

Be sure to include each label key as label_pairs_<key> to extract it with the plugin. For example, if you use { state = 'ready' } labels somewhere in metric collectors, add label_pairs_state tag key.

Import the dashboard

Open Grafana import menu.

../../../_images/grafana_import.png

To import a specific dashboard, choose one of the following options:

Set dashboard name, folder and uid (if needed).

../../../_images/grafana_import_setup.png

You can choose the data source and data source variables after import.

../../../_images/grafana_variables_setup.png

Troubleshooting

Alerting

You can set up alerts on metrics to get a notification when something went wrong. We will use Prometheus alert rules as an example here. You can get full alerts.yml file at tarantool/grafana-dashboard GitHub repo.

Tarantool metrics

You can use internal Tarantool metrics to monitor detailed RAM consumption, replication state, database engine status, track business logic issues (like HTTP 4xx and 5xx responses or low request rate) and external modules statistics (like CRUD errors). Evaluation timeouts, severity levels and thresholds (especially ones for business logic) are placed here for the sake of example: you may want to increase or decrease them for your application. Also, don’t forget to set sane rate time ranges based on your Prometheus configuration.

Lua memory

Monitoring tnt_info_memory_lua metric may prevent memory overflow and detect the presence of bad Lua code practices.

Примечание

The Lua memory is limited to 2 GB per instance if Tarantool doesn’t have the GC64 mode enabled for LuaJIT.

- alert: HighLuaMemoryWarning
  expr: tnt_info_memory_lua >= (512 * 1024 * 1024)
  for: 1m
  labels:
    severity: warning
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') Lua runtime warning"
    description: "'{{ $labels.alias }}' instance of job '{{ $labels.job }}' uses too much Lua memory
      and may hit threshold soon."

- alert: HighLuaMemoryAlert
  expr: tnt_info_memory_lua >= (1024 * 1024 * 1024)
  for: 1m
  labels:
    severity: page
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') Lua runtime alert"
    description: "'{{ $labels.alias }}' instance of job '{{ $labels.job }}' uses too much Lua memory
      and likely to hit threshold soon."

Memtx arena memory

By monitoring slab allocation statistics you can see how many free RAM is remaining to store memtx tuples and indexes for an instance. If Tarantool hit the limits, the instance will become unavailable for write operations, so this alert may help you see when it’s time to increase your memtx_memory limit or to add a new storage to a vshard cluster.

- alert: LowMemtxArenaRemainingWarning
  expr: (tnt_slab_quota_used_ratio >= 80) and (tnt_slab_arena_used_ratio >= 80)
  for: 1m
  labels:
    severity: warning
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') low arena memory remaining"
    description: "Low arena memory (tuples and indexes) remaining for '{{ $labels.alias }}' instance of job '{{ $labels.job }}'.
      Consider increasing memtx_memory or number of storages in case of sharded data."

- alert: LowMemtxArenaRemaining
  expr: (tnt_slab_quota_used_ratio >= 90) and (tnt_slab_arena_used_ratio >= 90)
  for: 1m
  labels:
    severity: page
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') low arena memory remaining"
    description: "Low arena memory (tuples and indexes) remaining for '{{ $labels.alias }}' instance of job '{{ $labels.job }}'.
      You are likely to hit limit soon.
      It is strongly recommended to increase memtx_memory or number of storages in case of sharded data."

- alert: LowMemtxItemsRemainingWarning
  expr: (tnt_slab_quota_used_ratio >= 80) and (tnt_slab_items_used_ratio >= 80)
  for: 1m
  labels:
    severity: warning
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') low items memory remaining"
    description: "Low items memory (tuples) remaining for '{{ $labels.alias }}' instance of job '{{ $labels.job }}'.
      Consider increasing memtx_memory or number of storages in case of sharded data."

- alert: LowMemtxItemsRemaining
  expr: (tnt_slab_quota_used_ratio >= 90) and (tnt_slab_items_used_ratio >= 90)
  for: 1m
  labels:
    severity: page
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') low items memory remaining"
    description: "Low items memory (tuples) remaining for '{{ $labels.alias }}' instance of job '{{ $labels.job }}'.
      You are likely to hit limit soon.
      It is strongly recommended to increase memtx_memory or number of storages in case of sharded data."

Vinyl engine status

You can monitor vinyl regulator performance to track possible scheduler or disk issues.

- alert: LowVinylRegulatorRateLimit
  expr: tnt_vinyl_regulator_rate_limit < 100000
  for: 1m
  labels:
    severity: warning
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') have low vinyl regulator rate limit"
    description: "Instance '{{ $labels.alias }}' of job '{{ $labels.job }}' have low vinyl engine regulator rate limit.
      This indicates issues with the disk or the scheduler."

Vinyl transactions errors are likely to lead to user requests errors.

- alert: HighVinylTxConflictRate
  expr: rate(tnt_vinyl_tx_conflict[5m]) / rate(tnt_vinyl_tx_commit[5m]) > 0.05
  for: 1m
  labels:
    severity: critical
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') have high vinyl tx conflict rate"
    description: "Instance '{{ $labels.alias }}' of job '{{ $labels.job }}' have
      high vinyl transactions conflict rate. It indicates that vinyl is not healthy."

Vinyl scheduler failed tasks are a good signal of disk issues and may be the reason of increasing RAM consumption.

- alert: HighVinylSchedulerFailedTasksRate
  expr: rate(tnt_vinyl_scheduler_tasks{status="failed"}[5m]) > 0.1
  for: 1m
  labels:
    severity: critical
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') have high vinyl scheduler failed tasks rate"
    description: "Instance '{{ $labels.alias }}' of job '{{ $labels.job }}' have
      high vinyl scheduler failed tasks rate."

Replication state

If tnt_replication_status is equal to 0, instance replication status is not equal to "follows": replication is either not ready yet or has been stopped due to some reason.

- alert: ReplicationNotRunning
  expr: tnt_replication_status == 0
  for: 1m
  labels:
    severity: critical
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') {{ $labels.stream }} (id {{ $labels.id }})
      replication is not running"
    description: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') {{ $labels.stream }} (id {{ $labels.id }})
      replication is not running."

Even if async replication is "follows", it could be considered malfunctioning if the lag is too high. It also may affect Tarantool garbage collector work, see box.info.gc().

- alert: HighReplicationLag
  expr: tnt_replication_lag > 1
  for: 1m
  labels:
    severity: warning
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') have high replication lag (id {{ $labels.id }})"
    description: "Instance '{{ $labels.alias }}' of job '{{ $labels.job }}' have high replication lag
      (id {{ $labels.id }}), check up your network and cluster state."

Event loop

High fiber event loop time leads to bad application performance, timeouts and various warnings. The reason could be a high quantity of working fibers or fibers that spend too much time without any yields or sleeps.

- alert: HighEVLoopTime
  expr: tnt_ev_loop_time > 0.1
  for: 1m
  labels:
    severity: warning
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') event loop has high cycle duration"
    description: "Instance '{{ $labels.alias }}' of job '{{ $labels.job }}' event loop has high cycle duration.
      Some high loaded fiber has too little yields. It may be the reason of 'Too long WAL write' warnings."

Configuration status

Configuration status displays Tarantool 3 configuration apply state. Additional metrics display the count of apply warnings and errors.

- alert: ConfigWarningAlerts
  expr: tnt_config_alerts{level="warn"} > 0
  for: 1m
  labels:
    severity: warning
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') has configuration 'warn' alerts"
    description: "Instance '{{ $labels.alias }}' of job '{{ $labels.job }}' has configuration 'warn' alerts.
                  Please, check config:info() for detailed info."

- alert: ConfigErrorAlerts
  expr: tnt_config_alerts{level="error"} > 0
  for: 1m
  labels:
    severity: page
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') has configuration 'error' alerts"
    description: "Instance '{{ $labels.alias }}' of job '{{ $labels.job }}' has configuration 'error' alerts.
                  Latest configuration has not been applied.
                  Please, check config:info() for detailed info."

- alert: ConfigStatusNotReady
  expr: tnt_config_status{status="ready"} == 0
  for: 5m
  labels:
    severity: warning
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') configuration is not ready"
    description: "Instance '{{ $labels.alias }}' of job '{{ $labels.job }}' configuration is not ready.
                  Please, check config:info() for detailed info."

HTTP server statistics

metrics allows to monitor tarantool/http handles, see «Collecting HTTP request latency statistics». Here we use a summary collector with a default name and 0.99 quantile computation.

Too many responses with error codes usually is a sign of API issues or application malfunction.

- alert: HighInstanceHTTPClientErrorRate
  expr: sum by (job, instance, method, path, alias) (rate(http_server_request_latency_count{ job="tarantool", status=~"^4\\d{2}$" }[5m])) > 10
  for: 1m
  labels:
    severity: page
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') high rate of client error responses"
    description: "Too many {{ $labels.method }} requests to {{ $labels.path }} path
      on '{{ $labels.alias }}' instance of job '{{ $labels.job }}' get client error (4xx) responses."

- alert: HighHTTPClientErrorRate
  expr: sum by (job, method, path) (rate(http_server_request_latency_count{ job="tarantool", status=~"^4\\d{2}$" }[5m])) > 20
  for: 1m
  labels:
    severity: page
  annotations:
    summary: "Job '{{ $labels.job }}' high rate of client error responses"
    description: "Too many {{ $labels.method }} requests to {{ $labels.path }} path
      on instances of job '{{ $labels.job }}' get client error (4xx) responses."

- alert: HighHTTPServerErrorRate
  expr: sum by (job, instance, method, path, alias) (rate(http_server_request_latency_count{ job="tarantool", status=~"^5\\d{2}$" }[5m])) > 0
  for: 1m
  labels:
    severity: page
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') server error responses"
    description: "Some {{ $labels.method }} requests to {{ $labels.path }} path
      on '{{ $labels.alias }}' instance of job '{{ $labels.job }}' get server error (5xx) responses."

Responding with high latency is a synonym of insufficient performance. It may be a sign of application malfunction. Or maybe you need to add more routers to your cluster.

- alert: HighHTTPLatency
  expr: http_server_request_latency{ job="tarantool", quantile="0.99" } > 0.1
  for: 5m
  labels:
    severity: warning
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') high HTTP latency"
    description: "Some {{ $labels.method }} requests to {{ $labels.path }} path with {{ $labels.status }} response status
      on '{{ $labels.alias }}' instance of job '{{ $labels.job }}' are processed too long."

Having too little requests when you expect them may detect balancer, external client or network malfunction.

- alert: LowRouterHTTPRequestRate
  expr: sum by (job, instance, alias) (rate(http_server_request_latency_count{ job="tarantool", alias=~"^.*router.*$" }[5m])) < 10
  for: 5m
  labels:
    severity: warning
  annotations:
    summary: "Router '{{ $labels.alias }}' ('{{ $labels.job }}') low activity"
    description: "Router '{{ $labels.alias }}' instance of job '{{ $labels.job }}' gets too little requests.
      Please, check up your balancer middleware."

CRUD module statistics

If your application uses CRUD module requests, monitoring module statistics may track internal errors caused by invalid process of input and internal parameters.

- alert: HighCRUDErrorRate
  expr: rate(tnt_crud_stats_count{ job="tarantool", status="error" }[5m]) > 0.1
  for: 1m
  labels:
    severity: critical
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') too many CRUD {{ $labels.operation }} errors."
    description: "Too many {{ $labels.operation }} CRUD requests for '{{ $labels.name }}' space on
      '{{ $labels.alias }}' instance of job '{{ $labels.job }}' get module error responses."

Statistics could also monitor requests performance. Too high request latency will lead to high latency of client responses. It may be caused by network or disk issues. Read requests with bad (with respect to space indexes and sharding schema) conditions may lead to full-scans or map reduces and also could be the reason of high latency.

- alert: HighCRUDLatency
  expr: tnt_crud_stats{ job="tarantool", quantile="0.99" } > 0.1
  for: 1m
  labels:
    severity: warning
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') too high CRUD {{ $labels.operation }} latency."
    description: "Some {{ $labels.operation }} {{ $labels.status }} CRUD requests for '{{ $labels.name }}' space on
      '{{ $labels.alias }}' instance of job '{{ $labels.job }}' are processed too long."

You also can directly monitor map reduces and scan rate.

- alert: HighCRUDMapReduceRate
  expr: rate(tnt_crud_map_reduces{ job="tarantool" }[5m]) > 0.1
  for: 1m
  labels:
    severity: warning
  annotations:
    summary: "Instance '{{ $labels.alias }}' ('{{ $labels.job }}') too many CRUD {{ $labels.operation }} map reduces."
    description: "There are too many {{ $labels.operation }} CRUD map reduce requests for '{{ $labels.name }}' space on
      '{{ $labels.alias }}' instance of job '{{ $labels.job }}'.
      Check your request conditions or consider changing sharding schema."

Server-side monitoring

If there are no Tarantool metrics, you may miss critical conditions. Prometheus provide up metric to monitor the health of its targets.

- alert: InstanceDown
  expr: up == 0
  for: 1m
  labels:
    severity: page
  annotations:
    summary: "Instance '{{ $labels.instance }}' ('{{ $labels.job }}') down"
    description: "'{{ $labels.instance }}' of job '{{ $labels.job }}' has been down for more than a minute."

Do not forget to monitor your server’s CPU, disk and RAM from server side with your favorite tools. For example, on some high CPU consumption cases Tarantool instance may stop to send metrics, so you can track such breakdowns only from the outside.

Metrics reference

This page provides a detailed description of metrics from the metrics module.

General metrics

General instance information:

tnt_cfg_current_time Instance system time in the Unix timestamp format
tnt_info_uptime Time in seconds since the instance has started
tnt_read_only Indicates if the instance is in read-only mode (1 if true, 0 if false)

Memory general

The following metrics provide a picture of memory usage by the Tarantool process.

tnt_info_memory_cache Number of bytes in the cache used to store tuples with the vinyl storage engine.
tnt_info_memory_data Number of bytes used to store user data (tuples) with the memtx engine and with level 0 of the vinyl engine, without regard for memory fragmentation.
tnt_info_memory_index Number of bytes used for indexing user data. Includes memtx and vinyl memory tree extents, the vinyl page index, and the vinyl bloom filters.
tnt_info_memory_lua Number of bytes used for the Lua runtime. Monitoring this metric can prevent memory overflow.
tnt_info_memory_net Number of bytes used for network input/output buffers.
tnt_info_memory_tx Number of bytes in use by active transactions. For the vinyl storage engine, this is the total size of all allocated objects (struct txv, struct vy_tx, struct vy_read_interval) and tuples pinned for those objects.

Memory allocation

Provides a memory usage report for the slab allocator. The slab allocator is the main allocator used to store tuples. The following metrics help monitor the total memory usage and memory fragmentation. To learn more about use cases, refer to the box.slab submodule documentation.

Available memory, bytes:

tnt_slab_quota_size Amount of memory available to store tuples and indexes. Is equal to memtx_memory.
tnt_slab_arena_size Total memory available to store both tuples and indexes. Includes allocated but currently free slabs.
tnt_slab_items_size Total amount of memory available to store only tuples and not indexes. Includes allocated but currently free slabs.

Memory usage, bytes:

tnt_slab_quota_used The amount of memory that is already reserved by the slab allocator.
tnt_slab_arena_used The effective memory used to store both tuples and indexes. Disregards allocated but currently free slabs.
tnt_slab_items_used The effective memory used to store only tuples and not indexes. Disregards allocated but currently free slabs.

Memory utilization, %:

tnt_slab_quota_used_ratio tnt_slab_quota_used / tnt_slab_quota_size
tnt_slab_arena_used_ratio tnt_slab_arena_used / tnt_slab_arena_size
tnt_slab_items_used_ratio tnt_slab_items_used / tnt_slab_items_size

Spaces

The following metrics provide specific information about each individual space in a Tarantool instance.

tnt_space_len Number of records in the space. This metric always has 2 labels: {name="test", engine="memtx"}, where name is the name of the space and engine is the engine of the space.
tnt_space_bsize Total number of bytes in all tuples. This metric always has 2 labels: {name="test", engine="memtx"}, where name is the name of the space and engine is the engine of the space.
tnt_space_index_bsize Total number of bytes taken by the index. This metric always has 2 labels: {name="test", index_name="pk"}, where name is the name of the space and index_name is the name of the index.
tnt_space_total_bsize Total size of tuples and all indexes in the space. This metric always has 2 labels: {name="test", engine="memtx"}, where name is the name of the space and engine is the engine of the space.
tnt_vinyl_tuples Total tuple count for vinyl. This metric always has 2 labels: {name="test", engine="vinyl"}, where name is the name of the space and engine is the engine of the space. For vinyl this metric is disabled by default and can be enabled only with global variable setup: rawset(_G, 'include_vinyl_count', true).

Network

Network activity stats. These metrics can be used to monitor network load, usage peaks, and traffic drops.

Sent bytes:

tnt_net_sent_total Bytes sent from the instance over the network since the instance’s start time

Received bytes:

tnt_net_received_total Bytes received by the instance since start time

Connections:

tnt_net_connections_total Number of incoming network connections since the instance’s start time
tnt_net_connections_current Number of active network connections

Requests:

tnt_net_requests_total Number of network requests the instance has handled since its start time
tnt_net_requests_current Number of pending network requests

Requests in progress:

tnt_net_requests_in_progress_total Total count of requests processed by tx thread
tnt_net_requests_in_progress_current Count of requests currently being processed in the tx thread

Requests placed in queues of streams:

tnt_net_requests_in_stream_total Total count of requests, which was placed in queues of streams for all time
tnt_net_requests_in_stream_current Count of requests currently waiting in queues of streams

Since Tarantool 2.10 in each network metric has the label thread, showing per-thread network statistics.

Fibers

Provides the statistics for fibers. If your application creates a lot of fibers, you can use the metrics below to monitor fiber count and memory usage.

tnt_fiber_amount Number of fibers
tnt_fiber_csw Overall number of fiber context switches
tnt_fiber_memalloc Amount of memory reserved for fibers
tnt_fiber_memused Amount of memory used by fibers

Operations

You can collect iproto requests an instance has processed and aggregate them by request type. This may help you find out what operations your clients perform most often.

tnt_stats_op_total Total number of calls since server start

To distinguish between request types, this metric has the operation label. For example, it can look as follows: {operation="select"}. For the possible request types, check the table below.

auth Authentication requests
call Requests to execute stored procedures
delete Delete calls
error Requests resulted in an error
eval Calls to evaluate Lua code
execute Execute SQL calls
insert Insert calls
prepare SQL prepare calls
replace Replace calls
select Select calls
update Update calls
upsert Upsert calls

Replication

Provides the current replication status. Learn more about replication in Tarantool.

tnt_info_lsn LSN of the instance.
tnt_info_vclock LSN number in vclock. This metric always has the label {id="id"}, where id is the instance’s number in the replica set.
tnt_replication_lsn LSN of the tarantool instance. This metric always has labels {id="id", type="type"}, where id is the instance’s number in the replica set, type is master or replica.
tnt_replication_lag Replication lag value in seconds. This metric always has labels {id="id", stream="stream"}, where id is the instance’s number in the replica set, stream is downstream or upstream.
tnt_replication_status This metrics equals 1 when replication status is «follow» and 0 otherwise. This metric always has labels {id="id", stream="stream"}, where id is the instance’s number in the replica set, stream is downstream or upstream.

Runtime

tnt_runtime_lua Lua garbage collector size in bytes
tnt_runtime_used Number of bytes used for the Lua runtime
tnt_runtime_tuple Number of bytes used for the tuples (except tuples owned by memtx and vinyl)

LuaJIT metrics

LuaJIT metrics provide an insight into the work of the Lua garbage collector. These metrics are available in Tarantool 2.6 and later.

General JIT metrics:

lj_jit_snap_restore_total Overall number of snap restores
lj_jit_trace_num Number of JIT traces
lj_jit_trace_abort_total Overall number of abort traces
lj_jit_mcode_size Total size of allocated machine code areas

JIT strings:

lj_strhash_hit_total Number of strings being interned
lj_strhash_miss_total Total number of string allocations

GC steps:

lj_gc_steps_atomic_total Count of incremental GC steps (atomic state)
lj_gc_steps_sweepstring_total Count of incremental GC steps (sweepstring state)
lj_gc_steps_finalize_total Count of incremental GC steps (finalize state)
lj_gc_steps_sweep_total Count of incremental GC steps (sweep state)
lj_gc_steps_propagate_total Count of incremental GC steps (propagate state)
lj_gc_steps_pause_total Count of incremental GC steps (pause state)

Allocations:

lj_gc_strnum Number of allocated string objects
lj_gc_tabnum Number of allocated table objects
lj_gc_cdatanum Number of allocated cdata objects
lj_gc_udatanum Number of allocated udata objects
lj_gc_freed_total Total amount of freed memory
lj_gc_memory Current allocated Lua memory
lj_gc_allocated_total Total amount of allocated memory

CPU metrics

The following metrics provide CPU usage statistics. They are only available on Linux.

tnt_cpu_number Total number of processors configured by the operating system
tnt_cpu_time Host CPU time
tnt_cpu_thread

Tarantool thread CPU time. This metric always has the labels {kind="user", thread_name="tarantool", thread_pid="pid", file_name="init.lua"}, where:

  • kind can be either user or system
  • thread_name is tarantool, wal, iproto, or coio
  • file_name is the entrypoint file name, for example, init.lua.

There are also two cross-platform metrics, which can be obtained with a getrusage() call.

tnt_cpu_user_time Tarantool CPU user time
tnt_cpu_system_time Tarantool CPU system time

Vinyl

Vinyl metrics provide vinyl engine statistics.

Disk

The disk metrics are used to monitor overall data size on disk.

tnt_vinyl_disk_data_size Amount of data in bytes stored in the .run files located in vinyl_dir
tnt_vinyl_disk_index_size Amount of data in bytes stored in the .index files located in vinyl_dir

Regulator

The vinyl regulator decides when to commence disk IO actions. It groups activities in batches so that they are more consistent and efficient.

tnt_vinyl_regulator_dump_bandwidth Estimated average dumping rate, bytes per second. The rate value is initially 10485760 (10 megabytes per second). It is recalculated depending on the the actual rate. Only significant dumps that are larger than 1 MB are used for estimating.
tnt_vinyl_regulator_write_rate Actual average rate of performing write operations, bytes per second. The rate is calculated as a 5-second moving average. If the metric value is gradually going down, this can indicate disk issues.
tnt_vinyl_regulator_rate_limit Write rate limit, bytes per second. The regulator imposes the limit on transactions based on the observed dump/compaction performance. If the metric value is down to approximately 10^5, this indicates issues with the disk or the scheduler.
tnt_vinyl_regulator_dump_watermark Maximum amount of memory in bytes used for in-memory storing of a vinyl LSM tree. When this maximum is accessed, a dump must occur. For details, see Наполнение LSM-дерева. The value is slightly smaller than the amount of memory allocated for vinyl trees, reflected in the vinyl_memory parameter.
tnt_vinyl_regulator_blocked_writers The number of fibers that are blocked waiting for Vinyl level0 memory quota.

Transactional activity

tnt_vinyl_tx_commit Counter of commits (successful transaction ends) Includes implicit commits: for example, any insert operation causes a commit unless it is within a box.begin()–box.commit() block.
tnt_vinyl_tx_rollback Сounter of rollbacks (unsuccessful transaction ends). This is not merely a count of explicit box.rollback() requests – it includes requests that ended with errors.
tnt_vinyl_tx_conflict Counter of conflicts that caused transactions to roll back. The ratio tnt_vinyl_tx_conflict / tnt_vinyl_tx_commit above 5% indicates that vinyl is not healthy. At that moment, you’ll probably see a lot of other problems with vinyl.
tnt_vinyl_tx_read_views Current number of read views – that is, transactions that entered the read-only state to avoid conflict temporarily. Usually the value is 0. If it stays non-zero for a long time, it is indicative of a memory leak.

Memory

The following metrics show state memory areas used by vinyl for caches and write buffers.

tnt_vinyl_memory_tuple_cache Amount of memory in bytes currently used to store tuples (data)
tnt_vinyl_memory_level0 «Level 0» (L0) memory area, bytes. L0 is the area that vinyl can use for in-memory storage of an LSM tree. By monitoring this metric, you can see when L0 is getting close to its maximum (tnt_vinyl_regulator_dump_watermark), at which time a dump will occur. You can expect L0 = 0 immediately after the dump operation is completed.
tnt_vinyl_memory_page_index Amount of memory in bytes currently used to store indexes. If the metric value is close to vinyl_memory, this indicates that vinyl_page_size was chosen incorrectly.
tnt_vinyl_memory_bloom_filter Amount of memory in bytes used by bloom filters.
tnt_vinyl_memory_tuple Total size of memory in bytes occupied by Vinyl tuples. It includes cached tuples and tuples pinned by the Lua world.

Scheduler

The vinyl scheduler invokes the regulator and updates the related variables. This happens once per second.

tnt_vinyl_scheduler_tasks

Number of scheduler dump/compaction tasks. The metric always has label {status = <status_value>}, where <status_value> can be one of the following:

  • inprogress for currently running tasks
  • completed for successfully completed tasks
  • failed for tasks aborted due to errors.
tnt_vinyl_scheduler_dump_time Total time in seconds spent by all worker threads performing dumps.
tnt_vinyl_scheduler_dump_total Counter of dumps completed.

Event loop metrics

Event loop tx thread information:

tnt_ev_loop_time Event loop time (ms)
tnt_ev_loop_prolog_time Event loop prolog time (ms)
tnt_ev_loop_epilog_time Event loop epilog time (ms)

Synchro

Shows the current state of a synchronous replication.

tnt_synchro_queue_owner Instance ID of the current synchronous replication master.
tnt_synchro_queue_term Current queue term.
tnt_synchro_queue_len How many transactions are collecting confirmations now.
tnt_synchro_queue_busy Whether the queue is processing any system entry (CONFIRM/ROLLBACK/PROMOTE/DEMOTE).

Election

Shows the current state of a replica set node in regards to leader election.

tnt_election_state

Election state (mode) of the node. When election is enabled, the node is writable only in the leader state. Possible values:

  • 0 (follower): all the non-leader nodes are called followers
  • 1 (candidate): the nodes that start a new election round are called candidates.
  • 2 (leader): the node that collected a quorum of votes becomes the leader
tnt_election_vote ID of a node the current node votes for. If the value is 0, it means the node hasn’t voted in the current term yet.
tnt_election_leader Leader node ID in the current term. If the value is 0, it means the node doesn’t know which node is the leader in the current term.
tnt_election_term Current election term.
tnt_election_leader_idle Time in seconds since the last interaction with the known leader.

Memtx

Memtx mvcc memory statistics. Transaction manager consists of two parts:

TXN

tnt_memtx_tnx_statements are the transaction statements.

For example, the user started a transaction and made an action in it space:replace{0, 1}. Under the hood, this operation will turn into statement for the current transaction. This metric always has the label {kind="..."}, which has the following possible values:

  • total: the number of bytes that are allocated for the statements of all current transactions.
  • average: average bytes used by transactions for statements (txn.statements.total bytes / number of open transactions).
  • max: the maximum number of bytes used by one the current transaction for statements.
tnt_memtx_tnx_user

In Tarantool C API there is a function box_txn_alloc(). By using this function user can allocate memory for the current transaction. This metric always has the label {kind="..."}, which has the following possible values:

  • total: memory allocated by the box_txn_alloc() function on all current transactions.
  • average: transaction average (total allocated bytes / number of all current transactions).
  • max: the maximum number of bytes allocated by box_txn_alloc() function per transaction.
tnt_memtx_tnx_system

There are internals: logs, savepoints. This metric always has the label {kind="..."}, which has the following possible values:

  • total: memory allocated by internals on all current transactions.
  • average: average allocated memory by internals (total memory / number of all current transactions).
  • max: the maximum number of bytes allocated by internals per transaction.

MVCC

mvcc is responsible for the isolation of transactions. It detects conflicts and makes sure that tuples that are no longer in the space, but read by some transaction (or can be read) have not been deleted.

tnt_memtx_mvcc_trackers

Trackers that keep track of transaction reads. This metric always has the label {kind="..."}, which has the following possible values:

  • total: trackers of all current transactions are allocated in total (in bytes).
  • average: average for all current transactions (total memory bytes / number of transactions).
  • max: maximum trackers allocated per transaction (in bytes).
tnt_memtx_mvcc_conflicts

Allocated in case of transaction conflicts. This metric always has the label {kind="..."}, which has the following possible values:

  • total: bytes allocated for conflicts in total.
  • average: average for all current transactions (total memory bytes / number of transactions).
  • max: maximum bytes allocated for conflicts per transaction.

Tuples

Saved tuples are divided into 3 categories: used, read_view, tracking.

Each category has two metrics:

  • retained tuples - they are no longer in the index, but MVCC does not allow them to be removed.
  • stories - MVCC is based on the story mechanism, almost every tuple has a story. This is a separate metric because even the tuples that are in the index can have a story. So stories and retained need to be measured separately.
tnt_memtx_mvcc_tuples_used_stories

Tuples that are used by active read-write transactions. This metric always has the label {kind="..."}, which has the following possible values:

  • count: number of used tuples / number of stories.
  • total: amount of bytes used by stories used tuples.
tnt_memtx_mvcc_tuples_used_retained

Tuples that are used by active read-write transactions. But they are no longer in the index, but MVCC does not allow them to be removed. This metric always has the label {kind="..."}, which has the following possible values:

  • count: number of retained used tuples / number of stories.
  • total: amount of bytes used by retained used tuples.
tnt_memtx_mvcc_tuples_read_view_stories

Tuples that are not used by active read-write transactions, but are used by read-only transactions (i.e. in read view). This metric always has the label {kind="..."}, which has the following possible values:

  • count: number of read_view tuples / number of stories.
  • total: amount of bytes used by stories read_view tuples.
tnt_memtx_mvcc_tuples_read_view_retained

Tuples that are not used by active read-write transactions, but are used by read-only transactions (i.e. in read view). This tuples are no longer in the index, but MVCC does not allow them to be removed. This metric always has the label {kind="..."}, which has the following possible values:

  • count: number of retained read_view tuples / number of stories.
  • total: amount of bytes used by retained read_view tuples.
tnt_memtx_mvcc_tuples_tracking_stories

Tuples that are not directly used by any transactions, but are used by MVCC to track reads. This metric always has the label {kind="..."}, which has the following possible values:

  • count: number of tracking tuples / number of tracking stories.
  • total: amount of bytes used by stories tracking tuples.
tnt_memtx_mvcc_tuples_tracking_retained

Tuples that are not directly used by any transactions, but are used by MVCC to track reads. This tuples are no longer in the index, but MVCC does not allow them to be removed. This metric always has the label {kind="..."}, which has the following possible values:

  • count: number of retained tracking tuples / number of stories.
  • total: amount of bytes used by retained tracking tuples.

Read view statistics

tnt_memtx_tuples_data_total Total amount of memory (in bytes) allocated for data tuples. This includes tnt_memtx_tuples_data_read_view and tnt_memtx_tuples_data_garbage metric values plus tuples that are actually stored in memtx spaces.
tnt_memtx_tuples_data_read_view Memory (in bytes) held for read views.
tnt_memtx_tuples_data_garbage Memory (in bytes) that is unused and scheduled to be freed (freed lazily on memory allocation).
tnt_memtx_index_total Total amount of memory (in bytes) allocated for indexing data. This includes tnt_memtx_index_read_view metric value plus memory used for indexing tuples that are actually stored in memtx spaces.
tnt_memtx_index_read_view Memory (in bytes) held for read views.

Tarantool configuration

Since: 3.0.0.

tnt_config_alerts Count of current instance configuration apply alerts. {level="warn"} label covers warnings and {level="error"} covers errors.
tnt_config_status

The status of current instance configuration apply. status label contains possible status name. Current status has metric value 1, inactive statuses have metric value 0.

# HELP tnt_config_status Tarantool 3 configuration status
# TYPE tnt_config_status gauge
tnt_config_status{status="reload_in_progress",alias="router-001-a"} 0
tnt_config_status{status="uninitialized",alias="router-001-a"} 0
tnt_config_status{status="check_warnings",alias="router-001-a"} 0
tnt_config_status{status="ready",alias="router-001-a"} 1
tnt_config_status{status="check_errors",alias="router-001-a"} 0
tnt_config_status{status="startup_in_progress",alias="router-001-a"} 0

For example, this set of metrics means that current configuration for router-001-a status is ready.

Замечания по поводу некоторых операционных систем

macOS

On macOS, no native system tools for administering Tarantool are supported. The recommended way to administer Tarantool instances is using tt CLI.

Gentoo Linux

В разделе ниже описывается пакет «dev-db/tarantool», установленный из официального оверлея layman (под названием tarantool).

По умолчанию с экземплярами используется директория /etc/tarantool/instances.available, ее можно переопределить в /etc/default/tarantool.

Управление экземплярами Tarantool (запуск/остановка/перезагрузка/проверка статуса и т.д.) можно осуществлять с помощью OpenRC. Рассмотрим пример, как создать экземпляр с управлением OpenRC:

$ cd /etc/init.d
$ ln -s tarantool your_service_name
$ ln -s /usr/share/tarantool/your_service_name.lua /etc/tarantool/instances.available/your_service_name.lua

Проверяем, что работает:

$ /etc/init.d/your_service_name start
$ tail -f -n 100 /var/log/tarantool/your_service_name.log

Руководство по разрешению проблем

Проблема: при выполнении INSERT/UPDATE-запросов возникает ошибка ER_MEMORY_ISSUE

Возможные причины

Решение

У вас есть несколько вариантов действий:

Проблема: Tarantool создает большую нагрузку на CPU

Возможные причины

The transaction processor thread consumes over 60% CPU.

Решение

Attach to the Tarantool instance with tt utility, analyze the query statistics with box.stat() and spot the CPU consumption leader. The following commands can help:

$ # attaching to a Tarantool instance
$ tt connect <instance_name|URI>

-- запрашиваем RPS для вызовов хранимых процедур
tarantool> box.stat().CALL.rps

Критическое значение RPS – 75 000, в случае большого Lua-приложения (модульного приложения, содержащего более 200 строк кода) – 10 000 - 20 000.

-- запрашиваем RPS для запросов указанного типа
tarantool> box.stat().<query_type>.rps

Критическое значение RPS для запросов типа SELECT/INSERT/UPDATE/DELETE – 100 000.

Если основная нагрузка генерируется SELECT-запросами, следует добавить slave-сервер и часть запросов обрабатывать на нем.

Если же нагрузка по большей части приходится на INSERT/UPDATE/DELETE-запросы, рекомендуется провести шардинг базы данных.

Проблема: обработка запросов прекращается по таймауту

Возможные причины

Примечание

Все описанные ниже ситуации можно распознать по записям в журнале Tarantool, начинающимся со слов 'Too long...'.

  1. Быстрые и медленные запросы обрабатываются в одном подключении, что приводит к забиванию readahead-буфера медленными запросами.

    Решение

    У вас есть несколько вариантов действий:

    • Увеличить размер readahead-буфера (box.cfg{readahead}).

      This parameter can be changed on the fly, so you don’t need to restart Tarantool. Attach to the Tarantool instance with tt utility and call box.cfg{} with a new readahead value:

      $ # attaching to a Tarantool instance
$ tt connect <instance_name|URI>

      -- задаем новое значение readahead
tarantool> box.cfg{readahead = 10 * 1024 * 1024}

      Пример расчета: при 1000 RPS, размере одного запроса в 1 Кбайт и максимальном времени обработки одного запроса в 10 секунд минимальный размер readahead-буфера должен равняться 10 Мбайт.

    • Обрабатывать быстрые и медленные запросы в отдельных подключениях (решается на уровне бизнес-логики).

  2. Медленная работа дисков.

    Решение

    Проверить занятость дисков (с помощью утилиты iostat, iotop или strace посмотреть на параметр iowait) и попробовать разнести .xlog-файлы и снимки состояния базы данных по разным дискам (т.е. указать разные значения для параметров wal_dir и memtx_dir).

Проблема: параметры репликации lag и idle принимают отрицательные значения

Речь идет о параметрах box.info.replication.(upstream.)lag и box.info.replication.(upstream.)idle из сводной таблицы box.info.replication.

Возможные причины

Не синхронизированы часы на машинах или неправильно работает NTP-сервер.

Решение

Проверить настройки NTP-сервера.

Если проблем с NTP-сервером не обнаружено, то не следует ничего предпринимать, потому что при вычислении лага репликации используются показания системных часов на двух разных машинах, и в случае рассинхронизации может случиться так, что часы удаленного мастер-сервера всегда будут отставать от часов локального экземпляра Tarantool.

Проблема: общие параметры репликации не совпадают на репликах в рамках одного кластера

Речь идет о кластере, состоящем из одного мастера и нескольких реплик. В таком случае значения общих параметров из сводной таблицы box.info.replication, например box.info.replication.lsn, должны приходить с мастера и должны быть одинаковыми на всех репликах. Если такие параметры не совпадают, это свидетельствует о наличии проблем.

Возможные причины

Сбой репликации.

Решение

Перезапустить репликацию.

Проблема: репликация мастер-мастер остановлена

Речь идет о том, что параметр box.info.replication(.upstream).status имеет значение stopped.

Возможные причины

В репликационном кластере, состоящем из двух мастер-серверов, один из серверов попытался выполнить действие, уже выполненное другим сервером, – например, повторно вставить кортеж с таким же уникальным ключом (распознается по ошибке вида 'Duplicate key exists in unique index 'primary' in space <space_name>').

Решение

This issue can be fixed in two ways:

Then, restart replication as described in Restarting replication.

Проблема: Tarantool работает заметно медленнее, чем раньше

Возможные причины

Неэффективное использование памяти (память занята большим количеством неиспользуемых объектов).

Решение

Запустить сборщик мусора в Lua с помощью функции collectgarbage(count) и измерить время ее выполнения с помощью clock.bench() или clock.proc().

Пример кода для подсчета потребляемой памяти:

$ # attaching to a Tarantool instance
$ tt connect <instance_name|URI>

-- загрузка модуля clock для работы со временем
tarantool> local clock = require 'clock'
-- запускаем таймер
tarantool> local b = clock.proc()
-- запускаем сборку мусора
tarantool> local c = collectgarbage('count')
-- останавливаем таймер по завершении сборки мусора
tarantool> return c, clock.proc() - b

Если возвращаемое clock.proc() значение больше 0.001, это может являться признаком неэффективного использования памяти (активного вмешательства не требуется, но рекомендуется оптимизация кода). Если значение превышает 0.01, необходимо провести подробный анализ кода и оптимизировать потребление памяти.

Если значение больше 0,01, код приложения однозначно необходимо проанализировать на предмет оптимизации использования памяти.

Проблема: Переключатель файберов запрещен в метаметоде __gc

Описание проблемы

Переключатель файберов запрещен в метаметоде __gc, начиная с этого изменения, во избежание неожиданной нехватки памяти в Lua. Однако может потребоваться функция передачи управления для финализации ресурсов, например, для закрытия сокета.

Ниже приведены примеры правильной реализации такой процедуры.

Решение

Для начала есть два простых примера, которые иллюстрируют логику решения:

Далее идет Пример 3, который проиллюстрирует использование модуля sched.lua, — рекомендуемый метод.

Все пояснения приведены в комментариях в листинге кода. -- > обозначает вывод в консоль.

Пример 1

Реализация подходящего финализатора для определенного типа FFI (custom_t).

local ffi = require('ffi')
local fiber = require('fiber')

ffi.cdef('struct custom { int a; };')

local function __custom_gc(self)
  print(("Entered custom GC finalizer for %s... (before yield)"):format(self.a))
  fiber.yield()
  print(("Leaving custom GC finalizer for %s... (after yield)"):format(self.a))
end

local custom_t = ffi.metatype('struct custom', {
  __gc = function(self)
    -- XXX: Do not invoke yielding functions in __gc metamethod.
    -- Create a new fiber to run after the execution leaves
    -- this routine.
    fiber.new(__custom_gc, self)
    print(("Finalization is scheduled for %s..."):format(self.a))
  end
})

-- Create a cdata object of <custom_t> type.
local c = custom_t(42)

-- Remove a single reference to that object to make it subject
-- for GC.
c = nil

-- Run full GC cycle to purge the unreferenced object.
collectgarbage('collect')
-- > Finalization is scheduled for 42...

-- XXX: There is no finalization made until the running fiber
-- yields its execution. Let's do it now.
fiber.yield()
-- > Entered custom GC finalizer for 42... (before yield)
-- > Leaving custom GC finalizer for 42... (after yield)

Пример 2

Implementing a valid finalizer for a particular user type (struct custom).

custom.c

#include <lauxlib.h>
#include <lua.h>
#include <module.h>
#include <stdio.h>

struct custom {
  int a;
};

const char *CUSTOM_MTNAME = "CUSTOM_MTNAME";

/*
 * XXX: Do not invoke yielding functions in __gc metamethod.
 * Create a new fiber to be run after the execution leaves
 * this routine. Unfortunately we can't pass the parameters to the
 * routine to be executed by the created fiber via <fiber_new_ex>.
 * So there is a workaround to load the Lua code below to create
 * __gc metamethod passing the object for finalization via Lua
 * stack to the spawned fiber.
 */
const char *gc_wrapper_constructor = " local fiber = require('fiber')         "
             " print('constructor is initialized')    "
             " return function(__custom_gc)           "
             "   print('constructor is called')       "
             "   return function(self)                "
             "     print('__gc is called')            "
             "     fiber.new(__custom_gc, self)       "
             "     print('Finalization is scheduled') "
             "   end                                  "
             " end                                    "
        ;

int custom_gc(lua_State *L) {
  struct custom *self = luaL_checkudata(L, 1, CUSTOM_MTNAME);
  printf("Entered custom_gc for %d... (before yield)\n", self->a);
  fiber_sleep(0);
  printf("Leaving custom_gc for %d... (after yield)\n", self->a);
  return 0;
}

int custom_new(lua_State *L) {
  struct custom *self = lua_newuserdata(L, sizeof(struct custom));
  luaL_getmetatable(L, CUSTOM_MTNAME);
  lua_setmetatable(L, -2);
  self->a = lua_tonumber(L, 1);
  return 1;
}

static const struct luaL_Reg libcustom_methods [] = {
  { "new", custom_new },
  { NULL, NULL }
};

int luaopen_custom(lua_State *L) {
  int rc;

  /* Create metatable for struct custom type */
  luaL_newmetatable(L, CUSTOM_MTNAME);
  /*
   * Run the constructor initializer for GC finalizer:
   * - load fiber module as an upvalue for GC finalizer
   *   constructor
   * - return GC finalizer constructor on the top of the
   *   Lua stack
   */
  rc = luaL_dostring(L, gc_wrapper_constructor);
  /*
   * Check whether constructor is initialized (i.e. neither
   * syntax nor runtime error is raised).
   */
  if (rc != LUA_OK)
    luaL_error(L, "test module loading failed: constructor init");
  /*
   * Create GC object for <custom_gc> function to be called
   * in scope of the GC finalizer and push it on top of the
   * constructor returned before.
   */
  lua_pushcfunction(L, custom_gc);
  /*
   * Run the constructor with <custom_gc> GCfunc object as
   * a single argument. As a result GC finalizer is returned
   * on the top of the Lua stack.
   */
  rc = lua_pcall(L, 1, 1, 0);
  /*
   * Check whether GC finalizer is created (i.e. neither
   * syntax nor runtime error is raised).
   */
  if (rc != LUA_OK)
    luaL_error(L, "test module loading failed: __gc init");
  /*
   * Assign the returned function as a __gc metamethod to
   * custom type metatable.
   */
  lua_setfield(L, -2, "__gc");

  /*
   * Initialize Lua table for custom module and fill it
   * with the custom methods.
   */
  lua_newtable(L);
  luaL_register(L, NULL, libcustom_methods);
  return 1;
}

custom_c.lua

-- Load custom Lua C extension.
local custom = require('custom')
-- > constructor is initialized
-- > constructor is called

-- Create a userdata object of <struct custom> type.
local c = custom.new(9)

-- Remove a single reference to that object to make it subject
-- for GC.
c = nil

-- Run full GC cycle to purge the unreferenced object.
collectgarbage('collect')
-- > __gc is called
-- > Finalization is scheduled

-- XXX: There is no finalization made until the running fiber
-- yields its execution. Let's do it now.
require('fiber').yield()
-- > Entered custom_gc for 9... (before yield)

-- XXX: Finalizer yields the execution, so now we are here.
print('We are here')
-- > We are here

-- XXX: This fiber finishes its execution, so yield to the
-- remaining fiber to finish the postponed finalization.
-- > Leaving custom_gc for 9... (after yield)

Example 3

It is important to note that the finalizer implementations in the examples above increase pressure on the platform performance by creating a new fiber on each __gc call. To prevent such an excessive fibers spawning, it’s better to start a single «scheduler» fiber and provide the interface to postpone the required asynchronous action.

For this purpose, the module called sched.lua is implemented (see the listing below). It is a part of Tarantool and should be made required in your custom code. The usage example is given in the init.lua file below.

sched.lua

local fiber = require('fiber')

local worker_next_task = nil
local worker_last_task
local worker_fiber
local worker_cv = fiber.cond()

-- XXX: the module is not ready for reloading, so worker_fiber is
-- respawned when sched.lua is purged from package.loaded.

--
-- Worker is a singleton fiber for not urgent delayed execution of
-- functions. Main purpose - schedule execution of a function,
-- which is going to yield, from a context, where a yield is not
-- allowed. Such as an FFI object's GC callback.
--
local function worker_f()
  while true do
    local task
    while true do
      task = worker_next_task
      if task then break end
      -- XXX: Make the fiber wait until the task is added.
      worker_cv:wait()
    end
    worker_next_task = task.next
    task.f(task.arg)
    fiber.yield()
  end
end

local function worker_safe_f()
  pcall(worker_f)
  -- The function <worker_f> never returns. If the execution is
  -- here, this fiber is probably canceled and now is not able to
  -- sleep. Create a new one.
  worker_fiber = fiber.new(worker_safe_f)
end

worker_fiber = fiber.new(worker_safe_f)

local function worker_schedule_task(f, arg)
  local task = { f = f, arg = arg }
  if not worker_next_task then
    worker_next_task = task
  else
    worker_last_task.next = task
  end
  worker_last_task = task
  worker_cv:signal()
end

return {
  postpone = worker_schedule_task
}

init.lua

local ffi = require('ffi')
local fiber = require('fiber')
local sched = require('sched')

local function __custom_gc(self)
  print(("Entered custom GC finalizer for %s... (before yield)"):format(self.a))
  fiber.yield()
  print(("Leaving custom GC finalizer for %s... (after yield)"):format(self.a))
end

ffi.cdef('struct custom { int a; };')
local custom_t = ffi.metatype('struct custom', {
  __gc = function(self)
    -- XXX: Do not invoke yielding functions in __gc metamethod.
    -- Schedule __custom_gc call via sched.postpone to be run
    -- after the execution leaves this routine.
    sched.postpone(__custom_gc, self)
    print(("Finalization is scheduled for %s..."):format(self.a))
  end
})

-- Create several <custom_t> objects to be finalized later.
local t = { }
for i = 1, 10 do t[i] = custom_t(i) end

-- Run full GC cycle to collect the existing garbage. Nothing is
-- going to be printed, since the table <t> is still "alive".
collectgarbage('collect')

-- Remove the reference to the table and, ergo, all references to
-- the objects.
t = nil

-- Run full GC cycle to collect the table and objects inside it.
-- As a result all <custom_t> objects are scheduled for further
-- finalization, but the finalizer itself (i.e. __custom_gc
-- functions) is not called.
collectgarbage('collect')
-- > Finalization is scheduled for 10...
-- > Finalization is scheduled for 9...
-- > ...
-- > Finalization is scheduled for 2...
-- > Finalization is scheduled for 1...

-- XXX: There is no finalization made until the running fiber
-- yields its execution. Let's do it now.
fiber.yield()
-- > Entered custom GC finalizer for 10... (before yield)

-- XXX: Oops, we are here now, since the scheduler fiber yielded
-- the execution to this one. Check this out.
print("We're here now. Let's continue the scheduled finalization.")
-- > We're here now. Let's continue the finalization

-- OK, wait a second to allow the scheduler to cleanup the
-- remaining garbage.
fiber.sleep(1)
-- > Leaving custom GC finalizer for 10... (after yield)
-- > Entered custom GC finalizer for 9... (before yield)
-- > Leaving custom GC finalizer for 9... (after yield)
-- > ...
-- > Entered custom GC finalizer for 1... (before yield)
-- > Leaving custom GC finalizer for 1... (after yield)

print("Did we finish? I guess so.")
-- > Did we finish? I guess so.

-- Stop the instance.
os.exit(0)

Connectors

Connectors are APIs that allow using Tarantool with various programming languages.

Connectors can be divided into two groups – those maintained by the Tarantool team and those supported by the community. The Tarantool team maintains the following connectors:

All other connectors are community-supported, which means that support for new Tarantool features may be delayed. Find all the available connectors on the Connectors page.

Protocol

Tarantool’s binary protocol was designed with a focus on asynchronous I/O and easy integration with proxies. Each client request starts with a variable-length binary header, containing request id, request type, instance id, log sequence number, and so on.

The mandatory length, present in request header simplifies client or proxy I/O. A response to a request is sent to the client as soon as it is ready. It always carries in its header the same type and id as in the request. The id makes it possible to match a request to a response, even if the latter arrived out of order.

Unless implementing a client driver, you needn’t concern yourself with the complications of the binary protocol. Language-specific drivers provide a friendly way to store domain language data structures in Tarantool. A complete description of the binary protocol is maintained in annotated Backus-Naur form in the source tree. For detailed examples and diagrams of all binary-protocol requests and responses, see Tarantool’s binary protocol.

Packet example

The Tarantool API exists so that a client program can send a request packet to a server instance, and receive a response. Here is an example of a what the client would send for box.space[513]:insert{'A', 'BB'}. The BNF description of the components is on the page about Tarantool’s binary protocol.

Component Byte #0 Byte #1 Byte #2 Byte #3
code for insert 02      
rest of header … … … …
2-digit number: space id cd 02 01  
code for tuple 21      
1-digit number: field count = 2 92      
1-character string: field[1] a1 41    
2-character string: field[2] a2 42 42  

Now, you could send that packet to the Tarantool instance, and interpret the response (the page about Tarantool’s binary protocol has a description of the packet format for responses as well as requests). But it would be easier, and less error-prone, if you could invoke a routine that formats the packet according to typed parameters. Something like response = tarantool_routine("insert", 513, "A", "B");. And that is why APIs exist for drivers for Perl, Python, PHP, and so on.

Setting up the server for connector examples

This chapter has examples that show how to connect to a Tarantool instance via the Perl, PHP, Python, node.js, and C connectors. The examples contain hard code that will work if and only if the following conditions are met:

It is easy to meet all the conditions by starting the instance and executing this script:

box.cfg{listen=3301}
box.schema.space.create('examples',{id=999})
box.space.examples:create_index('primary', {type = 'hash', parts = {1, 'unsigned'}})
box.schema.user.grant('guest','read,write','space','examples')
box.schema.user.grant('guest','read','space','_space')

Interpreting function return values

For all connectors, calling a function via Tarantool causes a return in the MsgPack format. If the function is called using the connector’s API, some conversions may occur. All scalar values are returned as tuples (with a MsgPack type-identifier followed by a value); all non-scalar values are returned as a group of tuples (with a MsgPack array-identifier followed by the scalar values). If the function is called via the binary protocol command layer – «eval» – rather than via the connector’s API, no conversions occur.

In the following example, a Lua function will be created. Since it will be accessed externally by a „guest“ user, a grant of an execute privilege will be necessary. The function returns an empty array, a scalar string, two booleans, and a short integer. The values are the ones described in the table Common Types and MsgPack Encodings.

tarantool> box.cfg{listen=3301}
2016-03-03 18:45:52.802 [27381] main/101/interactive I> ready to accept requests
---
...
tarantool> function f() return {},'a',false,true,127; end
---
...
tarantool> box.schema.func.create('f')
---
...
tarantool> box.schema.user.grant('guest','execute','function','f')
---
...

Here is a C program which calls the function. Although C is being used for the example, the result would be precisely the same if the calling program was written in Perl, PHP, Python, Go, or Java.

#include <stdio.h>
#include <stdlib.h>
#include <tarantool/tarantool.h>
#include <tarantool/tnt_net.h>
#include <tarantool/tnt_opt.h>
void main() {
  struct tnt_stream *tnt = tnt_net(NULL);              /* SETUP */
  tnt_set(tnt, TNT_OPT_URI, "localhost:3301");
   if (tnt_connect(tnt) < 0) {                         /* CONNECT */
       printf("Connection refused\n");
       exit(-1);
   }
   struct tnt_stream *arg; arg = tnt_object(NULL);     /* MAKE REQUEST */
   tnt_object_add_array(arg, 0);
   struct tnt_request *req1 = tnt_request_call(NULL);  /* CALL function f() */
   tnt_request_set_funcz(req1, "f");
   uint64_t sync1 = tnt_request_compile(tnt, req1);
   tnt_flush(tnt);                                     /* SEND REQUEST */
   struct tnt_reply reply;  tnt_reply_init(&reply);    /* GET REPLY */
   tnt->read_reply(tnt, &reply);
   if (reply.code != 0) {
     printf("Call failed %lu.\n", reply.code);
     exit(-1);
   }
   const unsigned char *p= (unsigned char*)reply.data; /* PRINT REPLY */
   while (p < (unsigned char *) reply.data_end)
   {
     printf("%x ", *p);
     ++p;
   }
   printf("\n");
   tnt_close(tnt);                                     /* TEARDOWN */
   tnt_stream_free(arg);
   tnt_stream_free(tnt);
}

When this program is executed, it will print:

dd 0 0 0 5 90 91 a1 61 91 c2 91 c3 91 7f

The first five bytes – dd 0 0 0 5 – are the MsgPack encoding for «32-bit array header with value 5» (see MsgPack specification). The rest are as described in the table Common Types and MsgPack Encodings.

Go

Examples on GitHub: sample_db, go

go-tarantool is the official Go connector for Tarantool. It is not supplied as part of the Tarantool repository and should be installed separately.

This tutorial shows how to use the go-tarantool 2.x library to create a Go application that connects to a remote Tarantool instance, performs CRUD operations, and executes a stored procedure. You can find the full package documentation here: Client in Go for Tarantool.

Примечание

This tutorial shows how to make CRUD requests to a single-instance Tarantool database. To make requests to a sharded Tarantool cluster with the CRUD module, use the crud package’s API.

Sample database configuration

This section describes the configuration of a sample database that allows remote connections:

credentials:
  users:
    sampleuser:
      password: '123456'
      privileges:
      - permissions: [ read, write ]
        spaces: [ bands ]
      - permissions: [ execute ]
        functions: [ get_bands_older_than ]

groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'

app:
  file: 'myapp.lua'

The myapp.lua file looks as follows:

-- Create a space --
box.schema.space.create('bands')

-- Specify field names and types --
box.space.bands:format({
    { name = 'id', type = 'unsigned' },
    { name = 'band_name', type = 'string' },
    { name = 'year', type = 'unsigned' }
})

-- Create indexes --
box.space.bands:create_index('primary', { parts = { 'id' } })
box.space.bands:create_index('band', { parts = { 'band_name' } })
box.space.bands:create_index('year_band', { parts = { { 'year' }, { 'band_name' } } })

-- Create a stored function --
box.schema.func.create('get_bands_older_than', {
    body = [[
    function(year)
        return box.space.bands.index.year_band:select({ year }, { iterator = 'LT', limit = 10 })
    end
    ]]
})

You can find the full example on GitHub: sample_db.

Starting a sample database application

Before creating and starting a client Go application, you need to run the sample_db application using tt start:

$ tt start sample_db

Now you can create a client Go application that makes requests to this database.

Developing a client application

Before you start, make sure you have Go installed on your computer.

Creating an application

  1. Create the hello directory for your application and go to this directory:

    $ mkdir hello
$ cd hello

  2. Initialize a new Go module:

    $ go mod init example/hello

  3. Inside the hello directory, create the hello.go file for application code.

Importing „go-tarantool“ packages

In the hello.go file, declare a main package and import the following packages:

package main

import (
	"context"
	"fmt"
	"github.com/tarantool/go-tarantool/v2"
	_ "github.com/tarantool/go-tarantool/v2/datetime"
	_ "github.com/tarantool/go-tarantool/v2/decimal"
	_ "github.com/tarantool/go-tarantool/v2/uuid"
	"time"
)

The packages for external MsgPack types, such as datetime, decimal, or uuid, are required to parse these types in a response.

Connecting to the database

  1. Declare the main() function:

    func main() {

}

  2. Inside the main() function, add the following code:

    // Connect to the database
ctx, cancel := context.WithTimeout(context.Background(), time.Second)
defer cancel()
dialer := tarantool.NetDialer{
	Address:  "127.0.0.1:3301",
	User:     "sampleuser",
	Password: "123456",
}
opts := tarantool.Opts{
	Timeout: time.Second,
}

conn, err := tarantool.Connect(ctx, dialer, opts)
if err != nil {
	fmt.Println("Connection refused:", err)
	return
}

// Interact with the database
// ...

    This code establishes a connection to a running Tarantool instance on behalf of sampleuser. The conn object can be used to make CRUD requests and execute stored procedures.

Manipulating data

Inserting data

Add the following code to insert four tuples into the bands space:

// Insert data
tuples := [][]interface{}{
	{1, "Roxette", 1986},
	{2, "Scorpions", 1965},
	{3, "Ace of Base", 1987},
	{4, "The Beatles", 1960},
}
var futures []*tarantool.Future
for _, tuple := range tuples {
	request := tarantool.NewInsertRequest("bands").Tuple(tuple)
	futures = append(futures, conn.Do(request))
}
fmt.Println("Inserted tuples:")
for _, future := range futures {
	result, err := future.Get()
	if err != nil {
		fmt.Println("Got an error:", err)
	} else {
		fmt.Println(result)
	}
}

This code makes insert requests asynchronously:

  • The Future structure is used as a handle for asynchronous requests.
  • The NewInsertRequest() method creates an insert request object that is executed by the connection.

Примечание

Making requests asynchronously is the recommended way to perform data operations. Further requests in this tutorial are made synchronously.

Querying data

To get a tuple by the specified primary key value, use NewSelectRequest() to create an insert request object:

// Select by primary key
data, err := conn.Do(
	tarantool.NewSelectRequest("bands").
		Limit(10).
		Iterator(tarantool.IterEq).
		Key([]interface{}{uint(1)}),
).Get()
if err != nil {
	fmt.Println("Got an error:", err)
}
fmt.Println("Tuple selected by the primary key value:", data)

You can also get a tuple by the value of the specified index by using Index():

// Select by secondary key
data, err = conn.Do(
	tarantool.NewSelectRequest("bands").
		Index("band").
		Limit(10).
		Iterator(tarantool.IterEq).
		Key([]interface{}{"The Beatles"}),
).Get()
if err != nil {
	fmt.Println("Got an error:", err)
}
fmt.Println("Tuple selected by the secondary key value:", data)

Updating data

NewUpdateRequest() can be used to update a tuple identified by the primary key as follows:

// Update
data, err = conn.Do(
	tarantool.NewUpdateRequest("bands").
		Key(tarantool.IntKey{2}).
		Operations(tarantool.NewOperations().Assign(1, "Pink Floyd")),
).Get()
if err != nil {
	fmt.Println("Got an error:", err)
}
fmt.Println("Updated tuple:", data)

NewUpsertRequest() can be used to update an existing tuple or insert a new one. In the example below, a new tuple is inserted:

// Upsert
data, err = conn.Do(
	tarantool.NewUpsertRequest("bands").
		Tuple([]interface{}{uint(5), "The Rolling Stones", 1962}).
		Operations(tarantool.NewOperations().Assign(1, "The Doors")),
).Get()
if err != nil {
	fmt.Println("Got an error:", err)
}

In this example, NewReplaceRequest() is used to delete the existing tuple and insert a new one:

// Replace
data, err = conn.Do(
	tarantool.NewReplaceRequest("bands").
		Tuple([]interface{}{1, "Queen", 1970}),
).Get()
if err != nil {
	fmt.Println("Got an error:", err)
}
fmt.Println("Replaced tuple:", data)

Deleting data

NewDeleteRequest() in the example below is used to delete a tuple whose primary key value is 5:

// Delete
data, err = conn.Do(
	tarantool.NewDeleteRequest("bands").
		Key([]interface{}{uint(5)}),
).Get()
if err != nil {
	fmt.Println("Got an error:", err)
}
fmt.Println("Deleted tuple:", data)

Executing stored procedures

To execute a stored procedure, use NewCallRequest():

// Call
data, err = conn.Do(
	tarantool.NewCallRequest("get_bands_older_than").Args([]interface{}{1966}),
).Get()
if err != nil {
	fmt.Println("Got an error:", err)
}
fmt.Println("Stored procedure result:", data)

Closing the connection

The CloseGraceful() method can be used to close the connection when it is no longer needed:

// Close connection
conn.CloseGraceful()
fmt.Println("Connection is closed")

Примечание

You can find the example with all the requests above on GitHub: go.

Starting a client application

  1. Execute the following go get commands to update dependencies in the go.mod file:

    $ go get github.com/tarantool/go-tarantool/v2
$ go get github.com/tarantool/go-tarantool/v2/decimal
$ go get github.com/tarantool/go-tarantool/v2/uuid

  2. To run the resulting application, execute the go run command in the application directory:

    $ go run .
Inserted tuples:
[[1 Roxette 1986]]
[[2 Scorpions 1965]]
[[3 Ace of Base 1987]]
[[4 The Beatles 1960]]
Tuple selected by the primary key value: [[1 Roxette 1986]]
Tuple selected by the secondary key value: [[4 The Beatles 1960]]
Updated tuple: [[2 Pink Floyd 1965]]
Replaced tuple: [[1 Queen 1970]]
Deleted tuple: [[5 The Rolling Stones 1962]]
Stored procedure result: [[[2 Pink Floyd 1965] [4 The Beatles 1960]]]
Connection is closed

Community Go connectors

Last update: January 2023

There are also the following community-driven Go connectors:

The table below contains a feature comparison for the connectors mentioned above.

  tarantool/go-tarantool viciious/go-tarantool FZambia/tarantool
License BSD 2-Clause MIT BSD 2-Clause
Last update 2023 2022 2022
Documentation README with examples and up-to-date GoDoc README with examples, code comments README with examples
Testing / CI / CD GitHub Actions Travis CI GitHub Actions
GitHub Stars 147 45 14
Static analysis golangci-lint, luacheck golint golangci-lint
Packaging go get go get go get
Code coverage Yes No No
msgpack driver vmihailenco/msgpack/v2 or vmihailenco/msgpack/v5 tinylib/msgp vmihailenco/msgpack/v5
Async work Yes Yes Yes
Schema reload Yes (manual pull) Yes (manual pull) Yes (manual pull)
Space / index names Yes Yes Yes
Tuples as structures Yes (structure and marshall functions must be predefined in Go code) No Yes (structure and marshall functions must be predefined in Go code)
Access tuple fields by names Only if marshalled to structure No Only if marshalled to structure
SQL support Yes No (#18, closed) No
Interactive transactions Yes No No
Varbinary support Yes (with in-built language tools) Yes (with in-built language tools) Yes (decodes to string by default, see #6)
UUID support Yes No No
Decimal support Yes No No
EXT_ERROR support Yes No No
Datetime support Yes No No
box.session.push() responses Yes No (#21) Yes
Session settings Yes No No
Graceful shutdown Yes No No
IPROTO_ID (feature discovering) Yes No No
tarantool/crud support No No No
Connection pool Yes (round-robin failover, no balancing) No No
Transparent reconnecting Yes (see comments in #129) No (handle reconnects explicitly, refer to #11) Yes (see comments in #7)
Transparent request retrying No No No
Watchers Yes No No
Pagination Yes No No
Language features context context context
Miscellaneous Supports tarantool/queue API Can mimic a Tarantool instance (also as replica). Provides instrumentation for reading snapshot and xlog files via snapio module. Implements unpacking of query structs if you want to implement your own iproto proxy API is experimental and breaking changes may happen

Java

There are two Java connectors available:

The following modules support Java libraries and frameworks:

C

tarantool-c is the official C connector for Tarantool. You can find the full library documentation here: Documentation for tarantool-c.

Here follow two examples of using Tarantool’s high-level C API.

Example 1

Here is a complete C program that inserts [99999,'B'] into space examples via the high-level C API.

#include <stdio.h>
#include <stdlib.h>

#include <tarantool/tarantool.h>
#include <tarantool/tnt_net.h>
#include <tarantool/tnt_opt.h>

void main() {
   struct tnt_stream *tnt = tnt_net(NULL);          /* See note = SETUP */
   tnt_set(tnt, TNT_OPT_URI, "localhost:3301");
   if (tnt_connect(tnt) < 0) {                      /* See note = CONNECT */
       printf("Connection refused\n");
       exit(-1);
   }
   struct tnt_stream *tuple = tnt_object(NULL);     /* See note = MAKE REQUEST */
   tnt_object_format(tuple, "[%d%s]", 99999, "B");
   tnt_insert(tnt, 999, tuple);                     /* See note = SEND REQUEST */
   tnt_flush(tnt);
   struct tnt_reply reply;  tnt_reply_init(&reply); /* See note = GET REPLY */
   tnt->read_reply(tnt, &reply);
   if (reply.code != 0) {
       printf("Insert failed %lu.\n", reply.code);
   }
   tnt_close(tnt);                                  /* See below = TEARDOWN */
   tnt_stream_free(tuple);
   tnt_stream_free(tnt);
}

Paste the code into a file named example.c and install tarantool-c. One way to install tarantool-c (using Ubuntu) is:

$ git clone git://github.com/tarantool/tarantool-c.git ~/tarantool-c
$ cd ~/tarantool-c
$ git submodule init
$ git submodule update
$ cmake .
$ make
$ make install

To compile and link the program, run:

$ # sometimes this is necessary:
$ export LD_LIBRARY_PATH=/usr/local/lib
$ gcc -o example example.c -ltarantool

Before trying to run, check that a server instance is listening at localhost:3301 and that the space examples exists, as described earlier. To run the program, say ./example. The program will connect to the Tarantool instance, and will send the request. If Tarantool is not running on localhost with listen address = 3301, the program will print “Connection refused”. If the insert fails, the program will print «Insert failed» and an error number (see all error codes in the source file /src/box/errcode.h).

Here are notes corresponding to comments in the example program.

SETUP

The setup begins by creating a stream.

struct tnt_stream *tnt = tnt_net(NULL);
tnt_set(tnt, TNT_OPT_URI, "localhost:3301");

In this program, the stream will be named tnt. Before connecting on the tnt stream, some options may have to be set. The most important option is TNT_OPT_URI. In this program, the URI is localhost:3301, since that is where the Tarantool instance is supposed to be listening.

Function description:

struct tnt_stream *tnt_net(struct tnt_stream *s)
int tnt_set(struct tnt_stream *s, int option, variant option-value)

CONNECT

Now that the stream named tnt exists and is associated with a URI, this example program can connect to a server instance.

if (tnt_connect(tnt) < 0)
   { printf("Connection refused\n"); exit(-1); }

Function description:

int tnt_connect(struct tnt_stream *s)

The connection might fail for a variety of reasons, such as: the server is not running, or the URI contains an invalid password. If the connection fails, the return value will be -1.

MAKE REQUEST

Most requests require passing a structured value, such as the contents of a tuple.

struct tnt_stream *tuple = tnt_object(NULL);
tnt_object_format(tuple, "[%d%s]", 99999, "B");

In this program, the request will be an INSERT, and the tuple contents will be an integer and a string. This is a simple serial set of values, that is, there are no sub-structures or arrays. Therefore it is easy in this case to format what will be passed using the same sort of arguments that one would use with a C printf() function: %d for the integer, %s for the string, then the integer value, then a pointer to the string value.

Function description:

ssize_t tnt_object_format(struct tnt_stream *s, const char *fmt, ...)

SEND REQUEST

The database-manipulation requests are analogous to the requests in the box library.

tnt_insert(tnt, 999, tuple);
tnt_flush(tnt);

In this program, the choice is to do an INSERT request, so the program passes the tnt_stream that was used for connection (tnt) and the tnt_stream that was set up with tnt_object_format() (tuple).

Function description:

ssize_t tnt_insert(struct tnt_stream *s, uint32_t space, struct tnt_stream *tuple)
ssize_t tnt_replace(struct tnt_stream *s, uint32_t space, struct tnt_stream *tuple)
ssize_t tnt_select(struct tnt_stream *s, uint32_t space, uint32_t index,
                   uint32_t limit, uint32_t offset, uint8_t iterator,
                   struct tnt_stream *key)
ssize_t tnt_update(struct tnt_stream *s, uint32_t space, uint32_t index,
                   struct tnt_stream *key, struct tnt_stream *ops)

GET REPLY

For most requests, the client will receive a reply containing some indication whether the result was successful, and a set of tuples.

struct tnt_reply reply;  tnt_reply_init(&reply);
tnt->read_reply(tnt, &reply);
if (reply.code != 0)
   { printf("Insert failed %lu.\n", reply.code); }

This program checks for success but does not decode the rest of the reply.

Function description:

struct tnt_reply *tnt_reply_init(struct tnt_reply *r)
tnt->read_reply(struct tnt_stream *s, struct tnt_reply *r)
void tnt_reply_free(struct tnt_reply *r)

TEARDOWN

When a session ends, the connection that was made with tnt_connect() should be closed, and the objects that were made in the setup should be destroyed.

tnt_close(tnt);
tnt_stream_free(tuple);
tnt_stream_free(tnt);

Function description:

void tnt_close(struct tnt_stream *s)
void tnt_stream_free(struct tnt_stream *s)

Example 2

Here is a complete C program that selects, using index key [99999], from space examples via the high-level C API. To display the results, the program uses functions in the MsgPuck library which allow decoding of MessagePack arrays.

#include <stdio.h>
#include <stdlib.h>
#include <tarantool/tarantool.h>
#include <tarantool/tnt_net.h>
#include <tarantool/tnt_opt.h>

#define MP_SOURCE 1
#include <msgpuck.h>

void main() {
    struct tnt_stream *tnt = tnt_net(NULL);
    tnt_set(tnt, TNT_OPT_URI, "localhost:3301");
    if (tnt_connect(tnt) < 0) {
        printf("Connection refused\n");
        exit(1);
    }
    struct tnt_stream *tuple = tnt_object(NULL);
    tnt_object_format(tuple, "[%d]", 99999); /* tuple = search key */
    tnt_select(tnt, 999, 0, UINT32_MAX, 0, 0, tuple);
    tnt_flush(tnt);
    struct tnt_reply reply; tnt_reply_init(&reply);
    tnt->read_reply(tnt, &reply);
    if (reply.code != 0) {
        printf("Select failed.\n");
        exit(1);
    }
    char field_type;
    field_type = mp_typeof(*reply.data);
    if (field_type != MP_ARRAY) {
        printf("no tuple array\n");
        exit(1);
    }
    long unsigned int row_count;
    uint32_t tuple_count = mp_decode_array(&reply.data);
    printf("tuple count=%u\n", tuple_count);
    unsigned int i, j;
    for (i = 0; i < tuple_count; ++i) {
        field_type = mp_typeof(*reply.data);
        if (field_type != MP_ARRAY) {
            printf("no field array\n");
            exit(1);
        }
        uint32_t field_count = mp_decode_array(&reply.data);
        printf("  field count=%u\n", field_count);
        for (j = 0; j < field_count; ++j) {
            field_type = mp_typeof(*reply.data);
            if (field_type == MP_UINT) {
                uint64_t num_value = mp_decode_uint(&reply.data);
                printf("    value=%lu.\n", num_value);
            } else if (field_type == MP_STR) {
                const char *str_value;
                uint32_t str_value_length;
                str_value = mp_decode_str(&reply.data, &str_value_length);
                printf("    value=%.*s.\n", str_value_length, str_value);
            } else {
                printf("wrong field type\n");
                exit(1);
            }
        }
    }
    tnt_close(tnt);
    tnt_stream_free(tuple);
    tnt_stream_free(tnt);
}

Similarly to the first example, paste the code into a file named example2.c.

To compile and link the program, say:

$ gcc -o example2 example2.c -ltarantool

To run the program, say ./example2.

The two example programs only show a few requests and do not show all that’s necessary for good practice. See more in the tarantool-c documentation at GitHub.

Python

Examples on GitHub: sample_db, python

tarantool-python is the official Python connector for Tarantool. It is not supplied as part of the Tarantool repository and must be installed separately.

The tutorial shows how to use the tarantool-python library to create a Python script that connects to a remote Tarantool instance, performs CRUD operations, and executes a stored procedure. You can find the full package documentation here: Python client library for Tarantool.

Примечание

This tutorial shows how to make CRUD requests to a single-instance Tarantool database. To make requests to a sharded Tarantool cluster with the CRUD module, use the tarantool.crud module’s API.

Sample database configuration

This section describes the configuration of a sample database that allows remote connections:

credentials:
  users:
    sampleuser:
      password: '123456'
      privileges:
      - permissions: [ read, write ]
        spaces: [ bands ]
      - permissions: [ execute ]
        functions: [ get_bands_older_than ]

groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'

app:
  file: 'myapp.lua'

The myapp.lua file looks as follows:

-- Create a space --
box.schema.space.create('bands')

-- Specify field names and types --
box.space.bands:format({
    { name = 'id', type = 'unsigned' },
    { name = 'band_name', type = 'string' },
    { name = 'year', type = 'unsigned' }
})

-- Create indexes --
box.space.bands:create_index('primary', { parts = { 'id' } })
box.space.bands:create_index('band', { parts = { 'band_name' } })
box.space.bands:create_index('year_band', { parts = { { 'year' }, { 'band_name' } } })

-- Create a stored function --
box.schema.func.create('get_bands_older_than', {
    body = [[
    function(year)
        return box.space.bands.index.year_band:select({ year }, { iterator = 'LT', limit = 10 })
    end
    ]]
})

You can find the full example on GitHub: sample_db.

Starting a sample database application

Before creating and starting a client Python application, you need to run the sample_db application using tt start:

$ tt start sample_db

Now you can create a client Python application that makes requests to this database.

Developing a client application

Before you start, make sure you have Python installed on your computer.

Creating an application

  1. Create the hello directory for your application and go to this directory:

    $ mkdir hello
$ cd hello

  2. Create and activate a Python virtual environment:

    $ python -m venv .venv
$ source .venv/bin/activate

  3. Install the tarantool module:

    $ pip install tarantool

  4. Inside the hello directory, create the hello.py file for application code.

Importing „tarantool“

In the hello.py file, import the tarantool package:

import tarantool

Connecting to the database

Add the following code:

# Connect to the database
conn = tarantool.Connection(host='127.0.0.1',
                            port=3301,
                            user='sampleuser',
                            password='123456')

This code establishes a connection to a running Tarantool instance on behalf of sampleuser. The conn object can be used to make CRUD requests and execute stored procedures.

Manipulating data

Inserting data

Add the following code to insert four tuples into the bands space:

# Insert data
tuples = [(1, 'Roxette', 1986),
          (2, 'Scorpions', 1965),
          (3, 'Ace of Base', 1987),
          (4, 'The Beatles', 1960)]
print("Inserted tuples:")
for tuple in tuples:
    response = conn.insert(space_name='bands', values=tuple)
    print(response[0])

Connection.insert() is used to insert a tuple to the space.

Querying data

To get a tuple by the specified primary key value, use Connection.select():

# Select by primary key
response = conn.select(space_name='bands', key=1)
print('Tuple selected by the primary key value:', response[0])

You can also get a tuple by the value of the specified index using the index argument:

# Select by secondary key
response = conn.select(space_name='bands', key='The Beatles', index='band')
print('Tuple selected by the secondary key value:', response[0])

Updating data

Connection.update() can be used to update a tuple identified by the primary key as follows:

# Update
response = conn.update(space_name='bands',
                       key=2,
                       op_list=[('=', 'band_name', 'Pink Floyd')])
print('Updated tuple:', response[0])

Connection.upsert() updates an existing tuple or inserts a new one. In the example below, a new tuple is inserted:

# Upsert
conn.upsert(space_name='bands',
            tuple_value=(5, 'The Rolling Stones', 1962),
            op_list=[('=', 'band_name', 'The Doors')])

In this example, Connection.replace() deletes the existing tuple and inserts a new one:

# Replace
response = conn.replace(space_name='bands', values=(1, 'Queen', 1970))
print('Replaced tuple:', response[0])

Deleting data

Connection.delete() in the example below deletes a tuple whose primary key value is 5:

# Delete
response = conn.delete(space_name='bands', key=5)
print('Deleted tuple:', response[0])

Executing stored procedures

To execute a stored procedure, use Connection.call():

# Call
response = conn.call('get_bands_older_than', 1966)
print('Stored procedure result:', response[0])

Closing the connection

The Connection.close() method can be used to close the connection when it is no longer needed:

# Close connection
conn.close()
print('Connection is closed')

Примечание

You can find the example with all the requests above on GitHub: python.

Starting a client application

To run the resulting application, pass the script name to the python command:

$ python hello.py
Inserted tuples:
[1, 'Roxette', 1986]
[2, 'Scorpions', 1965]
[3, 'Ace of Base', 1987]
[4, 'The Beatles', 1960]
Tuple selected by the primary key value: [1, 'Roxette', 1986]
Tuple selected by the secondary key value: [4, 'The Beatles', 1960]
Updated tuple: [2, 'Pink Floyd', 1965]
Replaced tuple: [1, 'Queen', 1970]
Deleted tuple: [5, 'The Rolling Stones', 1962]
Stored procedure result: [[2, 'Pink Floyd', 1965], [4, 'The Beatles', 1960]]
Connection is closed

Community Python connectors

Last update: September 2023

There are also several community-driven Python connectors:

The table below contains a feature comparison for asynctnt and tarantool-python.

Parameter igorcoding/asynctnt tarantool/tarantool-python
License Apache License 2.0 BSD-2
Is maintained Yes Yes
Known Issues None None
Documentation Yes (github.io) Yes (readthedocs and tarantool.io)
Testing / CI / CD GitHub Actions GitHub Actions
GitHub Stars 73 92
Static Analysis Yes (Flake8) Yes (Flake8, Pylint)
Packaging pip pip, deb, rpm
Code coverage Yes Yes
Support asynchronous mode Yes, asyncio No
Batching support No Yes (with CRUD API)
Schema reload Yes (automatically, see auto_refetch_schema) Yes (automatically)
Space / index names Yes Yes
Access tuple fields by names Yes No
SQL support Yes Yes
Interactive transactions Yes No (issue #163)
Varbinary support Yes (in MP_BIN fields) Yes
Decimal support Yes Yes
UUID support Yes Yes
EXT_ERROR support Yes Yes
Datetime support Yes Yes
Interval support No (issue #30) Yes
box.session.push() responses Yes Yes
Session settings No No
Graceful shutdown No No
IPROTO_ID (feature discovery) Yes Yes
CRUD support No Yes
Transparent request retrying No No
Transparent reconnecting Autoreconnect Yes (reconnect_max_attempts, reconnect_delay), checking of connection liveness
Connection pool No Yes (with master discovery)
Support of PEP 249 – Python Database API Specification v2.0 No Yes
Encrypted connection (Enterprise Edition) No (issue #22) Yes

C++

tntcxx is the official C++ connector for Tarantool.

Connecting to Tarantool from C++

To simplify the start of your working with the Tarantool C++ connector, we will use the example application from the connector repository. We will go step by step through the application code and explain what each part does.

The following main topics are discussed in this manual:

Pre-requisites

To go through this Getting Started exercise, you need the following pre-requisites to be done:

Installation

The Tarantool C++ connector is currently supported for Linux only.

The connector itself is a header-only library, so, it doesn’t require installation and building as such. All you need is to clone the connector source code and embed it in your C++ project.

Also, make sure you have other necessary software and Tarantool installed.

  1. Make sure you have the following third-party software. If you miss some of the items, install them:

  2. If you don’t have Tarantool on your OS, install it in one of the ways:

  3. Clone the Tarantool C++ connector repository.

    git clone git@github.com:tarantool/tntcxx.git

Starting Tarantool and creating a database

Start Tarantool locally or in Docker and create a space with the following schema and index:

box.cfg{listen = 3301}
t = box.schema.space.create('t')
t:format({
         {name = 'id', type = 'unsigned'},
         {name = 'a', type = 'string'},
         {name = 'b', type = 'number'}
         })
t:create_index('primary', {
         type = 'hash',
         parts = {'id'}
         })

Важно

Do not close the terminal window where Tarantool is running. You will need it later to connect to Tarantool from your C++ application.

Setting up access rights

To be able to execute the necessary operations in Tarantool, you need to grant the guest user with the read-write rights. The simplest way is to grant the user with the super role:

box.schema.user.grant('guest', 'super')

Connecting to Tarantool

There are three main parts of the C++ connector: the IO-zero-copy buffer, the msgpack encoder/decoder, and the client that handles requests.

To set up connection to a Tarantool instance from a C++ application, you need to do the following:

Embedding connector

Embed the connector in your C++ application by including the main header:

#include "../src/Client/Connector.hpp"

Instantiating objects

First, we should create a connector client. It can handle many connections to Tarantool instances asynchronously. To instantiate a client, you should specify the buffer and the network provider implementations as template parameters. The connector’s main class has the following signature:

template<class BUFFER, class NetProvider = EpollNetProvider<BUFFER>>
class Connector;

The buffer is parametrized by allocator. It means that users can choose which allocator will be used to provide memory for the buffer’s blocks. Data is organized into a linked list of blocks of fixed size that is specified as the template parameter of the buffer.

You can either implement your own buffer or network provider or use the default ones as we do in our example. So, the default connector instantiation looks as follows:

using Buf_t = tnt::Buffer<16 * 1024>;
#include "../src/Client/LibevNetProvider.hpp"
using Net_t = LibevNetProvider<Buf_t, DefaultStream>;

Connector<Buf_t, Net_t> client;

To use the BUFFER class, the buffer header should also be included:

#include "../src/Buffer/Buffer.hpp"

A client itself is not enough to work with Tarantool instances–we also need to create connection objects. A connection also takes the buffer and the network provider as template parameters. Note that they must be the same as ones of the client:

Connection<Buf_t, Net_t> conn(client);

Connecting

Our Tarantool instance is listening to the 3301 port on localhost. Let’s define the corresponding variables as well as the WAIT_TIMEOUT variable for connection timeout.

const char *address = "127.0.0.1";
int port = 3301;
int WAIT_TIMEOUT = 1000; //milliseconds

To connect to the Tarantool instance, we should invoke the Connector::connect() method of the client object and pass three arguments: connection instance, address, and port.

int rc = client.connect(conn, {.address = address,
			       .service = std::to_string(port),
			       /*.user = ...,*/
			       /*.passwd = ...,*/
			       /* .transport = STREAM_SSL, */});

Error handling

Implementation of the connector is exception free, so we rely on the return codes: in case of fail, the connect() method returns rc < 0. To get the error message corresponding to the last error occured during communication with the instance, we can invoke the Connection::getError() method.

if (rc != 0) {
	//assert(conn.getError().saved_errno != 0);
	std::cerr << conn.getError().msg << std::endl;
	return -1;
}

To reset connection after errors, that is, to clean up the error message and connection status, the Connection::reset() method is used.

Working with requests

In this section, we will show how to:

We will also go through the case of having several connections and executing a number of requests from different connections simultaneously.

In our example C++ application, we execute the following types of requests:

Примечание

Examples on other request types, namely, insert, delete, upsert, and update, will be added to this manual later.

Each request method returns a request ID that is a sort of future. This ID can be used to get the response message when it is ready. Requests are queued in the output buffer of connection until the Connector::wait() method is called.

Preparing requests

At this step, requests are encoded in the MessagePack format and saved in the output connection buffer. They are ready to be sent but the network communication itself will be done later.

Let’s remind that for the requests manipulating with data we are dealing with the Tarantool space t created earlier, and the space has the following format:

t:format({
         {name = 'id', type = 'unsigned'},
         {name = 'a', type = 'string'},
         {name = 'b', type = 'number'}
         })

ping

rid_t ping = conn.ping();

replace

Equals to Lua request <space_name>:replace(pk_value, "111", 1).

uint32_t space_id = 512;
int pk_value = 666;
std::tuple data = std::make_tuple(pk_value /* field 1*/, "111" /* field 2*/, 1.01 /* field 3*/);
rid_t replace = conn.space[space_id].replace(data);

select

Equals to Lua request <space_name>.index[0]:select({pk_value}, {limit = 1}).

uint32_t index_id = 0;
uint32_t limit = 1;
uint32_t offset = 0;
IteratorType iter = IteratorType::EQ;
auto i = conn.space[space_id].index[index_id];
rid_t select = i.select(std::make_tuple(pk_value), limit, offset, iter);

Sending requests

To send requests to the server side, invoke the client.wait() method.

client.wait(conn, ping, WAIT_TIMEOUT);

The wait() method takes the connection to poll, the request ID, and, optionally, the timeout as parameters. Once a response for the specified request is ready, wait() terminates. It also provides a negative return code in case of system related fails, for example, a broken or timeouted connection. If wait() returns 0, then a response has been received and expected to be parsed.

Now let’s send our requests to the Tarantool instance. The futureIsReady() function checks availability of a future and returns true or false.

while (! conn.futureIsReady(ping)) {
	/*
	 * wait() is the main function responsible for sending/receiving
	 * requests and implements event-loop under the hood. It may
	 * fail due to several reasons:
	 *  - connection is timed out;
	 *  - connection is broken (e.g. closed);
	 *  - epoll is failed.
	 */
	if (client.wait(conn, ping, WAIT_TIMEOUT) != 0) {
		std::cerr << conn.getError().msg << std::endl;
		conn.reset();
	}
}

Receiving responses

To get the response when it is ready, use the Connection::getResponse() method. It takes the request ID and returns an optional object containing the response. If the response is not ready yet, the method returns std::nullopt. Note that on each future, getResponse() can be called only once: it erases the request ID from the internal map once it is returned to a user.

A response consists of a header and a body (response.header and response.body). Depending on success of the request execution on the server side, body may contain either runtime error(s) accessible by response.body.error_stack or data (tuples)–response.body.data. In turn, data is a vector of tuples. However, tuples are not decoded and come in the form of pointers to the start and the end of msgpacks. See the «Decoding and reading the data» section to understand how to decode tuples.

There are two options for single connection it regards to receiving responses: we can either wait for one specific future or for all of them at once. We’ll try both options in our example. For the ping request, let’s use the first option.

std::optional<Response<Buf_t>> response = conn.getResponse(ping);
/*
 * Since conn.futureIsReady(ping) returned <true>, then response
 * must be ready.
 */
assert(response != std::nullopt);
/*
 * If request is successfully executed on server side, response
 * will contain data (i.e. tuple being replaced in case of :replace()
 * request or tuples satisfying search conditions in case of :select();
 * responses for pings contain nothing - empty map).
 * To tell responses containing data from error responses, one can
 * rely on response code storing in the header or check
 * Response->body.data and Response->body.error_stack members.
 */
printResponse<Buf_t>(*response);

For the replace and select requests, let’s examine the option of waiting for both futures at once.

/* Let's wait for both futures at once. */
std::vector<rid_t> futures(2);
futures[0] = replace;
futures[1] = select;
/* No specified timeout means that we poll futures until they are ready.*/
client.waitAll(conn, futures);
for (size_t i = 0; i < futures.size(); ++i) {
	assert(conn.futureIsReady(futures[i]));
	response = conn.getResponse(futures[i]);
	assert(response != std::nullopt);
	printResponse<Buf_t>(*response);
}

Several connections at once

Now, let’s have a look at the case when we establish two connections to Tarantool instance simultaneously.

/* Let's create another connection. */
Connection<Buf_t, Net_t> another(client);
if (client.connect(another, {.address = address,
			     .service = std::to_string(port),
			     /* .transport = STREAM_SSL, */}) != 0) {
	std::cerr << conn.getError().msg << std::endl;
	return -1;
}
/* Simultaneously execute two requests from different connections. */
rid_t f1 = conn.ping();
rid_t f2 = another.ping();
/*
 * waitAny() returns the first connection received response.
 * All connections registered via :connect() call are participating.
 */
std::optional<Connection<Buf_t, Net_t>> conn_opt = client.waitAny(WAIT_TIMEOUT);
Connection<Buf_t, Net_t> first = *conn_opt;
if (first == conn) {
	assert(conn.futureIsReady(f1));
	(void) f1;
} else {
	assert(another.futureIsReady(f2));
	(void) f2;
}

Closing connections

Finally, a user is responsible for closing connections.

client.close(conn);
client.close(another);

Building and launching C++ application

Now, we are going to build our example C++ application, launch it to connect to the Tarantool instance and execute all the requests defined.

Make sure you are in the root directory of the cloned C++ connector repository. To build the example application:

cd examples
cmake .
make

Make sure the Tarantool session you started earlier is running. Launch the application:

./Simple

As you can see from the execution log, all the connections to Tarantool defined in our application have been established and all the requests have been executed successfully.

Decoding and reading the data

Responses from a Tarantool instance contain raw data, that is, the data encoded into the MessagePack tuples. To decode client’s data, the user has to write their own decoders (readers) based on the database schema and include them in one’s application:

#include "Reader.hpp"

To show the logic of decoding a response, we will use the reader from our example.

First, the structure corresponding our example space format is defined:

/**
 * Corresponds to tuples stored in user's space:
 * box.execute("CREATE TABLE t (id UNSIGNED PRIMARY KEY, a TEXT, d DOUBLE);")
 */
struct UserTuple {
	uint64_t field1;
	std::string field2;
	double field3;

	static constexpr auto mpp = std::make_tuple(
		&UserTuple::field1, &UserTuple::field2, &UserTuple::field3);
};

Base reader prototype

Prototype of the base reader is given in src/mpp/Dec.hpp:

template <class BUFFER, Type TYPE>
struct SimpleReaderBase : DefaultErrorHandler {
   using BufferIterator_t = typename BUFFER::iterator;
   /* Allowed type of values to be parsed. */
   static constexpr Type VALID_TYPES = TYPE;
   BufferIterator_t* StoreEndIterator() { return nullptr; }
};

Every new reader should inherit from it or directly from the DefaultErrorHandler.

Parsing values

To parse a particular value, we should define the Value() method. First two arguments of the method are common and unused as a rule, but the third one defines the parsed value. In case of POD (Plain Old Data) structures, it’s enough to provide a byte-to-byte copy. Since there are fields of three different types in our schema, let’s define the corresponding Value() functions:

Parsing array

It’s also important to understand that a tuple itself is wrapped in an array, so, in fact, we should parse the array first. Let’s define another reader for that purpose.

Setting reader

The SetReader() method sets the reader that is invoked while each of the array’s entries is parsed. To make two readers defined above work, we should create a decoder, set its iterator to the position of the encoded tuple, and invoke the Read() method (the code block below is from the example application).

C++ connector API

The official C++ connector for Tarantool is located in the tanartool/tntcxx repository.

It is not supplied as part of the Tarantool repository and requires additional actions for usage. The connector itself is a header-only library and, as such, doesn’t require installation and building. All you need is to clone the connector source code and embed it in your C++ project. See the C++ connector Getting started document for details and examples.

Below is the description of the connector public API.

Connector class

template<class BUFFER, class NetProvider = EpollNetProvider<BUFFER>>
class Connector

The Connector class is a template class that defines a connector client which can handle many connections to Tarantool instances asynchronously.

To instantiate a client, you should specify the buffer and the network provider implementations as template parameters. You can either implement your own buffer or network provider or use the default ones.

The default connector instantiation looks as follows:

using Buf_t = tnt::Buffer<16 * 1024>;
using Net_t = EpollNetProvider<Buf_t >;
Connector<Buf_t, Net_t> client;

Public methods

int connect(Connection<BUFFER, NetProvider> &conn, const std::string_view &addr, unsigned port, size_t timeout = DEFAULT_CONNECT_TIMEOUT)

Connects to a Tarantool instance that is listening on addr:port. On successful connection, the method returns 0. If the host doesn’t reply within the timeout period or another error occurs, it returns -1. Then, Connection.getError() gives the error message.

Параметры:
  • conn – object of the Connection class.
  • addr – address of the host where a Tarantool instance is running.
  • port – port that a Tarantool instance is listening on.
  • timeout – connection timeout, seconds. Optional. Defaults to 2.
Результат:

0 on success, or -1 otherwise.
Rtype:

int

Possible errors:

  • connection timeout
  • refused to connect (due to incorrect address or/and port)
  • system errors: a socket can’t be created; failure of any of the system calls (fcntl, select, send, receive).

Example:

using Buf_t = tnt::Buffer<16 * 1024>;
using Net_t = EpollNetProvider<Buf_t >;

Connector<Buf_t, Net_t> client;
Connection<Buf_t, Net_t> conn(client);

int rc = client.connect(conn, "127.0.0.1", 3301);
int wait(Connection<BUFFER, NetProvider> &conn, rid_t future, int timeout = 0)

The main method responsible for sending a request and checking the response readiness.

You should prepare a request beforehand by using the necessary method of the Connection class, such as ping() and so on, which encodes the request in the MessagePack format and saves it in the output connection buffer.

wait() sends the request and is polling the future for the response readiness. Once the response is ready, wait() returns 0. If at timeout the response isn’t ready or another error occurs, it returns -1. Then, Connection.getError() gives the error message. timeout = 0 means the method is polling the future until the response is ready.

Параметры:
  • conn – object of the Connection class.
  • future – request ID returned by a request method of the Connection class, such as, ping() and so on.
  • timeout – waiting timeout, milliseconds. Optional. Defaults to 0.
Результат:

0 on receiving a response, or -1 otherwise.
Rtype:

int

Possible errors:

  • timeout exceeded
  • other possible errors depend on a network provider used. If the EpollNetProvider is used, failing of the poll, read, and write system calls leads to system errors, such as, EBADF, ENOTSOCK, EFAULT, EINVAL, EPIPE, and ENOTCONN (EWOULDBLOCK and EAGAIN don’t occur in this case).

Example:

client.wait(conn, ping, WAIT_TIMEOUT)
void waitAll(Connection<BUFFER, NetProvider> &conn, rid_t *futures, size_t future_count, int timeout = 0)

Similar to wait(), the method sends the requests prepared and checks the response readiness, but can send several different requests stored in the futures array. Exceeding the timeout leads to an error; Connection.getError() gives the error message. timeout = 0 means the method is polling the futures until all the responses are ready.

Параметры:
  • conn – object of the Connection class.
  • futures – array with the request IDs returned by request methods of the Connection class, such as, ping() and so on.
  • future_count – size of the futures array.
  • timeout – waiting timeout, milliseconds. Optional. Defaults to 0.
Результат:

none
Rtype:

none

Possible errors:

  • timeout exceeded
  • other possible errors depend on a network provider used. If the EpollNetProvider is used, failing of the poll, read, and write system calls leads to system errors, such as, EBADF, ENOTSOCK, EFAULT, EINVAL, EPIPE, and ENOTCONN (EWOULDBLOCK and EAGAIN don’t occur in this case).

Example:

rid_t futures[2];
futures[0] = replace;
futures[1] = select;

client.waitAll(conn, (rid_t *) &futures, 2);
Connection<BUFFER, NetProvider> *waitAny(int timeout = 0)

Sends all requests that are prepared at the moment and is waiting for any first response to be ready. Upon the response readiness, waitAny() returns the corresponding connection object. If at timeout no response is ready or another error occurs, it returns nullptr. Then, Connection.getError() gives the error message. timeout = 0 means no time limitation while waiting for the response readiness.

Параметры:timeout – waiting timeout, milliseconds. Optional. Defaults to 0.
Результат:object of the Connection class on success, or nullptr on error.
Rtype:Connection<BUFFER, NetProvider>*

Possible errors:

  • timeout exceeded
  • other possible errors depend on a network provider used. If the EpollNetProvider is used, failing of the poll, read, and write system calls leads to system errors, such as, EBADF, ENOTSOCK, EFAULT, EINVAL, EPIPE, and ENOTCONN (EWOULDBLOCK and EAGAIN don’t occur in this case).

Example:

rid_t f1 = conn.ping();
rid_t f2 = another_conn.ping();

Connection<Buf_t, Net_t> *first = client.waitAny(WAIT_TIMEOUT);
if (first == &conn) {
    assert(conn.futureIsReady(f1));
} else {
    assert(another_conn.futureIsReady(f2));
}
void close(Connection<BUFFER, NetProvider> &conn)

Closes the connection established earlier by the connect() method.

Параметры:conn – connection object of the Connection class.
Результат:none
Rtype:none

Possible errors: none.

Example:

client.close(conn);

Connection class

template<class BUFFER, class NetProvider>
class Connection

The Connection class is a template class that defines a connection objects which is required to interact with a Tarantool instance. Each connection object is bound to a single socket.

Similar to a connector client, a connection object also takes the buffer and the network provider as template parameters, and they must be the same as ones of the client. For example:

//Instantiating a connector client
using Buf_t = tnt::Buffer<16 * 1024>;
using Net_t = EpollNetProvider<Buf_t >;
Connector<Buf_t, Net_t> client;

//Instantiating connection objects
Connection<Buf_t, Net_t> conn01(client);
Connection<Buf_t, Net_t> conn02(client);

The Connection class has two nested classes, namely, Space and Index that implement the data-manipulation methods like select(), replace(), and so on.

Public types

typedef size_t rid_t

The alias of the built-in size_t type. rid_t is used for entities that return or contain a request ID.

Public methods

template<class T>
rid_t call(const std::string &func, const T &args)

Executes a call of a remote stored-procedure similar to conn:call(). The method returns the request ID that is used to get the response by getResponse().

Параметры:
  • func – a remote stored-procedure name.
  • args – procedure’s arguments.
Результат:

a request ID
Rtype:

rid_t

Possible errors: none.

Example:

The following function is defined on the Tarantool instance you are connected to:

box.execute("DROP TABLE IF EXISTS t;")
box.execute("CREATE TABLE t(id INT PRIMARY KEY, a TEXT, b DOUBLE);")

function remote_replace(arg1, arg2, arg3)
    return box.space.T:replace({arg1, arg2, arg3})
end

The function call can look as follows:

rid_t f1 = conn.call("remote_replace", std::make_tuple(5, "some_sring", 5.55));
bool futureIsReady(rid_t future)

Checks availability of a request ID (future) returned by any of the request methods, such as, ping() and so on.

futureIsReady() returns true if the future is available or false otherwise.

Параметры:future – a request ID.
Результат:true or false
Rtype:bool

Possible errors: none.

Example:

rid_t ping = conn.ping();
conn.futureIsReady(ping);
std::optional<Response<BUFFER>> getResponse(rid_t future)

The method takes a request ID (future) as an argument and returns an optional object containing a response. If the response is not ready, the method returns std::nullopt. Note that for each future the method can be called only once because it erases the request ID from the internal map as soon as the response is returned to a user.

A response consists of a header (response.header) and a body (response.body). Depending on success of the request execution on the server side, body may contain either runtime errors accessible by response.body.error_stack or data (tuples) accessible by response.body.data. Data is a vector of tuples. However, tuples are not decoded and come in the form of pointers to the start and the end of MessagePacks. For details on decoding the data received, refer to «Decoding and reading the data».

Параметры:future – a request ID
Результат:a response object or std::nullopt
Rtype:std::optional<Response<BUFFER>>

Possible errors: none.

Example:

rid_t ping = conn.ping();
std::optional<Response<Buf_t>> response = conn.getResponse(ping);
std::string &getError()

Returns an error message for the last error occured during the execution of methods of the Connector and Connection classes.

Результат:an error message
Rtype:std::string&

Possible errors: none.

Example:

int rc = client.connect(conn, address, port);

if (rc != 0) {
    std::cerr << conn.getError() << std::endl;
    return -1;
}
void reset()

Resets a connection after errors, that is, cleans up the error message and the connection status.

Результат:none
Rtype:none

Possible errors: none.

Example:

if (client.wait(conn, ping, WAIT_TIMEOUT) != 0) {
    assert(conn.status.is_failed);
    std::cerr << conn.getError() << std::endl;
    conn.reset();
}
rid_t ping()

Prepares a request to ping a Tarantool instance.

The method encodes the request in the MessagePack format and queues it in the output connection buffer to be sent later by one of Connector’s methods, namely, wait(), waitAll(), or waitAny().

Returns the request ID that is used to get the response by the getResponce() method.

Результат:a request ID
Rtype:rid_t

Possible errors: none.

Example:

rid_t ping = conn.ping();

Nested classes and their methods

Space class

class Space : Connection

Space is a nested class of the Connection class. It is a public wrapper to access the data-manipulation methods in the way similar to the Tarantool submodule box.space, like, space[space_id].select(), space[space_id].replace(), and so on.

All the Space class methods listed below work in the following way:

  • A method encodes the corresponding request in the MessagePack format and queues it in the output connection buffer to be sent later by one of Connector’s methods, namely, wait(), waitAll(), or waitAny().
  • A method returns the request ID. To get and read the actual data requested, first you need to get the response object by using the getResponce() method and then decode the data.

Public methods:

template<class T>
rid_t select(const T &key, uint32_t index_id = 0, uint32_t limit = UINT32_MAX, uint32_t offset = 0, IteratorType iterator = EQ)

Searches for a tuple or a set of tuples in the given space. The method works similar to space_object:select() and performs the search against the primary index (index_id = 0) by default. In other words, space[space_id].select() equals to space[space_id].index[0].select().

Параметры:
  • key – value to be matched against the index key.
  • index_id – index ID. Optional. Defaults to 0.
  • limit – maximum number of tuples to select. Optional. Defaults to UINT32_MAX.
  • offset – number of tuples to skip. Optional. Defaults to 0.
  • iterator – the type of iterator. Optional. Defaults to EQ.
Результат:

a request ID
Rtype:

rid_t

Possible errors: none.

Example:

/* Equals to space_object:select({key_value}, {limit = 1}) in Tarantool*/
uint32_t space_id = 512;
int key_value = 5;
uint32_t limit = 1;
auto i = conn.space[space_id];
rid_t select = i.select(std::make_tuple(key_value), index_id, limit, offset, iter);
template<class T>
rid_t replace(const T &tuple)

Inserts a tuple into the given space. If a tuple with the same primary key already exists, replace() replaces the existing tuple with a new one. The method works similar to space_object:replace() / put().

Параметры:tuple – a tuple to insert.
Результат:a request ID
Rtype:rid_t

Possible errors: none.

Example:

/* Equals to space_object:replace(key_value, "111", 1.01) in Tarantool*/
uint32_t space_id = 512;
int key_value = 5;
std::tuple data = std::make_tuple(key_value, "111", 1.01);
rid_t replace = conn.space[space_id].replace(data);
template<class T>
rid_t insert(const T &tuple)

Inserts a tuple into the given space. The method works similar to space_object:insert().

Параметры:tuple – a tuple to insert.
Результат:a request ID
Rtype:rid_t

Possible errors: none.

Example:

/* Equals to space_object:insert(key_value, "112", 2.22) in Tarantool*/
uint32_t space_id = 512;
int key_value = 6;
std::tuple data = std::make_tuple(key_value, "112", 2.22);
rid_t insert = conn.space[space_id].insert(data);
template<class K, class T>
rid_t update(const K &key, const T &tuple, uint32_t index_id = 0)

Updates a tuple in the given space. The method works similar to space_object:update() and searches for the tuple to update against the primary index (index_id = 0) by default. In other words, space[space_id].update() equals to space[space_id].index[0].update().

The tuple parameter specifies an update operation, an identifier of the field to update, and a new field value. The set of available operations and the format of specifying an operation and a field identifier is the same as in Tarantool. Refer to the description of :doc:` </reference/reference_lua/box_space/update>` and example below for details.

Параметры:
  • key – value to be matched against the index key.
  • tuple – parameters for the update operation, namely, operator, field_identifier, value.
  • index_id – index ID. Optional. Defaults to 0.
Результат:

a request ID
Rtype:

rid_t

Possible errors: none.

Example:

/* Equals to space_object:update(key, {{'=', 1, 'update' }, {'+', 2, 12}}) in Tarantool*/
uint32_t space_id = 512;
std::tuple key = std::make_tuple(5);
std::tuple op1 = std::make_tuple("=", 1, "update");
std::tuple op2 = std::make_tuple("+", 2, 12);
rid_t f1 = conn.space[space_id].update(key, std::make_tuple(op1, op2));
template<class T, class O>
rid_t upsert(const T &tuple, const O &ops, uint32_t index_base = 0)

Updates or inserts a tuple in the given space. The method works similar to space_object:upsert().

If there is an existing tuple that matches the key fields of tuple, the request has the same effect as update() and the ops parameter is used. If there is no existing tuple that matches the key fields of tuple, the request has the same effect as insert() and the tuple parameter is used.

Параметры:
  • tuple – a tuple to insert.
  • ops – parameters for the update operation, namely, operator, field_identifier, value.
  • index_base – starting number to count fields in a tuple: 0 or 1. Optional. Defaults to 0.
Результат:

a request ID
Rtype:

rid_t

Possible errors: none.

Example:

/* Equals to space_object:upsert({333, "upsert-insert", 0.0}, {{'=', 1, 'upsert-update'}}) in Tarantool*/
uint32_t space_id = 512;
std::tuple tuple = std::make_tuple(333, "upsert-insert", 0.0);
std::tuple op1 = std::make_tuple("=", 1, "upsert-update");
rid_t f1 = conn.space[space_id].upsert(tuple, std::make_tuple(op1));
template<class T>
rid_t delete_(const T &key, uint32_t index_id = 0)

Deletes a tuple in the given space. The method works similar to space_object:delete() and searches for the tuple to delete against the primary index (index_id = 0) by default. In other words, space[space_id].delete_() equals to space[space_id].index[0].delete_().

Параметры:
  • key – value to be matched against the index key.
  • index_id – index ID. Optional. Defaults to 0.
Результат:

a request ID
Rtype:

rid_t

Possible errors: none.

Example:

/* Equals to space_object:delete(123) in Tarantool*/
uint32_t space_id = 512;
std::tuple key = std::make_tuple(123);
rid_t f1 = conn.space[space_id].delete_(key);

Index class

class Index : Space

Index is a nested class of the Space class. It is a public wrapper to access the data-manipulation methods in the way similar to the Tarantool submodule box.index, like, space[space_id].index[index_id].select() and so on.

All the Index class methods listed below work in the following way:

  • A method encodes the corresponding request in the MessagePack format and queues it in the output connection buffer to be sent later by one of Connector’s methods, namely, wait(), waitAll(), or waitAny().
  • A method returns the request ID that is used to get the response by the getResponce() method. Refer to the getResponce() description to understand the response structure and how to read the requested data.

Public methods:

template<class T>
rid_t select(const T &key, uint32_t limit = UINT32_MAX, uint32_t offset = 0, IteratorType iterator = EQ)

This is an alternative to space.select(). The method searches for a tuple or a set of tuples in the given space against a particular index and works similar to index_object:select().

Параметры:
  • key – value to be matched against the index key.
  • limit – maximum number of tuples to select. Optional. Defaults to UINT32_MAX.
  • offset – number of tuples to skip. Optional. Defaults to 0.
  • iterator – the type of iterator. Optional. Defaults to EQ.
Результат:

a request ID
Rtype:

rid_t

Possible errors: none.

Example:

/* Equals to index_object:select({key}, {limit = 1}) in Tarantool*/
uint32_t space_id = 512;
uint32_t index_id = 1;
int key = 10;
uint32_t limit = 1;
auto i = conn.space[space_id].index[index_id];
rid_t select = i.select(std::make_tuple(key), limit, offset, iter);
template<class K, class T>
rid_t update(const K &key, const T &tuple)

This is an alternative to space.update(). The method updates a tuple in the given space but searches for the tuple against a particular index. The method works similar to index_object:update().

The tuple parameter specifies an update operation, an identifier of the field to update, and a new field value. The set of available operations and the format of specifying an operation and a field identifier is the same as in Tarantool. Refer to the description of :doc:` </reference/reference_lua/box_index/update>` and example below for details.

Параметры:
  • key – value to be matched against the index key.
  • tuple – parameters for the update operation, namely, operator, field_identifier, value.
Результат:

a request ID
Rtype:

rid_t

Possible errors: none.

Example:

/* Equals to index_object:update(key, {{'=', 1, 'update' }, {'+', 2, 12}}) in Tarantool*/
uint32_t space_id = 512;
uint32_t index_id = 1;
std::tuple key = std::make_tuple(10);
std::tuple op1 = std::make_tuple("=", 1, "update");
std::tuple op2 = std::make_tuple("+", 2, 12);
rid_t f1 = conn.space[space_id].index[index_id].update(key, std::make_tuple(op1, op2));
template<class T>
rid_t delete_(const T &key)

This is an alternative to space.delete_(). The method deletes a tuple in the given space but searches for the tuple against a particular index. The method works similar to index_object:delete().

Параметры:key – value to be matched against the index key.
Результат:a request ID
Rtype:rid_t

Possible errors: none.

Example:

/* Equals to index_object:delete(123) in Tarantool*/
uint32_t space_id = 512;
uint32_t index_id = 1;
std::tuple key = std::make_tuple(123);
rid_t f1 = conn.space[space_id].index[index_id].delete_(key);

Community-supported connectors

This section provides information on several community-supported connectors. Note that they may have limited support for new Tarantool features.

For Erlang, use the Erlang tarantool driver.

For R, use the tarantoolr connector.

C#

The most commonly used C# driver is progaudi.tarantool, previously named tarantool-csharp. It is not supplied as part of the Tarantool repository; it must be installed separately. The makers recommend cross-platform installation using Nuget.

To be consistent with the other instructions in this chapter, here is a way to install the driver directly on Ubuntu 16.04.

  1. Install .net core from Microsoft. Follow .net core installation instructions.

Примечание

  1. Create a new console project.

    $ cd ~
$ mkdir progaudi.tarantool.test
$ cd progaudi.tarantool.test
$ dotnet new console

  2. Add progaudi.tarantool reference.

    $ dotnet add package progaudi.tarantool

  3. Change code in Program.cs.

    $ cat <<EOT > Program.cs
using System;
using System.Threading.Tasks;
using ProGaudi.Tarantool.Client;

public class HelloWorld
{
  static public void Main ()
  {
    Test().GetAwaiter().GetResult();
  }
  static async Task Test()
  {
    var box = await Box.Connect("127.0.0.1:3301");
    var schema = box.GetSchema();
    var space = await schema.GetSpace("examples");
    await space.Insert((99999, "BB"));
  }
}
EOT

  4. Build and run your application.

    Before trying to run, check that the server is listening at localhost:3301 and that the space examples exists, as described earlier.

    $ dotnet restore
$ dotnet run

    The program will:

    • connect using an application-specific definition of the space,
    • open a socket connection with the Tarantool server at localhost:3301,
    • send an INSERT request, and — if all is well — end without saying anything.

    If Tarantool is not running on localhost with listen port = 3301, or if user „guest“ does not have authorization to connect, or if the INSERT request fails for any reason, the program will print an error message, among other things (stacktrace, etc).

The example program only shows one request and does not show all that’s necessary for good practice. For that, please see the progaudi.tarantool driver repository.

Node.js

The most commonly used node.js driver is the Node Tarantool driver. It is not supplied as part of the Tarantool repository; it must be installed separately. The most common way to install it is with npm. For example, on Ubuntu, the installation could look like this after npm has been installed:

$ npm install tarantool-driver --global

Here is a complete node.js program that inserts [99999,'BB'] into space[999] via the node.js API. Before trying to run, check that the server instance is listening at localhost:3301 and that the space examples exists, as described earlier. To run, paste the code into a file named example.rs and say node example.rs. The program will connect using an application-specific definition of the space. The program will open a socket connection with the Tarantool instance at localhost:3301, then send an INSERT request, then — if all is well — end after saying «Insert succeeded». If Tarantool is not running on localhost with listen port = 3301, the program will print “Connect failed”. If the „guest“ user does not have authorization to connect, the program will print «Auth failed». If the insert request fails for any reason, for example because the tuple already exists, the program will print «Insert failed».

var TarantoolConnection = require('tarantool-driver');
var conn = new TarantoolConnection({port: 3301});
var insertTuple = [99999, "BB"];
conn.connect().then(function() {
    conn.auth("guest", "").then(function() {
        conn.insert(999, insertTuple).then(function() {
            console.log("Insert succeeded");
            process.exit(0);
    }, function(e) { console.log("Insert failed");  process.exit(1); });
    }, function(e) { console.log("Auth failed");    process.exit(1); });
    }, function(e) { console.log("Connect failed"); process.exit(1); });

The example program only shows one request and does not show all that’s necessary for good practice. For that, please see The node.js driver repository.

Perl

The most commonly used Perl driver is tarantool-perl. It is not supplied as part of the Tarantool repository; it must be installed separately. The most common way to install it is by cloning from GitHub.

To avoid minor warnings that may appear the first time tarantool-perl is installed, start with installing some other modules that tarantool-perl uses, with CPAN, the Comprehensive Perl Archive Network:

$ sudo cpan install AnyEvent
$ sudo cpan install Devel::GlobalDestruction

Then, to install tarantool-perl itself, say:

$ git clone https://github.com/tarantool/tarantool-perl.git tarantool-perl
$ cd tarantool-perl
$ git submodule init
$ git submodule update --recursive
$ perl Makefile.PL
$ make
$ sudo make install

Here is a complete Perl program that inserts [99999,'BB'] into space[999] via the Perl API. Before trying to run, check that the server instance is listening at localhost:3301 and that the space examples exists, as described earlier. To run, paste the code into a file named example.pl and say perl example.pl. The program will connect using an application-specific definition of the space. The program will open a socket connection with the Tarantool instance at localhost:3301, then send an space_object:INSERT request, then — if all is well — end without displaying any messages. If Tarantool is not running on localhost with listen port = 3301, the program will print “Connection refused”.

#!/usr/bin/perl
use DR::Tarantool ':constant', 'tarantool';
use DR::Tarantool ':all';
use DR::Tarantool::MsgPack::SyncClient;

my $tnt = DR::Tarantool::MsgPack::SyncClient->connect(
  host    => '127.0.0.1',                      # look for tarantool on localhost
  port    => 3301,                             # on port 3301
  user    => 'guest',                          # username. for 'guest' we do not also say 'password=>...'

  spaces  => {
    999 => {                                   # definition of space[999] ...
      name => 'examples',                      #   space[999] name = 'examples'
      default_type => 'STR',                   #   space[999] field type is 'STR' if undefined
      fields => [ {                            #   definition of space[999].fields ...
          name => 'field1', type => 'NUM' } ], #     space[999].field[1] name='field1',type='NUM'
      indexes => {                             #   definition of space[999] indexes ...
        0 => {
          name => 'primary', fields => [ 'field1' ] } } } } );

$tnt->insert('examples' => [ 99999, 'BB' ]);

The example program uses field type names „STR“ and „NUM“ instead of „string“ and „unsigned“, due to a temporary Perl limitation.

The example program only shows one request and does not show all that’s necessary for good practice. For that, please see the tarantool-perl repository.

PHP

tarantool-php is the official PHP connector for Tarantool. It is not supplied as part of the Tarantool repository and must be installed separately (see installation instructions in the connector’s README file).

Here is a complete PHP program that inserts [99999,'BB'] into a space named examples via the PHP API.

Before trying to run, check that the server instance is listening at localhost:3301 and that the space examples exists, as described earlier.

To run, paste the code into a file named example.php and say:

$ php -d extension=~/tarantool-php/modules/tarantool.so example.php

The program will open a socket connection with the Tarantool instance at localhost:3301, then send an INSERT request, then – if all is well – print «Insert succeeded».

If the tuple already exists, the program will print «Duplicate key exists in unique index „primary“ in space „examples“».

<?php
$tarantool = new Tarantool('localhost', 3301);

try {
    $tarantool->insert('examples', [99999, 'BB']);
    echo "Insert succeeded\n";
} catch (Exception $e) {
    echo $e->getMessage(), "\n";
}

The example program only shows one request and does not show all that’s necessary for good practice. For that, please see tarantool/tarantool-php project at GitHub.

Besides, there is another community-driven tarantool-php GitHub project which includes an alternative connector written in pure PHP, an object mapper, a queue and other packages.

Справочники

Configuration reference

This topic describes all configuration parameters provided by Tarantool.

Most of the configuration options described in this reference can be applied to a specific instance, replica set, group, or to all instances globally. To do so, you need to define the required option at the specified level.

app

Using Tarantool as an application server, you can run your own Lua applications. In the app section, you can load the application and provide an application configuration in the app.cfg section.

Примечание

app can be defined in any scope.

Примечание

Note that an application specified using app is loaded after application roles specified using the roles option.

app.cfg

A configuration of the application loaded using app.file or app.module.

Example

In the example below, the application is loaded from the myapp.lua file placed next to the YAML configuration file:

app:
  file: 'myapp.lua'
  cfg:
    greeting: 'Hello'

Example on GitHub: application

Совет

The experimental.config.utils.schema built-in module provides an API for managing user-defined configurations of applications (app.cfg) and roles (roles_cfg).


Type: map
Default: nil
Environment variable: TT_APP_CFG
app.file

A path to a Lua file to load an application from.


Type: string
Default: nil
Environment variable: TT_APP_FILE
app.module

A Lua module to load an application from.

Example

The app section can be placed in any configuration scope. As an example use case, you can provide different applications for storages and routers in a sharded cluster:

groups:
  storages:
    app:
      module: storage
      # ...
  routers:
    app:
      module: router
      # ...

Type: string
Default: nil
Environment variable: TT_APP_MODULE

audit_log

Enterprise Edition

Configuring audit_log parameters is available in the Enterprise Edition only.

The audit_log section defines configuration parameters related to audit logging.

Примечание

audit_log can be defined in any scope.

audit_log.extract_key

If set to true, the audit subsystem extracts and prints only the primary key instead of full tuples in DML events (space_insert, space_replace, space_delete). Otherwise, full tuples are logged. The option may be useful in case tuples are big.


Type: boolean
Default: false
Environment variable: TT_AUDIT_LOG_EXTRACT_KEY
audit_log.file

Specify a file for the audit log destination. You can set the file type using the audit_log.to option. If you write logs to a file, Tarantool reopens the audit log at SIGHUP.


Type: string
Default: „var/log/{{ instance_name }}/audit.log“
Environment variable: TT_AUDIT_LOG_FILE
audit_log.filter

Enable logging for a specified subset of audit events. This option accepts the following values:

  • Event names (for example, password_change). For details, see Audit log events.
  • Event groups (for example, audit). For details, see Event groups.

The option contains either one value from Possible values section (see below) or a combination of them.

To enable custom audit log events, specify the custom value in this option.

Example

filter: [ user_create,data_operations,ddl,custom ]

Type: array
Possible values: „all“, „audit“, „auth“, „priv“, „ddl“, „dml“, „data_operations“, „compatibility“, „audit_enable“, „auth_ok“, „auth_fail“, „disconnect“, „user_create“, „user_drop“, „role_create“, „role_drop“, „user_disable“, „user_enable“, „user_grant_rights“, „role_grant_rights“, „role_revoke_rights“, „password_change“, „access_denied“, „eval“, „call“, „space_select“, „space_create“, „space_alter“, „space_drop“, „space_insert“, „space_replace“, „space_delete“, „custom“
Default: „nil“
Environment variable: TT_AUDIT_LOG_FILTER
audit_log.format

Specify a format that is used for the audit log.

Example

If you set the option to plain,

audit_log:
  to: file
  format: plain

the output in the file might look as follows:

2024-01-17T00:12:27.155+0300
4b5a2624-28e5-4b08-83c7-035a0c5a1db9
INFO remote:unix/:(socket)
session_type:console
module:tarantool
user:admin
type:space_create
tag:
description:Create space Bands

Type: string
Possible values: „json“, „csv“, „plain“
Default: „json“
Environment variable: TT_AUDIT_LOG_FORMAT
audit_log.nonblock

Specify the logging behavior if the system is not ready to write. If set to true, Tarantool does not block during logging if the system is non-writable and writes a message instead. Using this value may improve logging performance at the cost of losing some log messages.

Примечание

The option only has an effect if the audit_log.to is set to syslog or pipe.


Type: boolean
Default: false
Environment variable: TT_AUDIT_LOG_NONBLOCK
audit_log.pipe

Specify a pipe for the audit log destination. You can set the pipe type using the audit_log.to option. If log is a program, its pid is stored in the audit.pid field. You need to send it a signal to rotate logs.

Example

This starts the cronolog program when the server starts and sends all audit_log messages to cronolog standard input (stdin).

audit_log:
  to: pipe
  pipe: 'cronolog audit_tarantool.log'

Type: string
Default: box.NULL
Environment variable: TT_AUDIT_LOG_PIPE
audit_log.spaces

The array of space names for which data operation events (space_select, space_insert, space_replace, space_delete) should be logged. The array accepts string values. If set to box.NULL, the data operation events are logged for all spaces.

Example

In the example, only the events of bands and singers spaces are logged:

audit_log:
  spaces: [bands, singers]

Type: array
Default: box.NULL
Environment variable: TT_AUDIT_LOG_SPACES
audit_log.to

Enable audit logging and define the log location. This option accepts the following values:

By default, audit logging is disabled.

Example

The basic audit log configuration might look as follows:

audit_log:
  to: file
  file: 'audit_tarantool.log'
  filter: [ user_create,data_operations,ddl,custom ]
  format: json
  spaces: [ bands ]
  extract_key: true

Type: string
Possible values: „devnull“, „file“, „pipe“, „syslog“
Default: „devnull“
Environment variable: TT_AUDIT_LOG_TO

audit_log.syslog.*

audit_log.syslog.facility

Specify a system logger keyword that tells syslogd where to send the message. You can enable logging to a system logger using the audit_log.to option.

See also: syslog configuration example


Type: string
Possible values: „auth“, „authpriv“, „cron“, „daemon“, „ftp“, „kern“, „lpr“, „mail“, „news“, „security“, „syslog“, „user“, „uucp“, „local0“, „local1“, „local2“, „local3“, „local4“, „local5“, „local6“, „local7“
Default: „local7“
Environment variable: TT_AUDIT_LOG_SYSLOG_FACILITY
audit_log.syslog.identity

Specify an application name to show in logs. You can enable logging to a system logger using the audit_log.to option.

See also: syslog configuration example


Type: string
Default: „tarantool“
Environment variable: TT_AUDIT_LOG_SYSLOG_IDENTITY
audit_log.syslog.server

Set a location for the syslog server. It can be a Unix socket path starting with „unix:“ or an ipv4 port number. You can enable logging to a system logger using the audit_log.to option.

Example

audit_log:
  to: syslog
  syslog:
    server: 'unix:/dev/log'
    facility: 'user'
    identity: 'tarantool_audit'

These options are interpreted as a message for the syslogd program, which runs in the background of any Unix-like platform.

An example of a Tarantool audit log entry in the syslog:

09:32:52 tarantool_audit: {"time": "2024-02-08T09:32:52.190+0300", "uuid": "94454e46-9a0e-493a-bb9f-d59e44a43581", "severity": "INFO", "remote": "unix/:(socket)", "session_type": "console", "module": "tarantool", "user": "admin", "type": "space_create", "tag": "", "description": "Create space bands"}

Предупреждение

Above is an example of writing audit logs to a directory shared with the system logs. Tarantool allows this option, but it is not recommended to do this to avoid difficulties when working with audit logs. System and audit logs should be written separately. To do this, create separate paths and specify them.


Type: string
Default: box.NULL
Environment variable: TT_AUDIT_LOG_SYSLOG_SERVER

compat

The compat section defines values of the compat module options.

Примечание

compat can be defined in any scope.

compat.binary_data_decoding

Define how to store binary data fields in Lua after decoding:

  • new: as varbinary objects
  • old: as plain strings

See also: Decoding binary objects


Type: string
Possible values: „new“, „old“
Default: „new“
Environment variable: TT_COMPAT_BINARY_DATA_DECODING
compat.box_cfg_replication_sync_timeout

Set a default replication sync timeout:

  • new: 0
  • old: 300 seconds

Важно

This value is set during the initial box.cfg{} call and cannot be changed later.

See also: Default value for replication_sync_timeout


Type: string
Possible values: „new“, „old“
Default: „new“
Environment variable: TT_COMPAT_BOX_CFG_REPLICATION_SYNC_TIMEOUT
compat.box_error_serialize_verbose

Since: 3.1.0

Set the verbosity of error objects serialization:

  • new: serialize the error message together with other potentially useful fields
  • old: serialize only the error message

Type: string
Possible values: „new“, „old“
Default: „old“
Environment variable: TT_COMPAT_BOX_ERROR_SERIALIZE_VERBOSE
compat.box_error_unpack_type_and_code

Since: 3.1.0

Whether to show error fields in box.error.unpack():

  • new: do not show base_type and custom_type fields; do not show the code field if it is 0. Note that base_type is still accessible for an error object.
  • old: show all fields

Type: string
Possible values: „new“, „old“
Default: „old“
Environment variable: TT_COMPAT_BOX_ERROR_UNPACK_TYPE_AND_CODE
compat.box_info_cluster_meaning

Define the behavior of box.info.cluster:

  • new: show the entire cluster
  • old:: show the current replica set

See also: Meaning of box.info.cluster


Type: string
Possible values: „new“, „old“
Default: „new“
Environment variable: TT_COMPAT_BOX_INFO_CLUSTER_MEANING
compat.box_session_push_deprecation

Whether to raise errors on attempts to call the deprecated function box.session.push:

  • new: raise an error
  • old: do not raise an error

Type: string
Possible values: „new“, „old“
Default: „old“
Environment variable: TT_COMPAT_BOX_SESSION_PUSH_DEPRECATION
compat.box_space_execute_priv

Whether the execute privilege can be granted on spaces:

  • new: an error is raised
  • old: the privilege can be granted with no actual effect

Type: string
Possible values: „new“, „old“
Default: „new“
Environment variable: TT_COMPAT_BOX_SPACE_EXECUTE_PRIV
compat.box_space_max

Set the maximum space identifier (box.schema.SPACE_MAX):

  • new: 2147483646
  • old: 2147483647

The limit was decremented because the old max value is used as an error indicator in the box C API.


Type: string
Possible values: „new“, „old“
Default: „new“
Environment variable: TT_COMPAT_BOX_SPACE_MAX
compat.box_tuple_extension

Controls IPROTO_FEATURE_CALL_RET_TUPLE_EXTENSION and IPROTO_FEATURE_CALL_ARG_TUPLE_EXTENSION feature bits that define tuple encoding in iproto call and eval requests.

  • new: tuples with formats are encoded as MP_TUPLE
  • old: tuples with formats are encoded as MP_ARRAY

Type: string
Possible values: „new“, „old“
Default: „new“
Environment variable: TT_COMPAT_BOX_TUPLE_EXTENSION
compat.box_tuple_new_vararg

Controls how box.tuple.new interprets an argument list:

  • new: as a value with a tuple format
  • old: as an array of tuple fields

Type: string
Possible values: „new“, „old“
Default: „new“
Environment variable: TT_COMPAT_BOX_TUPLE_NEW_VARARG
compat.c_func_iproto_multireturn

Controls wrapping of multiple results of a stored C function when returning them via iproto:

  • new: return without wrapping (consistently with a local call via box.func)
  • old: wrap results into a MessagePack array

Type: string
Possible values: „new“, „old“
Default: „new“
Environment variable: TT_COMPAT_C_FUNC_IPROTO_MULTIRETURN
compat.fiber_channel_close_mode

Define the behavior of fiber channels after closing:

  • new: mark the channel read-only
  • old: destroy the channel object

See also: Fiber channel close mode


Type: string
Possible values: „new“, „old“
Default: „new“
Environment variable: TT_COMPAT_FIBER_CHANNEL_CLOSE_MODE
compat.fiber_slice_default

Define the maximum fiber execution time without a yield:

  • new: {warn = 0.5, err = 1.0}
  • old: infinity (no warnings or errors raised).

See also: Default value for max fiber slice


Type: string
Possible values: „new“, „old“
Default: „new“
Environment variable: TT_COMPAT_FIBER_SLICE_DEFAULT
compat.json_escape_forward_slash

Whether to escape the forward slash symbol „/“ using a backslash in a json.encode() result:

  • new: do not escape the forward slash
  • old: escape the forward slash

See also: JSON encode escape forward slash


Type: string
Possible values: „new“, „old“
Default: „new“
Environment variable: TT_COMPAT_JSON_ESCAPE_FORWARD_SLASH
compat.sql_priv

Whether to enable access checks for SQL requests over iproto:

  • new: check the user’s access permissions
  • old: allow any user to execute SQL over iproto

Type: string
Possible values: „new“, „old“
Default: „new“
Environment variable: TT_COMPAT_SQL_PRIV
compat.sql_seq_scan_default

Controls the default value of the sql_seq_scan session setting:

  • new: false
  • old: true

See also: Default value for sql_seq_scan session setting


Type: string
Possible values: „new“, „old“
Default: „new“
Environment variable: TT_COMPAT_SQL_SEQ_SCAN_DEFAULT
compat.yaml_pretty_multiline

Whether to encode in block scalar style all multiline strings or ones containing the \n\n substring:

  • new: all multiline strings
  • old: only strings containing the \n\n substring

See also: Lua-YAML prettier multiline output


Type: string
Possible values: „new“, „old“
Default: „new“
Environment variable: TT_COMPAT_YAML_PRETTY_MULTILINE

conditional

The conditional section defines the configuration parts that apply to instances that meet certain conditions.

Примечание

conditional can be defined in the global scope only.

conditional.if

Specify a conditional section of the configuration. The configuration options defined inside a conditional.if section apply only to instances on which the specified condition is true.

Conditions can include one variable – tarantool_version: a three-number Tarantool version running on the instance, for example, 3.1.0. It compares to version literal values that include three numbers separated by periods (x.y.z).

The following operators are available in conditions:

  • comparison: >, <, >=, <=, ==, !=
  • logical operators || (OR) and && (AND)
  • parentheses ()

Example:

In this example, different configuration parts apply to instances running Tarantool versions above and below 3.1.0:

  • On versions less than 3.1.0, the upgraded label is set to false.
  • On versions 3.1.0 or newer, the upgraded label is set to true. Additionally, new compat options are defined. These options were introduced in version 3.1.0, so on older versions they would cause an error.
conditional:
  - if: tarantool_version < 3.1.0
    labels:
      upgraded: 'false'
  - if: tarantool_version >= 3.1.0
    labels:
      upgraded: 'true'
    compat:
      box_error_serialize_verbose: 'new'
      box_error_unpack_type_and_code: 'new'

See also: Conditional configuration sections

config

The config section defines various parameters related to centralized configuration.

Примечание

config can be defined in the global scope only.

config.reload

Specify how the configuration is reloaded. This option accepts the following values:

  • auto: configuration is reloaded automatically when it is changed.
  • manual: configuration should be reloaded manually. In this case, you can reload the configuration in the application code using config:reload().

See also: Reloading configuration


Type: string
Possible values: „auto“, „manual“
Default: „auto“
Environment variable: TT_CONFIG_RELOAD

config.context.*

This section describes options related to loading configuration settings from external storage such as external files or environment variables.

config.context

Specify how to load settings from external storage. For example, this option can be used to load passwords from safe storage. You can find examples in the Loading secrets from safe storage section.


Type: map
Default: nil
Environment variable: TT_CONFIG_CONTEXT
config.context.<name>

The name of an entity that identifies a configuration value to load.

config.context.<name>.env

The name of an environment variable to load a configuration value from. To load a configuration value from an environment variable, set config.context.<name>.from to env.

Example

In this example, passwords are loaded from the DBADMIN_PASSWORD and SAMPLEUSER_PASSWORD environment variables:

config:
  context:
    dbadmin_password:
      from: env
      env: DBADMIN_PASSWORD
    sampleuser_password:
      from: env
      env: SAMPLEUSER_PASSWORD

See also: Loading secrets from safe storage

config.context.<name>.from

The type of storage to load a configuration value from. There are the following storage types:

  • file: load a configuration value from a file. In this case, you need to specify the path to the file using config.context.<name>.file.
  • env: load a configuration value from an environment variable. In this case, specify the environment variable name using config.context.<name>.env.
config.context.<name>.file

The path to a file to load a configuration value from. To load a configuration value from a file, set config.context.<name>.from to file.

Example

In this example, passwords are loaded from the dbadmin_password.txt and sampleuser_password.txt files:

config:
  context:
    dbadmin_password:
      from: file
      file: secrets/dbadmin_password.txt
      rstrip: true
    sampleuser_password:
      from: file
      file: secrets/sampleuser_password.txt
      rstrip: true

See also: Loading secrets from safe storage

config.context.<name>.rstrip

(Optional) Whether to strip whitespace characters and newlines from the end of data.

config.etcd.*

Enterprise Edition

Centralized configuration storages are supported by the Enterprise Edition only.

This section describes options related to providing connection settings to a centralized etcd-based storage. If replication.failover is set to supervised, Tarantool also uses etcd to maintain the state of failover coordinators.

Примечание

Note that a centralized cluster configuration cannot contain the config.etcd section.

config.etcd.endpoints

The list of endpoints used to access an etcd server.

See also: Configuring connection to an etcd storage


Type: array
Default: nil
Environment variable: TT_CONFIG_ETCD_ENDPOINTS
config.etcd.prefix

A key prefix used to search a configuration on an etcd server. Tarantool searches keys by the following path: <prefix>/config/*. Note that <prefix> should start with a slash (/).

See also: Configuring connection to an etcd storage


Type: string
Default: nil
Environment variable: TT_CONFIG_ETCD_PREFIX
config.etcd.username

A username used for authentication.

See also: Configuring connection to an etcd storage


Type: string
Default: nil
Environment variable: TT_CONFIG_ETCD_USERNAME
config.etcd.password

A password used for authentication.

See also: Configuring connection to an etcd storage


Type: string
Default: nil
Environment variable: TT_CONFIG_ETCD_PASSWORD
config.etcd.ssl.ca_file

A path to a trusted certificate authorities (CA) file.


Type: string
Default: nil
Environment variable: TT_CONFIG_ETCD_SSL_CA_FILE
config.etcd.ssl.ca_path

A path to a directory holding certificates to verify the peer with.


Type: string
Default: nil
Environment variable: TT_CONFIG_ETCD_SSL_CA_PATH
config.etcd.ssl.ssl_cert

Since: 3.2.0

A path to an SSL certificate file.


Type: string
Default: nil
Environment variable: TT_CONFIG_ETCD_SSL_SSL_CERT
config.etcd.ssl.ssl_key

A path to a private SSL key file.


Type: string
Default: nil
Environment variable: TT_CONFIG_ETCD_SSL_SSL_KEY
config.etcd.ssl.verify_host

Enable verification of the certificate’s name (CN) against the specified host.


Type: boolean
Default: nil
Environment variable: TT_CONFIG_ETCD_SSL_VERIFY_HOST
config.etcd.ssl.verify_peer

Enable verification of the peer’s SSL certificate.


Type: boolean
Default: nil
Environment variable: TT_CONFIG_ETCD_SSL_VERIFY_PEER
config.etcd.http.request.timeout

A time period required to process an HTTP request to an etcd server: from sending a request to receiving a response.

See also: Configuring connection to an etcd storage


Type: number
Default: nil
Environment variable: TT_CONFIG_ETCD_HTTP_REQUEST_TIMEOUT
config.etcd.http.request.unix_socket

A Unix domain socket used to connect to an etcd server.


Type: string
Default: nil
Environment variable: TT_CONFIG_ETCD_HTTP_REQUEST_UNIX_SOCKET
config.etcd.watchers.reconnect_max_attempts

Since: 3.1.0

The maximum number of attempts to reconnect to an etcd server in case of connection failure.


Type: integer
Default: nil
Environment variable: TT_CONFIG_ETCD_WATCHERS_RECONNECT_MAX_ATTEMPTS
config.etcd.watchers.reconnect_timeout

Since: 3.1.0

The timeout (in seconds) between attempts to reconnect to an etcd server in case of connection failure.


Type: number
Default: nil
Environment variable: TT_CONFIG_ETCD_WATCHERS_RECONNECT_TIMEOUT

config.storage.*

Enterprise Edition

Centralized configuration storages are supported by the Enterprise Edition only.

This section describes options related to providing connection settings to a centralized Tarantool-based storage.

Примечание

Note that a centralized cluster configuration cannot contain the config.storage section.

config.storage.endpoints

An array of endpoints used to access a configuration storage. Each endpoint can include the following fields:

  • uri: a URI of the configuration storage’s instance.
  • login: a username used to connect to the instance.
  • password: a password used for authentication.
  • params: SSL parameters required for encrypted connections (<uri>.params.*).

See also: Configuring connection to a Tarantool storage


Type: array
Default: nil
Environment variable: TT_CONFIG_STORAGE_ENDPOINTS
config.storage.prefix

A key prefix used to search a configuration in a centralized configuration storage. Tarantool searches keys by the following path: <prefix>/config/*. Note that <prefix> should start with a slash (/).

See also: Configuring connection to a Tarantool storage


Type: string
Default: nil
Environment variable: TT_CONFIG_STORAGE_PREFIX
config.storage.reconnect_after

A number of seconds to wait before reconnecting to a configuration storage.


Type: number
Default: 3
Environment variable: TT_CONFIG_STORAGE_RECONNECT_AFTER
config.storage.timeout

The interval (in seconds) to perform the status check of a configuration storage.

See also: Configuring connection to a Tarantool storage


Type: number
Default: 3
Environment variable: TT_CONFIG_STORAGE_TIMEOUT

console

Configure the administrative console. A client to the console is tt connect.

Примечание

console can be defined in any scope.

console.enabled

Whether to listen on the Unix socket provided in the console.socket option.

If the option is set to false, the administrative console is disabled.


Type: boolean
Default: true
Environment variable: TT_CONSOLE_ENABLED
console.socket

The Unix socket for the administrative console.

Mind the following nuances:

  • Only a Unix domain socket is allowed. A TCP socket can’t be configured this way.
  • console.socket is a file path, without any unix: or unix/: prefixes.
  • If the file path is a relative path, it is interpreted relative to process.work_dir.

Type: string
Default: „var/run/{{ instance_name }}/tarantool.control“
Environment variable: TT_CONSOLE_SOCKET

credentials

The credentials section allows you to create users and grant them the specified privileges. Learn more in Credentials.

Примечание

credentials can be defined in any scope.

credentials.roles.*

credentials.roles

An array of roles that can be granted to users or other roles.

Example

In the example below, the writers_space_reader role gets privileges to select data in the writers space:

roles:
  writers_space_reader:
    privileges:
    - permissions: [ read ]
      spaces: [ writers ]

See also: Managing users and roles


Type: map
Default: nil
Environment variable: TT_CREDENTIALS_ROLES
credentials.roles.<role_name>.roles

An array of roles granted to this role.

credentials.roles.<role_name>.privileges

An array of privileges granted to this role.

See <user_or_role_name>.privileges.*.

credentials.users.*

credentials.users

An array of users.

Example

In this example, sampleuser gets the following privileges:

  • Privileges granted to the writers_space_reader role.
  • Privileges to select and modify data in the books space.
sampleuser:
  password: '123456'
  roles: [ writers_space_reader ]
  privileges:
  - permissions: [ read, write ]
    spaces: [ books ]

See also: Managing users and roles


Type: map
Default: nil
Environment variable: TT_CREDENTIALS_USERS
credentials.users.<username>.password

A user’s password.

Example

In the example below, a password for the dbadmin user is set:

credentials:
  users:
    dbadmin:
      password: 'T0p_Secret_P@$$w0rd'

See also: Loading secrets from safe storage

credentials.users.<username>.roles

An array of roles granted to this user.

credentials.users.<username>.privileges

An array of privileges granted to this user.

See <user_or_role_name>.privileges.*.

<user_or_role_name>.privileges.*

<user_or_role_name>.privileges

Privileges that can be granted to a user or role using the following options:

<user_or_role_name>.privileges.permissions

Permissions assigned to this user or a user with this role.

Example

In this example, sampleuser gets privileges to select and modify data in the books space:

sampleuser:
  password: '123456'
  roles: [ writers_space_reader ]
  privileges:
  - permissions: [ read, write ]
    spaces: [ books ]

See also: Managing users and roles

<user_or_role_name>.privileges.spaces

Spaces to which this user or a user with this role gets the specified permissions.

Example

In this example, sampleuser gets privileges to select and modify data in the books space:

sampleuser:
  password: '123456'
  roles: [ writers_space_reader ]
  privileges:
  - permissions: [ read, write ]
    spaces: [ books ]

See also: Managing users and roles

<user_or_role_name>.privileges.functions

Functions to which this user or a user with this role gets the specified permissions.

<user_or_role_name>.privileges.sequences

Sequences to which this user or a user with this role gets the specified permissions.

<user_or_role_name>.privileges.lua_eval

Whether this user or a user with this role can execute arbitrary Lua code.

<user_or_role_name>.privileges.lua_call

Whether this user or a user with this role can call any global user-defined Lua function.

<user_or_role_name>.privileges.sql

Whether this user or a user with this role can execute an arbitrary SQL expression.

database

The database section defines database-specific configuration parameters, such as an instance’s read-write mode or transaction isolation level.

Примечание

database can be defined in any scope.

database.hot_standby

Whether to start the server in the hot standby mode. This mode can be used to provide failover without replication.

Suppose there are two cluster applications. Each cluster has one instance with the same configuration:

groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            database:
              hot_standby: true
            wal:
              dir: /tmp/wals
            snapshot:
              dir: /tmp/snapshots
            iproto:
              listen:
              - uri: '127.0.0.1:3301'

In particular, both instances use the same directory for storing write-ahead logs and snapshots.

When you start both cluster applications on the same machine, the instance from the first one will be the primary instance and the second will be the standby instance. In the logs of the second cluster instance, you should see a notification:

main/104/interactive I> Entering hot standby mode

This means that the standby instance is ready to take over if the primary instance goes down. The standby instance initializes and tries to take a lock on a directory for storing write-ahead logs but fails because the primary instance has made a lock on this directory.

If the primary instance goes down for any reason, the lock is released. In this case, the standby instance succeeds in taking the lock and becomes the primary instance.

database.hot_standby has no effect:

  • If wal.mode is set to none.
  • If wal.dir_rescan_delay is set to a large value on macOS or FreeBSD. On these platforms, the hot standby mode is designed so that the loop repeats every wal.dir_rescan_delay seconds.
  • For spaces created with engine set to vinyl.

Examples on GitHub: hot_standby_1, hot_standby_2


Type: boolean
Default: false
Environment variable: TT_DATABASE_HOT_STANDBY
database.instance_uuid

An instance UUID.

By default, instance UUIDs are generated automatically. database.instance_uuid can be used to specify an instance identifier manually.

UUIDs should follow these rules:

  • The values must be true unique identifiers, not shared by other instances or replica sets within the common infrastructure.
  • The values must be used consistently, not changed after the initial setup. The initial values are stored in snapshot files and are checked whenever the system is restarted.
  • The values must comply with RFC 4122. The nil UUID is not allowed.

See also: database.replicaset_uuid


Type: string
Default: box.NULL
Environment variable: TT_DATABASE_INSTANCE_UUID
database.mode

An instance’s operating mode. This option is in effect if replication.failover is set to off.

The following modes are available:

  • rw: an instance is in read-write mode.
  • ro: an instance is in read-only mode.

If not specified explicitly, the default value depends on the number of instances in a replica set. For a single instance, the rw mode is used, while for multiple instances, the ro mode is used.

Example

You can set the database.mode option to rw on all instances in a replica set to make a master-master configuration. In this case, replication.failover should be set to off.

credentials:
  users:
    replicator:
      password: 'topsecret'
      roles: [replication]

iproto:
  advertise:
    peer:
      login: replicator

replication:
  failover: off

groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            database:
              mode: rw
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
          instance002:
            database:
              mode: rw
            iproto:
              listen:
              - uri: '127.0.0.1:3302'

# Load sample data
app:
  file: 'myapp.lua'

Type: string
Default: box.NULL (the actual default value depends on the number of instances in a replica set)
Environment variable: TT_DATABASE_MODE
database.replicaset_uuid

A replica set UUID.

By default, replica set UUIDs are generated automatically. database.replicaset_uuid can be used to specify a replica set identifier manually.

See also: database.instance_uuid


Type: string
Default: box.NULL
Environment variable: TT_DATABASE_REPLICASET_UUID
database.txn_isolation

A transaction isolation level.


Type: string
Default: best-effort
Possible values: best-effort, read-committed, read-confirmed
Environment variable: TT_DATABASE_TXN_ISOLATION
database.txn_timeout

A timeout (in seconds) after which the transaction is rolled back.

See also: box.begin()


Type: number
Default: 3153600000 (~100 years)
Environment variable: TT_DATABASE_TXN_TIMEOUT
database.use_mvcc_engine

Whether the transactional manager is enabled.


Type: boolean
Default: false
Environment variable: TT_DATABASE_USE_MVCC_ENGINE

failover

The failover section defines parameters related to a supervised failover.

Примечание

failover can be defined in the global scope only.

failover.call_timeout

Since: 3.1.0

A call timeout (in seconds) for monitoring and failover requests to an instance.

Type: number
Default: 1
Environment variable: TT_FAILOVER_CALL_TIMEOUT
failover.connect_timeout

Since: 3.1.0

A connection timeout (in seconds) for monitoring and failover requests to an instance.

Type: number
Default: 1
Environment variable: TT_FAILOVER_CONNECT_TIMEOUT
failover.lease_interval

Since: 3.1.0

A time interval (in seconds) that specifies how long an instance should be a leader without renew requests from a coordinator. When this interval expires, the leader switches to read-only mode. This action is performed by the instance itself and works even if there is no connectivity between the instance and the coordinator.

Type: number
Default: 30
Environment variable: TT_FAILOVER_LEASE_INTERVAL
failover.probe_interval

Since: 3.1.0

A time interval (in seconds) that specifies how often a monitoring service of the failover coordinator polls an instance for its status.

Type: number
Default: 10
Environment variable: TT_FAILOVER_PROBE_INTERVAL
failover.renew_interval

Since: 3.1.0

A time interval (in seconds) that specifies how often a failover coordinator sends read-write deadline renewals.

Type: number
Default: 10
Environment variable: TT_FAILOVER_RENEW_INTERVAL

failover.stateboard.*

failover.stateboard.* options define configuration parameters related to maintaining the state of failover coordinators in a remote etcd-based storage.

See also: Active and passive coordinators

failover.stateboard.keepalive_interval

Since: 3.1.0

A time interval (in seconds) that specifies how long a transient state information is stored and how quickly a lock expires.

Примечание

failover.stateboard.keepalive_interval should be smaller than failover.lease_interval. Otherwise, switching of a coordinator causes a replica set leader to go to read-only mode for some time.

Type: number
Default: 10
Environment variable: TT_FAILOVER_STATEBOARD_KEEPALIVE_INTERVAL
failover.stateboard.renew_interval

Since: 3.1.0

A time interval (in seconds) that specifies how often a failover coordinator writes its state information to etcd. This option also determines the frequency at which an active coordinator reads new commands from etcd.

Type: number
Default: 2
Environment variable: TT_FAILOVER_STATEBOARD_RENEW_INTERVAL

feedback

The feedback section describes configuration parameters for sending information about a running Tarantool instance to the specified feedback server.

Примечание

feedback can be defined in any scope.

feedback.crashinfo

Whether to send crash information in the case of an instance failure. This information includes:

  • General information from the uname output.
  • Build information.
  • The crash reason.
  • The stack trace.

To turn off sending crash information, set this option to false.


Type: boolean
Default: true
Environment variable: TT_FEEDBACK_CRASHINFO
feedback.enabled

Whether to send information about a running instance to the feedback server. To turn off sending feedback, set this option to false.


Type: boolean
Default: true
Environment variable: TT_FEEDBACK_ENABLED
feedback.host

The address to which information is sent.


Type: string
Default: https://feedback.tarantool.io
Environment variable: TT_FEEDBACK_HOST
feedback.interval

The interval (in seconds) of sending information.


Type: number
Default: 3600
Environment variable: TT_FEEDBACK_INTERVAL
feedback.metrics_collect_interval

The interval (in seconds) for collecting metrics.


Type: number
Default: 60
Environment variable: TT_FEEDBACK_METRICS_COLLECT_INTERVAL
feedback.metrics_limit

The maximum size of memory (in bytes) used to store metrics before sending them to the feedback server. If the size of collected metrics exceeds this value, earlier metrics are dropped.


Type: integer
Default: 1024 * 1024 (1048576)
Environment variable: TT_FEEDBACK_METRICS_LIMIT
feedback.send_metrics

Whether to send metrics to the feedback server. Note that all collected metrics are dropped after sending them to the feedback server.


Type: boolean
Default: true
Environment variable: TT_FEEDBACK_SEND_METRICS

fiber

The fiber section describes options related to configuring fibers, yields, and cooperative multitasking.

Примечание

fiber can be defined in any scope.

fiber.io_collect_interval

The time period (in seconds) a fiber sleeps between iterations of the event loop.

fiber.io_collect_interval can be used to reduce CPU load in deployments where the number of client connections is large, but requests are not so frequent (for example, each connection issues just a handful of requests per second).


Type: number
Default: box.NULL
Environment variable: TT_FIBER_IO_COLLECT_INTERVAL
fiber.too_long_threshold

If processing a request takes longer than the given period (in seconds), the fiber warns about it in the log.

fiber.too_long_threshold has effect only if log.level is greater than or equal to 4 (warn).


Type: number
Default: 0.5
Environment variable: TT_FIBER_TOO_LONG_THRESHOLD
fiber.worker_pool_threads

The maximum number of threads to use during execution of certain internal processes (for example, socket.getaddrinfo() and coio_call()).


Type: number
Default: 4
Environment variable: TT_FIBER_WORKER_POOL_THREADS

fiber.slice.*

This section describes options related to configuring time periods for fiber slices. See fiber.set_max_slice for details and examples.

fiber.slice.warn

Set a time period (in seconds) that specifies the warning slice.


Type: number
Default: 0.5
Environment variable: TT_FIBER_SLICE_WARN
fiber.slice.err

Set a time period (in seconds) that specifies the error slice.


Type: number
Default: 1
Environment variable: TT_FIBER_SLICE_ERR

fiber.top.*

This section describes options related to configuring the fiber.top() function, normally used for debug purposes. fiber.top() shows all alive fibers and their CPU consumption.

fiber.top.enabled

Enable or disable the fiber.top() function.

Enabling fiber.top() slows down fiber switching by about 15%, so it is disabled by default.


Type: boolean
Default: false
Environment variable: TT_FIBER_TOP_ENABLED

flightrec

Enterprise Edition

Configuring flightrec parameters is available in the Enterprise Edition only.

The flightrec section describes options related to the flight recorder configuration.

Примечание

flightrec can be defined in any scope.

flightrec.enabled

Enable the flight recorder.


Type: boolean
Default: false
Environment variable: TT_FLIGHTREC_ENABLED
flightrec.logs_size

Specify the size (in bytes) of the log storage. You can set this option to 0 to disable the log storage.


Type: integer
Default: 10485760
Environment variable: TT_FLIGHTREC_LOGS_SIZE
flightrec.logs_max_msg_size

Specify the maximum size (in bytes) of the log message. The log message is truncated if its size exceeds this limit.


Type: integer
Default: 4096
Maximum: 16384
Environment variable: TT_FLIGHTREC_LOGS_MAX_MSG_SIZE
flightrec.logs_log_level

Specify the level of detail the log has. The default value is 6 (VERBOSE). You can learn more about log levels from the log_level option description. Note that the flightrec.logs_log_level value might differ from log_level.


Type: integer
Default: 6
Environment variable: TT_FLIGHTREC_LOGS_LOG_LEVEL
flightrec.metrics_period

Specify the time period (in seconds) that defines how long metrics are stored from the moment of dump. So, this value defines how much historical metrics data is collected up to the moment of crash. The frequency of metric dumps is defined by flightrec.metrics_interval.


Type: integer
Default: 180
Environment variable: TT_FLIGHTREC_METRICS_PERIOD
flightrec.metrics_interval

Specify the time interval (in seconds) that defines the frequency of dumping metrics. This value shouldn’t exceed flightrec.metrics_period.


Type: number
Default: 1.0
Minimum: 0.001
Environment variable: TT_FLIGHTREC_METRICS_INTERVAL

Примечание

Given that the average size of a metrics entry is 2 kB, you can estimate the size of the metrics storage as follows:

(flightrec_metrics_period / flightrec_metrics_interval) * 2 kB
flightrec.requests_size

Specify the size (in bytes) of storage for the request and response data. You can set this parameter to 0 to disable a storage of requests and responses.


Type: integer
Default: 10485760
Environment variable: TT_FLIGHTREC_REQUESTS_SIZE
flightrec.requests_max_req_size

Specify the maximum size (in bytes) of a request entry. A request entry is truncated if this size is exceeded.


Type: integer
Default: 16384
Environment variable: TT_FLIGHTREC_REQUESTS_MAX_REQ_SIZE
flightrec.requests_max_res_size

Specify the maximum size (in bytes) of a response entry. A response entry is truncated if this size is exceeded.


Type: integer
Default: 16384
Environment variable: TT_FLIGHTREC_REQUESTS_MAX_RES_SIZE

iproto

The iproto section is used to configure parameters related to communicating to and between cluster instances.

Примечание

iproto can be defined in any scope.

iproto.listen

An array of URIs used to listen for incoming requests. If required, you can enable SSL for specific URIs by providing additional parameters (<uri>.params.*).

Note that a URI value can’t contain parameters, a login, or a password.

Example

In the example below, iproto.listen is set explicitly for each instance in a cluster:

groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
          instance002:
            iproto:
              listen:
              - uri: '127.0.0.1:3302'
          instance003:
            iproto:
              listen:
              - uri: '127.0.0.1:3303'

See also: Connections


Type: array
Default: nil
Environment variable: TT_IPROTO_LISTEN
iproto.net_msg_max

To handle messages, Tarantool allocates fibers. To prevent fiber overhead from affecting the whole system, Tarantool restricts how many messages the fibers handle, so that some pending requests are blocked.

  • On powerful systems, increase net_msg_max, and the scheduler starts processing pending requests immediately.
  • On weaker systems, decrease net_msg_max, and the overhead may decrease. However, this may take some time because the scheduler must wait until already-running requests finish.

When net_msg_max is reached, Tarantool suspends processing of incoming packages until it has processed earlier messages. This is not a direct restriction of the number of fibers that handle network messages, rather it is a system-wide restriction of channel bandwidth. This in turn restricts the number of incoming network messages that the transaction processor thread handles, and therefore indirectly affects the fibers that handle network messages.

Примечание

The number of fibers is smaller than the number of messages because messages can be released as soon as they are delivered, while incoming requests might not be processed until some time after delivery.


Type: integer
Default: 768
Environment variable: TT_IPROTO_NET_MSG_MAX
iproto.readahead

The size of the read-ahead buffer associated with a client connection. The larger the buffer, the more memory an active connection consumes, and the more requests can be read from the operating system buffer in a single system call.

The recommendation is to make sure that the buffer can contain at least a few dozen requests. Therefore, if a typical tuple in a request is large, e.g. a few kilobytes or even megabytes, the read-ahead buffer size should be increased. If batched request processing is not used, it’s prudent to leave this setting at its default.


Type: integer
Default: 16320
Environment variable: TT_IPROTO_READAHEAD
iproto.threads

The number of network threads. There can be unusual workloads where the network thread is 100% loaded and the transaction processor thread is not, so the network thread is a bottleneck. In that case, set iproto_threads to 2 or more. The operating system kernel determines which connection goes to which thread.


Type: integer
Default: 1
Environment variable: TT_IPROTO_THREADS

iproto.advertise.*

iproto.advertise.client

A URI used to advertise the current instance to clients.

The iproto.advertise.client option accepts a URI in the following formats:

  • An address: host:port.
  • A Unix domain socket: unix/:.

Note that this option doesn’t allow to set a username and password. If a remote client needs this information, it should be delivered outside of the cluster configuration.

Примечание

The host value cannot be 0.0.0.0/[::] and the port value cannot be 0.


Type: string
Default: box.NULL
Environment variable: TT_IPROTO_ADVERTISE_CLIENT
iproto.advertise.peer

Settings used to advertise the current instance to other cluster members. The format of these settings is described in iproto.advertise.<peer_or_sharding>.*.

Example

In the example below, the following configuration options are specified:

  • In the credentials section, the replicator user with the replication role is created.
  • iproto.advertise.peer specifies that other instances should connect to an address defined in iproto.listen using the replicator user.
credentials:
  users:
    replicator:
      password: 'topsecret'
      roles: [replication]

iproto:
  advertise:
    peer:
      login: replicator

replication:
  failover: election

groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
          instance002:
            iproto:
              listen:
              - uri: '127.0.0.1:3302'
          instance003:
            iproto:
              listen:
              - uri: '127.0.0.1:3303'

Type: map
Environment variable: see iproto.advertise.<peer_or_sharding>.*
iproto.advertise.sharding

Settings used to advertise the current instance to a router and rebalancer. The format of these settings is described in iproto.advertise.<peer_or_sharding>.*.

Примечание

If iproto.advertise.sharding is not specified, advertise settings from iproto.advertise.peer are used.

Example

In the example below, the following configuration options are specified:

  • In the credentials section, the replicator and storage users are created.
  • iproto.advertise.peer specifies that other instances should connect to an address defined in iproto.listen with the replicator user.
  • iproto.advertise.sharding specifies that a router should connect to storages using an address defined in iproto.listen with the storage user.
credentials:
  users:
    replicator:
      password: 'topsecret'
      roles: [replication]
    storage:
      password: 'secret'
      roles: [sharding]

iproto:
  advertise:
    peer:
      login: replicator
    sharding:
      login: storage

Type: map
Environment variable: see iproto.advertise.<peer_or_sharding>.*

iproto.advertise.<peer_or_sharding>.*

iproto.advertise.<peer_or_sharding>.uri

(Optional) A URI used to advertise the current instance. By default, the URI defined in iproto.listen is used to advertise the current instance.

Примечание

The host value cannot be 0.0.0.0/[::] and the port value cannot be 0.


Type: string
Default: nil
Environment variable: TT_IPROTO_ADVERTISE_PEER_URI, TT_IPROTO_ADVERTISE_SHARDING_URI
iproto.advertise.<peer_or_sharding>.login

(Optional) A username used to connect to the current instance. If a username is not set, the guest user is used.


Type: string
Default: nil
Environment variable: TT_IPROTO_ADVERTISE_PEER_LOGIN, TT_IPROTO_ADVERTISE_SHARDING_LOGIN
iproto.advertise.<peer_or_sharding>.password

(Optional) A password for the specified user. If a login is specified but a password is missing, it is taken from the user’s credentials.


Type: string
Default: nil
Environment variable: TT_IPROTO_ADVERTISE_PEER_PASSWORD, TT_IPROTO_ADVERTISE_SHARDING_PASSWORD
iproto.advertise.<peer_or_sharding>.params

(Optional) URI parameters (<uri>.params.*) required for connecting to the current instance.

<uri>.params.*

Enterprise Edition

TLS traffic encryption is supported by the Enterprise Edition only.

URI parameters that can be used in the iproto.listen.<uri>.params and iproto.advertise.<peer_or_sharding>.params options.

Примечание

Note that <uri>.params.* options don’t have corresponding environment variables for URIs specified in iproto.listen.

<uri>.params.transport

Allows you to enable traffic encryption for client-server communications over binary connections. In a Tarantool cluster, one instance might act as the server that accepts connections from other instances and the client that connects to other instances.

<uri>.params.transport accepts one of the following values:

  • plain (default): turn off traffic encryption.
  • ssl: encrypt traffic by using the TLS 1.2 protocol (Enterprise Edition only).

Example

The example below demonstrates how to enable traffic encryption by using a self-signed server certificate. The following parameters are specified for each instance:

  • ssl_cert_file: a path to an SSL certificate file.
  • ssl_key_file: a path to a private SSL key file.
replicaset001:
  replication:
    failover: manual
  leader: instance001
  iproto:
    advertise:
      peer:
        login: replicator
  instances:
    instance001:
      iproto:
        listen:
        - uri: '127.0.0.1:3301'
          params:
            transport: 'ssl'
            ssl_cert_file: 'certs/server.crt'
            ssl_key_file: 'certs/server.key'
    instance002:
      iproto:
        listen:
        - uri: '127.0.0.1:3302'
          params:
            transport: 'ssl'
            ssl_cert_file: 'certs/server.crt'
            ssl_key_file: 'certs/server.key'
    instance003:
      iproto:
        listen:
        - uri: '127.0.0.1:3303'
          params:
            transport: 'ssl'
            ssl_cert_file: 'certs/server.crt'
            ssl_key_file: 'certs/server.key'

Example on Github: ssl_without_ca


Type: string
Default: „plain“
Environment variable: TT_IPROTO_ADVERTISE_PEER_PARAMS_TRANSPORT, TT_IPROTO_ADVERTISE_SHARDING_PARAMS_TRANSPORT
<uri>.params.ssl_ca_file

(Optional) A path to a trusted certificate authorities (CA) file. If not set, the peer won’t be checked for authenticity.

Both a server and a client can use the ssl_ca_file parameter:

  • If it’s on the server side, the server verifies the client.
  • If it’s on the client side, the client verifies the server.
  • If both sides have the CA files, the server and the client verify each other.

See also: <uri>.params.transport


Type: string
Default: nil
Environment variable: TT_IPROTO_ADVERTISE_PEER_PARAMS_SSL_CA_FILE, TT_IPROTO_ADVERTISE_SHARDING_PARAMS_SSL_CA_FILE
<uri>.params.ssl_cert_file

A path to an SSL certificate file:

  • For a server, it’s mandatory.
  • For a client, it’s mandatory if the ssl_ca_file parameter is set for a server; otherwise, optional.

See also: <uri>.params.transport


Type: string
Default: nil
Environment variable: TT_IPROTO_ADVERTISE_PEER_PARAMS_SSL_CERT_FILE, TT_IPROTO_ADVERTISE_SHARDING_PARAMS_SSL_CERT_FILE
<uri>.params.ssl_ciphers

(Optional) A colon-separated (:) list of SSL cipher suites the connection can use. Note that the list is not validated: if a cipher suite is unknown, Tarantool ignores it, doesn’t establish the connection, and writes to the log that no shared cipher was found.

The supported cipher suites are:

  • ECDHE-ECDSA-AES256-GCM-SHA384
  • ECDHE-RSA-AES256-GCM-SHA384
  • DHE-RSA-AES256-GCM-SHA384
  • ECDHE-ECDSA-CHACHA20-POLY1305
  • ECDHE-RSA-CHACHA20-POLY1305
  • DHE-RSA-CHACHA20-POLY1305
  • ECDHE-ECDSA-AES128-GCM-SHA256
  • ECDHE-RSA-AES128-GCM-SHA256
  • DHE-RSA-AES128-GCM-SHA256
  • ECDHE-ECDSA-AES256-SHA384
  • ECDHE-RSA-AES256-SHA384
  • DHE-RSA-AES256-SHA256
  • ECDHE-ECDSA-AES128-SHA256
  • ECDHE-RSA-AES128-SHA256
  • DHE-RSA-AES128-SHA256
  • ECDHE-ECDSA-AES256-SHA
  • ECDHE-RSA-AES256-SHA
  • DHE-RSA-AES256-SHA
  • ECDHE-ECDSA-AES128-SHA
  • ECDHE-RSA-AES128-SHA
  • DHE-RSA-AES128-SHA
  • AES256-GCM-SHA384
  • AES128-GCM-SHA256
  • AES256-SHA256
  • AES128-SHA256
  • AES256-SHA
  • AES128-SHA
  • GOST2012-GOST8912-GOST8912
  • GOST2001-GOST89-GOST89

For detailed information on SSL ciphers and their syntax, refer to OpenSSL documentation.

See also: <uri>.params.transport


Type: string
Default: nil
Environment variable: TT_IPROTO_ADVERTISE_PEER_PARAMS_SSL_CIPHERS, TT_IPROTO_ADVERTISE_SHARDING_PARAMS_SSL_CIPHERS
<uri>.params.ssl_key_file

A path to a private SSL key file:

  • For a server, it’s mandatory.
  • For a client, it’s mandatory if the ssl_ca_file parameter is set for a server; otherwise, optional.

If the private key is encrypted, provide a password for it in the ssl_password or ssl_password_file parameter.

See also: <uri>.params.transport


Type: string
Default: nil
Environment variable: TT_IPROTO_ADVERTISE_PEER_PARAMS_SSL_KEY_FILE, TT_IPROTO_ADVERTISE_SHARDING_PARAMS_SSL_KEY_FILE
<uri>.params.ssl_password

(Optional) A password for an encrypted private SSL key provided using ssl_key_file. Alternatively, the password can be provided in ssl_password_file.

Tarantool applies the ssl_password and ssl_password_file parameters in the following order:

  1. If ssl_password is provided, Tarantool tries to decrypt the private key with it.
  2. If ssl_password is incorrect or isn’t provided, Tarantool tries all passwords from ssl_password_file one by one in the order they are written.
  3. If ssl_password and all passwords from ssl_password_file are incorrect, or none of them is provided, Tarantool treats the private key as unencrypted.

See also: <uri>.params.transport


Type: string
Default: nil
Environment variable: TT_IPROTO_ADVERTISE_PEER_PARAMS_SSL_PASSWORD, TT_IPROTO_ADVERTISE_SHARDING_PARAMS_SSL_PASSWORD
<uri>.params.ssl_password_file

(Optional) A text file with one or more passwords for encrypted private SSL keys provided using ssl_key_file (each on a separate line). Alternatively, the password can be provided in ssl_password.

See also: <uri>.params.transport


Type: string
Default: nil
Environment variable: TT_IPROTO_ADVERTISE_PEER_PARAMS_SSL_PASSWORD_FILE, TT_IPROTO_ADVERTISE_SHARDING_PARAMS_SSL_PASSWORD_FILE

groups

The groups section provides the ability to define the full topology of a Tarantool cluster.

Примечание

groups can be defined in the global scope only.

groups.<group_name>

A group name.

The following rules are applied to group names:

  • The maximum number of symbols is 63.
  • Should start with a letter.
  • Can contain lowercase letters (a-z).
  • Can contain digits (0-9).
  • Can contain the following characters: -, _.
groups.<group_name>.replicasets

Replica sets that belong to this group. See replicasets.

groups.<group_name>.<config_parameter>

Any configuration parameter that can be defined in the group scope. For example, iproto and database configuration parameters defined at the group level are applied to all instances in this group.

replicasets

Примечание

replicasets can be defined in the group scope only.

replicasets.<replicaset_name>

A replica set name.

Note that the rules applied to a replica set name are the same as for groups. Learn more in groups.<group_name>.

replicasets.<replicaset_name>.leader

A replica set leader. This option can be used to set a replica set leader when manual replication.failover is used.

To perform controlled failover, <replicaset_name>.leader can be temporarily removed or set to null.

Example

replication:
  failover: manual

groups:
  group001:
    replicasets:
      replicaset001:
        leader: instance001
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
          instance002:
            iproto:
              listen:
              - uri: '127.0.0.1:3302'
          instance003:
            iproto:
              listen:
              - uri: '127.0.0.1:3303'
replicasets.<replicaset_name>.bootstrap_leader

A bootstrap leader for a replica set. To specify a bootstrap leader manually, you need to set replication.bootstrap_strategy to config.

Example

groups:
  group001:
    replicasets:
      replicaset001:
        replication:
          bootstrap_strategy: config
        bootstrap_leader: instance001
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
          instance002:
            iproto:
              listen:
              - uri: '127.0.0.1:3302'
          instance003:
            iproto:
              listen:
              - uri: '127.0.0.1:3303'
replicasets.<replicaset_name>.instances

Instances that belong to this replica set. See instances.

replicasets.<replicaset_name>.<config_parameter>

Any configuration parameter that can be defined in the replica set scope. For example, iproto and database configuration parameters defined at the replica set level are applied to all instances in this replica set.

instances

Примечание

instances can be defined in the replica set scope only.

instances.<instance_name>

An instance name.

Note that the rules applied to an instance name are the same as for groups. Learn more in groups.<group_name>.

instances.<instance_name>.<config_parameter>

Any configuration parameter that can be defined in the instance scope. For example, iproto and database configuration parameters defined at the instance level are applied to this instance only.

labels

The labels section allows adding custom attributes to the configuration. Attributes must be key: value pairs with string keys and values.

Примечание

labels can be defined in any scope.

labels.<label_name>

A value of the label with the specified name.

Example

The example below shows how to define labels on the replica set and instance levels:

groups:
  group001:
    replicasets:
      replicaset001:
        labels:
          dc: 'east'
          production: 'false'
        instances:
          instance001:
            labels:
              rack: '10'
              production: 'true'

See also: Adding labels

log

The log section defines configuration parameters related to logging. To handle logging in your application, use the log module.

Примечание

log can be defined in any scope.

log.to

Define a location Tarantool sends logs to. This option accepts the following values:

  • stderr: write logs to the standard error stream.
  • file: write logs to a file (see log.file).
  • pipe: start a program and write logs to its standard input (see log.pipe).
  • syslog: write logs to a system logger (see log.syslog.*).

Type: string
Default: „stderr“
Environment variable: TT_LOG_TO
log.file

Specify a file for logs destination. To write logs to a file, you need to set log.to to file. Otherwise, log.file is ignored.

Example

The example below shows how to write logs to a file placed in the specified directory:

log:
  to: file
  file: var/log/{{ instance_name }}/instance.log

Example on GitHub: log_file


Type: string
Default: „var/log/{{ instance_name }}/tarantool.log“
Environment variable: TT_LOG_FILE
log.format

Specify a format that is used for a log entry. The following formats are supported:

  • plain: a log entry is formatted as plain text. Example:

    2024-04-09 11:00:10.369 [12089] main/104/interactive I> log level 5 (INFO)

  • json: a log entry is formatted as JSON and includes additional fields. Example:

    {
  "time": "2024-04-09T11:00:57.174+0300",
  "level": "INFO",
  "message": "log level 5 (INFO)",
  "pid": 12160,
  "cord_name": "main",
  "fiber_id": 104,
  "fiber_name": "interactive",
  "file": "src/main.cc",
  "line": 498
}

Type: string
Default: „plain“
Environment variable: TT_LOG_FORMAT
log.level

Specify the level of detail logs have. There are the following levels:

  • 0 – fatal
  • 1 – syserror
  • 2 – error
  • 3 – crit
  • 4 – warn
  • 5 – info
  • 6 – verbose
  • 7 – debug

By setting log.level, you can enable logging of all events with severities above or equal to the given level.

Example

The example below shows how to log all events with severities above or equal to the VERBOSE level.

log:
  level: 'verbose'

Example on GitHub: log_level


Type: number, string
Default: 5
Environment variable: TT_LOG_LEVEL
log.modules

Configure the specified log levels (log.level) for different modules.

You can specify a logging level for the following module types:

Example 1: Set log levels for files that use the default logger

Suppose you have two identical modules placed by the following paths: test/module1.lua and test/module2.lua. These modules use the default logger and look as follows:

return {
    say_hello = function()
        local log = require('log')
        log.info('Info message from module1')
    end
}

To configure logging levels, you need to provide module names corresponding to paths to these modules:

log:
  modules:
    test.module1: 'verbose'
    test.module2: 'error'
app:
  file: 'app.lua'

To load these modules in your application (app.lua), you need to add the corresponding require directives:

module1 = require('test.module1')
module2 = require('test.module2')

Given that module1 has the verbose logging level and module2 has the error level, calling module1.say_hello() shows a message but module2.say_hello() is swallowed:

-- Prints 'info' messages --
module1.say_hello()
--[[
[92617] main/103/interactive/test.logging.module1 I> Info message from module1
---
...
--]]

-- Swallows 'info' messages --
module2.say_hello()
--[[
---
...
--]]

Example on GitHub: log_existing_modules

Example 2: Set log levels for modules that use custom loggers

This example shows how to set the verbose level for module1 and the error level for module2:

log:
  modules:
    module1: 'verbose'
    module2: 'error'
app:
  file: 'app.lua'

To create custom loggers in your application (app.lua), call the log.new() function:

-- Creates new loggers --
module1_log = require('log').new('module1')
module2_log = require('log').new('module2')

Given that module1 has the verbose logging level and module2 has the error level, calling module1_log.info() shows a message but module2_log.info() is swallowed:

-- Prints 'info' messages --
module1_log.info('Info message from module1')
--[[
[16300] main/103/interactive/module1 I> Info message from module1
---
...
--]]

-- Swallows 'debug' messages --
module1_log.debug('Debug message from module1')
--[[
---
...
--]]

-- Swallows 'info' messages --
module2_log.info('Info message from module2')
--[[
---
...
--]]

Example on GitHub: log_new_modules

Example 3: Set a log level for C modules

This example shows how to set the info level for the tarantool module:

log:
  modules:
    tarantool: 'info'
app:
  file: 'app.lua'

The specified level affects messages logged from C modules:

ffi = require('ffi')

-- Prints 'info' messages --
ffi.C._say(ffi.C.S_INFO, nil, 0, nil, 'Info message from C module')
--[[
[6024] main/103/interactive I> Info message from C module
---
...
--]]

-- Swallows 'debug' messages --
ffi.C._say(ffi.C.S_DEBUG, nil, 0, nil, 'Debug message from C module')
--[[
---
...
--]]

The example above uses the LuaJIT ffi library to call C functions provided by the say module.

Example on GitHub: log_existing_c_modules


Type: map
Default: box.NULL
Environment variable: TT_LOG_MODULES
log.nonblock

Specify the logging behavior if the system is not ready to write. If set to true, Tarantool does not block during logging if the system is non-writable and writes a message instead. Using this value may improve logging performance at the cost of losing some log messages.

Примечание

The option only has an effect if the log.to is set to syslog or pipe.


Type: boolean
Default: false
Environment variable: TT_LOG_NONBLOCK
log.pipe

Start a program and write logs to its standard input (stdin). To send logs to a program’s standard input, you need to set log.to to pipe.

Example

In the example below, Tarantool writes logs to the standard input of cronolog:

log:
  to: pipe
  pipe: 'cronolog tarantool.log'

Example on GitHub: log_pipe


Type: string
Default: box.NULL
Environment variable: TT_LOG_PIPE

log.syslog.*

log.syslog.facility

Specify the syslog facility to be used when syslog is enabled. To write logs to syslog, you need to set log.to to syslog.


Type: string
Possible values: „auth“, „authpriv“, „cron“, „daemon“, „ftp“, „kern“, „lpr“, „mail“, „news“, „security“, „syslog“, „user“, „uucp“, „local0“, „local1“, „local2“, „local3“, „local4“, „local5“, „local6“, „local7“
Default: „local7“
Environment variable: TT_LOG_SYSLOG_FACILITY
log.syslog.identity

Specify an application name used to identify Tarantool messages in syslog logs. To write logs to syslog, you need to set log.to to syslog.


Type: string
Default: „tarantool“
Environment variable: TT_LOG_SYSLOG_IDENTITY
log.syslog.server

Set a location of a syslog server. This option accepts one of the following values:

  • An IPv4 address. Example: 127.0.0.1:514.
  • A Unix socket path starting with unix:. Examples: unix:/dev/log on Linux or unix:/var/run/syslog on macOS.

To write logs to syslog, you need to set log.to to syslog.

Example

In the example below, Tarantool writes logs to a syslog server that listens for logging messages on the 127.0.0.1:514 address:

log:
  to: syslog
  syslog:
    server: '127.0.0.1:514'

Example on GitHub: log_syslog


Type: string
Default: box.NULL
Environment variable: TT_LOG_SYSLOG_SERVER

memtx

The memtx section is used to configure parameters related to the memtx engine.

Примечание

memtx can be defined in any scope.

memtx.allocator

Specify the allocator that manages memory for memtx tuples. Possible values:

  • system – the memory is allocated as needed, checking that the quota is not exceeded. THe allocator is based on the malloc function.
  • small – a slab allocator. The allocator repeatedly uses a memory block to allocate objects of the same type. Note that this allocator is prone to unresolvable fragmentation on specific workloads, so you can switch to system in such cases.

Type: string
Default: „small“
Environment variable: TT_MEMTX_ALLOCATOR
memtx.max_tuple_size

Size of the largest allocation unit for the memtx storage engine in bytes. It can be increased if it is necessary to store large tuples.


Type: integer
Default: 1048576
Environment variable: TT_MEMTX_MAX_TUPLE_SIZE
memtx.memory

The amount of memory in bytes that Tarantool allocates to store tuples. When the limit is reached, INSERT and UPDATE requests fail with the ER_MEMORY_ISSUE error. The server does not go beyond the memtx.memory limit to allocate tuples, but there is additional memory used to store indexes and connection information.

Example

In the example below, the memory size is set to 1 GB (1073741824 bytes).

memtx:
  memory: 1073741824

Type: integer
Default: 268435456
Environment variable: TT_MEMTX_MEMORY
memtx.min_tuple_size

Size of the smallest allocation unit in bytes. It can be decreased if most of the tuples are very small.


Type: integer
Default: 16
Possible values: between 8 and 1048280 inclusive
Environment variable: TT_MEMTX_MIN_TUPLE_SIZE
memtx.slab_alloc_factor

The multiplier for computing the sizes of memory chunks that tuples are stored in. A lower value may result in less wasted memory depending on the total amount of memory available and the distribution of item sizes.

See also: memtx.slab_alloc_granularity


Type: number
Default: 1.05
Possible values: between 1 and 2 inclusive
Environment variable: TT_MEMTX_SLAB_ALLOC_FACTOR
memtx.slab_alloc_granularity

Specify the granularity in bytes of memory allocation in the small allocator. The memtx.slab_alloc_granularity value should meet the following conditions:

  • The value is a power of two.
  • The value is greater than or equal to 4.

Below are few recommendations on how to adjust the memtx.slab_alloc_granularity option:

  • If the tuples in space are small and have about the same size, set the option to 4 bytes to save memory.
  • If the tuples are different-sized, increase the option value to allocate tuples from the same mempool (memory pool).

See also: memtx.slab_alloc_factor


Type: integer
Default: 8
Environment variable: TT_MEMTX_SLAB_ALLOC_GRANULARITY
memtx.sort_threads

The number of threads from the thread pool used to sort keys of secondary indexes on loading a memtx database. The minimum value is 1, the maximum value is 256. The default is to use all available cores.

Примечание

Since 3.0.0, this option replaces the approach when OpenMP threads are used to parallelize sorting. For backward compatibility, the OMP_NUM_THREADS environment variable is taken into account to set the number of sorting threads.


Type: integer
Default: box.NULL
Environment variable: TT_MEMTX_SORT_THREADS

metrics

The metrics section defines configuration parameters for metrics.

Примечание

metrics can be defined in any scope.

metrics.exclude

An array containing the metrics to turn off. The array can contain the same values as the exclude configuration parameter passed to metrics.cfg().

Example

metrics:
  include: [ all ]
  exclude: [ vinyl ]
  labels:
    alias: '{{ instance_name }}'

Type: array
Default: []
Environment variable: TT_METRICS_EXCLUDE
metrics.include

An array containing the metrics to turn on. The array can contain the same values as the include configuration parameter passed to metrics.cfg().


Type: array
Default: [ all ]
Environment variable: TT_METRICS_INCLUDE
metrics.labels

Global labels to be added to every observation.


Type: map
Default: { alias = names.instance_name }
Environment variable: TT_METRICS_LABELS

process

The process section defines configuration parameters of the Tarantool process in the system.

Примечание

process can be defined in any scope.

process.background

Run the server as a daemon process.

If this option is set to true, Tarantool log location defined by the log.to option should be set to file, pipe, or syslog – anything other than stderr, the default, because a daemon process is detached from a terminal and it can’t write to the terminal’s stderr.

Важно

Do not enable the background mode for applications intended to run by the tt utility. For more information, see the tt start reference.


Type: boolean
Default: false
Environment variable: TT_PROCESS_BACKGROUND
process.coredump

Create coredump files.

Usually, an administrator needs to call ulimit -c unlimited (or set corresponding options in systemd’s unit file) before running a Tarantool process to get core dumps. If process.coredump is enabled, Tarantool sets the corresponding resource limit by itself and the administrator doesn’t need to call ulimit -c unlimited (see man 3 setrlimit).

This option also sets the state of the dumpable attribute, which is enabled by default, but may be dropped in some circumstances (according to man 2 prctl, see PR_SET_DUMPABLE).


Type: boolean
Default: false
Environment variable: TT_PROCESS_COREDUMP
process.title

Add the given string to the server’s process title (it is shown in the COMMAND column for the Linux commands ps -ef and top -c).

For example, if you set the option to myservice - {{ instance_name }}:

process:
  title: myservice - {{ instance_name }}

ps -ef might show the Tarantool server process like this:

$ ps -ef | grep tarantool
503      68100 68098  0 10:33 pts/2    00:00.10 tarantool <running>: myservice instance1

Type: string
Default: „tarantool - {{ instance_name }}“
Environment variable: TT_PROCESS_TITLE
process.pid_file

Store the process id in this file.

This option may contain a relative file path. In this case, it is interpreted as relative to process.work_dir.


Type: string
Default: „var/run/{{ instance_name }}/tarantool.pid“
Environment variable: TT_PROCESS_PID_FILE
process.strip_core

Whether coredump files should not include memory allocated for tuples – this memory can be large if Tarantool runs under heavy load. Setting to true means «do not include».


Type: boolean
Default: true
Environment variable: TT_PROCESS_STRIP_CORE
process.username

The name of the system user to switch to after start.


Type: string
Default: box.NULL
Environment variable: TT_PROCESS_USERNAME
process.work_dir

A directory where Tarantool working files will be stored (database files, logs, a PID file, a console Unix socket, and other files if an application generates them in the current directory). The server instance switches to process.work_dir with chdir(2) after start.

If set as a relative file path, it is relative to the current working directory, from where Tarantool is started. If not specified, defaults to the current working directory.

Other directory and file parameters, if set as relative paths, are interpreted as relative to process.work_dir, for example, directories for storing snapshots and write-ahead logs.


Type: string
Default: box.NULL
Environment variable: TT_PROCESS_WORK_DIR

replication

The replication section defines configuration parameters related to replication.

replication.anon

Whether to make the current instance act as an anonymous replica. Anonymous replicas are read-only and can be used, for example, for backups.

To make the specified instance act as an anonymous replica, set replication.anon to true:

instance003:
  replication:
    anon: true

You can find the full example on GitHub: anonymous_replica.

Anonymous replicas are not displayed in the box.info.replication section. You can check their status using box.info.replication_anon().

While anonymous replicas are read-only, you can write data to replication-local and temporary spaces (created with is_local = true and temporary = true, respectively). Given that changes to replication-local spaces are allowed, an anonymous replica might increase the 0 component of the vclock value.

Here are the limitations of having anonymous replicas in a replica set:

Примечание

Anonymous replicas are not registered in the _cluster space. This means that there is no limitation on the number of anonymous replicas in a replica set.


Type: boolean
Default: false
Environment variable: TT_REPLICATION_ANON
replication.bootstrap_strategy

Specifies a strategy used to bootstrap a replica set. The following strategies are available:

  • auto: a node doesn’t boot if half or more of the other nodes in a replica set are not connected. For example, if a replica set contains 2 or 3 nodes, a node requires 2 connected instances. In the case of 4 or 5 nodes, at least 3 connected instances are required. Moreover, a bootstrap leader fails to boot unless every connected node has chosen it as a bootstrap leader.
  • config: use the specified node to bootstrap a replica set. To specify the bootstrap leader, use the <replicaset_name>.bootstrap_leader option.
  • supervised: a bootstrap leader isn’t chosen automatically but should be appointed using box.ctl.make_bootstrap_leader() on the desired node.
  • legacy (deprecated since 2.11.0): a node requires the replication_connect_quorum number of other nodes to be connected. This option is added to keep the compatibility with the current versions of Cartridge and might be removed in the future.

Type: string
Default: auto
Environment variable: TT_REPLICATION_BOOTSTRAP_STRATEGY
replication.connect_timeout

A timeout (in seconds) a replica waits when trying to connect to a master in a cluster. See orphan status for details.

This parameter is different from replication.timeout, which a master uses to disconnect a replica when the master receives no acknowledgments of heartbeat messages.


Type: number
Default: 30
Environment variable: TT_REPLICATION_CONNECT_TIMEOUT
replication.election_mode

A role of a replica set node in the leader election process.

The possible values are:

  • off: a node doesn’t participate in the election activities.
  • voter: a node can participate in the election process but can’t be a leader.
  • candidate: a node should be able to become a leader.
  • manual: allow to control which instance is the leader explicitly instead of relying on automated leader election. By default, the instance acts like a voter – it is read-only and may vote for other candidate instances. Once box.ctl.promote() is called, the instance becomes a candidate and starts a new election round. If the instance wins the elections, it becomes a leader but won’t participate in any new elections.

Примечание

You can set replication.election_mode to a value other than off if the replication.failover mode is election.


Type: string
Default: box.NULL (the actual default value depends on replication.failover)
Environment variable: TT_REPLICATION_ELECTION_MODE
replication.election_timeout

Specifies the timeout (in seconds) between election rounds in the leader election process if the previous round ended up with a split vote.

It is quite big, and for most of the cases, it can be lowered to 300-400 ms.

To avoid the split vote repeat, the timeout is randomized on each node during every new election, from 100% to 110% of the original timeout value. For example, if the timeout is 300 ms and there are 3 nodes started the election simultaneously in the same term, they can set their election timeouts to 300, 310, and 320 respectively, or to 305, 302, and 324, and so on. In that way, the votes will never be split because the election on different nodes won’t be restarted simultaneously.


Type: number
Default: 5
Environment variable: TT_REPLICATION_ELECTION_TIMEOUT
replication.election_fencing_mode

Specifies the leader fencing mode that affects the leader election process. When the parameter is set to soft or strict, the leader resigns its leadership if it has less than replication.synchro_quorum of alive connections to the cluster nodes. The resigning leader receives the status of a follower in the current election term and becomes read-only.

  • In soft mode, a connection is considered dead if there are no responses for 4 * replication.timeout seconds both on the current leader and the followers.
  • In strict mode, a connection is considered dead if there are no responses for 2 * replication.timeout seconds on the current leader and 4 * replication.timeout seconds on the followers. This improves the chances that there is only one leader at any time.

Fencing applies to the instances that have the replication.election_mode set to candidate or manual. To turn off leader fencing, set election_fencing_mode to off.


Type: string
Default: soft
Possible values: off, soft, strict
Environment variable: TT_REPLICATION_ELECTION_FENCING_MODE
replication.failover

A failover mode used to take over a master role when the current master instance fails. The following modes are available:

See also: Replication tutorials

Примечание

replication.failover can be defined in the global, group, and replica set scope.

Example

In the example below, the following configuration options are specified:

  • In the credentials section, the replicator user with the replication role is created.
  • iproto.advertise.peer specifies that other instances should connect to an address defined in iproto.listen using the replicator user.
  • replication.failover specifies that a master instance should be set manually.
  • <replicaset_name>.leader sets instance001 as a replica set leader.
credentials:
  users:
    replicator:
      password: 'topsecret'
      roles: [replication]

iproto:
  advertise:
    peer:
      login: replicator

replication:
  failover: manual

groups:
  group001:
    replicasets:
      replicaset001:
        leader: instance001
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
          instance002:
            iproto:
              listen:
              - uri: '127.0.0.1:3302'
          instance003:
            iproto:
              listen:
              - uri: '127.0.0.1:3303'

Type: string
Default: off
Environment variable: TT_REPLICATION_FAILOVER
replication.peers

URIs of instances that constitute a replica set. These URIs are used by an instance to connect to another instance as a replica.

Alternatively, you can use iproto.advertise.peer to specify a URI used to advertise the current instance to other cluster members.

Example

In the example below, the following configuration options are specified:

  • In the credentials section, the replicator user with the replication role is created.
  • replication.peers specifies URIs of replica set instances.
credentials:
  users:
    replicator:
      password: 'topsecret'
      roles: [replication]

replication:
  peers:
  - replicator:topsecret@127.0.0.1:3301
  - replicator:topsecret@127.0.0.1:3302
  - replicator:topsecret@127.0.0.1:3303

Type: array
Default: box.NULL
Environment variable: TT_REPLICATION_PEERS
replication.skip_conflict

By default, if a replica adds a unique key that another replica has added, replication stops with the ER_TUPLE_FOUND error. If replication.skip_conflict is set to true, such errors are ignored.

Примечание

Instead of saving the broken transaction to the write-ahead log, it is written as NOP (No operation).


Type: boolean
Default: false
Environment variable: TT_REPLICATION_SKIP_CONFLICT
replication.sync_lag

The maximum delay (in seconds) between the time when data is written to the master and the time when it is written to a replica. If replication.sync_lag is set to nil or 365 * 100 * 86400 (TIMEOUT_INFINITY), a replica is always considered to be «synced».

Примечание

This parameter is ignored during bootstrap. See orphan status for details.


Type: number
Default: 10
Environment variable: TT_REPLICATION_SYNC_LAG
replication.sync_timeout

The timeout (in seconds) that a node waits when trying to sync with other nodes in a replica set after connecting or during a configuration update. This could fail indefinitely if replication.sync_lag is smaller than network latency, or if the replica cannot keep pace with master updates. If replication.sync_timeout expires, the replica enters orphan status.


Type: number
Default: 0
Environment variable: TT_REPLICATION_SYNC_TIMEOUT
replication.synchro_quorum

A number of replicas that should confirm the receipt of a synchronous transaction before it can finish its commit.

This option supports dynamic evaluation of the quorum number. For example, the default value is N / 2 + 1 where N is the current number of replicas registered in a cluster. Once any replicas are added or removed, the expression is re-evaluated automatically.

Note that the default value (at least 50% of the cluster size + 1) guarantees data reliability. Using a value less than the canonical one might lead to unexpected results, including a split-brain.

replication.synchro_quorum is not used on replicas. If the master fails, the pending synchronous transactions will be kept waiting on the replicas until a new master is elected.

Примечание

replication.synchro_quorum does not account for anonymous replicas.


Type: string, number
Default: N / 2 + 1
Environment variable: TT_REPLICATION_SYNCHRO_QUORUM
replication.synchro_timeout

For synchronous replication only. Specify how many seconds to wait for a synchronous transaction quorum replication until it is declared failed and is rolled back.

It is not used on replicas, so if the master fails, the pending synchronous transactions will be kept waiting on the replicas until a new master is elected.


Type: number
Default: 5
Environment variable: TT_REPLICATION_SYNCHRO_TIMEOUT
replication.threads

The number of threads spawned to decode the incoming replication data.

In most cases, one thread is enough for all incoming data. Possible values range from 1 to 1000. If there are multiple replication threads, connections to serve are distributed evenly between the threads.


Type: integer
Default: 1
Environment variable: TT_REPLICATION_THREADS
replication.timeout

A time interval (in seconds) used by a master to send heartbeat requests to a replica when there are no updates to send to this replica. For each request, a replica should return a heartbeat acknowledgment.

If a master or replica gets no heartbeat message for 4 * replication.timeout seconds, a connection is dropped and a replica tries to reconnect to the master.

See also: Monitoring a replica set


Type: number
Default: 1
Environment variable: TT_REPLICATION_TIMEOUT

roles

This section describes configuration parameters related to application roles.

Примечание

Configuration parameters related to roles can be defined in any scope.

roles

Specify the roles of an instance. To specify a role’s configuration, use the roles_cfg option.

See also: Enabling and configuring roles


Type: array
Default: nil
Environment variable: TT_ROLES
roles_cfg

Specify a role’s configuration. This option accepts a role name as the key and a role’s configuration as the value. To specify the roles of an instance, use the roles option.

See also: Enabling and configuring roles

Совет

The experimental.config.utils.schema built-in module provides an API for managing user-defined configurations of applications (app.cfg) and roles (roles_cfg).


Type: map
Default: nil
Environment variable: TT_ROLES_CFG

security

Enterprise Edition

Configuring security parameters is available in the Enterprise Edition only.

The security section defines configuration parameters related to various security settings.

Примечание

security can be defined in any scope.

security.auth_delay

Specify a period of time (in seconds) that a specific user should wait for the next attempt after failed authentication.

The security.auth_retries option lets a client try to authenticate the specified number of times before security.auth_delay is enforced.

In the configuration below, Tarantool lets a client try to authenticate with the same username three times. At the fourth attempt, the authentication delay configured with security.auth_delay is enforced. This means that a client should wait 10 seconds after the first failed attempt.

security:
  auth_delay: 10
  auth_retries: 2

Type: number
Default: 0
Environment variable: TT_SECURITY_AUTH_DELAY
security.auth_retries

Specify the maximum number of authentication retries allowed before security.auth_delay is enforced. The default value is 0, which means security.auth_delay is enforced after the first failed authentication attempt.

The retry counter is reset after security.auth_delay seconds since the first failed attempt. For example, if a client tries to authenticate fewer than security.auth_retries times within security.auth_delay seconds, no authentication delay is enforced. The retry counter is also reset after any successful authentication attempt.


Type: integer
Default: 0
Environment variable: TT_SECURITY_AUTH_RETRIES
security.auth_type

Specify a protocol used to authenticate users. The possible values are:

  • chap-sha1: use the CHAP protocol with SHA-1 hashing applied to passwords.
  • pap-sha256: use PAP authentication with the SHA256 hashing algorithm.

Note that CHAP stores password hashes in the _user space unsalted. If an attacker gains access to the database, they may crack a password, for example, using a rainbow table. For PAP, a password is salted with a user-unique salt before saving it in the database, which keeps the database protected from cracking using a rainbow table.

To enable PAP, specify the security.auth_type option as follows:

security:
  auth_type: 'pap-sha256'

Type: string
Default: „chap-sha1“
Environment variable: TT_SECURITY_AUTH_TYPE
security.disable_guest

If true, turn off access over remote connections from unauthenticated or guest users. This option affects connections between cluster members and net.box connections.


Type: boolean
Default: false
Environment variable: TT_SECURITY_DISABLE_GUEST
security.password_enforce_digits

If true, a password should contain digits (0-9).


Type: boolean
Default: false
Environment variable: TT_SECURITY_PASSWORD_ENFORCE_DIGITS
security.password_enforce_lowercase

If true, a password should contain lowercase letters (a-z).


Type: boolean
Default: false
Environment variable: TT_SECURITY_PASSWORD_ENFORCE_LOWERCASE
security.password_enforce_specialchars

If true, a password should contain at least one special character (such as &|?!@$).


Type: boolean
Default: false
Environment variable: TT_SECURITY_PASSWORD_ENFORCE_SPECIALCHARS
security.password_enforce_uppercase

If true, a password should contain uppercase letters (A-Z).


Type: boolean
Default: false
Environment variable: TT_SECURITY_PASSWORD_ENFORCE_UPPERCASE
security.password_history_length

Specify the number of unique new user passwords before an old password can be reused.

Примечание

Tarantool uses the auth_history field in the box.space._user system space to store user passwords.


Type: integer
Default: 0
Environment variable: TT_SECURITY_PASSWORD_HISTORY_LENGTH
security.password_lifetime_days

Specify the maximum period of time (in days) a user can use the same password. When this period ends, a user gets the «Password expired» error on a login attempt. To restore access for such users, use box.schema.user.passwd.

Примечание

The default 0 value means that a password never expires.


Type: integer
Default: 0
Environment variable: TT_SECURITY_PASSWORD_LIFETIME_DAYS
security.password_min_length

Specify the minimum number of characters for a password.


Type: integer
Default: 0
Environment variable: TT_SECURITY_PASSWORD_MIN_LENGTH
security.secure_erasing

If true, forces Tarantool to overwrite a data file a few times before deletion to render recovery of a deleted file impossible. The option applies to both .xlog and .snap files as well as Vinyl data files.


Type: boolean
Default: false
Environment variable: TT_SECURITY_SECURE_ERASING

sharding

The sharding section defines configuration parameters related to sharding.

Примечание

Sharding support requires installing the vshard module. The minimum required version of vshard is 0.1.25.

sharding.bucket_count

The total number of buckets in a cluster. Learn more in Bucket count.

Примечание

This option should be defined at the global level.

Example

sharding:
  bucket_count: 1000

Type: integer
Default: 3000
Environment variable: TT_SHARDING_BUCKET_COUNT
sharding.discovery_mode

A mode of the background discovery fiber used by the router to find buckets. Learn more in vshard.router.discovery_set().

Примечание

This option should be defined at the global level.


Type: string
Default: „on“
Possible values: „on“, „off“, „once“
Environment variable: TT_SHARDING_DISCOVERY_MODE
sharding.failover_ping_timeout

The timeout (in seconds) after which a node is considered unavailable if there are no responses during this period. The failover fiber is used to detect if a node is down.

Примечание

This option should be defined at the global level.


Type: number
Default: 5
Environment variable: TT_SHARDING_FAILOVER_PING_TIMEOUT
sharding.lock

Whether a replica set is locked. A locked replica set cannot receive new buckets nor migrate its own buckets.

Примечание

sharding.lock can be specified at the replica set level or higher.


Type: boolean
Default: nil
Environment variable: TT_SHARDING_LOCK
sharding.rebalancer_disbalance_threshold

The maximum bucket disbalance threshold (in percent). The disbalance is calculated for each replica set using the following formula:

|etalon_bucket_count - real_bucket_count| / etalon_bucket_count * 100

Примечание

This option should be defined at the global level.


Type: number
Default: 1
Environment variable: TT_SHARDING_REBALANCER_DISBALANCE_THRESHOLD
sharding.rebalancer_max_receiving

The maximum number of buckets that can be received in parallel by a single replica set. This number must be limited because the rebalancer sends a large number of buckets from the existing replica sets to the newly added one. This produces a heavy load on the new replica set.

Примечание

This option should be defined at the global level.

Example

Suppose, rebalancer_max_receiving is equal to 100 and bucket_count is equal to 1000. There are 3 replica sets with 333, 333, and 334 buckets on each respectively. When a new replica set is added, each replica set’s etalon_bucket_count becomes equal to 250. Rather than receiving all 250 buckets at once, the new replica set receives 100, 100, and 50 buckets sequentially.


Type: integer
Default: 100
Environment variable: TT_SHARDING_REBALANCER_MAX_RECEIVING
sharding.rebalancer_max_sending

The degree of parallelism for parallel rebalancing.

Примечание

This option should be defined at the global level.


Type: integer
Default: 1
Maximum: 15
Environment variable: TT_SHARDING_REBALANCER_MAX_SENDING
sharding.rebalancer_mode

Since: 3.1.0

Configure how a rebalancer is selected:

  • auto (default): if there are no replica sets with the rebalancer sharding role (sharding.roles), a replica set with the rebalancer is selected automatically among all replica sets.
  • manual: one of the replica sets should have the rebalancer sharding role. The rebalancer is in this replica set.
  • off: rebalancing is turned off regardless of whether a replica set with the rebalancer sharding role exists or not.

Примечание

This option should be defined at the global level.


Type: string
Default: „auto“
Environment variable: TT_SHARDING_REBALANCER_MODE
sharding.roles

Roles of a replica set in regard to sharding. A replica set can have the following roles:

  • router: a replica set acts as a router.
  • storage: a replica set acts as a storage.
  • rebalancer: a replica set acts as a rebalancer.

The rebalancer role is optional. If it is not specified, a rebalancer is selected automatically from the master instances of replica sets.

There can be at most one replica set with the rebalancer role. Additionally, this replica set should have a storage role.

Example

replicasets:
  storage-a:
    sharding:
      roles: [storage, rebalancer]

See also: Sharding roles

Примечание

sharding.roles can be specified at the replica set level or higher.


Type: array
Default: nil
Environment variable: TT_SHARDING_ROLES
sharding.sched_move_quota

A scheduler’s bucket move quota used by the rebalancer.

sched_move_quota defines how many bucket moves can be done in a row if there are pending storage refs. Then, bucket moves are blocked and a router continues making map-reduce requests.

See also: sharding.sched_ref_quota

Примечание

This option should be defined at the global level.


Type: number
Default: 1
Environment variable: TT_SHARDING_SCHED_MOVE_QUOTA
sharding.sched_ref_quota

A scheduler’s storage ref quota used by a router’s map-reduce API. For example, the vshard.router.map_callrw() function implements consistent map-reduce over the entire cluster.

sched_ref_quota defines how many storage refs, therefore map-reduce requests, can be executed on the storage in a row if there are pending bucket moves. Then, storage refs are blocked and the rebalancer continues bucket moves.

See also: sharding.sched_move_quota

Примечание

This option should be defined at the global level.


Type: number
Default: 300
Environment variable: TT_SHARDING_SCHED_REF_QUOTA
sharding.shard_index

The name or ID of a TREE index over the bucket id. Spaces without this index do not participate in a sharded Tarantool cluster and can be used as regular spaces if needed. It is necessary to specify the first part of the index, other parts are optional.

Примечание

This option should be defined at the global level.

See also: Data definition


Type: string
Default: „bucket_id“
Environment variable: TT_SHARDING_SHARD_INDEX
sharding.sync_timeout

The timeout to wait for synchronization of the old master with replicas before demotion. Used when switching a master or when manually calling the sync() function.

Примечание

This option should be defined at the global level.


Type: number
Default: 1
Environment variable: TT_SHARDING_SYNC_TIMEOUT
sharding.weight

Since: 3.1.0

The relative amount of data that a replica set can store. Learn more at Вес набора реплик.

Примечание

sharding.weight can be specified at the replica set level.


Type: number
Default: 1
Environment variable: TT_SHARDING_WEIGHT
sharding.zone

A zone that can be set for routers and replicas. This allows sending read-only requests not only to a master instance but to any available replica that is the nearest to the router.

Примечание

sharding.zone can be specified at any level.


Type: integer
Default: nil
Environment variable: TT_SHARDING_ZONE

snapshot

The snapshot section defines configuration parameters related to the snapshot files. To learn more about the snapshots“ configuration, check the Persistence page.

Примечание

snapshot can be defined in any scope.

snapshot.dir

A directory where memtx stores snapshot (.snap) files. A relative path in this option is interpreted as relative to process.work_dir.

By default, snapshots and WAL files are stored in the same directory. However, you can set different values for the snapshot.dir and wal.dir options to store them on different physical disks for performance matters.


Type: string
Default: „var/lib/{{ instance_name }}“
Environment variable: TT_SNAPSHOT_DIR
snapshot.snap_io_rate_limit

Reduce the throttling effect of box.snapshot() on INSERT/UPDATE/DELETE performance by setting a limit on how many megabytes per second it can write to disk. The same can be achieved by splitting wal.dir and snapshot.dir locations and moving snapshots to a separate disk. The limit also affects what box.stat.vinyl().regulator may show for the write rate of dumps to .run and .index files.


Type: number
Default: box.NULL
Environment variable: TT_SNAPSHOT_SNAP_IO_RATE_LIMIT
snapshot.count

The maximum number of snapshots that are stored in the snapshot.dir directory. If the number of snapshots after creating a new one exceeds this value, the Tarantool garbage collector deletes old snapshots. If snapshot.count is set to zero, the garbage collector does not delete old snapshots.

Example

In the example, the checkpoint daemon creates a snapshot every two hours until it has created three snapshots. After creating a new snapshot (the fourth one), the oldest snapshot and any associated write-ahead-log files are deleted.

snapshot:
  by:
    interval: 7200
  count: 3

Примечание

Snapshots will not be deleted if replication is ongoing and the file has not been relayed to a replica. Therefore, snapshot.count has no effect unless all replicas are alive.


Type: integer
Default: 2
Environment variable: TT_SNAPSHOT_COUNT

snapshot.by.*

snapshot.by.interval

The interval in seconds between actions by the checkpoint daemon. If the option is set to a value greater than zero, and there is activity that causes change to a database, then the checkpoint daemon calls box.snapshot() every snapshot.by.interval seconds, creating a new snapshot file each time. If the option is set to zero, the checkpoint daemon is disabled.

Example

In the example, the checkpoint daemon creates a new database snapshot every two hours, if there is activity.

by:
  interval: 7200

Type: number
Default: 3600
Environment variable: TT_SNAPSHOT_BY_INTERVAL
snapshot.by.wal_size

The threshold for the total size in bytes for all WAL files created since the last snapshot taken. Once the configured threshold is exceeded, the WAL thread notifies the checkpoint daemon that it must make a new snapshot and delete old WAL files.


Type: integer
Default: 10^18
Environment variable: TT_SNAPSHOT_BY_WAL_SIZE

sql

The sql section defines configuration parameters related to SQL.

Примечание

sql can be defined in any scope.

sql.cache_size

The maximum cache size (in bytes) for all SQL prepared statements. To see the actual cache size, use box.info.sql().cache.size.


Type: integer
Default: 5242880
Environment variable: TT_SQL_CACHE_SIZE

vinyl

The vinyl section defines configuration parameters related to the vinyl storage engine.

Примечание

vinyl can be defined in any scope.

vinyl.bloom_fpr

A bloom filter’s false positive rate – the suitable probability of the bloom filter to give a wrong result. The vinyl.bloom_fpr setting is a default value for the bloom_fpr option passed to space_object:create_index().


Type: number
Default: 0.05
Environment variable: TT_VINYL_BLOOM_FPR
vinyl.cache

The cache size for the vinyl storage engine. The cache can be resized dynamically.


Type: integer
Default: 128 * 1024 * 1024
Environment variable: TT_VINYL_CACHE
vinyl.defer_deletes

Enable the deferred DELETE optimization in vinyl. It was disabled by default since Tarantool version 2.10 to avoid possible performance degradation of secondary index reads.


Type: boolean
Default: false
Environment variable: TT_VINYL_DEFER_DELETES
vinyl.dir

A directory where vinyl files or subdirectories will be stored.

This option may contain a relative file path. In this case, it is interpreted as relative to process.work_dir.


Type: string
Default: „var/lib/{{ instance_name }}“
Environment variable: TT_VINYL_DIR
vinyl.max_tuple_size

The size of the largest allocation unit, for the vinyl storage engine. It can be increased if it is necessary to store large tuples.


Type: integer
Default: 1024 * 1024
Environment variable: TT_VINYL_MAX_TUPLE_SIZE
vinyl.memory

The maximum number of in-memory bytes that vinyl uses.


Type: integer
Default: 128 * 1024 * 1024
Environment variable: TT_VINYL_MEMORY
vinyl.page_size

The page size. A page is a read/write unit for vinyl disk operations. The vinyl.page_size setting is a default value for the page_size option passed to space_object:create_index().


Type: integer
Default: 8 * 1024
Environment variable: TT_VINYL_PAGE_SIZE
vinyl.range_size

The default maximum range size for a vinyl index, in bytes. The maximum range size affects the decision of whether to split a range.

If vinyl.range_size is specified (but the value is not null or 0), then it is used as the default value for the range_size option passed to space_object:create_index().

If vinyl.range_size is not specified (or is explicitly set to null or 0), and range_size is not specified when the index is created, then Tarantool sets a value later depending on performance considerations. To see the actual value, use index_object:stat().range_size.


Type: integer
Default: box.NULL (means that an effective default is determined in runtime)
Environment variable: TT_VINYL_RANGE_SIZE
vinyl.read_threads

The maximum number of read threads that vinyl can use for concurrent operations, such as I/O and compression.


Type: integer
Default: 1
Environment variable: TT_VINYL_READ_THREADS
vinyl.run_count_per_level

The maximum number of runs per level in the vinyl LSM tree. If this number is exceeded, a new level is created. The vinyl.run_count_per_level setting is a default value for the run_count_per_level option passed to space_object:create_index().


Type: integer
Default: 2
Environment variable: TT_VINYL_RUN_COUNT_PER_LEVEL
vinyl.run_size_ratio

The ratio between the sizes of different levels in the LSM tree. The vinyl.run_size_ratio setting is a default value for the run_size_ratio option passed to space_object:create_index().


Type: number
Default: 3.5
Environment variable: TT_VINYL_RUN_SIZE_RATIO
vinyl.timeout

The vinyl storage engine has a scheduler that performs compaction. When vinyl is low on available memory, the compaction scheduler may be unable to keep up with incoming update requests. In that situation, queries may time out after vinyl.timeout seconds. This should rarely occur, since normally vinyl throttles inserts when it is running low on compaction bandwidth. Compaction can also be initiated manually with index_object:compact().


Type: integer
Default: 60
Environment variable: TT_VINYL_TIMEOUT
vinyl.write_threads

The maximum number of write threads that vinyl can use for some concurrent operations, such as I/O and compression.


Type: integer
Default: 4
Environment variable: TT_VINYL_WRITE_THREADS

wal

The wal section defines configuration parameters related to write-ahead log. To learn more about the WAL configuration, check the Persistence page.

Примечание

wal can be defined in any scope.

wal.cleanup_delay

The delay in seconds used to prevent the Tarantool garbage collector from immediately removing write-ahead log files after a node restart. This delay eliminates possible erroneous situations when the master deletes WALs needed by replicas after restart. As a consequence, replicas sync with the master faster after its restart and don’t need to download all the data again. Once all the nodes in the replica set are up and running, a scheduled garbage collection is started again even if wal.cleanup_delay has not expired.

Примечание

The option has no effect on nodes running as anonymous replicas.

See also: wal.retention_period


Type: number
Default: 14400
Environment variable: TT_WAL_CLEANUP_DELAY
wal.dir

A directory where write-ahead log (.xlog) files are stored. A relative path in this option is interpreted as relative to process.work_dir.

By default, WAL files and snapshots are stored in the same directory. However, you can set different values for the wal.dir and snapshot.dir options to store them on different physical disks for performance matters.


Type: string
Default: „var/lib/{{ instance_name }}“
Environment variable: TT_WAL_DIR
wal.dir_rescan_delay

The time interval in seconds between periodic scans of the write-ahead-log file directory, when checking for changes to write-ahead-log files for the sake of replication or hot standby.


Type: number
Default: 2
Environment variable: TT_WAL_DIR_RESCAN_DELAY
wal.max_size

The maximum number of bytes in a single write-ahead log file. When a request would cause an .xlog file to become larger than wal.max_size, Tarantool creates a new WAL file.


Type: integer
Default: 268435456
Environment variable: TT_WAL_MAX_SIZE
wal.mode

Specify fiber-WAL-disk synchronization mode as:

  • none: write-ahead log is not maintained. A node with wal.mode set to none can’t be a replication master.
  • write: fibers wait for their data to be written to the write-ahead log (no fsync(2)).
  • fsync: fibers wait for their data, fsync(2) follows each write(2).

Type: string
Default: „write“
Environment variable: TT_WAL_MODE
wal.queue_max_size

The size of the queue in bytes used by a replica to submit new transactions to a write-ahead log (WAL). This option helps limit the rate at which a replica submits transactions to the WAL.

Limiting the queue size might be useful when a replica is trying to sync with a master and reads new transactions faster than writing them to the WAL.

Примечание

You might consider increasing the wal.queue_max_size value in case of large tuples (approximately one megabyte or larger).


Type: integer
Default: 16777216
Environment variable: TT_WAL_QUEUE_MAX_SIZE
wal.retention_period

Since: 3.1.0 (Enterprise Edition only)

The delay in seconds used to prevent the Tarantool garbage collector from removing a write-ahead log file after it has been closed. If a node is restarted, wal.retention_period counts down from the last modification time of the write-ahead log file.

The garbage collector doesn’t track write-ahead logs that are to be relayed to anonymous replicas, such as:

  • Anonymous replicas added as a part of a cluster configuration (see replication.anon).
  • CDC (Change Data Capture) that retrieves data using anonymous replication.

In case of a replica or CDC downtime, the required write-ahead logs can be removed. As a result, such a replica needs to be rebootstrapped. You can use wal.retention_period to prevent such issues.

Note that wal.cleanup_delay option also sets the delay used to prevent the Tarantool garbage collector from removing write-ahead logs. The difference is that the garbage collector doesn’t take into account wal.cleanup_delay if all the nodes in the replica set are up and running, which may lead to the removal of the required write-ahead logs.

Примечание

box.info.gc().wal_retention_vclock can be used to get a vclock value of the oldest write-ahead log protected by wal.retention_period.


Type: number
Default: 0
Environment variable: TT_WAL_RETENTION_PERIOD

wal.ext.*

Enterprise Edition

Configuring wal.ext.* parameters is available in the Enterprise Edition only.

This section describes options related to WAL extensions.

wal.ext.new

Enable storing a new tuple for each CRUD operation performed. The option is in effect for all spaces. To adjust the option for specific spaces, use the wal.ext.spaces option.


Type: boolean
Default: false
Environment variable: TT_WAL_EXT_NEW
wal.ext.old

Enable storing an old tuple for each CRUD operation performed. The option is in effect for all spaces. To adjust the option for specific spaces, use the wal.ext.spaces option.


Type: boolean
Default: false
Environment variable: TT_WAL_EXT_OLD
wal.ext.spaces

Enable or disable storing an old and new tuple in the WAL record for a given space explicitly. The configuration for specific spaces has priority over the configuration in the wal.ext.new and wal.ext.old options.

The option is a key-value pair:

  • The key is a space name (string).
  • The value is a table that includes two optional boolean options: old and new. The format and the default value of these options are described in wal.ext.old and wal.ext.new.

Example

In the example, only new tuples are added to the log for the bands space.

ext:
  new: true
  old: true
  spaces:
    bands:
      old: false

Type: map
Default: nil
Environment variable: TT_WAL_EXT_SPACES

Configuration reference (box.cfg)

Примечание

Starting with the 3.0 version, the recommended way of configuring Tarantool is using a configuration file. Configuring Tarantool in code is considered a legacy approach.

This topic describes all configuration parameters that can be specified in code using the box.cfg API.

Базовые параметры

background

Since version 1.6.2.

Run the server as a background task. The log and pid_file parameters must be non-null for this to work.

Важно

Do not enable the background mode for applications intended to run by the tt utility. For more information, see the tt start reference.


Тип: логический
По умолчанию: false (ложь)
Environment variable: TT_BACKGROUND
Динамический: нет
coredump

Create coredump files.

Usually, an administrator needs to call ulimit -c unlimited (or set corresponding options in systemd’s unit file) before running a Tarantool process to get core dumps. If coredump is enabled, Tarantool sets the corresponding resource limit by itself and the administrator doesn’t need to call ulimit -c unlimited (see man 3 setrlimit).

This option also sets the state of the dumpable attribute, which is enabled by default, but may be dropped in some circumstances (according to man 2 prctl, see PR_SET_DUMPABLE).


Тип: логический
Environment variable: TT_COREDUMP
По умолчанию: false (ложь)
Динамический: нет
custom_proc_title

Since version 1.6.7.

Add the given string to the server’s process title (what’s shown in the COMMAND column for ps -ef and top -c commands).

Например, как правило, ps -ef показывает процесс Tarantool-сервера так:

$ ps -ef | grep tarantool
1000     14939 14188  1 10:53 pts/2    00:00:13 tarantool <running>

Но если указан конфигурационный параметр custom_proc_title='sessions', вывод выглядит так:

$ ps -ef | grep tarantool
1000     14939 14188  1 10:53 pts/2    00:00:16 tarantool <running>: sessions

Тип: строка
По умолчанию: null
Environment variable: TT_CUSTOM_PROC_TITLE
Динамический: да
listen

Since version 1.6.4.

The read/write data port number or URI (Universal Resource Identifier) string. Has no default value, so must be specified if connections occur from the remote clients that don’t use the «admin port». Connections made with listen = URI are called «binary port» or «binary protocol» connections.

Как правило, используется значение 3301.

box.cfg { listen = 3301 }

box.cfg { listen = "127.0.0.1:3301" }

Примечание

Реплика также привязана на этот порт и принимает соединения, но эти соединения служат только для чтения до тех пор, пока реплика не станет мастером.

Starting from version 2.10.0, you can specify several URIs, and the port number is always stored as an integer value.


Тип: целое число или строка
По умолчанию: null
Environment variable: TT_LISTEN
Динамический: да
memtx_dir

Since version 1.7.4.

A directory where memtx stores snapshot (.snap) files. A relative path in this option is interpreted as relative to work_dir.

By default, snapshots and WAL files are stored in the same directory. However, you can set different values for the memtx_dir and wal_dir options to store them on different physical disks for performance matters.


Тип: строка
По умолчанию: «.»
Environment variable: TT_MEMTX_DIR
Динамический: нет
pid_file

Since version 1.4.9.

Store the process id in this file. Can be relative to work_dir. A typical value is “tarantool.pid”.


Тип: строка
По умолчанию: null
Environment variable: TT_PID_FILE
Динамический: нет
read_only

Since version 1.7.1.

Say box.cfg{read_only=true...} to put the server instance in read-only mode. After this, any requests that try to change persistent data will fail with error ER_READONLY. Read-only mode should be used for master-replica replication. Read-only mode does not affect data-change requests for spaces defined as temporary. Although read-only mode prevents the server from writing to the WAL, it does not prevent writing diagnostics with the log module.


Тип: логический
По умолчанию: false (ложь)
Environment variable: TT_READ_ONLY
Динамический: да

Setting read_only == true affects spaces differently depending on the options that were used during box.schema.space.create, as summarized by this chart:

Характеристика Можно создать? Допускает запись? Реплицируется? Сохраняется?
(по умолчанию) нет нет да да
temporary нет да нет нет
is_local нет да нет да
sql_cache_size

Since version 2.3.1.

The maximum number of bytes in the cache for SQL prepared statements. (The number of bytes that are actually used can be seen with box.info.sql().cache.size.)


Тип: число
По умолчанию: 5242880
Environment variable: TT_SQL_CACHE_SIZE
Динамический: да
vinyl_dir

Since version 1.7.1.

A directory where vinyl files or subdirectories will be stored. Can be relative to work_dir. If not specified, defaults to work_dir.


Тип: строка
По умолчанию: «.»
Environment variable: TT_VINYL_DIR
Динамический: нет
vinyl_timeout

Since version 1.7.5.

The vinyl storage engine has a scheduler which does compaction. When vinyl is low on available memory, the compaction scheduler may be unable to keep up with incoming update requests. In that situation, queries may time out after vinyl_timeout seconds. This should rarely occur, since normally vinyl would throttle inserts when it is running low on compaction bandwidth. Compaction can also be ordered manually with index_object:compact().


Тип: число с плавающей запятой
По умолчанию: 60
Environment variable: TT_VINYL_TIMEOUT
Динамический: да
username

Since version 1.4.9.

UNIX user name to switch to after start.


Тип: строка
По умолчанию: null
Environment variable: TT_USERNAME
Динамический: нет
wal_dir

Since version 1.6.2.

A directory where write-ahead log (.xlog) files are stored. A relative path in this option is interpreted as relative to work_dir.

By default, WAL files and snapshots are stored in the same directory. However, you can set different values for the wal_dir and memtx_dir options to store them on different physical disks for performance matters.


Тип: строка
По умолчанию: «.»
Environment variable: TT_WAL_DIR
Динамический: нет
work_dir

Since version 1.4.9.

A directory where database working files will be stored. The server instance switches to work_dir with chdir(2) after start. Can be relative to the current directory. If not specified, defaults to the current directory. Other directory parameters may be relative to work_dir, for example:

box.cfg{
    work_dir = '/home/user/A',
    wal_dir = 'B',
    memtx_dir = 'C'
}

поместит xlog-файлы в /home/user/A/B, файлы снимков в /home/user/A/C, а все остальные файлы или поддиректории в /home/user/A.


Тип: строка
По умолчанию: null
Environment variable: TT_WORK_DIR
Динамический: нет
worker_pool_threads

Since version 1.7.5.

The maximum number of threads to use during execution of certain internal processes (currently socket.getaddrinfo() and coio_call()).


Тип: целое число
По умолчанию: 4
Environment variable: TT_WORKER_POOL_THREADS
Динамический: да
strip_core

Since version 2.2.2.

Whether coredump files should include memory allocated for tuples. (This can be large if Tarantool runs under heavy load.) Setting to true means «do not include». In an older version of Tarantool the default value of this parameter was false.


Тип: логический
По умолчанию: true
Environment variable: TT_STRIP_CORE
Динамический: нет
memtx_use_mvcc_engine

Since version 2.6.1.

Enable transactional manager if set to true.


Тип: логический
По умолчанию: false (ложь)
Environment variable: TT_MEMTX_USE_MVCC_ENGINE
Динамический: нет

Настройка хранения

memtx_memory

Since version 1.7.4.

How much memory Tarantool allocates to store tuples. When the limit is reached, INSERT or UPDATE requests begin failing with error ER_MEMORY_ISSUE. The server does not go beyond the memtx_memory limit to allocate tuples, but there is additional memory used to store indexes and connection information.


Тип: число с плавающей запятой
По умолчанию: 256 * 1024 * 1024 = 268435456 байтов
Minimum: 33554432 bytes (32 MB)
Environment variable: TT_MEMTX_MEMORY
Dynamic: yes but it cannot be decreased
memtx_max_tuple_size

Since version 1.7.4.

Size of the largest allocation unit, for the memtx storage engine. It can be increased if it is necessary to store large tuples.


Тип: целое число
По умолчанию: 1024 * 1024 = 1048576 байтов
Environment variable: TT_MEMTX_MAX_TUPLE_SIZE
Динамический: да
memtx_min_tuple_size

Since version 1.7.4.

Size of the smallest allocation unit. It can be decreased if most of the tuples are very small.


Тип: целое число
По умолчанию: 16 байтов
Possible values: between 8 and 1048280 inclusive
Environment variable: TT_MEMTX_MIN_TUPLE_SIZE
Динамический: нет
memtx_allocator

Since version 2.10.0.

Specify the allocator that manages memory for memtx tuples. Possible values:

  • system – the memory is allocated as needed, checking that the quota is not exceeded. THe allocator is based on the malloc function.
  • small – a slab allocator. The allocator repeatedly uses a memory block to allocate objects of the same type. Note that this allocator is prone to unresolvable fragmentation on specific workloads, so you can switch to system in such cases.

Тип: строка
Default: „small“
Environment variable: TT_MEMTX_ALLOCATOR
Динамический: нет
memtx_sort_threads

Since: 3.0.0.

The number of threads from the thread pool used to sort keys of secondary indexes on loading a memtx database. The minimum value is 1, the maximum value is 256. The default is to use all available cores.

Примечание

Since 3.0.0, this option replaces the approach when OpenMP threads are used to parallelize sorting. For backward compatibility, the OMP_NUM_THREADS environment variable is taken into account to set the number of sorting threads.


Тип: целое число
Default: box.NULL
Environment variable: TT_MEMTX_SORT_THREADS
Динамический: нет
slab_alloc_factor

The multiplier for computing the sizes of memory chunks that tuples are stored in. A lower value may result in less wasted memory depending on the total amount of memory available and the distribution of item sizes.

See also: slab_alloc_granularity


Тип: число с плавающей запятой
Default: 1.05
Possible values: between 1 and 2 inclusive
Environment variable: TT_SLAB_ALLOC_FACTOR
Динамический: нет
slab_alloc_granularity

Since version 2.8.1.

Specify the granularity (in bytes) of memory allocation in the small allocator. The memtx.slab_alloc_granularity value should meet the following conditions:

  • The value is a power of two.
  • The value is greater than or equal to 4.

Below are few recommendations on how to adjust the memtx.slab_alloc_granularity option:

  • If the tuples in space are small and have about the same size, set the option to 4 bytes to save memory.
  • If the tuples are different-sized, increase the option value to allocate tuples from the same mempool (memory pool).

See also: slab_alloc_factor


Тип: число
Default: 8 bytes
Environment variable: TT_SLAB_ALLOC_GRANULARITY
Динамический: нет
vinyl_bloom_fpr

Since version 1.7.4.

Bloom filter false positive rate – the suitable probability of the bloom filter to give a wrong result. The vinyl_bloom_fpr setting is a default value for one of the options in the Options for space_object:create_index() chart.


Тип: число с плавающей запятой
По умолчанию: 0.05
Environment variable: TT_VINYL_BLOOM_FPR
Динамический: нет
vinyl_cache

Для версий от 1.7.4. и выше. Размер кэша для движка базы данных vinyl. Размер кэша можно изменить динамически.


Тип: целое число
По умолчанию: 128 * 1024 * 1024 = 134217728 байтов
Environment variable: TT_VINYL_CACHE
Динамический: да
vinyl_max_tuple_size

Since version 1.7.5.

Size of the largest allocation unit, for the vinyl storage engine. It can be increased if it is necessary to store large tuples. See also: memtx_max_tuple_size.


Тип: целое число
По умолчанию: 1024 * 1024 = 1048576 байтов
Environment variable: TT_VINYL_MAX_TUPLE_SIZE
Динамический: нет
vinyl_memory

Since version 1.7.4.

The maximum number of in-memory bytes that vinyl uses.


Тип: целое число
По умолчанию: 128 * 1024 * 1024 = 134217728 байтов
Environment variable: TT_VINYL_MEMORY
Dynamic: yes but it cannot be decreased
vinyl_page_size

Since version 1.7.4.

Page size. Page is a read/write unit for vinyl disk operations. The vinyl_page_size setting is a default value for one of the options in the Options for space_object:create_index() chart.


Тип: целое число
По умолчанию: 8 * 1024 = 8192 байтов
Environment variable: TT_VINYL_PAGE_SIZE
Динамический: нет
vinyl_range_size

Since version 1.7.4.

The default maximum range size for a vinyl index, in bytes. The maximum range size affects the decision whether to split a range.

Если vinyl_range_size содержит не нулевое значение nil и не 0, это значение используется в качестве значения по умолчанию для параметра range_size в таблице Параметры space_object:create_index().

Если vinyl_range_size содержит нулевое значение nil или 0, а параметр range_size не задан при создании индекса, то Tarantool сам задает это значение позднее в результате оценки производительности. Чтобы узнать текущее значение, используйте index_object:stat().range_size.

До версии Tarantool 1.10.2 значение vinyl_range_size по умолчанию было 1073741824.


Тип: целое число
По умолчанию: nil
Environment variable: TT_VINYL_RANGE_SIZE
Динамический: нет
vinyl_run_count_per_level

Since version 1.7.4.

The maximal number of runs per level in vinyl LSM tree. If this number is exceeded, a new level is created. The vinyl_run_count_per_level setting is a default value for one of the options in the Options for space_object:create_index() chart.


Тип: целое число
По умолчанию: 2
Environment variable: TT_VINYL_RUN_COUNT_PER_LEVEL
Динамический: нет
vinyl_run_size_ratio

Since version 1.7.4.

Ratio between the sizes of different levels in the LSM tree. The vinyl_run_size_ratio setting is a default value for one of the options in the Options for space_object:create_index() chart.


Тип: число с плавающей запятой
По умолчанию: 3.5
Environment variable: TT_VINYL_RUN_SIZE_RATIO
Динамический: нет
vinyl_read_threads

Since version 1.7.5.

The maximum number of read threads that vinyl can use for some concurrent operations, such as I/O and compression.


Тип: целое число
По умолчанию: 1
Environment variable: TT_VINYL_READ_THREADS
Динамический: нет
vinyl_write_threads

Since version 1.7.5.

The maximum number of write threads that vinyl can use for some concurrent operations, such as I/O and compression.


Тип: целое число
По умолчанию: 4
Environment variable: TT_VINYL_WRITE_THREADS
Динамический: нет

Демон создания контрольных точек

Checkpoint daemon

The checkpoint daemon (snapshot daemon) is a constantly running fiber. The checkpoint daemon creates a schedule for the periodic snapshot creation based on the configuration options and the speed of file size growth. If enabled, the daemon makes new snapshot (.snap) files according to this schedule.

The work of the checkpoint daemon is based on the following configuration options:

If necessary, the checkpoint daemon also activates the Tarantool garbage collector that deletes old snapshots and WAL files.

Сборщик мусора Tarantool

Tarantool garbage collector can be activated by the checkpoint daemon. The garbage collector tracks the snapshots that are to be relayed to a replica or needed by other consumers. When the files are no longer needed, Tarantool garbage collector deletes them.

Примечание

The garbage collector called by the checkpoint daemon is distinct from the Lua garbage collector which is for Lua objects, and distinct from the Tarantool garbage collector that specializes in handling shard buckets.

This garbage collector is called as follows:

If an old snapshot file is deleted, the Tarantool garbage collector also deletes any write-ahead log (.xlog) files that meet the following conditions:

Tarantool garbage collector also deletes obsolete vinyl .run files.

Tarantool garbage collector doesn’t delete a file in the following cases:

checkpoint_interval

Since version 1.7.4.

The interval in seconds between actions by the checkpoint daemon. If the option is set to a value greater than zero, and there is activity that causes change to a database, then the checkpoint daemon calls box.snapshot() every checkpoint_interval seconds, creating a new snapshot file each time. If the option is set to zero, the checkpoint daemon is disabled.

Example

box.cfg{ checkpoint_interval = 7200 }

In the example, the checkpoint daemon creates a new database snapshot every two hours, if there is activity.


Тип: целое число
По умолчанию: 3600 (один час)
Environment variable: TT_CHECKPOINT_INTERVAL
Динамический: да
checkpoint_count

Since version 1.7.4.

The maximum number of snapshots that are stored in the memtx_dir directory. If the number of snapshots after creating a new one exceeds this value, the Tarantool garbage collector deletes old snapshots. If the option is set to zero, the garbage collector does not delete old snapshots.

Example

box.cfg{
    checkpoint_interval = 7200,
    checkpoint_count  = 3
}

In the example, the checkpoint daemon creates a new snapshot every two hours until it has created three snapshots. After creating a new snapshot (the fourth one), the oldest snapshot and any associated write-ahead-log files are deleted.

Примечание

Snapshots will not be deleted if replication is ongoing and the file has not been relayed to a replica. Therefore, checkpoint_count has no effect unless all replicas are alive.


Тип: целое число
По умолчанию: 2
Environment variable: TT_CHECKPOINT_COUNT
Динамический: да
checkpoint_wal_threshold

Since version 2.1.2.

The threshold for the total size in bytes for all WAL files created since the last checkpoint. Once the configured threshold is exceeded, the WAL thread notifies the checkpoint daemon that it must make a new checkpoint and delete old WAL files.

Этот параметр позволяет администраторам справиться с проблемой, которая может возникнуть при вычислении объема дискового пространства для раздела, содержащего файлы WAL.


Тип: целое число
По умолчанию: 10^18 (большое число: можно считать, что предела нет)
Environment variable: TT_CHECKPOINT_WAL_THRESHOLD
Динамический: да

Записи в бинарный журнал и создание снимков

force_recovery

Since version 1.7.4.

If force_recovery equals true, Tarantool tries to continue if there is an error while reading a snapshot file (at server instance start) or a write-ahead log file (at server instance start or when applying an update at a replica): skips invalid records, reads as much data as possible and lets the process finish with a warning. Users can prevent the error from recurring by writing to the database and executing box.snapshot().

В остальных случаях Tarantool прерывает восстановление на ошибке чтения.


Тип: логический
По умолчанию: false (ложь)
Environment variable: TT_FORCE_RECOVERY
Динамический: нет
wal_max_size

Since version 1.7.4.

The maximum number of bytes in a single write-ahead log file. When a request would cause an .xlog file to become larger than wal_max_size, Tarantool creates a new WAL file.


Тип: целое число
По умолчанию: 268435456 (256 * 1024 * 1024) байтов
Environment variable: TT_WAL_MAX_SIZE
Динамический: нет
snap_io_rate_limit

Since version 1.4.9.

Reduce the throttling effect of box.snapshot() on INSERT/UPDATE/DELETE performance by setting a limit on how many megabytes per second it can write to disk. The same can be achieved by splitting wal_dir and memtx_dir locations and moving snapshots to a separate disk. The limit also affects what box.stat.vinyl().regulator may show for the write rate of dumps to .run and .index files.


Тип: число с плавающей запятой
По умолчанию: null
Environment variable: TT_SNAP_IO_RATE_LIMIT
Динамический: да
wal_mode

Since version 1.6.2.

Specify fiber-WAL-disk synchronization mode as:

  • none: write-ahead log is not maintained. A node with wal_mode set to none can’t be a replication master.
  • write: fibers wait for their data to be written to the write-ahead log (no fsync(2)).
  • fsync: fibers wait for their data, fsync(2) follows each write(2).

Тип: строка
По умолчанию: «write»
Environment variable: TT_WAL_MODE
Динамический: нет
wal_dir_rescan_delay

Since version 1.6.2.

The time interval in seconds between periodic scans of the write-ahead-log file directory, when checking for changes to write-ahead-log files for the sake of replication or hot standby.


Тип: число с плавающей запятой
По умолчанию: 2
Environment variable: TT_WAL_DIR_RESCAN_DELAY
Динамический: нет
wal_queue_max_size

Since version 2.8.1.

The size of the queue (in bytes) used by a replica to submit new transactions to a write-ahead log (WAL). This option helps limit the rate at which a replica submits transactions to the WAL. Limiting the queue size might be useful when a replica is trying to sync with a master and reads new transactions faster than writing them to the WAL.

Примечание

You might consider increasing the wal_queue_max_size value in case of large tuples (approximately one megabyte or larger).


Тип: число
Default: 16777216 bytes
Environment variable: TT_WAL_QUEUE_MAX_SIZE
Динамический: да
wal_cleanup_delay

Since version 2.6.3.

The delay in seconds used to prevent the Tarantool garbage collector from immediately removing write-ahead log files after a node restart. This delay eliminates possible erroneous situations when the master deletes WALs needed by replicas after restart. As a consequence, replicas sync with the master faster after its restart and don’t need to download all the data again. Once all the nodes in the replica set are up and running, a scheduled garbage collection is started again even if wal_cleanup_delay has not expired.

Примечание

The wal_cleanup_delay option has no effect on nodes running as anonymous replicas.


Тип: число
Default: 14400 seconds
Environment variable: TT_WAL_CLEANUP_DELAY
Динамический: да
wal_ext

Since version 2.11.0.

(Enterprise Edition only) Allows you to add auxiliary information to each write-ahead log record. For example, you can enable storing an old and new tuple for each CRUD operation performed. This information might be helpful for implementing a CDC (Change Data Capture) utility that transforms a data replication stream.

You can enable storing old and new tuples as follows:

  • Set the old and new options to true to store old and new tuples in a write-ahead log for all spaces.

    box.cfg {
    wal_ext = { old = true, new = true }
}

  • To adjust these options for specific spaces, use the spaces option.

    box.cfg {
    wal_ext = {
        old = true, new = true,
        spaces = {
            space1 = { old = false },
            space2 = { new = false }
        }
    }
}

    The configuration for specific spaces has priority over the global configuration, so only new tuples are added to the log for space1 and only old tuples for space2.

Note that records with additional fields are replicated as follows:

  • If a replica doesn’t support the extended format configured on a master, auxiliary fields are skipped.
  • If a replica and master have different configurations for WAL records, the master’s configuration is ignored.

Type: map
По умолчанию: nil
Environment variable: TT_WAL_EXT
Динамический: да
secure_erasing

Since version 3.0.0.

(Enterprise Edition only) If true, forces Tarantool to overwrite a data file a few times before deletion to render recovery of a deleted file impossible. The option applies to both .xlog and .snap files as well as Vinyl data files.


Тип: логический
По умолчанию: false (ложь)
Environment variable: TT_SECURE_ERASING
Динамический: да

Горячее резервирование

hot_standby

Since version 1.7.4.

Whether to start the server in hot standby mode.

Горячее резервирование – это функция, которая обеспечивает простое восстановление после отказа без репликации.

Предполагается, что есть два экземпляра сервера, использующих одну и ту же конфигурацию. Первый из них станет «основным» экземпляром. Тот, который запускается вторым, станет «резервным» экземпляром.

Чтобы создать резервный экземпляр, запустите второй экземпляр Tarantool-сервера на том же компьютере с теми же настройками конфигурации box.cfg – включая одинаковые директории и ненулевые URI – и с дополнительной настройкой конфигурации hot_standby = true. В ближайшее время вы увидите уведомление, которое заканчивается словами I> Entering hot standby mode (вход в режим горячего резервирования). Всё в порядке – это означает, что резервный экземпляр готов взять работу на себя, если основной экземпляр прекратит работу.

Резервный экземпляр начнет инициализацию и попытается заблокировать wal_dir, но не сможет, поскольку директория wal_dir заблокирована основным экземпляром. Поэтому резервный экземпляр входит в цикл, выполняя чтение журнала упреждающей записи, в который записывает данные основной экземпляр (поэтому два экземпляра всегда синхронизированы), и пытаясь произвести блокировку. Если основной экземпляр по какой-либо причине прекращает работу, блокировка снимается. В таком случае резервный экземпляр сможет заблокировать директорию на себя, подключится по адресу для прослушивания и станет основным экземпляром. В ближайшее время вы увидите уведомление, которое заканчивается словами I> ready to accept requests (готов принимать запросы).

Таким образом, если основной экземпляр прекращает работу, время простоя отсутствует.

Функция горячего резервирования не работает:

  • если wal_dir_rescan_delay = большое число (в Mac OS и FreeBSD); на этих платформах цикл запрограммирован на повторение каждые wal_dir_rescan_delay секунд.
  • если wal_mode = „none“; будет работать только при wal_mode = 'write' или wal_mode = 'fsync'.
  • со спейсами, созданными на движке vinyl engine = „vinyl“; работает с движком memtx engine = 'memtx'.

Тип: логический
По умолчанию: false (ложь)
Environment variable: TT_HOT_STANDBY
Динамический: нет

Репликация

replication

Since version 1.7.4.

If replication is not an empty string, the instance is considered to be a Tarantool replica. The replica will try to connect to the master specified in replication with a URI (Universal Resource Identifier), for example:

konstantin:secret_password@tarantool.org:3301

Если в наборе реплик более одного источника репликации, укажите массив URI, например (замените „uri“ и „uri2“ в данном примере на рабочие URI):

box.cfg{ replication = { 'uri1', 'uri2' } }

Примечание

Starting from version 2.10.0, there is a number of other ways for specifying several URIs. See syntax examples.

If one of the URIs is «self» – that is, if one of the URIs is for the instance where box.cfg{} is being executed – then it is ignored. Thus, it is possible to use the same replication specification on multiple server instances, as shown in these examples.

По умолчанию, пользователем считается „guest“.

Реплика в режиме только для чтения не принимает запросы по изменению данных по порту для прослушивания.

Параметр replication является динамическим, то есть для входа в режим мастера необходимо просто присвоить параметру replication пустую строку и выполнить следующее:

box.cfg{ replication = новое-значение }


Тип: строка
По умолчанию: null
Environment variable: TT_REPLICATION
Динамический: да
replication_anon

Since version 2.3.1.

A Tarantool replica can be anonymous. This type of replica is read-only (but you still can write to temporary and replica-local spaces), and it isn’t present in the _cluster space.

Так как анонимная реплика не зарегистрирована в таблице _cluster, нет никаких ограничений для количества анонимных реплик в наборе: можно создавать их сколько угодно.

Чтобы сделать реплику анонимной, передайте опцию replication_anon=true в box.cfg и установите значение read_only равным true.

Попробуем создать анонимную реплику. Предположим, что у нас есть мастер с такой настройкой:

box.cfg{listen=3301}

и создан локальный спейс «loc»:

box.schema.space.create('loc', {is_local=true})
box.space.loc:create_index("pk")

Теперь, чтобы настроить анонимную реплику, нам нужно обратиться к box.cfg, как обычно.

box.cfg{replication_anon=true, read_only=true, replication=3301}

Как было сказано выше, replication_anon может быть true только вместе с read_only. Этот экземпляр получит снимок мастера и начнет следить за его изменениями. Он не получит id, поэтому его значение останется нулевым.

tarantool> box.info.id
---
- 0
...
tarantool> box.info.replication
---
- 1:
    id: 1
    uuid: 3c84f8d9-e34d-4651-969c-3d0ed214c60f
    lsn: 4
    upstream:
    status: follow
    idle: 0.6912029999985
    peer:
    lag: 0.00014615058898926
...

Теперь можно использовать реплику. Например, можно сделать вставку в локальный спейс:

tarantool> for i = 1,10 do
    > box.space.loc:insert{i}
    > end
---
...

Заметьте, что пока экземпляр анонимный, увеличится нулевая компонента его vclock:

tarantool> box.info.vclock
---
- {0: 10, 1: 4}
...

А теперь давайте сделаем анонимную реплику снова обычной:

tarantool> box.cfg{replication_anon=false}
2019-12-13 20:34:37.423 [71329] main I> assigned id 2 to replica 6a9c2ed2-b9e1-4c57-a0e8-51a46def7661
2019-12-13 20:34:37.424 [71329] main/102/interactive I> set 'replication_anon' configuration option to false
---
...

tarantool> 2019-12-13 20:34:37.424 [71329] main/117/applier/ I> subscribed
2019-12-13 20:34:37.424 [71329] main/117/applier/ I> remote vclock {1: 5} local vclock {0: 10, 1: 5}
2019-12-13 20:34:37.425 [71329] main/118/applierw/ C> leaving orphan mode

Эта реплика получила id равный 2. Мы можем снова сделать ее открытой на запись:

tarantool> box.cfg{read_only=false}
2019-12-13 20:35:46.392 [71329] main/102/interactive I> set 'read_only' configuration option to false
---
...

tarantool> box.schema.space.create('test')
---
- engine: memtx
before_replace: 'function: 0x01109f9dc8'
on_replace: 'function: 0x01109f9d90'
ck_constraint: []
field_count: 0
temporary: false
index: []
is_local: false
enabled: false
name: test
id: 513
- created
...

tarantool> box.info.vclock
---
- {0: 10, 1: 5, 2: 2}
...

Теперь, как и ожидалось, реплика отслеживает свои изменения во 2-й компоненте vclock. С этого момента она также может стать мастером репликации.

Замечания:

  • Нельзя реплицироваться от анонимной реплики.
  • Чтобы вернуть анонимный экземпляр к обычному состоянию, сначала запустите его как анонимный, а потом вызовите box.cfg{replication_anon=false}
  • Чтобы деанонимизация прошла успешно, экземпляр должен быть скопирован с какого-то экземпляра, открытого на запись, иначе он не может быть добавлен в таблицу _cluster.

Тип: логический
По умолчанию: false (ложь)
Environment variable: TT_REPLICATION_ANON
Динамический: да
bootstrap_leader

Since 3.0.0.

A bootstrap leader for a replica set. You can pass a bootstrap leader’s URI, UUID, or name.

To specify a bootstrap leader manually, you need to set bootstrap_strategy to config, for example:

box.cfg{
    bootstrap_strategy = 'config',
    bootstrap_leader = '127.0.0.1:3301',
    replication = {'127.0.0.1:3301'},
}

Тип: строка
По умолчанию: null
Environment variable: TT_BOOTSTRAP_LEADER
Динамический: да
bootstrap_strategy

Since 2.11.0.

Specify a strategy used to bootstrap a replica set. The following strategies are available:

  • auto: a node doesn’t boot if a half or more of other nodes in a replica set are not connected. For example, if the replication parameter contains 2 or 3 nodes, a node requires 2 connected instances. In the case of 4 or 5 nodes, at least 3 connected instances are required. Moreover, a bootstrap leader fails to boot unless every connected node has chosen it as a bootstrap leader.
  • config: use the specified node to bootstrap a replica set. To specify the bootstrap leader, use the bootstrap_leader option.
  • supervised: a bootstrap leader isn’t chosen automatically but should be appointed using box.ctl.make_bootstrap_leader() on the desired node.
  • legacy (deprecated since 2.11.0): a node requires the replication_connect_quorum number of other nodes to be connected. This option is added to keep the compatibility with the current versions of Cartridge and might be removed in the future.

Тип: строка
Default: auto
Environment variable: TT_BOOTSTRAP_STRATEGY
Динамический: да
replication_connect_timeout

Since version 1.9.0.

The number of seconds that a replica will wait when trying to connect to a master in a cluster. See orphan status for details.

This parameter is different from replication_timeout, which a master uses to disconnect a replica when the master receives no acknowledgments of heartbeat messages.


Тип: число с плавающей запятой
По умолчанию: 30
Environment variable: TT_REPLICATION_CONNECT_TIMEOUT
Динамический: да
replication_connect_quorum

Deprecated since 2.11.0.

This option is in effect if bootstrap_strategy is set to legacy.

Specify the number of nodes to be up and running to start a replica set. This parameter has effect during bootstrap or configuration update. Setting replication_connect_quorum to 0 makes Tarantool require no immediate reconnect only in case of recovery. See Orphan status for details.

Пример:

box.cfg { replication_connect_quorum = 2 }

Тип: целое число
По умолчанию: null
Environment variable: TT_REPLICATION_CONNECT_QUORUM
Динамический: да
replication_skip_conflict

Since version 1.10.1.

By default, if a replica adds a unique key that another replica has added, replication stops with error = ER_TUPLE_FOUND.

Однако если указать replication_skip_conflict = true, пользователи могут задать пропуск таких ошибок. Так, вместо сохранения сломанной транзакции в xlog, там будет записано NOP (No operation).

Пример:

box.cfg{replication_skip_conflict=true}

Тип: логический
По умолчанию: false (ложь)
Environment variable: TT_REPLICATION_SKIP_CONFLICT
Динамический: да

Примечание

replication_skip_conflict = true рекомендуется использовать только для ручного восстановления репликации.

replication_sync_lag

Since version 1.9.0.

The maximum lag allowed for a replica. When a replica syncs (gets updates from a master), it may not catch up completely. The number of seconds that the replica is behind the master is called the «lag». Syncing is considered to be complete when the replica’s lag is less than or equal to replication_sync_lag.

Если пользователь задает значение replication_sync_lag, равное nil или 365 * 100 * 86400 (TIMEOUT_INFINITY), то отставание не имеет значения – реплика всегда будет синхронизирована. Кроме того, отставание не учитывается (считается бесконечным), если мастер работает на версии Tarantool старше 1.7.7, которая не отправляет сообщения контрольного сигнала.

Этот параметр не учитывается во время настройки. Для получения подробной информации, см. статус orphan.


Тип: число с плавающей запятой
По умолчанию: 10
Environment variable: TT_REPLICATION_SYNC_LAG
Динамический: да
replication_sync_timeout

Since version 1.10.2.

The number of seconds that a node waits when trying to sync with other nodes in a replica set (see bootstrap_strategy), after connecting or during configuration update. This could fail indefinitely if replication_sync_lag is smaller than network latency, or if the replica cannot keep pace with master updates. If replication_sync_timeout expires, the replica enters orphan status.


Тип: число с плавающей запятой
По умолчанию: 300
Environment variable: TT_REPLICATION_SYNC_TIMEOUT
Динамический: да

Примечание

The default replication_sync_timeout value is going to be changed in future versions from 300 to 0. You can learn the reasoning behind this decision from the Default value for replication_sync_timeout topic, which also describes how to try the new behavior in the current version.

replication_timeout

Since version 1.7.5.

If the master has no updates to send to the replicas, it sends heartbeat messages every replication_timeout seconds, and each replica sends an ACK packet back.

И мастер, и реплики запрограммированы разорвать соединение при отсутствии сообщений в течение четырех промежутков времени, указанного в параметре replication_timeout. После разрыва соединения реплика пытается снова подключиться к мастеру.

См. дополнительную информацию в разделе Мониторинг набора реплик.


Тип: целое число
По умолчанию: 1
Environment variable: TT_REPLICATION_TIMEOUT
Динамический: да
replicaset_uuid

Since version 1.9.0.

As described in section «Replication architecture», each replica set is identified by a universally unique identifier called replica set UUID, and each instance is identified by an instance UUID.

Как правило, достаточно позволить системе сгенерировать и форматировать строки, содержащие UUID, которые будут храниться постоянно.

Однако, некоторые администраторы предпочитают сохранять конфигурацию Tarantool в центральном репозитории, например, Apache ZooKeeper. Они могут самостоятельно присвоить значения экземплярам (instance_uuid) и набору реплик (replicaset_uuid) при первом запуске.

Общие правила:

  • Значения должны быть действительно уникальными; они не должны одновременно принадлежать другим экземплярам или наборам реплик в той же инфраструктуре.
  • Значения должны использоваться постоянно, неизменно с первого запуска (первоначальные значения хранятся в файлах снимков и проверяются при каждом перезапуске системы).
  • Значения должны соответствовать требованиям RFC 4122. Нулевой UUID не допускается.

Формат UUID включает в себя шестнадцать октетов, представленных в виде 32 шестнадцатеричных чисел (с основанием 16) в пяти группах, разделенных дефисами в форме 8-4-4-4-12 – 36 символов (32 буквенно-цифровых символа и четыре дефиса).

Пример:

box.cfg{replicaset_uuid='7b853d13-508b-4b8e-82e6-806f088ea6e9'}

Тип: строка
По умолчанию: null
Environment variable: TT_REPLICASET_UUID
Динамический: нет
instance_uuid

Since version 1.9.0.

For replication administration purposes, it is possible to set the universally unique identifiers of the instance (instance_uuid) and the replica set (replicaset_uuid), instead of having the system generate the values.

Для получения подробной информации см. описание параметра replicaset_uuid.

Пример:

box.cfg{instance_uuid='037fec43-18a9-4e12-a684-a42b716fcd02'}

Тип: строка
По умолчанию: null
Environment variable: TT_INSTANCE_UUID
Динамический: нет
replication_synchro_quorum

Since version 2.5.1.

For synchronous replication only. This option tells how many replicas should confirm the receipt of a synchronous transaction before it can finish its commit.

Since version 2.5.3, the option supports dynamic evaluation of the quorum number. That is, the number of quorum can be specified not as a constant number, but as a function instead. In this case, the option returns the formula evaluated. The result is treated as an integer number. Once any replicas are added or removed, the expression is re-evaluated automatically.

For example,

box.cfg{replication_synchro_quorum = "N / 2 + 1"}

Where N is a current number of registered replicas in a cluster.

Keep in mind that the example above represents a canonical quorum definition. The formula at least 50% of the cluster size + 1 guarantees data reliability. Using a value less than the canonical one might lead to unexpected results, including a split-brain.

Since version 2.10.0, this option does not account for anonymous replicas.

По умолчанию значение параметра равно N / 2 + 1.

Она не используется на репликах, поэтому если мастер умирает, отложенные синхронные транзакции будут ждать на репликах до тех пор, пока не будет выбран новый мастер.

Если значение параметра равно 1, синхронные транзакции работают как асинхронные, пока они не настроены. 1 означает, что для коммита достаточно успешной записи в WAL на мастере.


Тип: число
Default: N / 2 + 1 (before version 2.10.0, the default value was 1)
Environment variable: TT_REPLICATION_SYNCHRO_QUORUM
Динамический: да
replication_synchro_timeout

Since version 2.5.1.

For synchronous replication only. Tells how many seconds to wait for a synchronous transaction quorum replication until it is declared failed and is rolled back.

Она не используется на репликах, поэтому если мастер умирает, отложенные синхронные транзакции будут ждать на репликах до тех пор, пока не будет выбран новый мастер.


Тип: число
По умолчанию: 5
Environment variable: TT_REPLICATION_SYNCHRO_TIMEOUT
Динамический: да
replication_threads

Since version 2.10.0.

The number of threads spawned to decode the incoming replication data.

The default value is 1. It means that a single separate thread handles all the incoming replication streams. In most cases, one thread is enough for all incoming data. Therefore, it is likely that the user will not need to set this configuration option.

Possible values range from 1 to 1000. If there are multiple replication threads, connections to serve are distributed evenly between the threads.


Тип: число
По умолчанию: 1
Possible values: from 1 to 1000
Environment variable: TT_REPLICATION_THREADS
Dynamic: no
election_mode

Since version 2.6.1.

Specify the role of a replica set node in the leader election process.

Possible values:

  • off
  • voter
  • candidate
  • manual.

Participation of a replica set node in the automated leader election can be turned on and off by this option.

The default value is off. All nodes that have values other than off run the Raft state machine internally talking to other nodes according to the Raft leader election protocol. When the option is off, the node accepts Raft messages from other nodes, but it doesn’t participate in the election activities, and this doesn’t affect the node’s state. So, for example, if a node is not a leader but it has election_mode = 'off', it is writable anyway.

You can control which nodes can become a leader. If you want a node to participate in the election process but don’t want that it becomes a leaders, set the election_mode option to voter. In this case, the election works as usual, this particular node will vote for other nodes, but won’t become a leader.

If the node should be able to become a leader, use election_mode = 'candidate'.

Since version 2.8.2, the manual election mode is introduced. It may be used when a user wants to control which instance is the leader explicitly instead of relying on the Raft election algorithm.

When an instance is configured with the election_mode='manual', it behaves as follows:

  • By default, the instance acts like a voter – it is read-only and may vote for other instances that are candidates.
  • Once box.ctl.promote() is called, the instance becomes a candidate and starts a new election round. If the instance wins the elections, it becomes a leader, but won’t participate in any new elections.

Тип: строка
Default: „off“
Environment variable: TT_ELECTION_MODE
Динамический: да
election_timeout

Since version 2.6.1.

Specify the timeout between election rounds in the leader election process if the previous round ended up with a split-vote.

In the leader election process, there can be an election timeout for the case of a split-vote. The timeout can be configured using this option; the default value is 5 seconds.

It is quite big, and for most of the cases it can be freely lowered to 300-400 ms. It can be a floating point value (300 ms would be box.cfg{election_timeout = 0.3}).

To avoid the split vote repeat, the timeout is randomized on each node during every new election, from 100% to 110% of the original timeout value. For example, if the timeout is 300 ms and there are 3 nodes started the election simultaneously in the same term, they can set their election timeouts to 300, 310, and 320 respectively, or to 305, 302, and 324, and so on. In that way, the votes will never be split because the election on different nodes won’t be restarted simultaneously.


Тип: число
По умолчанию: 5
Environment variable: TT_ELECTION_TIMEOUT
Динамический: да
election_fencing_mode

Since version 2.11.0.

In earlier Tarantool versions, use election_fencing_enabled instead.

Specify the leader fencing mode that affects the leader election process. When the parameter is set to soft or strict, the leader resigns its leadership if it has less than replication_synchro_quorum of alive connections to the cluster nodes. The resigning leader receives the status of a follower in the current election term and becomes read-only.

  • In soft mode, a connection is considered dead if there are no responses for 4*replication_timeout seconds both on the current leader and the followers.
  • In strict mode, a connection is considered dead if there are no responses for 2*replication_timeout seconds on the current leader and 4*replication_timeout seconds on the followers. This improves chances that there is only one leader at any time.

Fencing applies to the instances that have the election_mode set to candidate or manual. To turn off leader fencing, set election_fencing_mode to off.


Тип: строка
Default: „soft“
Environment variable: TT_ELECTION_FENCING_MODE
Динамический: да
instance_name

Since version 3.0.0.

Specify the instance name. This value must be unique in a replica set.

The following rules are applied to instance names:

  • The maximum number of symbols is 63.
  • Should start with a letter.
  • Can contain lowercase letters (a-z). If uppercase letters are used, they are converted to lowercase.
  • Can contain digits (0-9).
  • Can contain the following characters: -, _.

To change or remove the specified name, you should temporarily set the box.cfg.force_recovery configuration option to true. When all the names are updated and all the instances synced, box.cfg.force_recovery can be set back to false.

Примечание

The instance name is persisted in the box.space._cluster system space.

See also: box.info.name


Тип: строка
По умолчанию: null
Environment variable: TT_INSTANCE_NAME
Динамический: нет
replicaset_name

Since version 3.0.0.

Specify the name of a replica set to which this instance belongs. This value must be the same for all instances of the replica set.

See the instance_name description to learn:

  • which rules are applied to names
  • how to change or remove an already specified name

Примечание

The replica set name is persisted in the box.space._schema system space.

See also: box.info.replicaset


Тип: строка
По умолчанию: null
Environment variable: TT_REPLICASET_NAME
Динамический: нет
cluster_name

Since version 3.0.0.

Specify the name of a cluster to which this instance belongs. This value must be the same for all instances of the cluster.

See the instance_name description to learn:

  • which rules are applied to names
  • how to change or remove an already specified name

Примечание

The cluster name is persisted in the box.space._schema system space.

See also: box.info.cluster


Тип: строка
По умолчанию: null
Environment variable: TT_CLUSTER_NAME
Динамический: нет

Работа с сетями

io_collect_interval

Since version 1.4.9.

The instance will sleep for io_collect_interval seconds between iterations of the event loop. Can be used to reduce CPU load in deployments in which the number of client connections is large, but requests are not so frequent (for example, each connection issues just a handful of requests per second).


Тип: число с плавающей запятой
По умолчанию: null
Environment variable: TT_IO_COLLECT_INTERVAL
Динамический: да
net_msg_max

Since version 1.10.1.

To handle messages, Tarantool allocates fibers. To prevent fiber overhead from affecting the whole system, Tarantool restricts how many messages the fibers handle, so that some pending requests are blocked.

В мощных системах увеличьте значение net_msg_max, и планировщик немедленно приступит к обработке отложенных запросов.

В более слабых системах уменьшите значение net_msg_max, чтобы снизить загрузку, хотя это и займет некоторое время, поскольку планировщик будет ожидать завершения уже запущенных запросов.

When net_msg_max is reached, Tarantool suspends processing of incoming packages until it has processed earlier messages. This is not a direct restriction of the number of fibers that handle network messages, rather it is a system-wide restriction of channel bandwidth. This in turn causes restriction of the number of incoming network messages that the transaction processor thread handles, and therefore indirectly affects the fibers that handle network messages. (The number of fibers is smaller than the number of messages because messages can be released as soon as they are delivered, while incoming requests might not be processed until some time after delivery.)

Для стандартных систем подойдет значение, используемое по умолчанию (768).


Тип: целое число
По умолчанию: 768
Environment variable: TT_NET_MSG_MAX
Динамический: да
readahead

Since version 1.6.2.

The size of the read-ahead buffer associated with a client connection. The larger the buffer, the more memory an active connection consumes and the more requests can be read from the operating system buffer in a single system call. The rule of thumb is to make sure the buffer can contain at least a few dozen requests. Therefore, if a typical tuple in a request is large, e.g. a few kilobytes or even megabytes, the read-ahead buffer size should be increased. If batched request processing is not used, it’s prudent to leave this setting at its default.


Тип: целое число
По умолчанию: 16320
Environment variable: TT_READAHEAD
Динамический: да
iproto_threads

Since version 2.8.1.

The number of network threads. There can be unusual workloads where the network thread is 100% loaded and the transaction processor thread is not, so the network thread is a bottleneck. In that case set iproto_threads to 2 or more. The operating system kernel will determine which connection goes to which thread.

On typical systems, the default value (1) is correct.


Тип: целое число
По умолчанию: 1
Environment variable: TT_IPROTO_THREADS
Динамический: нет

Запись в журнал

This section provides information on how to configure options related to logging. You can also use the log module to configure logging in your application.

log_level

Since version 1.6.2.

Specify the level of detail the log has. There are the following levels:

  • 0 – fatal
  • 1 – syserror
  • 2 – error
  • 3 – crit
  • 4 – warn
  • 5 – info
  • 6 – verbose
  • 7 – debug

By setting log_level, you can enable logging of all events with severities above or equal to the given level. Tarantool prints logs to the standard error stream by default. This can be changed with the log configuration parameter.


Type: integer, string
По умолчанию: 5
Environment variable: TT_LOG_LEVEL
Динамический: да

Примечание

Prior to Tarantool 1.7.5 there were only six levels and DEBUG was level 6. Starting with Tarantool 1.7.5, VERBOSE is level 6 and DEBUG is level 7. VERBOSE is a new level for monitoring repetitive events which would cause too much log writing if INFO were used instead.

log

Since version 1.7.4.

By default, Tarantool sends the log to the standard error stream (stderr). If log is specified, Tarantool can send the log to a:

  • file
  • pipe
  • system logger

Example 1: sending the log to the tarantool.log file.

box.cfg{log = 'tarantool.log'}
-- или
box.cfg{log = 'file:tarantool.log'}

This opens the file tarantool.log for output on the server’s default directory. If the log string has no prefix or has the prefix «file:», then the string is interpreted as a file path.

Example 2: sending the log to a pipe.

box.cfg{log = '| cronolog tarantool.log'}
-- or
box.cfg{log = 'pipe: cronolog tarantool.log'}

This starts the program cronolog when the server starts, and sends all log messages to the standard input (stdin) of cronolog. If the log string begins with „|“ or has the prefix «pipe:», then the string is interpreted as a Unix pipeline.

Example 3: sending the log to syslog.

box.cfg{log = 'syslog:identity=tarantool'}
-- или
box.cfg{log = 'syslog:facility=user'}
-- или
box.cfg{log = 'syslog:identity=tarantool,facility=user'}
-- или
box.cfg{log = 'syslog:server=unix:/dev/log'}

If the log string begins with «syslog:», then it is interpreted as a message for the syslogd program, which normally is running in the background on any Unix-like platform. The setting can be syslog:, syslog:facility=..., syslog:identity=..., syslog:server=..., or a combination.

  • The syslog:identity setting is an arbitrary string, which is placed at the beginning of all messages. The default value is «tarantool».
  • В настоящий момент настройка syslog:facility не учитывается, но будет использоваться в дальнейшем. Ее значением должно быть одно из ключевых слов syslog, которые сообщают программе syslogd, куда отправлять сообщение. Возможные значения: auth, authpriv, cron, daemon, ftp, kern, lpr, mail, news, security, syslog, user, uucp, local0, local1, local2, local3, local4, local5, local6, local7. По умолчанию: user.
  • The syslog:server setting is the locator for the syslog server. It can be a Unix socket path beginning with «unix:», or an ipv4 port number. The default socket value is: dev/log (on Linux) or /var/run/syslog (on macOS). The default port value is: 514, the UDP port.

When logging to a file, Tarantool reopens the log on SIGHUP. When log is a program, its PID is saved in the log.pid variable. You need to send it a signal to rotate logs.


Тип: строка
По умолчанию: null
Environment variable: TT_LOG
Динамический: нет
log_nonblock

Since version 1.7.4.

If log_nonblock equals true, Tarantool does not block during logging when the system is not ready for writing, and drops the message instead. If log_level is high, and many messages go to the log, setting log_nonblock to true may improve logging performance at the cost of some log messages getting lost.

This parameter has effect only if log is configured to send logs to a pipe or system logger. The default log_nonblock value is nil, which means that blocking behavior corresponds to the logger type:

  • false for stderr and file loggers.
  • true for a pipe and system logger.

This is a behavior change: in earlier versions of the Tarantool server, the default value was true.


Тип: логический
По умолчанию: nil
Environment variable: TT_LOG_NONBLOCK
Динамический: нет
too_long_threshold

Since version 1.6.2.

If processing a request takes longer than the given value (in seconds), warn about it in the log. Has effect only if log_level is greater than or equal to 4 (WARNING).


Тип: число с плавающей запятой
По умолчанию: 0.5
Environment variable: TT_TOO_LONG_THRESHOLD
Динамический: да
log_format

Since version 1.7.6.

Log entries have two possible formats:

  • „plain“ (по умолчанию) или
  • „json“ (более детально с JSON-метками).

Here is what a log entry looks like if box.cfg{log_format='plain'}:

2017-10-16 11:36:01.508 [18081] main/101/interactive I> set 'log_format' configuration option to "plain"

Here is what a log entry looks like if box.cfg{log_format='json'}:

{"time": "2017-10-16T11:36:17.996-0600",
"level": "INFO",
"message": "set 'log_format' configuration option to \"json\"",
"pid": 18081,|
"cord_name": "main",
"fiber_id": 101,
"fiber_name": "interactive",
"file": "builtin\/box\/load_cfg.lua",
"line": 317}

The log_format='plain' entry has a time value, process ID, cord name, fiber_id, fiber_name, log level, and message.

The log_format='json' entry has the same fields along with their labels, and in addition has the file name and line number of the Tarantool source.


Тип: строка
По умолчанию: „plain“
Environment variable: TT_LOG_FORMAT
Динамический: да
log_modules

Since version 2.11.0.

Configure the specified log levels (log_level) for different modules.

You can specify a logging level for the following module types:


Type: table
Default: blank
Environment variable: TT_LOG_MODULES
Динамический: да

Example 1: Set log levels for files that use the default logger

Suppose you have two identical modules placed by the following paths: test/logging/module1.lua and test/logging/module2.lua. These modules use the default logger and look as follows:

return {
    say_hello = function()
        local log = require('log')
        log.info('Info message from module1')
    end
}

To load these modules in your application, you need to add the corresponding require directives:

module1 = require('test.logging.module1')
module2 = require('test.logging.module2')

To configure logging levels, you need to provide module names corresponding to paths to these modules. In the example below, the box_cfg variable contains logging settings that can be passed to the box.cfg() function:

box_cfg = { log_modules = {
    ['test.logging.module1'] = 'verbose',
    ['test.logging.module2'] = 'error' }
}

Given that module1 has the verbose logging level and module2 has the error level, calling module1.say_hello() shows a message but module2.say_hello() is swallowed:

-- Prints 'info' messages --
module1.say_hello()
--[[
[92617] main/103/interactive/test.logging.module1 I> Info message from module1
---
...
--]]

-- Swallows 'info' messages --
module2.say_hello()
--[[
---
...
--]]

Example 2: Set log levels for modules that use custom loggers

In the example below, the box_cfg variable contains logging settings that can be passed to the box.cfg() function. This example shows how to set the verbose level for module1 and the error level for module2:

box_cfg = { log_level = 'warn',
            log_modules = {
                module1 = 'verbose',
                module2 = 'error' }
}

To create custom loggers, call the log.new() function:

-- Creates new loggers --
module1_log = require('log').new('module1')
module2_log = require('log').new('module2')

Given that module1 has the verbose logging level and module2 has the error level, calling module1_log.info() shows a message but module2_log.info() is swallowed:

-- Prints 'info' messages --
module1_log.info('Info message from module1')
--[[
[16300] main/103/interactive/module1 I> Info message from module1
---
...
--]]

-- Swallows 'debug' messages --
module1_log.debug('Debug message from module1')
--[[
---
...
--]]

-- Swallows 'info' messages --
module2_log.info('Info message from module2')
--[[
---
...
--]]

Example 3: Set a log level for C modules

In the example below, the box_cfg variable contains logging settings that can be passed to the box.cfg() function. This example shows how to set the info level for the tarantool module:

box_cfg = { log_level = 'warn',
            log_modules = { tarantool = 'info' } }

The specified level affects messages logged from C modules:

ffi = require('ffi')

-- Prints 'info' messages --
ffi.C._say(ffi.C.S_INFO, nil, 0, nil, 'Info message from C module')
--[[
[6024] main/103/interactive I> Info message from C module
---
...
--]]

-- Swallows 'debug' messages --
ffi.C._say(ffi.C.S_DEBUG, nil, 0, nil, 'Debug message from C module')
--[[
---
...
--]]

The example above uses the LuaJIT ffi library to call C functions provided by the say module.

Пример записи в журнал

This example illustrates how «rotation» works, that is, what happens when the server instance is writing to a log and signals are used when archiving it.

  1. Start with two terminal shells: Terminal #1 and Terminal #2.

  2. In Terminal #1, start an interactive Tarantool session. Then, use the log property to send logs to Log_file and call log.info to put a message in the log file.

    box.cfg{log='Log_file'}
log = require('log')
log.info('Log Line #1')

  3. In Terminal #2, use the mv command to rename the log file to Log_file.bak.

    mv Log_file Log_file.bak

    As a result, the next log message will go to Log_file.bak.

  4. Go back to Terminal #1 and put a message «Log Line #2» in the log file.

    log.info('Log Line #2')

  5. In Terminal #2, use ps to find the process ID of the Tarantool instance.

    ps -A | grep tarantool

  6. In Terminal #2, execute kill -HUP to send a SIGHUP signal to the Tarantool instance. Tarantool will open Log_file again, and the next log message will go to Log_file.

    kill -HUP process_id

    The same effect could be accomplished by calling log.rotate.

  7. In Terminal #1, put a message «Log Line #3» in the log file.

    log.info('Log Line #3')

  8. In Terminal #2, use less to examine files. Log_file.bak will have the following lines …

    2015-11-30 15:13:06.373 [27469] main/101/interactive I> Log Line #1`
2015-11-30 15:14:25.973 [27469] main/101/interactive I> Log Line #2`

    … and Log_file will look like this:

    log file has been reopened
2015-11-30 15:15:32.629 [27469] main/101/interactive I> Log Line #3

Audit log

Enterprise Edition

Audit log features are available in the Enterprise Edition only.

The audit_* parameters define configuration related to audit logging.

audit_extract_key

Since: 3.0.0.

If set to true, the audit subsystem extracts and prints only the primary key instead of full tuples in DML events (space_insert, space_replace, space_delete). Otherwise, full tuples are logged. The option may be useful in case tuples are big.


Тип: логический
По умолчанию: false (ложь)
Environment variable: TT_AUDIT_EXTRACT_KEY
audit_filter

Enable logging for a specified subset of audit events. This option accepts the following values:

  • Event names (for example, password_change). For details, see Audit log events.
  • Event groups (for example, audit). For details, see Event groups.

The option contains either one value from Possible values section (see below) or a combination of them.

To enable custom audit log events, specify the custom value in this option.

The default value is compatibility, which enables logging of all events available before 2.10.0.

Example

box.cfg{
    audit_log = 'audit.log',
    audit_filter = 'audit,auth,priv,password_change,access_denied'
   }

Type: array
Possible values: „all“, „audit“, „auth“, „priv“, „ddl“, „dml“, „data_operations“, „compatibility“, „audit_enable“, „auth_ok“, „auth_fail“, „disconnect“, „user_create“, „user_drop“, „role_create“, „role_drop“, „user_disable“, „user_enable“, „user_grant_rights“, „role_grant_rights“, „role_revoke_rights“, „password_change“, „access_denied“, „eval“, „call“, „space_select“, „space_create“, „space_alter“, „space_drop“, „space_insert“, „space_replace“, „space_delete“, „custom“
Default: „compatibility“
Environment variable: TT_AUDIT_FILTER
audit_format

Specify the format that is used for the audit log events – plain text, CSV or JSON format.

Plain text is used by default. This human-readable format can be efficiently compressed.

box.cfg{audit_log = 'audit.log', audit_format = 'plain'}

Example

remote: session_type:background module:common.admin.auth user: type:custom_tdg_audit tag:tdg_severity_INFO description:[5e35b406-4274-4903-857b-c80115275940] subj: "anonymous", msg: "Access granted to anonymous user"

The JSON format is more convenient to receive log events, analyze them and integrate them with other systems if needed.

box.cfg{audit_log = 'audit.log', audit_format = 'json'}

Example

{"time": "2022-11-17T21:55:49.880+0300", "remote": "", "session_type": "background", "module": "common.admin.auth", "user": "", "type": "custom_tdg_audit", "tag": "tdg_severity_INFO", "description": "[c26cd11a-3342-4ce6-8f0b-a4b222268b9d] subj: \"anonymous\", msg: \"Access granted to anonymous user\""}

Using the CSV format allows you to view audit log events in tabular form.

box.cfg{audit_log = 'audit.log', audit_format = 'csv'}

Example

2022-11-17T21:58:03.131+0300,,background,common.admin.auth,,,custom_tdg_audit,tdg_severity_INFO,"[b3dfe2a3-ec29-4e61-b747-eb2332c83b2e] subj: ""anonymous"", msg: ""Access granted to anonymous user"""

Тип: строка
Possible values: „json“, „csv“, „plain“
Default: „json“
Environment variable: TT_AUDIT_FORMAT
audit_log

Enable audit logging and define the log location.

This option accepts a string value that allows you to define the log location. The following locations are supported:

  • File: to write audit logs to a file, specify a path to a file (with an optional file prefix)
  • Pipeline: to start a program and write audit logs to it, specify a program name (with | or pipe prefix)
  • System log: to write audit logs to a system log, specify a message for syslogd (with syslog prefix)

See the examples below.

By default, audit logging is disabled.

Example: Writing to a file

box.cfg{audit_log = 'audit_tarantool.log'}
-- or
box.cfg{audit_log = 'file:audit_tarantool.log'}

This opens the audit_tarantool.log file for output in the server’s default directory. If the audit_log string has no prefix or the prefix file:, the string is interpreted as a file path.

If you log to a file, Tarantool will reopen the audit log at SIGHUP.

Example: Sending to a pipeline

box.cfg{audit_log = '| cronolog audit_tarantool.log'}
-- or
box.cfg{audit_log = 'pipe: cronolog audit_tarantool.log'}'

This starts the cronolog program when the server starts and sends all audit_log messages to cronolog’s standard input (stdin). If the audit_log string starts with „|“ or contains the prefix pipe:, the string is interpreted as a Unix pipeline.

If log is a program, check out its pid and send it a signal to rotate logs.

Example: Writing to a system log

Предупреждение

Below is an example of writing audit logs to a directory shared with the system logs. Tarantool allows this option, but it is not recommended to do this to avoid difficulties when working with audit logs. System and audit logs should be written separately. To do this, create separate paths and specify them.

This sample configuration sends the audit log to syslog:

box.cfg{audit_log = 'syslog:identity=tarantool'}
-- or
box.cfg{audit_log = 'syslog:facility=user'}
-- or
box.cfg{audit_log = 'syslog:identity=tarantool,facility=user'}
-- or
box.cfg{audit_log = 'syslog:server=unix:/dev/log'}

If the audit_log string starts with «syslog:», it is interpreted as a message for the syslogd program, which normally runs in the background of any Unix-like platform. The setting can be „syslog:“, „syslog:facility=…“, „syslog:identity=…“, „syslog:server=…“ or a combination.

The syslog:identity setting is an arbitrary string that is placed at the beginning of all messages. The default value is tarantool.

The syslog:facility setting is currently ignored, but will be used in the future. The value must be one of the syslog keywords that tell syslogd where to send the message. The possible values are auth, authpriv, cron, daemon, ftp, kern, lpr, mail, news, security, syslog, user, uucp, local0, local1, local2, local3, local4, local5, local6, local7. The default value is local7.

The syslog:server setting is the locator for the syslog server. It can be a Unix socket path starting with «unix:» or an ipv4 port number. The default socket value is /dev/log (on Linux) or /var/run/syslog (on Mac OS). The default port value is 514, which is the UDP port.

An example of a Tarantool audit log entry in the syslog:

09:32:52 tarantool_audit: {"time": "2024-02-08T09:32:52.190+0300", "uuid": "94454e46-9a0e-493a-bb9f-d59e44a43581", "severity": "INFO", "remote": "unix/:(socket)", "session_type": "console", "module": "tarantool", "user": "admin", "type": "space_create", "tag": "", "description": "Create space bands"}

Тип: строка
Possible values: see the string format above
Default: „nill“
Environment variable: TT_AUDIT_LOG
audit_nonblock

Specify the logging behavior if the system is not ready to write. If set to true, Tarantool does not block during logging if the system is non-writable and writes a message instead. Using this value may improve logging performance at the cost of losing some log messages.

Примечание

The option only has an effect if the audit_log is set to syslog or pipe.

Setting audit_nonblock to true is not allowed if the output is to a file. In this case, set audit_nonblock to false.


Тип: логический
По умолчанию: true
Environment variable: TT_AUDIT_NONBLOCK
audit_spaces

Since: 3.0.0.

The array of space names for which data operation events (space_select, space_insert, space_replace, space_delete) should be logged. The array accepts string values. If set to box.NULL, the data operation events are logged for all spaces.

Example

In the example, only the events of bands and singers spaces are logged:

box.cfg{
    audit_spaces = 'bands,singers'
   }

Type: array
Default: box.NULL
Environment variable: TT_AUDIT_SPACES

Authentication

Enterprise Edition

Authentication features are supported by the Enterprise Edition only.

auth_delay

Since 2.11.0.

Specify a period of time (in seconds) that a specific user should wait for the next attempt after failed authentication.

With the configuration below, Tarantool refuses the authentication attempt if the previous attempt was less than 5 seconds ago.

box.cfg{ auth_delay = 5 }

Тип: число
Default: 0
Environment variable: TT_AUTH_DELAY
Динамический: да
auth_retries

Since 3.0.0.

Specify the maximum number of authentication retries allowed before auth_delay is enforced. The default value is 0, which means auth_delay is enforced after the first failed authentication attempt.

The retry counter is reset after auth_delay seconds since the first failed attempt. For example, if a client tries to authenticate fewer than auth_retries times within auth_delay seconds, no authentication delay is enforced. The retry counter is also reset after any successful authentication attempt.


Тип: число
Default: 0
Environment variable: TT_AUTH_RETRIES
Динамический: да
auth_type

Since 2.11.0.

Specify an authentication protocol:

  • „chap-sha1“: use the CHAP protocol to authenticate users with SHA-1 hashing applied to passwords.
  • „pap-sha256“: use PAP authentication with the SHA256 hashing algorithm.

For new users, the box.schema.user.create method will generate authentication data using PAP-SHA256. For existing users, you need to reset a password using box.schema.user.passwd to use the new authentication protocol.


Тип: строка
Default value: „chap-sha1“
Environment variable: TT_AUTH_TYPE
Динамический: да
disable_guest

Since 2.11.0.

If true, disables access over remote connections from unauthenticated or guest access users. This option affects both net.box and replication connections.


Тип: логический
По умолчанию: false (ложь)
Environment variable: TT_DISABLE_GUEST
Динамический: да
password_min_length

Since 2.11.0.

Specify the minimum number of characters for a password.

The following example shows how to set the minimum password length to 10.

box.cfg{ password_min_length = 10 }

Тип: целое число
Default: 0
Environment variable: TT_PASSWORD_MIN_LENGTH
Динамический: да
password_enforce_uppercase

Since 2.11.0.

If true, a password should contain uppercase letters (A-Z).


Тип: логический
По умолчанию: false (ложь)
Environment variable: TT_PASSWORD_ENFORCE_UPPERCASE
Динамический: да
password_enforce_lowercase

Since 2.11.0.

If true, a password should contain lowercase letters (a-z).


Тип: логический
По умолчанию: false (ложь)
Environment variable: TT_PASSWORD_ENFORCE_LOWERCASE
Динамический: да
password_enforce_digits

Since 2.11.0.

If true, a password should contain digits (0-9).


Тип: логический
По умолчанию: false (ложь)
Environment variable: TT_PASSWORD_ENFORCE_DIGITS
Динамический: да
password_enforce_specialchars

Since 2.11.0.

If true, a password should contain at least one special character (such as &|?!@$).


Тип: логический
По умолчанию: false (ложь)
Environment variable: TT_PASSWORD_ENFORCE_SPECIALCHARS
Динамический: да
password_lifetime_days

Since 2.11.0.

Specify the maximum period of time (in days) a user can use the same password. When this period ends, a user gets the «Password expired» error on a login attempt. To restore access for such users, use box.schema.user.passwd.

Примечание

The default 0 value means that a password never expires.

The example below shows how to set a maximum password age to 365 days.

box.cfg{ password_lifetime_days = 365 }

Тип: целое число
Default: 0
Environment variable: TT_PASSWORD_LIFETIME_DAYS
Динамический: да
password_history_length

Since 2.11.0.

Specify the number of unique new user passwords before an old password can be reused.

In the example below, a new password should differ from the last three passwords.

box.cfg{ password_history_length = 3 }

Тип: целое число
Default: 0
Environment variable: TT_PASSWORD_HISTORY_LENGTH
Динамический: да

Примечание

Tarantool uses the auth_history field in the box.space._user system space to store user passwords.

Flight recorder

Enterprise Edition

The flight recorder is available in the Enterprise Edition only.

flightrec_enabled

Since 2.11.0.

Enable the flight recorder.


Тип: логический
По умолчанию: false (ложь)
Environment variable: TT_FLIGHTREC_ENABLED
Динамический: да
flightrec_logs_size

Since 2.11.0.

Specify the size (in bytes) of the log storage. You can set this option to 0 to disable the log storage.


Тип: целое число
Default: 10485760
Environment variable: TT_FLIGHTREC_LOGS_SIZE
Динамический: да
flightrec_logs_max_msg_size

Since 2.11.0.

Specify the maximum size (in bytes) of the log message. The log message is truncated if its size exceeds this limit.


Тип: целое число
Default: 4096
Maximum: 16384
Environment variable: TT_FLIGHTREC_LOGS_MAX_MSG_SIZE
Динамический: да
flightrec_logs_log_level

Since 2.11.0.

Specify the level of detail the log has. You can learn more about log levels from the log_level option description. Note that the flightrec_logs_log_level value might differ from log_level.


Тип: целое число
Default: 6
Environment variable: TT_FLIGHTREC_LOGS_LOG_LEVEL
Динамический: да
flightrec_metrics_period

Since 2.11.0.

Specify the time period (in seconds) that defines how long metrics are stored from the moment of dump. So, this value defines how much historical metrics data is collected up to the moment of crash. The frequency of metric dumps is defined by flightrec_metrics_interval.


Тип: целое число
Default: 180
Environment variable: TT_FLIGHTREC_METRICS_PERIOD
Динамический: да
flightrec_metrics_interval

Since 2.11.0.

Specify the time interval (in seconds) that defines the frequency of dumping metrics. This value shouldn’t exceed flightrec_metrics_period.

Примечание

Given that the average size of a metrics entry is 2 kB, you can estimate the size of the metrics storage as follows:

(flightrec_metrics_period / flightrec_metrics_interval) * 2 kB

Тип: число
По умолчанию: 1.0
Minimum: 0.001
Environment variable: TT_FLIGHTREC_METRICS_INTERVAL
Динамический: да
flightrec_requests_size

Since 2.11.0.

Specify the size (in bytes) of storage for the request and response data. You can set this parameter to 0 to disable a storage of requests and responses.


Тип: целое число
Default: 10485760
Environment variable: TT_FLIGHTREC_REQUESTS_SIZE
Динамический: да
flightrec_requests_max_req_size

Since 2.11.0.

Specify the maximum size (in bytes) of a request entry. A request entry is truncated if this size is exceeded.


Тип: целое число
Default: 16384
Environment variable: TT_FLIGHTREC_REQUESTS_MAX_REQ_SIZE
Динамический: да
flightrec_requests_max_res_size

Since 2.11.0.

Specify the maximum size (in bytes) of a response entry. A response entry is truncated if this size is exceeded.


Тип: целое число
Default: 16384
Environment variable: TT_FLIGHTREC_REQUESTS_MAX_RES_SIZE
Динамический: да

Обратная связь

By default, a Tarantool daemon sends a small packet once per hour, to https://feedback.tarantool.io. The packet contains three values from box.info: box.info.version, box.info.uuid, and box.info.cluster_uuid. By changing the feedback configuration parameters, users can adjust or turn off this feature.

feedback_enabled

Since version 1.10.1.

Whether to send feedback.

Если задано значение true, обратная связь будет отправлена, как описано выше. Если задано значение false, обратная связь не отправляется.


Тип: логический
По умолчанию: true
Environment variable: TT_FEEDBACK_ENABLED
Динамический: да
feedback_host

Since version 1.10.1.

The address to which the packet is sent. Usually the recipient is Tarantool, but it can be any URL.


Тип: строка
Default: https://feedback.tarantool.io
Environment variable: TT_FEEDBACK_HOST
Динамический: да
feedback_interval

Since version 1.10.1.

The number of seconds between sendings, usually 3600 (1 hour).


Тип: число с плавающей запятой
По умолчанию: 3600
Environment variable: TT_FEEDBACK_INTERVAL
Динамический: да

Устаревшие параметры

Данные параметры объявлены устаревшими с версии Tarantool 1.7.4:

logger

Устаревший, заменен параметром log. Параметр был лишь переименован, его тип, значения и семантика остались прежними.

logger_nonblock

Устаревший, заменен параметром log_nonblock. Параметр был лишь переименован, его тип, значения и семантика остались прежними.

panic_on_snap_error

Устаревший, заменен параметром force_recovery.

Если при чтении файла снимка произошла ошибка (при запуске экземпляра сервера), прервать выполнение.


Тип: логический
По умолчанию: true
Динамический: нет
panic_on_wal_error

Устаревший, заменен параметром force_recovery.


Тип: логический
По умолчанию: true
Динамический: да
replication_source

Устаревший, заменен параметром replication. Параметр был лишь переименован, его тип, значения и семантика остались прежними.

slab_alloc_arena

Устаревший, заменен параметром memtx_memory.

Количество памяти, которое Tarantool выделяет для фактического хранения кортежей, в гигабайтах. При достижении предельного значения запросы вставки INSERT или обновления UPDATE выполняться не будут, выдавая ошибку ER_MEMORY_ISSUE. Сервер не выходит за установленный предел памяти memtx_memory при распределении кортежей, но есть дополнительная память, которая используется для хранения индексов и информации о подключении. В зависимости от рабочей конфигурации и загрузки, Tarantool может потреблять на 20% больше установленного предела.


Тип: число с плавающей запятой
По умолчанию: 1.0
Динамический: нет
slab_alloc_maximal

Устаревший, заменен параметром memtx_max_tuple_size. Параметр был лишь переименован, его тип, значения и семантика остались прежними.

slab_alloc_minimal

Устаревший, заменен параметром memtx_min_tuple_size. Параметр был лишь переименован, его тип, значения и семантика остались прежними.

snap_dir

Устаревший, заменен параметром memtx_dir. Параметр был лишь переименован, его тип, значения и семантика остались прежними.

snapshot_period

Устаревший, заменен параметром checkpoint_interval. Параметр был лишь переименован, его тип, значения и семантика остались прежними.

snapshot_count

Устаревший, заменен параметром checkpoint_count. Параметр был лишь переименован, его тип, значения и семантика остались прежними.

rows_per_wal

Deprecated in favor of wal_max_size. The parameter does not allow to properly limit size of WAL logs.

election_fencing_enabled

Deprecated in Tarantool v2.11 in favor of election_fencing_mode.

The parameter does not allow using the strict fencing mode. Setting to true is equivalent to setting the soft election_fencing_mode. Setting to false is equivalent to setting the off election_fencing_mode.


Тип: логический
По умолчанию: true
Environment variable: TT_ELECTION_FENCING_ENABLED
Динамический: да

tarantool command-line options

tarantool is the Tarantool database and application server. This command can be used for different purposes, for example, running a single Tarantool instance or starting an external coordinator used for a supervised failover. The tarantool command also provides additional options that might be helpful for development purposes.

Примечание

The tt utility is the recommended way to start Tarantool instances. Learn more from Starting and stopping instances.

Starting instances using the tarantool command

Below is the syntax for starting a Tarantool instance configured in a file:

$ tarantool [OPTION ...] --name INSTANCE_NAME --config CONFIG_FILE_PATH

The command below starts router-a-001 configured in the config.yaml file:

$ tarantool --name router-a-001 --config config.yaml

Options

-h, --help

Print an annotated list of all available options and exit.

--help-env-list

Since: 3.0.0.

Show a list of environment variables that can be used to configure Tarantool.

--failover

Since: 3.1.0.

Enterprise Edition

This option is supported by the Enterprise Edition only.

Start an external coordinator used for a supervised failover.

--force-recovery

Since: 3.0.0.

Try to start an instance if there is an error while reading a corrupted snapshot or write-ahead log file during the recovery process:

With this option enabled, Tarantool skips invalid records, reads as much data as possible, and lets the process finish with a warning. When the instance has started, call box.snapshot() to make a new snapshot so that the corrupted snapshots or write-ahead logs aren’t used for recovery anymore.

You can also enable force recovery using the TT_FORCE_RECOVERY environment variable. TT_FORCE_RECOVERY has a lower priority than the --force-recovery option.

Example on GitHub: force_recovery

-v, -V, --version

Print the product name and version.

Example

$ tarantool --version
Tarantool Enterprise 3.0.0-beta1-2-gcbb569b4c-r607-gc64
Target: Linux-x86_64-RelWithDebInfo
...

In this example:

  • 3.0.0 is a Tarantool version. Tarantool follows semantic versioning, which is described in the Tarantool release policy section.
  • Target is the platform Tarantool is built on. Platform-specific details may follow this line.
-c, --config PATH

Since: 3.0.0.

Set a path to a YAML configuration file. You can also configure this value using the TT_CONFIG environment variable.

See also: Starting instances using the tarantool command

-n, --name INSTANCE

Since: 3.0.0.

Set the name of an instance to run. You can also configure this value using the TT_INSTANCE_NAME environment variable.

See also: Starting instances using the tarantool command

-i

Enter an interactive mode.

Example

$ tarantool -i
-e EXPR

Execute the „EXPR“ string. See also: lua man page.

Example

$ tarantool -e 'print("Hello, world!")'
Hello, world!
-l NAME

Require the „NAME“ library. See also: lua man page.

Example

$ tarantool -l luatest.coverage script.lua
-j cmd

Perform a LuaJIT control command. See also: Command Line Options.

Example

$ tarantool -j off app.lua
-b ...

Save or list bytecode. See also: Command Line Options.

Example

$ tarantool -b test.lua test.out
-d SCRIPT

Activate a debugging session for „SCRIPT“. See also: luadebug.lua.

Example

$ tarantool -d app.lua
--

Stop handling options. See also: lua man page.

-

Stop handling options and execute the standard input as a file. See also: lua man page.

SQL reference

This reference covers all the SQL statements and clauses supported by Tarantool.

What Tarantool’s SQL product delivers

Tarantool’s SQL is a major new feature that was first introduced with Tarantool version 2.1.
The primary advantages are:
- a high level of SQL compatibility
- an easy way to switch from NoSQL to SQL and back
- the Tarantool brand.

The «high level of SQL compatibility» includes support for joins, subqueries, triggers, indexes, groupings, transactions in a multi-user environment, and conformance with the majority of the mandatory requirements of the SQL:2016 standard.

The «easy way to switch» consists of the fact that the same tables can be operated on with SQL and with the long-established Tarantool-NoSQL product, meaning that when you want standard Relational-DBMS jobs you can do them, and when you want NoSQL capability you can have it (Tarantool-NoSQL outperforms other NoSQL products in public benchmarks).

The «Tarantool brand» comes from the support of a multi-billion-dollar internet / mail / social-network provider, a dozens-of-professionals staff of programmers and support people, a community who believes in open-source BSD licensing, and hundreds of corporations / government bodies using Tarantool products in production already.

The status of Tarantool’s SQL feature is «release». So, it is working now and you can verify that by downloading it and trying all the features, which will be explained in the rest of this document. There is also a tutorial.

Differences from other products

Differences from other SQL products: The Tarantool design requirement is that Tarantool’s SQL conforms to the majority of the listed mandatory requirements of the core SQL:2016 standard, and this will be shown in the specific conformance statements in the feature list in a section about «compliance with the official SQL standard». Possibly the deviations which most people will find notable are: type checking is less strict, and some data definition options must be done with NoSQL syntax.

Differences from other NoSQL products: By examining attempts by others to paste relatively smaller subsets of SQL onto NoSQL products, it should be possible to conclude that Tarantool’s SQL has demonstrably more features and capabilities. The reason is that the Tarantool developers started with a complete code base of a working SQL DBMS and made it work with Tarantool-NoSQL underneath, rather than starting with a NoSQL DBMS and adding syntax to it.

What Tarantool’s SQL manual delivers

The following parts of this document are:
The SQL User Guide explains «How to get Started» and explains the terms and the syntax elements that apply for all SQL statements.
The SQL Statements and Clauses guide explains, for each SQL statement, the format and the rules and the exceptions and the examples and the limitations.
The SQL Plus Lua guide has the details about calling Lua from SQL, calling SQL from Lua, and using the same database objects in both SQL and Lua.
The SQL Features list shows how the product conforms with the mandatory features of the SQL standard.

Users are expected to know what databases are, and experience with other SQL DBMSs would be an advantage. To learn about the basics of relational database management and SQL in particular, check the SQL Beginners“ Guide in the How-to guides section.

SQL user guide

The User Guide describes how users can start up with SQL with Tarantool, and necessary concepts.

Heading Введение
Getting Started Typing SQL statements on a console
Supported Syntax For example what characters are allowed
Concepts tokens, literals, identifiers, operands, operators, expressions, statements
Data type conversion Casting, implicit or explicit

Getting Started

Пояснения по установке и запуску сервера Tarantool приведены в других главах руководства по Tarantool.

To get started specifically with the SQL features, using Tarantool as a client, execute these requests:

box.cfg{}
box.execute([[VALUES ('hello');]])

The bottom of the screen should now look like this:

tarantool> box.execute([[VALUES ('hello');]])
---
- metadata:
  - name: COLUMN_1
    type: string
  rows:
  - ['hello']
...

That’s an SQL statement done with Tarantool.

Now you are ready to execute any SQL statements via the connection. For example

box.execute([[CREATE TABLE things (id INTEGER PRIMARY key,
                                   remark STRING);]])
box.execute([[INSERT INTO things VALUES (55, 'Hello SQL world!');]])
box.execute([[SELECT * FROM things WHERE id > 0;]])

And you will see the results of the SQL query.

For the rest of this chapter, the box.execute([[…]]) enclosure will not be shown. Examples will simply say what a piece of syntax looks like, such as SELECT 'hello';
and users should know that must be entered as
box.execute([[SELECT 'hello';]])
It is also legal to enclose SQL statements inside single or double quote marks instead of [[ … ]].

Supported Syntax

Keywords, for example CREATE or INSERT or VALUES, may be entered in either upper case or lower case.

Literal values, for example 55 or 'Hello SQL world!', should be entered without single quote marks if they are numeric, and should be entered with single quote marks if they are strings.

Object names, for example table1 or column1, should usually be entered without double quote marks and are subject to some restrictions. They may be enclosed in double quote marks and in that case they are subject to fewer restrictions.

Almost all keywords are reserved, which means that they cannot be used as object names unless they are enclosed in double quote marks.

Comments may be between /* and */ (bracketed) or between -- and the end of a line (simple).

INSERT /* This is a bracketed comment */ INTO t VALUES (5);
INSERT INTO t VALUES (5); -- this is a simple comment

Выражения, например a + b или a > b AND NOT a <= b, могут содержать арифметические операторы + - / * и операторы сравнения = > < <= >= LIKE, а также могут использоваться вместе с AND OR NOT, при этом круглые скобки необязательны.

Concepts

In the SQL beginners“ guide there was discussion of:
What are: relational databases, tables, views, rows, and columns?
What are: transactions, write-ahead logs, commits and rollbacks?
What are: security considerations?
How to: add, delete, or update rows in tables?
How to: work inside transactions with commits and/or rollbacks?
How to: select, join, filter, group, and sort rows?

Tarantool has a «schema». A schema is a container for all database objects. A schema may be called a «database» in other DBMS implementations

Tarantool allows four types of «database objects» to be created within the schema: tables, triggers, indexes, and constraints. Within tables, there are «columns».

Almost all Tarantool SQL statements begin with a reserved-word «verb» such as INSERT, and end optionally with a semicolon. For example: INSERT INTO t VALUES (1);

A Tarantool SQL database and a Tarantool NoSQL database are the same thing. However, some operations are only possible with SQL, and others are only possible with NoSQL. Mixing SQL statements with NoSQL requests is allowed.

Tokens

The token is the minimum SQL-syntax unit that Tarantool understands. These are the types of tokens:

Ключевые слова — официальные слова языка, например SELECT.
Литералы — числовые или строковые константы, например 15.7 или 'Taranto'.
Идентификаторы — имена объектов, например column55 или table_of_accounts.
Операторы (строго говоря, неалфавитные операторы) — математические операторы, например * / + - ( ) , ; < = >=.

Токены могут быть отделены друг от друга одним или несколькими разделителями.
* Символы-разделители: табуляция (U+0009), перевод строки (U+000A), вертикальная табуляция (U+000B), смена страницы (U+000C), возврат каретки (U+000D), пробел (U+0020), следующая строка (U+0085), а также все редкие символы классов Zl, Zp и Zs Юникода. Полный список символов вы найдете на странице https://github.com/tarantool/tarantool/issues/2371.
* Комментарии (начинаются с /* и заканчиваются */).
* Однострочные комментарии (начинаются с -- и заканчиваются переводом строки).
Разделители не нужны ни перед операторами, ни после них.
Разделители необходимы после ключевых слов, числовых значений или обычных идентификаторов, если только следующий токен не является оператором.
Таким образом, Tarantool может понять следующую серию из шести токенов:
SELECT'a'FROM/**/t;
Но для удобства чтения токены обычно разделяют пробелами:
SELECT 'a' FROM /**/ t;

Literals

There are eight kinds of literals: BOOLEAN INTEGER DOUBLE DECIMAL STRING VARBINARY MAP ARRAY.

BOOLEAN literals:
TRUE | FALSE | UNKNOWN
A literal has data type = BOOLEAN if it is the keyword TRUE or FALSE. UNKNOWN is a synonym for NULL. A literal may have type = BOOLEAN if it is the keyword NULL and there is no context to indicate a different data type.

INTEGER literals:
[plus-sign | minus-sign] digit [digit …]
or, for a hexadecimal integer literal,
[plus-sign | minus-sign] 0X | 0x hexadecimal-digit [hexadecimal-digit …]
Examples: 5, -5, +5, 55555, 0X55, 0x55
Hexadecimal 0X55 is equal to decimal 85. A literal has data type = INTEGER if it contains only digits and is in the range -9223372036854775808 to +18446744073709551615, integers outside that range are illegal.

DOUBLE literals:
[E|e [plus-sign | minus-sign] digit …]
Examples: 1E5, 1.1E5.
A literal has data type = DOUBLE if it contains «E». DOUBLE literals are also known as floating-point literals or approximate-numeric literals. To represent «Inf» (infinity), write a real numeric outside the double-precision numeric range, for example 1E309. To represent «nan» (not a number), write an expression that does not result in a real numeric, for example 0/0, using Tarantool/NoSQL. This will appear as NULL in Tarantool/SQL. In an earlier version literals containing periods were considered to be NUMBER literals. In a future version «nan» may not appear as NULL. Prior to Tarantool v. 2.10.0, digits with periods such as .0 were considered to be DOUBLE literals, but now they are considered to be DECIMAL literals.

DECIMAL literals:
[plus-sign | minus-sign] [digit [digit …]] period [digit [digit …]]
Examples: .0, 1.0, 12345678901234567890.123456789012345678
A literal has data type = DECIMAL if it contains a period, and does not contain «E». DECIMAL literals may contain up to 38 digits; if there are more, then post-decimal digits may be subject to rounding. In earlier Tarantool versions literals containing periods were considered to be NUMBER or DECIMAL literals.

STRING literals:
[quote] [character …] [quote]
Examples: 'ABC', 'AB''C'
A literal has data type type = STRING if it is a sequence of zero or more characters enclosed in single quotes. The sequence '' (two single quotes in a row) is treated as ' (a single quote) when enclosed in quotes, that is, 'A''B' is interpreted as A'B.

VARBINARY literals:
X|x [quote] [hexadecimal-digit-pair …] [quote]
Example: X'414243', which will be displayed as 'ABC'.
A literal has data type = VARBINARY («variable-length binary») if it is the letter X followed by quotes containing pairs of hexadecimal digits, representing byte values.

MAP literals:
[left curly bracket] key [colon] value [right curly bracket]
Examples: {'a':1}, {1:'a'}
A map literal is a pair of curly brackets (also called «braces») enclosing a STRING or INTEGER or UUID literal (called the map «key») followed by a colon followed by any type of literal (called the map «value»). This is a minimal form of a MAP expression.

ARRAY literals:
[left square bracket] [literal] [right square bracket]
Examples: [1], ['a']
An ARRAY literal is a literal value which is enclosed inside square brackets. This is a minimal form of an ARRAY expression.

Here are four ways to put non-ASCII characters,such as the Greek letter α alpha, in string literals:
First make sure that your shell program is set to accept characters as UTF-8. A simple way to check is
SELECT hex(cast('α' as VARBINARY)); If the result is CEB1 – which is the hexadecimal value for the UTF-8 representation of α – it is good.

  • (1) Simply enclose the character inside '...',
    'α'
  • (2) Find out what is the hexadecimal code for the UTF-8 representation of α, and enclose that inside X'...', then cast to STRING because X'...' literals are data type VARBINARY not STRING,
    CAST(X'CEB1' AS STRING)
  • (3) Find out what is the Unicode code point for α, and pass that to the CHAR function.
    CHAR(945)  /* remember that this is α as data type STRING not VARBINARY */
  • (4) Enclose statements inside double quotes and include Lua escapes, for example box.execute("SELECT '\206\177';")

One can use the concatenation operator || to combine characters made with any of these methods.

Limitations: (Issue#2344)
* LENGTH('A''B') = 3 which is correct, but on the Tarantool console the display from SELECT A''B; is A''B, which is misleading.
* It is unfortunate that X'41' is a byte sequence which looks the same as 'A', but it is not the same. box.execute("select 'A' < X'41';") is not legal at the moment. This happens because TYPEOF(X'41') yields 'varbinary'. Also it is illegal to say UPDATE ... SET string_column = X'41', one must say UPDATE ... SET string_column = CAST(X'41' AS STRING);.

Identifiers

All database objects – tables, triggers, indexes, columns, constraints, functions, collations – have identifiers. An identifier should begin with a letter or underscore ('_') and should contain only letters, digits, dollar signs ('$'), or underscores. The maximum number of bytes in an identifier is between 64982 and 65000. For compatibility reasons, Tarantool recommends that an identifier should not have more than 30 characters.

Letters in identifiers do not have to come from the Latin alphabet, for example the Japanese syllabic ひ and the Cyrillic letter д are legal. But be aware that a Latin letter needs only one byte but a Cyrillic letter needs two bytes, so Cyrillic identifiers consume a tiny amount more space.

Reserved words

Certain words are reserved and should not be used for identifiers. The simple rule is: if a word means something in Tarantool SQL syntax, do not try to use it for an identifier. The current list of reserved words is:

ALL ALTER ANALYZE AND ANY ARRAY AS ASC ASENSITIVE AUTOINCREMENT BEGIN BETWEEN BINARY BLOB BOOL BOOLEAN BOTH BY CALL CASE CAST CHAR CHARACTER CHECK COLLATE COLUMN COMMIT CONDITION CONNECT CONSTRAINT CREATE CROSS CURRENT CURRENT_DATE CURRENT_TIME CURRENT_TIMESTAMP CURRENT_USER CURSOR DATE DATETIME DEC DECIMAL DECLARE DEFAULT DEFERRABLE DELETE DENSE_RANK DESC DESCRIBE DETERMINISTIC DISTINCT DOUBLE DROP EACH ELSE ELSEIF END ESCAPE EXCEPT EXISTS EXPLAIN FALSE FETCH FLOAT FOR FOREIGN FROM FULL FUNCTION GET GRANT GROUP HAVING IF IMMEDIATE IN INDEX INNER INOUT INSENSITIVE INSERT INT INTEGER INTERSECT INTO IS ITERATE JOIN LEADING LEAVE LEFT LIKE LIMIT LOCALTIME LOCALTIMESTAMP LOOP MAP MATCH NATURAL NOT NULL NUM NUMBER NUMERIC OF ON OR ORDER OUT OUTER OVER PARTIAL PARTITION PRAGMA PRECISION PRIMARY PROCEDURE RANGE RANK READS REAL RECURSIVE REFERENCES REGEXP RELEASE RENAME REPEAT REPLACE RESIGNAL RETURN REVOKE RIGHT ROLLBACK ROW ROWS ROW_NUMBER SAVEPOINT SCALAR SELECT SENSITIVE SEQSCAN SESSION SET SIGNAL SIMPLE SMALLINT SPECIFIC SQL START STRING SYSTEM TABLE TEXT THEN TO TRAILING TRANSACTION TRIGGER TRIM TRUE TRUNCATE UNION UNIQUE UNKNOWN UNSIGNED UPDATE USER USING UUID VALUES VARBINARY VARCHAR VIEW WHEN WHENEVER WHERE WHILE WITH

Identifiers may be enclosed in double quotes. These are called quoted identifiers or «delimited identifiers» (unquoted identifiers may be called «regular identifiers»). The double quotes are not part of the identifier. A delimited identifier may be a reserved word and may contain any printable character. Tarantool converts letters in regular identifiers to upper case before it accesses the database, so for statements like CREATE TABLE a (a INTEGER PRIMARY KEY); or SELECT a FROM a; the table name is A and the column name is A. However, Tarantool does not convert delimited identifiers to upper case, so for statements like CREATE TABLE "a" ("a" INTEGER PRIMARY KEY); or SELECT "a" FROM "a"; the table name is a and the column name is a. The sequence "" is treated as " when enclosed in double quotes, that is, "A""B" is interpreted as "A"B".

Examples: things, t45, journal_entries_for_2017, ддд, "into"

Внутри некоторых инструкций к идентификаторам можно добавлять квалификаторы для исключения двусмысленности. Квалификатор — это идентификатор объекта более высокого уровня, за которым следует точка. Например, к столбцу column1 в таблице table1 можно обратиться как table1.column1. Идентификатор, в том числе с добавленным квалификатором, — своего рода имя объекта. Например, в SELECT table1.column1, table2.column1 FROM table1, table2; соответствующие квалификаторы дают понять, что первый используемый столбец — это column1 из table1, а второй — column1 из table2.

The rules are sometimes relaxed for compatibility reasons, for example some non-letter characters such as $ and « are legal in regular identifiers. However, it is better to assume that rules are never relaxed.

The following are examples of legal and illegal identifiers.

_A1   -- legal, begins with underscore and contains underscore | letter | digit
1_A   -- illegal, begins with digit
A$« -- legal, but not recommended, try to stick with digits and letters and underscores
+ -- illegal, operator token
grant -- illegal, GRANT is a reserved word
"grant" -- legal, delimited identifiers may be reserved words
"_space" -- legal, but Tarantool already uses this name for a system space
"A"."X" -- legal, for columns only, inside statements where qualifiers may be necessary
'a' -- illegal, single quotes are for literals not identifiers
A123456789012345678901234567890 -- legal, identifiers can be long
ддд -- legal, and will be converted to upper case in identifiers

The following example shows that conversion to upper case affects regular identifiers but not delimited identifiers.

CREATE TABLE "q" ("q" INTEGER PRIMARY KEY);
SELECT * FROM q;
-- Result = "error: 'no such table: Q'.

Operands

An operand is something that can be operated on. Literals and column identifiers are operands. So are NULL and DEFAULT.

NULL and DEFAULT are keywords which represent values whose data types are not known until they are assigned or compared, so they are known by the technical term «contextually typed value specifications». (Exception: for the non-standard statement «SELECT NULL FROM table-name;» NULL has data type BOOLEAN.)

Operand data types

Every operand has a data type.

For literals, as seen earlier, the data type is usually determined by the format.

For identifiers, the data type is usually determined by the definition.

The usual determination may change because of context or because of explicit casting.

For some SQL data type names there are aliases. An alias may be used for data definition. For example VARCHAR(5) and TEXT are aliases of STRING and may appear in CREATE TABLE table_name (column_name VARCHAR(5) PRIMARY KEY); but Tarantool, if asked, will report that the data type of column_name is STRING.

For every SQL data type there is a corresponding NoSQL type, for example an SQL STRING is stored in a NoSQL space as type = „string“.

To avoid confusion in this manual, all references to SQL data type names are in upper case and all similar words which refer to NoSQL types or to other kinds of object are in lower case, for example:

  • STRING is a data type name, but string is a general term;
  • NUMBER — имя типа данных, а «numeric» и «числовое значение» — общие термины.

Although it is common to say that a VARBINARY value is a «binary string», this manual will not use that term and will instead say «byte sequence».

Here are all the SQL data types, their corresponding NoSQL types, their aliases, and minimum / maximum literal examples.

SQL type NoSQL type Aliases Minimum Maximum
BOOLEAN boolean (логический) BOOL FALSE TRUE
INTEGER integer (целое число) INT -9223372036854775808 18446744073709551615
UNSIGNED unsigned (none) 0 18446744073709551615
DOUBLE double (числа с двойной точностью) (none) -1.79769e308 1.79769e308
NUMBER number (none) -1.79769e308 1.79769e308
DECIMAL decimal DEC -9999999999999999999
9999999999999999999		 9999999999999999999
9999999999999999999
STRING строка TEXT, VARCHAR(n) '' 'many-characters'
VARBINARY varbinary (none) X'' X'many-hex-digits'
UUID uuid (none) 00000000-0000-0000-
0000-000000000000		 ffffffff-ffff-ffff-
dfff-ffffffffffff
DATETIME datetime (none)    
INTERVAL interval (none)    
SCALAR (различные) (none) FALSE максимальное значение UUID
MAP map (none) {} {big-key:big-value}
ARRAY array (none) [] [many values]
ANY any (none) FALSE [many values]

BOOLEAN values are FALSE, TRUE, and UNKNOWN (which is the same as NULL). FALSE is less than TRUE.

Значения INTEGER — это числовые значения, которые не содержат десятичной точки и не представлены в экспоненциальной форме записи. Возможные значения: от -2^63 до +2^64, а также NULL.

Значения UNSIGNED — это числовые значения, которые не содержат десятичной точки и не представлены в экспоненциальной форме записи. Возможные значения: от 0 до +2^64, а также NULL.

Значения DOUBLE — это числовые значения, которые содержат десятичную точку (например, 0.5) или представлены в экспоненциальной форме записи (например, 5E-1). Диапазон возможных значений соответствует стандарту IEEE 754 чисел с плавающей точкой, а также включает в себя NULL. Числа, выходящие за пределы диапазона DOUBLE, могут быть представлены как -inf или inf.

Значения NUMBER имеют тот же диапазон, что и значения DOUBLE, но могут быть и целыми числами. Для NUMBER не существует отдельного формата записи (значения типа 1.5 или 1E555 считаются DOUBLE), поэтому при необходимости используйте CAST, чтобы привести значение к типу NUMBER. См. также описание типа „number“ в NoSQL. Арифметические операции и встроенные арифметические функции с типами NUMBER не поддерживаются начиная с версии Tarantool 2.10.1.

DECIMAL values can contain up to 38 digits on either side of a decimal point. and any arithmetic with DECIMAL values has exact results (arithmetic with DOUBLE values could have approximate results instead of exact results). Before Tarantool v. 2.10.0 there was no literal format for DECIMAL, so it was necessary to use CAST to insist that a numeric has data type DECIMAL, for example CAST(1.1 AS DECIMAL) or CAST('99999999999999999999999999999999999999' AS DECIMAL). See the description of NoSQL type „decimal“. DECIMAL support in SQL was added in Tarantool version 2.10.1.

STRING values are any sequence of zero or more characters encoded with UTF-8, or NULL. The possible character values are the same as for the Unicode standard. Byte sequences which are not valid UTF-8 characters are allowed but not recommended. STRING literal values are enclosed within single quotes, for example 'literal'. If the VARCHAR alias is used for column definition, it must include a maximum length, for example column_1 VARCHAR(40). However, the maximum length is ignored. The data-type may be followed by [COLLATE collation-name].

VARBINARY values are any sequence of zero or more octets (bytes), or NULL. VARBINARY literal values are expressed as X followed by pairs of hexadecimal digits enclosed within single quotes, for example X'0044'. VARBINARY’s NoSQL equivalent is 'varbinary' but not character string – the MessagePack storage is MP_BIN (MsgPack binary).

Значения UUID (универсальные уникальные идентификаторы) — это 32 шестнадцатеричные цифры или NULL. Обычный формат UUID это строка, разделённая дефисами на пять групп в формате 8-4-4-4-12, например, '000024ac-7ca6-4ab2-bd75-34742ac91213'. В MessagePack (расширение MP_EXT) для хранения UUID требуется 16 байт. Значения UUID могут быть созданы с помощью модуля uuid Tarantool/NoSQL или c помощью функций UUID(). Поддержка UUID в SQL была добавлена в версии Tarantool 2.9.1.

DATETIME. Introduced in v. 2.10.0. A datetime table field can be created by using this type, which is semantically equivalent to the standard TIMESTAMP WITH TIME ZONE type.

tarantool> create table T2(d datetime primary key);
---
- row_count: 1
...

tarantool> insert into t2 values ('2022-01-01');
---
- null
- 'Type mismatch: can not convert string(''2022-01-01'') to datetime'
...

tarantool> insert into t2 values (cast('2022-01-01' as datetime));
---
- row_count: 1
...

tarantool> select * from t2;
---
- metadata:
  - name: D
    type: datetime
  rows:
  - ['2022-01-01T00:00:00Z']
...

There is no implicit cast available from a string expression to a datetime expression (unlike convention used by majority of SQL vendors). In such cases, you need to use explicit cast from a string value to a datetime value (see the example above).

You can subtract datetime and datetime, datetime and interval, or add datetime and interval in any order (see examples of such arithmetic in the description of the INTERVAL type).

The built-in functions related to the DATETIME type are DATE_PART() and NOW()

INTERVAL. Introduced in v. 2.10.0. Similarly to the DATETIME type, you can define a column of the INTERVAL type.

tarantool> create table T(d datetime primary key, i interval);
---
- row_count: 1
...

tarantool> insert into T values (cast('2022-02-02T01:01' as datetime), cast({'year': 1, 'month': 1} as interval));
---
- row_count: 1
...

tarantool> select * from t;
---
- metadata:
  - name: D
    type: datetime
  - name: I
    type: interval
  rows:
  - ['2022-02-02T01:01:00Z', '+1 years, 1 months']
...

Unlike DATETIME, INTERVAL cannot be a part of an index.

There is no implicit cast available for conversions to an interval from a string or any other type. But there is explicit cast allowed from maps (see examples below).

Intervals can be used in arithmetic operations like + or - only with the datetime expression or another interval:

tarantool> select * from t
---
- metadata:
  - name: D
    type: datetime
  - name: I
    type: interval
  rows:
  - ['2022-02-02T01:01:00Z', '+1 years, 1 months']
...

tarantool> select d, d + i, d + cast({'year': 1, 'month': 2} as interval) from t
---
- metadata:
  - name: D
    type: datetime
  - name: COLUMN_1
    type: datetime
  - name: COLUMN_2
    type: datetime
  rows:
  - ['2022-02-02T01:01:00Z', '2023-03-02T01:01:00Z', '2023-04-02T01:01:00Z']
...

tarantool> select i + cast({'year': 1, 'month': 2} as interval) from t
---
- metadata:
  - name: COLUMN_1
    type: interval
  rows:
  - ['+2 years, 3 months']
...

There is the predefined list of known attributes for the map if you want to convert one to the INTERVAL expression:

  • year
  • month
  • week
  • day
  • hour
  • minute
  • second
  • nsec
tarantool> select cast({'year': 1, 'month': 1, 'week': 1, 'day': 1, 'hour': 1, 'min': 1, 'sec': 1} as interval)
---
- metadata:
  - name: COLUMN_1
    type: interval
  rows:
  - ['+1 years, 1 months, 1 weeks, 1 days, 1 hours, 1 minutes, 1 seconds']
...

tarantool> \set language lua


tarantool> v = {year = 1, month = 1, week = 1, day = 1, hour = 1,
         >      min = 1, sec = 1, nsec = 1, adjust = 'none'}
---
...

tarantool> box.execute('select cast(#v as interval);', {{['#v'] = v}})

---
- metadata:
  - name: COLUMN_1
    type: interval
  rows:
  - ['+1 years, 1 months, 1 weeks, 1 days, 1 hours, 1 minutes, 1.000000001 seconds']
...

SCALAR может использоваться в определениях столбцов. Отдельные значения столбца также могут иметь тип SCALAR. Подробную информацию вы найдете в разделе Определение столбцов — правила для типа данных SCALAR. Вместе с этим типом данных может использоваться [COLLATE название-сортировки]. До версии Tarantool 2.10.1 отдельные значения столбцов могли иметь один из перечисленных выше типов: BOOLEAN, INTEGER, DOUBLE, DECIMAL, STRING, VARBINARY или UUID. Начиная с версии Tarantool 2.10.1 все значения в столбце SCALAR имеют тип SCALAR.

MAP values are key:value combinations which can be produced with MAP expressions. Maps cannot be used in arithmetic or comparison (except IS [NOT] NULL), and the only functions where they are allowed are CAST, QUOTE, TYPEOF, and functions involving NULL comparisons.

ARRAY values are lists which can be produced with ARRAY expressions. Arrays cannot be used in arithmetic or comparison (except IS [NOT] NULL), and the only functions where they are allowed are CAST, QUOTE, TYPEOF, and functions involving NULL comparisons.

ANY can be used for column definitions and the individual column values have type ANY. The difference between SCALAR and ANY is:

  • SCALAR columns may not contain MAP or ARRAY values, but ANY columns may contain them.
  • SCALAR values are comparable, while ANY values are not comparable.

Any value of any data type may be NULL. Ordinarily NULL will be cast to the data type of any operand it is being compared to or to the data type of the column it is in. If the data type of NULL cannot be determined from context, it is BOOLEAN.

Most of the SQL data types correspond to Tarantool/NoSQL types with the same name. In Tarantool versions before v. 2.10.0, There were also some Tarantool/NoSQL data types which had no corresponding SQL data types. In those versions, if Tarantool/SQL reads a Tarantool/NoSQL value of a type that has no SQL equivalent, Tarantool/SQL could treat it as NULL or INTEGER or VARBINARY. For example, SELECT "flags" FROM "_vspace"; would return a column whose type is 'map'. Such columns can only be manipulated in SQL by invoking Lua functions.

Operators

An operator signifies what operation can be performed on operands.

Almost all operators are easy to recognize because they consist of one-character or two-character non-alphabetic tokens, except for six keyword operators (AND IN IS LIKE NOT OR).

Almost all operators are «dyadic», that is, they are performed on a pair of operands – the only operators that are performed on a single operand are NOT and ~ and (sometimes) -.

The result of an operation is a new operand. If the operator is a comparison operator then the result has data type BOOLEAN (TRUE or FALSE or UNKNOWN). Otherwise the result has the same data type as the original operands, except that: promotion to a broader type may occur to avoid overflow. Arithmetic with NULL operands will result in a NULL operand.

В списке операторов ниже пометка «(арифметическая операция)» указывает на то, что все операнды должны быть числовыми значениями (кроме NUMBER) и в результате тоже должно получиться число. Пометка «(сравнение)» указывает, что операнды должны иметь схожие типы данных и результат будет типа BOOLEAN. Пометка «(логическая операция)» указывает, что операнды должны быть типа BOOLEAN и результат также будет типа BOOLEAN. Если операция невозможна, выбрасывается исключение. Кроме того, существуют особые ситуации: их описание приводится после списка операторов. На месте указанных в примерах конкретных значений (литералов) могут с тем же успехом стоять идентификаторы столбцов.

Начиная с версии Tarantool 2.10.1 арифметические операнды не могут быть типа NUMBER.

  • + addition (arithmetic)

    Add two numerics according to standard arithmetic rules. Example: 1 + 5, result = 6.

  • - subtraction (arithmetic)

    Subtract second numeric from first numeric according to standard arithmetic rules.

    Example: 1 - 5, result = -4.

  • * multiplication (arithmetic)

    Multiply two numerics according to standard arithmetic rules.

    Example: 2 * 5, result = 10.

  • / division (arithmetic)

    Divide second numeric into first numeric according to standard arithmetic rules. Division by zero is not legal. Division of integers always results in rounding toward zero, use CAST to DOUBLE or to DECIMAL to get non-integer results.

    Example: 5 / 2, result = 2.

  • % modulus (arithmetic)

    Divide second numeric into first numeric according to standard arithmetic rules. The result is the remainder. Starting with Tarantool version 2.10.1, operands must be INTEGER or UNSIGNED.

    Examples: 17 % 5, result = 2; -123 % 4, result = -3.

  • << shift left (arithmetic)

    Shift the first numeric to the left N times, where N = the second numeric. For positive numerics, each 1-bit shift to the left is equivalent to multiplying times 2.

    Example: 5 << 1, result = 10.

    Примечание

    Starting with Tarantool version 2.10.1, operands must be non-negative INTEGER or UNSIGNED.

  • >> shift right (arithmetic)

    Shift the first numeric to the right N times, where N = the second numeric. For positive numerics, each 1-bit shift to the right is equivalent to dividing by 2.

    Example: 5 >> 1, result = 2.

    Примечание

    Starting with Tarantool version 2.10.1, operands must be non-negative INTEGER or UNSIGNED.

  • & and (arithmetic)

    Combine the two numerics, with 1 bits in the result if and only if both original numerics have 1 bits.

    Example: 5 & 4, result = 4.

    Примечание

    Starting with Tarantool version 2.10.1, operands must be non-negative INTEGER or UNSIGNED.

  • | or (arithmetic)

    Combine the two numerics, with 1 bits in the result if either original numeric has a 1 bit.

    Example: 5 | 2, result = 7.

    Примечание

    Starting with Tarantool version 2.10.1, operands must be non-negative INTEGER or UNSIGNED.

  • ~ negate (arithmetic), sometimes called bit inversion

    Change 0 bits to 1 bits, change 1 bits to 0 bits.

    Example: ~5, result = -6.

    Примечание

    Starting with Tarantool version 2.10.1, the operand must be non-negative INTEGER or UNSIGNED.

  • < less than (comparison)

    Return TRUE if the first operand is less than the second by arithmetic or collation rules.

    Example for numerics: 5 < 2, result = FALSE

    Example for strings: 'C' < ' ', result = FALSE

  • <= less than or equal (comparison)

    Return TRUE if the first operand is less than or equal to the second by arithmetic or collation rules.

    Example for numerics: 5 <= 5, result = TRUE

    Example for strings: 'C' <= 'B', result = FALSE

  • > greater than (comparison)

    Return TRUE if the first operand is greater than the second by arithmetic or collation rules.

    Example for numerics: 5 > -5, result = TRUE

    Example for strings: 'C' > '!', result = TRUE

  • >= greater than or equal (comparison)

    Return TRUE if the first operand is greater than or equal to the second by arithmetic or collation rules.

    Example for numerics: 0 >= 0, result = TRUE Example for strings: 'Z' >= 'Γ', result = FALSE

  • = equal (assignment or comparison)

    After the word SET, «=» means the first operand gets the value from the second operand. In other contexts, «=» returns TRUE if operands are equal.

    Example for assignment: ... SET column1 = 'a';

    Example for numerics: 0 = 0, result = TRUE

    Example for strings: '1' = '2 ', result = FALSE

  • == equal (assignment), or equal (comparison)

    This is a non-standard equivalent of «= equal (assignment or comparison)».

  • <> not equal (comparison)

    Return TRUE if the first operand is not equal to the second by arithmetic or collation rules.

    Example for strings: 'A' <> 'A     ' is TRUE.

  • != not equal (comparison)

    This is a non-standard equivalent of «<> not equal (comparison)».

  • [ , ] (indexed access operator)

    Array example: ['a', 'b', 'c'] [2] (returns 'b')

    Map example: {'a' : 123, 7: 'asd'}['a'] (returns 123)

    See also: ARRAY index expression and MAP index expression.

  • IS NULL and IS NOT NULL (comparison)

    For IS NULL: Return TRUE if the first operand is NULL, otherwise return FALSE. Example: column1 IS NULL, result = TRUE if column1 contains NULL.

    For IS NOT NULL: Return FALSE if the first operand is NULL, otherwise return TRUE. Example: column1 IS NOT NULL, result = FALSE if column1 contains NULL.

  • LIKE (comparison)

    Perform a comparison of two string operands. If the second operand contains '_', the '_' matches any single character in the first operand. If the second operand contains '%', the '%' matches 0 or more characters in the first operand. If it is necessary to search for either '_' or '%' within a string without treating it specially, an optional clause can be added, ESCAPE single-character-operand, for example 'abc_' LIKE 'abcX_' ESCAPE 'X' is TRUE because X' means «following character is not special». Matching is also affected by the string’s collation.

  • BETWEEN (comparison)

    x BETWEEN y AND z is shorthand for x >= y AND x <= z.

  • NOT negation (logic)

    Return TRUE if operand is FALSE return FALSE if operand is TRUE, else return UNKNOWN.

    Example: NOT (1 > 1), result = TRUE.

  • IN is equal to one of a list of operands (comparison)

    Return TRUE if first operand equals any of the operands in a parenthesized list.

    Example: 1 IN (2,3,4,1,7), result = TRUE.

  • AND and (logic)

    Return TRUE if both operands are TRUE. Return UNKNOWN if both operands are UNKNOWN. Return UNKNOWN if one operand is TRUE and the other operand is UNKNOWN. Return FALSE if one operand is FALSE and the other operand is (UNKNOWN or TRUE or FALSE).

  • OR or (logic)

    Return TRUE if either operand is TRUE. Return FALSE if both operands are FALSE. Return UNKNOWN if one operand is UNKNOWN and the other operand is (UNKNOWN or FALSE).

  • || concatenate (string manipulation)

    Return the value of the first operand concatenated with the value of the second operand.

    Example: 'A' || 'B', result = 'AB'.

The precedence of dyadic operators is:

||
* / %
+ -
<< >> & |
<  <= > >=
=  == != <> IS IS NOT IN LIKE
AND
OR

To ensure a desired precedence, use () parentheses.

Special situations

If one of the operands has data type DOUBLE, Tarantool uses floating-point arithmetic. This means that exact results are not guaranteed and rounding may occur without warning. For example, 4.7777777777777778 = 4.7777777777777777 is TRUE.

The floating-point values inf and -inf are possible. For example, SELECT 1e318, -1e318; will return «inf, -inf». Arithmetic on infinite values may cause NULL results, for example SELECT 1e318 - 1e318; is NULL and SELECT 1e318 * 0; is NULL.

SQL operations never return the floating-point value -nan, although it may exist in data created by Tarantool’s NoSQL. In SQL, -nan is treated as NULL.

В предыдущих версиях Tarantool строка преобразовывалась в числовое значение, если она использовалась с арифметическим оператором и преобразование было возможно. Например, результатом выражения '7' + '7' было 14. Для операций сравнения строка '7' преобразовывалась в значение 7. Это называется неявным приведением. Оно было применимо для значений типа STRING и всех числовых типов данных. Начиная с версии Tarantool 2.10 неявное приведение в числа больше не поддерживается.

Ограничения (подробнее в Issue#2346 на GitHub):
* Некоторые ключевые слова, например MATCH и REGEXP, зарезервированы, но в текущих или будущих версиях Tarantool их пока не планируется использовать.
* 99999999999999999 << 210 возвращает 0.

Expressions

An expression is a chunk of syntax that causes return of a value. Expressions may contain literals, column-names, operators, and parentheses.

Therefore these are examples of expressions: 1, 1 + 1 << 1, (1 = 2) OR 4 > 3, 'x' || 'y' || 'z'.

Also there are two expressions that involve keywords:

  • value IS [NOT] NULL: determine whether value is (not) NULL.
  • CASE ... WHEN ... THEN ... ELSE ... END: set a series of conditions.

ARRAY expressions

Usage: [ value ... ]

Examples: [1,2,3,4], [1,[2,3],4], ['a', "column_1", uuid()]

An expression has data type = ARRAY if it is a sequence of zero or more values enclosed in square brackets ([ and ]). Often the values in the sequence are called «elements». The element data type may be anything, including ARRAY – that is, ARRAYs may be nested. Different elements may have different types. The Lua equivalent type is „array“.

MAP expressions

Usage: { key : value }

Literal examples: {'a':1}, { "column_1" : X'1234' }

Non-literal examples: {"a":"a"}, {UUID(): (SELECT 1) + 1}, {1:'a123', 'two':uuid()}

An expression has data type = MAP if it is enclosed in curly brackets (also called braces) { and } and contains a key for identification, then a colon :, then a value for what the key identifies. The key data type must be INTEGER or STRING or UUID. The value data type may be anything, including MAP – that is, MAPs may be nested. The Lua equivalent type is „map“ but the syntax is slightly different, for example the SQL value {'a': 1} is represented in Lua as {a = 1}.

ARRAY index expression

Usage: array-value [square bracket] index [square bracket]

Example: ['a', 'b', 'c'] [2] (this returns „b“)

As in other languages, an element of an array can be referenced with an integer inside square brackets. The returned value is of type ANY.

The SELECT query below retrieves all score values stored in the second position of the scores array field:

CREATE TABLE plays (user_id INTEGER PRIMARY KEY, scores ARRAY);
INSERT INTO plays VALUES (1, [23, 17, 55, 48]);
INSERT INTO plays VALUES (2, [12, 8, 20, 33]);
SELECT scores[2] FROM plays;
/* ---
  rows:
  - [17]
  - [8]
... */

MAP index expression

Usage: map-value [square bracket] index [square bracket]

Example: {'a' : 123, 7: 'asd'}['a'] (this returns 123). The returned value is of type ANY.

The SELECT query below retrieves all values stored in the name attribute of the info map field:

CREATE TABLE bands (id INTEGER PRIMARY KEY, info MAP);
INSERT INTO bands VALUES (1, {'name': 'The Beatles', 'year': 1960});
INSERT INTO bands VALUES (2, {'name': 'The Doors', 'year': 1965});
SELECT info['name'] FROM bands;
/* ---
  rows:
  - ['The Beatles']
  - ['The Doors']
... */

See also: subquery.

Comparing and ordering

Определить, равны ли два значения или первое больше/меньше второго, помогают специальные правила. Они применяются при поиске, сортировке результатов в порядке возрастания значений в столбце, а также определении уникальности содержимого столбца. Результатом сравнения могут быть три значения типа BOOLEAN: TRUE, FALSE или UNKNOWN. В любом сравнении, где ни один из операндов не является NULL, операнды считаются различными, если результат сравнения равен FALSE. Любой набор операндов, где все операнды отличаются друг от друга, считается уникальным.

Сравнение двух числовых значений:
* infinity = infinity вернет TRUE;
* обычные числовые значения сравниваются по обычным арифметическим правилам.

When comparing any value to NULL:
(for examples in this paragraph assume that column1 in table T contains {NULL, NULL, 1, 2})
* value comparison-operator NULL is UNKNOWN (not TRUE and not FALSE), which affects «WHERE condition» because the condition must be TRUE, and does not affect «CHECK (condition)» because the condition must be either TRUE or UNKNOWN. Therefore SELECT * FROM T WHERE column1 > 0 OR column1 < 0 OR column1 = 0; returns only {1,2}, and the table can have been created with CREATE TABLE T (… column1 INTEGER, CHECK (column1 >= 0));
* for any operations that contain the keyword DISTINCT, NULLs are not distinct. Therefore SELECT DISTINCT column1 FROM T; will return {NULL,1,2}.
* for grouping, NULL values sort together. Therefore SELECT column1, COUNT(*) FROM T GROUP BY column1; will include a row {NULL, 2}.
* for ordering, NULL values sort together and are less than non-NULL values. Therefore SELECT column1 FROM T ORDER BY column1; returns {NULL, NULL, 1,2}.
* for evaluating a UNIQUE constraint or UNIQUE index, any number of NULLs is okay. Therefore CREATE UNIQUE INDEX i ON T (column1); will succeed.

When comparing any value (except an ARRAY or MAP or ANY) to a SCALAR:
* This is always legal, and the result depends on the underlying type of the value. For example, if COLUMN1 is defined as SCALAR, and a value in the column is „a“, then COLUMN1 < 5 is a legal comparison and the result is FALSE because numeric is less than STRING.

Сравнение числового значения со значением типа STRING:
* Сравнение разрешено, если значение STRING можно явно привести к числовому.

When comparing a BOOLEAN to a BOOLEAN:
TRUE is greater than FALSE.

When comparing a VARBINARY to a VARBINARY:
* The numeric value of each pair of bytes is compared until the end of the byte sequences or until inequality. If two byte sequences are otherwise equal but one is longer, then the longer one is greater.

When comparing for the sake of eliminating duplicates:
* This is usually signalled by the word DISTINCT, so it applies to SELECT DISTINCT, to set operators such as UNION (where DISTINCT is implied), and to aggregate functions such as AVG(DISTINCT).
* Two operators are «not distinct» if they are equal to each other, or are both NULL
* If two values are equal but not identical, for example 1.0 and 1.00, they are non-distinct and there is no way to specify which one will be eliminated
* Values in primary-key or unique columns are distinct due to definition.

When comparing a STRING to a STRING:
* Ordinarily collation is «binary», that is, comparison is done according to the numeric values of the bytes. This can be cancelled by adding a COLLATE clause at the end of either expression. So 'A' < 'a' and 'a' < 'Ä', but 'A' COLLATE "unicode_ci" = 'a' and 'a' COLLATE "unicode_ci" = 'Ä'.
* When comparing a column with a string literal, the column’s defined collation is used.
* Ordinarily trailing spaces matter. So 'a' = 'a  ' is not TRUE. This can be cancelled by using the TRIM(TRAILING …) function.

When comparing any value to an ARRAY or MAP or ANY:
* The result is an error.

Ограничения:
* Ожидается, что при работе с VARBINARY не будет применяться LIKE.

Statements

Инструкция (statement) состоит из ключевых слов и выражений языка SQL, которые предписывают Tarantool выполнять какие-либо действия с базой данных. Инструкции начинаются с одного из ключевых слов: ALTER, ANALYZE, COMMIT, CREATE, DELETE, DROP, EXPLAIN, INSERT, PRAGMA, RELEASE, REPLACE, ROLLBACK, SAVEPOINT, SELECT, SET, START, TRUNCATE, UPDATE, VALUES или WITH. В конце инструкции ставится точка с запятой ;, хотя это и не является обязательным.

A client sends a statement to the Tarantool server. The Tarantool server parses the statement and executes it. If there is an error, Tarantool returns an error message.

Data Type Conversion

Data type conversion, also called casting, is necessary for any operation involving two operands X and Y, when X and Y have different data types.
Or, casting is necessary for assignment operations (when INSERT or UPDATE is putting a value of type X into a column defined as type Y).
Casting can be «explicit» when a user uses the CAST function, or «implicit» when Tarantool does a conversion automatically.

The general rules are fairly simple:
Assignments and operations involving NULL cause NULL or UNKNOWN results.
For arithmetic, convert to the data type which can contain both operands and the result.
For explicit casts, if a meaningful result is possible, the operation is allowed.
For implicit casts, if a meaningful result is possible and the data types on both sides are either STRINGs or most numeric types (that is, are STRING or INTEGER or UNSIGNED or DOUBLE or DECIMAL but not NUMBER), the operation is sometimes allowed.

The specific situations in this chart follow the general rules:

~                В BOOLEAN  | В число    | В STRING  | В VARBINARY  | В UUID
---------------  ----------   ----------   ---------   ------------   -------
Из BOOLEAN     | AAA        | ---        | A--       | ---          | ---
Из числа       | ---        | SSA        | A--       | ---          | ---
Из STRING      | S--        | S--        | AAA       | A--          | S--
Из VARBINARY   | ---        | ---        | A--       | AAA          | S--
Из UUID        | ---        | ---        | A--       | A--          | AAA

Where each entry in the chart has 3 characters:
Where A = Always allowed, S = Sometimes allowed, - = Never allowed.
The first character of an entry is for explicit casts,
the second character is for implicit casts for assignment,
the third character is for implicit cast for comparison.
So AAA = Always for explicit, Always for Implicit (assignment), Always for Implicit (comparison).

The S «Sometimes allowed» character applies for these special situations:
From STRING To BOOLEAN is allowed if UPPER(string-value) = 'TRUE' or 'FALSE'.
From numeric to INTEGER or UNSIGNED is allowed for cast and assignment only if the result is not out of range, and the numeric has no post-decimal digits.
From STRING to INTEGER or UNSIGNED or DECIMAL is allowed only if the string has a representation of a numeric, and the result is not out of range, and the numeric has no post-decimal digits.
From STRING to DOUBLE or NUMBER is allowed only if the string has a representation of a numeric.
From STRING to UUID is allowed only if the value is (8 hexadecimal digits) hyphen (4 hexadecimal digits) hyphen (4 hexadecimal digits) hyphen (4 hexadecimal digits) hyphen (12 hexadecimal digits), such as '8e3b281b-78ad-4410-bfe9-54806a586a90'.
From VARBINARY to UUID is allowed only if the value is 16 bytes long, as in X'8e3b281b78ad4410bfe954806a586a90'.

The chart does not show To|From SCALAR because the conversions depend on the type of the value, not the type of the column definition. Explicit cast to SCALAR is always allowed.

The chart does not show To|From ARRAY or MAP or ANY because almost no conversions are possible. Explicit cast to ANY, or casting any value to its original data type, is legal, but that is all. This is a slight change: before Tarantool v. 2.10.0, it was legal to cast such values as VARBINARY. It is still possible to use arguments with these types in QUOTE functions, which is a way to convert them to STRINGs.

Примечание

Since version 2.4.1, the NUMBER type is processed in the same way as the number type in NoSQL Tarantool.

Начиная с версии Tarantool 2.10.1 недопустимы некоторые преобразования, которые раньше были разрешены:
Явное приведение числового типа к BOOLEAN.
Явное приведение BOOLEAN к числовому типу.
Неявное приведение NUMBER к другим числовым типам при выполнении арифметических или встроенных функций.
Неявное приведение числового типа к STRING.
Неявное приведение STRING к числовому типу.

Examples of casts, illustrating the situations in the chart:

Выполнение CAST(TRUE AS STRING) допустимо. В строке «Из BOOLEAN», столбце «В STRING» приведенной выше таблицы стоит значение A--, где буква A относится к явному приведению и означает «Always Allowed» — всегда разрешено. Таким образом, результатом операции будет 'TRUE'.

Выполнение UPDATE ... SET varbinary_column = 'A' завершится ошибкой. В строке «Из STRING», столбце «В VARBINARY» приведенной выше таблицы стоит значение A--, где второй символ - относится к неявному приведению при присваивании и` означает «не разрешено». Результатом будет сообщение об ошибке.

Выражение 1.7E-1 > 0 допустимо. В строке «Из числа», столбце «В число» приведенной выше таблицы стоит значение SSA, где третья буква А относится к неявному приведению при сравнении и означает «Always Allowed» — всегда разрешено. Таким образом, результатом операции будет 'TRUE'.

Выполнение 11 > '2' завершится ошибкой. В строке «Из числа», столбце «В STRING» приведенной выше таблицы стоит значение A--, где третий символ - относится к неявному приведению при сравнении и` означает «не разрешено». Результатом операции будет сообщение об ошибке. Подробное объяснение приводится ниже.

Выполнение CAST('5' AS INTEGER) допустимо. В строке «Из STRING», столбце «В число» приведенной выше таблицы стоит значение S--, где первая буква S относится к явному приведению и означает «Sometimes allowed» — иногда разрешено. При этом приведение CAST('5.5' AS INTEGER) завершится ошибкой, поскольку это не целое число. Если число содержит цифры после десятичной точки, а целевой тип приведения — INTEGER или UNSIGNED, присвоение не будет выполнено.

Implicit string/numeric cast

Примеры в этом разделе справедливы только для версий Tarantool до 2.10. Начиная с Tarantool 2.10 неявное приведение строк и числовых значений больше не допускается.

Приведение STRING к INTEGER/DOUBLE/NUMBER/UNSIGNED (любому числовому типу) и наоборот, выполняемое в ходе операции присвоения или сравнения, может требовать особых условий.

1 = '1' /* сравнение значения STRING с числовым значением */
UPDATE ... SET string_column = 1 /* запись в STRING числового значения */

Для операций сравнения всегда выполняется приведение STRING к числовому значению.
Поэтому 1e2 = '100' вернет TRUE, как и 11 > '2'.
Если приведение не удалось, числовое значение считается меньше, чем значение типа STRING.
Так что 1e400 < '' тоже вернет TRUE.
Исключение: для оператора BETWEEN приведение производится к типу данных первого и последнего операндов.
Поэтому выражение '66' BETWEEN 5 AND '7' вернет TRUE.

Начиная с Tarantool 2.5.1 действует измененный алгоритм присваивания. В связи с этим неявные приведения строк к числам недопустимы. Например, INSERT INTO t (integer_column) VALUES ('5'); выдаст ошибку.

Implicit cast does happen if STRINGS are used in arithmetic.
Therefore '5' / '5' = 1. If the cast fails, then the result is an error.
Therefore '5' / '' is an error.

Неявное приведение не производится, если числовые значения используются в конкатенации или в LIKE.
Поэтому выражение 5 || '5' недопустимо.

In the following examples, implicit cast does not happen for values in SCALAR columns:
DROP TABLE scalars;
CREATE TABLE scalars (scalar_column SCALAR PRIMARY KEY);
INSERT INTO scalars VALUES (11), ('2');
SELECT * FROM scalars WHERE scalar_column > 11;   /* 0 rows. So 11 > '2'. */
SELECT * FROM scalars WHERE scalar_column < '2';  /* 1 row. So 11 < '2'. */
SELECT max(scalar_column) FROM scalars; /* 1 row: '2'. So 11 < '2'. */
SELECT sum(scalar_column) FROM scalars; /* 1 row: 13. So cast happened. */
These results are not affected by indexing, or by reversing the operands.

Implicit cast does NOT happen for GREATEST() or LEAST(). Therefore LEAST('5',6) is 6.

For function arguments:
If the function description says that a parameter has a specific data type, and implicit assignment casts are allowed, then arguments which are not passed with that data type will be converted before the function is applied.
For example, the LENGTH() function expects a STRING or VARBINARY, and INTEGER can be converted to STRING, therefore LENGTH(15) will return the length of '15', that is, 2.
But implicit cast sometimes does NOT happen for parameters. Therefore ABS('5') will cause an error message after Issue#4159 is fixed. However, TRIM(5) will still be legal.

Although it is not a requirement of the SQL standard, implicit cast is supposed to help compatibility with other DBMSs. However, other DBMSs have different rules about what can be converted (for example they may allow assignment of 'inf' but disallow comparison with '1e5'). And, of course, it is not possible to be compatible with other DBMSs and at the same time support SCALAR, which other DBMSs do not have.

SQL statements and clauses

The Statements and Clauses guide shows all Tarantool/SQL statements“ syntax and use.

Heading Введение
Statements that change data definition ALTER TABLE, CREATE TABLE, DROP TABLE, CREATE VIEW, DROP VIEW, CREATE INDEX, DROP INDEX, CREATE TRIGGER, DROP TRIGGER
Statements that change data INSERT, UPDATE, DELETE, REPLACE, TRUNCATE, SET
Statements that retrieve data SELECT, VALUES, PRAGMA, EXPLAIN
Statements for transactions START TRANSACTION, COMMIT, SAVEPOINT, RELEASE SAVEPOINT, ROLLBACK
Functions For example CAST(…), LENGTH(…), VERSION()

Statements that change data definition

ALTER TABLE

Syntax:

  • ALTER TABLE table-name RENAME TO new-table-name;
  • ALTER TABLE table-name ADD COLUMN column-name column-definition;
  • ALTER TABLE table-name ADD CONSTRAINT constraint-name constraint-definition;
  • ALTER TABLE table-name DROP CONSTRAINT constraint-name;
  • ALTER TABLE table-name ENABLE|DISABLE CHECK CONSTRAINT constraint-name;


../../../_images/alter_table.svg


ALTER is used to change a table’s name or a table’s elements.

Примеры:

For renaming a table with ALTER ... RENAME, the old-table must exist, the new-table must not exist. Example:
-- renaming a table: ALTER TABLE t1 RENAME TO t2;

For adding a column with ADD COLUMN, the table must exist, the table must be empty, the column name must be unique within the table. Example with a STRING column that must start with X:

ALTER TABLE t1 ADD COLUMN s4 STRING CHECK (s4 LIKE 'X%');

ALTER TABLE ... ADD COLUMN support was added in version 2.7.1.

For adding a table constraint with ADD CONSTRAINT, the table must exist, the table must be empty, the constraint name must be unique within the table. Example with a foreign-key constraint definition:
ALTER TABLE t1 ADD CONSTRAINT fk_s1_t1_1 FOREIGN KEY (s1) REFERENCES t1;

It is not possible to say CREATE TABLE table_a ... REFERENCES table_b ... if table b does not exist yet. This is a situation where ALTER TABLE is handy – users can CREATE TABLE table_a without the foreign key, then CREATE TABLE table_b, then ALTER TABLE table_a ... REFERENCES table_b ....

-- adding a primary-key constraint definition:
-- This is unusual because primary keys are created automatically
-- and it is illegal to have two primary keys for the same table.
-- However, it is possible to drop a primary-key index, and this
-- is a way to restore the primary key if that happens.
ALTER TABLE t1 ADD CONSTRAINT "pk_unnamed_T1_1" PRIMARY KEY (s1);

-- adding a unique-constraint definition:
-- Alternatively, you can say CREATE UNIQUE INDEX unique_key ON t1 (s1);
ALTER TABLE t1 ADD CONSTRAINT "unique_unnamed_T1_2" UNIQUE (s1);

-- Adding a check-constraint definition:
ALTER TABLE t1 ADD CONSTRAINT "ck_unnamed_T1_1" CHECK (s1 > 0);

For ALTER ... DROP CONSTRAINT, it is only legal to drop a named constraint. (Tarantool generates the constraint names automatically if the user does not provide them.) Since version 2.4.1, it is possible to drop any of the named table constraints, namely, PRIMARY KEY, UNIQUE, FOREIGN KEY, and CHECK.

To remove a unique constraint, use either ALTER ... DROP CONSTRAINT or DROP INDEX, which will drop the constraint as well.

-- dropping a constraint:
ALTER TABLE t1 DROP CONSTRAINT "fk_unnamed_JJ2_1";

For ALTER ... ENABLE|DISABLE CHECK CONSTRAINT, it is only legal to enable or disable a named constraint, and Tarantool only looks for names of check constraints. By default a constraint is enabled. If a constraint is disabled, then the check will not be performed.

-- disabling and re-enabling a constraint:
ALTER TABLE t1 DISABLE CHECK CONSTRAINT c;
ALTER TABLE t1 ENABLE CHECK CONSTRAINT c;

Limitations:

  • It is not possible to drop a column.
  • It is not possible to modify NOT NULL constraints or column properties DEFAULT and data type. However, it is possible to modify them with Tarantool/NOSQL, for example by calling space_object:format() with a different is_nullable value.

CREATE TABLE

Syntax:

CREATE TABLE [IF NOT EXISTS] table-name (column-definition or table-constraint list) [WITH ENGINE = string];


../../../_images/create_table.svg


Create a new base table, usually called a «table».

Примечание

A table is a base table if it is created with CREATE TABLE and contains data in persistent storage.

A table is a viewed table, or just «view», if it is created with CREATE VIEW and gets its data from other views or from base tables.

The table-name must be an identifier which is valid according to the rules for identifiers, and must not be the name of an already existing base table or view.

The column-definition or table-constraint list is a comma-separated list of column definitions or table constraint definitions. Column definitions and table constraint definitions are sometimes called table elements.

Rules:

  • A primary key is necessary; it can be specified with a table constraint PRIMARY KEY.
  • There must be at least one column.
  • When IF NOT EXISTS is specified, and there is already a table with the same name, the statement is ignored.
  • When WITH ENGINE = string is specified, where string must be either „memtx“ or „vinyl“, the table is created with that storage engine. When this clause is not specified, the table is created with the default engine, which is ordinarily „memtx“ but may be changed by updating the box.space._session_settings system table..

Actions:

  1. Tarantool evaluates each column definition and table-constraint, and returns an error if any of the rules is violated.
  2. Tarantool makes a new definition in the schema.
  3. Tarantool makes new indexes for PRIMARY KEY or UNIQUE constraints. A unique index name is created automatically.
  4. Usually Tarantool effectively executes a COMMIT statement.

Примеры:

-- the simplest form, with one column and one constraint:
CREATE TABLE t1 (s1 INTEGER, PRIMARY KEY (s1));

-- you can see the effect of the statement by querying
-- Tarantool system spaces:
SELECT * FROM "_space" WHERE "name" = 'T1';
SELECT * FROM "_index" JOIN "_space" ON "_index"."id" = "_space"."id"
         WHERE "_space"."name" = 'T1';

-- variation of the simplest form, with delimited identifiers
-- and a bracketed comment:
CREATE TABLE "T1" ("S1" INT /* synonym of INTEGER */, PRIMARY KEY ("S1"));

-- two columns, one named constraint
CREATE TABLE t1 (s1 INTEGER, s2 STRING, CONSTRAINT pk_s1s2_t1_1 PRIMARY KEY (s1, s2));

Limitations:

Column definition

Syntax:

column-name data-type [, column-constraint]

Define a column, which is a table element used in a CREATE TABLE statement.

The column-name must be an identifier which is valid according to the rules for identifiers.

Each column-name must be unique within a table.

Column definition – data type
../../../_images/data_type.svg


Every column has a data type: ANY or ARRAY or BOOLEAN or DECIMAL or DOUBLE or INTEGER or MAP or NUMBER or SCALAR or STRING or UNSIGNED or UUID or VARBINARY. The detailed description of data types is in the section Operands.

Column definition – the rules for the SCALAR data type

The rules for the SCALAR data type were significantly changed in Tarantool version v. 2.10.0.

SCALAR is a «complex» data type, unlike all the other data types which are «primitive». Two column values in a SCALAR column can have two different primitive data types.

  1. Any item defined as SCALAR has an underlying primitive type. For example, here:

    CREATE TABLE t (s1 SCALAR PRIMARY KEY);
INSERT INTO t VALUES (55), ('41');

    the underlying primitive type of the item in the first row is INTEGER because literal 55 has data type INTEGER, and the underlying primitive type in the second row is STRING (the data type of a literal is always clear from its format).

    Примитивный тип элемента гораздо менее важен, чем его установленный тип. Tarantool может определить примитивный тип по тому, как MsgPack хранит его, но это уже детали реализации.

  2. A SCALAR definition may not include a maximum length, as there is no suggested restriction.

  3. A SCALAR definition may include a COLLATE clause, which affects any items whose primitive data type is STRING. The default collation is «binary».

  4. Некоторые присваивания недопустимы, когда типы данных различаются, но разрешены, если речь об элементе типа SCALAR. Например, инструкция UPDATE ... SET column1 = 'a' выдаст ошибку, если столбец column1 определен как INTEGER. Однако она может быть выполнена, если column1 определен как SCALAR, при этом все значения типа INTEGER будут приведены к типу данных SCALAR.

  5. There is no literal syntax which implies data type SCALAR.

  6. Результат TYPEOF(x) — всегда 'scalar' или 'NULL', а не базовый тип данных. Не существует функции, которая гарантированно возвращает базовый тип данных. Например, TYPEOF(CAST(1 AS SCALAR)); возвращает 'scalar', а не 'integer'.

  7. Любая операция, которая требует неявного приведения элемента, определенного как SCALAR, завершится ошибкой во время выполнения. Например, если определение имеет вид:

    CREATE TABLE t (s1 SCALAR PRIMARY KEY, s2 INTEGER);

    и единственная строка в таблице T содержит значение s1 = 1, то есть примитивный тип этого значения — INTEGER, то операция UPDATE t SET s2 = s1; все равно не разрешена.

  8. For any dyadic operation that requires implicit casting for comparison, the syntax is legal and the operation will not fail at runtime. Take this situation: comparison with a primitive type VARBINARY and a primitive type STRING.

    CREATE TABLE t (s1 SCALAR PRIMARY KEY);
INSERT INTO t VALUES (X'41');
SELECT * FROM t WHERE s1 > 'a';

    Такое сравнение корректно, поскольку Tarantool знает, в каком порядке стоят значения X'41' и 'a' типа 'scalar' в Tarantool/NoSQL. В этом случае примитивный тип имеет значение.

  9. Результат операции min/max над столбцом, определенным как SCALAR, тоже будет иметь тип SCALAR. Пользователям необходимо заранее знать примитивный тип результата. Пример:

    CREATE TABLE t (s1 INTEGER, s2 SCALAR PRIMARY KEY);
INSERT INTO t VALUES (1, X'44'), (2, 11), (3, 1E4), (4, 'a');
SELECT cast(min(s2) AS INTEGER), hex(cast(max(s2) as VARBINARY)) FROM t;

    The result is: - - [11, '44',]

    Это возможно только с правилами Tarantool/NoSQL для типа scalar. Однако вызов SELECT SUM(s2) не будет допустим: суммирование в этом случае потребует неявного приведения VARBINARY к числовому значению, что неразумно.

  10. The result data type of a primitive combination is sometimes SCALAR although Tarantool in effect uses the primitive data type not the defined data type. (Here the word «combination» is used in the way that the standard document uses it for section «Result of data type combinations».) Therefore for greatest(1E308, 'a', 0, X'00') the result is X’00“ but typeof(greatest(1E308, 'a', 0, X'00') is „scalar“.

  11. Объединение двух значений типа SCALAR иногда представляется примитивным типом. Например, SELECT TYPEOF((SELECT CAST('a' AS SCALAR) UNION SELECT CAST('a' AS SCALAR))); вернет 'string'.

Column definition – relation to NoSQL

All of the SQL data types except SCALAR correspond to Tarantool/NoSQL types with the same name. For example an SQL STRING is stored in a NoSQL space as type = „string“.

Therefore specifying an SQL data type X determines that the storage will be in a space with a format column saying that the NoSQL type is „x“.

The rules for that NoSQL type are applicable to the SQL data type.

If two items have SQL data types that have the same underlying type, then they are compatible for all assignment or comparison purposes.

If two items have SQL data types that have different underlying types, then the rules for explicit casts, or implicit (assignment) casts, or implicit (comparison) casts, apply.

Существует одно значение с плавающей точкой, которое не обрабатывается SQL: -NaN воспринимается как NULL, хотя его тип данных — 'double'.

Before Tarantool v. 2.10.0, there were also some Tarantool/NoSQL data types which had no corresponding SQL data types. For example, SELECT "flags" FROM "_vspace"; would return a column whose SQL data type is VARBINARY rather than MAP. Such columns can only be manipulated in SQL by invoking Lua functions.

Column definition – column-constraint or default clause
../../../_images/column_constraint.svg

The column-constraint or default clause may be as follows:

Тип Comment
NOT NULL means «it is illegal to assign a NULL to this column»
PRIMARY KEY explained in the Table constraint definition section
UNIQUE explained in the Table constraint definition section
CHECK (expression) explained in the Table constraint definition section
foreign-key-clause explained in the Table constraint definition for foreign keys section
DEFAULT expression means «if INSERT does not assign to this column then assign expression result to this column» – if there is no DEFAULT clause then DEFAULT NULL is assumed

If column-constraint is PRIMARY KEY, this is a shorthand for a separate table-constraint definition: «PRIMARY KEY (column-name)».

If column-constraint is UNIQUE, this is a shorthand for a separate table-constraint definition: «UNIQUE (column-name)».

If column-constraint is CHECK, this is a shorthand for a separate table-constraint definition: «CHECK (expression)».

Columns defined with PRIMARY KEY are automatically NOT NULL.

To enforce some restrictions that Tarantool does not enforce automatically, add CHECK clauses, like these:

CREATE TABLE t ("smallint" INTEGER PRIMARY KEY CHECK ("smallint" <= 32767 AND "smallint" >= -32768));
CREATE TABLE t ("shorttext" STRING PRIMARY KEY CHECK (length("shorttext") <= 10));

but this may cause inserts or updates to be slow.

Column definition – examples

These are shown within CREATE TABLE statements. Data types may also appear in CAST functions.

-- the simple form with column-name and data-type
CREATE TABLE t (column1 INTEGER ...);
-- with column-name and data-type and column-constraint
CREATE TABLE t (column1 STRING PRIMARY KEY ...);
-- with column-name and data-type and collate-clause
CREATE TABLE t (column1 SCALAR COLLATE "unicode" ...);

-- with all possible data types and aliases
CREATE TABLE t
(column1 BOOLEAN, column2 BOOL,
 column3 INT PRIMARY KEY, column4 INTEGER,
 column5 DOUBLE,
 column6 NUMBER,
 column7 STRING, column8 STRING COLLATE "unicode",
 column9 TEXT, columna TEXT COLLATE "unicode_sv_s1",
 columnb VARCHAR(0), columnc VARCHAR(100000) COLLATE "binary",
 columnd UUID,
 columne VARBINARY,
 columnf SCALAR, columng SCALAR COLLATE "unicode_uk_s2",
 columnh DECIMAL,
 columni ARRAY,
 columnj MAP,
 columnk ANY);

-- with all possible column constraints and a default clause
CREATE TABLE t
(column1 INTEGER NOT NULL,
 column2 INTEGER PRIMARY KEY,
 column3 INTEGER UNIQUE,
 column4 INTEGER CHECK (column3 > column2),
 column5 INTEGER REFERENCES t,
 column6 INTEGER DEFAULT NULL);

Table constraint definition

A table constraint restricts the data you can add to the table. If you try to insert invalid data on a column, Tarantool throws an error.

A table constraint has the following syntax:

[CONSTRAINT [name]] constraint_expression

constraint_expression:
  | PRIMARY KEY (column_name, ...)
  | UNIQUE (column_name, ...)
  | CHECK (expression)
  | FOREIGN KEY (column_name, ...) foreign_key_clause

Define a constraint, which is a table element used in a CREATE TABLE statement.

A constraint name must be an identifier that is valid according to the rules for identifiers. A constraint name must be unique within the table for a specific constraint type. For example, the CHECK and FOREIGN KEY constraints can have the same name.

PRIMARY KEY constraints

PRIMARY KEY constraints look like this:

PRIMARY KEY (column_name, ...)

There is a shorthand: specifying PRIMARY KEY in a column definition.

  • Every table must have one and only one primary key.
  • Primary-key columns are automatically NOT NULL.
  • Primary-key columns are automatically indexed.
  • Primary-key columns are unique. That means it is illegal to have two rows with the same values for the columns specified in the constraint.

Example 1: one-column primary key

  1. Create an author table with the id primary key column:

    CREATE TABLE author (
    id INTEGER PRIMARY KEY,
    name STRING NOT NULL
);

    Insert data into this table:

    INSERT INTO author VALUES (1, 'Leo Tolstoy'),
                          (2, 'Fyodor Dostoevsky');

  2. On an attempt to add an author with the existing id, the following error is raised:

    INSERT INTO author VALUES (2, 'Alexander Pushkin');
/*
- Duplicate key exists in unique index "pk_unnamed_author_1" in space "author" with
  old tuple - [2, "Fyodor Dostoevsky"] and new tuple - [2, "Alexander Pushkin"]
*/

Example 2: two-column primary key

  1. Create a book table with the primary key defined on two columns:

    CREATE TABLE book (
    id INTEGER,
    title STRING NOT NULL,
    PRIMARY KEY (id, title)
);

    Insert data into this table:

    INSERT INTO book VALUES (1, 'War and Peace'),
                        (2, 'Crime and Punishment');

  2. On an attempt to add the existing book, the following error is raised:

    INSERT INTO book VALUES (2, 'Crime and Punishment');
/*
- Duplicate key exists in unique index "pk_unnamed_book_1" in space "BOOK" with old
  tuple - [2, "Crime and Punishment"] and new tuple - [2, "Crime and Punishment"]
*/

PRIMARY KEY with the AUTOINCREMENT modifier may be specified in one of two ways:

  • In a column definition after the words PRIMARY KEY, as in CREATE TABLE t (c INTEGER PRIMARY KEY AUTOINCREMENT);
  • In a PRIMARY KEY (column-list) after a column name, as in CREATE TABLE t (c INTEGER, PRIMARY KEY (c AUTOINCREMENT));

When AUTOINCREMENT is specified, the column must be a primary-key column and it must be INTEGER or UNSIGNED.

Only one column in the table may be autoincrement. However, it is legal to say PRIMARY KEY (a, b, c AUTOINCREMENT) – in that case, there are three columns in the primary key but only the third column (c) is AUTOINCREMENT.

As the name suggests, values in an autoincrement column are automatically incremented. That is: if a user inserts NULL in the column, then the stored value will be the smallest non-negative integer that has not already been used. This occurs because autoincrement columns are associated with sequences.

UNIQUE constraints

UNIQUE constraints look like this:

UNIQUE (column_name, ...)

There is a shorthand: specifying UNIQUE in a column definition.

Unique constraints are similar to primary-key constraints, except that:

  • A table may have any number of unique keys, and unique keys are not automatically NOT NULL.
  • Unique columns are automatically indexed.
  • Unique columns are unique. That means it is illegal to have two rows with the same values in the unique-key columns.

Example 1: one-column unique constraint

  1. Create an author table with the unique name column:

    CREATE TABLE author (
    id INTEGER PRIMARY KEY,
    name STRING UNIQUE
);

    Insert data into this table:

    INSERT INTO author VALUES (1, 'Leo Tolstoy'),
                          (2, 'Fyodor Dostoevsky');

  2. On an attempt to add an author with the same name, the following error is raised:

    INSERT INTO author VALUES (3, 'Leo Tolstoy');
/*
- Duplicate key exists in unique index "unique_unnamed_author_2" in space "author"
  with old tuple - [1, "Leo Tolstoy"] and new tuple - [3, "Leo Tolstoy"]
*/

Example 2: two-column unique constraint

  1. Create a book table with the unique constraint defined on two columns:

    CREATE TABLE book (
    id INTEGER PRIMARY KEY,
    title STRING NOT NULL,
    author_id INTEGER UNIQUE,
    UNIQUE (title, author_id)
);

    Insert data into this table:

    INSERT INTO book VALUES (1, 'War and Peace', 1),
                        (2, 'Crime and Punishment', 2);

  2. On an attempt to add a book with duplicated values, the following error is raised:

    INSERT INTO book VALUES (3, 'War and Peace', 1);
/*
- Duplicate key exists in unique index "unique_unnamed_book_2" in space "book" with
  old tuple - [1, "War and Peace", 1] and new tuple - [3, "War and Peace", 1]
*/

CHECK constraints

The CHECK constraint is used to limit the value range that a column can store. CHECK constraints look like this:

CHECK (expression)

There is a shorthand: specifying CHECK in a column definition.

The expression may be anything that returns a BOOLEAN result = TRUE or FALSE or UNKNOWN.
The expression may not contain a subquery.
If the expression contains a column name, the column must exist in the table.
If a CHECK constraint is specified, the table must not contain rows where the expression is FALSE. (The table may contain rows where the expression is either TRUE or UNKNOWN.)
Constraint checking may be stopped with ALTER TABLE … DISABLE CHECK CONSTRAINT and restarted with ALTER TABLE … ENABLE CHECK CONSTRAINT.

Example

  1. Create an author table with the name column that should contain values longer than 4 characters:

    CREATE TABLE author (
    id INTEGER PRIMARY KEY,
    name STRING,
    CONSTRAINT check_name_length CHECK (CHAR_LENGTH(name) > 4)
);

    Insert data into this table:

    INSERT INTO author VALUES (1, 'Leo Tolstoy'),
                          (2, 'Fyodor Dostoevsky');

  2. On an attempt to add an author with a name shorter than 5 characters, the following error is raised:

    INSERT INTO author VALUES (3, 'Alex');
/*
- Check constraint 'check_name_length' failed for a tuple
*/

Table constraint definition for foreign keys

A foreign key is a constraint that can be used to enforce data integrity across related tables. A foreign key constraint is defined on the child table that references the parent table’s column values.

Foreign key constraints look like this:

FOREIGN KEY (referencing_column_name, ...)
    REFERENCES referenced_table_name (referenced_column_name, ...)

You can also add a reference in a column definition:

referencing_column_name column_definition
    REFERENCES referenced_table_name(referenced_column_name)

Примечание

Since 2.11.0, the following referencing options aren’t supported anymore:

  • The ON UPDATE and ON DELETE triggers. The RESTRICT trigger action is used implicitly.
  • The MATCH subclause. MATCH FULL is used implicitly.
  • DEFERRABLE constraints. The INITIALLY IMMEDIATE constraint check time rule is used implicitly.

Note that a referenced column should meet one of the following requirements:

  • A referenced column is a PRIMARY KEY column.
  • A referenced column has a UNIQUE constraint.
  • A referenced column has a UNIQUE index.

Note that before the 2.11.0 version, an index existence for the referenced columns is checked when creating a constraint (for example, using CREATE TABLE or ALTER TABLE). Starting with 2.11.0, this check is weakened and the existence of an index is checked during data insertion.

Example

This example shows how to create a relation between the parent and child tables through a single-column foreign key:

  1. First, create a parent author table:

    CREATE TABLE author (
    id INTEGER PRIMARY KEY,
    name STRING NOT NULL
);

    Insert data into this table:

    INSERT INTO author VALUES (1, 'Leo Tolstoy'),
                          (2, 'Fyodor Dostoevsky');

  2. Create a child book table whose author_id column references the id column from the author table:

    CREATE TABLE book (
    id INTEGER PRIMARY KEY,
    title STRING NOT NULL,
    author_id INTEGER NOT NULL UNIQUE,
    FOREIGN KEY (author_id)
        REFERENCES author (id)
);

    Alternatively, you can add a reference in a column definition:

    CREATE TABLE book (
    id INTEGER PRIMARY KEY,
    title STRING NOT NULL,
    author_id INTEGER NOT NULL UNIQUE REFERENCES author(id)
);

    Insert data to the book table:

    INSERT INTO book VALUES (1, 'War and Peace', 1),
                        (2, 'Crime and Punishment', 2);

  3. Check how the created foreign key constraint enforces data integrity. The following error is raised on an attempt to insert a new book with the author_id value that doesn’t exist in the parent author table:

    INSERT INTO book VALUES (3, 'Eugene Onegin', 3);
/*
- 'Foreign key constraint ''fk_unnamed_book_1'' failed: foreign tuple was not found'
*/

    On an attempt to delete an author that already has books in the book table, the following error is raised:

    DELETE FROM author WHERE id = 2;
/*
- 'Foreign key ''fk_unnamed_book_1'' integrity check failed: tuple is referenced'
*/

DROP TABLE

Syntax:

DROP TABLE [IF EXISTS] table-name;


../../../_images/drop_table.svg


Drop a table.

The table-name must identify a table that was created earlier with the CREATE TABLE statement.

Rules:

  • If there is a view that references the table, the drop will fail. Please drop the referencing view with DROP VIEW first.
  • If there is a foreign key that references the table, the drop will fail. Please drop the referencing constraint with ALTER TABLE … DROP first.

Actions:

  1. Tarantool returns an error if the table does not exist and there is no IF EXISTS clause.
  2. The table and all its data are dropped.
  3. All indexes for the table are dropped.
  4. All triggers for the table are dropped.
  5. Usually Tarantool effectively executes a COMMIT statement.

Примеры:

-- the simple case:
DROP TABLE t31;
-- with an IF EXISTS clause:
DROP TABLE IF EXISTS t31;

See also: DROP VIEW.

CREATE VIEW

Syntax:

CREATE VIEW [IF NOT EXISTS] view-name [(column-list)] AS subquery;


../../../_images/create_view.svg


Create a new viewed table, usually called a «view».

The view-name must be valid according to the rules for identifiers.

The optional column-list must be a comma-separated list of names of columns in the view.

The syntax of the subquery must be the same as the syntax of a SELECT statement, or of a VALUES clause.

Rules:

  • There must not already be a base table or view with the same name as view-name.
  • If column-list is specified, the number of columns in column-list must be the same as the number of columns in the select list of the subquery.

Actions:

  1. Tarantool will throw an error if a rule is violated.
  2. Tarantool will create a new persistent object with column-names equal to the names in the column-list or the names in the subquery’s select list.
  3. Usually Tarantool effectively executes a COMMIT statement.

Примеры:

-- the simple case:
CREATE VIEW v AS SELECT column1, column2 FROM t;
-- with a column-list:
CREATE VIEW v (a,b) AS SELECT column1, column2 FROM t;

Limitations:

  • It is not possible to insert or update or delete from a view, although sometimes a possible substitution is to create an INSTEAD OF trigger.

DROP VIEW

Syntax:

DROP VIEW [IF EXISTS] view-name;


../../../_images/drop_view.svg


Drop a view.

The view-name must identify a view that was created earlier with the CREATE VIEW statement.

Rules: none

Actions:

  1. Tarantool returns an error if the view does not exist and there is no IF EXISTS clause.
  2. The view is dropped.
  3. All triggers for the view are dropped.
  4. Usually Tarantool effectively executes a COMMIT statement.

Примеры:

-- the simple case:
DROP VIEW v31;
-- with an IF EXISTS clause:
DROP VIEW IF EXISTS v31;

See also: DROP TABLE.

CREATE INDEX

Syntax:

CREATE [UNIQUE] INDEX [IF NOT EXISTS] index-name ON table-name (column-list);


../../../_images/create_index.svg


Create an index.

The index-name must be valid according to the rules for identifiers.

The table-name must refer to an existing table.

The column-list must be a comma-separated list of names of columns in the table.

Rules:

  • There must not already be, for the same table, an index with the same name as index-name. But there may already be, for a different table, an index with the same name as index-name.
  • The maximum number of indexes per table is 128.

Actions:

  1. Tarantool will throw an error if a rule is violated.
  2. If the new index is UNIQUE, Tarantool will throw an error if any row exists with columns that have duplicate values.
  3. Tarantool will create a new index.
  4. Usually Tarantool effectively executes a COMMIT statement.

Automatic indexes:

Indexes may be created automatically for columns mentioned in the PRIMARY KEY or UNIQUE clauses of a CREATE TABLE statement. If an index was created automatically, then the index-name has four parts:

  1. pk if this is for a PRIMARY KEY clause, unique if this is for a UNIQUE clause;
  2. _unnamed_;
  3. the name of the table;
  4. _ and an ordinal number; the first index is 1, the second index is 2, and so on.

For example, after CREATE TABLE t (s1 INTEGER PRIMARY KEY, s2 INTEGER, UNIQUE (s2)); there are two indexes named pk_unnamed_T_1 and unique_unnamed_T_2. You can confirm this by saying SELECT * FROM "_index"; which will list all indexes on all tables. There is no need to say CREATE INDEX for columns that already have automatic indexes.

Примеры:

-- the simple case
CREATE INDEX idx_column1_t_1 ON t (column1);
-- with IF NOT EXISTS clause
CREATE INDEX IF NOT EXISTS idx_column1_t_1 ON t (column1);
-- with UNIQUE specifier and more than one column
CREATE UNIQUE INDEX idx_unnamed_t_1 ON t (column1, column2);

Dropping an automatic index created for a unique constraint will drop the unique constraint as well.

DROP INDEX

Syntax:

DROP INDEX [IF EXISTS] index-name ON table-name;


../../../_images/drop_index.svg


The index-name must be the name of an existing index, which was created with CREATE INDEX. Or, the index-name must be the name of an index that was created automatically due to a PRIMARY KEY or UNIQUE clause in the CREATE TABLE statement. To see what a table’s indexes are, use PRAGMA index_list(table-name);.

Rules: none

Actions:

  1. Tarantool throws an error if the index does not exist, or is an automatically created index.
  2. Tarantool will drop the index.
  3. Usually Tarantool effectively executes a COMMIT statement.

Пример:

-- the simplest form:
DROP INDEX idx_unnamed_t_1 ON t;

CREATE TRIGGER

Syntax:

CREATE TRIGGER [IF NOT EXISTS] trigger-name
BEFORE|AFTER|INSTEAD OF
DELETE|INSERT|UPDATE ON table-name
FOR EACH ROW
[WHEN search-condition]
BEGIN
delete-statement | insert-statement | replace-statement | select-statement | update-statement;
[delete-statement | insert-statement | replace-statement | select-statement | update-statement; ...]
END;


../../../_images/create_trigger.svg


The trigger-name must be valid according to the rules for identifiers.

If the trigger action time is BEFORE or AFTER, then the table-name must refer to an existing base table.

If the trigger action time is INSTEAD OF, then the table-name must refer to an existing view.

Rules:

  • There must not already be a trigger with the same name as trigger-name.
  • Triggers on different tables or views share the same namespace.
  • The statements between BEGIN and END should not refer to the table-name mentioned in the ON clause.
  • The statements between BEGIN and END should not contain an INDEXED BY clause.

SQL triggers are not activated by Tarantool/NoSQL requests. This will change in a future version.

On a replica, effects of trigger execution are applied, and the SQL triggers themselves are not activated upon replication events.

NoSQL triggers are activated both on replica and master, thus if you have a NoSQL trigger on a replica, it is activated when applying effects of an SQL trigger.

Actions:

  1. Tarantool will throw an error if a rule is violated.
  2. Tarantool will create a new trigger.
  3. Usually Tarantool effectively executes a COMMIT statement.

Примеры:

-- the simple case:
CREATE TRIGGER stores_before_insert BEFORE INSERT ON stores FOR EACH ROW
  BEGIN DELETE FROM warehouses; END;
-- with IF NOT EXISTS clause:
CREATE TRIGGER IF NOT EXISTS stores_before_insert BEFORE INSERT ON stores FOR EACH ROW
  BEGIN DELETE FROM warehouses; END;
-- with FOR EACH ROW and WHEN clauses:
CREATE TRIGGER stores_before_insert BEFORE INSERT ON stores FOR EACH ROW WHEN a=5
  BEGIN DELETE FROM warehouses; END;
-- with multiple statements between BEGIN and END:
CREATE TRIGGER stores_before_insert BEFORE INSERT ON stores FOR EACH ROW
  BEGIN DELETE FROM warehouses; INSERT INTO inventories VALUES (1); END;

Trigger extra clauses

  • UPDATE OF column-list

    After BEFORE|AFTER UPDATE it is optional to add OF column-list. If any of the columns in column-list is affected at the time the row is processed, then the trigger will be activated for that row. For example:

    CREATE TRIGGER table1_before_update
 BEFORE UPDATE  OF column1, column2 ON table1
 FOR EACH ROW
 BEGIN UPDATE table2 SET column1 = column1 + 1; END;
UPDATE table1 SET column3 = column3 + 1; -- Trigger will not be activated
UPDATE table1 SET column2 = column2 + 0; -- Trigger will be activated

  • WHEN

    After table-name FOR EACH ROW it is optional to add [WHEN expression]. If the expression is true at the time the row is processed, only then will the trigger will be activated for that row. For example:

    CREATE TRIGGER table1_before_update BEFORE UPDATE ON table1 FOR EACH ROW
 WHEN (SELECT COUNT(*) FROM table1) > 1
 BEGIN UPDATE table2 SET column1 = column1 + 1; END;

    This trigger will not be activated unless there is more than one row in table1.

  • OLD and NEW

    The keywords OLD and NEW have special meaning in the context of trigger action:

    • OLD.column-name refers to the value of column-name before the change.
    • NEW.column-name refers to the value of column-name after the change.

    Пример:

    CREATE TABLE table1 (column1 STRING, column2 INTEGER PRIMARY KEY);
CREATE TABLE table2 (column1 STRING, column2 STRING, column3 INTEGER PRIMARY KEY);
INSERT INTO table1 VALUES ('old value', 1);
INSERT INTO table2 VALUES ('', '', 1);
CREATE TRIGGER table1_before_update BEFORE UPDATE ON table1 FOR EACH ROW
 BEGIN UPDATE table2 SET column1 = old.column1, column2 = new.column1; END;
UPDATE table1 SET column1 = 'new value';
SELECT * FROM table2;

    At the beginning of the UPDATE for the single row of table1, the value in column1 is „old value“ – so that is what is seen as old.column1.

    At the end of the UPDATE for the single row of table1, the value in column1 is „new value“ – so that is what is seen as new.column1. (OLD and NEW are qualifiers for table1, not table2.)

    Therefore, SELECT * FROM table2; returns ['old value', 'new value'].

    OLD.column-name does not exist for an INSERT trigger.

    NEW.column-name does not exist for a DELETE trigger.

    OLD and NEW are read-only; you cannot change their values.

  • Deprecated or illegal statements:

    It is illegal for the trigger action to include a qualified column reference other than OLD.column-name or NEW.column-name. For example, CREATE TRIGGER ... BEGIN UPDATE table1 SET table1.column1 = 5; END; is illegal.

    It is illegal for the trigger action to include statements that include a WITH clause, a DEFAULT VALUES clause, or an INDEXED BY clause.

    It is usually not a good idea to have a trigger on table1 which causes a change on table2, and at the same time have a trigger on table2 which causes a change on table1. For example:

    CREATE TRIGGER table1_before_update
 BEFORE UPDATE ON table1
 FOR EACH ROW
 BEGIN UPDATE table2 SET column1 = column1 + 1; END;
CREATE TRIGGER table2_before_update
 BEFORE UPDATE ON table2
 FOR EACH ROW
 BEGIN UPDATE table1 SET column1 = column1 + 1; END;

    Luckily UPDATE table1 ... will not cause an infinite loop, because Tarantool recognizes when it has already updated so it will stop. However, not every DBMS acts this way.

Trigger activation

These are remarks concerning trigger activation.

Standard terminology:

  • «trigger action time» = BEFORE or AFTER or INSTEAD OF
  • «trigger event» = INSERT or DELETE or UPDATE
  • «triggered statement» = BEGIN … DELETE|INSERT|REPLACE|SELECT|UPDATE … END
  • «triggered when clause» = WHEN search-condition
  • «activate» = execute a triggered statement
  • some vendors use the word «fire» instead of «activate»

If there is more than one trigger for the same trigger event, Tarantool may execute the triggers in any order.

It is possible for a triggered statement to cause activation of another triggered statement. For example, this is legal:

CREATE TRIGGER t1_before_delete BEFORE DELETE ON t1 FOR EACH ROW BEGIN DELETE FROM t2; END;
CREATE TRIGGER t2_before_delete BEFORE DELETE ON t2 FOR EACH ROW BEGIN DELETE FROM t3; END;

Activation occurs FOR EACH ROW, not FOR EACH STATEMENT. Therefore, if no rows are candidates for insert or update or delete, then no triggers are activated.

The BEFORE trigger is activated even if the trigger event fails.

If an UPDATE trigger event does not make a change, the trigger is activated anyway. For example, if row 1 column1 contains 'a', and the trigger event is UPDATE ... SET column1 = 'a';, the trigger is activated.

The triggered statement may refer to a function: RAISE(FAIL, error-message). If a triggered statement invokes a RAISE(FAIL, error-message) function, or if a triggered statement causes an error, then statement execution stops immediately.

The triggered statement may refer to column values within the rows being changed. in this case:

  • The row «as of before» the change is called the «old» row (which makes sense only for UPDATE and DELETE statements).
  • The row «as of after» the change is called the «new» row (which makes sense only for UPDATE and INSERT statements).

This example shows how an INSERT can be done to a view by referring to the «new» row:

CREATE TABLE t (s1 INTEGER PRIMARY KEY, s2 INTEGER);
CREATE VIEW v AS SELECT s1, s2 FROM t;
CREATE TRIGGER v_instead_of INSTEAD OF INSERT ON v
  FOR EACH ROW
  BEGIN INSERT INTO t VALUES (new.s1, new.s2); END;
INSERT INTO v VALUES (1, 2);

Ordinarily saying INSERT INTO view_name ... is illegal in Tarantool, so this is a workaround.

It is possible to generalize this so that all data-change statements on views will change the base tables, provided that the view contains all the columns of the base table, and provided that the triggers refer to those columns when necessary, as in this example:

CREATE TABLE base_table (primary_key_column INTEGER PRIMARY KEY, value_column INTEGER);
CREATE VIEW viewed_table AS SELECT primary_key_column, value_column FROM base_table;
CREATE TRIGGER viewed_table_instead_of_insert INSTEAD OF INSERT ON viewed_table FOR EACH ROW
  BEGIN
    INSERT INTO base_table VALUES (new.primary_key_column, new.value_column); END;
CREATE TRIGGER viewed_table_instead_of_update INSTEAD OF UPDATE ON viewed_table FOR EACH ROW
  BEGIN
    UPDATE base_table
    SET primary_key_column = new.primary_key_column, value_column = new.value_column
    WHERE primary_key_column = old.primary_key_column; END;
CREATE TRIGGER viewed_table_instead_of_delete INSTEAD OF DELETE ON viewed_table FOR EACH ROW
  BEGIN
    DELETE FROM base_table WHERE primary_key_column = old.primary_key_column; END;

When INSERT or UPDATE or DELETE occurs for table X, Tarantool usually operates in this order (a basic scheme):

For each row
  Perform constraint checks
  For each BEFORE trigger that refers to table X
    Check that the trigger's WHEN condition is true.
    Execute what is in the triggered statement.
  Insert or update or delete the row in table X.
  Perform more constraint checks
  For each AFTER trigger that refers to table X
    Check that the trigger's WHEN condition is true.
    Execute what is in the triggered statement.

However, Tarantool does not guarantee execution order when there are multiple constraints, or multiple triggers for the same event (including NoSQL on_replace triggers or SQL INSTEAD OF triggers that affect a view of table X).

The maximum number of trigger activations per statement is 32.

INSTEAD OF triggers

A trigger which is created with the clause
INSTEAD OF INSERT|UPDATE|DELETE ON view-name
is an INSTEAD OF trigger. For each affected row, the trigger action is performed «instead of» the INSERT or UPDATE or DELETE statement that causes trigger activation.

For example, ordinarily it is illegal to INSERT rows in a view, but it is legal to create a trigger which intercepts attempts to INSERT, and puts rows in the underlying base table:

CREATE TABLE t1 (column1 INTEGER PRIMARY KEY, column2 INTEGER);
CREATE VIEW v1 AS SELECT column1, column2 FROM t1;
CREATE TRIGGER v1_instead_of INSTEAD OF INSERT ON v1 FOR EACH ROW BEGIN
 INSERT INTO t1 VALUES (NEW.column1, NEW.column2); END;
INSERT INTO v1 VALUES (1, 1);
-- ... The result will be: table t1 will contain a new row.

INSTEAD OF triggers are only legal for views, while BEFORE or AFTER triggers are only legal for base tables.

It is legal to create INSTEAD OF triggers with triggered WHEN clauses.

Limitations:

  • It is legal to create INSTEAD OF triggers with UPDATE OF column-list clauses, but they are not standard SQL.

Пример:

CREATE TRIGGER ev1_instead_of_update
  INSTEAD OF UPDATE OF column2,column1 ON ev1
  FOR EACH ROW BEGIN
  INSERT INTO et2 VALUES (NEW.column1, NEW.column2); END;

DROP TRIGGER

Syntax:

DROP TRIGGER [IF EXISTS] trigger-name;


../../../_images/drop_trigger.svg


Drop a trigger.

The trigger-name must identify a trigger that was created earlier with the CREATE TRIGGER statement.

Rules: none

Actions:

  1. Tarantool returns an error if the trigger does not exist and there is no IF EXISTS clause.
  2. The trigger is dropped.
  3. Usually Tarantool effectively executes a COMMIT statement.

Примеры:

-- the simple case:
DROP TRIGGER table1_before_insert;
-- with an IF EXISTS clause:
DROP TRIGGER IF EXISTS table1_before_insert;

Statements that change data

INSERT

Syntax:

  • INSERT INTO table-name [(column-list)] VALUES (expression-list) [, (expression-list)];
  • INSERT INTO table-name [(column-list)]  select-statement;
  • INSERT INTO table-name DEFAULT VALUES;


../../../_images/insert.svg


Insert one or more new rows into a table.

The table-name must be a name of a table defined earlier with CREATE TABLE.

The optional column-list must be a comma-separated list of names of columns in the table.

The expression-list must be a comma-separated list of expressions; each expression may contain literals and operators and subqueries and function invocations.

Rules:

  • The values in the expression-list are evaluated from left to right.
  • The order of the values in the expression-list must correspond to the order of the columns in the table, or (if a column-list is specified) to the order of the columns in the column-list.
  • The data type of the value should correspond to the data type of the column, that is, the data type that was specified with CREATE TABLE.
  • If a column-list is not specified, then the number of expressions must be the same as the number of columns in the table.
  • If a column-list is specified, then some columns may be omitted; omitted columns will get default values.
  • The parenthesized expression-list may be repeated – (expression-list),(expression-list),... – for multiple rows.

Actions:

  1. Tarantool evaluates each expression in expression-list, and returns an error if any of the rules is violated.
  2. Tarantool creates zero or more new rows containing values based on the values in the VALUES list or based on the results of the select-expression or based on the default values.
  3. Tarantool executes constraint checks and trigger actions and the actual insertion.

Примеры:

-- the simplest form:
INSERT INTO table1 VALUES (1, 'A');
-- with a column list:
INSERT INTO table1 (column1, column2) VALUES (2, 'B');
-- with an arithmetic operator in the first expression:
INSERT INTO table1 VALUES (2 + 1, 'C');
-- put two rows in the table:
INSERT INTO table1 VALUES (4, 'D'), (5, 'E');

See also: REPLACE statement.

UPDATE

Syntax:

UPDATE table-name SET column-name = expression [, column-name = expression ...] [WHERE search-condition];


../../../_images/update.svg


Update zero or more existing rows in a table.

The table-name must be a name of a table defined earlier with CREATE TABLE or CREATE VIEW.

The column-name must be an updatable column in the table.

The expression may contain literals and operators and subqueries and function invocations and column names.

Rules:

  • The values in the SET clause are evaluated from left to right.
  • The data type of the value should correspond to the data type of the column, that is, the data type that was specified with CREATE TABLE.
  • If a search-condition is not specified, then all rows in the table will be updated; otherwise only those rows which match the search-condition will be updated.

Actions:

  1. Tarantool evaluates each expression in the SET clause, and returns an error if any of the rules is violated. For each row that is found by the WHERE clause, a temporary new row is formed based on the original contents and the modifications caused by the SET clause.
  2. Tarantool executes constraint checks and trigger actions and the actual update.

Примеры:

-- the simplest form:
UPDATE t SET column1 = 1;
-- with more than one assignment in the SET clause:
UPDATE t SET column1 = 1, column2 = 2;
-- with a WHERE clause:
UPDATE t SET column1 = 5 WHERE column2 = 6;

Special cases:

It is legal to say SET (list of columns) = (list of values). For example:

UPDATE t SET (column1, column2, column3) = (1, 2, 3);

It is not legal to assign to a column more than once. For example:

INSERT INTO t (column1) VALUES (0);
UPDATE t SET column1 = column1 + 1, column1 = column1 + 1;

The result is an error: «duplicate column name».

It is not legal to assign to a primary-key column.

DELETE

Syntax:

DELETE FROM table-name [WHERE search-condition];


../../../_images/delete.svg


Delete zero or more existing rows in a table.

The table-name must be a name of a table defined earlier with CREATE TABLE or CREATE VIEW.

The search-condition may contain literals and operators and subqueries and function invocations and column names.

Rules:

  • If a search-condition is not specified, then all rows in the table will be deleted; otherwise only those rows which match the search-condition will be deleted.

Actions:

  1. Tarantool evaluates each expression in the search-condition, and returns an error if any of the rules is violated.
  2. Tarantool finds the set of rows that are to be deleted.
  3. Tarantool executes constraint checks and trigger actions and the actual deletion.

Примеры:

-- the simplest form:
DELETE FROM t;
-- with a WHERE clause:
DELETE FROM t WHERE column2 = 6;

REPLACE

Syntax:

  • REPLACE INTO table-name [(column-list)] VALUES (expression-list) [, (expression-list)];
  • REPLACE INTO table-name [(column-list)] select-statement;
  • REPLACE INTO table-name DEFAULT VALUES;


../../../_images/replace.svg


Insert one or more new rows into a table, or update existing rows.

If a row already exists (as determined by the primary key or any unique key), then the action is delete + insert, and the rules are the same as for a DELETE statement followed by an INSERT statement. Otherwise the action is insert, and the rules are the same as for the INSERT statement.

Примеры:

-- the simplest form:
REPLACE INTO table1 VALUES (1, 'A');
-- with a column list:
REPLACE INTO table1 (column1, column2) VALUES (2, 'B');
-- with an arithmetic operator in the first expression:
REPLACE INTO table1 VALUES (2 + 1, 'C');
-- put two rows in the table:
REPLACE INTO table1 VALUES (4, 'D'), (5, 'E');

See also: INSERT Statement, UPDATE Statement.

TRUNCATE

Syntax:

TRUNCATE TABLE table-name;


../../../_images/truncate.svg


Remove all rows in the table.

TRUNCATE is considered to be a schema-change rather than a data-change statement, so it does not work within transactions (it cannot be rolled back).

Rules:

  • It is illegal to truncate a table which is referenced by a foreign key.
  • It is illegal to truncate a table which is also a system space, such as _space.
  • The table must be a base table rather than a view.

Actions:

  1. All rows in the table are removed. Usually this is faster than DELETE FROM table-name;.
  2. If the table has an autoincrement primary key, its sequence is not reset to zero, but that may occur in a future Tarantool version.
  3. There is no effect for any triggers associated with the table.
  4. There is no effect on the counts for the ROW_COUNT() function.
  5. Only one action is written to the write-ahead log (with DELETE FROM table-name; there would be one action for each deleted row).

Пример:

TRUNCATE TABLE t;

SET

Syntax:

  • SET SESSION setting-name = setting-value;
../../../_images/set.svg

SET SESSION is a shorthand way to update the box.space._session_settings temporary system space.

setting-name can have the following values:

  • "sql_default_engine"
  • "sql_full_column_names"
  • "sql_full_metadata"
  • "sql_parser_debug"
  • "sql_recursive_triggers"
  • "sql_reverse_unordered_selects"
  • "sql_select_debug"
  • "sql_vdbe_debug"
  • "sql_defer_foreign_keys" (removed in 2.11.0)
  • "error_marshaling_enabled" (removed in 2.10.0)

The quote marks are necessary.

If setting-name is "sql_default_engine", then setting-value can be either „vinyl“ or „memtx“. Otherwise, setting-value can be either TRUE or FALSE.

Example: SET SESSION "sql_default_engine" = 'vinyl'; changes the default engine to „vinyl“ instead of „memtx“, and returns:

---
- row_count: 1
...

It is functionally the same thing as an UPDATE Statement:

UPDATE "_session_settings"
SET "value" = 'vinyl'
WHERE "name" = 'sql_default_engine';

Statements that retrieve data

SELECT

Syntax:

SELECT [ALL|DISTINCT] select list [from clause] [where clause] [group-by clause] [having clause] [order-by clause];


../../../_images/select.svg


Select zero or more rows.

The clauses of the SELECT statement are discussed in the following five sections.

Select list

Syntax:

select-list-column [, select-list-column ...]

select-list-column:

../../../_images/select_list.svg


Define what will be in a result set; this is a clause in a SELECT statement.

The select list is a comma-delimited list of expressions, or * (asterisk). An expression can have an alias provided with an [[AS] column-name] clause.

The * «asterisk» shorthand is valid if and only if the SELECT statement also contains a FROM clause which specifies the table or tables (details about the FROM clause are in the next section). The simple form is * which means «all columns» – for example, if the select is done for a table which contains three columns s1 s2 s3, then SELECT * ... is equivalent to SELECT s1, s2, s3 .... The qualified form is table-name.* which means «all columns in the specified table», which again must be a result of the FROM clause – for example, if the table is named table1, then table1.* is equivalent to a list of the columns of table1.

The [[AS] column-name] clause determines the column name. The column name is useful for two reasons:

  • in a tabular display, the column names are the headings
  • if the results of the SELECT are used when creating a new table (such as a view), then the column names in the new table will be the column names in the select list.

If [[AS] column-name] is missing, and the expression is not simply the name of a column in the table, then Tarantool makes a name COLUMN_n where n is the number of the non-simple expression within the select list, for example SELECT 5.88, table1.x, 'b' COLLATE "unicode_ci" FROM table1; will cause the column names to be COLUMN_1, X, COLUMN_2. This is a behavior change since version 2.5.1. In earlier versions, the name would be equal to the expression; see Issue#3962. It is still legal to define tables with column names like COLUMN_1 but not recommended.

Примеры:

-- the simple form:
SELECT 5;
-- with multiple expressions including operators:
SELECT 1, 2 * 2, 'Three' || 'Four';
-- with [[AS] column-name] clause:
SELECT 5 AS column1;
-- * which must be eventually followed by a FROM clause:
SELECT * FROM table1;
-- as a list:
SELECT 1 AS a, 2 AS b, table1.* FROM table1;

FROM clause

Syntax:

FROM [SEQSCAN] table-reference [, table-reference ...]


../../../_images/from.svg


Specify the table or tables for the source of a SELECT statement.

The table-reference must be a name of an existing table, or a subquery, or a joined table.

A joined table looks like this:

table-reference-or-joined-table join-operator table-reference-or-joined-table [join-specification]

A join-operator must be any of the standard types:

  • [NATURAL] LEFT [OUTER] JOIN,
  • [NATURAL] INNER JOIN, or
  • CROSS JOIN

A join-specification must be any of:

  • ON expression, or
  • USING (column-name [, column-name …])

Parentheses are allowed, and [[AS] correlation-name] is allowed.

The maximum number of joins in a FROM clause is 64.

The SEQSCAN keyword (since 2.11) marks the queries that perform sequential scans during the execution. It happens if the query can’t use indexes, and goes through all the table rows one by one, sometimes causing a heavy load. Such queries are called scan queries. If a scan query doesn’t have the SEQSCAN keyword, Tarantool raises an error. SEQSCAN must precede all names of the tables that the query scans.

To find out if a query performs a sequential scan, use EXPLAIN QUERY PLAN. For scan queries, the result contains SCAN TABLE table_name.

Примечание

For backward compatibility, the scan queries without the SEQSCAN keyword are allowed in Tarantool 2.11. The errors on scan queries are the default behavior starting from 3.0. You can change the default behavior of scan queries using the compat option sql_seq_scan.

Примеры:

-- the simplest form:
SELECT * FROM SEQSCAN t;
-- with two tables, making a Cartesian join:
SELECT * FROM SEQSCAN t1, SEQSCAN t2;
-- with one table joined to itself, requiring correlation names:
SELECT a.*, b.* FROM SEQSCAN t1 AS a, SEQSCAN t1 AS b;
-- with a left outer join:
SELECT * FROM SEQSCAN t1 LEFT JOIN SEQSCAN t2;

WHERE clause

Syntax:

WHERE condition;


../../../_images/where.svg


Specify the condition for filtering rows from a table; this is a clause in a SELECT or UPDATE or DELETE statement.

The condition may contain any expression that returns a BOOLEAN (TRUE or FALSE or UNKNOWN) value.

For each row in the table:

  • if the condition is true, then the row is kept;
  • if the condition is false or unknown, then the row is ignored.

In effect, WHERE condition takes a table with n rows and returns a table with n or fewer rows.

Примеры:

-- with a simple condition:
SELECT 1 FROM t WHERE column1 = 5;
-- with a condition that contains AND and OR and parentheses:
SELECT 1 FROM t WHERE column1 = 5 AND (x > 1 OR y < 1);

GROUP BY clause

Syntax:

GROUP BY expression [, expression ...]


../../../_images/group_by.svg


Make a grouped table; this is a clause in a SELECT statement.

The expressions should be column names in the table, and each column should be specified only once.

In effect, the GROUP BY clause takes a table with rows that may have matching values, combines rows that have matching values into single rows, and returns a table which, because it is the result of GROUP BY, is called a grouped table.

Thus, if the input is a table:

a    b      c
-    -      -
1    'a'   'b
1    'b'   'b'
2    'a'   'b'
3    'a'   'b'
1    'b'   'b'

then GROUP BY a, b will produce a grouped table:

a    b      c
-    -      -
1    'a'   'b'
1    'b'   'b'
2    'a'   'b'
3    'a'   'b'

The rows where column a and column b have the same value have been merged; column c has been preserved but its value should not be depended on – if the rows were not all „b“, Tarantool could pick any value.

It is useful to envisage a grouped table as having hidden extra columns for the aggregation of the values, for example:

a    b      c    COUNT(a) SUM(a) MIN(c)
-    -      -    -------- ------ ------
1    'a'    'b'         2      2    'b'
1    'b'    'b'         1      1    'b'
2    'a'    'b'         1      2    'b'
     'a'    'b'         1      3    'b'

These extra columns are what aggregate functions are for.

Примеры:

-- with a single column:
SELECT 1 FROM t GROUP BY column1;
-- with two columns:
SELECT 1 FROM t GROUP BY column1, column2;

Limitations:

  • SELECT s1, s2 FROM t GROUP BY s1; is legal.
  • SELECT s1 AS q FROM t GROUP BY q; is legal.
  • SELECT s1 FROM t GROUP by 1; is legal.

Aggregate functions

Syntax:

function-name (one or more expressions)

Apply a built-in aggregate function to one or more expressions and return a scalar value.

Aggregate functions are only legal in certain clauses of a SELECT statement for grouped tables. (A table is a grouped table if a GROUP BY clause is present.) Also, if an aggregate function is used in a select list and the GROUP BY clause is omitted, then Tarantool assumes SELECT ... GROUP BY [all columns];.

NULLs are ignored for all aggregate functions except COUNT(*).

AVG([DISTINCT] expression)

Return the average value of expression.

Example: AVG(column1)

COUNT([DISTINCT] expression)

Return the number of occurrences of expression.

Example: COUNT(column1)

COUNT(*)

Return the number of occurrences of a row.

Example: COUNT(*)

GROUP_CONCAT(expression-1 [, expression-2]) or GROUP_CONCAT(DISTINCT expression-1)

Return a list of expression-1 values, separated by commas if expression-2 is omitted, or separated by the expression-2 value if expression-2 is not omitted.

Example: GROUP_CONCAT(column1)

MAX([DISTINCT] expression)

Return the maximum value of expression.

Example: MAX(column1)

MIN([DISTINCT] expression)

Return the minimum value of expression.

Example: MIN(column1)

SUM([DISTINCT] expression)

Возвращает сумму значений выражения или NULL, если строк не было.

Example: SUM(column1)

TOTAL([DISTINCT] expression)

Возвращает сумму значений выражения или ноль, если строк не было.

Example: TOTAL(column1)

HAVING clause

Syntax:

HAVING condition;


../../../_images/having.svg


Specify the condition for filtering rows from a grouped table; this is a clause in a SELECT statement.

The clause preceding the HAVING clause may be a GROUP BY clause. HAVING operates on the table that the GROUP BY produces, which may contain grouped columns and aggregates.

If the preceding clause is not a GROUP BY clause, then there is only one group and the HAVING clause may only contain aggregate functions or literals.

For each row in the table:

  • if the condition is true, then the row is kept;
  • if the condition is false or unknown, then the row is ignored.

In effect, HAVING condition takes a table with n rows and returns a table with n or fewer rows.

Примеры:

-- with a simple condition:
SELECT 1 FROM t GROUP BY column1 HAVING column2 > 5;
-- with a more complicated condition:
SELECT 1 FROM t GROUP BY column1 HAVING column2 > 5 OR column2 < 5;
-- with an aggregate:
SELECT x, SUM(y) FROM t GROUP BY x HAVING SUM(y) > 0;
-- with no GROUP BY and an aggregate:
SELECT SUM(y) FROM t GROUP BY x HAVING MIN(y) < MAX(y);

Limitations:

  • HAVING without GROUP BY is not supported for multiple tables.

ORDER BY clause

Syntax:

ORDER BY expression [ASC|DESC] [, expression [ASC|DESC] ...]


../../../_images/order_by.svg


Put rows in order; this is a clause in a SELECT statement.

An ORDER BY expression has one of three types which are checked in order:

  1. Expression is a positive integer, representing the ordinal position of the column in the select list. For example, in the statement
    SELECT x, y, z FROM t ORDER BY 2;
    ORDER BY 2 means «order by the second column in the select list», which is y.
  2. Expression is a name of a column in the select list, which is determined by an AS clause. For example, in the statement
    SELECT x, y AS x, z FROM t ORDER BY x;
    ORDER BY x means «order by the column explicitly named x in the select list», which is the second column.
  3. Expression contains a name of a column in a table of the FROM clause. For example, in the statement
    SELECT x, y FROM t1 JOIN t2 ORDER BY z;
    ORDER BY z means «order by a column named z which is expected to be in table t1 or table t2».

If both tables contain a column named z, then Tarantool will choose the first column that it finds.

Выражение может содержать операторы и имена функций, а также конкретные значения. Например, в инструкции SELECT x, y FROM t ORDER BY UPPER(z); часть ORDER BY UPPER(z) означает «упорядочить по значениям столбца t.z, представленным в заглавном регистре». Вероятно, эта операция аналогична упорядочиванию с помощью одной из нечувствительных к регистру сортировок Tarantool.

Type 3 is illegal if the SELECT statement contains UNION or EXCEPT or INTERSECT.

If an ORDER BY clause contains multiple expressions, then expressions on the left are processed first and expressions on the right are processed only if necessary for tie-breaking. For example, in the statement
SELECT x, y FROM t ORDER BY x, y; if there are two rows which both have the same values for column x, then an additional check is made to see which row has a greater value for column y.

In effect, ORDER BY clause takes a table with rows that may be out of order, and returns a table with rows in order.

Sorting order:

  • The default order is ASC (ascending), the optional order is DESC (descending).
  • Первыми идут значения NULL, затем значения типа BOOLEAN, числовые значения, STRING, VARBINARY и, наконец, UUID.
  • Ordering does not matter for ARRAYs or MAPs or ANYs because they are not legal for comparisons.
  • Within STRINGs, ordering is according to collation.
  • Collation may be specified with a COLLATE clause within the ORDER BY column-list, or may be default.

Примеры:

-- with a single column:
SELECT 1 FROM t ORDER BY column1;
-- with two columns:
SELECT 1 FROM t ORDER BY column1, column2;
-- with a variety of data:
CREATE TABLE h (s1 NUMBER PRIMARY KEY, s2 SCALAR);
INSERT INTO h VALUES (7, 'A'), (4, 'a'), (-4, 'AZ'), (17, 17), (23, NULL);
INSERT INTO h VALUES (17.5, 'Д'), (1e+300, 'A'), (0, ''), (-1, '');
SELECT * FROM h ORDER BY s2 COLLATE "unicode_ci", s1;
-- The result of the above SELECT will be:
- - [23, null]
  - [17, 17]
  - [-1, '']
  - [0, '']
  - [4, 'a']
  - [7, 'A']
  - [1e+300, 'A']
  - [-4, 'AZ']
  - [17.5, 'Д']
...

Limitations:

  • ORDER BY 1 is legal. This is common but is not standard SQL nowadays.

LIMIT clause

Syntax:

  • LIMIT limit-expression [OFFSET offset-expression]
  • LIMIT offset-expression, limit-expression

Примечание

The above is not a typo: offset-expression and limit-expression are in reverse order if a comma is used.


../../../_images/limit.svg


Specify a maximum number of rows and a start row; this is a clause in a SELECT statement.

Expressions may contain integers and arithmetic operators or functions, for example ABS(-3 / 1). However, the result must be an integer value greater than or equal to zero.

Usually the LIMIT clause follows an ORDER BY clause, because otherwise Tarantool does not guarantee that rows are in order.

Примеры:

-- simple case:
SELECT * FROM t LIMIT 3;
-- both limit and order:
SELECT * FROM t LIMIT 3 OFFSET 1;
-- applied to a UNIONed result (LIMIT clause must be the final clause):
SELECT column1 FROM table1 UNION SELECT column1 FROM table2 ORDER BY 1 LIMIT 1;

Limitations:

  • If ORDER BY … LIMIT is used, then all order-by columns must be ASC or all must be DESC.

Subquery

Syntax:

A subquery has the same syntax as a SELECT statement or VALUES statement embedded inside a main statement.

Примечание

The SELECT and VALUES statements are called «queries» because they return answers, in the form of result sets.

Subqueries may be the second part of INSERT statements. For example:

INSERT INTO t2 SELECT a, b, c FROM t1;

Subqueries may be in the FROM clause of SELECT statements.

Subqueries may be expressions, or be inside expressions. In this case they must be parenthesized, and usually the number of rows must be 1. For example:

SELECT 1, (SELECT 5), 3 FROM t WHERE c1 * (SELECT COUNT(*) FROM t2) > 5;

Subqueries may be expressions on the right side of certain comparison operators, and in this unusual case the number of rows may be greater than 1. The comparison operators are: [NOT] EXISTS and [NOT] IN. For example:

DELETE FROM t WHERE s1 NOT IN (SELECT s2 FROM t);

Subqueries may refer to values in the outer query. In this case, the subquery is called a «correlated subquery».

Subqueries may refer to rows which are being updated or deleted by the main query. In that case, the subquery finds the matching rows first, before starting to update or delete. For example, after:

CREATE TABLE t (s1 INTEGER PRIMARY KEY, s2 INTEGER);
INSERT INTO t VALUES (1, 3), (2, 1);
DELETE FROM t WHERE s2 NOT IN (SELECT s1 FROM t);

only one of the rows is deleted, not both rows.

WITH clause

WITH clause (common table expression)

Syntax:

WITH temporary-table-name AS (subquery)
[, temporary-table-name AS (subquery)]
SELECT statement | INSERT statement | DELETE statement | UPDATE statement | REPLACE statement;


../../../_images/with.svg


WITH v AS (SELECT * FROM t) SELECT * FROM v;

is equivalent to creating a view and selecting from it:

CREATE VIEW v AS SELECT * FROM t;
SELECT * FROM v;

The difference is that a WITH-clause «view» is temporary and only useful within the same statement. No CREATE privilege is required.

The WITH-clause can also be thought of as a subquery that has a name. This is useful when the same subquery is being repeated. For example:

SELECT * FROM t WHERE a < (SELECT s1 FROM x) AND b < (SELECT s1 FROM x);

can be replaced with:

WITH s AS (SELECT s1 FROM x) SELECT * FROM t,s WHERE a < s.s1 AND b < s.s1;

This «factoring out» of a repeated expression is regarded as good practice.

Примеры:

WITH cte AS (VALUES (7, '') INSERT INTO j SELECT * FROM cte;
WITH cte AS (SELECT s1 AS x FROM k) SELECT * FROM cte;
WITH cte AS (SELECT COUNT(*) FROM k WHERE s2 < 'x' GROUP BY s3)
  UPDATE j SET s2 = 5
  WHERE s1 = (SELECT s1 FROM cte) OR s3 = (SELECT s1 FROM cte);

WITH can only be used at the beginning of a statement, therefore it cannot be used at the beginning of a subquery or after a set operator or inside a CREATE statement.

A WITH-clause «view» is read-only because Tarantool does not support updatable views.

WITH RECURSIVE

WITH RECURSIVE clause (iterative common table expression)

The real power of WITH lies in the WITH RECURSIVE clause, which is useful when it is combined with UNION or UNION ALL:

WITH RECURSIVE recursive-table-name AS
(SELECT ... FROM non-recursive-table-name ...
UNION [ALL]
SELECT ... FROM recursive-table-name ...)
statement-that-uses-recursive-table-name;


../../../_images/with_recursive.svg


In non-SQL this can be read as: starting with a seed value from a non-recursive table, produce a recursive viewed table, UNION that with itself, UNION that with itself, UNION that with itself … forever, or until a condition in the WHERE clause says «stop».

Пример:

CREATE TABLE ts (s1 INTEGER PRIMARY KEY);
INSERT INTO ts VALUES (1);
WITH RECURSIVE w AS (
  SELECT s1 FROM ts
  UNION ALL
  SELECT s1 + 1 FROM w WHERE s1 < 4)
SELECT * FROM w;

First, table w is seeded from t1, so it has one row: [1].

Then, UNION ALL (SELECT s1 + 1 FROM w) takes the row from w – which contains [1] – adds 1 because the select list says «s1+1», and so it has one row: [2].

Then, UNION ALL (SELECT s1 + 1 FROM w) takes the row from w – which contains [2] – adds 1 because the select list says «s1+1», and so it has one row: [3].

Then, UNION ALL (SELECT s1 + 1 FROM w) takes the row from w – which contains [3] – adds 1 because the select list says «s1+1», and so it has one row: [4].

Then, UNION ALL (SELECT s1 + 1 FROM w) takes the row from w – which contains [4] – and now the importance of the WHERE clause becomes evident, because «s1 < 4» is false for this row, and therefore the «stop» condition has been reached.

So, before the «stop», table w got 4 rows – [1], [2], [3], [4] – and the result of the statement looks like:

tarantool> WITH RECURSIVE w AS (
         >   SELECT s1 FROM ts
         >   UNION ALL
         >   SELECT s1 + 1 FROM w WHERE s1 < 4)
         > SELECT * FROM w;
---
- - [1]
  - [2]
  - [3]
  - [4]
...

In other words, this WITH RECURSIVE ... SELECT produces a table of auto-incrementing values.

UNION, EXCEPT, and INTERSECT clauses

Syntax:

  • select-statement UNION [ALL] select-statement [ORDER BY clause] [LIMIT clause];
  • select-statement EXCEPT select-statement [ORDER BY clause] [LIMIT clause];
  • select-statement INTERSECT select-statement [ORDER BY clause] [LIMIT clause];


../../../_images/union.svg


../../../_images/except.svg


../../../_images/intersect.svg


UNION, EXCEPT, and INTERSECT are collectively called «set operators» or «table operators». In particular:

  • a UNION b means «take rows which occur in a OR b».
  • a EXCEPT b means «take rows which occur in a AND NOT b».
  • a INTERSECT b means «take rows which occur in a AND b».

Duplicate rows are eliminated unless ALL is specified.

The select-statements may be chained: SELECT ... SELECT ... SELECT ...;

Each select-statement must result in the same number of columns.

The select-statements may be replaced with VALUES statements.

The maximum number of set operations is 50.

Пример:

CREATE TABLE t1 (s1 INTEGER PRIMARY KEY, s2 STRING);
CREATE TABLE t2 (s1 INTEGER PRIMARY KEY, s2 STRING);
INSERT INTO t1 VALUES (1, 'A'), (2, 'B'), (3, NULL);
INSERT INTO t2 VALUES (1, 'A'), (2, 'C'), (3,NULL);
SELECT s2 FROM t1 UNION SELECT s2 FROM t2;
SELECT s2 FROM t1 UNION ALL SELECT s2 FROM t2 ORDER BY s2;
SELECT s2 FROM t1 EXCEPT SELECT s2 FROM t2;
SELECT s2 FROM t1 INTERSECT SELECT s2 FROM t2;

В данном примере:

  • The UNION query returns 4 rows: NULL, „A“, „B“, „C“.
  • The UNION ALL query returns 6 rows: NULL, NULL, „A“, „A“, „B“, „C“.
  • The EXCEPT query returns 1 row: „B“.
  • The INTERSECT query returns 2 rows: NULL, „A“.

Limitations:

  • Parentheses are not allowed.
  • Evaluation is left to right, INTERSECT does not have precedence.

Пример:

CREATE TABLE t01 (s1 INTEGER PRIMARY KEY, s2 STRING);
CREATE TABLE t02 (s1 INTEGER PRIMARY KEY, s2 STRING);
CREATE TABLE t03 (s1 INTEGER PRIMARY KEY, s2 STRING);
INSERT INTO t01 VALUES (1, 'A');
INSERT INTO t02 VALUES (1, 'B');
INSERT INTO t03 VALUES (1, 'A');
SELECT s2 FROM t01 INTERSECT SELECT s2 FROM t03 UNION SELECT s2 FROM t02;
SELECT s2 FROM t03 UNION SELECT s2 FROM t02 INTERSECT SELECT s2 FROM t03;
-- ... results are different.

INDEXED BY clause

Syntax:

INDEXED BY index-name


../../../_images/indexed_by.svg


The INDEXED BY clause may be used in a SELECT, DELETE, or UPDATE statement, immediately after the table-name. For example:

DELETE FROM table7 INDEXED BY index7 WHERE column1 = 'a';

In this case the search for „a“ will take place within index7. For example:

SELECT * FROM table7 NOT INDEXED WHERE column1 = 'a';

In this case the search for „a“ will be done via a search of the whole table, what is sometimes called a «full table scan», even if there is an index for column1.

Ordinarily Tarantool chooses the appropriate index or lookup method depending on a complex set of «optimizer» rules; the INDEXED BY clause overrides the optimizer choice. If the index was defined with the exclude_null parts option, it will only be used if the user specifies it.

Пример:

Suppose a table has two columns:

  • The first column is the primary key and therefore it has an automatic index named pk_unnamed_T_1.
  • The second column has an index created by the user.

The user selects with INDEXED BY the-index-on-column1, then selects with INDEXED BY the-index-on-column-2.

CREATE TABLE t (column1 INTEGER PRIMARY KEY, column2 INTEGER);
CREATE INDEX idx_column2_t_1 ON t (column2);
INSERT INTO t VALUES (1, 2), (2, 1);
SELECT * FROM t INDEXED BY "pk_unnamed_T_1";
SELECT * FROM t INDEXED BY idx_column2_t_1;
-- Result for the first select: (1, 2), (2, 1)
-- Result for the second select: (2, 1), (1, 2).

Limitations:
Often INDEXED BY has no effect.
Often INDEXED BY affects a choice of covering index, but not a WHERE clause.

VALUES

Syntax:

VALUES (expression [, expression ...]) [, (expression [, expression ...])


../../../_images/values.svg


Select one or more rows.

VALUES has the same effect as SELECT, that is, it returns a result set, but VALUES statements may not have FROM or GROUP or ORDER BY or LIMIT clauses.

VALUES may be used wherever SELECT may be used, for example in subqueries.

Примеры:

-- simple case:
VALUES (1);
-- equivalent to SELECT 1, 2, 3:
VALUES (1, 2, 3);
-- two rows:
VALUES (1, 2, 3), (4, 5, 6);

PRAGMA

Syntax:

  • PRAGMA pragma-name (pragma-value);
  • or PRAGMA pragma-name;
../../../_images/pragma.svg

PRAGMA statements will give rudimentary information about database „metadata“ or server performance, although it is better to get metadata via system tables.

For PRAGMA statements that include (pragma-value), pragma values are strings and can be specified inside "" double quotes, or without quotes. When a string is used for searching, results must match according to a binary collation. If the object being searched has a lower-case name, use double quotes.

In an earlier version, there were some PRAGMA statements that determined behavior. Now that does not happen. Behavior change is done by updating the box.space._session_settings system table.

Pragma Parameter Эффект
foreign_key_list string
table-name		 Return a result set with one row for each foreign key of «table-name». Each row contains:
(INTEGER) id – identification number
(INTEGER) seq – sequential number
(STRING) table – name of table
(STRING) from – referencing key
(STRING) to – referenced key
(STRING) on_update – ON UPDATE clause
(STRING) on_delete – ON DELETE clause
(STRING) match – MATCH clause
The system table is "_fk_constraint".
collation_list   Return a result set with one row for each supported collation. The first four collations are 'none' and 'unicode' and 'unicode_ci' and 'binary', then come about 270 predefined collations, the exact count may vary because users can add their own collations.
The system table is "_collation".
index_info string
table-name . index-name		 Return a result set with one row for each column in «table-name.index-name». Each row contains:
(INTEGER) seqno – the column’s ordinal position in the index (first column is 0)
(INTEGER) cid – the column’s ordinal position in the table (first column is 0)
(STRING) name – name of the column
(INTEGER) desc – 0 is ASC, 1 is DESC
(STRING) collation name
(STRING) type – data type
index_list string
table-name		 Return a result set with one row for each index of «table-name». Each row contains:
(INTEGER) seq – sequential number
(STRING) name – index name
(INTEGER) unique – whether the index is unique, 0 is false, 1 is true
The system table is "_index".
stats   Return a result set with one row for each index of each table. Each row contains:
(STRING) table – name of the table
(STRING) index – name of the index
(INTEGER) width – arbitrary information
(INTEGER) height – arbitrary information
table_info string
table-name		 Return a result set with one row for each column in «table-name». Each row contains:
(INTEGER) cid – ordinal position in the table
(first column number is 0)
(STRING) name – column name
(STRING) type
(INTEGER) notnull – whether the column is NOT NULL, 0 is false, 1 is true.
(STRING) dflt_value – default value
(INTEGER) pk – whether the column is a PRIMARY KEY column, 0 is false, 1 is true.

Example: (not showing result set metadata)

PRAGMA table_info(T);
---
- - [0, 's1', 'integer', 1, null, 1]
  - [1, 's2', 'integer', 0, null, 0]
...

EXPLAIN

Syntax:

  • EXPLAIN explainable-statement;
../../../_images/explain.svg

EXPLAIN will show what steps Tarantool would take if it executed explainable-statement. This is primarily a debugging and optimization aid for the Tarantool team.

Example: EXPLAIN DELETE FROM m; returns:

- - [0, 'Init', 0, 3, 0, '', '00', 'Start at 3']
  - [1, 'Clear', 16416, 0, 0, '', '00', '']
  - [2, 'Halt', 0, 0, 0, '', '00', '']
  - [3, 'Transaction', 0, 1, 1, '0', '01', 'usesStmtJournal=0']
  - [4, 'Goto', 0, 1, 0, '', '00', '']

Variation: EXPLAIN QUERY PLAN statement; shows the steps of a search.

Statements for transactions

START TRANSACTION

Syntax:

START TRANSACTION;


../../../_images/start.svg


Start a transaction. After START TRANSACTION;, a transaction is «active». If a transaction is already active, then START TRANSACTION; is illegal.

Transactions should be active for fairly short periods of time, to avoid concurrency issues. To end a transaction, say COMMIT; or ROLLBACK;.

Just as in NoSQL, transaction control statements are subject to limitations set by the storage engine involved:
* For the memtx storage engine, if a yield happens within an active transaction, the transaction is rolled back.
* For the vinyl engine, yields are allowed.
Also, although CREATE AND DROP and ALTER statements are legal in transactions, there are a few exceptions. For example, CREATE INDEX ON table_name ... will fail within a multi-statement transaction if the table is not empty.

Однако инструкции управления транзакциями всё еще могут работать не так, как вы ожидаете при запуске через сетевое соединение: транзакция связана с файбером, а не с сетевым соединением, и разные инструкции управления транзакциями, отправленные через одно и то же сетевое соединение, могут быть выполнены разными файберами из пула файберов.

In order to ensure that all statements are part of the intended transaction, put all of them between START TRANSACTION; and COMMIT; or ROLLBACK; then send as a single batch. For example:

  • Enclose each separate SQL statement in a box.execute() function.

  • Pass all the box.execute() functions to the server in a single message.

    If you are using a console, you can do this by writing everything on a single line.

    If you are using net.box, you can do this by putting all the function calls in a single string and calling eval(string).

Пример:

START TRANSACTION;

Example of a whole transaction sent to a server on localhost:3301 with eval(string):

net_box = require('net.box')
conn = net_box.new('localhost', 3301)
s = 'box.execute([[START TRANSACTION;]]) '
s = s .. 'box.execute([[INSERT INTO t VALUES (1);]]) '
s = s .. 'box.execute([[ROLLBACK;]]) '
conn:eval(s)

COMMIT

Syntax:

COMMIT;


../../../_images/commit.svg


Commit an active transaction, so all changes are made permanent and the transaction ends.

COMMIT is illegal unless a transaction is active. If a transaction is not active then SQL statements are committed automatically.

Пример:

COMMIT;

SAVEPOINT

Syntax:

SAVEPOINT savepoint-name;


../../../_images/savepoint.svg


Set a savepoint, so that ROLLBACK TO savepoint-name is possible.

SAVEPOINT is illegal unless a transaction is active.

If a savepoint with the same name already exists, it is released before the new savepoint is set.

Пример:

SAVEPOINT x;

RELEASE SAVEPOINT

Syntax:

RELEASE SAVEPOINT savepoint-name;


../../../_images/release.svg


Release (destroy) a savepoint created by a SAVEPOINT statement.

RELEASE is illegal unless a transaction is active.

Savepoints are released automatically when a transaction ends.

Пример:

RELEASE SAVEPOINT x;

ROLLBACK

Syntax:

ROLLBACK [TO [SAVEPOINT] savepoint-name];


../../../_images/rollback.svg


If ROLLBACK does not specify a savepoint-name, rollback an active transaction, so all changes since START TRANSACTION are cancelled, and the transaction ends.

If ROLLBACK does specify a savepoint-name, rollback an active transaction, so all changes since SAVEPOINT savepoint-name are cancelled, and the transaction does not end.

ROLLBACK is illegal unless a transaction is active.

Примеры:

-- the simple form:
ROLLBACK;
-- the form so changes before a savepoint are not cancelled:
ROLLBACK TO SAVEPOINT x;

-- An example of a Lua function that will do a transaction
-- containing savepoint and rollback to savepoint.
function f()
box.execute([[DROP TABLE IF EXISTS t;]]) -- commits automatically
box.execute([[CREATE TABLE t (s1 STRING PRIMARY KEY);]]) -- commits automatically
box.execute([[START TRANSACTION;]]) -- after this succeeds, a transaction is active
box.execute([[INSERT INTO t VALUES ('Data change #1');]])
box.execute([[SAVEPOINT "1";]])
box.execute([[INSERT INTO t VALUES ('Data change #2');]])
box.execute([[ROLLBACK TO SAVEPOINT "1";]]) -- rollback Data change #2
box.execute([[ROLLBACK TO SAVEPOINT "1";]]) -- this is legal but does nothing
box.execute([[COMMIT;]]) -- make Data change #1 permanent, end the transaction
end

Functions

Explanation of functions

Syntax:

function-name (one or more expressions)

Apply a built-in function to one or more expressions and return a scalar value.

Tarantool поддерживает 33 встроенные функции.

The maximum number of operands for any function is 127.

The required privileges for built-in functions will likely change in a future version.

List of functions

Ниже приведены встроенные функции Tarantool/SQL. Начиная с Tarantool 2.10 для функций, требующих числовые аргументы, аргументы с типом данных NUMBER недопустимы.

ABS

Syntax:

ABS(numeric-expression)

Return the absolute value of numeric-expression, which can be any numeric type.

Example: ABS(-1) is 1.

CAST

Syntax:

CAST(expression AS data-type)

Return the expression value after casting to the specified data type.

CAST в или из UUID может поменять порядок байтов на little-endian или обратно.

Examples: CAST('AB' AS VARBINARY), CAST(X'4142' AS STRING)

CHAR

Syntax:

CHAR([numeric-expression [,numeric-expression...])

Return the characters whose Unicode code point values are equal to the numeric expressions.

Short example:

The first 128 Unicode characters are the «ASCII» characters, so CHAR(65, 66, 67) is „ABC“.

Long example:

For the current list of Unicode characters, in order by code point, see www.unicode.org/Public/UCD/latest/ucd/UnicodeData.txt. In that list, there is a line for a Linear B ideogram

100CC;LINEAR B IDEOGRAM B240 WHEELED CHARIOT ...

Therefore, for a string with a chariot in the middle, use the concatenation operator || and the CHAR function

'start of string ' || CHAR(0X100CC) || ' end of string'.

COALESCE

Syntax:

COALESCE(expression, expression [, expression ...])

Return the value of the first non-NULL expression, or, if all expression values are NULL, return NULL.

Пример:
COALESCE(NULL, 17, 32) is 17.

DATE_PART

Syntax:

DATE_PART(value_requested , datetime)

Since 2.10.0.

The DATE_PART() function returns the requested information from a DATETIME value. It takes two arguments: the first one tells us what information is requested, the second is a DATETIME value.

Below is a list of supported values of the first argument and what information is returned:

  • millennium – millennium
  • century – century
  • decade – decade
  • year – year
  • quarter – quarter of year
  • month – month of year
  • week – week of year
  • day – day of month
  • dow – day of week
  • doy – day of year
  • hour – hour of day
  • minute – minute of hour
  • second – second of minute
  • millisecond – millisecond of second
  • microsecond – microsecond of second
  • nanosecond – nanosecond of second
  • epoch – epoch
  • timezone_offset – time zone offset from the UTC, in minutes.

Примеры:

tarantool> select date_part('millennium', cast({'year': 2000, 'month': 4, 'day': 5, 'hour': 6, 'min': 33, 'sec': 22, 'nsec': 523999111} as datetime));
---
- metadata:
  - name: COLUMN_1
    type: integer
  rows:
  - [2]
...

tarantool> select date_part('day', cast({'year': 2000, 'month': 4, 'day': 5, 'hour': 6, 'min': 33, 'sec': 22, 'nsec': 523999111} as datetime));
---
- metadata:
  - name: COLUMN_1
    type: integer
  rows:
  - [5]
...

tarantool> select date_part('nanosecond', cast({'year': 2000, 'month': 4, 'day': 5, 'hour': 6, 'min': 33, 'sec': 22, 'nsec': 523999111} as datetime));
---
- metadata:
  - name: COLUMN_1
    type: integer
  rows:
  - [523999111]
...

GREATEST

Syntax:

GREATEST(expression-1, expression-2, [expression-3 ...])

Return the greatest value of the supplied expressions, or, if any expression is NULL, return NULL. The reverse of GREATEST is LEAST.

Examples: GREATEST(7, 44, -1) is 44; GREATEST(1E308, 'a', 0, X'00') is „0“ = the nul character; GREATEST(3, NULL, 2) is NULL

HEX

Syntax:

HEX(expression)

Возвращает шестнадцатеричный код для каждого байта выражения expression.

Начиная с версии Tarantool 2.10.0 выражение должно быть последовательностью байтов (тип данных VARBINARY).

В предыдущих версиях Tarantool выражение могло быть либо строкой, либо последовательностью байтов. Для символов ASCII оно выполнялось довольно прямолинейно, поскольку значение каждого символа в кодировке ASCII совпадает с его значением в шестнадцатеричной схеме. В случае с символами, не входящими в таблицу ASCII, для каждого символа потребуется два байта или более, поскольку строки символов обычно кодируются в UTF-8.

Примеры:

  • HEX(X'41') вернет 41.
  • HEX(CAST('Д' AS VARBINARY)) вернет D094.

IFNULL

Syntax:

IFNULL(expression, expression)

Return the value of the first non-NULL expression, or, if both expression values are NULL, return NULL. Thus IFNULL(expression, expression) is the same as COALESCE(expression, expression).

Пример:
IFNULL(NULL, 17) is 17

LEAST

Syntax:

LEAST(expression-1, expression-2, [expression-3 ...])

Return the least value of the supplied expressions, or, if any expression is NULL, return NULL. The reverse of LEAST is GREATEST.

Examples: LEAST(7, 44, -1) is -1; LEAST(1E308, 'a', 0, X'00') is 0; LEAST(3, NULL, 2) is NULL.

LENGTH

Syntax:

LENGTH(expression)

Return the number of characters in the expression, or the number of bytes in the expression. It depends on the data type: strings with data type STRING are counted in characters, byte sequences with data type VARBINARY are counted in bytes and are not ended by the nul character. There are two aliases for LENGTH(expression) – CHAR_LENGTH(expression) and CHARACTER_LENGTH(expression) do the same thing.

Примеры:

  • LENGTH('ДД') is 2, the string has 2 characters.
  • LENGTH(CAST('ДД' AS VARBINARY)) is 4, the string has 4 bytes.
  • LENGTH(CHAR(0, 65)) is 2, „0“ does not mean „end of string“.
  • LENGTH(X'410041') is 3, X“…“ byte sequences have type VARBINARY.

LIKELIHOOD

Syntax:

LIKELIHOOD(expression, DOUBLE literal)

Возвращает выражение без изменений, при условии, что числовое значение находится в диапазоне от 0.0 до 1.0.

Example: LIKELIHOOD('a' = 'b', .0) is FALSE

LIKELY

Syntax:

LIKELY(expression)

Return TRUE if the expression is probably true.

Example: LIKELY('a' <= 'b') is TRUE

LOWER

Syntax:

LOWER(string-expression)

Return the expression, with upper-case characters converted to lower case. The reverse of LOWER is UPPER.

Example: LOWER('ДA') is „дa“

NOW

Syntax:

NOW()

Since 2.10.0.

The NOW() function returns the current date and time as a DATETIME value.

If the function is called more than once in a query, it returns the same result until the query completes, unless a yield has occurred. On yield, the value returned by NOW() is changing.

Примеры:

tarantool> select now(), now(), now()
---
- metadata:
  - name: COLUMN_1
    type: datetime
  - name: COLUMN_2
    type: datetime
  - name: COLUMN_3
    type: datetime
  rows:
  - ['2022-07-20T19:02:02.010812282+0300', '2022-07-20T19:02:02.010812282+0300', '2022-07-20T19:02:02.010812282+0300']
...

NULLIF

Syntax:

NULLIF(expression-1, expression-2)

Return expression-1 if expression-1 <> expression-2, otherwise return NULL.

Примеры:

  • NULLIF('a', 'A') is „a“.
  • NULLIF(1.00, 1) is NULL.

Примечание

Before Tarantool 2.10.4, the type of the result was always SCALAR. Since Tarantool 2.10.4, the result of NULLIF matches the type of the first argument. If the first argument is the NULL literal, then the result has the SCALAR type.

POSITION

Syntax:

POSITION(expression-1, expression-2)

Return the position of expression-1 within expression-2, or return 0 if expression-1 does not appear within expression-2. The data types of the expressions must be either STRING or VARBINARY. If the expressions have data type STRING, then the result is the character position. If the expressions have data type VARBINARY, then the result is the byte position.

Short example: POSITION('C', 'ABC') is 3

Long example: The UTF-8 encoding for the Latin letter A is hexadecimal 41; the UTF-8 encoding for the Cyrillic letter Д is hexadecimal D094 – you can confirm this by saying SELECT HEX(„ДA“); and seeing that the result is „D09441“. If you now execute SELECT POSITION('A', 'ДA'); the result will be 2, because „A“ is the second character in the string. However, if you now execute SELECT POSITION(X'41', X'D09441'); the result will be 3, because X’41“ is the third byte in the byte sequence.

PRINTF

Syntax:

PRINTF(string-expression [, expression ...])

Возвращает строку, отформатированную по правилам функции C sprintf(), где %d%s означает, что следующие два аргумента — числовой и строка, и так далее.

If an argument is missing or is NULL, it becomes:

  • „0“ if the format requires an integer,
  • '0.0', если формат требует числового значения с десятичной точкой,
  • „“ if the format requires a string.

Example: PRINTF('%da', 5) is „5a“.

QUOTE

Syntax:

QUOTE(string)

Return a string with enclosing quotes if necessary, and with quotes inside the enclosing quotes if necessary. This function is useful for creating strings which are part of SQL statements, because of SQL’s rules that string literals are enclosed by single quotes, and single quotes inside such strings are shown as two single quotes in a row.

Начиная с версии Tarantool 2.10 аргументы с числовыми типами данных возвращаются без изменений.

Примеры: QUOTE('a') вернет 'a', QUOTE(5) вернет 5.

RAISE

Syntax:

RAISE(FAIL, error-message)

This may only be used within a triggered statement. See also Trigger Activation.

RANDOM

Syntax: RANDOM()

Return a 19-digit integer which is generated by a pseudo-random number generator,

Example: RANDOM() is 6832175749978026034, or it is any other integer

RANDOMBLOB

Syntax:

RANDOMBLOB(n)

Return a byte sequence, n bytes long, data type = VARBINARY, containing bytes generated by a pseudo-random byte generator. The result can be translated to hexadecimal. If n is less than 1 or is NULL or is infinity, then NULL is returned.

Example: HEX(RANDOMBLOB(3)) is „9EAAA8“, or it is the hex value for any other three-byte string

REPLACE

Syntax:

REPLACE(expression-1, expression-2, expression-3)

Return expression-1, except that wherever expression-1 contains expression-2, replace expression-2 with expression-3. The expressions should all have data type STRING or VARBINARY.

Example: REPLACE('AAABCCCBD', 'B', '!') is „AAA!CCC!D“

ROUND

Syntax:

ROUND(numeric-expression-1 [, numeric-expression-2])

Возвращает округленное значение первого числового выражения. Положительные числа округляются до 0,5 в большую сторону, отрицательные — до 0,5 в меньшую. Если задано второе числовое выражение, то первое округляется до ближайших цифр после десятичной точки второго выражения. Если второе выражение не задано, первое округляется до ближайшего целого числа.

Example: ROUND(-1.5) is -2, ROUND(1.7766E1,2) is 17.77.

ROW_COUNT

ROW_COUNT()

Return the number of rows that were inserted / updated / deleted by the last INSERT or UPDATE or DELETE or REPLACE statement. Rows which were updated by an UPDATE statement are counted even if there was no change. Rows which were inserted / updated / deleted due to foreign-key action are not counted. Rows which were inserted / updated / deleted due to a view’s INSTEAD OF triggers are not counted. After a CREATE or DROP statement, ROW_COUNT() is 1. After other statements, ROW_COUNT() is 0.

Example: ROW_COUNT() is 1 after a successful INSERT of a single row.

Special rule if there are BEFORE or AFTER triggers: In effect the ROW_COUNT() counter is pushed at the beginning of a series of triggered statements, and popped at the end. Therefore, after the following statements:

CREATE TABLE t1 (s1 INTEGER PRIMARY KEY);
CREATE TABLE t2 (s1 INTEGER, s2 STRING, s3 INTEGER, PRIMARY KEY (s1, s2, s3));
CREATE TRIGGER tt1 BEFORE DELETE ON t1 FOR EACH ROW BEGIN
  INSERT INTO t2 VALUES (old.s1, '#2 Triggered', ROW_COUNT());
  INSERT INTO t2 VALUES (old.s1, '#3 Triggered', ROW_COUNT());
  END;
INSERT INTO t1 VALUES (1),(2),(3);
DELETE FROM t1;
INSERT INTO t2 VALUES (4, '#4 Untriggered', ROW_COUNT());
SELECT * FROM t2;

The result is:

---
- - [1, '#2 Triggered', 3]
  - [1, '#3 Triggered', 1]
  - [2, '#2 Triggered', 3]
  - [2, '#3 Triggered', 1]
  - [3, '#2 Triggered', 3]
  - [3, '#3 Triggered', 1]
  - [4, '#4 Untriggered', 3]
...

SOUNDEX

Syntax:

SOUNDEX(string-expression)

Return a four-character string which represents the sound of string-expression. Often words and names which have different spellings will have the same Soundex representation if they are pronounced similarly, so it is possible to search by what they sound like. The algorithm works with characters in the Latin alphabet and works best with English words.

Example: SOUNDEX('Crater') and SOUNDEX('Creature') both return C636.

SUBSTR

Syntax:

SUBSTR(string-or-varbinary-value, numeric-start-position [, numeric-length])

If string-or-varbinary-value has data type STRING, then return the substring which begins at character position numeric-start-position and continues for numeric-length characters (if numeric-length is supplied), or continues till the end of string-or-varbinary-value (if numeric-length is not supplied).

If numeric-start-position is less than 1, or if numeric-start-position + numeric-length is greater than the length of string-or-varbinary-value, then the result is not an error, anything which would be before the start or after the end is ignored. There are no symbols with index <= 0 or with index greater than the length of the first argument.

If numeric-length is less than 0, then the result is an error.

If string-or-varbinary-value has data type VARBINARY rather than data type STRING, then positioning and counting is by bytes rather than by characters.

Examples: SUBSTR('ABCDEF', 3, 2) is „CD“, SUBSTR('абвгде', -1, 4) is „аб“

TRIM

Syntax:

TRIM([[LEADING|TRAILING|BOTH] [expression-1] FROM] expression-2)

Return expression-2 after removing all leading and/or trailing characters or bytes. The expressions should have data type STRING or VARBINARY. If LEADING|TRAILING|BOTH is omitted, the default is BOTH. If expression-1 is omitted, the default is „ „ (space) for data type STRING or X’00“ (nul) for data type VARBINARY.

Примеры:

TRIM('a' FROM 'abaaaaa') is „b“ – all repetitions of „a“ are removed on both sides; TRIM(TRAILING 'ב' FROM 'אב') is „א“ – if all characters are Hebrew, TRAILING means «left»; TRIM(X'004400') is X’44“ – the default byte sequence to trim is X’00“ when data type is VARBINARY; TRIM(LEADING 'abc' FROM 'abcd') is „d“ – expression-1 can have more than 1 character.

TYPEOF

Syntax:

TYPEOF(expression)

Возвращает 'NULL', если выражение равно NULL. Возвращает 'scalar', если выражение — это имя колонки, определенной как SCALAR. В остальных случаях возвращает тип данных выражения.

Примеры:

TYPEOF('A') вернет 'string'; TYPEOF(RANDOMBLOB(1)) вернет 'varbinary'; TYPEOF(1e44) вернет 'double' или 'number'; TYPEOF(-44) вернет 'integer'; TYPEOF(NULL) вернет 'NULL'.

До версии Tarantool 2.10 TYPEOF(выражение) возвращало тип данных результата выражения во всех случаях.

UNICODE

Syntax:

UNICODE(string-expression)

Return the Unicode code point value of the first character of string-expression. If string-expression is empty, the return is NULL. This is the reverse of CHAR(integer).

Example: UNICODE('Щ') is 1065 (hexadecimal 0429).

UNLIKELY

Syntax:

UNLIKELY(expression)

Return TRUE if the expression is probably false. Limitation: in fact UNLIKELY may return the same thing as LIKELY.

Example: UNLIKELY('a' <= 'b') is TRUE.

UPPER

Syntax:

UPPER(string-expression)

Return the expression, with lower-case characters converted to upper case. The reverse of UPPER is LOWER.

Example: UPPER('-4щl') is „-4ЩL“.

UUID

Syntax:

UUID([integer])

Возвращает универсальный уникальный идентификатор, тип данных UUID. Опционально можно указать номер версии, однако на данный момент единственной возможной версией является 4, которая установлена по умолчанию. Поддержка UUID в SQL была добавлена в версии Tarantool 2.9.1.

Пример: UUID() или UUID(4)

VERSION

Syntax:

VERSION()

Return the Tarantool version.

Example: for a February 2020 build VERSION() is '2.4.0-35-g57f6fc932'.

ZEROBLOB

Syntax:

ZEROBLOB(n)

Return a byte sequence, data type = VARBINARY, n bytes long.

COLLATE clause

COLLATE collation-name

The collation-name must identify an existing collation.

The COLLATE clause is allowed for STRING or SCALAR items:
() in CREATE INDEX
() in CREATE TABLE as part of column definition
() in CREATE TABLE as part of UNIQUE definition
() in string expressions

Примеры:

-- In CREATE INDEX
CREATE INDEX idx_unicode_mb_1 ON mb (s1 COLLATE "unicode");
-- In CREATE TABLE
CREATE TABLE t1 (s1 INTEGER PRIMARY KEY, s2 STRING COLLATE "unicode_ci");
-- In CREATE TABLE ... UNIQUE
CREATE TABLE mb (a STRING, b STRING, PRIMARY KEY(a), UNIQUE(b COLLATE "unicode_ci" DESC));
-- In string expressions
SELECT 'a' = 'b' COLLATE "unicode"
    FROM t
    WHERE s1 = 'b' COLLATE "unicode"
    ORDER BY s1 COLLATE "unicode";

The list of collations can be seen with: PRAGMA collation_list;

The collation rules comply completely with the Unicode Technical Standard #10 («Unicode Collation Algorithm») and the default character order is as in the Default Unicode Collation Element Table (DUCET). There are many permanent collations; the commonly used ones include:
    "none" (not applicable)
    "unicode" (characters are in DUCET order with strength = „tertiary“)
    "unicode_ci" (characters are in DUCET order with strength = „primary“)
    "binary" (characters are in code point order)
These identifiers must be quoted and in lower case because they are in lower case in Tarantool/NoSQL collations.

If one says COLLATE "binary", this is equivalent to asking for what is sometimes called «code point order» because, if the contents are in the UTF-8 character set, characters with larger code points will appear after characters with lower code points.

In an expression, COLLATE is an operator with higher precedence than anything except ~. This is fine because there are no other useful operators except || and comparison. After ||, collation is preserved.

In an expression with more than one COLLATE clause, if the collation names differ, there is an error: «Illegal mix of collations». In an expression with no COLLATE clauses, literals have collation "binary", columns have the collation specified by CREATE TABLE.

In other words, to pick a collation, Tarantool uses:
the first COLLATE clause in an expression if it was specified,
else the column’s COLLATE clause if it was specified,
else "binary".

However, for searches and sometimes for sorting, the collation may be an index’s collation, so all non-index COLLATE clauses are ignored.

EXPLAIN will not show the name of what collation was used, but will show the collation’s characteristics.

Example with Swedish collation:
Knowing that «sv» is the two-letter code for Swedish,
and knowing that «s1» means strength = 1,
and seeing with PRAGMA collation_list; that there is a collation named unicode_sv_s1,
check whether two strings are equal according to Swedish rules (yes they are):
SELECT 'ÄÄ' = 'ĘĘ' COLLATE "unicode_sv_s1";

Example with Russian and Ukrainian and Kyrgyz collations:
Knowing that Russian collation is practically the same as Unicode default,
and knowing that the two-letter codes for Ukrainian and Kyrgyz are „uk“ and „ky“,
and knowing that in Russian (but not Ukrainian) „Г“ = „Ґ“ with strength=primary,
and knowing that in Russian (but not Kyrgyz) „Е“ = „Ё“ with strength=primary,
the three SELECT statements here will return results in three different orders:
CREATE TABLE things (remark STRING PRIMARY KEY);
INSERT INTO things VALUES ('Е2'), ('Ё1');
INSERT INTO things VALUES ('Г2'), ('Ґ1');
SELECT remark FROM things ORDER BY remark COLLATE "unicode";
SELECT remark FROM things ORDER BY remark COLLATE "unicode_uk_s1";
SELECT remark FROM things ORDER BY remark COLLATE "unicode_ky_s1";

Параметры функций по умолчанию

Starting in Tarantool 2.10, if a parameter for an aggregate function or a built-in scalar SQL function is one of the extra-parameters that can appear in box.execute(…[,extra-parameters]) requests, default data type is calculated thus:
* When there is only one possible data type, it is default.
Example: box.execute([[SELECT TYPEOF(LOWER(?));]],{x}) is „string“.
* When possible data types are INTEGER or DOUBLE or DECIMAL, DECIMAL is default.
Example: box.execute([[SELECT TYPEOF(AVG(?));]],{x}) is „decimal“.
* When possible data types are STRING or VARBINARY, STRING is default.
Example: box.execute([[SELECT TYPEOF(LENGTH(?));]],{x}) is „string“.
* When possible data types are any other scalar data type, SCALAR is default.
Example: box.execute([[SELECT TYPEOF(GREATEST(?,5));]],{x}) is „scalar“.
* When possible data type is a non-scalar data type, such as ARRAY, result is undefined.
* Otherwise, there is no default.
Example: box.execute([[SELECT TYPEOF(LIKELY(?));]],{x}) is the name of one of the primitive data types.

SQL PLUS LUA – Adding Tarantool/NoSQL to Tarantool/SQL

The Adding Tarantool/NoSQL To Tarantool/SQL Guide contains descriptions of NoSQL database objects that can be accessed from SQL, of SQL database objects that can be accessed from NoSQL, of the way to call SQL from Lua, and of the way to call Lua from SQL.

Heading Введение
Lua requests Some Lua requests that are especially useful for SQL, such as requests to grant privileges
System tables Looking at Lua sysview spaces such as _space
Calling Lua routines from SQL Tarantool’s implementation of SQL stored procedures
Executing Lua chunks The LUA(…) function
Example sessions Million-row insert, etc.
Lua functions to make views of metadata Making equivalents to standard-SQL information_schema tables

Lua Requests

A great deal of functionality is not specifically part of Tarantool’s SQL feature, but is part of the Tarantool Lua application server and DBMS. Here are some examples so it is clear where to look in other sections of the Tarantool manual.

NoSQL «spaces» can be accessed as SQL "tables", and vice versa. For example, suppose a table has been created with
CREATE TABLE things (id INTEGER PRIMARY KEY, remark SCALAR);

This is viewable from Tarantool’s NoSQL feature as a memtx space named THINGS with a primary-key TREE index …

tarantool> box.space.THINGS
---
- engine: memtx
  before_replace: 'function: 0x40bb4608'
  on_replace: 'function: 0x40bb45e0'
  ck_constraint: []
  field_count: 2
  temporary: false
  index:
    0: &0
      unique: true
      parts:
     - type: integer
        is_nullable: false
        fieldno: 1
      id: 0
      space_id: 520
      type: TREE
      name: pk_unnamed_THINGS_1
    pk_unnamed_THINGS_1: *0
  is_local: false
  enabled: true
  name: THINGS
  id: 520

The NoSQL basic data operation requests select, insert, replace, upsert, update, delete will all work. Particularly interesting are the requests that come only via NoSQL.

To create an index on things (remark) with a non-default option for example a special id, say:
box.space.THINGS:create_index('idx_100_things_2', {id=100, parts={2, 'scalar'}})

(If the SQL data type name is SCALAR, then the NoSQL type is „scalar“, as described earlier. See the chart in section Operands.)

To grant database-access privileges to user „guest“, say
box.schema.user.grant('guest', 'execute', 'universe')
To grant SELECT privileges on table things to user „guest“, say
box.schema.user.grant('guest',  'read', 'space', 'THINGS')
To grant UPDATE privileges on table things to user „guest“, say:
box.schema.user.grant('guest', 'read,write', 'space', 'THINGS')
To grant DELETE or INSERT privileges on table things if no reading is involved, say:
box.schema.user.grant('guest', 'write', 'space', 'THINGS')
To grant DELETE or INSERT privileges on table things if reading is involved, say:
box.schema.user.grant('guest',  'read,write',  'space',  'THINGS')
To grant CREATE TABLE privilege to user „guest“, say
box.schema.user.grant('guest', 'read,write', 'space', '_schema')
box.schema.user.grant('guest', 'read,write', 'space', '_space')
box.schema.user.grant('guest', 'read,write', 'space', '_index')
box.schema.user.grant('guest', 'create', 'space')
To grant CREATE TRIGGER privilege to user „guest“, say
box.schema.user.grant('guest', 'read', 'space', '_space')
box.schema.user.grant('guest', 'read,write', 'space', '_trigger')
To grant CREATE INDEX privilege to user „guest“, say
box.schema.user.grant('guest', 'read,write', 'space', '_index')
box.schema.user.grant('guest', 'create', 'space')
To grant CREATE TABLE … INTEGER PRIMARY KEY AUTOINCREMENT to user „guest“, say
box.schema.user.grant('guest', 'read,write', 'space', '_schema')
box.schema.user.grant('guest', 'read,write', 'space', '_space')
box.schema.user.grant('guest', 'read,write', 'space', '_index')
box.schema.user.grant('guest', 'create', 'space')
box.schema.user.grant('guest', 'read,write', 'space', '_space_sequence')
box.schema.user.grant('guest', 'read,write', 'space', '_sequence')
box.schema.user.grant('guest', 'create', 'sequence')

To write a stored procedure that inserts 5 rows in things, say
function f() for i = 3, 7 do box.space.THINGS:insert{i, i} end end
For client-side API functions, see section «Connectors».

To make spaces with field names that SQL can understand, use space_object:format(). (Exception: in Tarantool/NoSQL it is legal for tuples to have more fields than are described by a format clause, but in Tarantool/SQL such fields will be ignored.)

To handle replication and sharding of SQL data, see section Sharding.

To enhance performance of SQL statements by preparing them in advance, see section box.prepare().

To call SQL from Lua, see section box.execute([[…]]).

Limitations: (Issue#2368)
* after box.schema.user.grant('guest','read,write,execute','universe'), user 'guest' can create tables. But this is a powerful set of privileges.

Limitations: (Issue#4659, Issue#4757, Issue#4758)
SELECT with * or ORDER BY or GROUP BY from spaces that have map fields or array fields may cause errors. Any access to spaces that have hash indexes may cause severe errors in Tarantool version 2.3 or earlier.

System Tables

There is a way to get some information about the database objects, for example the names of all the tables and their indexes, using SELECT statements. This is done by looking at special read-only tables which Tarantool updates automatically whenever objects are created or dropped. See the submodule box.space overview section. Names of system tables are in lower case so always enclose them in "quotes".

For example, the _space system table has these fields which are seen in SQL as columns:
  id = numeric identifier
  owner = for example, 1 if the object was made by the 'admin' user
  name = the name that was used with CREATE TABLE
  engine = usually 'memtx' (the 'vinyl' engine can be used but is not default)
  field_count = sometimes 0, but usually a count of the table’s columns
  flags = usually empty
  format = what a Lua format() function or an SQL CREATE statement produced
Example selection:
  SELECT "id", "name" FROM "_space";

See also: Lua functions to make views of metadata.

Calling Lua routines from SQL

SQL statements can invoke functions that are written in Lua. This is Tarantool’s equivalent for the «stored procedure» feature found in other SQL DBMSs. Tarantool server-side stored procedures are written in Lua rather than SQL/PSM dialect.

Functions can be invoked anywhere that the SQL syntax allows a literal or a column name for reading. Function parameters can include any number of SQL values. If a SELECT statement’s result set has a million rows, and the select list invokes a non-deterministic function, then the function is called a million times.

To create a Lua function that you can call from SQL, use box.schema.func.create(func-name, {options-with-body}) with these additional options:

exports = {'LUA', 'SQL'} – This indicates what languages can call the function. The default is 'LUA'. Specify both: 'LUA', 'SQL'.

param_list = {list} – This is the list of parameters. Specify the Lua type names for each parameter of the function. Remember that a Lua type name is the same as an SQL data type name, in lower case. The Lua type should not be an array.

Also it is good to specify {deterministic = true} if possible, because that may allow Tarantool to generate more efficient SQL byte code.

For a useful example, here is a general function for decoding a single Lua 'map' field:

box.schema.func.create('_DECODE',
   {language = 'LUA',
    returns = 'string',
    body = [[function (field, key)
             -- If Tarantool version < 2.10.1, replace next line with
             -- return require('msgpack').decode(field)[key]
             return field[key]
             end]],
    is_sandboxed = false,
    -- If Tarantool version < 2.10.1, replace next line with
    -- param_list = {'string', 'string'},
    param_list = {'map', 'string'},
    exports = {'LUA', 'SQL'},
    is_deterministic = true})

See it work with, say, the _trigger space. That space has a 'map' field named opts which has a key named sql. By selecting from the space and passing the field and the key name to _DECODE, you can get a list of all the trigger bodies.

box.execute([[SELECT _decode("opts", 'sql') FROM "_trigger";]])

Remember that SQL converts regular identifiers to upper case, so this example works with a function named _DECODE. If the function had been named _decode, then the SELECT statement would have to be:
box.execute([[SELECT "_decode"("opts", 'sql') FROM "_trigger";]])

Here is another example, which illustrates the way that Tarantool creates a view which includes the table_name and table_type columns in the same way that the standard-SQL information_schema.tables view contains them. The difficulty is that, in order to discover whether table_type should be 'BASE TABLE' or should be 'VIEW', it is necessary to know the value of the "flags" field in the Tarantool/NoSQL «_space» or "_vspace" space. The "flags" field type is "map", which SQL does not understand well. If there were no Lua functions, it would be necessary to treat the field as a VARBINARY and look for POSITION(X'A476696577C3',"flags")  > 0 (A4 is a MsgPack signal that a 4-byte string follows, 76696577 is UTF8 encoding for „view“, C3 is a MsgPack code meaning true). In any case, starting with Tarantool version 2.10, POSITION() does not work on VARBINARY operands. But there is a more sophisticated way, namely, creating a function that returns true if "flags".view is true. So for this case the way to make the function looks like this:

box.schema.func.create('TABLES_IS_VIEW',
     {language = 'LUA',
      returns = 'boolean',
      body = [[function (flags)
          local view
          -- If Tarantool version < 2.10.1, replace next line with
          -- view = require('msgpack').decode(flags).view
          view = flags.view
          if view == nil then return false end
          return view
          end]],
     is_sandboxed = false,
     -- If Tarantool version < 2.10.1, replace next line with
     -- param_list = {'string'},
     param_list = {'map'},
     exports = {'LUA', 'SQL'},
     is_deterministic = true})

And this creates the view:

box.execute([[
CREATE VIEW vtables AS SELECT
"name" AS table_name,
CASE WHEN tables_is_view("flags") == TRUE THEN 'VIEW'
     ELSE 'BASE TABLE' END AS table_type,
"id" AS id,
"engine" AS engine,
(SELECT "name" FROM "_vuser" x
 WHERE x."id" = y."owner") AS owner,
"field_count" AS field_count
FROM "_vspace" y;
]])

Remember that these Lua functions are persistent, so if the server has to be restarted then they do not have to be re-declared.

Executing Lua chunks

To execute Lua code without creating a function, use:
LUA(Lua-code-string)
where Lua-code-string is any amount of Lua code. The string should begin with 'return '.

For example this will show the number of seconds since the epoch:
box.execute([[SELECT lua('return os.time()');]])
For example this will show a database configuration member:
box.execute([[SELECT lua('return box.cfg.memtx_memory');]])
For example this will return FALSE because Lua nil and box.NULL are the same as SQL NULL:
box.execute([[SELECT lua('return box.NULL') IS NOT NULL;]])

Warning: the SQL statement must not invoke a Lua function, or execute a Lua chunk, that accesses a space that underlies any SQL table that the SQL statement accesses. For example, if function f() contains a request "box.space.TEST:insert{0}", then the SQL statement "SELECT f() FROM test;" will try to access the same space in two ways. The results of such conflict may include a hang or an infinite loop.

Example Sessions

Example Session – Create, Insert, Select

Assume that the task is to create two tables, put some rows in each table, create a view that is based on a join of the tables, then select from the view all rows where the second column values are not null, ordered by the first column.

That is, the way to populate the table is
CREATE TABLE t1 (c1 INTEGER PRIMARY KEY, c2 STRING);
CREATE TABLE t2 (c1 INTEGER PRIMARY KEY, x2 STRING);
INSERT INTO t1 VALUES (1, 'A'), (2, 'B'), (3, 'C');
INSERT INTO t1 VALUES (4, 'D'), (5, 'E'), (6, 'F');
INSERT INTO t2 VALUES (1, 'C'), (4, 'A'), (6, NULL);
CREATE VIEW v AS SELECT * FROM t1 NATURAL JOIN t2;
SELECT * FROM v WHERE c2 IS NOT NULL ORDER BY c1;

So the session looks like this:
box.cfg{}
box.execute([[CREATE TABLE t1 (c1 INTEGER PRIMARY KEY, c2 STRING);]])
box.execute([[CREATE TABLE t2 (c1 INTEGER PRIMARY KEY, x2 STRING);]])
box.execute([[INSERT INTO t1 VALUES (1, 'A'), (2, 'B'), (3, 'C');]])
box.execute([[INSERT INTO t1 VALUES (4, 'D'), (5, 'E'), (6, 'F');]])
box.execute([[INSERT INTO t2 VALUES (1, 'C'), (4, 'A'), (6, NULL);]])
box.execute([[CREATE VIEW v AS SELECT * FROM t1 NATURAL JOIN t2;]])
box.execute([[SELECT * FROM v WHERE c2 IS NOT NULL ORDER BY c1;]])

If one executes the above requests with Tarantool as a client, provided the database objects do not already exist, the execution will be successful and the final display will be

tarantool> box.execute([[SELECT * FROM v WHERE c2 IS NOT NULL ORDER BY c1;]])
---
- - [1, 'A', 'C']
- [4, 'D', 'A']
- [6, 'F', null]

Example Session – Get a List of Columns

Here is a function which will create a table that contains a list of all the columns and their Lua types, for all tables. It is not a necessary function because one can create a _COLUMNS view instead. It merely shows, with simpler Lua code, how to make a base table instead of a view.

function create_information_schema_columns()
  box.execute([[DROP TABLE IF EXISTS information_schema_columns;]])
  box.execute([[CREATE TABLE information_schema_columns (
                    table_name STRING,
                    column_name STRING,
                    ordinal_position INTEGER,
                    data_type STRING,
                    PRIMARY KEY (table_name, column_name));]]);
  local space = box.space._vspace:select()
  local sqlstring = ''
  for i = 1, #space do
      for j = 1, #space[i][7] do
          sqlstring = "INSERT INTO information_schema_columns VALUES ("
                  .. "'" .. space[i][3] .. "'"
                  .. ","
                  .. "'" .. space[i][7][j].name .. "'"
                  .. ","
                  .. j
                  .. ","
                  .. "'" .. space[i][7][j].type .. "'"
                  .. ");"
          box.execute(sqlstring)
      end
  end
  return
end

If you now execute the function by saying
create_information_schema_columns()
you will see that there is a table named information_schema_columns containing table_name and column_name and ordinal_position and data_type for everything that was accessible.

Example Session – Million-Row Insert

Here is a variation of the Lua tutorial «Insert one million tuples with a Lua stored procedure». The differences are: the creation is done with an SQL CREATE TABLE statement, and the inserting is done with an SQL INSERT statement. Otherwise, it is the same. It is the same because Lua and SQL are compatible, just as Lua and NoSQL are compatible.

box.execute([[CREATE TABLE tester (s1 INTEGER PRIMARY KEY, s2 STRING);]])

function string_function()
  local random_number
  local random_string
  random_string = ""
  for x = 1,10,1 do
    random_number = math.random(65, 90)
    random_string = random_string .. string.char(random_number)
  end
  return random_string
end

function main_function()
    local string_value, t, sql_statement
    for i = 1,1000000, 1 do
    string_value = string_function()
    sql_statement = "INSERT INTO tester VALUES (" .. i .. ",'" .. string_value .. "');"
    box.execute(sql_statement)
    end
end
start_time = os.clock()
main_function()
end_time = os.clock()
'insert done in ' .. end_time - start_time .. ' seconds'

Limitations: The function takes more time than the original (Tarantool/NoSQL).

Lua functions to make views of metadata

Tarantool does not include all the standard-SQL information_schema views, which are for looking at metadata, that is, «data about the data». But here is the Lua code and SQL code for creating equivalents:
_TABLES nearly equivalent to INFORMATION_SCHEMA.TABLES
_COLUMNS nearly equivalent to INFORMATION_SCHEMA.COLUMNS
_VIEWS nearly equivalent to INFORMATION_SCHEMA.VIEWS
_TRIGGERS nearly equivalent to INFORMATION_SCHEMA.TRIGGERS
_REFERENTIAL_CONSTRAINTS nearly equivalent to INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS
_CHECK_CONSTRAINTS nearly equivalent to INFORMATION_SCHEMA.CHECK_CONSTRAINTS
_TABLE_CONSTRAINTS nearly equivalent to INFORMATION_SCHEMA.TABLE_CONSTRAINTS.
For each view there will be an example of a SELECT from the view, and the code. Users who want metadata can simply copy the code. Use this code only with Tarantool version 2.3.0 or later. With an earlier Tarantool version, a PRAGMA statement may be useful.

_TABLES view

Пример:

tarantool>SELECT * FROM _tables WHERE id > 340 LIMIT 5;
OK 5 rows selected (0.0 seconds)
+---------------+--------------+----------------+------------+-----+--------+-------+-------------+
| TABLE_CATALOG | TABLE_SCHEMA | TABLE_NAME     | TABLE_TYPE | ID  | ENGINE | OWNER | FIELD_COUNT |
+---------------+--------------+----------------+------------+-----+--------+-------+-------------+
| NULL          | NULL         | _fk_constraint | BASE TABLE | 356 | memtx  | admin |        0    |
| NULL          | NULL         | _ck_constraint | BASE TABLE | 364 | memtx  | admin |        0    |
| NULL          | NULL         | _func_index    | BASE TABLE | 372 | memtx  | admin |        0    |
| NULL          | NULL         | _COLUMNS       | VIEW       | 513 | memtx  | admin |        8    |
| NULL          | NULL         | _VIEWS         | VIEW       | 514 | memtx  | admin |        7    |
+---------------+--------------+----------------+------------+-----+--------+-------+-------------+

Definition of the function and the CREATE VIEW statement:

box.schema.func.drop('_TABLES_IS_VIEW',{if_exists = true})
box.schema.func.create('_TABLES_IS_VIEW',
     {language = 'LUA',
      returns = 'boolean',
      body = [[function (flags)
          local view
          -- If Tarantool version < 2.10.1, replace next line with
          -- view = require('msgpack').decode(flags).view
          view = flags.view
          if view == nil then return false end
          return view
          end]],
     is_sandboxed = false,
     -- If Tarantool version < 2.10.1, replace next line with
     -- param_list = {'string'},
     param_list = {'map'},
     exports = {'LUA', 'SQL'},
     is_deterministic = true})
box.schema.role.grant('public', 'execute', 'function', '_TABLES_IS_VIEW')
pcall(function ()
    box.schema.role.revoke('public', 'read', 'space', '_TABLES', {if_exists = true})
    end)
box.execute([[DROP VIEW IF EXISTS _tables;]])
box.execute([[
CREATE VIEW _tables AS SELECT
    CAST(NULL AS STRING) AS table_catalog,
    CAST(NULL AS STRING) AS table_schema,
    "name" AS table_name,
    CASE
        WHEN _tables_is_view("flags") = TRUE THEN 'VIEW'
        ELSE 'BASE TABLE' END
        AS table_type,
    "id" AS id,
    "engine" AS engine,
    (SELECT "name" FROM "_vuser" x WHERE x."id" = y."owner") AS owner,
    "field_count" AS field_count
FROM "_vspace" y;
]])
box.schema.role.grant('public', 'read', 'space', '_TABLES')

_COLUMNS view

Этот пример также показывает, как с помощью рекурсивных представлений создавать временные таблицы с несколькими строками для каждого кортежа в исходном спейсе "_vspace". Для этого потребуется глобальная переменная _G.box.FORMATS в качестве временной статической переменной.

Warning: Use this code only with Tarantool version 2.3.2 or later. Use with earlier versions will cause an assertion. See Issue#4504.

Пример:

tarantool>SELECT * FROM _columns WHERE ordinal_position = 9;
OK 6 rows selected (0.0 seconds)
+--------------+-------------+--------------------------+--------------+------------------+-------------+-----------+-----+
| CATALOG_NAME | SCHEMA_NAME | TABLE_NAME               | COLUMN_NAME  | ORDINAL_POSITION | IS_NULLABLE | DATA_TYPE | ID  |
+--------------+-------------+--------------------------+--------------+------------------+-------------+-----------+-----+
| NULL         | NULL        | _sequence                | cycle        |                9 | YES         | boolean   | 284 |
| NULL         | NULL        | _vsequence               | cycle        |                9 | YES         | boolean   | 286 |
| NULL         | NULL        | _func                    | returns      |                9   YES           string    | 296 |
| NULL         | NULL        | _fk_constraint           | parent_cols  |                9 | YES         | array     | 356 |
| NULL         | NULL        | _REFERENTIAL_CONSTRAINTS | MATCH_OPTION |                9 | YES         | string    | 518 |
+--------------+-------------+--------------------------+--------------+------------------+-------------+-----------+-----+

Definition of the function and the CREATE VIEW statement:

box.schema.func.drop('_COLUMNS_FORMATS', {if_exists = true})
box.schema.func.create('_COLUMNS_FORMATS',
    {language = 'LUA',
     returns = 'scalar',
     body = [[
     function (row_number_, ordinal_position)
         if row_number_ == 0 then
             _G.box.FORMATS = {}
             local vspace = box.space._vspace:select()
             for i = 1, #vspace do
                 local format = vspace[i]["format"]
                 for j = 1, #format do
                     local is_nullable = 'YES'
                     if format[j].is_nullable == false then
                         is_nullable = 'NO'
                     end
                     table.insert(_G.box.FORMATS,
                                  {vspace[i].name, format[j].name, j,
                                   is_nullable, format[j].type, vspace[i].id})
                 end
             end
             return ''
         end
         if row_number_ > #_G.box.FORMATS then
             _G.box.FORMATS = {}
             return ''
         end
         return _G.box.FORMATS[row_number_][ordinal_position]
     end
     ]],
    param_list = {'integer', 'integer'},
    exports = {'LUA', 'SQL'},
    is_sandboxed = false,
    setuid = false,
    is_deterministic = false})
box.schema.role.grant('public', 'execute', 'function', '_COLUMNS_FORMATS')

pcall(function ()
    box.schema.role.revoke('public', 'read', 'space', '_COLUMNS', {if_exists = true})
    end)
box.execute([[DROP VIEW IF EXISTS _columns;]])
box.execute([[
CREATE VIEW _columns AS
WITH RECURSIVE r_columns AS
(
SELECT 0 AS row_number_,
      '' AS table_name,
      '' AS column_name,
      0 AS ordinal_position,
      '' AS is_nullable,
      '' AS data_type,
      0 AS id
UNION ALL
SELECT row_number_ + 1 AS row_number_,
       _columns_formats(row_number_, 1) AS table_name,
       _columns_formats(row_number_, 2) AS column_name,
       _columns_formats(row_number_, 3) AS ordinal_position,
       _columns_formats(row_number_, 4) AS is_nullable,
       _columns_formats(row_number_, 5) AS data_type,
       _columns_formats(row_number_, 6) AS id
    FROM r_columns
    WHERE row_number_ == 0 OR row_number_ <= lua('return #_G.box.FORMATS + 1')
)
SELECT CAST(NULL AS STRING) AS catalog_name,
       CAST(NULL AS STRING) AS schema_name,
       table_name,
       column_name,
       ordinal_position,
       is_nullable,
       data_type,
       id
    FROM r_columns
    WHERE data_type <> '';
]])
box.schema.role.grant('public', 'read', 'space', '_COLUMNS')

_VIEWS view

Пример:

tarantool>SELECT table_name, substr(view_definition,1,20), id, owner, field_count FROM _views LIMIT 5;
OK 5 rows selected (0.0 seconds)
+--------------------------+------------------------------+-----+-------+-------------+
| TABLE_NAME               | SUBSTR(VIEW_DEFINITION,1,20) | ID  | OWNER | FIELD_COUNT |
+--------------------------+------------------------------+-----+-------+-------------+
| _COLUMNS                 | CREATE VIEW _columns         | 513 | admin |           8 |
| _TRIGGERS                | CREATE VIEW _trigger         | 515 | admin |           4 |
| _CHECK_CONSTRAINTS       | CREATE VIEW _check_c         | 517 | admin |           8 |
| _REFERENTIAL_CONSTRAINTS | CREATE VIEW _referen         | 518 | admin |          12 |
| _TABLE_CONSTRAINTS       | CREATE VIEW _table_c         | 519 | admin |          11 |
+--------------------------+------------------------------+-----+-------+-------------+

Definition of the function and the CREATE VIEW statement:

box.schema.func.drop('_VIEWS_DEFINITION',{if_exists = true})
box.schema.func.create('_VIEWS_DEFINITION',
    {language = 'LUA',
     returns = 'string',
     body = [[function (flags)
              -- If Tarantool version < 2.10.1, replace next line with
              -- return require('msgpack').decode(flags).sql
              return flags.sql
              end]],
     -- If Tarantool version < 2.10.1, replace next line with
     -- param_list = {'string'},
     param_list = {'map'},
     exports = {'LUA', 'SQL'},
     is_sandboxed = false,
     setuid = false,
     is_deterministic = false})
box.schema.role.grant('public', 'execute', 'function', '_VIEWS_DEFINITION')
pcall(function ()
    box.schema.role.revoke('public', 'read', 'space', '_VIEWS', {if_exists = true})
    end)
box.execute([[DROP VIEW IF EXISTS _views;]])
box.execute([[
CREATE VIEW _views AS SELECT
    CAST(NULL AS STRING) AS table_catalog,
    CAST(NULL AS STRING) AS table_schema,
    "name" AS table_name,
    CAST(_views_definition("flags") AS STRING) AS VIEW_DEFINITION,
    "id" AS id,
    (SELECT "name" FROM "_vuser" x WHERE x."id" = y."owner") AS owner,
    "field_count" AS field_count
    FROM "_vspace" y
    WHERE _tables_is_view("flags") = TRUE;
]])
box.schema.role.grant('public', 'read', 'space', '_VIEWS')

_TABLES_IS_VIEW() was described earlier, see _TABLES view.

_TRIGGERS view

Пример:

tarantool>SELECT trigger_name, opts_sql FROM _triggers;
OK 2 rows selected (0.0 seconds)
+--------------+-------------------------------------------------------------------------------------------------+
| TRIGGER_NAME | OPTS_SQL                                                                                        |
+--------------+-------------------------------------------------------------------------------------------------+
| THINGS1_AD   | CREATE TRIGGER things1_ad AFTER DELETE ON things1 FOR EACH ROW BEGIN DELETE FROM things2; END;  |
| THINGS1_BI   | CREATE TRIGGER things1_bi BEFORE INSERT ON things1 FOR EACH ROW BEGIN DELETE FROM things2; END; |
+--------------+-------------------------------------------------------------------------------------------------+

Definition of the function and the CREATE VIEW statement:

box.schema.func.drop('_TRIGGERS_OPTS_SQL',{if_exists = true})
box.schema.func.create('_TRIGGERS_OPTS_SQL',
    {language = 'LUA',
     returns = 'string',
     body = [[function (opts)
              -- If Tarantool version < 2.10.1, replace next line with
              -- return require('msgpack').decode(opts).sql
              return opts.sql
              end]],
     -- If Tarantool version < 2.10.1, replace next line with
     -- param_list = {'string'},
     param_list = {'map'},
     exports = {'LUA', 'SQL'},
     is_sandboxed = false,
     setuid = false,
     is_deterministic = false})
box.schema.role.grant('public', 'execute', 'function', '_TRIGGERS_OPTS_SQL')
pcall(function ()
    box.schema.role.revoke('public', 'read', 'space', '_TRIGGERS', {if_exists = true})
    end)
box.execute([[DROP VIEW IF EXISTS _triggers;]])
box.execute([[
CREATE VIEW _triggers AS SELECT
    CAST(NULL AS STRING) AS trigger_catalog,
    CAST(NULL AS STRING) AS trigger_schema,
    "name" AS trigger_name,
    CAST(_triggers_opts_sql("opts") AS STRING) AS opts_sql,
    "space_id" AS space_id
    FROM "_trigger";
]])
box.schema.role.grant('public', 'read', 'space', '_TRIGGERS')

Users who select from this view will need „read“ privilege on the _trigger space.

_REFERENTIAL_CONSTRAINTS view

Пример:

tarantool>SELECT constraint_name, update_rule, delete_rule, match_option,
> referencing, referenced
> FROM _referential_constraints;
OK 2 rows selected (0.0 seconds)
+----------------------+-------------+-------------+--------------+-------------+------------+
| CONSTRAINT_NAME      | UPDATE_RULE | DELETE_RULE | MATCH_OPTION | REFERENCING | REFERENCED |
+----------------------+-------------+-------------+--------------+-------------+------------+
| fk_unnamed_THINGS2_1 | no_action   | no_action   | simple       | THINGS2     | THINGS1    |
| fk_unnamed_THINGS3_1 | no_action   | no_action   | simple       | THINGS3     | THINGS1    |
+----------------------+-------------+-------------+--------------+-------------+------------+

Definition of the CREATE VIEW statement:

pcall(function ()
    box.schema.role.revoke('public', 'read', 'space', '_REFERENTIAL_CONSTRAINTS', {if_exists = true})
    end)
box.execute([[DROP VIEW IF EXISTS _referential_constraints;]])
box.execute([[
CREATE VIEW _referential_constraints AS SELECT
    CAST(NULL AS STRING) AS constraint_catalog,
    CAST(NULL AS STRING) AS constraint_schema,
    "name" AS constraint_name,
    CAST(NULL AS STRING) AS unique_constraint_catalog,
    CAST(NULL AS STRING) AS unique_constraint_schema,
    '' AS unique_constraint_name,
    "on_update" AS update_rule,
    "on_delete" AS delete_rule,
    "match" AS match_option,
    (SELECT "name" FROM "_vspace" x WHERE x."id" = y."child_id") AS referencing,
    (SELECT "name" FROM "_vspace" x WHERE x."id" = y."parent_id") AS referenced,
    "is_deferred" AS is_deferred,
    "child_id" AS child_id,
    "parent_id" AS parent_id
    FROM "_fk_constraint" y;
]])
box.schema.role.grant('public', 'read', 'space', '_REFERENTIAL_CONSTRAINTS')

In this example child_cols or parent_cols are not taken from the _fk_constraint space because in standard SQL those are in a separate table.

Users who select from this view will need „read“ privilege on the _fk_constraint space.

_CHECK_CONSTRAINTS view

Пример:

tarantool>SELECT constraint_name, check_clause, space_name, language
> FROM _check_constraints;
OK 3 rows selected (0.0 seconds)
+------------------------+-------------------------+------------+----------+
| CONSTRAINT_NAME        | CHECK_CLAUSE            | SPACE_NAME | LANGUAGE |
+------------------------+-------------------------+------------+----------+
| ck_unnamed_Employees_1 | first_name LIKE 'Влад%' | Employees  | SQL      |
| ck_unnamed_Critics_1   | first_name LIKE 'Vlad%' | Critics    | SQL      |
| ck_unnamed_ACTORS_1    | salary > 0              | ACTORS     | SQL      |
+------------------------+-------------------------+------------+----------+

Definition of the CREATE VIEW statement:

pcall(function ()
    box.schema.role.revoke('public', 'read', 'space', '_CHECK_CONSTRAINTS', {if_exists = true})
    end)
box.execute([[DROP VIEW IF EXISTS _check_constraints;]])
box.execute([[
CREATE VIEW _check_constraints AS SELECT
    CAST(NULL AS STRING) AS constraint_catalog,
    CAST(NULL AS STRING) AS constraint_schema,
    "name" AS constraint_name,
    "code" AS check_clause,
    (SELECT "name" FROM "_vspace" x WHERE x."id" = y."space_id") AS space_name,
    "language" AS language,
    "is_deferred" AS is_deferred,
    "space_id" AS space_id
    FROM "_ck_constraint" y;
]])
box.schema.role.grant('public', 'read', 'space', '_CHECK_CONSTRAINTS')

Users who select from this view will need „read“ privilege on the _ck_constraint space.

_TABLE_CONSTRAINTS view

This has only the constraints (primary-key and unique-key) that can be found by looking at the _index space. It is not a list of indexes, that is, it is not equivalent to INFORMATION_SCHEMA.STATISTICS. The columns of the index are not taken because in standard SQL they would be in a different table.

Пример:

tarantool>SELECT constraint_name, constraint_type, table_name, id, iid, index_type
> FROM _table_constraints
> LIMIT 5;
OK 5 rows selected (0.0 seconds)
+-----------------+-----------------+-------------+-----+-----+------------+
| CONSTRAINT_NAME | CONSTRAINT_TYPE | TABLE_NAME  | ID  | IID | INDEX_TYPE |
+-----------------+-----------------+-------------+-----+-----+------------+
| primary         | PRIMARY         | _schema     | 272 |   0 | tree       |
| primary         | PRIMARY         | _collation  | 276 |   0 | tree       |
| name            | UNIQUE          | _collation  | 276 |   1 | tree       |
| primary         | PRIMARY         | _vcollation | 277 |   0 | tree       |
| name            | UNIQUE          | _vcollation | 277 |   1 | tree       |
+-----------------+-----------------+-------------+-----+-----+------------+

Definition of the function and the CREATE VIEW statement:

box.schema.func.drop('_TABLE_CONSTRAINTS_OPTS_UNIQUE',{if_exists = true})
function _TABLE_CONSTRAINTS_OPTS_UNIQUE (opts) return require('msgpack').decode(opts).unique end
box.schema.func.create('_TABLE_CONSTRAINTS_OPTS_UNIQUE',
    {language = 'LUA',
     returns = 'boolean',
     body = [[function (opts) return require('msgpack').decode(opts).unique end]],
     param_list = {'string'},
     exports = {'LUA', 'SQL'},
     is_sandboxed = false,
     setuid = false,
     is_deterministic = false})
box.schema.role.grant('public', 'execute', 'function', '_TABLE_CONSTRAINTS_OPTS_UNIQUE')
pcall(function ()
box.schema.role.revoke('public', 'read', 'space', '_TABLE_CONSTRAINTS', {if_exists = true})
end)
box.execute([[DROP VIEW IF EXISTS _table_constraints;]])
box.execute([[
CREATE VIEW _table_constraints AS SELECT
CAST(NULL AS STRING) AS constraint_catalog,
CAST(NULL AS STRING) AS constraint_schema,
"name" AS constraint_name,
(SELECT "name" FROM "_vspace" x WHERE x."id" = y."id") AS table_name,
CASE WHEN "iid" = 0 THEN 'PRIMARY' ELSE 'UNIQUE' END AS constraint_type,
CAST(NULL AS STRING) AS initially_deferrable,
CAST(NULL AS STRING) AS deferred,
CAST(NULL AS STRING) AS enforced,
"id" AS id,
"iid" AS iid,
"type" AS index_type
FROM "_vindex" y
WHERE _table_constraints_opts_unique("opts") = TRUE;
]])
box.schema.role.grant('public', 'read', 'space', '_TABLE_CONSTRAINTS')

Возможности SQL

This section compares Tarantool’s features with SQL:2016’s «Feature taxonomy and definition for mandatory features».

For each feature in that list, there will be a simple example SQL statement. If Tarantool appears to handle the example, it will be marked «Okay», else it will be marked «Fail». Since this is rough and arbitrary, the hope is that tests which are unfairly marked «Okay» will probably be balanced by tests which are unfairly marked «Fail».

E011, числовые типы данных

Код возможности Возможность Пример Результаты тестов
E011-01 Типы данных INTEGER и SMALLINT CREATE TABLE t (s1 INT PRIMARY KEY); Работает.
E011-02 Типы данных REAL, DOUBLE PRECISION и FLOAT CREATE TABLE tr (s1 FLOAT PRIMARY KEY); Ошибка. Тип данных с плавающей точкой в Tarantool — DOUBLE. Примечание: Скорее всего, типы с плавающей точкой в версиях 2.1 и 2.2 не будут совместимы: в версии 2.1 для столбцов этих типов задается формат „number“, а в версии 2.2 — „float32“ и „float64“. Для смены формата требуется перенос данных, который не выполняется автоматически, поскольку в версии 2.1 нет информации, как отличать столбцы „number“, созданные через Lua, от FLOAT/DOUBLE/REAL, созданных через SQL.
E011-03 Типы данных DECIMAL и NUMERIC CREATE TABLE td (s1 NUMERIC PRIMARY KEY); Fail, NUMERIC data types are not supported, although the DECIMAL data type is supported.
E011-04 Арифметические операторы SELECT 10+1, 9-2, 8*3, 7/2 FROM t; Работает.
E011-05 Числовые сравнения SELECT * FROM t WHERE 1 < 2; Работает.
E011-06 Неявное приведение числовых типов данных SELECT * FROM t WHERE s1 = 1.00; Работает, потому что Tarantool поддерживает сравнение 1.00 с INTEGER.

E021, типы символьных строк

Код возможности Возможность Пример Результаты тестов
E021-01 Символьный тип данных (включая все варианты написания) CREATE TABLE t44 (s1 CHAR PRIMARY KEY); Ошибка, тип данных CHAR не поддерживается. Этот тип ошибки будет учитываться только один раз.
E021-02 Тип данных CHARACTER VARYING (включая все варианты написания) CREATE TABLE t45 (s1 VARCHAR PRIMARY KEY); Ошибка, Tarantool поддерживает только VARCHAR(n), являющийся синонимом STRING.
E021-03 Символьные литералы INSERT INTO t45 VALUES (''); Работает. Кроме того, избегается нежелательная практика принятия "" за символьные литералы.
E021-04 Функция CHARACTER_LENGTH SELECT character_length(s1) FROM t; Работает. Tarantool воспринимает эту функцию как синоним LENGTH().
E021-05 OCTET_LENGTH SELECT octet_length(s1) FROM t; Ошибка. Такой функции нет.
E021-06 Функция SUBSTRING SELECT substring(s1 FROM 1 FOR 1) FROM t; Ошибка, такой функции нет. Есть функция SUBSTR(x,n,n).
E021-07 Конкатенация символов SELECT 'a' || 'b' FROM t; Работает.
E021-08 Функции UPPER и LOWER SELECT upper('a'),lower('B') FROM t; Работает. Tarantool поддерживает как UPPER(), так и LOWER().
E021-09 Функция TRIM SELECT trim('a ') FROM t; Работает.
E021-10 Неявное приведение типов символьных строк фиксированной и переменной длины SELECT * FROM tm WHERE char_column > varchar_column; Ошибка, тип символьной строки фиксированной длины отсутствует.
E021-11 Функция POSITION SELECT position(x IN y) FROM z; Ошибка. В функции Tarantool POSITION используется „,“, а не „IN“.
E021-12 Сравнение символов SELECT * FROM t WHERE s1 > 'a'; Работает. Стоит отметить, что в сравнениях по умолчанию используется двоичная сортировка, но можно использовать и COLLATE.

E031, идентификаторы

Код возможности Возможность Пример Результаты тестов
E031 Идентификаторы CREATE TABLE rank (ceil INT PRIMARY KEY); Ошибка. Список зарезервированных слов в Tarantool отличается от стандартного.
E031-01 Идентификаторы с разделителем CREATE TABLE "t47" (s1 INT PRIMARY KEY); Работает. Кроме того, заключение идентификаторов в двойные кавычки означает, что они не будут приводиться к верхнему или нижнему регистру. В некоторых других СУБД эта особенность отсутствует.
E031-02 Идентификаторы в нижнем регистре CREATE TABLE t48 (s1 INT PRIMARY KEY); Работает.
E031-03 Символ нижнего подчеркивания в конце CREATE TABLE t49_ (s1 INT PRIMARY KEY); Работает.

E051, базовые запросы

Код возможности Возможность Пример Результаты тестов
E051-01 SELECT DISTINCT SELECT DISTINCT s1 FROM t; Работает.
E051-02 Предложение GROUP BY SELECT DISTINCT s1 FROM t GROUP BY s1; Работает.
E051-04 GROUP BY может содержать столбцы вне выборки SELECT SELECT s1 FROM t GROUP BY lower(s1); Работает.
E051-05 Элементы в списке выборки можно переименовывать SELECT s1 AS K FROM t ORDER BY K; Работает.
E051-06 Предложение HAVING SELECT count(*) FROM t HAVING count(*) > 0; Работает. Tarantool поддерживает HAVING, при этом GROUP BY перед HAVING не является обязательным.
E051-07 Допускается использование * в квалификаторе для списка выборки SELECT t.* FROM t; Работает.
E051-08 Корреляционные имена в предложении FROM SELECT * FROM t AS K; Работает.
E051-09 Переименование столбцов в предложении FROM SELECT * FROM t AS x(q,c); Ошибка.

E061, базовые предикаты и условия поиска

Код возможности Возможность Пример Результаты тестов
E061-01 Предикат сравнения SELECT * FROM t WHERE 0 = 0; Работает.
E061-02 Предикат BETWEEN SELECT * FROM t WHERE ' ' BETWEEN '' AND ' '; Работает.
E061-03 Предикат IN со списком значений SELECT * FROM t WHERE s1 IN ('a', upper('a')); Работает.
E061-04 Предикат LIKE SELECT * FROM t WHERE s1 LIKE '_'; Работает.
E061-05 Предикат LIKE: предложение ESCAPE VALUES ('abc_' LIKE 'abcX_' ESCAPE 'X'); Работает.
E061-06 Предикат NULL SELECT * FROM t WHERE s1 IS NOT NULL; Работает.
E061-07 Предикат количественного сравнения SELECT * FROM t WHERE s1 = ANY (SELECT s1 FROM t); Ошибка — в синтаксисе.
E061-08 Предикат EXISTS SELECT * FROM t WHERE NOT EXISTS (SELECT * FROM t); Работает.
E061-09 Подзапросы в предикате сравнения SELECT * FROM t WHERE s1 > (SELECT s1 FROM t); Работает.
E061-11 Подзапросы в предикате IN SELECT * FROM t WHERE s1 IN (SELECT s1 FROM t); Работает.
E061-12 Подзапросы в предикате количественного сравнения SELECT * FROM t WHERE s1 >= ALL (SELECT s1 FROM t); Ошибка — в синтаксисе.
E061-13 Коррелирующие подзапросы SELECT * FROM t WHERE s1 = (SELECT s1 FROM t2 WHERE t2.s2 = t.s1); Работает.
E061-14 Условие поиска SELECT * FROM t WHERE 0 <> 0 OR 'a' < 'b' AND s1 IS NULL; Работает.

E071, базовые выражения с запросами

Код возможности Возможность Пример Результаты тестов
E071-01 Табличный оператор UNION DISTINCT SELECT * FROM t UNION DISTINCT SELECT * FROM t; Ошибка. Однако SELECT * FROM t UNION SELECT * FROM t; работает.
E071-02 Табличный оператор UNION ALL SELECT * FROM t UNION ALL SELECT * FROM t; Работает.
E071-03 Табличный оператор EXCEPT DISTINCT SELECT * FROM t EXCEPT DISTINCT SELECT * FROM t; Ошибка. Однако SELECT * FROM t EXCEPT SELECT * FROM t; работает.
E071-05 Столбцы, совмещенные с помощью табличных операторов, необязательно должны иметь идентичный тип данных SELECT s1 FROM t UNION SELECT 5 FROM t; Работает.
E071-06 Табличные операторы в подзапросах SELECT * FROM t WHERE 'a' IN (SELECT * FROM t UNION SELECT * FROM t); Работает.

E081, базовые права

Tarantool не поддерживает права, кроме как через NoSQL.

E091, агрегатные функции

Код возможности Возможность Пример Результаты тестов
E091-01 AVG SELECT avg(s1) FROM t7; Ошибка. Tarantool поддерживает AVG, но предупреждение об исключении NULL отсутствует.
E091-02 COUNT SELECT count(*) FROM t7 WHERE s1 > 0; Работает.
E091-03 MAX SELECT max(s1) FROM t7 WHERE s1 > 0; Работает.
E091-04 MIN SELECT min(s1) FROM t7 WHERE s1 > 0; Работает.
E091-05 SUM SELECT sum(1) FROM t7 WHERE s1 > 0; Работает.
E091-06 Квантификатор ALL SELECT sum(ALL s1) FROM t7 WHERE s1 > 0; Работает.
E091-07 Квантификатор DISTINCT SELECT sum(DISTINCT s1) FROM t7 WHERE s1 > 0; Работает.

E101, базовая обработка данных

Код возможности Возможность Пример Результаты тестов
E101-01 Инструкция INSERT INSERT INTO t (s1,s2) VALUES (1,''), (2,NULL), (3,55); Работает.
E101-03 Инструкция UPDATE с поиском UPDATE t SET s1 = NULL WHERE s1 IN (SELECT s1 FROM t2); Работает.
E101-04 Инструкция DELETE с поиском DELETE FROM t WHERE s1 IN (SELECT s1 FROM t); Работает.

E111, инструкция SELECT, возвращающая одну строку

Код возможности Возможность Пример Результаты тестов
E111 Инструкция SELECT, возвращающая одну строку SELECT count(*) FROM t; Работает.

E121, базовая поддержка курсоров

Код возможности Возможность Пример Результаты тестов
E121-01 DECLARE CURSOR   Ошибка. Tarantool не поддерживает курсоры.
E121-02 Столбцы ORDER BY необязательно должны быть в списке выборки SELECT s1 FROM t ORDER BY s2; Работает.
E121-03 Выражения в ORDER BY SELECT s1 FROM t7 ORDER BY -s1; Работает.
E121-04 Инструкция OPEN   Ошибка. Tarantool не поддерживает курсоры.
E121-06 Инструкция UPDATE с позицией   Ошибка. Tarantool не поддерживает курсоры.
E121-07 Инструкция DELETE с позицией   Ошибка. Tarantool не поддерживает курсоры.
E121-08 Инструкция CLOSE   Ошибка. Tarantool не поддерживает курсоры.
E121-10 Инструкция FETCH с неявным NEXT   Ошибка. Tarantool не поддерживает курсоры.
E121-17 Курсоры WITH HOLD   Ошибка. Tarantool не поддерживает курсоры.

E131, поддержка значения Null

Код возможности Возможность Пример Результаты тестов
E131 Поддержка значения NULL (NULL вместо значений) SELECT s1 FROM t7 WHERE s1 IS NULL; Работает.

E141, базовые ограничения целостности

Код возможности Возможность Пример Результаты тестов
E141-01 Ограничения NOT NULL CREATE TABLE t8 (s1 INT PRIMARY KEY, s2 INT NOT NULL); Работает.
E141-02 Ограничения UNIQUE для столбцов NOT NULL CREATE TABLE t9 (s1 INT PRIMARY KEY , s2 INT NOT NULL UNIQUE); Работает.
E141-03 Ограничения PRIMARY KEY CREATE TABLE t10 (s1 INT PRIMARY KEY); Работает, хотя в Tarantool необязательно наличие первичного ключа.
E141-04 Базовое ограничение FOREIGN KEY без действия (NO ACTION) по умолчанию для операций удаления и изменения со ссылками CREATE TABLE t11 (s0 INT PRIMARY KEY, s1 INT REFERENCES t10); Работает.
E141-06 Ограничения CHECK CREATE TABLE t12 (s1 INT PRIMARY KEY, s2 INT, CHECK (s1 = s2)); Работает.
E141-07 Значения столбцов по умолчанию CREATE TABLE t13 (s1 INT PRIMARY KEY, s2 INT DEFAULT -1); Работает.
E141-08 NOT NULL подразумевается для первичного ключа CREATE TABLE t14 (s1 INT PRIMARY KEY); Работает. NULL вставить не удастся, хотя столбец не объявлен явным образом как NOT NULL.
E141-10 Имена для FOREIGN KEY можно указывать в любом порядке CREATE TABLE t15 (s1 INT, s2 INT, PRIMARY KEY (s1,s2)); CREATE TABLE t16 (s1 INT PRIMARY KEY, s2 INT, FOREIGN KEY (s2,s1) REFERENCES t15 (s1,s2)); Работает.

E151, поддержка транзакций

Код возможности Возможность Пример Результаты тестов
E151-01 Инструкция COMMIT COMMIT; Ошибка. Tarantool поддерживает COMMIT, но перед этим требуется использовать START TRANSACTION.
E151-02 Инструкция ROLLBACK ROLLBACK; Работает.

E152, базовая инструкция SET TRANSACTION

Код возможности Возможность Пример Результаты тестов
E152-01 Инструкция SET TRANSACTION: предложение ISOLATION SERIALIZABLE SET TRANSACTION ISOLATION LEVEL SERIALIZABLE; Ошибка — в синтаксисе.
E152-02 Инструкция SET TRANSACTION: предложения READ ONLY и READ WRITE SET TRANSACTION READ ONLY; Ошибка — в синтаксисе.

E*, прочее

Код возможности Возможность Пример Результаты тестов
E153 Запросы, изменяющие данные, с подзапросами UPDATE "view_containing_subquery" SET column1=0; Ошибка.
E161 Комментарии SQL с двумя знаками минуса в начале --comment; Работает.
E171 Поддержка SQLSTATE DROP TABLE no_such_table; Ошибка. Tarantool возвращает сообщение об ошибке, но не строку SQLSTATE.
E182 Привязка базового языка   Работает. Любые коннекторы Tarantool должны иметь возможность вызвать box.execute().

F021, базовая информационная схема

Код возможности Возможность Пример Результаты тестов
F021 Базовая информационная схема SELECT * FROM information_schema.tables; Ошибка. Метаданные Tarantool не содержатся в схеме с таким именем (ошибка не учитывается в итоговом подсчете).

F031, базовые манипуляции со схемой

Код возможности Возможность Пример Результаты тестов
F031-01 Инструкция CREATE TABLE создает хранимые таблицы БД CREATE TABLE t20 (t20_1 INT NOT NULL); Ошибка. PRIMARY KEY всегда должен быть указан (эта ошибка будет учитываться только один раз).
F031-02 Инструкция CREATE VIEW CREATE VIEW t21 AS SELECT * FROM t20; Работает.
F031-03 Инструкция GRANT   Ошибка. Tarantool не поддерживает права, кроме как через NoSQL.
F031-04 Инструкция ALTER TABLE: добавление столбца ALTER TABLE t7 ADD COLUMN t7_2 VARCHAR(1) DEFAULT 'q'; Работает. Tarantool поддерживает ALTER TABLE, а в версии Tarantool 2.7 добавлена поддержка ADD COLUMN.
F031-13 Инструкция DROP TABLE: предложение RESTRICT DROP TABLE t20 RESTRICT; Ошибка. Tarantool поддерживает DROP TABLE, но не предложение RESTRICT.
F031-16 Инструкция DROP VIEW: предложение RESTRICT DROP VIEW v2 RESTRICT; Ошибка. Tarantool поддерживает DROP VIEW, но не предложение RESTRICT.
F031-19 Инструкция REVOKE: предложение RESTRICT   Ошибка. Tarantool не поддерживает права, кроме как через NoSQL.

F041, базовое объединение таблиц

Код возможности Возможность Пример Результаты тестов
F041-01 Операция inner join, но необязательно с ключевым словом INNER SELECT a.s1 FROM t7 a JOIN t7 b; Работает.
F041-02 Ключевое слово INNER SELECT a.s1 FROM t7 a INNER JOIN t7 b; Работает.
F041-03 LEFT OUTER JOIN SELECT t7.*,t22.* FROM t22 LEFT OUTER JOIN t7 ON (t22_1 = s1); Работает.
F041-04 RIGHT OUTER JOIN SELECT t7.*,t22.* FROM t22 RIGHT OUTER JOIN t7 ON (t22_1 = s1); Ошибка — в синтаксисе.
F041-05 Вложенные outer join SELECT t7.*,t22.* FROM t22 LEFT OUTER JOIN t7 ON (t22_1 = s1) LEFT OUTER JOIN t23; Работает.
F041-07 Таблица, полученная в результате операции left или right outer join, может быть использована в inner join SELECT t7.* FROM (t22 LEFT OUTER JOIN t7 ON (t22_1 = s1)) j INNER JOIN t22 ON (j.t22_4 = t7.s1); Работает.
F041-08 Все операторы сравнения поддерживаются SELECT * FROM t WHERE 0 = 1 OR 0 > 1 OR 0 < 1 OR 0 <> 1; Работает.

F051, базовая поддержка даты и времени

Код возможности Возможность Пример Результаты тестов
F051-01 Тип данных DATE (включая поддержку литерала DATE) CREATE TABLE dates (s1 DATE); Ошибка. Tarantool не поддерживает тип данных DATE.
F051-02 Тип данных TIME (включая поддержку литерала TIME) CREATE TABLE times (s1 TIME DEFAULT TIME '1:2:3'); Ошибка — в синтаксисе.
F051-03 Тип данных TIMESTAMP (включая поддержку литерала TIMESTAMP) CREATE TABLE timestamps (s1 TIMESTAMP); Ошибка — в синтаксисе.
F051-04 Предикат сравнения с типами данных DATE, TIME и TIMESTAMP SELECT * FROM dates WHERE s1 = s1; Ошибка. Типы данных даты и времени не поддерживаются.
F051-05 Явное преобразование CAST между типами даты и времени и типами символьных строк SELECT cast(s1 AS VARCHAR(10)) FROM dates; Ошибка. Типы данных даты и времени не поддерживаются.
F051-06 CURRENT_DATE SELECT current_date FROM t; Ошибка — в синтаксисе.
F051-07 LOCALTIME SELECT localtime FROM t; Ошибка — в синтаксисе.
F051-08 LOCALTIMESTAMP SELECT localtimestamp FROM t; Ошибка — в синтаксисе.

F081, UNION и EXCEPT в представлениях

Код возможности Возможность Пример Результаты тестов
F081 UNION и EXCEPT в представлениях CREATE VIEW vv AS SELECT * FROM t7 EXCEPT SELECT * * FROM t15; Работает.

F131, операции группировки

Код возможности Возможность Пример Результаты тестов
F131-01 Поддержка WHERE, GROUP BY и HAVING в запросах со сгруппированными представлениями CREATE VIEW vv2 AS SELECT * FROM vv GROUP BY s1; Работает.
F131-02 Поддержка нескольких таблиц в запросах со сгруппированными представлениями CREATE VIEW vv3 AS SELECT * FROM vv2,t30; Работает.
F131-03 Поддержка агрегатных функций в запросах со сгруппированными представлениями CREATE VIEW vv4 AS SELECT count(*) FROM vv2; Работает.
F131-04 Подзапросы с предложениями GROUP BY и HAVING и сгруппированными представлениями CREATE VIEW vv5 AS SELECT count(*) FROM vv2 GROUP BY s1 HAVING count(*) > 0; Работает.
F131-05 Инструкция SELECT, возвращающая одну строку, с GROUP BY и HAVING и сгруппированными представлениями SELECT count(*) FROM vv2 GROUP BY s1 HAVING count(*) > 0; Работает.

F181, поддержка нескольких модулей

Ошибка. В Tarantool отсутствуют модули.

F201, функция CAST

Код возможности Возможность Пример Результаты тестов
F201 Функция CAST SELECT cast(s1 AS INT) FROM t; Работает.

F221, явно заданное значение по умолчанию

Код возможности Возможность Пример Результаты тестов
F221 Явно заданное значение по умолчанию UPDATE t SET s1 = DEFAULT; Ошибка — в синтаксисе.

F261, выражение CASE

Код возможности Возможность Пример Результаты тестов
F261-01 Простой CASE SELECT CASE WHEN 1 = 0 THEN 5 ELSE 7 END FROM t; Работает.
F261-02 CASE с поиском SELECT CASE 1 WHEN 0 THEN 5 ELSE 7 END FROM t; Работает.
F261-03 NULLIF SELECT nullif(s1,7) FROM t; Работает
F261-04 COALESCE SELECT coalesce(s1,7) FROM t; Работает.

F311, инструкция определения схемы

Код возможности Возможность Результаты тестов
F311-01 CREATE SCHEMA Ошибка. В Tarantool отсутствуют схемы и базы данных.
F311-02 CREATE TABLE для хранимых таблиц БД Ошибка. В Tarantool нет CREATE TABLE в CREATE SCHEMA.
F311-03 CREATE VIEW Ошибка. В Tarantool нет CREATE VIEW в CREATE SCHEMA.
F311-04 CREATE VIEW: WITH CHECK OPTION Ошибка. В Tarantool нет CREATE VIEW в CREATE SCHEMA.
F311-05 Инструкция GRANT Ошибка. В Tarantool в составе CREATE SCHEMA нет GRANT.

F*, прочее

Код возможности Возможность Пример Результаты тестов
F471 Скалярные значения подзапросов SELECT s1 FROM t WHERE s1 = (SELECT count(*) FROM t); Работает.
F481 Расширенный предикат NULL SELECT * FROM t WHERE row(s1,s1) IS NOT NULL; Ошибка — в синтаксисе.
F812 Базовые флаги   Ошибка. Tarantool не поддерживает флаги.

S011, пользовательские типы

Код возможности Возможность Пример Результаты тестов
S011 Пользовательские типы CREATE TYPE x AS FLOAT; Ошибка. Tarantool не поддерживает пользовательские типы.

T321, базовые процедуры, вызываемые SQL

Код возможности Возможность Пример Результаты тестов
T321-01 Пользовательские функции без переопределения CREATE FUNCTION f() RETURNS INT RETURN 5; Ошибка. Пользовательские функции для SQL создаются с помощью Lua с другим синтаксисом.
T321-02 Пользовательские процедуры без переопределения CREATE PROCEDURE p() BEGIN END; Ошибка. Пользовательские функции для SQL создаются с помощью Lua с другим синтаксисом.
T321-03 Вызов функций SELECT f(1) FROM t; Работает. Tarantool может вызывать пользовательские Lua-функции.
T321-04 Инструкция CALL CALL p(); Ошибка. Tarantool не поддерживает инструкции CALL.
T321-05 Инструкция RETURN CREATE FUNCTION f() RETURNS INT RETURN 5; Ошибка. Tarantool не поддерживает инструкции RETURN.

T*, прочее

Код возможности Возможность Пример Результаты тестов
T631 Предикат IN с одним элементом списка SELECT * FROM t WHERE 1 IN (1); Работает.

Количество элементов с отметкой «Ошибка»: 67.

Количество элементов с отметкой «Работает»: 79.

Справочник по встроенным модулям

В данном справочнике рассматриваются встроенные Lua-модули Tarantool.

Примечание

Некоторые функции в данных модулях представляют собой аналоги функций из стандартных Lua-библиотек. Для достижения наилучшего результата мы рекомендуем использовать функции из встроенных модулей Tarantool.

Перечень Lua-модулей

Модуль box

Помимо выполнения фрагментов кода на Lua или определения собственных функций, с помощью модуля box и вложенных модулей можно использовать функции хранилища Tarantool.

Каждый вложенный модуль включает в себя одну или более Lua-функций. Несколько вложенных модулей включают в себя элементы класса, а также функции. Функции обеспечивают определение данных (create alter drop), управление данными (insert delete update upsert select replace) и просмотр состояния (просмотр содержимого спейсов, получение доступа к конфигурации сервера).

Чтобы найти ошибки, которые могут выдать вложенные модули box, используйте pcall.

Содержимое модуля box можно просмотреть во время исполнения кода с помощью команды box без аргументов. Модуль box включает в себя следующее:

Вложенный модуль box.backup

Модуль box.backup содержит две функции, которые помогают при работе с резервированным копированием.

Ниже приведен перечень всех функций модуля box.backup.

Имя Использование
box.backup.start() попросить сервер приостановить активности перед удалением устаревших резервных копий
box.backup.stop() проинформировать сервер, что можно вернуться к работе

box.backup.start()

backup.start([n])

Оповещает сервер о том, что следует приостановить все активности, связанные с удалением устаревших резервных копий.

Чтобы гарантировать возможность скопировать эти файлы, Tarantool не станет их удалять. При этом он не переходит в режим read-only, и создание контрольных точек делается по расписанию, как обычно.

Параметры:
  • n (number) – необязательный аргумент, начиная с Tarantool 1.10.1, который указывает нужную контрольную точку относительно самой свежей точки. Например, n = 0 означает “резервная копия будет создана на основе самой свежей контрольной точки”, n = 1 означает «резервная копия будет создана на основе контрольной точки, которая была создана перед самой свежей точкой», и т.д. По умолчанию n = 0.

Возвращает: таблицу с именами снапшотов и файлов vinyl, которые нужно скопировать

Пример:

tarantool> box.backup.start()
---
- - ./00000000000000000015.snap
  - ./00000000000000000000.vylog
  - ./513/0/00000000000000000002.index
  - ./513/0/00000000000000000002.run
...

box.backup.stop()

backup.stop()

Оповещает сервер о том, что можно вернуться к работе в обычном режиме.

Вложенный модуль box.cfg

Вложенный модуль box.cfg предназначен для системных администраторов, чтобы указать все параметры конфигурации сервера.

Чтобы посмотреть текущую конфигурацию, вызовите box.cfg без скобок:

tarantool> box.cfg
---
- checkpoint_count: 2
  too_long_threshold: 0.5
  slab_alloc_factor: 1.05
  memtx_max_tuple_size: 1048576
  background: false
  <...>
...

Для установки конкретных параметров используйте следующий синтаксис: box.cfg{key = value [, key = value ...] } (далее для краткости box.cfg{...}). Например:

tarantool> box.cfg{listen = 3301}

Параметры, не указанные в явном вызове box.cfg{...}, будут установлены в значения по умолчанию.

Если ввести box.cfg{} без параметров, Tarantool применит настройки по умолчанию:

tarantool> box.cfg{}
tarantool> box.cfg -- sorted in the alphabetic order
---
- background                   = false
  checkpoint_count             = 2
  checkpoint_interval          = 3600
  checkpoint_wal_threshold     = 1000000000000000000
  coredump                     = false
  custom_proc_title            = nil
  feedback_enabled             = true
  feedback_host                = 'https://feedback.tarantool.io'
  feedback_interval            = 3600
  force_recovery               = false
  hot_standby                  = false
  instance_uuid                = nil -- generated automatically
  io_collect_interval          = nil
  iproto_threads               = 1
  listen                       = nil
  log                          = nil
  log_format                   = plain
  log_level                    = 5
  log_nonblock                 = true
  memtx_dir                    = '.'
  memtx_max_tuple_size         = 1024 * 1024
  memtx_memory                 = 256 * 1024 *1024
  memtx_min_tuple_size         = 16
  net_msg_max                  = 768
  pid_file                     = nil
  readahead                    = 16320
  read_only                    = false
  replicaset_uuid              = nil -- generated automatically
  replication                  = nil
  replication_anon             = false
  replication_connect_timeout  = 30
  replication_skip_conflict    = false
  replication_sync_lag         = 10
  replication_sync_timeout     = 300
  replication_timeout          = 1
  slab_alloc_factor            = 1.05
  snap_io_rate_limit           = nil
  sql_cache_size               = 5242880
  strip_core                   = true
  too_long_threshold           = 0.5
  username                     = nil
  vinyl_bloom_fpr              = 0.05
  vinyl_cache                  = 128 * 1024 * 1024
  vinyl_dir                    = '.'
  vinyl_max_tuple_size         = 1024 * 1024* 1024 * 1024
  vinyl_memory                 = 128 * 1024 * 1024
  vinyl_page_size              = 8 * 1024
  vinyl_range_size             = nil
  vinyl_read_threads           = 1
  vinyl_run_count_per_level    = 2
  vinyl_run_size_ratio         = 3.5
  vinyl_timeout                = 60
  vinyl_write_threads          = 4
  wal_dir                      = '.'
  wal_dir_rescan_delay         = 2
  wal_max_size                 = 256 * 1024 * 1024
  wal_mode                     = 'write'
  worker_pool_threads          = 4
  work_dir                     = nil

Первый вызов box.cfg{...} (с параметрами или без них) запускает модуль базы данных Tarantool под названием box.

Команда box.cfg{...} также перезагружает файлы с данными длительного хранения в оперативную память при перезапуске после получения данных.

Вложенный модуль box.ctl

The wait_ro (wait until read-only) and wait_rw (wait until read-write) functions are useful during server initialization. To see whether a function is already in read-only or read-write mode, check box.info.ro.

Для box.once() есть особое предназначение. Например, при инициализации реплика может вызвать функцию box.once(), пока сервер все еще находится в режиме только для чтения, и не сможет применить изменения однократно до окончательной инициализации реплики. Это может привести к конфликту между мастером и репликой, если мастер находится в режиме чтения и записи, а реплика доступна только для чтения. Ожидание условия «read only mode = false» (режим только для чтения отключен) решает эту проблему.

Ниже приведен перечень всех функций модуля box.ctl.

Имя Использование
box.ctl.wait_ro() Дождаться, пока не будет выполнено box.info.ro
box.ctl.wait_rw() Дождаться, пока не перестанет соблюдаться box.info.ro
box.ctl.on_schema_init() Создать «schema_init триггер»
box.ctl.on_shutdown() Создать «shutdown триггер»
box.ctl.on_recovery_state() Create a trigger executed on different stages of a node recovery or initial configuration
box.ctl.on_election() Create a trigger executed every time the current state of a replica set node in regard to leader election changes
box.ctl.set_on_shutdown_timeout() Set a timeout in seconds for the on_shutdown trigger
box.ctl.is_recovery_finished() Check if recovery has finished
box.ctl.promote() Wait, then choose replication leader
box.ctl.demote() Revoke the leader role from the instance
box.ctl.make_bootstrap_leader() Make the instance a bootstrap leader of a replica set

box.ctl.wait_ro()

box.ctl.wait_ro([timeout])

Дождаться, пока не будет выполнено box.info.ro.

Параметры:
  • timeout (number) – максимальное количество секунд ожидания
возвращает:

нулевое значение nil или ошибка, которая может возникнуть из-за превышения времени ожидания или прерывания работы файбера

Пример:

tarantool> box.info().ro
---
- false
...

tarantool> n = box.ctl.wait_ro(0.1)
---
- error: timed out
...

box.ctl.wait_rw()

box.ctl.wait_rw([timeout])

Дождаться, пока не перестанет соблюдаться box.info.ro.

Параметры:
  • timeout (number) – максимальное количество секунд ожидания
возвращает:

нулевое значение nil или ошибка, которая может возникнуть из-за превышения времени ожидания или прерывания работы файбера

Пример:

tarantool> box.ctl.wait_rw(0.1)
---
...

box.ctl.on_schema_init()

box.ctl.on_schema_init(trigger-function[, old-trigger-function])

Создать триггер schema_init. Функция триггера будет выполнена, когда box.cfg{} произойдет в первый раз. То есть триггер schema_init вызывается до начала конфигурирования и восстановления сервера, и поэтому box.ctl.on_schema_init должен быть вызван до вызова box.cfg.

Параметры:
  • trigger-function (function) – функция, в которой будет триггер
  • old-trigger-function (function) – существующая функция с триггером, которую заменит новая
возвращает:

nil или указатель функции

Если указаны параметры (nil, old-trigger-function), старый триггер будет удален.

Обычно используется следующее: сделать триггерную функцию schema_init, которая создает триггерную функцию before_replace на системном спейсе. Таким образом, поскольку системные спейсы создаются при старте сервера, триггеры before_replace будут активированы для каждого кортежа в каждом системном спейсе. Например, такой триггер может изменить механизм хранения заданного спейса, или сделать заданный спейс локальной репликой во время загрузки реплики. Выполнение такого изменения после box.cfg не является надежным, поскольку другие подключения могут использовать базу данных до внесения изменения.

Подробная информация о характеристиках триггера находится в разделе Триггеры.

Пример:

Предположим, что до того, как сервер будет полностью готов к подключениям, вы хотите убедиться, что движком space_name является vinyl. Поэтому вы хотите сделать триггер, который будет активирован при вставке кортежа в системный спейс _space. В этом случае может получиться мастер, который имеет space-name с engine='memtx' и реплику, которая имеет space_name с engine='vinyl', с тем же самым содержимым.

function function_for_before_replace(old, new)
  if old == nil and new ~= nil and new[3] == 'space_name' and new[4] ~= 'vinyl' then
    return new:update{{'=', 4, 'vinyl'}}
  end
end

box.ctl.on_schema_init(function()
  box.space._space:before_replace(function_for_before_replace)
end)

box.cfg{replication='master_uri', ...}

box.ctl.on_shutdown()

box.ctl.on_shutdown(trigger-function[, old-trigger-function])

Создать «триггер выключения». Триггер-функция будет выполняться всякий раз, когда происходит os.exit(), или когда сервер выключается после получения сигнала SIGTERM или SIGINT или SIGHUP (но не после сигнала SIGSEGV или SIGABORT или любого другого сигнала, вызывающего немедленное завершение программы).

Параметры:
  • trigger-function (function) – функция, в которой будет триггер
  • old-trigger-function (function) – существующая функция с триггером, которую заменит новая
возвращает:

nil или указатель функции

Если указаны параметры (nil, old-trigger-function), старый триггер будет удален.

Если вы хотите установить таймаут для этого триггера, используйте функцию set_on_shutdown_timeout.

box.ctl.on_recovery_state()

box.ctl.on_recovery_state(trigger-function)

Since: 2.11.0

Create a trigger executed on different stages of a node recovery or initial configuration. Note that you need to set the box.ctl.on_recovery_state trigger before the initial box.cfg call.

Параметры:
  • trigger-function (function) – a trigger function
Return:

nil or a function pointer

A registered trigger function is run on each of the supported recovery state and receives the state name as a parameter:

  • snapshot_recovered: the node has recovered the snapshot files.
  • wal_recovered: the node has recovered the WAL files.
  • indexes_built: the node has built secondary indexes for memtx spaces. This stage might come before any actual data is recovered. This means that the indexes are available right after the first tuple is recovered.
  • synced: the node has synced with enough remote peers. This means that the node changes the state from orphan to running.

All these states are passed during the initial box.cfg call when recovering from the snapshot and WAL files. Note that the synced state might be reached after the initial box.cfg call finishes. For example, if replication_sync_timeout is set to 0, the node finishes box.cfg without reaching synced and stays orphan. Once the node is synced with enough remote peers, the synced state is reached.

Примечание

When bootstrapping a fresh cluster with no data, all the instances in this cluster execute triggers on the same stages for consistency. For example, snapshot_recovered and wal_recovered run when the node finishes a cluster’s bootstrap or finishes joining to an existing cluster.

Example:

The example below shows how to log a specified message when each state is reached.

local log = require('log')
local log_recovery_state = function(state)
    log.info(state .. ' state reached')
end
box.ctl.on_recovery_state(log_recovery_state)

box.ctl.on_election()

box.ctl.on_election(trigger-function)

Since: 2.10.0

Create a trigger executed every time the current state of a replica set node in regard to leader election changes. The current state is available in the box.info.election table.

The trigger doesn’t accept any parameters. You can see the changes in box.info.election and box.info.synchro.

Параметры:
  • trigger-function (function) – a trigger function
Return:

nil or a function pointer

box.ctl.set_on_shutdown_timeout()

box.ctl.set_on_shutdown_timeout([timeout])

Set a timeout for the on_shutdown trigger. If the timeout has expired, the server stops immediately regardless of whether any on_shutdown triggers are left unexecuted.

Параметры:
  • timeout (double) – time to wait for the trigger to be completed. The default value is 3 seconds.
Return:

nil

box.ctl.is_recovery_finished()

box.ctl.is_recovery_finished()

Since version 2.5.3.

Check whether the recovery process has finished. Until it has finished, space changes such as insert or update are not possible.

возвращает:true if recovery has finished, otherwise false
возвращаемое значение:
 boolean (логический)

box.ctl.promote()

promote()

Since version 2.6.2. Renamed in release 2.6.3.

Wait, then choose new replication leader.

For synchronous transactions it is possible that a new leader will be chosen but the transactions of the old leader have not been completed. Therefore to finalize the transaction, the function box.ctl.promote() should be called, as mentioned in the notes for leader election. The old name for this function is box.ctl.clear_synchro_queue().

The election state should change to leader.

Parameters: none

возвращает:nil или указатель функции

box.ctl.demote()

demote()

Since version 2.10.0.

Revoke the leader role from the instance.

On synchronous transaction queue owner, the function works in the following way:

  • If box.cfg.election_mode is off, the function writes a DEMOTE request to WAL. The DEMOTE request clears the ownership of the synchronous transaction queue, while the PROMOTE request assigns it to a new instance.
  • If box.cfg.election_mode is enabled in any mode, then the function makes the instance start a new term and give up the leader role.

On instances that are not queue owners, the function does nothing and returns immediately.

Parameters: none

Return:nil

box.ctl.make_bootstrap_leader()

make_bootstrap_leader()

Since: 3.0.0.

Make the instance a bootstrap leader of a replica set.

To be able to make the instance a bootstrap leader manually, the replication.bootstrap_strategy configuration option should be set to supervised. In this case, the instances do not choose a bootstrap leader automatically but wait for it to be appointed manually. Configuration fails if no bootstrap leader is appointed during a replication.connect_timeout.

Примечание

When a new instance joins a replica set configured with the supervised bootstrap strategy, this instance doesn’t choose the bootstrap leader automatically but joins to the instance on which box.ctl.make_bootstrap_leader() was executed last time.

Вложенный модуль box.error

The box.error submodule can be used to work with errors in your application. For example, you can get the information about the last error raised by Tarantool or raise custom errors manually.

The difference between raising an error using box.error and a Lua’s built-in error function is that when the error reaches the client, its error code is preserved. In contrast, a Lua error would always be presented to the client as ER_PROC_LUA.

Примечание

To learn how to handle errors in your application, see the Handling errors section.

Creating an error

You can create an error object using the box.error.new() function. The created object can be passed to box.error() to raise the error. You can also raise the error using error_object:raise().

The example below shows how to create and raise the error with the specified code and reason.

local custom_error = box.error.new({ code = 500,
                                     reason = 'Internal server error' })

box.error(custom_error)
--[[
---
- error: Internal server error
...
--]]

box.error.new() provides different overloads for creating an error object with different parameters. These overloads are similar to the box.error() overloads described in the next section.

Raising an error

To raise an error, call the box.error() function. This function can accept the specified error parameters or an error object created using box.error.new(). In both cases, you can use box.error() to raise the following error types:

Custom error

The following box.error() overloads are available for raising a custom error:

Примечание

The same overloads are available for box.error.new().

box.error({ reason = string[, …] })

In the example below, box.error() accepts a Lua table with the specified error code and reason:

box.error { code = 500,
            reason = 'Custom server error' }
--[[
---
- error: Custom server error
...
--]]

The next example shows how to specify a custom error type:

box.error { code = 500,
            reason = 'Internal server error',
            type = 'CustomInternalError' }
--[[
---
- error: Internal server error
...
--]]

When a custom type is specified, it is returned in the error_object.type attribute. When it is not specified, error_object.type returns one of the built-in errors, such as ClientError or OutOfMemory.

box.error(type, reason[, …])

This example shows how to raise an error with the type and reason specified in the box.error() arguments:

box.error('CustomConnectionError', 'cannot connect to the given port')
--[[
---
- error: cannot connect to the given port
...
--]]

You can also use a format string to compose an error reason:

box.error('CustomConnectionError', '%s cannot connect to the port %u', 'client', 8080)
--[[
---
- error: client cannot connect to the port 8080
...
--]]

Tarantool error

The box.error(code[, …]) overload raises a predefined Tarantool error specified by its identifier. The error code defines the error message format and the number of required arguments. In the example below, no arguments are passed for the box.error.READONLY error code:

box.error(box.error.READONLY)
--[[
---
- error: Can't modify data on a read-only instance
...
--]]

For the box.error.NO_SUCH_USER error code, you need to pass one argument:

box.error(box.error.NO_SUCH_USER, 'John')
--[[
---
- error: User 'John' is not found
...
--]]

box.error.CREATE_SPACE requires two arguments:

box.error(box.error.CREATE_SPACE, 'my_space', 'the space already exists')
--[[
---
- error: 'Failed to create space ''my_space'': the space already exists'
...
--]]

Getting the last error

To get the last raised error, call box.error.last():

box.error.last()
--[[
---
- error: Internal server error
...
--]]

Obtaining error details

To get error details, call the error_object.unpack(). Error details may include an error code, type, message, and trace.

box.error.last():unpack()
--[[
---
- code: 500
  base_type: CustomError
  type: CustomInternalError
  custom_type: CustomInternalError
  message: Internal server error
  trace:
  - file: '[string "custom_error = box.error.new({ code = 500,..."]'
    line: 1
...
--]]

Setting the last error

You can set the last error explicitly by calling box.error.set():

-- Create two errors --
local error1 = box.error.new({ code = 500, reason = 'Custom error 1' })
local error2 = box.error.new({ code = 505, reason = 'Custom error 2' })

-- Raise the first error --
box.error(error1)
--[[
---
- error: Custom error 1
...
--]]

-- Get the last error --
box.error.last()
--[[
---
- Custom error 1
...
--]]

-- Set the second error as the last error --
box.error.set(error2)
--[[
---
...
--]]

-- Get the last error --
box.error.last()
--[[
---
- Custom error 2
...
--]]

Error lists

error_object provides the API for organizing errors into lists. To set and get the previous error, use the error_object:set_prev() method and error_object.prev attribute.

local base_server_error = box.error.new({ code = 500,
                                          reason = 'Base server error',
                                          type = 'BaseServerError' })
local storage_server_error = box.error.new({ code = 507,
                                             reason = 'Not enough storage',
                                             type = 'StorageServerError' })

base_server_error:set_prev(storage_server_error)
--[[
---
...
--]]

box.error(base_server_error)
--[[
---
- error: Base server error
...
--]]

box.error.last().prev:unpack()
--[[
---
- code: 507
  base_type: CustomError
  type: StorageServerError
  custom_type: StorageServerError
  message: Not enough storage
  trace:
  - file: '[string "storage_server_error = box.error.new({ code =..."]'
    line: 1
...
--]]

Cycles are not allowed for error lists:

storage_server_error:set_prev(base_server_error)
--[[
---
- error: 'builtin/error.lua:120: Cycles are not allowed'
...
--]]

Setting the previous error does not erase its own previous members:

-- e1 -> e2 -> e3 -> e4
e1:set_prev(e2)
e2:set_prev(e3)
e3:set_prev(e4)
e2:set_prev(e5)
-- Now there are two lists: e1 -> e2 -> e5 and e3 -> e4

IPROTO also supports stacked diagnostics. See details in MessagePack extensions – The ERROR type.

Clearing errors

To clear the errors, call box.error.clear().

box.error.clear()
--[[
---
...
--]]
box.error.last()
--[[
---
- null
...
--]]

API Reference

Below is a list of box.error functions and related objects.

Имя Назначение
box.error() Raise the last error or the error defined by the specified parameters
box.error.last() Get the last raised error
box.error.clear() Clear the errors
box.error.new() Create the error but do not raise it
box.error.set() Set the specified error as the last system error explicitly
error_object An object that defines an error

box.error()

box.error()

Raise the last error.

See also: box.error.last()

box.error(error_object)

Raise the error defined by error_object.

Параметры:

Example

local custom_error = box.error.new({ code = 500,
                                     reason = 'Internal server error' })

box.error(custom_error)
--[[
---
- error: Internal server error
...
--]]
box.error({ reason = string[, code = number, type = string] }])

Raise the error defined by the specified parameters.

Параметры:
  • reason (string) – an error description
  • code (integer) – (optional) a numeric code for this error
  • type (string) – (optional) an error type

Example 1

box.error { code = 500,
            reason = 'Custom server error' }
--[[
---
- error: Custom server error
...
--]]

Example 2: custom type

box.error { code = 500,
            reason = 'Internal server error',
            type = 'CustomInternalError' }
--[[
---
- error: Internal server error
...
--]]
box.error(type, reason[, ...])

Raise the error defined by the specified type and description.

Параметры:
  • type (string) – an error type
  • reason (string) – an error description
  • ... – description arguments

Example 1: without arguments

box.error('CustomConnectionError', 'cannot connect to the given port')
--[[
---
- error: cannot connect to the given port
...
--]]

Example 2: with arguments

box.error('CustomConnectionError', '%s cannot connect to the port %u', 'client', 8080)
--[[
---
- error: client cannot connect to the port 8080
...
--]]
box.error(code[, ...])

Raise a predefined Tarantool error specified by its identifier. You can see all Tarantool errors in the errcode.h file.

Параметры:
  • code (number) – a pre-defined error identifier; Lua constants that correspond to those Tarantool errors are defined as members of box.error, for example, box.error.NO_SUCH_USER == 45
  • ... – description arguments

Example 1: no arguments

box.error(box.error.READONLY)
--[[
---
- error: Can't modify data on a read-only instance
...
--]]

Example 2: one argument

box.error(box.error.NO_SUCH_USER, 'John')
--[[
---
- error: User 'John' is not found
...
--]]

Example 3: two arguments

box.error(box.error.CREATE_SPACE, 'my_space', 'the space already exists')
--[[
---
- error: 'Failed to create space ''my_space'': the space already exists'
...
--]]

box.error.last()

box.error.last()

Get the last raised error.

Return:an error_object representing the last error

Example

box.error.last()
--[[
---
- error: Internal server error
...
--]]

See also: error_object:unpack()

box.error.clear()

box.error.clear()

Clear the errors.

Example

box.error.clear()
--[[
---
...
--]]
box.error.last()
--[[
---
- null
...
--]]

box.error.new()

box.error.new({ reason = string[, code = number, type = string] }])

Create an error object with the specified parameters.

Параметры:
  • reason (string) – an error description
  • code (integer) – (optional) a numeric code for this error
  • type (string) – (optional) an error type

Example 1

local custom_error = box.error.new({ code = 500,
                                     reason = 'Internal server error' })

box.error(custom_error)
--[[
---
- error: Internal server error
...
--]]

Example 2: custom type

local custom_error = box.error.new({ code = 500,
                                     reason = 'Internal server error',
                                     type = 'CustomInternalError' })

box.error(custom_error)
--[[
---
- error: Internal server error
...
--]]
box.error.new(type, reason[, ...])

Create an error object with the specified type and description.

Параметры:
  • type (string) – an error type
  • reason (string) – an error description
  • ... – description arguments

Example

local custom_error = box.error.new('CustomInternalError', 'Internal server error')

box.error(custom_error)
--[[
---
- error: Internal server error
...
--]]
box.error.new(code[, ...])

Create a predefined Tarantool error specified by its identifier. You can see all Tarantool errors in the errcode.h file.

Параметры:
  • code (number) – a pre-defined error identifier; Lua constants that correspond to those Tarantool errors are defined as members of box.error, for example, box.error.NO_SUCH_USER == 45
  • ... – description arguments

Example 1: one argument

local custom_error = box.error.new(box.error.NO_SUCH_USER, 'John')

box.error(custom_error)
--[[
---
- error: User 'John' is not found
...
--]]

Example 2: two arguments

local custom_error = box.error.new(box.error.CREATE_SPACE, 'my_space', 'the space already exists')

box.error(custom_error)
--[[
---
- error: 'Failed to create space ''my_space'': the space already exists'
...
--]]

box.error.set()

box.error.set(error_object)

Since: 2.4.1

Set the specified error as the last system error explicitly. This error is returned by box.error.last().

Параметры:

Example

-- Create two errors --
local error1 = box.error.new({ code = 500, reason = 'Custom error 1' })
local error2 = box.error.new({ code = 505, reason = 'Custom error 2' })

-- Raise the first error --
box.error(error1)
--[[
---
- error: Custom error 1
...
--]]

-- Get the last error --
box.error.last()
--[[
---
- Custom error 1
...
--]]

-- Set the second error as the last error --
box.error.set(error2)
--[[
---
...
--]]

-- Get the last error --
box.error.last()
--[[
---
- Custom error 2
...
--]]

error_object

object error_object

An object that defines an error. error_object is returned by the following methods:

error_object:unpack()

Get error details that may include an error code, type, message, and trace.

Example

box.error.last():unpack()
--[[
---
- code: 500
  base_type: CustomError
  type: CustomInternalError
  custom_type: CustomInternalError
  message: Internal server error
  trace:
  - file: '[string "custom_error = box.error.new({ code = 500,..."]'
    line: 1
...
--]]

Примечание

Depending on the error type, error details may include other attributes, such as errno or reason.

error_object:raise()

Raise the current error.

See also: Raising an error

error_object:set_prev(error_object)

Since: 2.4.1

Set the previous error for the current one.

Параметры:

See also: Error lists

error_object.prev

Since: 2.4.1

Get the previous error for the current one.

Rtype:error_object

See also: Error lists

error_object.code

The error code. This attribute may return a custom error code or a Tarantool error code.

Rtype:number
error_object.type

The error type.

Rtype:string

See also: Custom error

error_object.message

The error message.

Rtype:string
error_object.trace

The error trace.

Rtype:table
error_object.errno

If the error is a system error (for example, a socket or file IO failure), returns a C standard error number.

Rtype:number
error_object.reason

Since: 2.10.0

Returns the box.info.ro_reason value at the moment of throwing the box.error.READONLY error.

The following values may be returned:

  • election if the instance has box.cfg.election_mode set to a value other than off and this instance is not a leader. In this case, error_object may include the following attributes: state, leader_id, leader_uuid, and term.
  • synchro if the synchronous queue has an owner that is not the given instance. This error usually happens if synchronous replication is used and another instance is called box.ctl.promote(). In this case, error_object may include the queue_owner_id, queue_owner_uuid, and term attributes.
  • config if the box.cfg.read_only is set to true.
  • orphan if the instance is in the orphan state.

Примечание

If multiple reasons are true at the same time, then only one is returned in the following order of preference: election, synchro, config, orphan.

Rtype:string
error_object.state

Since: 2.10.0

For the box.error.READONLY error, returns the current state of a replica set node in regards to leader election (see box.info.election.state). This attribute presents if the error reason is election.

Rtype:string
error_object.leader_id

Since: 2.10.0

For the box.error.READONLY error, returns a numeric identifier (box.info.id) of the replica set leader. This attribute may present if the error reason is election.

Rtype:number
error_object.leader_uuid

Since: 2.10.0

For the box.error.READONLY error, returns a globally unique identifier (box.info.uuid) of the replica set leader. This attribute may present if the error reason is election.

error_object.queue_owner_id

Since: 2.10.0

For the box.error.READONLY error, returns a numeric identifier (box.info.id) of the synchronous queue owner. This attribute may present if the error reason is synchro.

Rtype:number
error_object.queue_owner_uuid

Since: 2.10.0

For the box.error.READONLY error, returns a globally unique identifier (box.info.uuid) of the synchronous queue owner. This attribute may present if the error reason is synchro.

error_object.term

Since: 2.10.0

For the box.error.READONLY error, returns the current election term (see box.info.election.term). This attribute may present if the error reason is election or synchro.

Вложенный модуль box.index

Вложенный модуль box.index обеспечивает доступ к схемам индекса и ключам индекса в режиме только для чтения. Индексы хранятся в массиве box.space.имя-спейса.index в каждом спейсе. Они предоставляют API для упорядоченной итерации по кортежам. Этот API представляет собой прямую привязку к соответствующим методам объектов типа box.index в движке базы данных.

Ниже приведен перечень всех функций и элементов модуля box.index.

Имя Использование
Примеры для box.index Несколько полезных примеров
space_object:create_index() Создание индекса
index_object.unique Флаг, если индекс уникальный – true
index_object.type Тип индекса
index_object:parts Массив полей с ключами индекса
index_object:pairs() Подготовка к итерации
index_object:select() Выбор одного или более кортежей по индексу
index_object:get() Выбор кортежа по индексу
index_object:min() Поиск минимального значения в индексе
index_object:max() Поиск максимального значения в индексе
index_object:random() Поиск случайного значения в индексе
index_object:count() Подсчет кортежей с совпадающим значением ключа
index_object:update() Обновление кортежа
index_object:delete() Удаление кортежа по ключу
index_object:alter() Изменение индекса
index_object:drop() Удаление индекса
index_object:rename() Переименование индекса
index_object:bsize() Подсчет байтов для индекса
index_object:stat() Получение статистических данных по индексу
index_object:compact() Удаление неиспользуемого пространства индекса
index_object:tuple_pos() Return a tuple’s position for an index
index_object extensions Любая функция / метод, которые хочет добавить любой пользователь

Примеры для box.index

Пример использования функций box

Данный пример сработает на конфигурации из песочницы, описанной в предисловии, то есть создан спейс под названием tester с первичным числовым ключом. Функция в примере выполнит следующие действия:

The function uses Tarantool box functions box.space…select, box.space…replace, fiber.time, uuid.str. The function uses Lua functions os.date() and string.sub().

function example()
  local a, b, c, table_of_selected_tuples, d
  local replaced_tuple, time_field
  local formatted_time_field
  local fiber = require('fiber')
  table_of_selected_tuples = box.space.tester:select{1000}
  if table_of_selected_tuples ~= nil then
    if table_of_selected_tuples[1] ~= nil then
      if #table_of_selected_tuples[1] == 3 then
        box.error({code=1, reason='This tuple already has 3 fields'})
      end
    end
  end
  replaced_tuple = box.space.tester:replace
    {1000,  require('uuid').str(), tostring(fiber.time())}
  time_field = tonumber(replaced_tuple[3])
  formatted_time_field = os.date("%Y-%m-%d %H:%M:%S", time_field)
  c = time_field % 1
  d = string.sub(c, 3, 6)
  formatted_time_field = formatted_time_field .. '.' .. d
  return formatted_time_field
end

… А вот что происходит, когда вызывается функция:

tarantool> box.space.tester:delete(1000)
---
- [1000, '264ee2da03634f24972be76c43808254', '1391037015.6809']
...
tarantool> example(1000)
---
- 2014-01-29 16:11:51.1582
...
tarantool> example(1000)
---
- error: 'This tuple already has 3 fields'
...

Пример с заданным пользователем итератором

Здесь приведен пример того, как создать свой собственный итератор. Функция paged_iter представляет собой «функцию с итератором», что поймут только разработчики, которые ознакомились с разделом руководства по Lua Итераторы и замыкания. Она делает постраничную выборку, то есть возвращает 10 кортежей одновременно из таблицы под названием «t», первичный ключ которой определен с помощью create_index('primary',{parts={1,'string'}}).

function paged_iter(search_key, tuples_per_page)
  local iterator_string = "GE"
  return function ()
  local page = box.space.t.index[0]:select(search_key,
    {iterator = iterator_string, limit=tuples_per_page})
  if #page == 0 then return nil end
  search_key = page[#page][1]
  iterator_string = "GT"
  return page
  end
end

Разработчикам, использующим paged_iter, необязательно знать, почему она работает, следует лишь понимать, что вызвав функцию в цикле, можно получать 10 кортежей за раз до тех пор, пока кортежи не кончатся.

В данном примере кортежи лишь выводятся по странице за раз. Но легко изменить функцию, например, путем передачи управления после каждой выборки или с помощью прерывания, если кортежи не будут соответствовать дополнительным критериям.

for page in paged_iter("X", 10) do
  print("New Page. Number Of Tuples = " .. #page)
  for i = 1, #page, 1 do
    print(page[i])
  end
end

Пример использования box.index
с индексом типа RTREE для поиска в пространственных данных

Этот вложенный модуль может использоваться для поиска в пространственных данных, если тип индекса – RTREE. Существуют операции для поиска прямоугольников (геометрические фигуры с 4 углами и 4 сторонами) и параллелепипедов (геометрические фигуры с количеством углов более 4 и количеством сторон более 4, которые иногда называются гиперпрямоугольниками). В данном руководстве используется термин прямоугольник-или-параллелепипед для всего класса объектов, который включает в себя прямоугольники и параллелепипеды. Примерами иллюстрируются только прямоугольники.

Прямоугольники описаны в соответствии с координатами по оси X (горизонтальной оси) и оси Y (вертикальной оси) на сетке произвольного размера. Ниже представлен рисунок четырех прямоугольников на сетке с 11 горизонтальными точками и 11 вертикальными точками:

      X AXIS
           1   2   3   4   5   6   7   8   9   10  11
        1
        2  #-------+                                           <-Прямоугольник №1
Y AXIS  3  |       |
        4  +-------#
        5          #-----------------------+                   <-Прямоугольник №2
        6          |                       |
        7          |   #---+               |                   <-Прямоугольник №3
        8          |   |   |               |
        9          |   +---#               |
        10         +-----------------------#
        11                                     #               <-Прямоугольник №4

Прямоугольники определяются в соответствии со следующей схемой: {верхняя левая координата по оси X, верхняя левая координата по оси Y, нижняя правая координата по оси X, нижняя правая координата по оси Y} – или коротко: {x1,y1,x2,y2}. Таким образом, на рисунке … Прямоугольник № 1 начинается в точке 1 по оси X и точке 2 по оси Y, а заканчивается в точке 3 по оси X и точке 4 по оси Y, поэтому его координаты будут следующие: {1,2,3,4}. Координаты Прямоугольника № 2: {3,5,9,10}. Координаты Прямоугольника № 3: {4,7,5,9}. И наконец, координаты Прямоугольника № 4: {10,11,10,11}. Прямоугольник № 4, на самом деле, является точкой, поскольку у него нулевая ширина и нулевая высота, так что его можно описать всего двумя числами: {10,11}.

Некоторые отношения между прямоугольниками могут быть описаны так: «Прямоугольник №1 является ближайшим соседом Прямоугольника №2», а «Прямоугольник №3 полностью находится внутри Прямоугольника №2».

Сейчас создадим спейс и добавим RTREE-индекс.

tarantool> s = box.schema.space.create('rectangles')
tarantool> i = s:create_index('primary', {
         >   type = 'HASH',
         >   parts = {1, 'unsigned'}
         > })
tarantool> r = s:create_index('rtree', {
         >   type = 'RTREE',
         >   unique = false,
         >   parts = {2, 'ARRAY'}
         > })

Поле №1 не имеет значения, мы создаем его лишь потому, что необходим первичный индекс. (RTREE-индексы не могут быть уникальными, поэтому не могут быть первичными индексами.) Второе поле должно быть массивом («array»), что означает, что его значения должны представлять собой точки {x,y} или прямоугольники {x1,y1,x2,y2}. Заполним таблицу, вставив два кортежа с координатами Прямоугольника №2 и Прямоугольника №4.

tarantool> s:insert{1, {3, 5, 9, 10}}
tarantool> s:insert{2, {10, 11}}

Затем, после описания типов RTREE-итераторов (RTREE iterator types), можно произвести поиск прямоугольников с помощью данных запросов:

tarantool> r:select({10, 11, 10, 11}, {iterator = 'EQ'})
---
- - [2, [10, 11]]
...
tarantool> r:select({4, 7, 5, 9}, {iterator = 'GT'})
---
- - [1, [3, 5, 9, 10]]
...
tarantool> r:select({1, 2, 3, 4}, {iterator = 'NEIGHBOR'})
---
- - [1, [3, 5, 9, 10]]
  - [2, [10, 11]]
...

Запрос №1 возвращает 1 кортеж, потому что точка {10,11} представляет собой то же, что и прямоугольник {10,11,10,11} («Прямоугольник №4» на рисунке). Запрос № 2 возвращает 1 кортеж, потому что прямоугольник {4,7,5,9}, который был «Прямоугольником №3» на рисунке находится полностью внутри {3,5,9,10}, что представляет собой Прямоугольник № 2. Запрос № 3 возвращает 2 кортежа, потому что итератор NEIGHBOR (сосед) всегда возвращает все кортежи, а первым найденным кортежем будет {3,5,9,10} («Прямоугольник №2» на рисунке), потому что он является ближайшим соседом {1,2,3,4} («Прямоугольник №1» на рисунке).

Теперь создадим спейс и индекс для кубоидов, которые представляют собой прямоугольники-или-параллелепипеды, у которых 6 углов и 6 сторон.

tarantool> s = box.schema.space.create('R')
tarantool> i = s:create_index('primary', {parts = {1, 'unsigned'}})
tarantool> r = s:create_index('S', {
         >   type = 'RTREE',
         >   unique = false,
         >   dimension = 3,
         >   parts = {2, 'ARRAY'}
         > })

Здесь задается дополнительный параметр dimension=3. По умолчанию, измерений 2, поэтому не было необходимости указывать данный параметр в примерах для прямоугольника. Максимальное количество измерений – 20. Что касается вставки и выборки, здесь будет 6 координат. Например:

tarantool> s:insert{1, {0, 3, 0, 3, 0, 3}}
tarantool> r:select({1, 2, 1, 2, 1, 2}, {iterator = box.index.GT})

Теперь создадим спейс и индекс для пространственных объектов с метрикой расстояния городских кварталов (метрика Манхэттена), которые представляют собой прямоугольники-или-параллелепипеды; соседи для них рассчитываются иным образом.

tarantool> s = box.schema.space.create('R')
tarantool> i = s:create_index('primary', {parts = {1, 'unsigned'}})
tarantool> r = s:create_index('S', {
         >   type = 'RTREE',
         >   unique = false,
         >   distance = 'manhattan',
         >   parts = {2, 'ARRAY'}
         > })

Здесь задается дополнительный параметр distance='manhattan'. По умолчанию, расстояние измеряется по Евклидовой метрике, что лучше всего подходит для измерений по прямой линии. Другой способ расчета расстояния по метрике Манхэттена („manhattan“), который больше подходит, если необходимо следовать линиям сетки, а не по прямой.

tarantool> s:insert{1, {0, 3, 0, 3}}
tarantool> r:select({1, 2, 1, 2}, {iterator = box.index.NEIGHBOR})

Другие примеры поиска в пространственных данных см. по ссылке R tree index quick start and usage.

space_object:create_index()

object space_object
space_object:create_index(index-name[, index_opts])

Создание индекса.

Обязательным условием является создание индекса для спейса до вставки в спейс кортежей или выборки кортежей из него. Первый созданный индекс, который будет использоваться в качестве первичного индекса, должен быть уникальным.

Параметры:
возвращает:

объект индекса
тип возвращаемого значения:
 

index_object

Возможные ошибки:

  • too many parts
  • index „…“ already exists
  • primary key must be unique

Building or rebuilding a large index will cause occasional yields so that other requests will not be blocked. If the other requests cause an illegal situation such as a duplicate key in a unique index, building or rebuilding such index will fail.

Пример:

-- Create a space --
bands = box.schema.space.create('bands')

-- Specify field names and types --
box.space.bands:format({
    { name = 'id', type = 'unsigned' },
    { name = 'band_name', type = 'string' },
    { name = 'year', type = 'unsigned' }
})

-- Create a primary index --
box.space.bands:create_index('primary', { parts = { 'id' } })

-- Create a unique secondary index --
box.space.bands:create_index('band', { parts = { 'band_name' } })

-- Create a non-unique secondary index --
box.space.bands:create_index('year', { parts = { { 'year' } }, unique = false })

-- Create a multi-part index --
box.space.bands:create_index('year_band', { parts = { { 'year' }, { 'band_name' } } })

index_opts

object index_opts

Index options that include the index name, type, identifiers of key fields, and so on. These options are passed to the space_object.create_index() method.

Примечание

These options are also passed to index_object:alter().

index_opts.type

The index type.


Type: string
Default: TREE
Possible values: TREE, HASH, RTREE, BITSET
index_opts.id

A unique numeric identifier of the index, which is generated automatically.


Type: number
Default: last index’s ID + 1
index_opts.unique

Specify whether an index may be unique. When true, the index cannot contain the same key value twice.


Type: boolean
Default: true

Пример:

-- Create a non-unique secondary index --
box.space.bands:create_index('year', { parts = { { 'year' } }, unique = false })
index_opts.if_not_exists

Specify whether to swallow an error on an attempt to create an index with a duplicated name.


Type: boolean
Default: false
index_opts.parts

Specify the index’s key parts.


Type: a table of key_part values
Default: {1, ‘unsigned’}

Пример:

-- Create a primary index --
box.space.bands:create_index('primary', { parts = { 'id' } })

-- Create a unique secondary index --
box.space.bands:create_index('band', { parts = { 'band_name' } })

-- Create a non-unique secondary index --
box.space.bands:create_index('year', { parts = { { 'year' } }, unique = false })

-- Create a multi-part index --
box.space.bands:create_index('year_band', { parts = { { 'year' }, { 'band_name' } } })

Примечание

Другой способ объявления оператора parts

Если раньше (до версии 2.7.1) индекс состоял из одной части, содержал дополнительные параметры, например is_nullable или collation, и был описан так:

my_space:create_index('one_part_idx', {parts = {1, 'unsigned', is_nullable=true}})

(с одинарными фигурными скобками), то Tarantool игнорировал эти параметры.

Начиная с версии 2.7.1, при описании индекса можно не указывать дополнительные фигурные скобки, но допускаются оба варианта:

-- с дополнительными фигурными скобками
my_space:create_index('one_part_idx', {parts = {{1, 'unsigned', is_nullable=true}}})

-- без дополнительных фигурных скобок
my_space:create_index('one_part_idx', {parts = {1, 'unsigned', is_nullable=true}})
index_opts.dimension

The RTREE index dimension.


Type: number
Default: 2
index_opts.distance

The RTREE index distance type.


Type: string
Default: euclid
Possible values: euclid, manhattan
index_opts.sequence

Create a generator for indexes using a sequence object. Learn more from specifying a sequence in create_index().


Type: string or number
index_opts.func

Specify the identifier of the functional index function.


Type: string
index_opts.hint

Since: 2.6.1

Specify whether hint optimization is enabled for the TREE index:

  • If true, the index works faster.
  • If false, the index size is reduced by half.

Type: boolean
Default: true
index_opts.bloom_fpr

Vinyl only

Specify the bloom filter’s false positive rate.


Type: number
Default: vinyl.bloom_fpr
index_opts.page_size

Vinyl only

Specify the size of a page used for read and write disk operations.


Type: number
Default: vinyl.page_size
index_opts.range_size

Vinyl only

Specify the default maximum range size (in bytes) for a vinyl index.


Type: number
Default: vinyl.range_size
index_opts.run_count_per_level

Vinyl only

Specify the maximum number of runs per level in the LSM tree.


Type: number
Default: vinyl.run_count_per_level
index_opts.run_size_ratio

Vinyl only

Specify the ratio between the sizes of different levels in the LSM tree.


Type: number
Default: vinyl.run_size_ratio

key_part

object key_part

A descriptor of a single part in a multipart key. A table of parts is passed to the index_opts.parts option.

key_part.field

Specify the field number or name.

Примечание

To create a key part by a field name, you need to specify space_object:format() first.


Type: string or number

Examples: Creating an index using field names and numbers

key_part.type

Specify the field type. If the field type is specified in space_object:format(), key_part.type inherits this value.


Type: string
Default: scalar
Possible values: listed in Indexed field types
key_part.collation

Specify the collation used to compare field values. If the field collation is specified in space_object:format(), key_part.collation inherits this value.


Type: string
Possible values: listed in the box.space._collation system space

Пример:

-- Create a space --
box.schema.space.create('tester')

-- Use the 'unicode' collation --
box.space.tester:create_index('unicode', { parts = { { field = 1,
                                                        type = 'string',
                                                        collation = 'unicode' } } })

-- Use the 'unicode_ci' collation --
box.space.tester:create_index('unicode_ci', { parts = { { field = 1,
                                                        type = 'string',
                                                        collation = 'unicode_ci' } } })

-- Insert test data --
box.space.tester:insert { 'ЕЛЕ' }
box.space.tester:insert { 'елейный' }
box.space.tester:insert { 'ёлка' }

-- Returns nil --
select_unicode = box.space.tester.index.unicode:select({ 'ЁлКа' })
-- Returns 'ёлка' --
select_unicode_ci = box.space.tester.index.unicode_ci:select({ 'ЁлКа' })
key_part.is_nullable

Specify whether nil (or its equivalent such as msgpack.NULL) can be used as a field value. If the is_nullable option is specified in space_object:format(), key_part.is_nullable inherits this value.

You can set this option to true if:

  • the index type is TREE
  • the index is not the primary index

It is also legal to insert nothing at all when using trailing nullable fields. Within indexes, such null values are always treated as equal to other null values and are always treated as less than non-null values. Nulls may appear multiple times even in a unique index.


Type: boolean
Default: false

Пример:

box.space.tester:create_index('I', {unique = true, parts = {{field = 2, type = 'number', is_nullable = true}}})

Предупреждение

It is legal to create multiple indexes for the same field with different is_nullable values or to call space_object:format() with a different is_nullable value from what is used for an index. When there is a contradiction, the rule is: null is illegal unless is_nullable=true for every index and for the space format.

key_part.exclude_null

Since: 2.8.2

Specify whether an index can skip tuples with null at this key part. You can set this option to true if:

  • the index type is TREE
  • the index is not the primary index

If exclude_null is set to true, is_nullable is set to true automatically. Note that this option can be changed dynamically. In this case, the index is rebuilt.

Такие индексы вообще не хранят отфильтрованные кортежи, поэтому индексирование будет выполняться быстрее.


Type: boolean
Default: false
key_part.path

Specify the path string for a map field.


Type: string

See the examples below:

Примеры

Creating an index using field names and numbers

create_index() can use field names or field numbers to define key parts.

Example 1 (field names):

To create a key part by a field name, you need to specify space_object:format() first.

-- Create a primary index --
box.space.bands:create_index('primary', { parts = { 'id' } })

-- Create a unique secondary index --
box.space.bands:create_index('band', { parts = { 'band_name' } })

-- Create a non-unique secondary index --
box.space.bands:create_index('year', { parts = { { 'year' } }, unique = false })

-- Create a multi-part index --
box.space.bands:create_index('year_band', { parts = { { 'year' }, { 'band_name' } } })

Example 2 (field numbers):

-- Create a primary index --
box.space.bands:create_index('primary', { parts = { 1 } })

-- Create a unique secondary index --
box.space.bands:create_index('band', { parts = { 2 } })

-- Create a non-unique secondary index --
box.space.bands:create_index('year', { parts = { { 3 } }, unique = false })

-- Create a multi-part index --
box.space.bands:create_index('year_band', { parts = { 3, 2 } })

Создание индекса с использованием пути для полей с ассоциативными массивами (индексы по пути JSON)

Чтобы создать индекс для поля, которое представляет собой ассоциативный массив (строка с путем и скалярное значение), укажите строку c путем во время создания индекса:

parts = {field-number, 'data-type', path = 'path-name'}

Тип индекса должен быть TREE или HASH, а содержимое поля — всегда ассоциативный массив с одним и тем же путем.

Пример 1 — Простое использование пути:

box.schema.space.create('space1')
box.space.space1:create_index('primary', { parts = { { field = 1,
                                                       type = 'scalar',
                                                       path = 'age' } } })
box.space.space1:insert({ { age = 44 } })
box.space.space1:select(44)

Пример 2 — для большей наглядности используем path вместе с format() и JSON-синтаксисом:

box.schema.space.create('space2')
box.space.space2:format({ { 'id', 'unsigned' }, { 'data', 'map' } })
box.space.space2:create_index('info', { parts = { { 'data.full_name["firstname"]', 'str' },
                                                  { 'data.full_name["surname"]', 'str' } } })
box.space.space2:insert({ 1, { full_name = { firstname = 'John', surname = 'Doe' } } })
box.space.space2:select { 'John' }

Создание индекса по массивам (multikey) с использованием опции path с символом [*]

Строка в параметре пути может содержать символ [*], который называется заменителем индекса массива. Описанные так индексы используются для JSON-документов, у которых одинаковая структура.

Например, при создании индекса по полю №2 для документа со строками, который будет начинаться с {'data': [{'name': '...'}, {'name': '...'}], раздел parts в запросе на создание индекса будет выглядеть так:

parts = {{field = 2, type = 'str', path = 'data[*].name'}}

Тогда кортежи с именами можно быстро получить с помощью index_object:select({key-value}).

A single field can have multiple keys, as in this example which retrieves the same tuple twice because there are two keys „A“ and „B“ which both match the request:

my_space = box.schema.space.create('json_documents')
my_space:create_index('primary')
multikey_index = my_space:create_index('multikey', {parts = {{field = 2, type = 'str', path = 'data[*].name'}}})
my_space:insert({1,
         {data = {{name = 'A'},
                  {name = 'B'}},
          extra_field = 1}})
multikey_index:select({''}, {iterator = 'GE'})

Результат выборки будет выглядеть так:

tarantool> multikey_index:select({''},{iterator='GE'})
---
- - [1, {'data': [{'name': 'A'}, {'name': 'B'}], 'extra_field': 1}]
- [1, {'data': [{'name': 'A'}, {'name': 'B'}], 'extra_field': 1}]
...

The following restrictions exist:

  • символ [*] должен стоять отдельно или в конце имени в пути.
  • символ [*] не должен повторяться в пути.
  • Если в индексе есть путь с x[*], то в никаком другом индексе не может быть пути с x.компонентом,
  • [*] нельзя указывать в пути первичного ключа.
  • Если индекс должен быть уникальным (unique=true) и в нем есть путь с символом [*], то запрещается использовать дублирующиеся ключи в разных кортежах, но в в одном кортеже можно использовать дублирующиеся ключи.
  • Структура значения поля должна соответствовать стуктуре, заданной в определении пути, или значение поля должно быть nil (nil не индексируется).
  • В спейсе с индексами по массивам можно хранить не более ~8000 элементов, проиндексированных таким образом.

Создание функционального индекса

Функциональные индексы — это индексы, которые вызывают пользовательскую функцию для формирования ключа индекса, в отличие от других типов индексов, где ключ формирует сам Tarantool. Функциональные индексы используют для сжатия, усечения или реверсирования или любого другого изменения индекса по желанию пользователя.

Ниже приведены рекомендации по созданию функциональных индексов:

  • The function definition must expect a tuple, which has the contents of fields at the time a data-change request happens, and must return a tuple, which has the contents that will be put in the index.
  • The create_index definition must include the specification of all key parts, and the custom function must return a table that has the same number of key parts with the same types.
  • Спейс должен быть на движке memtx.
  • Функция должна быть персистентной и детерминированной (см. Создание функции с телом).
  • Части ключа не должны зависеть от JSON-путей.
  • Функция должна получать доступ к значениям частей ключа по индексу, а не по имени поля.
  • Функциональные индексы не должны быть по первичному ключу.
  • Нельзя изменить ни функциональные индексы, ни функцию, если она используется для индекса, то есть единственный способ изменить их — это удалить индекс и создать его заново.
  • Только функции, запущенные из песочницы, могут использоваться в функциональных индексах.

Пример:

Функция может создать ключ, используя только первую букву строкового поля.

  1. Создайте спейс. В спейсе должно быть поле с первичным ключом, которое не будет полем для функционального индекса:

    box.schema.space.create('tester')
box.space.tester:create_index('i', { parts = { { field = 1, type = 'string' } } })

  2. Создайте функцию. Функция принимает кортеж. В этом примере она работает на кортеже tuple[2], поскольку источник ключа — поле номер 2, в которое мы вставляем данные. Используйте string.sub() из модуля string, чтобы получить первый символ:

    function_code = [[function(tuple) return {string.sub(tuple[2],1,1)} end]]

  3. Сделайте функцию персистентной с помощью box.schema.create:

    box.schema.func.create('my_func',
        { body = function_code, is_deterministic = true, is_sandboxed = true })

  4. Create a functional index. Specify the fields whose values will be passed to the function. Specify the function:

    box.space.tester:create_index('func_index', { parts = { { field = 1, type = 'string' } },
                                              func = 'my_func' })

  5. Insert a few tuples. Select using only the first letter, it will work because that is the key. Or, select using the same function as was used for insertion:

    box.space.tester:insert({ 'a', 'wombat' })
box.space.tester:insert({ 'b', 'rabbit' })
box.space.tester.index.func_index:select('w')
box.space.tester.index.func_index:select(box.func.my_func:call({ { 'tester', 'wombat' } }))

    Результаты двух запросов select будут выглядеть так:

    tarantool> box.space.tester.index.func_index:select('w')
---
- - ['a', 'wombat']
...
tarantool> box.space.tester.index.func_index:select(box.func.my_func:call({{'tester','wombat'}}));
---
- - ['a', 'wombat']
...

Вот пример кода полностью:

box.schema.space.create('tester')
box.space.tester:create_index('i', { parts = { { field = 1, type = 'string' } } })
function_code = [[function(tuple) return {string.sub(tuple[2],1,1)} end]]
box.schema.func.create('my_func',
        { body = function_code, is_deterministic = true, is_sandboxed = true })
box.space.tester:create_index('func_index', { parts = { { field = 1, type = 'string' } },
                                              func = 'my_func' })
box.space.tester:insert({ 'a', 'wombat' })
box.space.tester:insert({ 'b', 'rabbit' })
box.space.tester.index.func_index:select('w')
box.space.tester.index.func_index:select(box.func.my_func:call({ { 'tester', 'wombat' } }))

Функции для функциональных индексов могут возвращать множество ключей. Такие функции называют «мультиключевыми» (multikey).

To create a multikey function, the options of box.schema.func.create() must include is_multikey = true. The return value must be a table of tuples. If a multikey function returns N tuples, then N keys will be added to the index.

Пример:

tester = box.schema.space.create('withdata')
tester:format({ { name = 'name', type = 'string' },
                { name = 'address', type = 'string' } })
name_index = tester:create_index('name', { parts = { { field = 1, type = 'string' } } })
function_code = [[function(tuple)
       local address = string.split(tuple[2])
       local ret = {}
       for _, v in pairs(address) do
         table.insert(ret, {utf8.upper(v)})
       end
       return ret
     end]]
box.schema.func.create('address',
        { body = function_code,
          is_deterministic = true,
          is_sandboxed = true,
          is_multikey = true })
addr_index = tester:create_index('addr', { unique = false,
                                           func = 'address',
                                           parts = { { field = 1, type = 'string',
                                                  collation = 'unicode_ci' } } })
tester:insert({ "James", "SIS Building Lambeth London UK" })
tester:insert({ "Sherlock", "221B Baker St Marylebone London NW1 6XE UK" })
addr_index:select('Uk')

index_object.unique

object index_object
index_object.unique

true if the index is unique, false if the index is not unique.

тип возвращаемого значения:
 boolean (логический)

See also: index_opts.unique

index_object.type

object index_object
index_object.type

The index type.

Rtype:string

See also: index_opts.type

index_object:parts

object index_object
index_object.parts

The index’s key parts.

тип возвращаемого значения:
 таблица

See also: index_opts.parts

index_object:pairs()

object index_object
index_object:pairs([key[, {iterator = iterator-type}]])

Search for a tuple or a set of tuples via the given index, and allow iterating over one tuple at a time. To search by the primary index in the specified space, use the space_object:pairs() method.

Параметр key (ключ) задает, что именно должно совпадать в индексе.

Примечание

key используется в поиске только первого совпадения. Не стоит ожидать, что все подобранные кортежи будут содержать этот ключ.

Параметр iterator (итератор) задает правило для совпадений и упорядочивания. Различные типы индексов поддерживают различные итераторы. Например, TREE-индекс поддерживает строгий порядок ключей и может вернуть все кортежи в порядке по возрастанию или по убыванию, начиная с указанного ключа. Однако другие типы индексов не поддерживают упорядочивание.

To understand consistency of tuples returned by an iterator, it’s essential to know the principles of the Tarantool transaction processing subsystem. An iterator in Tarantool does not own a consistent read view. Instead, each procedure is granted exclusive access to all tuples and spaces until there is a «context switch»: which may happen due to the implicit yield rules, or by an explicit call to fiber.yield. When the execution flow returns to the yielded procedure, the data set could have changed significantly. Iteration, resumed after a yield point, does not preserve the read view, but continues with the new content of the database. The tutorial Indexed pattern search shows one way that iterators and yields can be used together.

For information about iterators“ internal structures, see the «Lua Functional library» documentation.

Параметры:
  • index_object (index_object) – ссылка на объект.
  • key (scalar/table) – value to be matched against the index key, which may be multi-part.
  • iterator – as defined in tables below. The default iterator type is „EQ“.
  • after – a tuple or the position of a tuple (tuple_pos) after which pairs starts the search. You can pass an empty string or box.NULL to this option to start the search from the first tuple.
возвращает:

The iterator, which can be used in a for/end loop or with totable().

Возможные ошибки:

  • no such space
  • wrong type
  • selected iteration type is not supported for the index type
  • key is not supported for the iteration type
  • iterator position is invalid

Факторы сложности Размер индекса, тип индекса; количество кортежей, к которым получен доступ.

Значение искомого ключа может представлять собой число (например, 1234), строку (например, 'abcd') или таблицу из чисел и строк (например, {1234, 'abcd'}). Каждая часть ключа будет сопоставляться с каждой частью ключа в индексе.

Найденные кортежи будут упорядочены по значению ключа в индексе или по хешу значения ключа, если тип индекса – „hash“. Если индекс не уникален, то дубликаты будут упорядочены во вторую очередь по первичному значению ключа. Порядок будет обратным, если тип итератора – „LT“, „LE“ или „REQ“.

Типы итераторов для TREE-индексов

Тип итератора Аргументы Описание
box.index.EQ или „EQ“ искомое значение Оператором сравнения будет „==“ (равно). Если ключ индекса равен искомому значению, получим совпадение. Найденные кортежи упорядочены по возрастанию по ключу индекса. Этот тип используется по умолчанию.
box.index.REQ или „REQ“ искомое значение Совпадения находятся таким же образом, что и для box.index.EQ. Разница только в том, что найденные кортежи упорядочены по ключу индекса по убыванию, а не по возрастанию.
box.index.GT или „GT“ искомое значение Оператором сравнения будет „>“ (больше чем). Если ключ индекса больше, чем искомое значение, получим совпадение. Найденные кортежи упорядочены по возрастанию по ключу индекса.
box.index.GE или „GE“ искомое значение Оператором сравнения будет „>=“ (больше или равен). Если ключ индекса больше искомого значения или равен ему, получим совпадение. Найденные кортежи упорядочены по возрастанию по ключу индекса.
box.index.ALL или „ALL“ искомое значение Как для box.index.GE.
box.index.LT или „LT“ искомое значение Оператором сравнения будет „<“ (меньше чем). Если ключ индекса меньше искомого значения, получим совпадение. Найденные кортежи упорядочены по убыванию по ключу индекса.
box.index.LE или „LE“ искомое значение Оператором сравнения будет „<=“ (меньше или равен). Если ключ индекса меньше искомого значения или равен ему, получим совпадение. Найденные кортежи упорядочены по убыванию по ключу индекса.

Неофициально можно сказать, что поиск с помощью TREE-индексов пользователи обычно считают интуитивно понятным при условии, что нет нулевых значений и отсутствующих частей. Формально же логика заключается в следующем. Ключ поиска состоит из нуля или более частей, например, {}, {1,2,3},{1,nil,3}. Ключ индекса состоит из одной или более частей, например, {1}, {1,2,3},{1,2,3}. Ключ поиска может содержать нулевое значение nil (но не msgpack.NULL, этот тип не будет правильным). Ключ индекса не может содержать nil или msgpack.NULL, хотя в последующих версиях правила работы Tarantool будут другие – поведение поиска с nil может измениться. Возможные итераторы: LT, LE, EQ, REQ, GE, GT. Считается, что ключ поиска соответствует ключу индекса, если следующие операторы, которые представляют собой псевдокод для операции сопоставления, возвращают TRUE.

If (number-of-search-key-parts > number-of-index-key-parts) return ERROR
If (number-of-search-key-parts == 0) return TRUE
for (i = 1; ; ++i)
{
  if (i > number-of-search-key-parts) OR (search-key-part[i] is nil)
  {
    if (iterator is LT or GT) return FALSE
    return TRUE
  }
  if (type of search-key-part[i] is not compatible with type of index-key-part[i])
  {
    return ERROR
  }
  if (search-key-part[i] == index-key-part[i])
  {
    continue
  }
  if (search-key-part[i] > index-key-part[i])
  {
    if (iterator is EQ or REQ or LE or LT) return FALSE
    return TRUE
  }
  if (search-key-part[i] < index-key-part[i])
  {
    if (iterator is EQ or REQ or GE or GT) return FALSE
    return TRUE
  }
}

Типы итераторов для HASH-индексов

Тип возвращаемого значения Аргументы Описание
box.index.ALL нет Все ключи индекса являются совпадениями. Найденные кортежи упорядочены по возрастанию по хешу ключа индекса, который будет выглядеть случайным.
box.index.EQ или „EQ“ искомое значение Оператором сравнения будет „==“ (равный). Если ключ индекса равен искомому значению, получим совпадение. Количество найденных кортежей будет 0 или 1. Этот тип используется по умолчанию.

Типы итераторов для BITSET-индексов

Тип возвращаемого значения Аргументы Описание
box.index.ALL или „ALL“ нет Все ключи индекса являются совпадениями. Найденные кортежи упорядочены по положению в спейсе.
box.index.EQ или „EQ“ значение bitset (битовое множество) Если ключ индекса равен искомому значению, получим совпадение. Найденные кортежи упорядочены по положению в спейсе. Этот тип используется по умолчанию.
box.index.BITS_ALL_SET значение bitset (битовое множество) Если все биты, которые равны 1 в битовом множестве, также равны 1 в ключе индекса, получим совпадение. Найденные кортежи упорядочены по положению в спейсе.
box.index.BITS_ANY_SET значение bitset (битовое множество) Если один из битов, которые равны 1 в битовом множестве, также равен 1 в ключе индекса, получим совпадение. Найденные кортежи упорядочены по положению в спейсе.
box.index.BITS_ALL_NOT_SET значение bitset (битовое множество) Если все биты, которые равны 1 в битовом множестве, равны 0 в ключе индекса, получим совпадение. Найденные кортежи упорядочены по положению в спейсе.

Типы итераторов для RTREE-индексов

Тип возвращаемого значения Аргументы Описание
box.index.ALL или „ALL“ нет Все ключи являются совпадениями. Найденные кортежи упорядочены по положению в спейсе.
box.index.EQ или „EQ“ искомое значение Если все точки прямоугольника-или-параллелепипеда, определенные искомым значением, совпадают с точками прямоугольника-или-параллелепипеда, определенного ключом индекса, получим совпадение. Найденные кортежи упорядочены по положению в спейсе. «Прямоугольник-или-параллелепипед» означает «прямоугольник-или-параллелепипед, как описано в разделе о RTREE». Этот тип используется по умолчанию.
box.index.GT или „GT“ искомое значение Если все точки прямоугольника-или-параллелепипеда, определенные искомым значением, находятся в пределах прямоугольника-или-параллелепипеда, определенного ключом индекса, получим совпадение. Найденные кортежи упорядочены по положению в спейсе.
box.index.GE или „GE“ искомое значение Если все точки прямоугольника-или-параллелепипеда, определенные искомым значением, находятся в пределах прямоугольника-или-параллелепипеда, определенного ключом индекса, или рядом с ним, получим совпадение. Найденные кортежи упорядочены по положению в спейсе.
box.index.LT или „LT“ искомое значение Если все точки прямоугольника-или-параллелепипеда, определенные ключом индекса, находятся в пределах прямоугольника-или-параллелепипеда, определенного искомым значением, получим совпадение. Найденные кортежи упорядочены по положению в спейсе.
box.index.LE или „LE“ искомое значение Если все точки прямоугольника-или-параллелепипеда, определенные ключом индекса, находятся в пределах прямоугольника-или-параллелепипеда, определенного искомым значением, или рядом с ним, получим совпадение. Найденные кортежи упорядочены по положению в спейсе.
box.index.OVERLAPS или „OVERLAPS“ искомое значение Если некоторые точки прямоугольника-или-параллелепипеда, определенные искомым значением, находятся в пределах прямоугольника-или-параллелепипеда, определенного ключом индекса, получим совпадение. Найденные кортежи упорядочены по положению в спейсе.
box.index.NEIGHBOR или „NEIGHBOR“ искомое значение Если некоторые точки прямоугольника-или-параллелепипеда, определенные ключом, находятся в пределах, определенных ключом индекса, или рядом с ним, получим совпадение. Найденные кортежи упорядочены следующим образом: сначала ближайший сосед.

Examples:

Below are few examples of using pairs with different parameters. To try out these examples, you need to bootstrap a Tarantool instance as described in Using data operations.

-- Insert test data --
tarantool> bands:insert{1, 'Roxette', 1986}
           bands:insert{2, 'Scorpions', 1965}
           bands:insert{3, 'Ace of Base', 1987}
           bands:insert{4, 'The Beatles', 1960}
           bands:insert{5, 'Pink Floyd', 1965}
           bands:insert{6, 'The Rolling Stones', 1962}
           bands:insert{7, 'The Doors', 1965}
           bands:insert{8, 'Nirvana', 1987}
           bands:insert{9, 'Led Zeppelin', 1968}
           bands:insert{10, 'Queen', 1970}
---
...

-- Select all tuples by the primary index --
tarantool> for _, tuple in bands.index.primary:pairs() do
               print(tuple)
           end
[1, 'Roxette', 1986]
[2, 'Scorpions', 1965]
[3, 'Ace of Base', 1987]
[4, 'The Beatles', 1960]
[5, 'Pink Floyd', 1965]
[6, 'The Rolling Stones', 1962]
[7, 'The Doors', 1965]
[8, 'Nirvana', 1987]
[9, 'Led Zeppelin', 1968]
[10, 'Queen', 1970]
---
...

-- Select all tuples whose secondary key values start with the specified string --
tarantool> for _, tuple in bands.index.band:pairs("The", {iterator = "GE"}) do
             if (string.sub(tuple[2], 1, 3) ~= "The") then break end
             print(tuple)
           end
[4, 'The Beatles', 1960]
[7, 'The Doors', 1965]
[6, 'The Rolling Stones', 1962]
---
...

-- Select all tuples whose secondary key values are between 1965 and 1970 --
tarantool> for _, tuple in bands.index.year:pairs(1965, {iterator = "GE"}) do
             if (tuple[3] > 1970) then break end
             print(tuple)
           end
[2, 'Scorpions', 1965]
[5, 'Pink Floyd', 1965]
[7, 'The Doors', 1965]
[9, 'Led Zeppelin', 1968]
[10, 'Queen', 1970]
---
...

-- Select all tuples after the specified tuple --
tarantool> for _, tuple in bands.index.primary:pairs({}, {after={7, 'The Doors', 1965}}) do
               print(tuple)
           end
[8, 'Nirvana', 1987]
[9, 'Led Zeppelin', 1968]
[10, 'Queen', 1970]
---
...

index_object:select()

object index_object
index_object:select(search-key, options)

Search for a tuple or a set of tuples by the current index. To search by the primary index in the specified space, use the space_object:select() method.

Параметры:
  • index_object (index_object) – ссылка на объект.
  • key (scalar/table) – a value to be matched against the index key, which may be multi-part.
  • options (table/nil) –

    ни один, любой или все следующие параметры:

    • iterator – the iterator type. The default iterator type is „EQ“.
    • limit – the maximum number of tuples.
    • offset – the number of tuples to skip (use this parameter carefully when scanning large data sets).
    • options.after – a tuple or the position of a tuple (tuple_pos) after which select starts the search. You can pass an empty string or box.NULL to this option to start the search from the first tuple.
    • options.fetch_pos – if true, the select method returns the position of the last selected tuple as the second value.

      Примечание

      The after and fetch_pos options are supported for the TREE index only.
возвращает:

This function might return one or two values:

  • The tuples whose fields are equal to the fields of the passed key. If the number of passed fields is less than the number of fields in the current key, then only the passed fields are compared, so select{1,2} matches a tuple whose primary key is {1,2,3}.
  • (Optionally) If options.fetch_pos is set to true, returns a base64-encoded string representing the position of the last selected tuple as the second value. If no tuples are fetched, returns nil.
тип возвращаемого значения:
 
  • массив кортежей
  • (Optionally) string

Предупреждение

Use the offset option carefully when scanning large data sets as it linearly increases the number of scanned tuples and leads to a full space scan. Instead, you can use the after and fetch_pos options.

Examples:

Below are few examples of using select with different parameters. To try out these examples, you need to bootstrap a Tarantool database as described in Using data operations.

-- Insert test data --
box.space.bands:insert { 1, 'Roxette', 1986 }
box.space.bands:insert { 2, 'Scorpions', 1965 }
box.space.bands:insert { 3, 'Ace of Base', 1987 }
box.space.bands:insert { 4, 'The Beatles', 1960 }
box.space.bands:insert { 5, 'Pink Floyd', 1965 }
box.space.bands:insert { 6, 'The Rolling Stones', 1962 }
box.space.bands:insert { 7, 'The Doors', 1965 }
box.space.bands:insert { 8, 'Nirvana', 1987 }
box.space.bands:insert { 9, 'Led Zeppelin', 1968 }
box.space.bands:insert { 10, 'Queen', 1970 }

-- Select a tuple by the specified primary key value --
select_primary = bands.index.primary:select { 1 }
--[[
---
- - [1, 'Roxette', 1986]
...
--]]

-- Select a tuple by the specified secondary key value --
select_secondary = bands.index.band:select { 'The Doors' }
--[[
---
- - [7, 'The Doors', 1965]
...
--]]

-- Select a tuple by the specified multi-part secondary key value --
select_multipart = bands.index.year_band:select { 1960, 'The Beatles' }
--[[
---
- - [4, 'The Beatles', 1960]
...
--]]

-- Select tuples by the specified partial key value --
select_multipart_partial = bands.index.year_band:select { 1965 }
--[[
---
- - [5, 'Pink Floyd', 1965]
  - [2, 'Scorpions', 1965]
  - [7, 'The Doors', 1965]
...
--]]

-- Select maximum 3 tuples by the specified secondary index --
select_limit = bands.index.band:select({}, { limit = 3 })
--[[
---
- - [3, 'Ace of Base', 1987]
  - [9, 'Led Zeppelin', 1968]
  - [8, 'Nirvana', 1987]
...
--]]

-- Select maximum 3 tuples with the key value greater than 1965 --
select_greater = bands.index.year:select({ 1965 }, { iterator = 'GT', limit = 3 })
--[[
---
- - [9, 'Led Zeppelin', 1968]
  - [10, 'Queen', 1970]
  - [1, 'Roxette', 1986]
...
--]]

-- Select maximum 3 tuples after the specified tuple --
select_after_tuple = bands.index.primary:select({}, { after = { 4, 'The Beatles', 1960 }, limit = 3 })
--[[
---
- - [5, 'Pink Floyd', 1965]
  - [6, 'The Rolling Stones', 1962]
  - [7, 'The Doors', 1965]
...
--]]

-- Select first 3 tuples and fetch a last tuple's position --
result, position = bands.index.primary:select({}, { limit = 3, fetch_pos = true })
-- Then, pass this position as the 'after' parameter --
select_after_position = bands.index.primary:select({}, { limit = 3, after = position })
--[[
---
- - [4, 'The Beatles', 1960]
  - [5, 'Pink Floyd', 1965]
  - [6, 'The Rolling Stones', 1962]
...
--]]

Примечание

box.space.имя-спейса.index.имя-индекса:select(...)[1] можно заменить box.space.имя-спейса.index.имя-индекса:get(...). А именно, get можно использовать в качестве удобного сокращения для получения первого кортежа в наборе кортежей, который был бы выведен по запросу select. Однако, если в наборе кортежей больше одного кортежа, get завершится с ошибкой.

index_object:get()

object index_object
index_object:get(key)

Search for a tuple via the given index, as described in the select topic.

Параметры:
возвращает:

кортеж, в котором поля ключа в индексе равны переданным значениям ключа.
тип возвращаемого значения:
 

кортеж

Возможные ошибки:

  • отсутствие такого индекса;
  • неправильный тип;
  • больше одного кортежа подходят.

Факторы сложности: Размер индекса, тип индекса. См. также space_object:get().

Пример:

tarantool> box.space.tester.index.primary:get(2)
---
- [2, 'Music']
...

index_object:min()

object index_object
index_object:min([key])

Поиск минимального значения в указанном индексе.

Параметры:
возвращает:

кортеж для первого ключа в индексе. Если указано необязательное значение ключа key, будет выведен первый ключ, который больше или равен значению ключа key. Начиная с версии Tarantool 2.0.4, index:min(key) не вернет ничего, если индекс не содержит значения key.
тип возвращаемого значения:
 

кортеж

Возможные ошибки:

Факторы сложности: Размер индекса, тип индекса.

Пример:

Below are few examples of using min. To try out these examples, you need to bootstrap a Tarantool database as described in Using data operations.

-- Insert test data --
box.space.bands:insert { 1, 'Roxette', 1986 }
box.space.bands:insert { 2, 'Scorpions', 1965 }
box.space.bands:insert { 3, 'Ace of Base', 1987 }
box.space.bands:insert { 4, 'The Beatles', 1960 }
box.space.bands:insert { 5, 'Pink Floyd', 1965 }
box.space.bands:insert { 6, 'The Rolling Stones', 1962 }
box.space.bands:insert { 7, 'The Doors', 1965 }
box.space.bands:insert { 8, 'Nirvana', 1987 }
box.space.bands:insert { 9, 'Led Zeppelin', 1968 }
box.space.bands:insert { 10, 'Queen', 1970 }

-- Find the minimum value in the specified index
min = box.space.bands.index.year:min()
--[[
---
- [4, 'The Beatles', 1960]
...
--]]

-- Find the minimum value that matches the partial key value
min_partial = box.space.bands.index.year_band:min(1965)
--[[
---
- [5, 'Pink Floyd', 1965]
...
--]]

index_object:max()

object index_object
index_object:max([key])

Поиск максимального значения в указанном индексе.

Параметры:
возвращает:

кортеж для последнего ключа в индексе. Если указано необязательное значение ключа key, будет выведен последний ключ, который меньше или равен значению ключа key. Начиная с версии Tarantool 2.0.4, index:max(key) не возвращает ничего, если индекс не содержит значения key.
тип возвращаемого значения:
 

tuple

Возможные ошибки:

Факторы сложности: размер индекса, тип индекса.

Пример:

Below are few examples of using max. To try out these examples, you need to bootstrap a Tarantool database as described in Using data operations.

-- Insert test data --
box.space.bands:insert { 1, 'Roxette', 1986 }
box.space.bands:insert { 2, 'Scorpions', 1965 }
box.space.bands:insert { 3, 'Ace of Base', 1987 }
box.space.bands:insert { 4, 'The Beatles', 1960 }
box.space.bands:insert { 5, 'Pink Floyd', 1965 }
box.space.bands:insert { 6, 'The Rolling Stones', 1962 }
box.space.bands:insert { 7, 'The Doors', 1965 }
box.space.bands:insert { 8, 'Nirvana', 1987 }
box.space.bands:insert { 9, 'Led Zeppelin', 1968 }
box.space.bands:insert { 10, 'Queen', 1970 }

-- Find the maximum value in the specified index
max = box.space.bands.index.year:max()
--[[
---
- [8, 'Nirvana', 1987]
...
--]]

-- Find the maximum value that matches the partial key value
max_partial = box.space.bands.index.year_band:max(1965)
--[[
---
- [7, 'The Doors', 1965]
...
--]]

index_object:random()

object index_object
index_object:random(seed)

Поиск случайного значения в заданном индексе. Данный метод используется, когда важно получить представление о распределении данных в индексе без необходимости проходить по всему набору данных.

Параметры:
возвращает:

кортеж для случайного ключа в индексе.
тип возвращаемого значения:
 

tuple

Факторы сложности: Размер индекса, тип индекса

Note regarding storage engine: vinyl does not support random().

Пример:

tarantool> box.space.tester.index.secondary:random(1)
---
- ['Beta!', 66, 'This is the second tuple!']
...

index_object:count()

object index_object
index_object:count([key][, iterator])

Итерация по индексу с подсчетом количества кортежей, которые соответствуют паре ключ-значение.

Параметры:
  • index_object (index_object) – ссылка на объект.
  • key (scalar/table) – значения для сопоставления с ключом индекса
  • iterator – метод сопоставления
возвращает:

количество совпадающих кортежей.
тип возвращаемого значения:
 

число

Пример:

Below are few examples of using count. To try out these examples, you need to bootstrap a Tarantool database as described in Using data operations.

-- Insert test data --
box.space.bands:insert { 1, 'Roxette', 1986 }
box.space.bands:insert { 2, 'Scorpions', 1965 }
box.space.bands:insert { 3, 'Ace of Base', 1987 }
box.space.bands:insert { 4, 'The Beatles', 1960 }
box.space.bands:insert { 5, 'Pink Floyd', 1965 }
box.space.bands:insert { 6, 'The Rolling Stones', 1962 }
box.space.bands:insert { 7, 'The Doors', 1965 }
box.space.bands:insert { 8, 'Nirvana', 1987 }
box.space.bands:insert { 9, 'Led Zeppelin', 1968 }
box.space.bands:insert { 10, 'Queen', 1970 }

-- Count the number of tuples that match the full key value
count = box.space.bands.index.year:count(1965)
--[[
---
- 3
...
--]]

-- Count the number of tuples that match the partial key value
count_partial = box.space.bands.index.year_band:count(1965)
--[[
---
- 3
...
--]]

index_object:update()

object index_object
index_object:update(key, {{operator, field_identifier, value}, ...})

Обновление кортежа.

То же, что и box.space…update(), но поиск ключа происходит в этом индексе, вместо первичного. Данный индекс должен быть уникальным.

Параметры:
  • index_object (index_object) – ссылка на объект.
  • key (scalar/table) – значения для сопоставления с ключом индекса
  • operator (string) – тип операции, представленный строкой
  • field_identifier (field-or-string) – к какому полю применяется операция. Номер поля может быть отрицательным, что означает, что позиция рассчитывается с конца кортежа. (#кортеж + отрицательный номер поля + 1)
  • value (lua_value) – какое значение применяется
возвращает:
  • обновленный кортеж
  • nil, если ключ не найден
тип возвращаемого значения:
 

tuple или nil

Начиная с версии Tarantool 2.3 кортеж можно обновить с помощью JSON-путей.

index_object:delete()

object index_object
index_object:delete(key)

Удаление кортежа по ключу.

То же, что и box.space…delete(), но поиск ключа происходит в этом индексе, вместо первичного. Данный индекс должен быть уникальным.

Параметры:
возвращает:

удаленный кортеж.
тип возвращаемого значения:
 

кортеж

Note regarding storage engine: vinyl will return nil, rather than the deleted tuple.

index_object:alter()

object index_object
index_object:alter({options})

Изменение индекса. В определенных обстоятельствах можно изменять некоторые характеристики индекса, например тип, параметры последовательности и определение его уникальности. Тем не менее, это обычно приводит к перестроению спейса за исключением простого случая, когда значение флага is_nullable меняется с false на true.

Параметры:
возвращает:

nil

Возможные ошибки:

  • index does not exist
  • the primary-key index cannot be changed to {unique = false}

Примечание

Vinyl does not support alter() of a primary-key index unless the space is empty.

Пример 1:

Можно добавлять и удалять поля, которые составляют первичный индекс:

tarantool> s = box.schema.create_space('test')
---
...
tarantool> i = s:create_index('i', {parts = {{field = 1, type = 'unsigned'}}})
---
...
tarantool> s:insert({1, 2})
---
- [1, 2]
...
tarantool> i:select()
---
- - [1, 2]
...
tarantool> i:alter({parts = {{field = 1, type = 'unsigned'}, {field = 2, type = 'unsigned'}}})
---
...
tarantool> s:insert({1, 't'})
---
- error: 'Tuple field 2 type does not match one required by operation: expected unsigned'
...

Пример 2:

Можно изменять опции индекса для спейсов как в memtx’е, так и в vinyl’е:

tarantool> box.space.space55.index.primary:alter({type = 'HASH'})
---
...

tarantool> box.space.vinyl_space.index.i:alter({page_size=4096})
---
...

index_object:drop()

object index_object
index_object:drop()

Удаление индекса. Побочный эффект удаления первичного индекса – все кортежи удалятся.

Параметры:
возвращает:

nil.

Возможные ошибки:

  • индекс не существует,
  • первичный индекс невозможно удалить, если существует вторичный индекс.

Пример:

tarantool> box.space.space55.index.primary:drop()
---
...

index_object:rename()

object index_object
index_object:rename(index-name)

Переименование индекса.

Параметры:
возвращает:

nil

Возможные ошибки: index_object не существует.

Пример:

tarantool> box.space.space55.index.primary:rename('secondary')
---
...

Факторы сложности: Размер индекса, тип индекса, количество кортежей, к которым получен доступ.

index_object:bsize()

object index_object
index_object:bsize()

Выдача общего количества байтов, занятых индексом.

Параметры:
возвращает:

количество байтов
тип возвращаемого значения:
 

number

index_object:stat()

object index_object
index_object:stat()

Получение статистики о предпринятых действиях, которые влияют на индекс.

Используется с движком базы данных vinyl.

Подробные данные в выводе index_object:stat():

  • index_object:stat().latency содержит отметки времени в процентах;
  • index_object:stat().bytes содержит общее количество байтов;
  • index_object:stat().disk.rows содержит примерное количество кортежей в каждом диапазоне;
  • index_object:stat().disk.statement содержит количество вставок, обновлений, обновлений и вставок, удалений (inserts|updates|upserts|deletes);
  • index_object:stat().disk.compaction содержит количество слияний и их объем;
  • index_object:stat().disk.dump содержит количество дампов и их объем;
  • index_object:stat().disk.iterator.bloom содержит количество совпадений и несовпадений по фильтрами Блума;
  • index_object:stat().disk.pages содержит размер в страницах;
  • index_object:stat().disk.last_level содержит объем данных на последнем уровне LSM-дерева;
  • index_object:stat().cache.evict содержит количество освобождений кэша;
  • index_object:stat().range_size содержит максимальное количество байтов в диапазоне;
  • index_object:stat().dumps_per_compaction содержит среднее число дампов, которое необходимо для запуска значительного слияния в любом диапазоне LSM-дерева.

Summary index statistics are also available via box.stat.vinyl().

Параметры:
возвращает:

статистические данные
тип возвращаемого значения:
 

таблица

index_object:compact()

object index_object
index_object:compact()

Удаление неиспользуемого пространства индекса. Для движка базы данных memtx метод бесполезен; index_object:compact() используется только для движка vinyl. Например, на движке vinyl при удалении кортежа память не возвращается незамедлительно. Существует планировщик автоматического восстановления ресурсов на основании таких факторов, как форма LSM-дерева и усложнение, как описано в разделе Хранение данных с помощью vinyl, поэтому выполнять index_object:compact() вручную необходимости нет.

возвращает:nil (Tarantool возвращает нулевое значение сразу же, не ожидая завершения слияния)

index_object:tuple_pos()

object index_object
index_object:tuple_pos(tuple)

Return a tuple’s position for an index. This value can be passed to the after option of the select and pairs methods:

Note that tuple_pos does not work with functional and multikey indexes.

Параметры:
Return:

a tuple’s position in a space
Rtype:

base64-encoded string

Example:

To try out this example, you need to bootstrap a Tarantool instance as described in Using data operations.

-- Insert test data --
tarantool> bands:insert{1, 'Roxette', 1986}
           bands:insert{2, 'Scorpions', 1965}
           bands:insert{3, 'Ace of Base', 1987}
           bands:insert{4, 'The Beatles', 1960}
           bands:insert{5, 'Pink Floyd', 1965}
           bands:insert{6, 'The Rolling Stones', 1962}
---
...

-- Get a tuple's position --
tarantool> position = bands.index.primary:tuple_pos({3, 'Ace of Base', 1987})
---
...
-- Pass the tuple's position as the 'after' parameter --
tarantool> bands:select({}, {limit = 3, after = position})
---
- - [4, 'The Beatles', 1960]
  - [5, 'Pink Floyd', 1965]
  - [6, 'The Rolling Stones', 1962]
...

index_object extensions

Пользователи могут сами определять любые желаемые функции и связывать их с индексами: фактически они могут создавать собственные методы для работы с индексом. Это можно сделать так:

  1. создать Lua-функцию,
  2. добавить имя функции в заданную глобальную переменную с типом «таблица» (table),
  3. впоследствии в любое время, пока работает сервер, вызвать функцию с помощью объект_индекса:имя-функции([параметры]).

Есть три заданные глобальные переменные:

Можно также сделать задаваемый пользователем метод доступным только для одного индекса путем вызова getmetatable(объект_индекса) и последующего добавления имени функции в метатаблицу.

Example 1:

The example below shows how to extend all memtx indexes with the custom function:

box.schema.space.create('tester1', { engine = 'memtx' })
box.space.tester1:create_index('index1')
global_counter = 5

-- Create a custom function.
function increase_global_counter()
    global_counter = global_counter + 1
end

-- Extend all memtx indexes with the created function.
box.schema.memtx_index_mt.increase_global_counter = increase_global_counter

-- Call the 'increase_global_counter' function on 'index1'
-- to change the 'global_counter' value from 5 to 6.
box.space.tester1.index.index1:increase_global_counter()

Example 2:

The example below shows how to extend the specified index with the custom function with parameters:

box.schema.space.create('tester2', { engine = 'memtx', id = 1000 })
box.space.tester2:create_index('index2')
local_counter = 0

-- Create a custom function.
function increase_local_counter(i_arg, param)
    local_counter = local_counter + param + i_arg.space_id
end

-- Extend only the 'index2' index with the created function.
box.schema.memtx_index_mt.increase_local_counter = increase_local_counter
meta = getmetatable(box.space.tester2.index.index2)
meta.increase_local_counter = increase_local_counter

-- Call the 'increase_local_counter' function on 'index2'
-- to change the 'local_counter' value from 0 to 1005.
box.space.tester2.index.index2:increase_local_counter(5)

Вложенный модуль box.info

The box.info submodule provides access to information about a running Tarantool instance. Below is a list of all box.info functions and members.

Имя Назначение
box.info() Get all keys and values provided by the box.info submodule
box.info.cluster Information about the cluster to which the current instance belongs
box.info.config The instance’s state in regard to configuration
box.info.election The current state of this replica set node in regard to leader election
box.info.gc() Get information about the Tarantool garbage collector
box.info.hostname The hostname that identifies a machine the current instance is running on
box.info.id A numeric identifier of the current instance within the replica set
box.info.listen A real address to which an instance is bound
box.info.lsn A log sequence number (LSN) for the latest entry in the instance’s write-ahead log (WAL)
box.info.memory() Get information about memory usage for the current instance
box.info.name The name of the current instance
box.info.package The package name
box.info.pid Get a process ID of the current instance
box.info.replicaset Information about the replica set to which the current instance belongs
box.info.replication Statistics for all instances in the replica set
box.info.replication_anon() List all the anonymous replicas following the instance
box.info.ro The current mode of the instance (writable or read-only)
box.info.ro_reason The reason why the current instance is read-only
box.info.schema_version The database schema version
box.info.signature The sum of all lsn values from each vector clock for all instances in the replica set
box.info.sql Get information about the cache for all SQL prepared statements
box.info.status The current state of the instance
box.info.synchro The current state of synchronous replication
box.info.uptime The number of seconds since the instance started
box.info.uuid A globally unique identifier of the current instance
box.info.vclock A table with the vclock values of all instances in a replica set which have made data changes
box.info.version The Tarantool version
box.info.vinyl() (Deprecated) Get runtime statistics for the vinyl storage engine

box.info()

box.info()

Get all keys and values provided by the box.info submodule. Since box.info contents are dynamic, it’s not possible to iterate over keys with the Lua pairs() function. For this purpose, box.info() builds and returns a Lua table with all keys and values provided in the submodule.

возвращает:ключи и значения во вложенном модуле
тип возвращаемого значения:
 таблица

Example

Данный пример приводится для набора со схемой мастер-реплика, который включает в себя один мастер-экземпляр и один реплика-экземпляр. Запрос был отправлен с реплики-экземпляра.

sharded_cluster_crud:storage-a-002> box.info()
---
- version: 3.2.0-entrypoint-218-gf8d77dbec
  id: 2
  ro: true
  uuid: 5a879b0e-9b53-4053-980a-be1a39ad1166
  pid: 12059
  replicaset:
    uuid: 90dc4d6c-3f7d-45e5-aa5a-55903b0a79c9
    name: storage-a
  schema_version: 87
  listen: 127.0.0.1:3303
  replication_anon:
    count: 0
  replication:
    1:
      id: 1
      uuid: ffb1b8bb-d59f-4eee-ad3e-91058e6f5486
      lsn: 1092
      upstream:
        status: follow
        idle: 0.99728900000082
        peer: replicator@127.0.0.1:3302
        lag: 0.00025296211242676
      name: storage-a-001
      downstream:
        status: follow
        idle: 0.18575600000077
        vclock: {1: 1092}
        lag: 0
    2:
      id: 2
      uuid: 5a879b0e-9b53-4053-980a-be1a39ad1166
      lsn: 0
      name: storage-a-002
  package: Tarantool
  hostname: demo.example.com
  election:
    state: follower
    vote: 0
    leader: 0
    term: 1
  signature: 1092
  synchro:
    queue:
      owner: 0
      confirm_lag: 0
      term: 0
      age: 0
      len: 0
      busy: false
    quorum: 2
  status: running
  sql: []
  vclock: {1: 1092}
  uptime: 229
  lsn: 0
  vinyl: []
  ro_reason: config
  memory: []
  gc: []
  cluster:
    name: null
  name: storage-a-002
  config:
    status: ready
    meta:
      last: &0 []
      active: *0
    alerts: []
...

box.info.cluster

box.info.cluster

Information about the cluster to which the current instance belongs. The returned table contains the following fields:

  • name – the cluster name

See also: compat.box_info_cluster_meaning

Rtype:table

box.info.config

box.info.config

Since: 3.2.0

The instance’s state in regard to configuration. Note that box.info.config returns the instance’s state obtained using config:info(„v2“).

Rtype:table

Example

sharded_cluster_crud:storage-a-002> box.info.config
---
- status: ready
  meta:
    last: &0 []
    active: *0
  alerts: []
...

box.info.election

box.info.election

Since: 2.6.1

The current state of this replica set node in regard to leader election. The following information is provided:

  • state – the election state (mode) of the node. Possible values are leader, follower, or candidate. For more details, refer to description of the leader election process. When replication.failover is set to election, the node is writable only in the leader state.
  • term – the current election term.
  • vote – the ID of a node the current node votes for. If the value is 0, it means the node hasn’t voted in the current term yet.
  • leader – a leader node ID in the current term. If the value is 0, it means the node doesn’t know which node is the leader in the current term.
  • leader_name – a leader name. Returns nil if there is no leader in a cluster or box.NULL if a leader does not have a name. Since version 3.0.0.
  • leader_idle – time in seconds since the last interaction with the known leader. Since version 2.10.0.

Примечание

IDs in the box.info.election output are the replica IDs visible in the box.info.id output on each node and in the _cluster space.

Пример:

auto_leader:instance001> box.info.election
---
- leader_idle: 0
  leader_name: instance001
  state: leader
  vote: 2
  term: 3
  leader: 2
...

See also: Master-replica: automated failover.

box.info.gc()

box.info.gc()

Get information about the Tarantool garbage collector. The garbage collector compares vclock (vector clock) values of users and checkpoints, so a look at box.info.gc() may show why the garbage collector has not removed old WAL files, or show what it may soon remove.

  • consumers – a list of users whose requests might affect the garbage collector.
  • checkpoints – a list of preserved checkpoints.
  • checkpoints[n].references – a list of references to a checkpoint.
  • checkpoints[n].vclock – a checkpoint’s vclock value.
  • checkpoints[n].signature – a sum of a checkpoint’s vclock’s components.
  • checkpoint_is_in_progress – true if a checkpoint is in progress, otherwise false
  • vclock – the garbage collector’s vclock.
  • signature – the sum of the garbage collector’s checkpoint’s components.
  • wal_retention_vclock – a vclock value of the oldest write-ahead log file protected from removing by the garbage collector by using the wal.retention_period option.

box.info.hostname

box.info.hostname

Since: 3.2.0

The hostname that identifies a machine the current instance is running on.

Rtype:string

box.info.id

box.info.id

A numeric identifier of the current instance within the replica set. This value corresponds to replication[{n}].id. Learn more in box.info.replication.

Rtype:number

box.info.listen

box.info.listen

Since: 2.4.1

A real address to which an instance is bound. If an instance does not listen to anything, box.info.listen is nil.

To learn how to configure URIs used to listen for incoming requests, see iproto.listen.

Rtype:string

Example

sharded_cluster_crud:storage-a-002> box.info.listen
---
- 127.0.0.1:3303
...

box.info.lsn

box.info.lsn

A log sequence number (LSN) for the latest entry in the instance’s write-ahead log (WAL). This value corresponds to `replication[{n}].lsn. Learn more in box.info.replication.

Rtype:number

box.info.memory()

box.info.memory()

Get information about memory usage for the current instance.

Примечание

Чтобы получить представление о подсистеме vinyl’а, используйте box.stat.vinyl().

  • cache – the number of bytes used for caching user data. The memtx storage engine does not require a cache, so in fact this is the number of bytes in the cache for the tuples stored for the vinyl storage engine.
  • data – the number of bytes used for storing user data (the tuples) with the memtx engine and with level 0 of the vinyl engine, without taking memory fragmentation into account.
  • index – the number of bytes used for indexing user data, including memtx and vinyl memory tree extents, the vinyl page index, and the vinyl bloom filters.
  • lua – the number of bytes used for Lua runtime.
  • net – the number of bytes used for network input/output buffers.
  • tx – the number of bytes in use by active transactions. For the vinyl storage engine, this is the total size of all allocated objects (struct txv, struct vy_tx, struct vy_read_interval) and tuples pinned for those objects.

Example

sharded_cluster_crud:storage-a-002> box.info.memory()
---
- cache: 0
  data: 43848
  index: 1130496
  lua: 10516849
  net: 1572864
  tx: 0
...

box.info.name

box.info.name

Since: 3.0.0

The name of the current instance. You can specify the names of instances when configuring a cluster topology.

Rtype:string

Example

sharded_cluster_crud:storage-a-002> box.info.name
---
- storage-a-002
...

box.info.package

box.info.package

The package name. It can be:

  • Tarantool
  • Tarantool Enterprise

See also: tarantool.package, tarantool –version

Rtype:string

box.info.pid

box.info.pid

A process ID of the current instance. You can also get the process ID as follows:

Rtype:number

box.info.replicaset

box.info.replicaset

Since: 3.0.0

Information about the replica set to which the current instance belongs. The returned table contains the following fields:

  • name – the replica set name
  • uuid – the replica set UUID

You can specify the names of replica sets when configuring a cluster topology.

Rtype:table

box.info.replication

box.info.replication

The replication section of box.info() is a table with statistics for all instances in the replica set that the current instance belongs to. To see the example, refer to Monitoring a replica set.

In the following, n is the index number of one table item, for example, replication[1], which has data about server instance number 1, which may or may not be the same as the current instance (the «current instance» is what is responding to box.info).

  • replication[n].id – это короткий числовой идентификатор экземпляра в наборе реплик. Данное значение хранится в системном спейсе box.space._cluster.

  • replication[n].uuid – это глобально-уникальный идентификатор экземпляра. Данное значение хранится в системном спейсе box.space._cluster.

  • replication[n].lsn is the log sequence number (LSN) for the latest entry in instance n’s write-ahead log (WAL).

  • replication[n].name is the instance name. See also: box.info.name.

  • replication[n].upstream appears (is not nil) if the current instance is following or intending to follow instance n, which ordinarily means replication[n].upstream.status = follow, replication[n].upstream.peer = url of instance n which is being followed, replication[n].lag and idle = the instance’s speed, described later. Another way to say this is: replication[n].upstream will appear when replication[n].upstream.peer is not of the current instance, and is not read-only, and was specified in box.cfg{replication={...}}, so it is shown in box.cfg.replication.

  • replication[n].upstream.status is the replication status of the connection with the instance n:

    • connect: an instance is connecting to the master.
    • auth: authentication is being performed.
    • wait_snapshot: an instance is receiving metadata from the master. If join fails with a non-critical error at this stage (for example, ER_READONLY, ER_ACCESS_DENIED, or a network-related issue), an instance tries to find a new master to join.
    • fetch_snapshot: an instance is receiving data from the master’s .snap files.
    • final_join: an instance is receiving new data added during fetch_snapshot.
    • sync: the master and replica are synchronizing to have the same data.
    • follow: the current instance’s role is replica. This means that the instance is read-only or acts as a replica for this remote peer in master-master configuration. The instance is receiving or able to receive data from the instance n’s (upstream) master.
    • stopped: replication is stopped due to a replication error (for example, duplicate key).
    • disconnected: an instance is not connected to the replica set (for example, due to network issues, not replication errors).

    Learn more from Replication stages.

  • replication[n].upstream.idle is the time (in seconds) since the last event was received. This is the primary indicator of replication health. Learn more from Monitoring a replica set.

  • replication[n].upstream.lag is the time difference between the local time of instance n, recorded when the event was received, and the local time at another master recorded when the event was written to the write-ahead log on that master. Learn more from Monitoring a replica set.

  • replication[n].upstream.message contains an error message in case of a degraded state; otherwise, it is nil.

  • replication[n].downstream appears (is not nil) with data about an instance that is following instance n or is intending to follow it, which ordinarily means replication[n].downstream.status = follow.

  • replication[n].downstream.vclock contains the vector clock, which is a table of „id, lsn“ pairs, for example, vclock: {1: 3054773, 4: 8938827, 3: 285902018}. (Notice that the table may have multiple pairs although vclock is a singular name).

    Даже если экземпляр удален, его значения все равно появятся здесь; однако, его значения будут переопределены, если позже экземпляр присоединится с тем же UUID. Пары векторных часов будут появляться только если lsn > 0.

    replication[n].downstream.vclock может быть таким же, как и vclock текущего экземпляра (box.info.vclock), потому что все значения vclock в кластере известны. Мастер будет знать, что находится в копии vclock реплики, потому что, когда мастер делает изменение данных, он посылает информацию об изменении на реплику (включая векторные часы мастера), и реплика отвечает тем, что находится в ее таблице векторных часов.

    A replica also sends its entire vector clock table in response to a master’s heartbeat message, see the heartbeat-message examples in the section Binary protocol – replication.

  • replication[n].downstream.idle – это время (в секундах) с момента последней отправки событий экземпляром n через downstream-репликацию.

  • replication[n].downstream.status – это статус для downstream-репликации:

    • stopped означает, что downstream-репликация остановлена,
    • follow означает, что downstream-репликация находится в процессе (экземпляр n готов принимать данные от мастера или уже делает это).

  • replication[n].downstream.lag is the time difference between the local time at the master node, recorded when a particular transaction was written to the write-ahead log, and the local time recorded when it receives an acknowledgment for this transaction from a replica. Since version 2.10.0. See more in Monitoring a replica set.

  • replication[n].downstream.message and replication[n].downstream.system_message will be nil unless a problem occurs with the connection. For example, if instance n goes down, then one may see status = 'stopped', message = 'unexpected EOF when reading from socket', and system_message = 'Broken pipe'. See also degraded state.

box.info.replication_anon()

box.info.replication_anon()

List all the anonymous replicas following the instance.

Вывод аналогичен выводу box.info.replication, за исключением того, что анонимные реплики индексируются по их uuid, а не по идентификаторам серверов, так как идентификаторы серверов не имеют значения для анонимных реплик.

Обратите внимание, что при вызове box.info.replication_anon, возвращается только количество анонимных реплик текущего экземпляра. Чтобы увидеть полную статистику, нужно вызвать box.info.replication_anon(). Это делается для того, чтобы не перегружать вывод box.info избыточной информацией, так как анонимных реплик может быть много.

Пример:

anonymous_replica:instance001> box.info.replication_anon
---
- count: 1
...

anonymous_replica:instance001> box.info.replication_anon()
---
- 44237cb4-de83-4347-b6db-46274b940acf:
    id: 0
    uuid: 44237cb4-de83-4347-b6db-46274b940acf
    lsn: 0
    downstream:
      status: follow
      idle: 0.81613899999866
      vclock: {1: 7}
      lag: 0
    name: null
...

Нужно отметить, что анонимные реплики скрывают свои lsn от других, поэтому lsn анонимной реплики всегда будет записан как ноль, даже если анонимная реплика выполняет некоторые локальные операции на спейсе. Для того, чтобы узнать lsn конкретной анонимной реплики, необходимо вызвать box.info.lsn на ней.

box.info.ro

box.info.ro

The current mode of the instance (writable or read-only). Learn more in box.info.ro_reason.

Rtype:boolean

Example

sharded_cluster_crud:storage-a-002> box.info.ro
---
- true
...

box.info.ro_reason

box.info.ro_reason

Since: 2.10.0

The reason why the current instance is read-only. To get whether the current instance is writable or read-only, use box.info.ro. If the instance is in writable mode, box.info.ro_reason returns nil.

The possible values returned by ro_reason:

  • election – the instance is not the leader. See box.info.election for details.
  • synchro – the instance is not the owner of the synchronous transaction queue. For details, see box.info.synchro.
  • config – the instance is is configured to be read only.
  • orphan – the instance is in orphan state. For details, see the orphan status page.
Rtype:string

Example

sharded_cluster_crud:storage-a-002> box.info.ro
---
- true
...
sharded_cluster_crud:storage-a-002> box.info.ro_reason
---
- config
...

box.info.schema_version

box.info.schema_version

Since: 2.11.0

The database schema version. A schema version is a number that indicates whether the database schema is changed. For example, the schema_version value grows if a space or index is added or deleted, or a space, index, or field name is changed.

Rtype:number

Example

sharded_cluster_crud:storage-a-002> box.info.schema_version
---
- 87
...

See also: IPROTO_SCHEMA_VERSION

box.info.signature

box.info.signature

The sum of all lsn values from each vector clock (vclock) for all instances in the replica set the current instance belongs to.

Rtype:number

box.info.sql

box.info.sql

Get information about the cache for all SQL prepared statements. The returned table contains the following fields:

  • cache.size – the actual cache size (in bytes) for all SQL prepared statements. To configure the maximum cache size, use the sql.cache_size option.
  • cache.stmt_count – the number of statements in the SQL prepared statement cache.
Rtype:table

box.info.status

box.info.status

The current state of the instance. It can be:

  • running – the instance is loaded
  • loading – the instance is either recovering xlogs/snapshots or bootstrapping
  • orphan – the instance has not (yet) succeeded in joining the required number of masters (see orphan status)
  • hot_standby – the instance is standing by another instance
Rtype:string

box.info.synchro

box.info.synchro

Since version 2.8.1.

The current state of synchronous replication.

In synchronous replication, transaction is considered committed only after achieving the required quorum number. While transactions are collecting confirmations from remote nodes, these transactions are waiting in the queue.

The following information is provided:

  • queue:

    • owner (since version 2.10.0) – ID of the replica that owns the synchronous transaction queue. Once an owner instance appears, all other instances become read-only. If the owner field is 0, then every instance may be writable, but they can’t create any synchronous transactions. To claim or reclaim the queue, use box.ctl.promote() on the instance that you want to promote. To clear the ownership, call box.ctl.demote() on the synchronous queue owner.

      When Raft election is enabled and replication.election_mode is set to candidate, the new Raft leader claims the queue automatically after winning the elections. It means that the value of box.info.synchro.queue.owner becomes equal to box.info.election.leader. When Raft is enabled, no manual intervention with box.ctl.promote() or box.ctl.demote() is required.

    • term (since version 2.10.0) – current queue term. It contains the term of the last PROMOTE request. Usually, it is equal to box.info.election.term. However, the queue term value may be less than the election term. It can happen when a new round of elections has started, but no instance has been promoted yet.

    • len – the number of entries that are currently waiting in the queue.

    • busy (since version 2.10.0) – the boolean value is true when the instance is processing or writing some system request that modifies the queue (for example, PROMOTE, CONFIRM, or ROLLBACK). Until the request is complete, any other incoming synchronous transactions and system requests will be delayed.

    • age (since version 3.2.0) – the time in seconds that the oldest entry currently present in the queue has spent waiting for the quorum to collect.

    • confirm_lag (since version 3.2.0) – the time in seconds that the latest successfully confirmed entry waited for the quorum to collect.

  • quorum – the resulting value of the replication.synchro_quorum configuration option. Since version 2.5.3, the option can be set as a dynamic formula. In this case, the value of the quorum member depends on the current number of replicas.

Example 1:

In this example, the quorum field is equal to 1. That is, synchronous transactions work like asynchronous ones. 1 means that a successful WAL writing to the master is enough to commit.

box_info_synchro:instance001> box.info.synchro
---
- queue:
    owner: 1
    confirm_lag: 0
    term: 2
    age: 0
    len: 0
    busy: false
  quorum: 1
...

Example 2:

Example on GitHub: box_info_synchro

In this example, there are two instances:

  • instance001 is going to be the leader.
  • instance002 is a follower instance.
groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            database:
              mode: rw
            replication:
              synchro_quorum: 2
              synchro_timeout: 1000
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
          instance002:
            database:
              mode: ro
            iproto:
              listen:
              - uri: '127.0.0.1:3302'

On the first instance, grant the user with the super role:

box_info_synchro:instance001> box.schema.user.grant('guest', 'super')

After that, use the box.ctl.promote() function to claim the queue:

box_info_synchro:instance001> box.ctl.promote()

Create a space named sync and enable synchronous replication on this space:

box_info_synchro:instance001> s = box.schema.space.create("sync", {is_sync=true})

Then, create an index:

box_info_synchro:instance001> _ = s:create_index('pk')

Check the current state of synchronous replication:

box_info_synchro:instance001> box.info.synchro
---
- queue:
    owner: 1
    confirm_lag: 0
    term: 2
    age: 0
    len: 0
    busy: false
  quorum: 2
...

On the second instance, simulate failure like if this instance would crash or go out of the network:

box_info_synchro:instance002> os.exit(0)
   ⨯ Connection was closed. Probably instance process isn't running anymore

On the first instance, try to perform some synchronous transactions. The transactions would hang, because the replication.synchro_quorum option is set to 2, and the second instance is not available:

box_info_synchro:instance001> fiber = require('fiber')
---
...
box_info_synchro:instance001> for i = 1, 3 do fiber.new(function() box.space.sync:replace{i} end) end
---
...

Call the box.info.synchro command on the first instance again:

box_info_synchro:instance001> box.info.synchro
---
- queue:
    owner: 1
    confirm_lag: 0
    term: 2
    age: 5.2658250015229
    len: 3
    busy: false
  quorum: 2
...

The len field is now equal to 3. It means that there are 3 transactions waiting in the queue.

box.info.uptime

box.info.uptime

The number of seconds since the instance started. This value can also be retrieved with tarantool.uptime().

Rtype:number

box.info.uuid

box.info.uuid

A globally unique identifier of the current instance. This value corresponds to replication[{n}].uuid. Learn more in box.info.replication.

Rtype:string

box.info.vclock

box.info.vclock

A table with the vclock values of all instances in a replica set which have made data changes.

Rtype:table

box.info.version

box.info.version

The Tarantool version.

See also: tarantool.version, tarantool –version

Rtype:string

box.info.vinyl()

box.info.vinyl()

Get runtime statistics for the vinyl storage engine. This function is deprecated, use box.stat.vinyl() instead.

Submodule box.iproto

Since 2.11.0.

The box.iproto submodule provides the ability to work with the network subsystem of Tarantool. It allows you to extend the IPROTO functionality from Lua. With this submodule, you can:

The submodule exports all IPROTO constants and features to Lua.

IPROTO constants

IPROTO constants in the box.iproto namespace are written in uppercase letters without the IPROTO_ prefix. The constants are divided into several groups:

Each group is located in the corresponding subnamespace without the prefix. For example:

box.iproto.key.SYNC = 0x01
-- ...
box.iproto.type.SELECT = 1
-- ...
box.iproto.flag.COMMIT = 1
-- ...
box.iproto.ballot_key.VCLOCK = 2
-- ...
box.iproto.metadata_key.IS_NULLABLE = 3
-- ...
box.iproto.raft_key.TERM = 0
-- ...

IPROTO features

The submodule exports:

Example

The example converts the feature names from box.iproto.protocol_features set into codes:

-- Features supported by the server
box.iproto.protocol_features = {
    streams = true,
    transactions = true,
    error_extension = true,
    watchers = true,
    pagination = true,
}

-- Convert the feature names into codes
features = {}
for name in pairs(box.iproto.protocol_features) do
    table.insert(features, box.iproto.feature[name])
end
return features -- [0, 1, 2, 3, 4]

Handling the unknown IPROTO request types

Every IPROTO request has a static handler. That is, before version 2.11.0, any unknown request raised an error. Since 2.11.0, a new request type is introduced – IPROTO_UNKNOWN. This type is used to override the handlers of the unknown IPROTO request types. For details, see box.iproto.override() and box_iproto_override functions.

API reference

The table lists all available functions and data of the submodule:

Name Use
box.iproto.key Request keys
box.iproto.type Request types
box.iproto.flag Flags from the IPROTO_FLAGS key
box.iproto.ballot_key Keys from the IPROTO_BALLOT requests
box.iproto.metadata_key Keys nested in the IPROTO_METADATA key
box.iproto.raft Keys from the IPROTO_RAFT_ requests
box.iproto.protocol_version The current IPROTO protocol version
box.iproto.protocol_features The set of supported IPROTO protocol features
box.iproto.feature IPROTO protocol features
box.iproto.override() Set a new IPROTO request handler callback for the given request type
box.iproto.send() Send an IPROTO packet over the session’s socket

box.iproto.key

box.iproto.key

Contains all available request keys, except raft, metadata, and ballot keys. Learn more: Keys used in requests and responses.

Example

tarantool> box.iproto.key.SYNC
---
- 1
...

box.iproto.type

box.iproto.type

Contains all available request types. Learn more about the requests: Client-server requests and responses.

Example

tarantool> box.iproto.type.UNKNOWN
---
- -1
...
tarantool> box.iproto.type.CHUNK
---
- 128
...

box.iproto.flag

box.iproto.flag

Contains the flags from the IPROTO_FLAGS key. Learn more: IPROTO_FLAGS key.

Example

tarantool> box.iproto.flag.COMMIT
---
- 1
...
tarantool> box.iproto.flag.WAIT_SYNC
---
- 2
...

box.iproto.ballot_key

box.iproto.ballot_key

Contains the keys from the IPROTO_BALLOT requests. Learn more: IPROTO_BALLOT keys.

Example

tarantool> box.iproto.ballot_key.IS_RO_CFG
---
- 1
...
tarantool> box.iproto.ballot_key.VCLOCK
---
- 2
...

box.iproto.metadata_key

box.iproto.metadata_key

Contains the IPROTO_FIELD_* keys, which are nested in the IPROTO_METADATA key.

Example

tarantool> box.iproto.metadata_key.NAME
---
- 0
...
tarantool> box.iproto.metadata_key.TYPE
---
- 1
...

box.iproto.raft

box.iproto.raft_key

Contains the keys from the IPROTO_RAFT_* requests. Learn more: Synchronous replication keys.

Example

tarantool> box.iproto.raft_key.TERM
---
- 0
...
tarantool> box.iproto.raft_key.VOTE
---
- 1
...

box.iproto.protocol_version

box.iproto.protocol_version

The current IPROTO protocol version of the server. Learn more: IPROTO_ID.

Example

tarantool> box.iproto.protocol_version
---
- 4
...

box.iproto.protocol_features

box.iproto.protocol_features

The set of IPROTO protocol features supported by the server. Learn more: net.box features, src/box/iproto_features.h, and iproto_features_resolve().

Example

tarantool> box.iproto.protocol_features
---
- transactions: true
  watchers: true
  error_extension: true
  streams: true
  pagination: true
...

box.iproto.feature

box.iproto.feature

Contains the IPROTO protocol features that are supported by the server. Each feature is mapped to its corresponding code. Learn more: IPROTO_FEATURES.

The features in the namespace are written

  • in lowercase letters
  • without the IPROTO_FEATURE_ prefix

Example

tarantool> box.iproto.feature.streams
---
- 0
...
tarantool> box.iproto.feature.transactions
---
- 1
...

box.iproto.override()

box.iproto.override(request_type, handler)

Since version 2.11.0. Set a new IPROTO request handler callback for the given request type.

Параметры:
  • request_type (number) –

    a request type code. Possible values:

    • a type code from box.iproto.type (except box.iproto.type.UNKNOWN) – override the existing request type handler.
    • box.iproto.type.UNKNOWN – override the handler of unknown request types.
  • handler (function) –

    IPROTO request handler. The signature of a handler function: function(sid, header, body), where

    Returns true on success, otherwise false. On false, there is a fallback to the default handler. Also, you can indicate an error by throwing an exception. In this case, the return value is false, but this does not always mean a failure.

    To reset the request handler, set the handler parameter to nil.
Return:

none

Possible errors:

If a Lua handler throws an exception, the behavior is similar to that of a remote procedure call. The following errors are returned to the client over IPROTO (see src/lua/utils.h):

  • ER_PROC_LUA – an exception is thrown from a Lua handler, diagnostic is not set.
  • diagnostics from src/box/errcode.h – an exception is thrown, diagnostic is set.

For details, see src/box/errcode.h.

Предупреждение

When using box.iproto.override(), it is important that you follow the wire protocol. That is, the server response should match the return value types of the corresponding request type. Otherwise, it could lead to peer breakdown or undefined behavior.

Example:

Define a handler function for the box.iproto.type.SELECT request type:

local function iproto_select_handler_lua(header, body)
    if body.space_id == 512 then
        box.iproto.send(box.session.id(),
                { request_type = box.iproto.type.OK,
                  sync = header.SYNC,
                  schema_version = box.info.schema_version },
                { data = { 1, 2, 3 } })
        return true
    end
    return false
end

Override box.iproto.type.SELECT handler:

box.iproto.override(box.iproto.type.SELECT, iproto_select_handler_lua)

Reset box.iproto.type.SELECT handler:

box.iproto.override(box.iproto.type.SELECT, nil)

Override a handler function for the unknown request type:

box.iproto.override(box.iproto.type.UNKNOWN, iproto_unknown_request_handler_lua)

box.iproto.send()

box.iproto.send(sid, header[, body])

Since version 2.11.0. Send an IPROTO packet over the session’s socket with the given MsgPack header and body. The header and body contain exported IPROTO constants from the box.iproto() submodule. Possible IPROTO constant formats:

  • a lowercase constant without the IPROTO_ prefix (schema_version, request_type)
  • a constant from the corresponding box.iproto subnamespace (box.iproto.SCHEMA_VERSION, box.iproto.REQUEST_TYPE)

The function works for binary sessions only. For details, see box.session.type().

Параметры:
  • sid (number) – the IPROTO session identifier (see box.session.id())
  • header (table|string) – a request header encoded as MsgPack
  • body (table|string|nil) – a request body encoded as MsgPack
Return:

0 on success, otherwise an error is raised
Rtype:

number

Possible errors:

  • ER_SESSION_CLOSED – the session is closed.
  • ER_NO_SUCH_SESSION – the session does not exist.
  • ER_MEMORY_ISSUE – out-of-memory limit has been reached.
  • ER_WRONG_SESSION_TYPE – the session type is not binary.

For details, see src/box/errcode.h.

Examples:

Send a packet using Lua tables and string IPROTO constants as keys:

box.iproto.send(box.session.id(),
        { request_type = box.iproto.type.OK,
          sync = 10,
          schema_version = box.info.schema_version },
        { data = 1 })

Send a packet using Lua tables and numeric IPROTO constants:

box.iproto.send(box.session.id(),
        { [box.iproto.key.REQUEST_TYPE] = box.iproto.type.OK,
          [box.iproto.key.SYNC] = 10,
          [box.iproto.key.SCHEMA_VERSION] = box.info.schema_version },
        { [box.iproto.key.DATA] = 1 })

Send a packet that contains only the header:

box.iproto.send(box.session.id(),
        { request_type = box.iproto.type.OK,
          sync = 10,
          schema_version = box.info.schema_version })

Submodule box.read_view

The box.read_view submodule contains functions related to read views.

Name Use
box.read_view.list() Return an array of all active database read views.
box.read_view.open() Create a new read view.

box.read_view.list()

read_view.list()

Return an array of all active database read views. This array might include the following read view types:

  • read views created by application code (Enterprise Edition only)
  • system read views (used, for example, to make a checkpoint or join a new replica)

Read views created by application code also have the space field. The field lists all spaces available in a read view, and may be used like a read view object returned by box.read_view.open().

Примечание

read_view.list() also contains read views created using the C API (box_raw_read_view_new()). Note that you cannot access database spaces included in such views from Lua.

Example:

tarantool> box.read_view.list()
---
- - timestamp: 1138.98706933
    signature: 47
    is_system: false
    status: open
    vclock: &0 {1: 47}
    name: read_view1
    id: 1
  - timestamp: 1172.202995842
    signature: 49
    is_system: false
    status: open
    vclock: &1 {1: 49}
    name: read_view2
    id: 2
...

box.read_view.open()

Enterprise Edition

This API is available in the Enterprise Edition only.

box.read_view:open({opts})

Create a new read view.

Параметры:
  • opts (table) – (optional) configurations options for a read view. For example, the name option specifies a read view name. If name is not specified, a read view name is set to unknown.
Return:

a created read view object
Rtype:

read_view_object

Example:

tarantool> read_view1 = box.read_view.open({name = 'read_view1'})
object read_view_object

An object that represents a read view.

read_view_object:info()

Get information about a read view such as a name, status, or ID. All the available fields are listed below in the object options.

Return:information about a read view
Rtype:table
read_view_object:close()

Close a read view. After the read view is closed, its status is set to closed. On an attempt to use it, an error is raised.

read_view_object.status

A read view status. The possible values are open and closed.

Rtype:string
read_view_object.id

A unique numeric identifier of a read view.

Rtype:number
read_view_object.name

A read view name. You can specify a read view name in the box.read_view.open() arguments.

Rtype:string
read_view_object.is_system

Determine whether a read view is system. For example, system read views can be created to make a checkpoint or join a new replica.

Rtype:boolean
read_view_object.timestamp

The fiber.clock() value at the moment of opening a read view.

Rtype:number
read_view_object.vclock

The box.info.vclock value at the moment of opening a read view.

Rtype:table
read_view_object.signature

The box.info.signature value at the moment of opening a read view.

Rtype:number
read_view_object.space

Get access to database spaces included in a read view. You can use this field to query space data.

Rtype:space object

Вложенный модуль box.schema

Вложенный модуль box.schema содержит функции для определения данных для спейсов, пользователей, ролей, кортежей и последовательностей.

Ниже приведен перечень всех функций модуля box.schema.

Имя Использование
box.schema.space.create() Создание спейса
box.schema.upgrade() Обновить базу данных
box.schema.downgrade() Downgrade a database
box.schema.downgrade_issues() List downgrade issues for the specified Tarantool version
box.schema.downgrade_versions() List Tarantool versions available for downgrade
box.schema.user.create() Создание пользователя
box.schema.user.drop() Удаление пользователя
box.schema.user.exists() Проверка существования пользователя
box.schema.user.grant() Выдача прав пользователю или роли
box.schema.user.revoke() Отмена прав пользователя или роли
box.schema.user.password() Получение хеша пароля пользователя
box.schema.user.passwd() Ассоциация пароля с пользователем
box.schema.user.info() Получение описания прав пользователя
box.schema.role.create() Создание роли
box.schema.role.drop() Удаление роли
box.schema.role.exists() Проверка наличия роли
box.schema.role.grant() Выдача прав роли
box.schema.role.revoke() Отмена прав роли
box.schema.role.info() Получение описания прав роли
box.schema.func.create() Создание кортежа с функцией
box.schema.func.drop() Удаление кортежа с функцией
box.schema.func.exists() Проверка наличия кортежа с функцией
box.schema.func.reload() Перезагрузка модуля на C (со всеми его функциями) без перезапуска сервера

box.schema.space.create()

box.schema.space.create(space-name[, {space_opts}])
box.schema.create_space(space-name[, {space_opts}])

Create a space. You can use either syntax. For example, s = box.schema.space.create('tester') has the same effect as s = box.schema.create_space('tester').

There are three syntax variations for object references targeting space objects, for example box.schema.space.drop(space-id) drops a space. However, the common approach is to use functions attached to the space objects, for example space_object:drop().

Следующим шагом после создания спейса будет создание индекса для него, после чего можно будет выполнять вставку, выборку и другие функции box.space.

Параметры:
возвращает:

объект спейса
тип возвращаемого значения:
 

пользовательские данные

space_opts

object space_opts

Space options that include the space id, format, field count, constraints and foreign keys, and so on. These options are passed to the box.schema.space.create() method.

Примечание

These options are also passed to space_object:alter().

space_opts.if_not_exists

Create a space only if a space with the same name does not exist already. Otherwise, do nothing but do not cause an error.

Type: boolean
Default: false
space_opts.engine

A storage engine.

Type: string
Default: memtx
Possible values: memtx, vinyl
space_opts.id

A unique numeric identifier of the space: users can refer to spaces with this id instead of the name.

Type: number
Default: last space’s ID + 1
space_opts.field_count

A fixed count of fields. For example, if field_count=5, it is illegal to insert a tuple with fewer than or more than 5 fields.

Type: number
Default: 0 (not fixed)
space_opts.user

The name of the user who is considered to be the space’s owner for authorization purposes.

Type: string
Default: current user’s name
space_opts.format

Field names and types. See the illustrations of format clauses in the space_object:format() description and in the box.space._space example. Optional and usually not specified.

Type: table
Default: blank
space_opts.is_local

Space contents are replication-local: changes are stored in the write-ahead log of the local node but there is no replication.

Type: boolean
Default: false
space_opts.temporary

Space contents are temporary: changes are not stored in the write-ahead log and there is no replication.

Примечание

Vinyl does not support temporary spaces.

Type: boolean
Default: false
space_opts.is_sync

Any transaction doing a DML request on this space becomes synchronous.

Пример:

box.schema.space.create('bands', { is_sync = true })
Type: boolean
Default: false
space_opts.constraint

The constraints that space tuples must satisfy.

Type: table
Default: blank

Пример:

-- Define a tuple constraint function --
box.schema.func.create('check_person', {
    language = 'LUA',
    is_deterministic = true,
    body = 'function(t, c) return (t.age >= 0 and #(t.name) > 3) end'
})

-- Create a space with a tuple constraint --
customers = box.schema.space.create('customers', {constraint = 'check_person'})
space_opts.foreign_key

The foreign keys for space fields.

Type: table
Default: blank

Пример:

-- Create a space with a tuple foreign key --
box.schema.space.create("orders", {
    foreign_key = {
        space = 'customers',
        field = {customer_id = 'id', customer_name = 'name'}
    }
})

box.space.orders:format({
    {name = "id", type = "number"},
    {name = "customer_id" },
    {name = "customer_name"},
    {name = "price_total", type = "number"},
})

Если выполнить box.cfg{read_only=true...} во время конфигурации по-разному влияет на спейсы в зависимости от опций, использованных во время box.schema.space.create, как описано в таблице:

Характеристика Можно создать? Допускает запись? Реплицируется? Сохраняется?
(по умолчанию) нет нет да да
temporary (временный) нет да нет нет
is_local нет да нет да

Пример:

tarantool> s = box.schema.space.create('space55')
---
...
tarantool> s = box.schema.space.create('space55', {
         >   id = 555,
         >   temporary = false
         > })
---
- error: Space 'space55' already exists
...
tarantool> s = box.schema.space.create('space55', {
         >   if_not_exists = true
         > })
---
...

box.schema.upgrade()

box.schema.upgrade()

If you created a database with an older Tarantool version and have now installed a newer version, make the request box.schema.upgrade(). This updates Tarantool system spaces to match the currently installed version of Tarantool. You can learn about the general upgrade process from the Upgrades topic.

For example, here is what happens when you run box.schema.upgrade() with a database created with Tarantool version 1.6.4 to version 1.7.2 (only a small part of the output is shown):

tarantool> box.schema.upgrade()
alter index primary on _space set options to {"unique":true}, parts to [[0,"unsigned"]]
alter space _schema set options to {}
create view _vindex...
grant read access to 'public' role for _vindex view
set schema version to 1.7.0
---
...

You can also put the request box.schema.upgrade() inside a box.once() function in your Tarantool initialization file. On startup, this will create new system spaces, update data type names (for example, num -> unsigned, str -> string) and options in Tarantool system spaces.

See also: box.schema.downgrade()

box.schema.downgrade()

box.schema.downgrade(version)

Allows you to downgrade a database to the specified Tarantool version. This might be useful if you need to run a database on older Tarantool versions.

To prepare a database for using it on an older Tarantool instance, call box.schema.downgrade and pass the desired Tarantool version:

tarantool> box.schema.downgrade('2.8.4')

Примечание

The Tarantool’s downgrade procedure is similar to the upgrade process that is described in the Upgrades topic. You need to run box.schema.downgrade() only on master and execute box.snapshot() on every instance in a replica set before restart to an older version.

To see Tarantool versions available for downgrade, call box.schema.downgrade_versions(). The oldest release available for downgrade is 2.8.2.

Note that the downgrade process might fail if the database enables specific features not supported in the target Tarantool version. You can see all such issues using the box.schema.downgrade_issues() method, which accepts the target version. For example, downgrade to the 2.8.4 version fails if you use tuple compression or field constraints in your database:

tarantool> box.schema.downgrade_issues('2.8.4')
---
- - Tuple compression is found in space 'bands', field 'band_name'. It is supported
    starting from version 2.10.0.
  - Field constraint is found in space 'bands', field 'year'. It is supported starting
    from version 2.10.0.
...

See also: box.schema.upgrade()

box.schema.downgrade_versions()

box.schema.downgrade_versions()

Return a list of Tarantool versions available for downgrade. To learn how to downgrade a database to the specified Tarantool version, see box.schema.downgrade().

Return:a list of Tarantool versions
Rtype:table

box.schema.downgrade_issues()

box.schema.downgrade_issues(version)

Return a list of downgrade issues for the specified Tarantool version. To learn how to downgrade a database to the specified Tarantool version, see box.schema.downgrade().

Return:a list of downgrade issues
Rtype:table

box.schema.user.create()

box.schema.user.create(name[, {options}])

Создание пользователя. Чтобы получить информацию о том, как происходит управление данными пользователя в Tarantool, см. раздел Пользователи и справочник по спейсу _user.

Возможные параметры:

  • if_not_exists (если отсутствует) = true|false (правда/ложь, по умолчанию ложь) - логическое значение boolean; true (правда) означает, что ошибка не выпадет, если пользователь уже существует,
  • password (default = „“) - string; the password = password specification is good because in a URI (Uniform Resource Identifier) it is usually illegal to include a username without a password.

Примечание

Максимальное количество пользователей – 32.

Параметры:
возвращает:

nil

Примеры:

box.schema.user.create('testuser', { password = 'foobar' })

See also: Managing users.

box.schema.user.drop()

box.schema.user.drop(username[, {options}])

Удаление пользователя. Чтобы получить информацию о том, как происходит управление данными пользователя в Tarantool, см. раздел Пользователи и справочник по спейсу _user.

Параметры:
  • username (string) – имя пользователя
  • options (table) – if_exists (если существует) = true|false (правда/ложь, по умолчанию ложь) - логическое значение boolean; true (правда) означает, что ошибка не выпадет, если такой пользователь не существует.

Примеры:

box.schema.user.drop('testuser')

See also: Managing users.

box.schema.user.exists()

box.schema.user.exists(username)

Выдача true (правда), если пользователь существует; выдача false (ложь), если пользователь отсутствует. Чтобы получить информацию о том, как происходит управление данными пользователя в Tarantool, см. раздел Пользователи и справочник по спейсу _user.

Параметры:
  • username (string) – имя пользователя
тип возвращаемого значения:
 

логическое значение bool

See also: Getting a user’s information.

box.schema.user.grant()

box.schema.user.grant(username, permissions, object-type, object-name[, {options}])
box.schema.user.grant(username, permissions, 'universe'[, nil, {options}])
box.schema.user.grant(username, role-name[, nil, nil, {options}])

Выдача прав пользователю или другой роли.

Параметры:
  • username (string) – the name of a user to grant privileges to
  • permissions (string) – one or more permissions to grant to the user (for example, read or read,write)
  • object-type (string) – a database object type to grant permissions to (for example, space, role, or function)
  • object-name (string) – the name of a database object to grant permissions to
  • role-name (string) – the name of a role to grant to the user
  • options (table) – grantor, if_not_exists

Если указана 'function','object-name', то должен существовать кортеж _func с этим именем объекта.

Variation: instead of object-type, object-name say universe which means „all object-types and all objects“. In this case, object name is omitted.

Variation: instead of permissions, object-type, object-name say role-name (see section Roles).

Variation: instead of box.schema.user.grant('username','usage,session','universe',nil, {if_not_exists=true}) say box.schema.user.enable('username').

Возможны следующие опции:

  • grantor = grantor_name_or_id – строка или число, для пользователя, который выдает права,
  • if_not_exists = true|false (default = false) - boolean; true означает, что ошибки не должно быть, если пользователь уже имеет права.

Пример:

box.schema.user.grant('testuser', 'read', 'space', 'writers')
box.schema.user.grant('testuser', 'read,write', 'space', 'books')

See also: Managing users.

box.schema.user.revoke()

box.schema.user.revoke(username, permissions, object-type, object-name[, {options}])
box.schema.user.revoke(username, permissions, 'universe'[, nil, {options}])
box.schema.user.revoke(username, role-name[, nil, nil, {options}])

Отмена прав пользователя или другой роли.

Параметры:
  • username (string) – the name of the user
  • permissions (string) – one or more permissions to revoke from the user (for example, read or read,write)
  • object-type (string) – a database object type to revoke permissions from (for example, space, role, or function)
  • object-name (string) – the name of a database object to revoke permissions from
  • options (table) – if_exists

Должен существовать пользователь, должен существовать объект, но если задано {if_exists=true}, то ошибки не будет, если у пользователя нет прав.

Вариант: вместо тип-объекта, имя-объекта введите „universe“, что означает „все типы объектов и все объекты“.

Variation: instead of permissions, object-type, object-name say role-name (see section Roles).

Variation: instead of box.schema.user.revoke('username','usage,session','universe',nil, {if_exists=true}) say box.schema.user.disable('username').

Пример:

box.schema.user.revoke('testuser', 'write', 'space', 'books')

See also: Managing users.

box.schema.user.password()

box.schema.user.password(password)

Выдача хеша пароля пользователя. Чтобы получить информацию о том, как происходит управление паролями в Tarantool, см. раздел Пароли и справочник по спейсу _user.

Примечание

  • Если у пользователя, который не является пользователем „guest“ нет пароля, невозможно подключиться к Tarantool через этого пользователя. Пользователь считается только “внутренним”, его нельзя использовать для удаленного подключения. Такие пользователи могут работать, если они определили какие-либо процедуры с помощью SETUID, на которые есть доступ у пользователей с внешним подключением. Таким образом, внешние пользователи могут не создавать/удалять объекты, а только вызывать процедуры.
  • Для пользователя „guest“ невозможно установить пароль: это бы привело к путанице, поскольку „guest“ является пользователем по умолчанию для любого установленного подключения по бинарному порту, а Tarantool не требует пароль при установке бинарного подключения. Тем не менее, можно сменить текущего пользователя на пользователя ‘guest’, предоставив AUTH-пакет (пакет авторизации) без пароля или с пустым паролем. Данная функция полезна для пулов соединений, которые хотят повторно использовать соединение для другого пользователя без повторного подключения.
Параметры:
  • password (string) – пароль для хеширования
тип возвращаемого значения:
 

string

Пример:

box.schema.user.password('foobar')

box.schema.user.passwd()

box.schema.user.passwd([username, ]password)

Sets a password for a currently logged in or a specified user:

  • A currently logged-in user can change their password using box.schema.user.passwd(password).
  • An administrator can change the password of another user with box.schema.user.passwd(username, password).
Параметры:
  • username (string) – a username
  • password (string) – a new password

Пример:

box.schema.user.passwd('testuser', 'foobar')

See also: Managing users.

box.schema.user.info()

box.schema.user.info([username])

Выдача описания прав пользователя.

Параметры:
  • username (string) – имя пользователя. Необязательный параметр; если не указать, информация будет для авторизованного пользователя.

See also: Getting a user’s information.

box.schema.role.create()

box.schema.role.create(role-name[, {options}])

Создание роли. Чтобы получить информацию о том, как происходит управление данными о ролях в Tarantool, см. раздел Роли.

Параметры:
  • role-name (string) – имя роли, которое должно соответствовать правилам именования объектов
  • options (table) – if_not_exists (если отсутствует) = true|false (правда/ложь, по умолчанию ложь) - логическое значение boolean; true (правда) означает, что ошибка не выпадет, если роль уже существует.
возвращает:

nil

Пример:

box.schema.role.create('books_space_manager')
box.schema.role.create('writers_space_reader')

See also: Managing roles.

box.schema.role.drop()

box.schema.role.drop(role-name[, {options}])

Удаление роли. Чтобы получить информацию о том, как происходит управление данными о ролях в Tarantool, см. раздел Роли.

Параметры:
  • role-name (string) – название роли
  • options (table) – if_exists (если существует) = true|false (правда/ложь, по умолчанию ложь) - логическое значение boolean; true (правда) означает, что ошибка не выпадет, если такая роль не существует.

Пример:

box.schema.role.drop('writers_space_reader')

See also: Managing roles.

box.schema.role.exists()

box.schema.role.exists(role-name)

Выдача true (правда), если роль существует; выдача false (ложь), если роль отсутствует.

Параметры:
  • role-name (string) – название роли
тип возвращаемого значения:
 

логическое значение bool

See also: Getting a role’s information.

box.schema.role.grant()

box.schema.role.grant(role-name, permissions, object-type, object-name[, option])
box.schema.role.grant(role-name, permissions, 'universe'[, nil, option])
box.schema.role.grant(role-name, role-name[, nil, nil, option])

Выдача прав роли.

Параметры:
  • role-name (string) – the name of the role
  • permissions (string) – one or more permissions to grant to the role (for example, read or read,write)
  • object-type (string) – a database object type to grant permissions to (for example, space, role, or function)
  • object-name (string) – the name of a database object to grant permissions to
  • option (table) – if_not_exists = true|false (default = false) - boolean; true means there should be no error if the role already has the privilege

Должна существовать роль, должен существовать объект.

Variation: instead of object-type, object-name say universe which means „all object-types and all objects“. In this case, object name is omitted.

Variation: instead of permissions, object-type, object-name say role-name – to grant a role to a role.

Пример:

box.schema.role.grant('books_space_manager', 'read,write', 'space', 'books')

See also: Managing roles.

box.schema.role.revoke()

box.schema.role.revoke(role-name, permissions, object-type, object-name)

Отмена прав роли.

Параметры:
  • role-name (string) – the name of the role
  • permissions (string) – one or more permissions to revoke from the role (for example, read or read,write)
  • object-type (string) – a database object type to revoke permissions from (for example, space, role, or function)
  • object-name (string) – the name of a database object to revoke permissions from

Должна существовать роль, должен существовать объект, но ошибка не выпадет, если у роли нет прав.

Variation: instead of object-type, object-name say universe which means „all object-types and all objects“.

Variation: instead of permissions, object-type, object-name say role-name.

See also: Managing roles.

box.schema.role.info()

box.schema.role.info(role-name)

Выдача описания прав роли.

Параметры:
  • role-name (string) – название роли.

See also: Getting a role’s information.

box.schema.func.create()

box.schema.func.create(func_name[, function_options])

Create a function. The created function can be used in different usage scenarios, for example, in field or tuple constraints or functional indexes.

Using the body option, you can make a function persistent. In this case, the function is «persistent» because its definition is stored in a snapshot (the box.space._func system space) and can be recovered if the server restarts.

Параметры:
возвращает:

nil

Примечание

box.schema.user.grant() can be used to allow the specified user or role to execute the created function.

Example 1: a non-persistent Lua function

The example below shows how to create a non-persistent Lua function:

box.schema.func.create('calculate')
box.schema.func.create('calculate', {if_not_exists = false})
box.schema.func.create('calculate', {setuid = false})
box.schema.func.create('calculate', {language = 'LUA'})

Example 2: a persistent Lua function

The example below shows how to create a persistent Lua function, show its definition using box.func.{func-name}, and call this function using box.func.{func-name}:call([parameters]):

tarantool> lua_code = [[function(a, b) return a + b end]]
tarantool> box.schema.func.create('sum', {body = lua_code})

tarantool> box.func.sum
---
- is_sandboxed: false
  is_deterministic: false
  id: 2
  setuid: false
  body: function(a, b) return a + b end
  name: sum
  language: LUA
...

tarantool> box.func.sum:call({1, 2})
---
- 3
...

To call functions using net.box, use net_box:call().

Example 3: a persistent SQL expression used in a tuple constraint

The code snippet below defines a function that checks a tuple’s data using the SQL expression:

box.schema.func.create('check_person', {
    language = 'SQL_EXPR',
    is_deterministic = true,
    body = [["age" > 21 AND "name" != 'Admin']]
})

Then, this function is used to create a tuple constraint:

local customers = box.schema.space.create('customers', { constraint = 'check_person' })
customers:format({
    { name = 'id', type = 'number' },
    { name = 'name', type = 'string' },
    { name = 'age', type = 'number' },
})
customers:create_index('primary', { parts = { 1 } })

On an attempt to insert a tuple that doesn’t meet the required criteria, an error is raised:

customers:insert { 2, "Bob", 18 }
-- error: Check constraint 'check_person' failed for a tuple

function_options

object function_options

A table containing options passed to the box.schema.func.create(func-name [, function_options]) function.

function_options.if_not_exists

Specify whether there should be no error if the function already exists.

Type: boolean
Default: false
function_options.setuid

Make Tarantool treat the function’s caller as the function’s creator, with full privileges. Note that setuid works only over binary ports. setuid doesn’t work if you invoke a function using the admin console or inside a Lua script.

Type: boolean
Default: false
function_options.language

Specify the function language. The possible values are:

  • LUA: define a Lua function in the body attribute.

  • SQL_EXPR: define an SQL expression in the body attribute. An SQL expression can only be used as a field or tuple constraint.

  • C: import a C function using its name from a .so file. Learn how to call C code from Lua in the C tutorial.

    Примечание

    To reload a C module with all its functions without restarting the server, call box.schema.func.reload().

Type: string
Default: LUA
function_options.is_sandboxed

Whether the function should be executed in an isolated environment. This means that any operation that accesses the world outside the sandbox is forbidden or has no effect. Therefore, a sandboxed function can only use modules and functions that cannot affect isolation:

assert, assert, error, ipairs, math.*, next, pairs, pcall, print, select, string.*, table.*, tonumber, tostring, type, unpack, xpcall, utf8.*.

Also, a sandboxed function cannot refer to global variables – they are treated as local variables because the sandbox is established with setfenv. So, a sandboxed function is stateless and deterministic.

Type: boolean
Default: false
function_options.is_deterministic

Specify whether a function should be deterministic.

Type: boolean
Default: false
function_options.is_multikey

If true is set in the function definition for a functional index, the function returns multiple keys. For details, see the example.

Type: boolean
Default: false
function_options.body

Specify a function body. You can set a function’s language using the language attribute.

The code snippet below defines a constraint function that checks a tuple’s data using a Lua function:

box.schema.func.create('check_person', {
    language = 'LUA',
    is_deterministic = true,
    body = 'function(t, c) return (t.age >= 0 and #(t.name) > 3) end'
})

In the following example, an SQL expression is used to check a tuple’s data:

box.schema.func.create('check_person', {
    language = 'SQL_EXPR',
    is_deterministic = true,
    body = [["age" > 21 AND "name" != 'Admin']]
})

Example: A persistent SQL expression used in a tuple constraint

Type: string
Default: nil
function_options.takes_raw_args

Since: 2.10.0

If set to true for a Lua function and the function is called via net.box (conn:call()) or by box.func.<func-name>:call(), the function arguments are passed being wrapped in a MsgPack object:

local msgpack = require('msgpack')
box.schema.func.create('my_func', {takes_raw_args = true})
local my_func = function(mp)
    assert(msgpack.is_object(mp))
    local args = mp:decode() -- array of arguments
end

If a function forwards most of its arguments to another Tarantool instance or writes them to a database, the usage of this option can improve performance because it skips the MsgPack data decoding in Lua.

Type: boolean
Default: false
function_options.exports

Specify the languages that can call the function.

Example: exports = {'LUA', 'SQL'}

See also: Calling Lua routines from SQL

Type: table
Default: {'LUA'}
function_options.param_list

Specify the Lua type names for each parameter of the function.

Example: param_list = {'number', 'number'}

See also: Calling Lua routines from SQL

Type: table
function_options.returns

Specify the Lua type name for a function’s return value.

Example: returns = 'number'

See also: Calling Lua routines from SQL

Type: string

box.schema.func.drop()

box.schema.func.drop(func-name[, {options}])

Удаление кортежа с функцией. Чтобы получить информацию о том, как происходит управление данными функций в Tarantool, см. справочник по спейсу _func.

Параметры:
  • func-name (string) – имя функции
  • options (table) – if_exists (если существует) = true|false (правда/ложь, по умолчанию ложь) - логическое значение boolean; true (правда) означает, что ошибка не выпадет, если кортеж в _func не существует.

Пример:

box.schema.func.drop('calculate')

box.schema.func.exists()

box.schema.func.exists(func-name)

Выдача true (правда), если кортеж с функцией существует; выдача false (ложь), если кортеж с функцией отсутствует.

Параметры:
  • func-name (string) – имя функции
тип возвращаемого значения:
 

логическое значение bool

Пример:

box.schema.func.exists('calculate')

box.schema.func.reload()

box.schema.func.reload([name])

Перезагрузка модуля на C (со всеми его функциями) без перезапуска сервера.

С точки зрения внутреннего устройства, Tarantool загружает новую копию модуля (библиотека общего пользования *.so) и запускает маршрутизацию всех новых запросов на новую версию. Предыдущая версия остается активной до тех пор, пока не завершатся все начатые вызовы. Все библиотеки общего пользования загружены с RTLD_LOCAL (см. «man 3 dlopen»), таким образом, множество копий могут работать одновременно без каких-либо проблем.

Примечание

Перезагрузка не сработает, если модуль был загружен из Lua-скрипта с ffi.load().

Параметры:
  • name (string) – имя модуля для перезагрузки

Пример:

-- перегрузить целиком всё содержимое модуля
box.schema.func.reload('module')

Последовательности

Вводная информация о последовательностях дается в разделе Последовательности главы «Модель данных». Здесь же приведена подробная информация о каждой функции и каждом параметре.

Все функции, связанные с последовательностями, требуют наличия соответствующих прав.

Ниже приведен перечень всех функций модуля box.schema.sequence.

Имя Использование
box.schema.sequence.create() Создание нового генератора последовательностей
sequence_object:next() Генерация и выдача следующего значения
sequence_object:alter() Изменение параметров последовательности
sequence_object:reset() Возврат последовательности в оригинальное состояние
sequence_object:set() Установка нового значения
sequence_object:current() Возврат последнего найденного значения
sequence_object:drop() Удаление последовательности
использование последовательностей в create_index() Создание индекса с опцией последовательности

Пример:

Ниже представлен пример, иллюстрирующий все параметры и операции для последовательностей:

s = box.schema.sequence.create(
               'S2',
               {start=100,
               min=100,
               max=200,
               cache=100000,
               cycle=false,
               step=100
               })
s:alter({step=6})
s:next()
s:reset()
s:set(150)
s:drop()

box.schema.sequence.create()

box.schema.sequence.create(name[, options])

Создание нового генератора последовательностей.

Параметры:
  • name (string) – имя последовательности
  • options (table) – см. краткий обзор в таблице «Параметры для box.schema.sequence.create()» (в разделе Последовательности главы «Модель данных»), а более подробную информацию ниже.
возвращает:

ссылка на новый объект последовательности.

Параметры:

  • start – НАЧАЛЬНОЕ значение. Тип = целое число, по умолчанию = 1.

  • min – МИНИМАЛЬНОЕ значение. Тип = целое число, по умолчанию = 1.

  • max –МАКСИМАЛЬНОЕ значение. Тип = целое число, по умолчанию = 9223372036854775807.

    Есть следующее правило: min <= start <= max. Например, нельзя указать {start=0}, поскольку указанное начальное значение (0) будет меньше, чем минимальное значение, используемое по умолчанию (1).

    Есть следующее правило: min <= следующее-значение <= max. Например, если сгенерированное значение будет 1000, но максимальное значение – 999, это будет считаться переполнением.

    There is a rule: start and min and max must all be <= 9223372036854775807 which is 2^63 - 1 (not 2^64).

  • cycle – значение ЦИКЛА. Тип = bool (логический), по умолчанию = false (ложь).

    Если следующее значение в генераторе последовательности будет переполнением, это вызовет ошибку – не считая случаев, когда задан цикл (cycle == true).

    Если же cycle == true, отсчет начинается заново с МИНИМАЛЬНОГО значения или с МАКСИМАЛЬНОГО значения (не с НАЧАЛЬНОГО значения).

  • cache – значение КЭША. Тип = беззнаковое целое число, по умолчанию = 0.

    В данный момент Tarantool игнорирует это значение, оно зарезервировано для последующего использования.

  • step – значение УВЕЛИЧЕНИЯ. Тип = целое число, по умолчанию = 1.

    Это значение прибавляется к предыдущему.

sequence_object:next()

object sequence_object
sequence_object:next()

Генерация и выдача следующего значения.

Простой алгоритм для генерации:

  • В первый раз вернуть НАЧАЛЬНОЕ значение.
  • Если предыдущее значение плюс значение УВЕЛИЧЕНИЯ меньше, чем МИНИМАЛЬНОЕ значение, или больше, чем МАКСИМАЛЬНОЕ значение, будет переполнение, поэтому либо выдать сообщение об ошибке (если цикл не задан – cycle = false) или вернуть МАКСИМАЛЬНОЕ значение (если цикл задан – cycle = true – и step < 0), или вернуть МИНИМАЛЬНОЕ значение (если цикл задан – cycle = true – и step > 0).

Если ошибки нет, сохранить результат, который становится «предыдущим значением».

Например, предположим, что для последовательности „S“:

  • min == -6,
  • max == -1,
  • step == -3,
  • start = -2,
  • cycle = true,
  • предыдущее значение = -2.

Тогда box.sequence.S:next() вернет -5, потому что -2 + (-3) == -5.

Затем box.sequence.S:next() снова вернет -1, потому что -5 + (-3) < -6, что будет переполнением, которое вызовет цикл, а max == -1.

Для данной функции необходимы права на запись („write“) на последовательность.

Примечание

Данную функцию не следует использовать в транзакциях между движками (транзакции, в которых используется и движок memtx, и движок vinyl).

Чтобы увидеть предыдущее значение, не изменяя его, сделайте выборку из системного спейса _sequence_data.

sequence_object:alter()

object sequence_object
sequence_object:alter(options)

Функцию alter() можно использовать для изменения любых параметров последовательности. Требования и ограничения в данном случае такие же, как для box.schema.sequence.create().

Параметры:

  • start – НАЧАЛЬНОЕ значение. Тип = целое число, по умолчанию = 1.

  • min – МИНИМАЛЬНОЕ значение. Тип = целое число, по умолчанию = 1.

  • max –МАКСИМАЛЬНОЕ значение. Тип = целое число, по умолчанию = 9223372036854775807.

    Есть следующее правило: min <= start <= max. Например, нельзя указать {start=0}, поскольку указанное начальное значение (0) будет меньше, чем минимальное значение, используемое по умолчанию (1).

    Есть следующее правило: min <= следующее-значение <= max. Например, если сгенерированное значение будет 1000, но максимальное значение – 999, это будет считаться переполнением.

  • cycle – значение ЦИКЛА. Тип = bool (логический), по умолчанию = false (ложь).

    Если следующее значение в генераторе последовательности будет переполнением, это вызовет ошибку – не считая случаев, когда задан цикл (cycle == true).

    Если же cycle == true, отсчет начинается заново с МИНИМАЛЬНОГО значения или с МАКСИМАЛЬНОГО значения (не с НАЧАЛЬНОГО значения).

  • cache – значение КЭША. Тип = беззнаковое целое число, по умолчанию = 0.

    В данный момент Tarantool игнорирует это значение, оно зарезервировано для последующего использования.

  • step – значение УВЕЛИЧЕНИЯ. Тип = целое число, по умолчанию = 1.

    Это значение прибавляется к предыдущему.

sequence_object:reset()

object sequence_object
sequence_object:reset()

Возврат последовательности в оригинальное состояние. Смысл в том, что последующий вызов next() вернет начальное значение start. Для данной функции необходимы права на запись („write“) на последовательность.

sequence_object:set()

object sequence_object
sequence_object:set(new-previous-value)

Установка «предыдущего значения» на new-previous-value (новое предыдущее значение). Для данной функции необходимы права на запись („write“) на последовательность.

sequence_object:current()

object sequence_object
sequence_object:current()

Since version 2.4.1. Return the last retrieved value of the specified sequence or throw an error if no value has been generated yet (next() has not been called yet, or current() is called right after reset() is called).

Пример:

tarantool> sq = box.schema.sequence.create('test')
---
...
tarantool> sq:current()
---
- error: Sequence 'test' is not started
...
tarantool> sq:next()
---
- 1
...
tarantool> sq:current()
---
- 1
...
tarantool> sq:set(42)
---
...
tarantool> sq:current()
---
- 42
...
tarantool> sq:reset()
---
...
tarantool> sq:current()  -- error
---
- error: Sequence 'test' is not started
...

sequence_object:drop()

object sequence_object
sequence_object:drop()

Удаление существующей последовательности.

использование последовательностей в create_index()

object space_object
space_object:create_index(... [sequence='...' option] ...)

Можно использовать опцию sequence=имя-последовательности (или sequence=id-последовательности, или sequence=true) при создании или изменении первичного индекса. Происходит ассоциация последовательности с индексом, так что следующий вызов insert() поместит следующее сгенерированное число в поле первичного ключа, если в противном случае поле было бы nil.

The syntax may be any of:
sequence = sequence identifier
or sequence = {id = sequence identifier }
or sequence = {field = field number }
or sequence = {id = sequence identifier , field = field number }
or sequence = true
or sequence = {}.
The sequence identifier may be either a number (the sequence id) or a string (the sequence name). The field number may be the ordinal number of any field in the index; default = 1. Examples of all possibilities: sequence = 1 or sequence = 'sequence_name' or sequence = {id = 1} or sequence = {id = 'sequence_name'} or sequence = {id = 1, field = 1} or sequence = {id = 'sequence_name', field = 1} or sequence = {field = 1} or sequence = true or sequence = {}. Notice that the sequence identifier can be omitted, if it is omitted then a new sequence is created automatically with default name = space-name_seq. Notice that the field number does not have to be 1, that is, the sequence can be associated with any field in the primary-key index.

Например, если „Q“ – это последовательность, а „T“ – это новый спейс, то сработает:

tarantool> box.space.T:create_index('Q',{sequence='Q'})
---
- unique: true
  parts:
  - type: unsigned
    is_nullable: false
    fieldno: 1
  sequence_id: 8
  id: 0
  space_id: 514
  name: Q
  type: TREE
...

(Обратите внимание, что теперь в индексе есть поле идентификатора последовательности sequence_id.)

И сработает:

tarantool> box.space.T:insert{box.NULL,0}
---
- [1, 0]
...

Примечание

The index key type may be either „integer“ or „unsigned“. If any of the sequence options is a negative number, then the index key type should be „integer“.

Users should not insert a value greater than 9223372036854775807, which is 2^63 - 1, in the indexed field. The sequence generator will ignore it.

Последовательность нельзя удалить, если она связана с индексом. Тем не менее, можно использовать index_object:alter(), чтобы показать, что последовательность не связана с индексом, например так box.space.T.index.I:alter({sequence=false}).

If a sequence was created automatically because the sequence identifier was omitted, then it will be dropped automatically if the index is altered so that sequence=false, or if the index is dropped.

index_object:alter() can also be used to associate a sequence with an existing index, with the same syntax for options.

When a sequence is used with an index based on a JSON path, inserted tuples must have all components of the path preceding the autoincrement field, and the autoincrement field. To achieve that use box.NULL rather than nil. Example:

s = box.schema.space.create('test')
s:create_index('pk', {parts = {{'[1].a.b[1]', 'unsigned'}}, sequence = true})
s:replace{} -- error
s:replace{{c = {}}} -- error
s:replace{{a = {c = {}}}} -- error
s:replace{{a = {b = {}}}} -- error
s:replace{{a = {b = {nil}}}} -- error
s:replace{{a = {b = {box.NULL}}}} -- ok

Вложенный модуль box.session

Вложенный модуль box.session позволяет делать запросы состояния сессии, вносить записи во временную Lua-таблицу по отдельной сессии, отправлять экстренные сообщения и настраивать триггеры, которые сработают в начале или окончании сессии.

Сессия – это объект, связанный с каждым подключением клиента.

Ниже приведен перечень всех функций и элементов модуля box.session.

Имя Использование
box.session.id() Получение идентификатора текущей сессии
box.session.exists() Проверка наличия сессии
box.session.peer() Получение адреса хоста и порта подключенного узла
box.session.sync() Получение целочисленной константы sync
box.session.user() Получение имени текущего пользователя
box.session.type() Получение типа соединения или повода к действию
box.session.su() Изменение текущего пользователя
box.session.uid() Получение идентификатора текущего пользователя
box.session.euid() Получение идентификатора текущего действующего пользователя
box.session.storage Таблица с именами и значениями по сессии
box.session.on_connect() Определение триггера для подключения
box.session.on_disconnect() Определение триггера для отключения
box.session.on_auth() Определение триггера для аутентификации
box.session.on_access_denied() Определение триггера для регистрации запрещенных действий
box.session.push() Отправка внеполосного сообщения

box.session.id()

box.session.id()

Return the unique identifier (ID) for the current session.

возвращает:the session identifier; 0 or -1 if there is no session
тип возвращаемого значения:
 число

box.session.exists()

box.session.exists(id)
возвращает:1, если сессия есть; 0, если сессии нет.
тип возвращаемого значения:
 boolean (логический)

box.session.peer()

box.session.peer(id)

Данная функция сработает только в том случае, если есть подключенная программа, то есть если было выполнено подключение к отдельному экземпляру Tarantool.

возвращает:Адрес хоста и порт подключенного узла, например «127.0.0.1:55457». Если существует сессия, но отсутствует подключение к отдельному экземпляру, вернется null. Команда выполняется на экземпляре сервера, поэтому «локальное имя» – это хост и порт экземпляра сервера, а «имя узла» – это хост и порт клиента.
тип возвращаемого значения:
 string (строка)

Возможные ошибки: „session.peer(): сессия отсутствует“

box.session.sync()

box.session.sync()
возвращает:значение целочисленной константы sync, используемой в бинарном протоколе. Это значение будет недействительным после отключения сессии.
тип возвращаемого значения:
 число

This function is local for the request, i.e. not global for the session. If the connection behind the session is multiplexed, this function can be safely used inside the request processor.

box.session.user()

box.session.user()
возвращает:имя текущего пользователя
тип возвращаемого значения:
 строка

box.session.type()

box.session.type()
возвращает:тип соединения или повод к действию.
тип возвращаемого значения:
 string

Возможные возвращаемые значения:

  • „binary“ (бинарное), если подключение было выполнено по бинарному протоколу, например, к объекту с помощью box.cfg{listen=…};
  • „console“ (консоль), если подключение было выполнено по административной консоли, например, к объекту с помощью console.listen;
  • „repl“ (репликация), если подключение было выполнено напрямую, например, при использовании Tarantool в качестве клиента;
  • „applier“ (наложение), если действие происходит по причине репликации, независимо от типа подключения;
  • „background“ (в фоне), если действие происходит в фоновом файбере, независимо от того, был ли Tarantool запущен в фоновом режиме.

box.session.type() используется для триггера при замене on_replace() на реплике – значение будет „applier“ только в том случае, если триггер был активирован по причине запроса, выполненного на мастере.

box.session.su()

box.session.su(user-name[, function-to-execute])

Изменение текущего пользователя Tarantool – аналогично Unix-команде su.

Или, если указана выполняемая функция (function-to-execute), временное изменение текущего пользователя Tarantool во время выполнения функции – аналогично Unix-команде sudo.

Параметры:
  • user-name (string) – целевое имя пользователя
  • function-to-execute – имя функции или определение функции. Дополнительные параметры могут передаваться в box.session.su, они будут интерпретироваться как параметры выполняемой функции.

Пример:

tarantool> function f(a) return box.session.user() .. a end
---
...

tarantool> box.session.su('guest', f, '-xxx')
---
- guest-xxx
...

tarantool> box.session.su('guest',function(...) return ... end,1,2)
---
- 1
- 2
...

box.session.uid()

box.session.uid()
возвращает:ID текущего пользователя.
тип возвращаемого значения:
 число

У каждого пользователя есть уникальное имя (узнать с помощью box.session.user()) и уникальный идентификатор (узнать с помощью box.session.uid()). Значения хранятся вместе в спейсе _user.

box.session.euid()

box.session.euid()
возвращает:рабочий ID текущего пользователя.

Аналогично box.session.uid(), за исключением двух случаев:

  • Первый случай: если вызов box.session.euid() выполняется в рамках функции, вызываемой по box.session.su(user-name, function-to-execute) – в таком случае box.session.euid() вернет измененный идентификатор пользователя (пользователь, который указан в параметре user-name функции su), но box.session.uid() вернет идентификатор оригинального пользователя (пользователя, который вызывает функцию su).
  • Второй случай: если вызов box.session.euid() выполняется в рамках функции по box.schema.func.create(function-name, {setuid= true}), и используется бинарный протокол – в таком случае box.session.euid() вернет идентификатор пользователя, который создал функцию «function-name», а box.session.uid() вернет идентификатор пользователя, который вызывает эту функцию «function-name».
тип возвращаемого значения:
 число

Пример:

tarantool> box.session.su('admin')
---
...
tarantool> box.session.uid(), box.session.euid()
---
- 1
- 1
...
tarantool> function f() return {box.session.uid(),box.session.euid()} end
---
...
tarantool> box.session.su('guest', f)
---
- - 1
  - 0
...

box.session.storage

box.session.storage

Lua-таблица с произвольными неупорядоченными именами и значениями по сессии, которая хранится до конца сессии. Например, эту таблицу можно использовать для хранения текущих задач при работе с очередями сообщений в Tarantool.

Пример:

tarantool> box.session.peer(box.session.id())
---
- 127.0.0.1:45129
...
tarantool> box.session.storage.random_memorandum = "Don't forget the eggs"
---
...
tarantool> box.session.storage.radius_of_mars = 3396
---
...
tarantool> m = ''
---
...
tarantool> for k, v in pairs(box.session.storage) do
         >   m = m .. k .. '='.. v .. ' '
         > end
---
...
tarantool> m
---
- 'radius_of_mars=3396 random_memorandum=Don't forget the eggs. '
...

box.session.on_connect()

box.session.on_connect([trigger-function[, old-trigger-function]])

Определение исполняемого триггера во время создания новой сессии при подключении по консоли console.connect. Функция с триггером будет первой исполняемой функцией после создания сессии. Если триггер не выполняется и выдает ошибку, эта ошибка отправляется на клиент, и подключение разрывается.

Параметры:
  • trigger-function (function) – функция, в которой будет триггер
  • old-trigger-function (function) – существующая функция с триггером, которую заменит новая
возвращает:

nil или указатель функции

Если указаны параметры (nil, old-trigger-function), старый триггер будет удален.

Если не указан ни один параметр, ответом будет список существующих функций с триггером.

Подробная информация о характеристиках триггера находится в разделе Триггеры.

Пример:

tarantool> function f ()
         >   x = x + 1
         > end
tarantool> box.session.on_connect(f)

Предупреждение

Если триггер всегда приводит к ошибке, подключение к серверу для его переустановки может стать невозможным.

box.session.on_disconnect()

box.session.on_disconnect([trigger-function[, old-trigger-function]])

Определение исполняемого триггера после отключения клиента. Если функция с триггером вызывает ошибку, то ошибка записывается в журнал, в противном случае записей не будет. Триггер вызывается во время сессии клиента и может получить доступ к свойствам сессии, как box.session.id().

Начиная с версии 1.10, функция с триггером вызывается сразу же после прерывания сессии, даже если сделанные запросы не были выполнены.

Параметры:
  • trigger-function (function) – функция, в которой будет триггер
  • old-trigger-function (function) – существующая функция с триггером, которую заменит новая
возвращает:

nil или указатель функции

Если указаны параметры (nil, old-trigger-function), старый триггер будет удален.

Если не указан ни один параметр, ответом будет список существующих функций с триггером.

Подробная информация о характеристиках триггера находится в разделе Триггеры.

Пример №1

tarantool> function f ()
         >   x = x + 1
         > end
tarantool> box.session.on_disconnect(f)

Пример №2

После следующей серии запросов экземпляр Tarantool запишет сообщение с помощью модуля log при подключении или отключении любого пользователя.

function log_connect ()
  local log = require('log')
  local m = 'Connection. user=' .. box.session.user() .. ' id=' .. box.session.id()
  log.info(m)
end

function log_disconnect ()
  local log = require('log')
  local m = 'Disconnection. user=' .. box.session.user() .. ' id=' .. box.session.id()
  log.info(m)
end

box.session.on_connect(log_connect)
box.session.on_disconnect(log_disconnect)

Вот что может быть записано в файл журнала при обычной установке:

2014-12-15 13:21:34.444 [11360] main/103/iproto I>
    Connection. user=guest id=3
2014-12-15 13:22:19.289 [11360] main/103/iproto I>
    Disconnection. user=guest id=3

box.session.on_auth()

box.session.on_auth([trigger-function[, old-trigger-function]])

Определение триггера, используемого во время аутентификации.

Вызов функции on_auth с триггером происходит в следующих обстоятельствах:

  1. Функция console.connect включает в себя проверку аутентификации всех пользователей, кроме „guest“. Вызов функции on_auth с триггером происходит после триггера on_connect только в том случае, если подключение было успешным.
  2. В бинарном протоколе есть отдельный пакет для аутентификации. В этом случае подключение и аутентификация считаются отдельными действиям.

В отличие от других типов триггеров, вызов функций с триггером on_auth происходит до события. Таким образом, функция с таким триггером, как function auth_function () v = box.session.user(); end, определит v как «guest», то есть имя пользователя до проведения аутентификации. Чтобы получить имя пользователя после проведения аутентификации, используйте специальный синтаксис: function auth_function (user_name) v = user_name; end

Если триггер не выполняется и выдает ошибку, эта ошибка отправляется на клиент, и подключение разрывается.

Параметры:
  • trigger-function (function) – функция, в которой будет триггер
  • old-trigger-function (function) – существующая функция с триггером, которую заменит новая
возвращает:

nil или указатель функции

Если указаны параметры (nil, old-trigger-function), старый триггер будет удален.

Если не указан ни один параметр, ответом будет список существующих функций с триггером.

Подробная информация о характеристиках триггера находится в разделе Триггеры.

Пример 1

tarantool> function f ()
         >   x = x + 1
         > end
tarantool> box.session.on_auth(f)

Пример 2

Более сложный пример с двумя экземплярами сервера.

Первый экземпляр сервера настроен на прослушивание по порту 3301; имя пользователя по умолчанию – „admin“. Есть три триггера on_auth:

  • В первом триггере есть функция без аргументов, которая только смотрит на box.session.user().
  • Во втором триггере есть функция с аргументом user_name, которая может смотреть на box.session.user() и user_name.
  • В третьем триггере есть функция с аргументом user_name и аргументом status, которая может смотреть на box.session.user() и user_name, и``status``.

Второй экземпляр сервера подключится по console.connect, а затем отобразит переменные, определенные функциями с триггером.

-- На первом экземпляре сервера, прослушивание на котором настроено на порт 3301
box.cfg{listen=3301}
function function1()
  print('function 1, box.session.user()='..box.session.user())
  end
function function2(user_name)
  print('function 2, box.session.user()='..box.session.user())
  print('function 2, user_name='..user_name)
  end
function function3(user_name, status)
  print('function 3, box.session.user()='..box.session.user())
  print('function 3, user_name='..user_name)
  if status == true then
    print('function 3, status = true, authorization succeeded')
    end
  end
box.session.on_auth(function1)
box.session.on_auth(function2)
box.session.on_auth(function3)
box.schema.user.passwd('admin')

-- На втором экземпляре сервера, который подключается по порту 3301
console = require('console')
console.connect('admin:admin@localhost:3301')

Теперь результат выглядит следующим образом:

function 3, box.session.user()=guest
function 3, user_name=admin
function 3, status = true, authorization succeeded
function 2, box.session.user()=guest
function 2, user_name=admin
function 1, box.session.user()=guest

box.session.on_access_denied()

box.session.on_access_denied([trigger-function[, old-trigger-function]])

Определение триггера для ответа на попытки пользователя выполнить неразрешенные ему действия.

Параметры:
  • trigger-function (function) – функция, в которой будет триггер
  • old-trigger-function (function) – существующая функция с триггером, которую заменит новая
возвращает:

nil или указатель функции

Если указаны параметры (nil, old-trigger-function), старый триггер будет удален.

Если не указан ни один параметр, ответом будет список существующих функций с триггером.

Подробная информация о характеристиках триггера находится в разделе Триггеры.

Пример:

Например, администратор сервера может регистрировать запрещенные действия:

tarantool> function on_access_denied(op, type, name)
         > log.warn('User %s tried to %s %s %s without required privileges', box.session.user(), op, type, name)
         > end
---
...
tarantool> box.session.on_access_denied(on_access_denied)
---
- 'function: 0x011b41af38'
...
tarantool> function test() print('you shall not pass') end
---
...
tarantool> box.schema.func.create('test')
---
...

И когда какой-нибудь пользователь без соответствующих прав попытается вызвать test()` и получит ошибку, сервер выполнит этот триггер и запишет в журнал «User *имя_пользователя* tried to Execute function test without required privileges» (Пользователь имя_пользователя пытался выполнить функцию текст без соответствующих прав).

box.session.push()

box.session.push(message[, sync])

Создание внеполосного сообщения. Под внеполосным мы понимаем дополнительное сообщение, которое дополняет то, что отправляется в сети по обычным каналам. Хотя box.session.push() можно вызвать в любое время, на практике эта функция используется в сетях, настроенных с помощью модуля net.box, и вызывается сервером (на «удаленной системе с базой данных», если использовать нашу терминологию для net.box), а у клиента есть возможность принимать такие сообщения.

Функция возвращает ошибку, если сессия была прервана.

Параметры:
  • message (any-Lua-type) – что отправляется
  • sync (int) – необязательный аргумент, указывающий на сессию. Этот аргумент берётся из предшествующего вызова box.session.sync(). Если аргумент опущен, применяется значение по умолчанию — текущее значение box.session.sync(). Аргумент признан устаревшим в версии Tarantool 2.4.2, а начиная с версии 2.5.1 его использование приводит к ошибке.
тип возвращаемого значения:
 

{nil, ошибка} или true:

  • Если результатом будет ошибка, то вернется nil вместе с объектом ошибки.
  • Если результатом будет не ошибка, то вернется логическое значение true (правда).
  • When the return is true, the message has gone to the network buffer as a packet with a different header code so the client can distinguish from an ordinary Okay response.

Единственная задача сервера – вызвать box.session.push(), поскольку нет автоматического механизма, который показал бы, что сообщение получено.

Задача клиента заключается в том, чтобы проверять наличие таких сообщений после отправки чего-либо на сервер. Основные клиентские методы – conn:call, conn:eval, conn:select, conn:insert, conn:replace, conn:update, conn:upsert, delete – могут привести к отправке такого сообщения сервером.

Ситуация 1: когда клиент делает синхронный вызов со значением параметра {async=false} по умолчанию. Есть два необязательных дополнительных параметра: on_push=function-name и on_push_ctx=function-argument. Когда клиент получает внеполосное сообщение в сессии, он вызывает «имя-функции(аргумент-функции)». Например, с такими значениями параметров: {on_push=table.insert, on_push_ctx=messages} – клиент произведет вставку полученных данных в таблицу под названием „messages“.

Ситуация 2: когда клиент делает асинхронный вызов с измененным значением параметра {async=true}. Здесь не разрешены on_push и on_push_ctx, но сообщения можно увидеть путем вызова pairs() в цикле.

Осложненная ситуация 2: pairs() зависит от времени ожидания. Таким образом, есть необязательный аргумент – время ожидания для итерации. Если время ожидания истечет до получения нового сообщения или окончательного ответа, вернется ошибка. Чтобы проверить наличие ошибки, можно использовать первый параметр в цикле (если цикл начинается с «for i, message in future:pairs()», то первым параметром в цикле будет i). Если это будет box.NULL, то второй параметр (в нашем примере «message») – это объект ошибки.

Пример:

-- Создайте две оболочки. В оболочке №1 настройте сервер, а
-- в нем функцию, которая содержит box.session.push:
box.cfg{listen=3301}
box.schema.user.grant('guest','read,write,execute','universe')
x = 0
fiber = require('fiber')
function server_function() x=x+1; fiber.sleep(1); box.session.push(x); end

-- В оболочке №2 подключитесь к серверу в качестве клиента, который
-- поддерживает Lua (как второй Tarantool-сервер, работающий
-- в качестве клиента), и создайте таблицу, в которую мы будем получать сообщения:
net_box = require('net.box')
conn = net_box.connect(3301)
messages_from_server = {}

-- В оболочке №2 удаленно вызовите функцию и получите
-- СИНХРОННОЕ внеполосное сообщение:
conn:call('server_function', {},
          {is_async = false,
           on_push = table.insert,
           on_push_ctx = messages_from_server})
messages_from_server
-- Через секунду, во время которой происходит запрос fiber.sleep()
-- в server_function, результат в таблице
--  messages_from_server будет следующим: 1. Проверим:
-- tarantool> messages_from_server
-- ---
-- - - 1
-- ...
-- Хорошо. Это означает, что box.session.push(x) сработала,
-- поскольку мы знаем, что x был 1.

-- В оболочке №2 удаленно вызовите ту же самую функцию
-- для получения АСИНХРОННОГО внеполосного сообщения. При этом мы не можем
-- использовать параметры on_push и on_push_ctx, но можем использовать pairs():
future = conn:call('server_function', {}, {is_async = true})
messages = {}
keys = {}
for i, message in future:pairs() do
    table.insert(messages, message) table.insert(keys, i) end
messages
future:wait_result(1000)
for i, message in future:pairs() do
    table.insert(messages, message) table.insert(keys, i) end
messages
-- Задержки нет, поскольку conn:call не ждет
-- окончания вызова функции server_function. После первой итерации
-- цикла pairs(), видим, что таблица пуста. Это выглядит так:
-- tarantool> messages
-- ---
-- - - 2
--   - []
-- ...
-- Это нормально, поскольку сервер еще не вызвал
-- box.session.push(). При второй итерации
-- цикла pairs(), видим значение x во время
-- второго вызова box.session.push(). Так:
-- tarantool> messages
-- ---
-- - - 2
--   - &0 []
--   - 2
--   - *0
-- ...
-- Хорошо. Это означает, что сообщение было асинхронным, и
-- box.session.push() выполнила свою задачу.

Вложенный модуль box.slab

Вложенный модуль box.slab предоставляет доступ к статистике распределения slab. Механизм распределения slab представляет собой основной тип распределения для хранения кортежей. Такое распределение можно использовать для отслеживания использования памяти и фрагментации памяти.

Ниже приведен перечень всех функций модуля box.slab.

Имя Использование
box.runtime.info() Отображение отчета по использованию памяти во время исполнения Lua-кода
box.slab.info() Отображение обобщенного отчета по использованию памяти для распределения slab
box.slab.stats() Отображение подробного отчета по использованию памяти для распределения slab

box.runtime.info()

box.runtime.info()

Отображение отчета по использованию runtime-памяти в байтах.

Runtime-память включает в себя внутреннюю память Lua и runtime-арену. В памяти Lua хранятся объекты Lua. На runtime-арене хранятся объекты, специфичные для Tarantool: временные пользовательские кортежи, сетевые буферы и прочие объекты, связанные с подсистемой сервера приложений.

возвращает:
  • lua – размер динамической памяти Lua, контролируемой сборщиком мусора в Lua;
  • maxalloc – максимальный размер runtime-памяти;
  • used – объем памяти, используемый runtime-памятью в данный момент.
тип возвращаемого значения:
 

таблица

Пример:

tarantool> box.runtime.info()
---
- lua: 913710
  maxalloc: 4398046510080
  used: 12582912
...
tarantool> box.runtime.info().used
---
- used: 12582912
...

box.slab.info()

box.slab.info()

Show an aggregated memory usage report in bytes for the slab allocator. This report is useful for assessing out-of-memory risks.

box.slab.info выдает несколько показателей:

  • items_used_ratio
  • arena_used_ratio
  • quota_used_ratio

При мониторинге используемой памяти в memtx’е есть два возможных сценария:

1 сценарий: 0.5 < items_used_ratio < 0.9

../../../../_images/items_used_ratio1.svg

Очевидно, память сильно фрагментирована. Проверьте, сколько у вас классов slab, подсчитав количество различных классов с помощью box.slab.stats(). Если классов slab много (больше нескольких десятков), то память может закончиться, даже если её занято не так много. На каждом slab может быть использовано мало элементов. Но всякий раз при выделении кортежа, размер которого отличается от любого существующего класса, Tarantool может понадобиться новый slab из области распределения slab. И если осталось мало пустых slab, то произойдет попытка увеличения квоты, что, в свою очередь, может привести к ошибке нехватки памяти из-за низкой оставшейся квоты памяти.

2 сценарий: items_used_ratio > 0.9

../../../../_images/items_used_ratio2.svg

Память заканчивается. Высокие показатели использования памяти. Память не фрагментирована, но каждый уровень механизма распределения slab почти пуст. Следует подумать об увеличении лимита памяти Tarantool (box.cfg.memtx_memory).

Вывод: основной показатель нехватки памяти – quota_used_ratio. Тем не менее, существует множество абсолютно стабильных установок с высоким показателем quota_used_ratio , поэтому необходимо обращать на это внимание, когда два других показателя также высоки (arena и item used).

возвращает:
  • quota_size – лимит памяти для механизма распределения slab (как настроено в параметре memtx_memory, по умолчанию 2^28 байтов = 268 435 456 байтов)
  • quota_used – использовано механизмом распределения slab
  • items_size – выделено только для кортежей
  • items_used – использовано только для кортежей
  • arena_size – выделено для кортежей и индексов вместе
  • arena_used – использовано для кортежей и индексов вместе
  • items_used_ratio = items_used / items_size
  • quota_used_ratio = quota_used / quota_size
  • arena_used_ratio = arena_used / arena_size
тип возвращаемого значения:
 

таблица

Пример:

tarantool> box.slab.info()
---
- items_size: 228128
  items_used_ratio: 1.8%
  quota_size: 1073741824
  quota_used_ratio: 0.8%
  arena_used_ratio: 43.2%
  items_used: 4208
  quota_used: 8388608
  arena_size: 2325176
  arena_used: 1003632
...

tarantool> box.slab.info().arena_used
---
- 1003632
...

box.slab.stats()

box.slab.stats()

Отображение подробного отчета об использовании памяти (в байтах) для распределения slab. Отчет разбивается на группы по размеру элементов данных, а также по размеру slab’а (64 байта, 136 байтов и т.д.). Отчет включает в себя информацию о памяти, выделенной на хранение и кортежей, и индексов.

возвращает:
  • mem_free – это выделенная, но не используемая в данный момент память;
  • mem_used – это память, используемая для хранения элементов данных (кортежей и индексов);
  • item_count – это количество хранимых элементов;
  • item_size – это размер каждого элемента данных;
  • slab_count – это количество выделенных slab’ов;
  • slab_size – это размер каждого выделенного slab’а.
тип возвращаемого значения:
 

таблица

Пример:

Ниже представлен пример отчета для первой группы:

tarantool> box.slab.stats()[1]
---
- mem_free: 16232
  mem_used: 48
  item_count: 2
  item_size: 24
  slab_count: 1
  slab_size: 16384
...

В отчете показано, что есть два элемента данных (item_count = 2), которые хранятся в одном (slab_count = 1) 24-байтовом slab’е (item_size = 24), поэтому объем используемой памяти mem_used = 2 * 24 = 48 байтов. Кроме того, размер slab’а slab_size составляет 16384 байта, из которых 16384 - 48 = 16232 байта свободны (mem_free).

В полном отчете будет статистика по использованию памяти во всех группах:

tarantool> box.slab.stats()
---
- - mem_free: 16232
    mem_used: 48
    item_count: 2
    item_size: 24
    slab_count: 1
    slab_size: 16384
  - mem_free: 15720
    mem_used: 560
    item_count: 14
    item_size: 40
    slab_count: 1
    slab_size: 16384
  <...>
  - mem_free: 32472
    mem_used: 192
    item_count: 1
    item_size: 192
    slab_count: 1
    slab_size: 32768
  - mem_free: 1097624
    mem_used: 999424
    item_count: 61
    item_size: 16384
    slab_count: 1
    slab_size: 2097152
  ...

The total mem_used for all groups in this report equals arena_used in box.slab.info() report.

Вложенный модуль box.space

CRUD operations in Tarantool are implemented by the box.space submodule. It has the data-manipulation functions select, insert, replace, update, upsert, delete, get, put. It also has members, such as id, and whether or not a space is enabled.

Ниже приведен перечень всех функций и элементов модуля box.space.

Имя Использование
box.schema.space.create() Создание спейса
space_object:alter() Изменение спейса
space_object:auto_increment() Генерация ключа + вставка кортежа
space_object:bsize() Подсчет байтов
space_object:count() Подсчет кортежей
space_object:create_index() Создание индекса
space_object:delete() Удаление кортежа
space_object:drop() Удаление спейса
space_object:format() Объявление имен и типов полей
space_object:frommap() Конвертация ассоциативного массива в кортеж или таблицу
space_object:get() Выбор кортежа
space_object:insert() Вставка кортежа
space_object:len() Подсчет кортежей
space_object:on_replace() Создание триггера замены с функцией, которая не может изменять кортеж
space_object:before_replace() Создание триггера замены с функцией, которая может изменять кортеж
space_object:pairs() Подготовка к итерации
space_object:put() Вставка или замена кортежа
space_object:rename() Переименование спейса
space_object:replace() / put() Вставка или замена кортежа
space_object:run_triggers() Включение/отключение триггера замены
space_object:select() Выбор одного или более кортежей
space_object:stat() Get statistics on memory usage
space_object:truncate() Удаление всех кортежей
space_object:update() Обновление кортежа
Upgrading space schema Upgrade the space format and tuples
space_object:upsert() Обновление кортежа
space_object extensions Любая функция / метод, которые хочет добавить любой пользователь
box.space.create_check_constraint() Создание проверочного ограничения
space_object:enabled Флаг, если спейс активен – true
space_object:field_count Необходимое количество полей
space_object.id Числовой идентификатор спейса
space_object.index Контейнер для индексов спейса
box.space._cluster (Метаданные) Список наборов реплик
box.space._func (Метаданные) Список кортежей с функциями
box.space._index (Метаданные) Список индексов
box.space._vindex (Метаданные) Список индексов, доступных текущему пользователю
box.space._priv (Метаданные) Список прав
box.space._vpriv (Метаданные) Список прав, доступных текущему пользователю
box.space._schema (Метаданные) Список схем
box.space._sequence (Метаданные) Список последовательностей
box.space._sequence_data (Метаданные) Список последовательностей
box.space._space (Метаданные) Список спейсов
box.space._vspace (Метаданные) Список спейсов, доступных текущему пользователю
box.space._space_sequence (Metadata) List of connections between spaces and sequences
box.space._vspace_sequence (Metadata) List of connections between spaces and sequences accessible for the current user
box.space._user (Метаданные) Список пользователей
box.space._vuser (Метаданные) Список пользователей, доступных текущему пользователю
box.space._ck_constraint (Метаданные) Список проверочных ограничений
box.space._collation (Метаданные) Список видов сортировки
box.space._vcollation (Метаданные) Список видов сортировки, доступных текущему пользователю
Представления системных спейсов (Метаданные) Спейсы, имена которых начинаются с _v
box.space._session_settings (Метаданные) Список настроек, которые влияют на поведение текущего сеанса

См. также практические примеры работы с CRUD-операциями.

space_object:alter()

object space_object
space_object:alter(options)

Для версии 2.5.2 и выше. Изменение существующего спейса. Этот метод меняет определенные параметры спейса.

Параметры:
  • options (table) – the space options such as field_count, user, format, name, and other. The full list of these options with descriptions parameters is provided in box.schema.space.create()
возвращается:

ничего в случае успеха; ошибка при неудаче

Пример:

tarantool> s = box.schema.create_space('tester')
---
...
tarantool> format = {{name = 'field1', type = 'unsigned'}}
---
...
tarantool> s:alter({name = 'tester1', format = format})
---
...
tarantool> s.name
---
- tester1
...
tarantool> s:format()
---
- [{'name': 'field1', 'type': 'unsigned'}]
...

space_object:auto_increment()

object space_object
space_object:auto_increment(tuple)

Вставка нового кортежа, используя первичный ключ с автоматическим увеличением. В спейсе, указанном через space_object должен быть первичный TREE-индекс типа „unsigned“ или „integer“, или „number“. Поле первичного ключа будет увеличиваться перед вставкой.

Данный метод объявлен устаревшим с версии 1.7.5 – лучше использовать последовательности.

Параметры:
возвращает:

вставленный кортеж.
тип возвращаемого значения:
 

кортеж

Факторы сложности Размер индекса, тип индекса, количество индексов, к которым получен доступ, настройки журнала упреждающей записи (WAL).

Возможные ошибки:

  • неподходящий тип индекса;
  • проиндексированное поле первичного ключа не является числовым.

Пример:

tarantool> box.space.tester:auto_increment{'Fld#1', 'Fld#2'}
---
- [1, 'Fld#1', 'Fld#2']
...
tarantool> box.space.tester:auto_increment{'Fld#3'}
---
- [2, 'Fld#3']
...

space_object:bsize()

object space_object
space_object:bsize()
Параметры:
возвращает:

Количество байтов в спейсе. Это число, которое хранится во внутренней памяти Tarantool, представляет собой общее количество байтов во всех кортежах, не включая ключи индекса. Для получения информации об измерении размера индекса, см. index_object:bsize().

Пример:

tarantool> box.space.tester:bsize()
---
- 22
...

space_object:count()

object space_object
space_object:count([key][, iterator])

Возврат количества кортежей. Если сравнивать с len(), то count() работает медленнее, поскольку сканирует весь спейс для подсчета кортежей.

Параметры:
  • space_object (space_object) – ссылка на объект
  • key (scalar/table) – значения поля первичного ключа, которые должны возвращаться в виде Lua-таблицы, если ключ составной
  • iterator – метод сопоставления
возвращает:

Количество кортежей.

Возможные ошибки:

Пример:

tarantool> box.space.tester:count(2, {iterator='GE'})
---
- 1
...

space_object:delete()

object space_object
space_object:delete(key)

Delete a tuple identified by the primary key.

Параметры:
  • space_object (space_object) – ссылка на объект
  • key (scalar/table) – значения поля первичного ключа, которые должны возвращаться в виде Lua-таблицы, если ключ составной
возвращает:

удаленный кортеж.
тип возвращаемого значения:
 

tuple

Возможные ошибки:

Факторы сложности: Размер индекса, тип индекса

Note regarding storage engine: vinyl will return nil, rather than the deleted tuple.

Пример:

tarantool> box.space.tester:delete(1)
---
- [1, 'My first tuple']
...
tarantool> box.space.tester:delete(1)
---
...
tarantool> box.space.tester:delete('a')
---
- error: 'Supplied key type of part 0 does not match index part type:
  expected unsigned'
...

Для получения дополнительной информации о сценариях использования и типичных ошибках, см. Пример: использование операций с данными далее в разделе.

space_object:drop()

object space_object
space_object:drop()

Удаление спейса. Метод реализуется в фоновом режиме и не блокирует последующие запросы.

Параметры:
возвращает:

nil

Возможные ошибки: space_object не существует.

Факторы сложности Размер индекса, тип индекса, количество индексов, к которым получен доступ, настройки журнала упреждающей записи (WAL).

Пример:

box.space.space_that_does_not_exist:drop()

space_object:format()

object space_object
space_object:format([format-clause])

Объявление имен и типов полей.

Параметры:
возвращает:

nil, если не указан оператор формата

Возможные ошибки:

  • space_object does not exist
  • field names are duplicated
  • type is not legal

Примечание

Если вам нужно выполнить миграцию схемы, обратитесь к разделу Миграции.

Как правило, Tarantool допускает поля без имен и без указания типа. Но с помощью format можно, например, задокументировать, что N-ное поле представляет собой поле для фамилии и должно содержать строковое значение. Также оператор формата можно указать в box.schema.space.create().

Оператор формата для каждого поля содержит определение в фигурных скобках: {name='...',type='...'[,is_nullable=...]}, где:

  • The name value may be any string, provided that two fields do not have the same name.
  • The type value may be any of allowed types: any | unsigned | string | integer | number | varbinary | boolean | double | decimal | uuid | array | map | scalar, but for creating an index use only indexed fields;
  • (Optional) The is_nullable boolean value specifies whether nil can be used as a field value. See also: key_part.is_nullable.
  • (Optional) The collation string value specifies the collation used to compare field values. See also: key_part.collation.
  • (Optional) The constraint table specifies the constraints that the field value must satisfy.
  • (Optional) The foreign_key table specifies the foreign keys for the field.
  • (Optional) The default value specifies the explicit default value for the field or the argument of the default function if default_func is specified.
  • (Optional) The default_func string value specifies the name of the field’s default function. To pass the default function’s argument, add the default parameter.

В кортежах недопустимы значения неправильного типа. Пример ниже вызовет ошибку:

--Этот пример вызовет ошибку.
box.space.tester:format({{' ',type='number'}})
box.space.tester:insert{'string-which-is-not-a-number'}

В кортежах недопустимы нулевые значения, если is_nullable=false, что задано по умолчанию. Пример ниже вызовет ошибку:

--Этот пример вызовет ошибку.
box.space.tester:format({{' ',type='number',is_nullable=false}})
box.space.tester:insert{nil,2}

В кортежах может быть больше полей, чем описано в операторе формата. Чтобы ограничить количество полей, необходимо указать для спейса элемент field_count.

В кортежах может быть меньше полей, чем описано в операторе формата, если пропущенные завершающие поля описаны с помощью is_nullable=true. Например, запрос ниже не приведет к ошибке формата:

box.space.tester:format({{'a',type='number'},{'b',type='number',is_nullable=true}})
box.space.tester:insert{2}

Можно использовать format для спейса, в котором уже определен формат, заменяя таким образом предыдущие определения при условии, что нет конфликта с существующими данными или определениями индекса.

Можно использовать format для того, чтобы изменить значение флага is_nullable. Пример ниже не вызовет ошибки – и не приведет к перестроению спейса.

box.space.tester:format({{' ',type='scalar',is_nullable=false}})
box.space.tester:format({{' ',type='scalar',is_nullable=true}})

Но обратное изменение значение is_nullable с true на false может вызвать перестроение и привести к ошибке, если уже есть кортежи с нулевыми значениями.

Пример:

box.space.tester:format({{name='surname',type='string'},{name='IDX',type='array'}})
box.space.tester:format({{name='surname',type='string',is_nullable=true}})

Можно использовать следующие варианты оператора:

  • пропуск и „name=“, и „type=“,
  • пропуск только „type=“,
  • добавление дополнительных фигурных скобок.

В следующем примере иллюстрируются все варианты, первый для поля с именем „x“, второй – для двух полей с именами „x“ и „y“.

box.space.tester:format({{name='x',type='scalar'}})
box.space.tester:format({{name='x',type='scalar'},{name='y',type='unsigned'}})

box.space.tester:format({{'x'}})
box.space.tester:format({{'x'},{'y'}})

-- типы
box.space.tester:format({{name='x'}})
box.space.tester:format({{name='x'},{name='y'}})

box.space.tester:format({{'x',type='scalar'}})
box.space.tester:format({{'x',type='scalar'},{'y',type='unsigned'}})

box.space.tester:format({{'x','scalar'}})
box.space.tester:format({{'x','scalar'},{'y','unsigned'}})

В следующем примере показывается создание спейса, определение формата для него со всеми возможными типа и вставка данных.

tarantool> box.schema.space.create('t')
---
- engine: memtx
  before_replace: 'function: 0x4019c488'
  on_replace: 'function: 0x4019c460'
  ck_constraint: []
  field_count: 0
  temporary: false
  index: []
  is_local: false
  enabled: false
  name: t
  id: 534
- created
...
tarantool> ffi = require('ffi')
---
...
tarantool> decimal = require('decimal')
---
...
tarantool> uuid = require('uuid')
---
...
tarantool> box.space.t:format({{name = '1', type = 'any'},
         >                     {name = '2', type = 'unsigned'},
         >                     {name = '3', type = 'string'},
         >                     {name = '4', type = 'number'},
         >                     {name = '5', type = 'double'},
         >                     {name = '6', type = 'integer'},
         >                     {name = '7', type = 'boolean'},
         >                     {name = '8', type = 'decimal'},
         >                     {name = '9', type = 'uuid'},
         >                     {name = 'a', type = 'scalar'},
         >                     {name = 'b', type = 'array'},
         >                     {name = 'c', type = 'map'}})
---
...
tarantool> box.space.t:create_index('i',{parts={2, type = 'unsigned'}})
---
- unique: true
  parts:
  - type: unsigned
    is_nullable: false
    fieldno: 2
  id: 0
  space_id: 534
  type: TREE
  name: i
...
tarantool> box.space.t:insert{{'a'}, -- any
         >                    1, -- unsigned
         >                    'W?', -- string
         >                    5.5, -- number
         >                    ffi.cast('double', 1), -- double
         >                    -0, -- integer
         >                    true, -- boolean
         >                    decimal.new(1.2), -- decimal
         >                    uuid.new(), -- uuid
         >                    true, -- scalar
         >                    {{'a'}}, -- array
         >                    {val=1}} -- map
---
- [['a'], 1, 'W?', 5.5, 1, 0, true, 1.2, 1f41e7b8-3191-483d-b46e-1aa6a4b14557, true, [['a']], {'val': 1}]
...

Имена, указанные с помощью оператора формата, можно использовать в space_object:get(), в space_object:create_index(), в tuple_object[field-name] и в tuple_object[field-path].

Если оператор формата не указан, то вернется таблица, которая использовалась при предыдущем вызове объект-спейса:format(оператор-формата). Например, после box.space.tester:format({{'x','scalar'}}), box.space.tester:format() вернет [{'name': 'x', 'type': 'scalar'}].

Formatting or reformatting a large space will cause occasional yields so that other requests will not be blocked. If the other requests cause an illegal situation such as a field value of the wrong type, the formatting or reformatting will fail.

Note regarding storage engine: vinyl supports formatting of non-empty spaces. Primary index definition cannot be formatted.

space_object:frommap()

object space_object
space_object:frommap(map[, option])

Конвертация ассоциативного массива в экземпляр кортежа или в таблицу. Ассоциативный массив должен состоять из пар «имя поля = значение». Имена полей и типы значений должны соответствовать именам и типам, ранее заданным для спейса с помощью space_object:format().

Параметры:
  • space_object (space_object) – ссылка на объект
  • map (field-value-pairs) – ряд пар «поле = значение» в любом порядке.
  • option (boolean) – единственный возможный параметр {table = true|false};
    если параметр не указан, или же {table = false}, то возвращается „cdata“ (то есть кортеж);
    если {table = true}, то возвращается таблица.
возвращает:

кортеж или таблица.
тип возвращаемого значения:
 

кортеж или таблица

Возможные ошибки: отсутствует объект спейса space_object, или в спейсе нет формата; «unknown field» (неизвестное поле).

Пример:

-- Создание формата с двумя полями под названиями 'a' и 'b'.
-- Создание спейса с таким форматом.
-- Создание кортежа на основе ассоциативного массива по данному спейсу.
-- Создание таблицы на основе ассоциативного массива по данному спейсу.
tarantool> format1 = {{name='a',type='unsigned'},{name='b',type='scalar'}}
---
...
tarantool> s = box.schema.create_space('test', {format = format1})
---
...
tarantool> s:frommap({b = 'x', a = 123456})
---
- [123456, 'x']
...
tarantool> s:frommap({b = 'x', a = 123456}, {table = true})
---
- - 123456
  - x
...

space_object:get()

object space_object
space_object:get(key)

Поиск кортежа в данном спейсе.

Параметры:
  • space_object (space_object) – ссылка на объект
  • key (scalar/table) – значение должно совпасть с индексным ключом, который может быть составным.
возвращает:

кортеж, ключ индекса в котором совпадает с key или nil.
тип возвращаемого значения:
 

tuple

Возможные ошибки:

Факторы сложности Размер индекса, тип индекса, количество индексов, к которым получен доступ, настройки журнала упреждающей записи (WAL).

Функция box.space...select вернет набор кортежей в виде Lua-таблицы; функция box.space...get вернет самое большее один кортеж. Можно получить первый кортеж в спейсе, добавив [1]. Таким образом, box.space.tester:get{1} эквивалентна box.space.tester:select{1}[1], если найден только один кортеж.

Пример:

box.space.tester:get{1}

Использование имен полей вместо номеров полей: в get() можно использовать имена полей, описанные в необязательном операторе space_object:format(). Это связано с тем, что функция get() возвращает объет, который можно использовать с большинством функций, описанных в Вложенный модуль box.tuple, включая tuple_object[field-name].

Например, может форматировать спейс tester с полем под названием x и использовать имя x в определении индекса:

box.space.tester:format({{name='x',type='scalar'}})
box.space.tester:create_index('I',{parts={'x'}})

Тогда если get или select вернут отдельный кортеж, можно сослаться на поле „x“ в кортеже по имени:

box.space.tester:get{1}['x']
box.space.tester:select{1}[1]['x']

space_object:insert()

object space_object
space_object:insert(tuple)

Вставка кортежа в спейс.

Параметры:
возвращает:

вставленный кортеж
тип возвращаемого значения:
 

tuple

Возможные ошибки:

  • ER_TUPLE_FOUND, если уже существует кортеж с тем же уникальным значением ключа.
  • ER_TRANSACTION_CONFLICT, если транзакция стала конфликтной в транзакционном режиме MVCC.

Пример:

tarantool> box.space.tester:insert{5000,'tuple number five thousand'}
---
- [5000, 'tuple number five thousand']
...

Для получения дополнительной информации о сценариях использования и типичных ошибках, см. Пример: использование операций с данными далее в разделе.

space_object:len()

object space_object
space_object:len()

Возврат количества кортежей в спейсе. Если сравнивать с count(), то len() работает быстрее, поскольку не сканирует весь спейс для подсчета кортежей.

Параметры:
возвращает:

Количество кортежей в спейсе.

Возможные ошибки:

Пример:

tarantool> box.space.tester:len()
---
- 2
...

Note regarding storage engine: vinyl supports len() but the result may be approximate. If an exact result is necessary then use count() or pairs():length().

space_object:on_replace()

object space_object
space_object:on_replace([trigger-function[, old-trigger-function]])

Создание «триггера замены». Функция-триггер trigger-function будет выполняться в случае операции replace() или insert(), или update(), или upsert(), или delete() над кортежем в спейсе <space-name>.

Параметры:
  • trigger-function (function) – функция, в которой будет триггер; подробнее о параметрах функции с триггером см. пример 2 ниже
  • old-trigger-function (function) – существующая функция-триггер, которую заменит новая trigger-function
возвращает:

nil или указатель функции

Если указаны параметры (nil, old-trigger-function), то старый триггер будет удален.

Если не указан ни один параметр, ответом будет список существующих функций с триггером.

Следует знать, что если активация триггера произошла в случае репликации или определенного вида подключения, функция может ссылаться на box.session.type().

Подробная информация о характеристиках триггера находится в разделе Триггеры.

См. также space_object:before_replace().

Пример 1:

tarantool> x = 0
         > function f ()
         >   x = x + 1
         > end
tarantool> box.space.my_space_name:on_replace(f)

Пример 2:

В функции с триггером может быть до 4 параметров:

  • (кортеж) старое значение до начала запроса,
  • (кортеж) новое значение после окончания выполнения запроса,
  • (строка) имя спейса,
  • (строка) тип запроса: INSERT (вставка), DELETE (удаление), UPDATE (обновление) или REPLACE (замена).

Например, следующий код вызывает вывод nil и INSERT при обработке запроса на вставку и вывод [1, 'Hi'] и DELETE при обработке запроса на удаление:

box.schema.space.create('space_1')
box.space.space_1:create_index('space_1_index',{})
function on_replace_function (old, new, s, op) print(old) print(op) end
box.space.space_1:on_replace(on_replace_function)
box.space.space_1:insert{1,'Hi'}
box.space.space_1:delete{1}

Пример 3:

Следующая серия запросов создаст спейс, создаст индекс, создаст функцию, которая увеличит содержимое счетчика, создаст триггер, сделает две вставки, удалит спейс и отобразит значение счетчика – 2, поскольку функция выполняется однократно после каждой вставки.

tarantool> s = box.schema.space.create('space53')
tarantool> s:create_index('primary', {parts = {{field = 1, type = 'unsigned'}}})
tarantool> function replace_trigger()
         >   replace_counter = replace_counter + 1
         > end
tarantool> s:on_replace(replace_trigger)
tarantool> replace_counter = 0
tarantool> t = s:insert{1, 'First replace'}
tarantool> t = s:insert{2, 'Second replace'}
tarantool> s:drop()
tarantool> replace_counter

Примечание

Так как всё, что выполняется в триггерах, уже находится в транзакции, не следует использовать в триггерных функциях on_replace и before_replace

  • транзакции,
  • yield-operations (explicit or not),
  • действия, которые не разрешено использовать в транзакциях (см. правило №2).

Пример:

tarantool> box.space.test:on_replace(fiber.yield)
tarantool> box.space.test:replace{1, 2, 3}
2020-02-02 21:22:03.073 [73185] main/102/init.lua txn.c:532 E> ER_TRANSACTION_YIELD: Transaction has been aborted by a fiber yield
---
- error: Transaction has been aborted by a fiber yield
...

space_object:before_replace()

object space_object
space_object:before_replace([trigger-function[, old-trigger-function]])

Создание «триггера замены». Функция-триггер trigger-function будет выполняться в случае операции replace() или insert(), или update(), или upsert(), или delete() над кортежем в спейсе <space-name>.

Параметры:
  • trigger-function (function) – функция, которая станет функцией-триггером; описание необязательных параметров для функций-триггеров см. в on_replace.
  • old-trigger-function (function) – существующая функция-триггер, которую заменит trigger-function
возвращает:

nil или указатель функции

Если указаны параметры (nil, old-trigger-function), старый триггер будет удален.

Если не указан ни один параметр, ответом будет список существующих функций-триггеров.

Следует знать, что если активация триггера произошла в случае репликации или определенного вида подключения, функция может ссылаться на box.session.type().

Подробная информация о характеристиках триггера находится в разделе Триггеры.

См. также space_object:on_replace().

Администраторы могут создавать триггеры замены с условием после замены on_replace() или до замены before_replace(). Если созданы оба типа, то все триггеры до замены before_replace выполняются до всех триггеров после замены on_replace. Функции для обоих типов триггеров on_replace и before_replace могут вносить изменения в базу данных, но только функции с триггерами до замены before_replace могут изменять кортеж, который будет заменен.

Поскольку функция-триггер до замены before_replace может вносить дополнительные изменения в старый кортеж, для нее также потребуются дополнительные ресурсы для вызова старого кортежа до внесения изменений. Таким образом, лучше использовать триггер после замены on_replace, если нет необходимости изменять старый кортеж. Тем не менее, это применимо только к движку memtx – что касается движка vinyl, такой вызов произойдет для любого типа триггера. (В memtx’е данные кортежа хранятся вместе с ключом индекса, поэтому нет необходимости в дополнительном поиске; для vinyl’а дело обстоит иначе, поэтому нужен дополнительный поиск.)

Если нет необходимости в дополнительных изменениях, следует использовать on_replace вместо before_replace. Как правило, before_replace используется только для определенных сценариев репликации – в части разрешения конфликтов.

Что случится после возврата значения, которое может вернуть функция-триггер before_replace, зависит от этого значения. А именно:

  • если нет возвращаемого значения, выполнение продолжается со вставкой|заменой нового значения;
  • если значение – nil, то кортеж будет удален;
  • если значение совпадает со старым, то функция on_replace не вызывается, и изменение данных не происходит. Возвращаемого значения в таком случае не будет.
  • если значение совпадает с новым, то считаем, что вызова функции before_replace не было;
  • если значение другое, выполнение продолжается со вставкой/заменой нового значения.

Тем не менее, если функция-триггер возвращает старый кортеж или вызовет run_triggers(false), это не повлияет на другие триггеры, активируемые в том же запросе вставки, обновления или замены.

Пример:

Далее представлены функции before_replace: не возвращает значение, возвращает nil, возвращает совпадающее со старым значение, возвращает совпадающее с новым значение, возвращает другое значение.

function f1 (old, new) return end
function f2 (old, new) return nil end
function f3 (old, new) return old end
function f4 (old, new) return new end
function f5 (old, new) return box.tuple.new({new[1],'b'}) end

space_object:pairs()

object space_object
space_object:pairs([key[, iterator]])

Search for a tuple or a set of tuples in the given space, and allow iterating over one tuple at a time. To search by the specific index, use the index_object:pairs() method.

Параметры:
  • space_object (space_object) – ссылка на объект
  • key (scalar/table) – значение должно совпасть с индексным ключом, который может быть составным
  • iterator – the iterator type. The default iterator type is „EQ“
  • after – a tuple or the position of a tuple (tuple_pos) after which pairs starts the search. You can pass an empty string or box.NULL to this option to start the search from the first tuple.
возвращает:

The iterator, which can be used in a for/end loop or with totable().

Возможные ошибки:

  • no such space
  • wrong type
  • ER_TRANSACTION_CONFLICT if a transaction conflict is detected in the MVCC transaction mode
  • iterator position is invalid

Факторы сложности: Размер индекса, тип индекса.

For information about iterators“ internal structures, see the «Lua Functional library» documentation.

Examples:

Below are few examples of using pairs with different parameters. To try out these examples, you need to bootstrap a Tarantool instance as described in Using data operations.

-- Insert test data --
tarantool> bands:insert{1, 'Roxette', 1986}
           bands:insert{2, 'Scorpions', 1965}
           bands:insert{3, 'Ace of Base', 1987}
           bands:insert{4, 'The Beatles', 1960}
           bands:insert{5, 'Pink Floyd', 1965}
           bands:insert{6, 'The Rolling Stones', 1962}
           bands:insert{7, 'The Doors', 1965}
           bands:insert{8, 'Nirvana', 1987}
           bands:insert{9, 'Led Zeppelin', 1968}
           bands:insert{10, 'Queen', 1970}
---
...

-- Select all tuples by the primary index --
tarantool> for _, tuple in bands:pairs() do
               print(tuple)
           end
[1, 'Roxette', 1986]
[2, 'Scorpions', 1965]
[3, 'Ace of Base', 1987]
[4, 'The Beatles', 1960]
[5, 'Pink Floyd', 1965]
[6, 'The Rolling Stones', 1962]
[7, 'The Doors', 1965]
[8, 'Nirvana', 1987]
[9, 'Led Zeppelin', 1968]
[10, 'Queen', 1970]
---
...

-- Select all tuples whose primary key values are between 3 and 6 --
tarantool> for _, tuple in bands:pairs(3, {iterator = "GE"}) do
             if (tuple[1] > 6) then break end
             print(tuple)
           end
[3, 'Ace of Base', 1987]
[4, 'The Beatles', 1960]
[5, 'Pink Floyd', 1965]
[6, 'The Rolling Stones', 1962]
---
...

-- Select all tuples after the specified tuple --
tarantool> for _, tuple in bands:pairs({}, {after={7, 'The Doors', 1965}}) do
               print(tuple)
           end
[8, 'Nirvana', 1987]
[9, 'Led Zeppelin', 1968]
[10, 'Queen', 1970]
---
...

space_object:put()

См. space_object:replace() / put().

space_object:rename()

object space_object
space_object:rename(space-name)

Переименование спейса.

Параметры:
возвращает:

nil

Возможные ошибки: space_object не существует

Пример:

tarantool> box.space.space55:rename('space56')
---
...
tarantool> box.space.space56:rename('space55')
---
...

space_object:replace() / put()

object space_object
space_object:replace(tuple)
space_object:put(tuple)

Вставка кортежа в спейс. Если уже существует кортеж с тем же первичным ключом, box.space...:replace() заменит существующий кортеж новым. Варианты синтаксиса (box.space...:replace() и box.space...:put()) приведут к одному результату, но последний иногда используется как противоположность box.space...:get().

Параметры:
возвращает:

вставленный кортеж
тип возвращаемого значения:
 

tuple

Возможные ошибки:

  • ER_TUPLE_FOUND, если уже существует другой кортеж с тем же уникальным значением ключа (это произойдет только в том случае, если есть уникальный вторичный индекс).
  • ER_TRANSACTION_CONFLICT, если транзакция стала конфликтной в транзакционном режиме MVCC.

Факторы сложности: Размер индекса, тип индекса, количество индексов, к которым получен доступ, настройки журнала упреждающей записи (WAL).

Пример:

box.space.tester:replace{5000, 'tuple number five thousand'}

Для получения дополнительной информации о сценариях использования и типичных ошибках, см. Пример: использование операций с данными далее в разделе.

space_object:run_triggers()

object space_object
space_object:run_triggers(true|false)

В тот момент, когда триггер определен, он активируется автоматически, то есть он будет исполняться. Триггеры replace можно отключить с помощью box.space.space-name:run_triggers(false) и повторно активировать с помощью box.space.space-name:run_triggers(true).

возвращает:nil

Пример:

Следующая серия запросов ассоциирует существующую функцию с именем F с существующим спейсом с именем T, ассоциирует функцию во второй раз с тем же спейсом (чтобы вызвать ее дважды), отключит все триггеры на T и удалит каждый триггер, заменив его на nil.

tarantool> box.space.T:on_replace(F)
tarantool> box.space.T:on_replace(F)
tarantool> box.space.T:run_triggers(false)
tarantool> box.space.T:on_replace(nil, F)
tarantool> box.space.T:on_replace(nil, F)

space_object:select()

object space_object
space_object:select([key[, options]])

Search for a tuple or a set of tuples in the given space by the primary key. To search by the specific index, use the index_object:select() method.

Примечание

Note that this method doesn’t yield. For details, see Cooperative multitasking.

Параметры:
  • space_object (space_object) – an object reference.
  • key (scalar/table) – a value to be matched against the index key, which may be multi-part.
  • options (table/nil) –

    none, any, or all of the same options that index_object:select() allows:

    • options.iterator – the iterator type. The default iterator type is „EQ“.
    • options.limit – the maximum number of tuples.
    • options.offset – the number of tuples to skip.
    • options.after – a tuple or the position of a tuple (tuple_pos) after which select starts the search. You can pass an empty string or box.NULL to this option to start the search from the first tuple.
    • options.fetch_pos – if true, the select method returns the position of the last selected tuple as the second value.

      Примечание

      The after and fetch_pos options are supported for the TREE index only.
возвращает:

This function might return one or two values:

  • The tuples whose primary-key fields are equal to the fields of the passed key. If the number of passed fields is less than the number of fields in the primary key, then only the passed fields are compared, so select{1,2} matches a tuple whose primary key is {1,2,3}.
  • (Optionally) If options.fetch_pos is set to true, returns a base64-encoded string representing the position of the last selected tuple as the second value. If no tuples are fetched, returns nil.
тип возвращаемого значения:
 
  • массив кортежей
  • (Optionally) string

Возможные ошибки:

  • no such space
  • wrong type
  • ER_TRANSACTION_CONFLICT if a transaction conflict is detected in the MVCC transaction mode
  • iterator position is invalid

Факторы сложности: Размер индекса, тип индекса

Examples:

Below are few examples of using select with different parameters. To try out these examples, you need to bootstrap a Tarantool instance as described in Using data operations.

-- Insert test data --
tarantool> bands:insert{1, 'Roxette', 1986}
           bands:insert{2, 'Scorpions', 1965}
           bands:insert{3, 'Ace of Base', 1987}
           bands:insert{4, 'The Beatles', 1960}
           bands:insert{5, 'Pink Floyd', 1965}
           bands:insert{6, 'The Rolling Stones', 1962}
           bands:insert{7, 'The Doors', 1965}
           bands:insert{8, 'Nirvana', 1987}
           bands:insert{9, 'Led Zeppelin', 1968}
           bands:insert{10, 'Queen', 1970}
---
...

-- Select a tuple by the specified primary key --
tarantool> bands:select(4)
---
- - [4, 'The Beatles', 1960]
...

-- Select maximum 3 tuples with the primary key value greater than 3 --
tarantool> bands:select({3}, {iterator='GT', limit = 3})
---
- - [4, 'The Beatles', 1960]
  - [5, 'Pink Floyd', 1965]
  - [6, 'The Rolling Stones', 1962]
...

-- Select maximum 3 tuples after the specified tuple --
tarantool> bands:select({}, {after = {4, 'The Beatles', 1960}, limit = 3})
---
- - [5, 'Pink Floyd', 1965]
  - [6, 'The Rolling Stones', 1962]
  - [7, 'The Doors', 1965]
...

-- Select first 3 tuples and fetch a last tuple's position --
tarantool> result, position = bands:select({}, {limit = 3, fetch_pos = true})
---
...
-- Then, pass this position as the 'after' parameter --
tarantool> bands:select({}, {limit = 3, after = position})
---
- - [4, 'The Beatles', 1960]
  - [5, 'Pink Floyd', 1965]
  - [6, 'The Rolling Stones', 1962]
...

Примечание

You can get a field from a tuple both by the field number and field name. See example: using field names instead of field numbers.

space_object:stat()

object space_object
space_object:stat()

Get statistics on memory usage by the space.

Returns a table with the cumulative statistics on the memory usage by tuples in the space. Statistics are grouped by arena types: memtx or malloc. For each arena type, the return table includes tuple memory usage statistics listed in the tuple_object.info() reference.

Примечание

Memory usage statistics are shown only for the memtx storage engine. For other types of spaces, an empty table is returned.

Параметры:
Return:

space memory usage statistics
Rtype:

table

Possible errors: space_object does not exist.

Example:

tarantool> box.space.tester:stat()
---
- tuple:
    memtx:
      waste_size: 145
      data_size: 235
      header_size: 36
      field_map_size: 24
    malloc:
      waste_size: 0
      data_size: 0
      header_size: 0
      field_map_size: 0
...

space_object:truncate()

object space_object
space_object:truncate()

Удаление всех кортежей. Метод выполняется в фоновом режиме и не блокирует последующие запросы.

Параметры:

Факторы сложности: Размер индекса, тип индекса, количество кортежей, к которым получен доступ.

возвращает:nil

Метод truncate может вызвать только тот пользователь, который создал спейс, или другой пользователь через функцию setuid, созданную пользователем, который создал спейс. Более подробную информацию о функциях setuid можно получить в справочнике по for box.schema.func.create().

Примечание

В версиях Tarantool старше v. 2.10.0 не следует вызывать truncate из транзакции. Подробности в тикете gh-6123.

Пример:

tarantool> box.space.tester:truncate()
---
...
tarantool> box.space.tester:len()
---
- 0
...

space_object:update()

object space_object
space_object:update(key, {{operator, field_identifier, value}, ...})

Обновление кортежа.

Функция update поддерживает операции над полями — присваивание, арифметические операции (если поле числовое), вырезание и вставку фрагментов поля, удаление или вставку поля. Несколько операций можно объединить в отдельный запрос обновления, и в таком случае они будут выполняться атомарно и последовательно. Для каждой операции необходимо указать идентификатор поля, как правило числовой. При выполнении нескольких операций номер поля для каждой операции принимается относительно последнего состояния кортежа, то есть как если бы уже были выполнены все предыдущие операции в обновлении с несколькими операциями. Другими словами, всегда лучше объединить несколько вызовов update в один без изменений семантики.

Возможные операторы:

  • + для сложения; значения должны быть числовыми, например, unsigned или decimal
  • - для вычитания; значения должны быть числовыми
  • & для операции побитового И; значения должны быть числовыми типа unsigned
  • | для операции побитового ИЛИ; значения должны быть числовыми типа unsigned
  • ^ для операции побитового исключающего ИЛИ; значения должны быть числовыми типа unsigned
  • : для разделения строк.
  • ! для вставки нового поля.
  • # для удаления.
  • = для присваивания.

Возможные операторы:

  • Положительный номер позиции поля. Первое поле — 1, второе — 2 и так далее.
  • Отрицательный номер позиции поля. Последнее поле — −1, предпоследнее — −2 и так далее. Другими словами: (#tuple + отрицательный номер позиции поля + 1).
  • Имя. Если спейс был отформатирован с помощью space_object:format(), здесь может быть строка с именем поля.
Параметры:
  • space_object (space_object) – ссылка на объект
  • key (scalar/table) – значения поля первичного ключа, которые должны возвращаться в виде Lua-таблицы, если ключ составной
  • operator (string) – тип операции, представленный строкой
  • field_identifier (number-or-string) – к какому полю применяется операция.
  • value (lua_value) – какое значение применяется
возвращает:
  • обновленный кортеж
  • nil, если ключ не найден
тип возвращаемого значения:
 

кортеж или nil

Возможные ошибки:

Факторы сложности Размер индекса, тип индекса, количество индексов, к которым получен доступ, настройки журнала упреждающей записи (WAL).

Таким образом, в инструкции:

s:update(44, {{'+', 1, 55 }, {'=', 3, 'x'}})

значение первичного ключа равно 44, заданы операторы '+' и '=', что означает прибавление значение к полю, а затем присваивание значения полю, первое затронутое поле – это поле 1, к нему прибавляется значение 55, второе затронутое поле – это поле 3, ему присваивается значение 'x'.

Пример:

Предположим, что изначально есть спейс под названием tester с первичным индексом, тип которого – unsigned. Есть один кортеж с полем №1 field[1] = 999 и полем №2 field[2] = 'A'.

В обновлении:
box.space.tester:update(999, {{'=', 2, 'B'}})
Первый аргумент – это tester, то есть обновление происходит в спейсе tester. Второй аргумент – 999, то есть затронутый кортеж определяется по значению первичного ключа = 999. Третий аргумент – =, то есть будет одна операция – присваивание полю. Четвертый аргумент – 2, то есть будет затронуто поле №2 field[2]. Пятый аргумент – 'B', то есть содержимое field[2] изменится на 'B'. Таким образом, после данного обновления field[1] = 999, а field[2] = 'B'.

В обновлении:
box.space.tester:update({999}, {{'=', 2, 'B'}})
Аргументы повторяются за исключением того, что ключ передается в виде Lua-таблицы (в фигурных скобках). В этом нет необходимости, если первичный ключ содержит только одно поле, но было бы необходимо, если бы в первичном ключе было больше одного поля. Таким образом, после данного обновления field[1] = 999, а field[2] = 'B' (без изменений).

В обновлении:
box.space.tester:update({999}, {{'=', 3, 1}})
Аргументы повторяются за исключением того, что четвертым аргументом будет 3, то есть будет затронуто поле №3 field[3]. Ничего страшного, что до этого поле field[3] не существовало. Оно добавится. Таким образом, после данного обновления field[1] = 999, field[2] = 'B', field[3] = 1.

В обновлении:
box.space.tester:update({999}, {{'+', 3, 1}})
Аргументы повторяются за исключением того, что третьим аргументом будет '+', то есть будет операция добавления, а не присваивания. Поскольку``field[3]`` ранее содержало значение 1, это означает, что к 1 прибавится 1. Таким образом, после данного обновления field[1] = 999, field[2] = 'B', field[3] = 2.

В обновлении:
box.space.tester:update({999}, {{'|', 3, 1}, {'=', 2, 'C'}})
Основная идея состоит в том, чтобы изменить одновременно два поля. Форматами будут '|' и =, то есть имеем две операции: ИЛИ и присваивание. Четвертый и пятый аргументы означают, что над полем field[3] проводится операция ИЛИ со значением 1. Седьмой и восьмой аргументы означают, что полю field[2] присваивается 'C'. Таким образом, после данного обновления field[1] = 999, field[2] = 'C', field[3] = 3.

В обновлении:
box.space.tester:update({999}, {{'#', 2, 1}, {'-', 2, 3}})
Основная идея состоит в том, чтобы удалить поле field[2], а затем вычесть 3 из field[3]. Но после удаления, произойдет перенумерация, поэтому поле field[3] становится field[2] до того, как мы вычтем из него 3, вот почему седьмым аргументом будет 2, а не 3. Таким образом, после данного обновления field[1] = 999, field[2] = 0.

В обновлении:
box.space.tester:update({999}, {{'=', 2, 'XYZ'}})
Создаем длинную строку, чтобы в следующем примере сработало разделение. Таким образом, после данного обновления field[1] = 999, field[2] = 'XYZ'.

В обновлении:
box.space.tester:update({999}, {{':', 2, 2, 1, '!!'}})
Третьим аргументом будет ':', то есть это пример разделения. Четвертым аргументом будет 2, поскольку изменение произойдет в поле field[2]. Пятым аргументом будет 2, поскольку удаление начнется со второго байта. Шестым аргументом будет 1, количество удаляемых байтов – 1. Седьмым аргументом будет '!!', поскольку в данном положении будет добавляться '!!'. Таким образом, после данного обновления field[1] = 999, field[2] = 'X!!Z'.

Для получения дополнительной информации о сценариях использования и типичных ошибках, см. Пример: использование операций с данными далее в разделе.

Начиная с версии Tarantool 2.3 кортеж можно обновить с помощью JSON-путей.

space_object:upsert()

object space_object
space_object:upsert({tuple}, {{operator, field_identifier, value}, ...})

Обновить или вставить кортеж.

Если уже существует кортеж, который совпадает с ключевыми полями tuple, запрос приведет к тому же результату, что и space_object:update(), и используется параметр {{operator, field_identifier, value}, ...}. Если нет кортежа, который совпадает с ключевыми полями tuple, запрос приведет к тому же результату, что и space_object:insert(), и используется параметр {tuple}. Однако, в отличие от insert или update, upsert не считывает кортеж и не выполняет проверку на ошибки перед возвратом — это функциональная особенность, которая повышает производительность, но требует большей осторожности от пользователя.

Параметры:
  • space_object (space_object) – ссылка на объект
  • tuple (table/tuple) – вставляемый по умолчанию кортеж, если не найдет аналог
  • operator (string) – тип операции, представленный строкой
  • field_identifier (number) – к какому полю применяется операция
  • value (lua_value) – какое значение применяется
возвращает:

null

Возможные ошибки:

  • Нельзя изменять поле первичного ключа.
  • Нельзя проводить операцию upsert в спейсе, в котором есть уникальный вторичный индекс.
  • ER_TRANSACTION_CONFLICT, если транзакция стала конфликтной в транзакционном режиме MVCC.

Факторы сложности: Размер индекса, тип индекса, количество индексов, к которым получен доступ, настройки журнала упреждающей записи (WAL).

Пример:

box.space.tester:upsert({12,'c'}, {{'=', 3, 'a'}, {'=', 4, 'b'}})

Для получения дополнительной информации о сценариях использования и типичных ошибках, см. Пример: использование операций с данными далее в разделе.

space_object extensions

You can extend space_object with custom functions as follows:

  1. Create a Lua function.
  2. Add the function name to a predefined global variable box.schema.space_mt, which has the table type. Adding to box.schema.space_mt makes the function available for all spaces.
  3. Call the function on the space_object: space_object:function-name([parameters]).

Alternatively, you can make a user-defined function available for only one space by calling getmetatable(space_object) and then adding the function name to the meta table.

See also: index_object extensions.

Пример:

-- Доступный для любого спейса, без параметров.
-- После таких запросов значение глобальной переменной global_variable будет 6.
box.schema.space.create('t')
box.space.t:create_index('i')
global_variable = 5
function f(space_arg) global_variable = global_variable + 1 end
box.schema.space_mt.counter = f
box.space.t:counter()

box.space.create_check_constraint()

Предупреждение

This function was removed in 2.11.0. The check constraint mechanism is replaced with the new tuple constraints. Learn more about tuple constraints in Constraints.

object space_object
space_object:create_check_constraint(check_constraint_name, expression)

Создание проверочного ограничения. Проверочное ограничение — это требование, которое должно соблюдаться при вставке или обновлении кортежа в спейсе. Проверочные ограничения, созданные с помощью space_object:create_check_constraint действуют так же, как проверочные ограничения, которые были созданы при помощи оператора SQL CHECK() в выражении CREATE TABLE.

Параметры:
возвращает:

объект проверочного ограничения
тип возвращаемого значения:
 

check_constraint_object

Спейс должен быть форматирован с помощью space_object:format(), чтобы выражение могло содержать имена полей. Спейс должен быть пустым. Спейс не должен быть системным.

Выражение должно возвращать true или false и должно быть детерминированным. Это может быть любое SQL-выражение (не Lua), которое содержит имена полей, встроенные имена функций, литералы и операторы. Не подзапросы. Если имя поля содержит символы нижнего регистра, его следует заключить в «двойные кавычки».

Проверка ограничений производится перед выполнением запроса, одновременно с Lua-триггерами before_replace. При наличии двух и более проверочных ограничений или триггеров before_replace они упорядочиваются по времени создания. (Это изменение предыдущего поведения проверочных ограничений, которое вызывало проверку до формирования кортежа).

Проверочные ограничения можно удалить с помощью space_object.ck_constraint.check_constraint_name:drop().

Проверочные ограничения можно отключить с помощью space_object.ck_constraint.check_constraint_name:enable(false) или check_constraint_object:enable(false). Проверочные ограничения можно включить с помощью space_object.ck_constraint.check_constraint_name:enable(true) или check_constraint_object:enable(true). По умолчанию, проверочное ограничение включено, то есть при выполнении запроса производится проверка, но его можно отключить, то есть проверка производиться не будет.

В процессе восстановления, например при запуске Tarantool-сервера, проверка производится, только если указан параметр force_recovery.

Пример:

box.schema.space.create('t')
box.space.t:format({{name = 'f1', type = 'unsigned'},
                    {name = 'f2', type = 'string'},
                    {name = 'f3', type = 'string'}})
box.space.t:create_index('i')
box.space.t:create_check_constraint('c1', [["f2" > 'A']])
box.space.t:create_check_constraint('c2',
                        [["f2"=UPPER("f3") AND NOT "f2" LIKE '__']])
-- Этот запрос вставки не выполнится, выражение с ограничением c1 возвращает false
box.space.t:insert{1, 'A', 'A'}
-- Этот запрос вставки не выполнится, выражение с ограничением c2 возвращает false
box.space.t:insert{1, 'B', 'c'}
-- Этот запрос вставки выполнится, оба выражения с ограничениями возвращают true
box.space.t:insert{1, 'B', 'b'}
-- Этот запрос обновления не выполнится, выражение с ограничением c2 возвращает false
box.space.t:update(1, {{'=', 2, 'xx'}, {'=', 3, 'xx'}})

Список проверочных ограничений представлен в box.space._ck_constraint.

space_object:enabled

object space_object
space_object.enabled

Определение активности спейса. Значение false указывает на отсутствие индекса.

space_object:field_count

object space_object
space_object.field_count

Необходимость подсчета полей всех кортежей в спейсе, который можно изначально задать следующим образом:

box.schema.space.create(..., {
    ... ,
    field_count = *field_count_value* ,
    ...
})

По умолчанию, будет использоваться значение 0, что указывает на отсутствие необходимости подсчета полей.

Пример:

tarantool> box.space.tester.field_count
---
- 0
...

space_object.id

object space_object
space_object.id

Порядковый номер спейса. На спейс можно ссылаться либо по имени, либо по номеру. Таким образом, если идентификатором спейса tester будет id = 800, то box.space.tester:insert{0} и box.space[800]:insert{0} представляют собой равнозначные запросы.

Пример:

tarantool> box.space.tester.id
---
- 512
...

space_object.index

object space_object
index

Контейнер для всех определенных индексов. Есть Lua-объект типа box.index с методами поиска кортежей и итерации по ним в заданном порядке.

Чтобы сбросить, use box.stat.reset().

тип возвращаемого значения:
 таблица

Пример:

-- проверка количества индексов для спейса 'tester'
tarantool> local counter=0; for i=0,#box.space.tester.index do
  if box.space.tester.index[i]~=nil then counter=counter+1 end
  end; print(counter)
1
---
...
-- проверка, что тип индекса -- первичный 'primary'
tarantool> box.space.tester.index.primary.type
---
- TREE
...

box.space._cluster

box.space._cluster

_cluster – это системный спейс для поддержки функции репликации.

box.space._func

box.space._func

A system space containing functions created using box.schema.func.create(). If a function’s definition is specified in the body option, this function is persistent. In this case, its definition is stored in a snapshot and can be recovered if the server restarts.

Примечание

Представление системного спейса _func — _vfunc.

box.space._index

box.space._index

_index – это системный спейс.

Кортежи в данном спейсе включают в себя следующие поля:

  • id (= идентификатор спейса),
  • iid (= номер индекса в спейсе),
  • name,
  • type,
  • opts (например, уникальная опция), [tuple-field-no, tuple-field-type …].

Вот что при обычной установке включает в себя спейс _index:

tarantool> box.space._index:select{}
---
- - [272, 0, 'primary', 'tree', {'unique': true}, [[0, 'string']]]
  - [280, 0, 'primary', 'tree', {'unique': true}, [[0, 'unsigned']]]
  - [280, 1, 'owner', 'tree', {'unique': false}, [[1, 'unsigned']]]
  - [280, 2, 'name', 'tree', {'unique': true}, [[2, 'string']]]
  - [281, 0, 'primary', 'tree', {'unique': true}, [[0, 'unsigned']]]
  - [281, 1, 'owner', 'tree', {'unique': false}, [[1, 'unsigned']]]
  - [281, 2, 'name', 'tree', {'unique': true}, [[2, 'string']]]
  - [288, 0, 'primary', 'tree', {'unique': true}, [[0, 'unsigned'], [1, 'unsigned']]]
  - [288, 2, 'name', 'tree', {'unique': true}, [[0, 'unsigned'], [2, 'string']]]
  - [289, 0, 'primary', 'tree', {'unique': true}, [[0, 'unsigned'], [1, 'unsigned']]]
  - [289, 2, 'name', 'tree', {'unique': true}, [[0, 'unsigned'], [2, 'string']]]
  - [296, 0, 'primary', 'tree', {'unique': true}, [[0, 'unsigned']]]
  - [296, 1, 'owner', 'tree', {'unique': false}, [[1, 'unsigned']]]
  - [296, 2, 'name', 'tree', {'unique': true}, [[2, 'string']]]
---
...

Представление системного спейса _index — _vindex.

box.space._vindex

box.space._vindex

Представление системного спейса _index — _vindex.

box.space._priv

box.space._priv

_priv – это системный спейс, где хранятся права.

Кортежи в данном спейсе включают в себя следующие поля:

  • числовой идентификатор пользователя, который выдал права («grantor_id»),
  • числовой идентификатор пользователя, который получил права («grantee_id»),
  • тип объекта: „space“, „index“, „function“, „sequence“, „user“, „role“, или „universe“,
  • числовой идентификатор объекта,
  • тип операции: «read» = 1, «write» = 2, «execute» = 4, «create» = 32, «drop» = 64, «alter» = 128, или их комбинация, например «read,write,execute».

Подробнее о правах пользователя см. в разделе Управление доступом.

Представление системного спейса _priv — _vpriv.

box.space._vpriv

box.space._vpriv

Представление системного спейса _priv — _vpriv.

box.space._schema

box.space._schema

_schema – это системный спейс.

Этот спейс включает в себя следующие кортежи:

  • version: version information for this Tarantool instance.
  • replicaset_name (since 3.0.0): the name of the replica set to which this instance belongs.
  • replicaset_uuid (since 3.0.0): the instance’s replica set UUID. In version 3.0.0, the field was renamed from cluster to replicaset_uuid.
  • max_id (deprecated since 2.11.1): the maximal space ID. Use the box.space._space.index[0]:max() function instead.
  • once...: tuples that correspond to specific box.once() blocks from the instance’s initialization file. The first field in these tuples contains the key value from the corresponding box.once() block prefixed with „once“ (for example, oncehello), so you can easily find a tuple that corresponds to a specific box.once() block.

Пример:

In the example, the _schema space contains two box.once objects – oncebye and oncehello.

app:instance001> box.space._schema:select{}
---
- - ['oncebye']
  - ['oncehello']
  - ['replicaset_name', 'replicaset001']
  - ['replicaset_uuid', '72d2d9bf-5d9f-48c4-ba80-9d657e128fee']
  - ['version', 3, 1, 0]
...

box.space._sequence

box.space._sequence

_sequence – это системный спейс для поддержки последовательностей. Он содержит персистентную информацию, определенную с помощью box.schema.sequence.create() или sequence_object:alter().

Представление системного спейса _sequence — _vsequence.

box.space._sequence_data

box.space._sequence_data

_sequence_data – это системный спейс для поддержки последовательностей.

Каждый кортеж в спейсе _sequence_data содержит два поля:

  • идентификатор последовательности и
  • последнее значение, возвращенное генератором последовательностей (временная информация).

Не гарантируется, что этот спейс будет обновляться сразу же после каждого запроса на изменение данных.

box.space._space

box.space._space

_space – это системный спейс. Он содержит информацию о всех спейсах, хранящихся в данном экземпляре Tarantool - как системные, так и созданные пользователями.

Кортежи в данном спейсе включают в себя следующие поля:

  • id,
  • owner (= идентификатор пользователя, которому принадлежит спейс),
  • name, engine, field_count,
  • flags (например, временный),
  • format (как задано с помощью оператора формата).

Эти поля задаются во время создания спейса с помощью box.schema.space.create().

Представление системного спейса _space — _vspace.

Пример №1:

Следующая функция отобразит все простые поля во всех кортежах спейса _space.

function example()
  local ta = {}
  local i, line
  for k, v in box.space._space:pairs() do
    i = 1
    line = ''
    while i <= #v do
      if type(v[i]) ~= 'table' then
        line = line .. v[i] .. ' '
      end
    i = i + 1
    end
    table.insert(ta, line)
  end
  return ta
end

Вот что при обычной установке вернет example():

tarantool> example()
---
- - '272 1 _schema memtx 0  '
  - '280 1 _space memtx 0  '
  - '281 1 _vspace sysview 0  '
  - '288 1 _index memtx 0  '
  - '296 1 _func memtx 0  '
  - '304 1 _user memtx 0  '
  - '305 1 _vuser sysview 0  '
  - '312 1 _priv memtx 0  '
  - '313 1 _vpriv sysview 0  '
  - '320 1 _cluster memtx 0  '
  - '512 1 tester memtx 0  '
  - '513 1 origin vinyl 0  '
  - '514 1 archive memtx 0  '
...

Пример №2:

Следующий набор запросов создаст спейс, используя box.schema.space.create() с оператором формата, затем выберет кортеж из _space для нового спейса. Этот пример иллюстрирует стандартное применение оператора format с использованием рекомендованных имен и типов данных для полей.

tarantool> box.schema.space.create('TM', {
         >   id = 12345,
         >   format = {
         >     [1] = {["name"] = "field_1"},
         >     [2] = {["type"] = "unsigned"}
         >   }
         > })
---
- index: []
  on_replace: 'function: 0x41c67338'
  temporary: false
  id: 12345
  engine: memtx
  enabled: false
  name: TM
  field_count: 0
- created
...
tarantool> box.space._space:select(12345)
---
- - [12345, 1, 'TM', 'memtx', 0, {}, [{'name': 'field_1'}, {'type': 'unsigned'}]]
...

box.space._vspace

box.space._vspace

Представление системного спейса _space — _vspace.

box.space._space_sequence

box.space._space_sequence

_space_sequence is a system space. It contains connections between spaces and sequences.

Tuples in this space contain the following fields:

  • id (unsigned) – space id
  • sequence_id (unsigned) – id of the attached sequence
  • is_generated (boolean) – true if the sequence was created automatically via a space:create_index('pk', {sequence = true}) call
  • field (unsigned) – id of the space field to which the sequence is attached.
  • path (string) – path to the data within the field that is set using the attached sequence.

The system space view for _space_sequence is _vspace_sequence.

Example

-- Create a sequence --
box.schema.sequence.create('id_seq',{min=1000, start=1000})
-- Create a space --
box.schema.space.create('customers')

-- Create an index that uses the sequence --
box.space.customers:create_index('primary',{ sequence = 'id_seq' })

-- Create a space --
box.schema.space.create('orders')

-- Create an index that uses an auto sequence --
box.space.orders:create_index( 'primary', { sequence = true })

-- Check the connections between spaces and sequences
box.space._space_sequence:select{}
--[[
---
- - [512, 1, false, 0, '']
  - [513, 2, true, 0, '']
...
--]]

box.space._vspace_sequence

box.space._vspace_sequence

_vspace_sequence is the system space view for _space.

box.space._user

box.space._user

_user is a system space where user names and password hashes are stored. Learn more about Tarantool’s access control system from the Управление доступом topic.

Кортежи в данном спейсе включают в себя следующие поля:

  • a numeric id of the tuple («id»)
  • a numeric id of the tuple’s creator
  • a name
  • a type: „user“ or „role“
  • (optional) a password hash
  • (optional) an array of previous authentication data
  • (optional) a timestamp of the last password update

В спейсе _user есть пять специальных кортежей: „guest“, „admin“, „public“, „replication“ и „super“.

Имя ID Тип Описание
guest 0 user (пользователь) Default user when connecting remotely. Usually, an untrusted user with few privileges.
admin 1 user (пользователь) Default user when using Tarantool as a console. Usually, an administrative user with all privileges.
public 2 роль Заданная роль, которая автоматически выдается новым пользователям при их создании методом box.schema.user.create(имя-пользователя). Таким образом, лучше всего выдать права на чтение „read“ спейса „t“ каждому когда-либо созданному пользователю с помощью box.schema.role.grant('public','read','space','t').
replication 3 роль Заданная роль, выдаваемая пользователем „admin“ другим пользователям для использования функций репликации.
super 31 роль Заданная роль, выдаваемая пользователем „admin“ другим пользователям для получения всех прав на все объекты. Для роли „super“ такие права выданы на „universe“: чтение, запись, выполнение, создание, удаление, изменение.

To select a tuple from the _user space, use box.space._user:select(). In the example below, select is executed for a user with id = 0. This is the „guest“ user that has no password.

tarantool> box.space._user:select{0}
---
- - [0, 1, 'guest', 'user']
...

Предупреждение

To change tuples in the _user space, do not use ordinary box.space functions for insert, update, or delete. Learn more from Managing users.

Представление системного спейса _user — _vuser.

box.space._vuser

box.space._vuser

Представление системного спейса _user — _vuser.

box.space._ck_constraint

box.space._ck_constraint

_ck_constraint — это системный спейс, в котором хранятся проверочные ограничения.

Кортежи в данном спейсе включают в себя следующие поля:

  • числовой идентификатор спейса («space_id»),
  • имя,
  • откладывается ли проверка («is_deferred»),
  • язык выражения, например „SQL“,
  • выражение («code»).

Пример:

tarantool> box.space._ck_constraint:select()
---
- - [527, 'c1', false, 'SQL', '"f2" > ''A''']
  - [527, 'c2', false, 'SQL', '"f2" == UPPER("f3") AND NOT "f2" LIKE ''__''']
...

box.space._collation

box.space._collation

_collation — это системный спейс со списком видов сортировки. Предусмотрены более 270 видов сортировки, и пользователи могут добавлять новые. Один из примеров:

tarantool> box.space._collation:select(239)
---
- - [239, 'unicode_uk_s2', 1, 'ICU', 'uk', {'strength': 'secondary'}]
...

Пояснения по полям в примере: id = 239, то есть первичный ключ в Tarantool равен 239; name = „unicode_uk_s2“, в соответствии с соглашениями по именованию в Tarantool это сортировка по Юникоду + для региона uk + значение strength 2 уровня; owner = 1, то есть пользователь уровня admin; type = „ICU“, то есть применяются правила библиотеки Международных компонентов для Юникода; locale = „uk“, то есть используются настройки для региона Украина; opts = „strength:secondary“, то есть при сортировке учитывается вес первого и второго уровней.

Представление системного спейса _collation — _vcollation.

box.space._vcollation

box.space._vcollation

Представление системного спейса _collation — _vcollation.

Представления системных спейсов

Представление системного спейса (или „sysview“) — копия системного спейса с доступом только для чтения.

The system space views and the system spaces that they are associated with are:
_vcollation, a view of _collation,
_vfunc, a view of _func,
_vindex, a view of _index,
_vpriv, a view of _priv,
_vsequence, a view of _sequence,
_vspace, a view of _space,
_vspace_sequence, a view of _space_sequence,
_vuser, a view of _user.

Структура кортежей в представлении системного спейса идентична структуре кортежам соответствующего спейса. Однако права там обычно отличаются. По умолчанию у обычных пользователей в большинстве системных спейсов нет никаких прав, однако в представлениях системных спейсов у них есть право чтения.

Ситуация по умолчанию:
* У роли „public“ есть право „read“ во всех представлениях системных спейсов, потому что именно так обстоят дела при создании базы данных.
* У всех пользователей есть роль „public“, потому что она назначается им автоматически при выполнении box.schema.user.create().
* В представлении системного спейса будут содержаться кортежи соответствующего системного спейса, только если у пользователя есть право, связанное с объектом, упомянутом в кортеже.
Как результат, если администраторы не изменят права, у остальных пользователей не будет доступа к системному спейсу, но будет доступ к представлению системного спейса, где видны только доступные им объекты.

Например, пользователь „admin“ обычно имеет полный доступ к спейсу _space, поэтому и _vspace для него выглядит как _space. А „guest“ имеет только право на чтение _vspace, так что _vspace для него содержит меньше кортежей, чем _space. Поэтому в большинстве систем пользователю „guest“ чтобы получить список спейсов, следует делать выборку из _vspace.

Пример

В этом примере рассмотрим разницу между _vuser и _user. Представление _vuser содержит только кортежи, которые доступны текущему пользователю. Если же у пользователя есть полный набор прав (как у пользователя „admin“), то содержимое _vuser совпадает с содержимым _user.

To see how _vuser works, connect to a Tarantool database remotely via net.box and select all tuples from the _user space, both when the „guest“ user is and is not allowed to read from the database.

Запустите Tarantool и назначьте права read, write и execute пользователю guest:

tarantool> box.cfg{listen = 3301}
---
...
tarantool> box.schema.user.grant('guest', 'read,write,execute', 'universe')
---
...

Переключитесь на другой терминал, подключитесь к экземпляру Tarantool и выберите все кортежи из спейса _user:

tarantool> conn = require('net.box').connect(3301)
---
...
tarantool> conn.space._user:select{}
---
- - [0, 1, 'guest', 'user', {}]
  - [1, 1, 'admin', 'user', {}]
  - [2, 1, 'public', 'role', {}]
  - [3, 1, 'replication', 'role', {}]
  - [31, 1, 'super', 'role', {}]
...

Будут показаны те же пользователи, как если бы вы отправили запрос из своего экземпляра Tarantool как „admin“.

Переключитесь на первый терминал и отзовите право read у пользователя „guest“:

tarantool> box.schema.user.revoke('guest', 'read', 'universe')
---
...

Переключитесь на другой терминал, остановите сессию (чтобы остановить tarantool, нажмите Ctrl+C или Ctrl+D), запустите и подключитесь снова, а затем повторите запрос conn.space._user:select{}. Доступ будет запрещен:

tarantool> conn.space._user:select{}
---
- error: Read access to space '_user' is denied for user 'guest'
...

Однако если вместо этого сделать select из _vuser, появятся данные пользователей, доступные пользователю „guest“:

tarantool> conn.space._vuser:select{}
---
- - [0, 1, 'guest', 'user', {}]
...

box.space._session_settings

box.space._session_settings

A temporary system space with settings that affect behavior, particularly SQL behavior, for the current session. It uses a special engine named „service“. Every „service“ tuple is created on the fly, that is, new tuples are made every time _session_settings is accessed. Every settings tuple has two fields: name (the primary key) and value. The tuples“ names and default values are:

  • sql_default_engine: default storage engine for new SQL tables. Default: memtx.
  • sql_full_column_names: use full column names in SQL result set metadata. Default: false.
  • sql_full_metadata: whether SQL result set metadata includes more than just name and type. Default:false.
  • sql_parser_debug: show parser steps for following statements. Default: false.
  • sql_recursive_triggers: whether a triggered statement can activate a trigger. Default: true.
  • sql_reverse_unordered_selects: return result rows in reverse order if there is no ORDER BY clause. Default: false.
  • sql_select_debug: show execution steps during SELECT. Default:false.
  • sql_seq_scan: allow sequential scans in SQL SELECT. Default: true.
  • sql_vdbe_debug: for internal use. Default:false.
  • sql_defer_foreign_keys (removed in 2.11.0): whether foreign-key checks can wait till commit. Default: false.
  • error_marshaling_enabled (removed in 2.10.0): whether error objects have a special structure. Default: false.

Three requests are possible: select, get and update. For example, after s = box.space._session_settings, s:select('sql_default_engine') probably returns {'sql_default_engine', 'memtx'}, and s:update('sql_default_engine', {{'=', 'value', 'vinyl'}}) changes the default engine to „vinyl“.
Updating sql_parser_debug or sql_select_debug or sql_vdbe_debug has no effect unless Tarantool was built with -DCMAKE_BUILD_TYPE=Debug. To check if this is so, look at require('tarantool').build.target.

Вложенный модуль box.stat

Вложенный модуль box.stat предоставляет доступ к статистике Tarantool по запросам и использованию сети.

Below is a list of all box.stat functions.

Name Use
box.stat() Show request statistics
box.stat.net() Show network activity
box.stat.memtx() Show memtx storage engine activity
box.stat.vinyl() Show vinyl storage engine activity
box.stat.reset() Reset the statistics

box.stat()

box.stat()

Shows the total number of requests since startup and the average number of requests per second, broken down by request type.

Return:

in the tables that box.stat() returns:

  • total: total number of requests processed per second since the server started
  • rps: average number of requests per second in the last 5 seconds.

ERROR is the count of requests that resulted in an error.

Example:

tarantool> box.stat() -- return 15 tables
---
- DELETE:
    total: 0
    rps: 0
  COMMIT:
    total: 0
    rps: 0
  SELECT:
    total: 12
    rps: 0
  ROLLBACK:
    total: 0
    rps: 0
  INSERT:
    total: 6
    rps: 0
  EVAL:
    total: 0
    rps: 0
  ERROR:
    total: 0
    rps: 0
  CALL:
    total: 0
    rps: 0
  BEGIN:
    total: 0
    rps: 0
  PREPARE:
    total: 0
    rps: 0
  REPLACE:
    total: 0
    rps: 0
  UPSERT:
    total: 0
    rps: 0
  AUTH:
    total: 0
    rps: 0
  EXECUTE:
    total: 0
    rps: 0
  UPDATE:
    total: 2
    rps: 0
...

tarantool> box.stat().DELETE -- total + requests per second from one table
---
- total: 0
  rps: 0
...

box.stat.net()

box.stat.net()

Shows network activity: the number of bytes sent and received, the number of connections, streams, and requests (current, average, and total).

Return:

in the tables that box.stat.net() returns:

  • SENT.rps and RECEIVED.rps – average number of bytes sent/received per second in the last 5 seconds
  • SENT.total and RECEIVED.total – total number of bytes sent/received since the server started
  • CONNECTIONS.current – number of open connections
  • CONNECTIONS.rps – average number of connections opened per second in the last 5 seconds
  • CONNECTIONS.total – total number of connections opened since the server started
  • REQUESTS.current – number of requests in progress, which can be limited by box.cfg.net_msg_max
  • REQUESTS.rps – average number of requests processed per second in the last 5 seconds
  • REQUESTS.total – total number of requests processed since the server started
  • REQUESTS_IN_PROGRESS.current – number of requests being currently processed by the TX thread
  • REQUESTS_IN_PROGRESS.rps – average number of requests processed by the TX thread per second in the last 5 seconds
  • REQUESTS_IN_PROGRESS.total – total number of requests processed by the TX thread since the server started
  • STREAMS.current – number of active streams
  • STREAMS.rps – average number of streams opened per second in the last 5 seconds
  • STREAMS.total – total number of streams opened since the server started
  • REQUESTS_IN_STREAM_QUEUE.current – number of requests waiting in stream queues
  • REQUESTS_IN_STREAM_QUEUE.rps – average number of requests in stream queues per second in the last 5 seconds
  • REQUESTS_IN_STREAM_QUEUE.total – total number of requests placed in stream queues since the server started

Example:

tarantool> box.stat.net() -- 5 tables
---
- CONNECTIONS:
    current: 1
    rps: 0
    total: 1
  REQUESTS:
    current: 0
    rps: 0
    total: 8
  REQUESTS_IN_PROGRESS:
    current: 0
    rps: 0
    total: 7
  SENT:
    total: 19579
    rps: 0
  REQUESTS_IN_STREAM_QUEUE:
    current: 0
    rps: 0
    total: 0
  STREAMS:
    current: 0
    rps: 0
    total: 0
  RECEIVED:
    total: 197
    rps
...
net.thread()

Shows network activity per network thread: the number of bytes sent and received, the number of connections, streams, and requests (current, average, and total).

When called with an index (box.stat.net.thread[1]), shows network statistics for a single network thread.

Return:Same network activity metrics as box.stat.net() for each network thread

Example:

tarantool> box.stat.net.thread() -- iproto_threads = 2
- - CONNECTIONS:
      current: 0
      rps: 0
      total: 0
    REQUESTS:
      current: 0
      rps: 0
      total: 0
    REQUESTS_IN_PROGRESS:
      current: 0
      rps: 0
      total: 0
    SENT:
      total: 0
      rps: 0
    REQUESTS_IN_STREAM_QUEUE:
      current: 0
      rps: 0
      total: 0
    STREAMS:
      current: 0
      rps: 0
      total: 0
    RECEIVED:
      total: 0
      rps: 0
  - CONNECTIONS:
      current: 1
      rps: 0
      total: 1
    REQUESTS:
      current: 0
      rps: 0
      total: 8
    REQUESTS_IN_PROGRESS:
      current: 0
      rps: 0
      total: 7
    SENT:
      total: 19579
      rps: 0
    REQUESTS_IN_STREAM_QUEUE:
      current: 0
      rps: 0
      total: 0
    STREAMS:
      current: 0
      rps: 0
      total: 0
    RECEIVED:
      total: 197
      rps: 0
...

tarantool> box.stat.net.thread[1] -- first network thread
- - CONNECTIONS:
      current: 1
      rps: 0
      total: 1
    REQUESTS:
      current: 0
      rps: 0
      total: 8
    REQUESTS_IN_PROGRESS:
      current: 0
      rps: 0
      total: 7
    SENT:
      total: 19579
      rps: 0
    REQUESTS_IN_STREAM_QUEUE:
      current: 0
      rps: 0
      total: 0
    STREAMS:
      current: 0
      rps: 0
      total: 0
    RECEIVED:
      total: 197
      rps: 0
...

box.stat.memtx()

box.stat.memtx()

Shows memtx storage engine activity.

box.stat.memtx().data

data shows how much memory (in bytes) is allocated for memtx tuples:

tarantool> box.stat.memtx().data
---
- garbage: 0
  total: 25334
  read_view: 0
...

box.stat.memtx().index

index shows how much memory (in bytes) is allocated for indexing memtx tuples:

tarantool> box.stat.memtx().index
---
- read_view: 0
  total: 1032192
...

box.stat.memtx().tx

tx shows the statistics of the memtx transactional manager, which is responsible for transactions (box.stat.memtx().tx.txn) and multiversion concurrency control (box.stat.memtx().tx.mvcc).

Example

This example illustrates memory statistics for used tuples in a transaction.

The cluster must be started with the database.use_mvcc_engine parameter set to true. This enables MVCC so that box.stat.memtx.tx().mvcc contains non-zero values.

The next step is to create a space with a primary index and to begin a transaction:

box.schema.space.create('test')
box.space.test:create_index('pk')

box.begin()
box.space.test:replace{0, 0}
box.space.test:replace{0, string.rep('a', 100)}
box.space.test:replace{0, 1}
box.space.test:replace{1, 1}
box.space.test:replace{2, 1}

In the transaction above, three tuples are replaced by the 0 key:

MVCC considers all these tuples as used since they belong to the current transaction. Also, MVCC considers tuples {0, 0} and {0, 'aa..aa'} as retained because they don’t belong to any index (unlike {0, 1}) but cannot be deleted yet.

Calling box.stat.memtx.tx() now returns the following result:

tarantool> box.stat.memtx.tx()
---
- txn:
    statements:
      max: 720
      avg: 720
      total: 720
    user:
      max: 0
      avg: 0
      total: 0
    system:
      max: 916
      avg: 916
      total: 916
  mvcc:
    trackers:
      max: 0
      avg: 0
      total: 0
    conflicts:
      max: 0
      avg: 0
      total: 0
    tuples:
      tracking:
        stories:
          count: 0
          total: 0
        retained:
          count: 0
          total: 0
      used:
        stories:
          count: 6
          total: 944
        retained:
          count: 2
          total: 119
      read_view:
        stories:
          count: 0
          total: 0
        retained:
          count: 0
          total: 0
...

Pay attention to highlighted lines – it’s the memory allocated for used tuples.

box.stat.vinyl()

box.stat.vinyl()

Shows vinyl-storage-engine activity, for example box.stat.vinyl().tx has the number of commits and rollbacks.

Example:

tarantool> box.stat.vinyl().tx.commit -- one item of the vinyl table
---
- 1047632
...

box.stat.vinyl().regulator

The vinyl regulator decides when to take or delay actions for disk IO, grouping activity in batches so that it is consistent and efficient. The regulator is invoked by the vinyl scheduler, once per second, and updates related variables whenever it is invoked.

box.stat.vinyl().disk

Since vinyl is an on-disk storage engine (unlike memtx which is an in-memory storage engine), it can handle large databases – but if a database is larger than the amount of memory that is allocated for vinyl, then there will be more disk activity.

box.stat.vinyl().memory

Although the vinyl storage engine is not «in-memory», Tarantool does need to have memory for write buffers and for caches:

Therefore we can say that «L0 is becoming full» when the amount in memory.level0 is close to the maximum, which is regulator.dump_watermark. We can expect that «L0 = 0» immediately after a dump. box.stat.vinyl().memory.page_index and box.stat.vinyl().memory.bloom_filter have the current amount being used for index-related structures. The size is a function of the number and size of keys, plus vinyl_page_size, plus vinyl_bloom_fpr. This is not a count of bloom filter «hits» (the number of reads that could be avoided because the bloom filter predicts their presence in a run file) – that statistic can be found with index_object:stat().

box.stat.vinyl().tx

This is about requests that affect transactional activity («tx» is used here as an abbreviation for «transaction»):

box.stat.vinyl().scheduler

This primarily has counters related to tasks that the scheduler has arranged for dumping or compaction: (most of these items are reset to 0 when the server restarts or when box.stat.reset() occurs):

box.stat.reset()

box.stat.reset()

Resets the statistics of box.stat(), box.stat.net(), box.stat.memtx(), box.stat.vinyl(), and box.space.index.

Вложенный модуль box.tuple

Вложенный модуль box.tuple предоставляет доступ только для чтения к пользовательским данным типа кортеж tuple. С его помощью для отдельного кортежа можно сделать следующее: выборочно искать содержимое поля, получать информацию о размере, проводить итерацию по всем полям и выполнять преобразование в Lua-таблицу.

Ниже приведен перечень всех функций модуля box.tuple.

Имя Использование
box.tuple.new() Создание кортежа
box.tuple.is() Проверка, является ли переданный объект кортежем
#tuple_object Подсчет полей кортежа
box.tuple.bsize() Подсчет байтов в кортеже
tuple_object[field-number] Получение поля кортежа по номеру
tuple_object[field-name] Получение поля кортежа по имени
tuple_object[field-path] Получение полей кортежа или компонентов по пути
tuple_object:find(), tuple_object:findall() Получение номера первого поля, совпадающего с искомым значением
tuple_object.info() Get information about the tuple
tuple_object:next() Получение значения следующего поля из кортежа
tuple_object:pairs(), tuple_object:ipairs() Подготовка к итерации
tuple_object:totable() Получение полей кортежа в виде таблицы
tuple_object:tomap() Получение полей кортежа в виде таблицы, а также пар ключ-значение
tuple_object:transform() Удаление (и замена) полей кортежа
tuple_object:unpack() Получение полей кортежа
tuple_object:update() Обновление кортежа
tuple_object:upsert() Обновление кортежа, игнорируя ошибки

Как преобразовать кортежи в Lua-таблицы и обратно

Представленная ниже функция проиллюстрирует, как можно преобразовать кортежи в Lua-таблицы и списки скаляров и обратно:

tuple = box.tuple.new({scalar1, scalar2, ... scalar_n}) -- скаляры в кортеж
lua_table = {tuple:unpack()}                            -- кортеж в Lua-таблицу
lua_table = tuple:totable()                             -- кортеж в Lua-таблицу
scalar1, scalar2, ... scalar_n = tuple:unpack()         -- кортеж в скаляры
tuple = box.tuple.new(lua_table)                        -- Lua-таблицу в кортеж

Затем она найдет поле, которое содержит значение „b“, удалит это поле из кортежа и отобразит количество байтов, оставшихся в кортеже. Данная функция использует следующие функции box.tuple Tarantool: new(), unpack(), find(), transform(), bsize().

function example()
  local tuple1, tuple2, lua_table_1, scalar1, scalar2, scalar3, field_number
  local luatable1 = {}
  tuple1 = box.tuple.new({'a', 'b', 'c'})
  luatable1 = tuple1:totable()
  scalar1, scalar2, scalar3 = tuple1:unpack()
  tuple2 = box.tuple.new(luatable1[1],luatable1[2],luatable1[3])
  field_number = tuple2:find('b')
  tuple2 = tuple2:transform(field_number, 1)
  return 'tuple2 = ' , tuple2 , ' # of bytes = ' , tuple2:bsize()
end

… А вот что происходит, когда вызывается функция:

tarantool> example()
---
- tuple2 =
- ['a', 'c']
- ' # of bytes = '
- 5
...

box.tuple.new()

box.tuple.new(value)

Создание нового кортежа либо из скаляра, либо из Lua-таблицы. Возможен и вариант получения новых кортежей из запросов select или insert. или replace, или update Tarantool, которые можно рассматривать в качестве операторов, косвенно выполняющих операцию создания new().

Параметры:
  • value (lua-value) – значение, которое станет содержимым кортежа.
возвращает:

новый кортеж
тип возвращаемого значения:
 

кортеж

В следующем примере x будет представлять собой новый объект таблицы, который содержит один кортеж, а t будет представлять собой объект кортежа. Если ввести команду t, будет получен весь кортеж t.

Пример:

tarantool> x = box.space.tester:insert{
         >   33,
         >   tonumber('1'),
         >   tonumber64('2')
         > }:totable()
---
...
tarantool> t = box.tuple.new{'abc', 'def', 'ghi', 'abc'}
---
...
tarantool> t
---
- ['abc', 'def', 'ghi', 'abc']
...

box.tuple.is()

box.tuple.is(object)

Since versions 2.2.3, 2.3.2, and 2.4.1. A function to check whether a given object is a tuple cdata object. Never raises nor returns an error.

возвращает:true или false
возвращаемое значение:
 boolean (логический)

#tuple_object

object tuple_object
#<tuple_object>

Оператор # на языке Lua означает «вернуть количество компонентов». Таким образом, если t представляет собой кортеж, то #t вернет количество полей.

тип возвращаемого значения:
 число

В следующем примере создается кортеж под названием t, а затем возвращается количество полей в кортеже t.

tarantool> t = box.tuple.new{'Fld#1', 'Fld#2', 'Fld#3', 'Fld#4'}
---
...
tarantool> #t
---
- 4
...

box.tuple.bsize()

object tuple_object
tuple_object:bsize()

Если t – это экземпляр кортежа, то t:bsize() вернет количество байтов в кортеже. Как для движка базы данных memtx, так и для движка vinyl максимальное количество, используемое по умолчанию, составляет один мегабайт (memtx_max_tuple_size или vinyl_max_tuple_size). В каждом поле есть один или более байтов «длины», которые предваряют само содержимое поля, поэтому bsize() вернет значение, которое незначительно больше, чем сумма длин всего содержимого.

Значение не содержит размер кортежа «struct tuple» (чтобы узнать текущий размер данной структуры, посмотрите файл tuple.h в исходном коде Tarantool).

возвращает:количество байтов
тип возвращаемого значения:
 число

В следующем примере создается кортеж с именем t, в котором три поля, и для каждого поля один байт занимает хранение длины, и три байта занимает хранение содержимого, кроме того, один бит используется на ресурсы, поэтому bsize() вернет 3*(1+3)+1. Такой же размер строки вернула бы функция msgpack.encode({„aaa“,“bbb“,“ccc“}).

tarantool> t = box.tuple.new{'aaa', 'bbb', 'ccc'}
---
...
tarantool> t:bsize()
---
- 13
...

tuple_object[field-number]

object tuple_object
<tuple_object>[field-number]

Если t – это экземпляр кортежа, то t[номер-поля] вернет поле под номером номер-поля в кортеже. Первое поле – это t[1].

возвращает:значение поля.
тип возвращаемого значения:
 Lua-значение

В следующем примере создается кортеж под названием t, а затем возвращается второе поле в кортеже t.

tarantool> t = box.tuple.new{'Fld#1', 'Fld#2', 'Fld#3', 'Fld#4'}
---
...
tarantool> t[2]
---
- Fld#2
...

tuple_object[field-name]

object tuple_object
<tuple_object>[field-name]

Если t – это экземпляр кортежа, то t['field-name'] вернет поле под названием field-name в кортеже. У полей есть имена, если кортеж был получен из спейса с определенным форматом. t[lua-variable-name] сделает то же самое, если lua-variable-name содержит 'field-name'.

Есть вариация, которую Lua manual называет «синтаксический сахар»: можно использовать t.field-name вместо t['field-name'].

возвращает:значение поля
тип возвращаемого значения:
 Lua-значение

В следующем примере кортеж под названием t возвращается после операции замены, а затем возвращается второе поле с именем „field2“ в кортеже t.

tarantool> format = {}
---
...
tarantool> format[1] = {name = 'field1', type = 'unsigned'}
---
...
tarantool> format[2] = {name = 'field2', type = 'string'}
---
...
tarantool> s = box.schema.space.create('test', {format = format})
---
...
tarantool> pk = s:create_index('pk')
---
...
tarantool> t = s:replace{1, 'Я'}
---
...
tarantool> t['field2']
---
- Я
...

tuple_object[field-path]

object tuple_object
<tuple_object>[field-path]

Если t – это экземпляр кортежа, то t['path'] вернет поле или ряд полей, которые находятся в path. Параметр path должен представлять собой правильную JSON-спецификацию. path может содержать имена полей, если кортеж был получен из спейса с заданным форматом.

Во избежание неоднозначности Tarantool сначала пытается интерпретировать запрос как tuple_object[field-number] или tuple_object[field-name]. И только в том случае, если это не удается, Tarantool пытается интерпретировать запрос как tuple_object[field-path].

Путь path должен представлять собой правильную JSON-спецификацию, но в начале может стоять „.“. Символ „.“ означает, что путь выступает в качестве суффикса для кортежа.

При указании пути Tarantool воспользуется им для поиска по телу кортежа и вернет только тот компонент кортежа, который действительно необходим.

In the following example, a tuple named t is returned from replace and then only the relevant part (in this case, matching a name) of a relevant field is returned. Namely: the second field, its third item, the value following „key=“.

tarantool> format = {}
---
...
tarantool> format[1] = {name = 'field1', type = 'unsigned'}
---
...
tarantool> format[2] = {name = 'field2', type = 'array'}
---
...
tarantool> s = box.schema.space.create('test', {format = format})
---
...
tarantool> pk = s:create_index('pk')
---
...
tarantool> field2_value = {1, "ABC", {key="Hello", value="world"}}
---
...
tarantool> t = s:replace{1, field2_value}
---
...
tarantool> t["[2][3]['key']"]
---
- Hello
...

tuple_object:find(), tuple_object:findall()

object tuple_object
tuple_object:find([field-number, ]search-value)
tuple_object:findall([field-number, ]search-value)

Если t – это экземпляр кортежа, то t:find(search-value) вернет номер первого поля в t, которое совпадает с искомым значением, а t:findall(search-value [, search-value ...]) вернет номера всех колей в t, которые совпадают с искомым значением. Можно дополнительно добавить числовой аргумент field-number перед search-value, чтобы задать условие “начинать поиск с номера поля field-number.”

возвращает:номер поля в кортеже.
тип возвращаемого значения:
 число

В следующем примере создается кортеж с именем t, а затем: возвращается номер первого поля в t, которое совпадает с „a“, затем возвращаются номера всех полей в t, которые совпадают с „a“, затем возвращаются номера всех полей в t, которые совпадают с „a“, и находятся на втором месте или далее.

tarantool> t = box.tuple.new{'a', 'b', 'c', 'a'}
---
...
tarantool> t:find('a')
---
- 1
...
tarantool> t:findall('a')
---
- 1
- 4
...
tarantool> t:findall(2, 'a')
---
- 4
...

tuple_object.info()

object tuple_object
tuple_object:info()

Get information about the tuple memory usage.

Returns a table with the following fields:

  • data_size – size of MessagePack data in the tuple. This number equals to number returned by box.tuple.bsize().

  • header_size - size of the internal tuple header.

  • field_map_size – size of the field map. Field map is used to speed up access to indexed fields of the tuple.

  • waste_size – amount of excess memory wasted due to internal fragmentation in the slab allocator.

    Примечание

    waste_size is provided for reference only and can be inaccurate. Avoid using it for memory usage calculations.

  • arena - type of the arena where the tuple is allocated. Possible values are: memtx, malloc, runtime.

Return:tuple memory usage statistics
Rtype:table

Example

tarantool> box.space.tester:get('222200000'):info()
---
- data_size: 55
  waste_size: 95
  arena: memtx
  field_map_size: 4
  header_size: 6
...

tuple_object:next()

object tuple_object
tuple_object:next(tuple[, pos])

Аналог функции Lua next(), но для кортежа. При вызове без аргументов, tuple:next() возвращает первое поле из кортежа. В противном случае возвращается поле рядом с указанной позицией.

Однако tuple:next() не очень эффективен, и лучше использовать tuple:pairs()/ipairs().

возвращает:номер и значение поля
тип возвращаемого значения:
 число (number) и тип поля 
tarantool> tuple = box.tuple.new({5, 4, 3, 2, 0})
---
...

tarantool> tuple:next()
---
- 1
- 5
...

tarantool> tuple:next(1)
---
- 2
- 4
...

tarantool> ctx, field = tuple:next()
---
...

tarantool> while field do
         > print(field)
         > ctx, field = tuple:next(ctx)
         > end
5
4
3
2
0
---
...

tuple_object:pairs(), tuple_object:ipairs()

object tuple_object
tuple_object:pairs()
tuple_object:ipairs()

В языке Lua метод lua-table-value:pairs() возвращает: функция, значение-Lua-таблицы, nil. В Tarantool метод расширен так, что tuple-value:pairs() возвращает: функция, значение-кортежа, nil, – что используется для Lua-итераторов, поскольку они обходят компоненты значения до тех пор, пока не достигнут маркера.

tuple_object:ipairs() – это то же самое, что и pairs(), потому что поля кортежей всегда явялются натуральными числами.

возвращает:функция, значение кортежа, nil
тип возвращаемого значения:
 функция, Lua-значение, nil

В следующем примере создается кортеж под названием t, а затем все его поля выбираются с помощью Lua-цикла for.

tarantool> t = box.tuple.new{'Fld#1', 'Fld#2', 'Fld#3', 'Fld#4', 'Fld#5'}
---
...
tarantool> tmp = ''
---
...
tarantool> for k, v in t:pairs() do
         >   tmp = tmp .. v
         > end
---
...
tarantool> tmp
---
- Fld#1Fld#2Fld#3Fld#4Fld#5
...

tuple_object:totable()

object tuple_object
tuple_object:totable([start-field-number[, end-field-number]])

Если t – это экземпляр кортежа, то t:totable() вернет все поля, t:totable(1) вернет все поля, начиная с поля №1, t:totable(1,5) вернет все поля между полем №1 и полем №5.

Рекомендуется использовать t:totable(), а не t:unpack().

возвращает:поле или поля из кортежа
тип возвращаемого значения:
 Lua-таблица

В следующем примере создается кортеж под названием t, а затем делается выборка всех полей, возвращается результат.

tarantool> t = box.tuple.new{'Fld#1', 'Fld#2', 'Fld#3', 'Fld#4', 'Fld#5'}
---
...
tarantool> t:totable()
---
- ['Fld#1', 'Fld#2', 'Fld#3', 'Fld#4', 'Fld#5']
...

tuple_object:tomap()

object tuple_object
tuple_object:tomap([options])

В Lua-таблице могут быть индексированные значения, которые также называются пары ключ-значение. Например, здесь:

a = {}; a['field1'] = 10; a['field2'] = 20

a – это таблица с «field1: 10» и «field2: 20».

Функция tuple_object:totable() вернет только таблицу со значениями. А функция tuple_object:tomap() вернет таблицу не только со значениями, но и с парами ключ-значение.

Это сработает только в том случае, если кортеж приходит из спейса, который был форматирован посредством оператора формата.

Параметры:
  • options (table) – единственный доступный параметр – names_only. Если names_only принимает значение false или не указан (по умолчанию), то все поля появятся дважды: сначала с числовыми заголовками, а затем с именными заголовками. Если же names_only = true, то все поля будут выведены один раз с именными заголовками.
возвращает:

пары номер-поля:значение и пары ключ:значение из кортежа
тип возвращаемого значения:
 

Lua-таблица

В следующем примере возвращается кортеж с именем t1 из спейса после форматирования, затем таблицы с именами t1map и t1map2 создаются из t1.

format = {{'field1', 'unsigned'}, {'field2', 'unsigned'}}
s = box.schema.space.create('test', {format = format})
s:create_index('pk',{parts={1,'unsigned',2,'unsigned'}})
t1 = s:insert{10, 20}
t1map = t1:tomap()
t1map_names_only = t1:tomap({names_only=true})

t1map будет содержать «1: 10», «2: 20», «field1: 10», «field2: 20».

t1map_names_only будет содержать «field1: 10» и «field2: 20».

tuple_object:transform()

object tuple_object
tuple_object:transform(start-field-number, fields-to-remove[, field-value, ...])

Если t – это экземпляр кортежа, то t:transform(start-field-number,fields-to-remove) вернет кортеж, где начиная с поля start-field-number, удаляется количество полей (fields-to-remove). Дополнительно можно добавить аргументы после fields-to-remove, чтобы указать новые значения на замену удаленных.

Если первоначальный кортеж приходит из спейса, который был форматирован посредством оператора формата, форматирование возвращаемого кортежа не сохранится.

Параметры:
  • start-field-number (integer) – начиная с 1, может быть отрицательным
  • fields-to-remove (integer) –
  • field-value(s) (lua-value) –
возвращает:

tuple
тип возвращаемого значения:
 

tuple

В следующем примере создается кортеж под названием t, а затем начиная со второго поля, удаляются два поля, а одно новое поле добавляется, затем возвращается результат.

tarantool> t = box.tuple.new{'Fld#1', 'Fld#2', 'Fld#3', 'Fld#4', 'Fld#5'}
---
...
tarantool> t:transform(2, 2, 'x')
---
- ['Fld#1', 'x', 'Fld#4', 'Fld#5']
...

tuple_object:unpack()

object tuple_object
tuple_object:unpack([start-field-number[, end-field-number]])

Если t – это экземпляр кортежа, то t:unpack() вернет все поля, t:unpack(1) вернет все поля, начиная с поля №1, t:unpack(1,5) вернет все поля между полем №1 и полем №5.

возвращает:поле или поля из кортежа.
тип возвращаемого значения:
 Lua-значение(я)

В следующем примере создается кортеж под названием t, а затем делается выборка всех полей, возвращается результат.

tarantool> t = box.tuple.new{'Fld#1', 'Fld#2', 'Fld#3', 'Fld#4', 'Fld#5'}
---
...
tarantool> t:unpack()
---
- Fld#1
- Fld#2
- Fld#3
- Fld#4
- Fld#5
...

tuple_object:update()

object tuple_object
tuple_object:update({{operator, field_no, value}, ...})

Обновление кортежа.

Эта функция обновляет кортеж, который находится не в спейсе. Ср. функцию box.space.space-name:update(key, {{format, field_no, value}, ...}), которая обновляет кортеж в спейсе.

Более подробную информацию см. в описании operator, field_no и value в разделе box.space.space-name:update{key, format, {field_number, value}…).

Если первоначальный кортеж приходит из спейса, который был форматирован посредством оператора формата, форматирование возвращаемого кортежа сохранится.

Параметры:
  • operator (string) – тип операции, представленный строкой (например, „=“ означает „присвоить новое значение“)
  • field_no (number) – к какому полю применяется операция. Номер поля может быть отрицательным, что означает, что позиция рассчитывается с конца кортежа. (#кортеж + отрицательный номер поля + 1)
  • value (lua_value) – какое значение применяется
возвращает:

новый кортеж
тип возвращаемого значения:
 

кортеж

В следующем примере создается кортеж под названием t, а затем второе поле обновляется до равного „B“.

tarantool> t = box.tuple.new{'Fld#1', 'Fld#2', 'Fld#3', 'Fld#4', 'Fld#5'}
---
...
tarantool> t:update({{'=', 2, 'B'}})
---
- ['Fld#1', 'B', 'Fld#3', 'Fld#4', 'Fld#5']
...

Начиная с версии Tarantool 2.3 кортеж можно обновить с помощью JSON-путей.

tuple_object:upsert()

object tuple_object
tuple_object:upsert({{operator, field_no, value}, ...})

То же самое, что и tuple_object:update(), но игнорирует ошибки. В случае ошибки кортеж остаётся нетронутым, но выводится сообщение об ошибке. Игнорируются только клиентские ошибки, такие как «плохой тип поля» или «неправильный индекс/имя» поля. Системные ошибки, такие как OOM, не игнорируются и поднимаются так же, как и при обычном update(). Обратите внимание, что игнорируются только некорректные операции. Все корректные операции применяются.

Параметры:
  • operator (string) – тип операции, представленный строкой (например, „=“ означает „присвоить новое значение“)
  • field_no (number) – к какому полю применяется операция. Номер поля может быть отрицательным, что означает, что позиция рассчитывается с конца кортежа. (#кортеж + отрицательный номер поля + 1)
  • value (lua_value) – значение, которое применяется
возвращает:

новый кортеж
тип возвращаемого значения:
 

tuple

В следующем примере одна операция применяется, а другая – нет.

tarantool> t = box.tuple.new({1, 2, 3})
tarantool> t2 = t:upsert({{'=', 5, 100}})
UPSERT operation failed:
ER_NO_SUCH_FIELD_NO: Field 5 was not found in the tuple
---
...

tarantool> t
---
- [1, 2, 3]
...

tarantool> t2
---
- [1, 2, 3]
...

tarantool> t2 = t:upsert({{'=', 5, 100}, {'+', 1, 3}})
UPSERT operation failed:
ER_NO_SUCH_FIELD_NO: Field 5 was not found in the tuple
---
...

tarantool> t
---
- [1, 2, 3]
...

tarantool> t2
---
- [4, 2, 3]
...

Управление экземплярами

For general information and examples, see section Transactions.

Соблюдайте следующие правила в работе с транзакциями:

Правило #1

Запросы в транзакции должны отправляться на сервер в виде единого блока. Недостаточно просто размещать их между началом транзакции и коммитом или откатом. Чтобы убедиться, что они отправляются в виде единого блока: поместите их в функцию, поместите их на одну строку или используйте символы-разделители, чтобы многостроковые запросы обрабатывались совместно.

Правило #2

Все операции с базой данных в рамках транзакции должны работать с одним движком баз данных. Небезопасно в рамках одной транзакции получать доступ к наборам кортежей, которые определяются по {engine='vinyl'}, а также к наборам кортежей, которые определяются по {engine='memtx'}.

Правило #3

Requests which cause changes to the data definition – create, alter, drop, truncate – are only allowed with Tarantool version 2.1 or later. Data-definition requests which change an index or change a format, such as space_object:create_index() and space_object:format(), are not allowed inside transactions except as the first request after box.begin().

Ниже приведен перечень всех функций для управления транзакциями.

Имя Использование
box.begin() Начало транзакции
box.commit() Окончание транзакции и сохранение всех изменений
box.rollback() Окончание транзакции и отмена всех изменений
box.savepoint() Получение дескриптора точки сохранения
box.rollback_to_savepoint() Запрещение окончания транзакции и отмена всех изменений, сделанных после точки сохранения
box.atomic() Выполнение функции как транзакции
box.on_commit() Определение триггера, активируемого по box.commit
box.on_rollback() Определение триггера, активируемого по box.rollback
box.is_in_txn() Обозначение наличия активной транзакции

box.begin()

box.begin([opts])

Начало транзакции. Отключение неявной передачи управления до окончания транзакции. Сигнал о записи в журнал упреждающей записи будет задержан до окончания транзакции. Фактически файбер, который выполняет функцию box.begin(), начинает «активную транзакцию со множеством запросов» с блокировкой всех остальных файберов.

Параметры:
  • opts (table) –

    (optional) transaction options:

Возможные ошибки:

  • ошибка, если такая операция не допускается, потому что уже есть активная транзакция.
  • ошибка, если по какой-либо причине нельзя выделить память.
  • error and abort the transaction if the timeout is exceeded.

Example

-- Insert test data --
box.space.bands:insert { 1, 'Roxette', 1986 }
box.space.bands:insert { 2, 'Scorpions', 1965 }
box.space.bands:insert { 3, 'Ace of Base', 1987 }

-- Begin and commit the transaction explicitly --
box.begin()
box.space.bands:insert { 4, 'The Beatles', 1960 }
box.space.bands:replace { 1, 'Pink Floyd', 1965 }
box.commit()

-- Begin the transaction with the specified isolation level --
box.begin({ txn_isolation = 'read-committed' })
box.space.bands:insert { 5, 'The Rolling Stones', 1962 }
box.space.bands:replace { 1, 'The Doors', 1965 }
box.commit()

box.commit()

box.commit()

Окончание транзакции и применение результатов всех операций по изменению данных.

Возможные ошибки:

  • ошибка и прерывание транзакции в случае конфликта.
  • ошибка, если операция не может выполнить запись на диск.
  • ошибка, если по какой-либо причине нельзя выделить память.

Example

-- Insert test data --
box.space.bands:insert { 1, 'Roxette', 1986 }
box.space.bands:insert { 2, 'Scorpions', 1965 }
box.space.bands:insert { 3, 'Ace of Base', 1987 }

-- Begin and commit the transaction explicitly --
box.begin()
box.space.bands:insert { 4, 'The Beatles', 1960 }
box.space.bands:replace { 1, 'Pink Floyd', 1965 }
box.commit()

-- Begin the transaction with the specified isolation level --
box.begin({ txn_isolation = 'read-committed' })
box.space.bands:insert { 5, 'The Rolling Stones', 1962 }
box.space.bands:replace { 1, 'The Doors', 1965 }
box.commit()

box.rollback()

box.rollback()

Окончание транзакции, но отмена результатов всех операций по изменению данных. Явный вызов функций не из модуля box.space, которые всегда передают управление, например fiber.sleep() или fiber.yield(), приведет к тому же результату.

Example

-- Insert test data --
box.space.bands:insert { 1, 'Roxette', 1986 }
box.space.bands:insert { 2, 'Scorpions', 1965 }
box.space.bands:insert { 3, 'Ace of Base', 1987 }

-- Rollback the transaction --
box.begin()
box.space.bands:insert { 4, 'The Beatles', 1960 }
box.space.bands:replace { 1, 'Pink Floyd', 1965 }
box.rollback()

box.savepoint()

box.savepoint()

Выдача дескриптора точки сохранения (тип = таблица), который может затем использоваться в box.rollback_to_savepoint(savepoint). Точки сохранения могут быть созданы, пока активна транзакция, и удаляются после окончания транзакции.

возвращает:таблица точки сохранения
тип возвращаемого значения:
 Lua-объект
возвращает:ошибка, если точку сохранения нельзя указать в отсутствие активной транзакции.

Возможные ошибки: ошибка, если по какой-либо причине нельзя выделить память.

Example

-- Insert test data --
box.space.bands:insert { 1, 'Roxette', 1986 }
box.space.bands:insert { 2, 'Scorpions', 1965 }
box.space.bands:insert { 3, 'Ace of Base', 1987 }

-- Rollback the transaction to a savepoint --
box.begin()
box.space.bands:insert { 4, 'The Beatles', 1960 }
save1 = box.savepoint()
box.space.bands:replace { 1, 'Pink Floyd', 1965 }
box.rollback_to_savepoint(save1)
box.commit()

box.rollback_to_savepoint()

box.rollback_to_savepoint(savepoint)

Запрещение окончания транзакции, но отмена всех изменений и операций box.savepoint(), сделанных после точки сохранения.

возвращает:ошибка, если точка сохранения не может быть установлена при отсутствии активной транзакции.

Возможные ошибки: ошибка, если отсутствует точка сохранения.

Example

-- Insert test data --
box.space.bands:insert { 1, 'Roxette', 1986 }
box.space.bands:insert { 2, 'Scorpions', 1965 }
box.space.bands:insert { 3, 'Ace of Base', 1987 }

-- Rollback the transaction to a savepoint --
box.begin()
box.space.bands:insert { 4, 'The Beatles', 1960 }
save1 = box.savepoint()
box.space.bands:replace { 1, 'Pink Floyd', 1965 }
box.rollback_to_savepoint(save1)
box.commit()

box.atomic()

box.atomic([opts, ]tx-function[, function-arguments])

Выполнение функции так, как будто функция начинается с явного вызова box.begin() и заканчивается неявным вызовом box.commit() после успешного выполнения или же заканчивается неявным вызовом box.rollback() в случае ошибки.

Параметры:
  • opts (table) –

    (optional) transaction options:

  • tx-function (string) – the function name
  • function-arguments – (optional) arguments passed to the function
возвращает:

the result of the function passed to atomic() as an argument

Возможные ошибки:

  • ошибка и прерывание транзакции в случае конфликта.
  • error and abort the transaction if the timeout is exceeded.
  • ошибка, если операция не может выполнить запись на диск.
  • ошибка, если по какой-либо причине нельзя выделить память.

Example

-- Create an index with the specified sequence --
box.schema.sequence.create('id_sequence', { min = 1 })
box.space.bands:create_index('primary', { parts = { 'id' }, sequence = 'id_sequence' })

-- Insert test data --
box.space.bands:insert { 1, 'Roxette', 1986 }
box.space.bands:insert { 2, 'Scorpions', 1965 }
box.space.bands:insert { 3, 'Ace of Base', 1987 }

-- Define a function --
local function insert_band(band_name, year)
    box.space.bands:insert { nil, band_name, year }
end

-- Begin and commit the transaction implicitly --
box.atomic(insert_band, 'The Beatles', 1960)

-- Begin the transaction with the specified isolation level --
box.atomic({ txn_isolation = 'read-committed' },
        insert_band, 'The Rolling Stones', 1962)

box.on_commit()

box.on_commit(trigger-function[, old-trigger-function])

Определения триггера, выполняемого в случае окончания транзакции в связи с box.commit().

Функция с триггером может принимать параметр с итератором, как описано в примере к данному разделу.

Функция с триггером не должна получать доступ к любым спейсам базы данных.

Если триггер не сработает и выдаст ошибку, результат будет неблагоприятным, чего следует избегать – используйте Lua-механизм pcall() вокруг кода, который может не сработать.

box.on_commit() следует вызывать в пределах транзакции, и триггер прекращает существование по окончании транзакции.

Параметры:
  • trigger-function (function) – функция, в которой будет триггер
  • old-trigger-function (function) – существующая функция с триггером, которую заменит новая
возвращает:

nil или указатель функции

Если указаны параметры (nil, old-trigger-function), старый триггер будет удален.

Подробная информация о характеристиках триггера находится в разделе Триггеры.

Example 1

-- Insert test data --
box.space.bands:insert { 1, 'Roxette', 1986 }
box.space.bands:insert { 2, 'Scorpions', 1965 }
box.space.bands:insert { 3, 'Ace of Base', 1987 }

-- Define a function called on commit --
function print_commit_result()
    print('Commit happened')
end

-- Commit the transaction --
box.begin()
box.space.bands:insert { 4, 'The Beatles', 1960 }
box.on_commit(print_commit_result)
box.commit()

Example 2

The function parameter can be an iterator. The iterator goes through the effects of every request that changed a space during the transaction.

The iterator has:

  • an ordinal request number
  • the old value of the tuple before the request (nil for an insert request)
  • the new value of the tuple after the request (nil for a delete request)
  • the ID of the space

The example below displays the effects of two replace requests:

-- Insert test data --
box.space.bands:insert { 1, 'Roxette', 1986 }
box.space.bands:insert { 2, 'Scorpions', 1965 }
box.space.bands:insert { 3, 'Ace of Base', 1987 }

-- Define a function called on commit --
function print_replace_details(iterator)
    for request_number, old_tuple, new_tuple, space_id in iterator() do
        print('request_number: ' .. tostring(request_number))
        print('old_tuple: ' .. tostring(old_tuple))
        print('new_tuple: ' .. tostring(new_tuple))
        print('space_id: ' .. tostring(space_id))
    end
end

-- Commit the transaction --
box.begin()
box.space.bands:replace { 1, 'The Beatles', 1960 }
box.space.bands:replace { 2, 'The Rolling Stones', 1965 }
box.on_commit(print_replace_details)
box.commit()

The output might look like this:

request_number: 1
old_tuple: [1, 'Roxette', 1986]
new_tuple: [1, 'The Beatles', 1960]
space_id: 512
request_number: 2
old_tuple: [2, 'Scorpions', 1965]
new_tuple: [2, 'The Rolling Stones', 1965]
space_id: 512

box.on_rollback()

box.on_rollback(trigger-function[, old-trigger-function])

Определение триггера, выполняемого по окончании транзакции в связи с box.rollback().

Используются точно такие же параметры и предупреждения, как в box.on_commit().

box.is_in_txn()

box.is_in_txn()

В процессе транзакции (например, пользователь вызвал box.begin() и еще не вызвал ни box.commit, ни box.rollback()) возвращается true. В остальных случаях возвращается false.

Functions for SQL

The box module contains some functions related to SQL:

Some SQL statements are illustrated in the SQL tutorial.

Below is a list of all SQL functions and members.

Имя Назначение
box.execute() Make Lua functions callable from SQL statements. See Calling Lua routines from SQL in the SQL Plus Lua section
box.prepare() Make SQL statements callable from Lua functions. See the SQL user guide
object prepared_table Methods for prepared SQL statement

box.execute()

box.execute(sql-statement[, extra-parameters])

Execute the SQL statement contained in the sql-statement parameter.

Параметры:
возвращает:

depends on statement

There are two ways to pass extra parameters to box.execute():

  • The first way, which is the preferred way, is to put placeholders in the string, and pass a second argument, an extra-parameters table. A placeholder is either a question mark «?», or a colon «:» followed by a name. An extra parameter is any Lua expression.

    If placeholders are question marks, then they are replaced by extra-parameters values in corresponding positions. That is, the first ? is replaced by the first extra parameter, the second ? is replaced by the second extra parameter, and so on.

    If placeholders are :names, then they are replaced by extra-parameters values with corresponding names.

    For example, this request that contains literal values 1 and 'x':

    box.execute([[INSERT INTO tt VALUES (1, 'x');]]);

    … is the same as the request below containing two question-mark placeholders (? and ?) and a two-element extra-parameters table:

    x = {1,'x'}
box.execute([[INSERT INTO tt VALUES (?, ?);]], x);

    … and is the same as this request containing two :name placeholders (:a and :b) and a two-element extra-parameters table with elements named «a» and «b»:

    box.execute([[INSERT INTO tt VALUES (:a, :b);]], {{[':a']=1},{[':b']='x'}})

  • The second way is to concatenate strings. For example, the Lua script below inserts 10 rows with different primary-key values into table t:

    for i=1,10,1 do
    box.execute("insert into t values (" .. i .. ")")
end

    When creating SQL statements based on user input, application developers should beware of SQL injection.

Since box.execute() is an invocation of a Lua function, it either causes an error message or returns a value.

For some statements the returned value contains a field named rowcount, for example:

tarantool> box.execute([[CREATE TABLE table1 (column1 INT PRIMARY key, column2 VARCHAR(10));]])
---
- rowcount: 1
...
tarantool> box.execute([[INSERT INTO table1 VALUES (55,'Hello SQL world!');]])
---
- rowcount: 1
...

For statements that cause generation of values for PRIMARY KEY AUTOINCREMENT columns, there is a field named autoincrement_id.

For SELECT or PRAGMA statements, the returned value is a result set, containing a field named metadata (a table with column names and Tarantool/NoSQL type names) and a field named rows (a table with the contents of each row).

For example, for a statement SELECT "x" FROM t WHERE "x"=5; where "x" is an INTEGER column and there is one row, a display on the Tarantool client might look like this:

tarantool> box.execute([[SELECT "x" FROM t WHERE "x"=5;]])
---
- metadata:
  - name: x
    type: integer
  rows:
  - [5]
...

For a look at raw format of SELECT results, see Binary protocol – responses for SQL.

The order of components within a map is not guaranteed.

If sql_full_metadata in the _session_settings system table is TRUE, then result set metadata may include these things in addition to name and type:

  • collation (present only if COLLATE clause is specified for a STRING) = «Collation».
  • is_nullable (present only if the select list specified a base table column and nothing else) = false if column was defined as NOT NULL, otherwise true. If this is not present, that implies that nullability is unknown.
  • is_autoincrement (present only if the select list specified a base table column and nothing else) = true if column was defined as PRIMARY KEY AUTOINCREMENT, otherwise false.
  • span (always present) = the original expression in a select list, which often is the same as name if the select list specifies a column name and nothing else, but otherwise differs, for example, after SELECT x+55 AS x FROM t; the name is X and the span is x+55. If span and name are the same then the content is MP_NIL.

Alternative: if you are using the Tarantool server as a client, you can switch languages as follows:

\set language sql
\set delimiter ;

Afterwards, you can enter any SQL statement directly without needing box.execute().

There is also an execute() function available in module net.box. For example, you can execute conn:execute(sql-statement]) after conn = net_box.connect(url-string).

box.prepare()

box.prepare(sql-statement)

Prepare the SQL statement contained in the sql-statement parameter. The syntax and requirements for box.prepare are the same as for box.execute().

Параметры:
возвращает:

prepared_table, with id and methods and metadata
тип возвращаемого значения:
 

таблица

box.prepare compiles an SQL statement into byte code and saves the byte code in a cache. Since compiling takes a significant amount of time, preparing a statement will enhance performance if the statement is executed many times.

If box.prepare succeeds, prepared_table contains:

  • stmt_id: integer – an identifier generated by a hash of the statement string
  • execute: function
  • params: map [name : string, type : string] – parameter descriptions
  • unprepare: function
  • metadata: map [name : string, type : string] (This is present only for SELECT or PRAGMA statements and has the same contents as the result set metadata for box.execute)
  • param_count: integer – number of parameters

This can be used by prepared_table:execute() and by prepared_table:unprepare().

The prepared statement cache (which is also called the prepared statement holder) is «shared», that is, there is one cache for all sessions. However, session X cannot execute a statement prepared by session Y.
For monitoring the cache, see box.info().sql.
For changing the cache size, use sql.cache_size.

Prepared statements will «expire» (become invalid) if any database object is dropped or created or altered – even if the object is not mentioned in the SQL statement, even if the create or drop or alter is rolled back, even if the create or drop or alter is done in a different session.

object prepared_table

object prepared_table
prepared_table:execute([extra-parameters])

Execute a statement that has been prepared with box.prepare().

Parameter prepared_table should be the result from box.prepare().

Parameter extra-parameters should be an optional table to match placeholders or named parameters in the statement.

There are two ways to execute: with the method or with the statement id. That is, prepared_table:execute() and box.execute(prepared_table.stmt_id) do the same thing.

Example: here is a test. This function inserts a million rows in a table using a prepared INSERT statement.

function f()
  local p, start_time
  box.execute([[DROP TABLE IF EXISTS t;]])
  box.execute([[CREATE TABLE t (s1 INTEGER PRIMARY KEY);]])
  start_time = os.time()
  p = box.prepare([[INSERT INTO t VALUES (?);]])
  for i=1,1000000 do p:execute({i}) end
  p:unprepare()
  end_time = os.time()
  box.execute([[COMMIT;]])
  print(end_time - start_time) -- elapsed time
end
f()

Take note of the elapsed time. Now change the line with the loop to:
for i=1,1000000 do box.execute([[INSERT INTO t VALUES (?);]], {i}) end
Run the function again, and take note of the elapsed time again. The function which executes the prepared statement will be about 15% faster, though of course this will vary depending on Tarantool version and environment.

prepared_table:unprepare()

Undo the result of an earlier box.prepare() request. This is equivalent to standard-SQL DEALLOCATE PREPARE.

Parameter prepared_table should be the result from box.prepare().

There are two ways to unprepare: with the method or with the statement id. That is, prepared_table:unprepare() and box.unprepare(prepared_table.stmt_id) do the same thing.

Tarantool strongly recommends using unprepare as soon as the immediate objective (executing a prepared statement multiple times) is done, or whenever a prepared statement expires. There is no automatic eviction policy, although automatic unprepare will happen when the session disconnects (the session’s prepared statements will be removed from the prepared-statement cache).

Event watchers

Since 2.10.0.

The box module contains some features related to event subscriptions, also known as watchers. The subscriptions are used to inform the client about server-side events. Each event subscription is defined by a certain key.

Event
An event is a state change or a system update that triggers the action of other systems. To read more about built-in events in Tarantool, check the system events section.
State
A state is an internally stored key-value pair. The key is a string. The value is an arbitrary type that can be encoded as MsgPack. To update a state, use the box.broadcast() function.
Watcher
A watcher is a callback that is invoked when a state change occurs. To register a local watcher, use the box.watch() function. To create a remote watcher, use the watch() function from the net.box module. Note that it is possible to register more than one watcher for the same key.

How a watcher works

First, you register a watcher. After that, the watcher callback is invoked for the first time. In this case, the callback is triggered whether or not the key has already been broadcast. All subsequent invocations are triggered with box.broadcast() called on the remote host. If a watcher is subscribed for a key that has not been broadcast yet, the callback is triggered only once, after the registration of the watcher.

The watcher callback takes two arguments. The first argument is the name of the key for which it was registered. The second one contains current key data. The callback is always invoked in a new fiber. It means that it is allowed to yield in it. A watcher callback is never executed in parallel with itself. If the key is updated while the watcher callback is running, the callback will be invoked again with the new value as soon as it returns.

box.watch and box.broadcast functions can be used before box.cfg.

Below is a list of all functions and pages related to watchers or events.

Name Use
box.watch() Create a local watcher.
conn:watch() Create a watcher for the remote host.
box.broadcast() Update a state.
Built-in events Predefined events in Tarantool

box.watch()

box.watch(key, func)

Subscribe to events broadcast by a local host.

Параметры:
  • key (string) – key name of the event to subscribe to
  • func (function) – callback to invoke when the key value is updated
Return:

a watcher handle. The handle consists of one method – unregister(), which unregisters the watcher.

To read more about watchers, see the Functions for watchers section.

Примечание

Keep in mind that garbage collection of a watcher handle doesn’t lead to the watcher’s destruction. In this case, the watcher remains registered. It is okay to discard the result of watch function if the watcher will never be unregistered.

Example:

-- Broadcast value 42 for the 'foo' key.
box.broadcast('foo', 42)

local log = require('log')
-- Subscribe to updates of the 'foo' key.
local w = box.watch('foo', function(key, value)
    assert(key == 'foo')
    log.info("The box.id value is '%d'", value)
end)

If you don’t need the watcher anymore, you can unregister it using the command below:

w:unregister()

box.broadcast()

box.broadcast(key, value)

Update the value of a particular key and notify all key watchers of the update.

Параметры:
  • key (string) – key name of the event to subscribe to
  • value – any data that can be encoded in MsgPack
Return:

none

Possible errors:

  • The value can’t be encoded as MsgPack.
  • The key refers to a box. system event

Example:

-- Broadcast value 42 for the 'foo' key.
box.broadcast('foo', 42)

System events

Since 2.10.0.

Predefined events have a special naming schema – theirs names always start with the reserved box. prefix. It means that you cannot create new events with it.

The system processes the following events:

In response to each event, the server sends back certain IPROTO fields.

The events are available from the beginning as non-MP_NIL. If a watcher subscribes to a system event before it has been broadcast, it receives an empty table for the event value.

The event is generated when there is a change in any of the values listed in the event. For example, see the parameters in the box.id event below – id, instance_uuid, and replicaset_uuid. Suppose the ìd value (box.info.id) has changed. This triggers the box.info event, which states that the value of box.info.id has changed, while box.info.uuid and box.info.cluster.uuid remain the same.

box.id

Contains identification of the instance. Value changes are rare.

-- box.id value
{
MP_STR “id”: MP_UINT; box.info.id,
MP_STR “instance_uuid”: MP_UUID; box.info.uuid,
MP_STR “replicaset_uuid”: MP_UUID box.info.cluster.uuid,
}

box.status

Contains generic information about the instance status.

{
MP_STR “is_ro”: MP_BOOL box.info.ro,
MP_STR “is_ro_cfg”: MP_BOOL box.cfg.read_only,
MP_STR “status”: MP_STR box.info.status,
}

box.election

Contains fields of box.info.election that are necessary to find out the most recent writable leader.

{
MP_STR “term”: MP_UINT box.info.election.term,
MP_STR “role”: MP_STR box.info.election.state,
MP_STR “is_ro”: MP_BOOL box.info.ro,
MP_STR “leader”: MP_UINT box.info.election.leader,
}

box.schema

Contains schema-related data.

{
MP_STR “version”: MP_UINT schema_version,
}

box.shutdown

Contains a boolean value which indicates whether there is an active shutdown request.

The event is generated when the server receives a shutdown request (os.exit() command or SIGTERM signal).

The box.shutdown event is applied for the graceful shutdown protocol. It is a feature which is available since 2.10.0. This protocol is supposed to be used with connectors to signal a client about the upcoming server shutdown and close active connections without broken requests. For more information, refer to the graceful shutdown protocol section.

Usage example

local conn = net.box.connect(URI)
local log = require('log')
-- Subscribe to updates of key 'box.id'
local w = conn:watch('box.id', function(key, value)
    assert(key == 'box.id')
    log.info("The box.id value is '%s'", value)
end)

If you want to unregister the watcher when it’s no longer needed, use the following command:

w:unregister()

Функция box.once

box.once(key, function[, ...])

Выполнение функции при условии, что она раньше не выполнялась. Передаваемое значение проверяется на предмет того, выполнялась ли функция. Если она выполнялась, ничего не происходит. В противном случае вызывается функция.

See an example of using box.once() in Adding storage code.

Warning: If an error occurs inside box.once() when initializing a database, you can re-execute the failed box.once() block without stopping the database. The solution is to delete the once object from the system space _schema. Say box.space._schema:select{}, find your once object there and delete it.

Когда box.once() используется для инициализации, следует подождать, пока база данных не будет в нужном состоянии (только для чтения или для чтения и записи). Для этого см. функции во Вложенный модуль box.ctl.

Параметры:
  • key (string) – значение для проверки
  • function (function) – функция
  • ... – arguments that must be passed to the function

Примечание

Параметр key сохраняется в системном спейсе _schema после вызова box.once(), чтобы предотвратить повторный вызов по ключу. Эти ключи распространяются на набор реплик. Поэтому одновременный вызов box.once с одинаковыми ключами на двух экземплярах одного набора реплик может быть успешным, но приведет к конфликту транзакций.

Example

The example shows how to re-execute the box.once() block that contains the hello key.

First, check the _schema system space. The _schema space in the example contains two box.once objects – oncebye and oncehello:

app:instance001> box.space._schema:select{}
---
- - ['oncebye']
  - ['oncehello']
  - ['replicaset_name', 'replicaset001']
  - ['replicaset_uuid', '72d2d9bf-5d9f-48c4-ba80-9d657e128fee']
  - ['version', 3, 1, 0]

Delete the oncehello object:

app:instance001> box.space._schema:delete('oncehello')
---
- ['oncehello']
...

After that, check the _schema space again:

app:instance001> box.space._schema:select{}
---
- - ['oncebye']
  - ['replicaset_name', 'replicaset001']
  - ['replicaset_uuid', '72d2d9bf-5d9f-48c4-ba80-9d657e128fee']
  - ['version', 3, 1, 0]
...

To re-execute the function, call the box.once() method again:

app:instance001> box.once('hello', function() end)
---
...

app:instance001> box.space._schema:select{}
---
- - ['oncebye']
  - ['oncehello']
  - ['replicaset_name', 'replicaset001']
  - ['replicaset_uuid', '72d2d9bf-5d9f-48c4-ba80-9d657e128fee']
  - ['version', 3, 1, 0]
...

Функция box.snapshot

box.snapshot()

Memtx

Take a snapshot of all data and store it in snapshot.dir/<latest-lsn>.snap. To take a snapshot, Tarantool first enters the delayed garbage collection mode for all data. In this mode, the Tarantool garbage collector will not remove files which were created before the snapshot started, it will not remove them until the snapshot has finished. To preserve consistency of the primary key, used to iterate over tuples, a copy-on-write technique is employed. If the master process changes part of a primary key, the corresponding process page is split, and the snapshot process obtains an old copy of the page. In effect, the snapshot process uses multi-version concurrency control in order to avoid copying changes which are superseded while it is running.

Since a snapshot is written sequentially, you can expect a very high write performance (averaging to 80MB/second on modern disks), which means an average database instance gets saved in a matter of minutes. You may restrict the speed by changing snapshot.snap_io_rate_limit.

Примечание

При условии, что происходят изменения в родительском индексе в ходе многопоточного обновления данных, будет происходить и расщепление страниц, поэтому возникнет необходимость в наличии дополнительной свободной памяти для выполнения этой команды. В среднем, будет достаточно 10% от memtx_memory. Оператор подождет окончания создания снимка и вернет результат операции.

Примечание

Обновление: До версии 1.6.6 Tarantool процесс создания снимка вызывал клонирование системного процесса (fork), что могло привести к скачкам задержки отклика. Начиная с версии 1.6.6 Tarantool, процесс создания снимка создает вид постоянного просмотра, который и записывается в файл снимка с помощью отдельного потока (поток упреждающей записи в журнал).

Although box.snapshot() does not cause a fork, there is a separate fiber which may produce snapshots at regular intervals – see the discussion of the checkpoint daemon.

Пример:

tarantool> box.info.version
---
- 1.7.0-1216-g73f7154
...
tarantool> box.snapshot()
---
- ok
...
tarantool> box.snapshot()
---
- error: can't save snapshot, errno 17 (File exists)
...

Создание снимка не приводит к записи нового журнала упреждающей записи на сервере. После создания снимка старые WAL-файлы можно удалить, если все реплицируемые данные актуальны. Но WAL-файл на момент начала работы box.snapshot() следует сохранить на случай восстановления, поскольку он содержит записи журнала после начала работы box.snapshot().

Другим способом сохранения снимка будет отправка сигнала SIGUSR1 процессу. Хотя это может быть удобно, не рекомендуется использовать такой метод в автоматическом процессе: сигнал не дает возможность проверить, был ли корректно сделан снимок.

Vinyl

При использовании vinyl’a вставляемые данные складываются в память до тех пор, пока не будет достигнут предел, установленный в параметре vinyl_memory. Затем vinyl автоматически делает дамп на диск. box.snapshot() форсирует создание дампа, чтобы иметь возможность восстановить данные из этой контрольной точки. Файлы снимков хранятся в space_id/index_id/*.run. Таким образом, строго все данные, которые были записаны во время LSN контрольной точки, находятся в *.run файлах на диске, а все операции, которые происходили после контрольной точки, будут записаны в *.xlog. Все файлы дампа, созданные функцией box.snapshot(), консистентны и имеют тот же LSN, что и контрольная точка.

На контрольной точке vinyl также пересматривает журнал метаданных *.vylog, содержащий операции манипуляции с данными, такие как «создать файл» и «удалить файл». Он проходит по логу, удаляет дублирующие операции из памяти и создает новый файл *.vylog, присваивая ему имя в соответствии с vclock новой контрольной точки, оставляя только операци создания. Эта процедура очищает *.vylog и полезна для восстановления, так как имя лога совпадает с именем подписи контрольной точки.

Константа box.NULL

Имеется целый ряд серьезных проблем при использовании значения nil из Lua в таблицах. Например: вы не можете корректно оценить длину таблицы, не являющейся последовательностью. (Узнайте больше о типах данных в Lua и LuaJIT.)

Пример:

tarantool> t = {0, nil, 1, 2, nil}
---
...

tarantool> t
---
- - 0
  - null
  - 1
  - 2
...

tarantool> #t
---
- 4
...

Вывод в консоль t обрабатывает значения nil в середине и в конце таблицы по-разному. Это вызвано неопределённым поведением.

Примечание

Попытка найти длину для разреженного массива в LuaJIT приводит к другому случаю неопределённого поведения.

Для избежания этой проблемы используйте имеющуюся в Tarantool константу box.NULL вместо значения nil. box.NULL является местозаполнителем для значения nil в таблицах с целью сохранения ключа без значения.

Использование box.NULL

box.NULL является значением типа cdata, представляющим нулевой указатель (NULL pointer). Оно подобно msgpack.NULL, json.NULL и yaml.NULL. Таким образом, оно является некоторым не nil значением, даже если является указателем на NULL.

Используйте box.NULL только с NULL, написанным заглавными буквами (box.null является ошибкой).

Примечание

Технически, box.NULL соответствует ffi.cast('void *', 0).

Пример:

tarantool> t = {0, box.NULL, 1, 2, box.NULL}
---
...

tarantool> t
---
- - 0
  - null # cdata
  - 1
  - 2
  - null # cdata
...

tarantool> #t
---
- 5
...

Примечание

Заметьте, что t[2] демонстрирует один и тот же вывод null в обоих примерах. Однако, в данном примере t[2] и t[5] являются типом cdata, в то время как в предыдущем примере их тип был nil.

Важно

Избегайте использования неявных сравнений с обнуляемыми (nullable) значениями при использовании box.NULL. В связи со штатным поведением Lua, возвращение любого результата, кроме false (ложь) или nil (ничто), из выражения условия считается возвращением true (истина). Как и упоминалось ранее, box.NULL является указателем.

Поэтому выражение box.NULL всегда будет расцениваться как true (истина) в случае использования в качестве условия в сравнении. Это означает, что код

if box.NULL then func() end

всегда будет выполнять функцию func() (потому, что условие box.NULL всегда будет не false (ложь) и не nil (ничто)).

Distinction of nil and box.NULL

Используйте выражение x == nil для проверки того, является ли x nil или box.NULL.

Для выяснения того, является ли x в действительности nil, но не box.NULL, используйте следующее условие:

type(x) == 'nil'

Если оно истинно (true), то x – это nil, но не``box.NULL``.

Вы можете использовать следующее выражение для box.NULL:

x == nil and type(x) == 'cdata'

Если вышеуказанное выражение истинно (true), то x – это box.NULL.

Примечание

Конвертируя данные в различные форматы (JSON, YAML, msgpack), вы должны ожидать возможного преобразования всех nil в разреженных массивах в box.NULL. Стоит ответить, что конвертация может происходить неожиданно (например: при отправке данных через net.box или при получении данных из спейсов и т.п.).

tarantool> type(({1, nil, 2})[2])
---
- nil
...

tarantool> type(json.decode(json.encode({1, nil, 2}))[2])
---
- cdata
...

Вы должны ожидать подобное поведение и использовать соответствующее выражение условия. Используйте явное сравнение x == nil для проверки на отсутствующее значение (NULL) в обнуляемых (nullable) переменных. Оно позволит обнаружить как nil, так и box.NULL.

Модуль buffer

Модуль buffer возвращает буфер, допускающий динамическое изменение размера, который используется только в качестве опции для методов модуля net.box или модуля msgpack.

Как правило, модуль net.box возвращает Lua-таблицу. Если используется опция buffer, то методы модуля net.box возвращают неформатированную строку строку MsgPack. Это экономит время работы на сервере, если в клиентском приложении есть собственная процедура декодирования MsgPack-строк.

Буфер использует четыре указателя для управления его мощностью:

buffer.ibuf()

Создать новый буфер.

Пример:

В этом примере мы покажем, что использование буфера позволит вам сохранить данные в том же формате, в котором они пришли с сервера. Так что если получить данные с сервера нужно только для отправки куда-то дальше, то с буфером это будет гораздо быстрее.

box.cfg{listen = 3301}
buffer = require('buffer')
net_box = require('net.box')
msgpack = require('msgpack')

box.schema.space.create('tester')
box.space.tester:create_index('primary')
box.space.tester:insert({1, 'ABCDE', 12345})

box.schema.user.create('usr1', {password = 'pwd1'})
box.schema.user.grant('usr1', 'read,write,execute', 'space', 'tester')

ibuf = buffer.ibuf()

conn = net_box.connect('usr1:pwd1@localhost:3301')
conn.space.tester:select({}, {buffer=ibuf})

msgpack.decode_unchecked(ibuf.rpos)

Результат последнего запроса выглядит следующим образом:

tarantool> msgpack.decode_unchecked(ibuf.rpos)
---
- {48: [['ABCDE', 12345]]}
- 'cdata<char *>: 0x7f97ba10c041'
...

Примечание

До версии 1.7.7 Tarantool в данном случае следует использовать функцию msgpack.ibuf_decode(ibuf.rpos). Начиная с версии 1.7.7 Tarantool , ibuf_decode объявлена устаревшей.

object buffer_object
buffer_object:alloc(size)

Аллоцировать size байтов для buffer_object’а.

Параметры:
  • size (number) – количество байтов для аллоцирования
возвращает:

wpos
buffer_object:capacity()

Вернуть мощность buffer_object’а.

возвращает:epos - buf
buffer_object:checksize(size)

Проверить, доступно ли size байтов для чтения из buffer_object’а.

Параметры:
  • size (number) – память в байтах для проверки
возвращает:

rpos
buffer_object:pos()

Вернуть размер участка, занятого данными.

возвращает:rpos - buf
buffer_object:read(size)

Прочитать size байтов из буфера.

buffer_object:recycle()

Очистить слоты памяти, выделенные для buffer_object’а.

tarantool> ibuf:recycle()
---
...
tarantool> ibuf.buf, ibuf.rpos, ibuf.wpos, ibuf.epos
---
- 'cdata<char *>: NULL'
- 'cdata<char *>: NULL'
- 'cdata<char *>: NULL'
- 'cdata<char *>: NULL'
...
buffer_object:reset()

Очистить слоты памяти, использованные buffer_object’ом. Этот метод позволяет сохранить буфер, но убрать из него все данные. Это полезно, если вы собираетесь использовать буфер дальше.

tarantool> ibuf:reset()
---
...
tarantool> ibuf.buf, ibuf.rpos, ibuf.wpos, ibuf.epos
---
- 'cdata<char *>: 0x010cc28030'
- 'cdata<char *>: 0x010cc28030'
- 'cdata<char *>: 0x010cc28030'
- 'cdata<char *>: 0x010cc2c000'
...
buffer_object:reserve(size)

Зарезервировать память для buffer_object. Проверить, достаточно ли памяти, чтобы записать size байтов после wpos. Если нет, epos будет сдвигаться, пока size байтов не будет доступно.

buffer_object:size()

Вернуть участок, доступный для чтения данных.

возвращает:wpos - rpos
buffer_object:unused()

Вернуть участок, доступный для записи данных.

возвращает:epos - wpos

Модуль buffer и skip_header

В примере из предыдущего раздела

tarantool> msgpack.decode_unchecked(ibuf.rpos)
---
- {48: [['ABCDE', 12345]]}
- 'cdata<char *>: 0x7f97ba10c041'
...

было показано, что обычно net.box ответ включает в себя заголовок – 48 (в шестнадцатиричной системе – 30), который является ключом для IPROTO_DATA. Но в некоторых ситуациях, например, при передаче буфера в функцию C, которая ожидает массив байт MsgPack без заголовка, заголовок можно пропустить. Это делается путем указания skip_header=true в качестве опции conn.space.space-name:select{…} или conn.space.space-name:insert{…} или conn.space.space-name:replace{…} или conn.space.space-name:update{…} или conn.space.space-name:upsert{…} или conn.space.space-name:delete{…}. По умолчанию skip_header=false.

Ниже приведен конец того же примера, но с использованием skip_header=true.

ibuf = buffer.ibuf()

conn = net_box.connect('usr1:pwd1@localhost:3301')
conn.space.tester:select({}, {buffer=ibuf, skip_header=true})

msgpack.decode_unchecked(ibuf.rpos)

Результат последнего запроса выглядит следующим образом:

tarantool> msgpack.decode_unchecked(ibuf.rpos)
---
- {48: [['ABCDE', 12345]]}
- 'cdata<char *>: 0x7f97ba10c041'
...

Заметьте, что заголовок IPROTO_DATA (48) ушел.

Результат остается внутри массива, что видно из того, что он заключен в квадратные скобки. Пропустить заголовок массива можно и функцией msgpack.decode_array_header().

Module checks

Since: 2.11.0

The checks module provides the ability to check the types of arguments passed to a Lua function. You need to call the checks(type_1, …) function inside the target Lua function and pass one or more type qualifiers to check the corresponding argument types. There are two types of type qualifiers:

Примечание

For earlier versions, you can install the checks module from the Tarantool rocks repository.

Loading checks

In Tarantool 2.11.0 and later versions, the checks API is available in a script without loading the module.

For earlier versions, you need to install the checks module from the Tarantool rocks repository and load the module using the require() directive:

local checks = require('checks')

Number of arguments to check

For each argument to check, you need to specify its own type qualifier in the checks(type_1, …) function.

One argument

In the example below, the checks function accepts a string type qualifier to verify that only a string value can be passed to the greet function. Otherwise, an error is raised.

function greet(name)
    checks('string')
    return 'Hello, ' .. name
end
--[[
greet('John')
-- returns 'Hello, John'

greet(123)
-- raises an error: bad argument #1 to nil (string expected, got number)
--]]

Multiple arguments

To check the types of several arguments, you need to pass the corresponding type qualifiers to the checks function. In the example below, both arguments should be string values.

function greet_fullname(firstname, lastname)
    checks('string', 'string')
    return 'Hello, ' .. firstname .. ' ' .. lastname
end
--[[
greet_fullname('John', 'Smith')
-- returns 'Hello, John Smith'

greet_fullname('John', 1)
-- raises an error: bad argument #2 to nil (string expected, got number)
--]]

To skip checking specific arguments, use the ? placeholder.

Variable number of arguments

You can check the types of explicitly specified arguments for functions that accept a variable number of arguments.

function extra_arguments_num(a, b, ...)
    checks('string', 'number')
    return select('#', ...)
end
--[[
extra_arguments_num('a', 2, 'c')
-- returns 1

extra_arguments_num('a', 'b', 'c')
-- raises an error: bad argument #1 to nil (string expected, got number)
--]]

String type qualifier

This section describes how to check a specific argument type using a string type qualifier:

Supported types

Lua types

A string type qualifier can accept any of the Lua types, for example, string, number, table, or nil. In the example below, the checks function accepts string to validate that only a string value can be passed to the greet function.

function greet(name)
    checks('string')
    return 'Hello, ' .. name
end
--[[
greet('John')
-- returns 'Hello, John'

greet(123)
-- raises an error: bad argument #1 to nil (string expected, got number)
--]]

Tarantool types

You can use Tarantool-specific types in a string qualifier. The example below shows how to check that a function argument is a decimal value.

local decimal = require('decimal')
function sqrt(value)
    checks('decimal')
    return decimal.sqrt(value)
end
--[[
sqrt(decimal.new(16))
-- returns 4

sqrt(16)
-- raises an error: bad argument #1 to nil (decimal expected, got number)
--]]

This table lists all the checks available for Tarantool types:

Check Description See also
checks('datetime') Check whether the specified value is datetime_object checkers.datetime(value)
checks('decimal') Check whether the specified value has the decimal type checkers.decimal(value)
checks('error') Check whether the specified value is error_object checkers.error(value)
checks('int64') Check whether the specified value is an int64 value checkers.int64(value)
checks('interval') Check whether the specified value is interval_object checkers.interval(value)
checks('tuple') Check whether the specified value is a tuple checkers.tuple(value)
checks('uint64') Check whether the specified value is a uint64 value checkers.uint64(value)
checks('uuid') Check whether the specified value is uuid_object checkers.uuid(value)
checks('uuid_bin') Check whether the specified value is uuid represented by a 16-byte binary string checkers.uuid_bin(value)
checks('uuid_str') Check whether the specified value is uuid represented by a 36-byte hexadecimal string checkers.uuid_str(value)

Custom function

A string type qualifier can accept the name of a custom function that performs arbitrary validations. To achieve this, create a function returning true if the value is valid and add this function to the checkers table.

The example below shows how to use the positive function to check that an argument value is a positive number.

function checkers.positive(value)
    return (type(value) == 'number') and (value > 0)
end

function get_doubled_number(value)
    checks('positive')
    return value * 2
end
--[[
get_doubled_number(10)
-- returns 20

get_doubled_number(-5)
-- raises an error: bad argument #1 to nil (positive expected, got number)
--]]

Metatable type

A string qualifier can accept a value stored in the __type field of the argument metatable.

local blue = setmetatable({ 0, 0, 255 }, { __type = 'color' })
function get_blue_value(color)
    checks('color')
    return color[3]
end
--[[
get_blue_value(blue)
-- returns 255

get_blue_value({0, 0, 255})
-- raises an error: bad argument #1 to nil (color expected, got table)
--]]

Union types

To allow an argument to accept several types (a union type), concatenate type names with a pipe (|). In the example below, the argument can be both a number and string value.

function get_argument_type(value)
    checks('number|string')
    return type(value)
end
--[[
get_argument_type(1)
-- returns 'number'

get_argument_type('key1')
-- returns 'string'

get_argument_type(true)
-- raises an error: bad argument #1 to nil (number|string expected, got boolean)
--]]

Optional types

To make any of the supported types optional, prefix its name with a question mark (?). In the example below, the name argument is optional. This means that the greet function can accept string and nil values.

function greet(name)
    checks('?string')
    if name ~= nil then
        return 'Hello, ' .. name
    else
        return 'Hello from Tarantool'
    end
end
--[[
greet('John')
-- returns 'Hello, John'

greet()
-- returns 'Hello from Tarantool'

greet(123)
-- raises an error: bad argument #1 to nil (string expected, got number)
--]]

As for a specific type, you can make a union type value optional: ?number|string.

Skipping argument checking

You can skip checking of the specified arguments using the question mark (?) placeholder. In this case, the argument can be any type.

function greet_fullname_any(firstname, lastname)
    checks('string', '?')
    return 'Hello, ' .. firstname .. ' ' .. tostring(lastname)
end
--[[
greet_fullname_any('John', 'Doe')
-- returns 'Hello, John Doe'

greet_fullname_any('John', 1)
-- returns 'Hello, John 1'
--]]

Table type qualifier

A table type qualifier checks whether the values of a table passed as an argument conform to the specified types. In this case, the following checks are made:

The code below checks that the first and second table values have the string and number types.

function configure_connection(options)
    checks({ 'string', 'number' })
    local ip_address = options[1] or '127.0.0.1'
    local port = options[2] or 3301
    return ip_address .. ':' .. port
end
--[[
configure_connection({'0.0.0.0', 3303})
-- returns '0.0.0.0:3303'

configure_connection({'0.0.0.0', '3303'})
-- raises an error: bad argument options[2] to nil (number expected, got string)
--]]

In the next example, the same checks are made for the specified keys.

function configure_connection_opts(options)
    checks({ ip_address = 'string', port = 'number' })
    local ip_address = options.ip_address or '127.0.0.1'
    local port = options.port or 3301
    return ip_address .. ':' .. port
end
--[[
configure_connection_opts({ip_address = '0.0.0.0', port = 3303})
-- returns '0.0.0.0:3303'

configure_connection_opts({ip_address = '0.0.0.0', port = '3303'})
-- raises an error: bad argument options.port to nil (number expected, got string)

configure_connection_opts({login = 'testuser', ip_address = '0.0.0.0', port = 3303})
-- raises an error: unexpected argument options.login to nil
--]]

Примечание

Table qualifiers can be nested and use tables, too.

API Reference

Members  
checks() When called inside a function, checks that the function’s arguments conform to the specified types
checkers A global variable that provides access to checkers for different types

checks()

checks(type_1, ...)

When called inside a function, checks that the function’s arguments conform to the specified types.

Параметры:
  • type_1 (string/table) – a string or table type qualifier used to check the argument type
  • ... – optional type qualifiers used to check the types of other arguments

checkers

The checkers global variable provides access to checkers for different types. You can use this variable to add a custom checker that performs arbitrary validations.

Примечание

The checkers variable also provides access to checkers for Tarantool-specific types. These checkers can be used in a custom checker.

checkers.datetime(value)

Check whether the specified value is datetime_object.

Параметры:
  • value (any) – the value to check the type for
Return:

true if the specified value is datetime_object; otherwise, false
Rtype:

boolean

Example

local datetime = require('datetime')
local is_datetime = checkers.datetime(datetime.new { day = 1, month = 6, year = 2023 })
local is_interval = checkers.interval(datetime.interval.new { day = 1 })
checkers.decimal(value)

Check whether the specified value has the decimal type.

Параметры:
  • value (any) – the value to check the type for
Return:

true if the specified value has the decimal type; otherwise, false
Rtype:

boolean

Example

local decimal = require('decimal')
local is_decimal = checkers.decimal(decimal.new(16))
checkers.error(value)

Check whether the specified value is error_object.

Параметры:
  • value (any) – the value to check the type for
Return:

true if the specified value is error_object; otherwise, false
Rtype:

boolean

Example

local server_error = box.error.new({ code = 500, reason = 'Server error' })
local is_error = checkers.error(server_error)
checkers.int64(value)

Check whether the specified value is one of the following int64 values:

  • a Lua number in a range from -2^53+1 to 2^53-1 (inclusive)
  • Lua cdata ctype<uint64_t> in a range from 0 to LLONG_MAX
  • Lua cdata ctype<int64_t>
Параметры:
  • value (any) – the value to check the type for
Return:

true if the specified value is an int64 value; otherwise, false
Rtype:

boolean

Example

local is_int64 = checkers.int64(-1024)
local is_uint64 = checkers.uint64(2048)
checkers.interval(value)

Check whether the specified value is interval_object.

Параметры:
  • value (any) – the value to check the type for
Return:

true if the specified value is interval_object; otherwise, false
Rtype:

boolean

Example

local datetime = require('datetime')
local is_datetime = checkers.datetime(datetime.new { day = 1, month = 6, year = 2023 })
local is_interval = checkers.interval(datetime.interval.new { day = 1 })
checkers.tuple(value)

Check whether the specified value is a tuple.

Параметры:
  • value (any) – the value to check the type for
Return:

true if the specified value is a tuple; otherwise, false
Rtype:

boolean

Example

local is_tuple = checkers.tuple(box.tuple.new{1, 'The Beatles', 1960})
checkers.uint64(value)

Check whether the specified value is one of the following uint64 values:

  • a Lua number in a range from 0 to 2^53-1 (inclusive)
  • Lua cdata ctype<uint64_t>
  • Lua cdata ctype<int64_t> in range from 0 to LLONG_MAX
Параметры:
  • value (any) – the value to check the type for
Return:

true if the specified value is an uint64 value; otherwise, false
Rtype:

boolean

Example

local is_int64 = checkers.int64(-1024)
local is_uint64 = checkers.uint64(2048)
checkers.uuid(value)

Check whether the specified value is uuid_object.

Параметры:
  • value (any) – the value to check the type for
Return:

true if the specified value is uuid_object; otherwise, false
Rtype:

boolean

Example

local uuid = require('uuid')
local is_uuid = checkers.uuid(uuid())
local is_uuid_bin = checkers.uuid_bin(uuid.bin())
local is_uuid_str = checkers.uuid_str(uuid.str())
checkers.uuid_bin(value)

Check whether the specified value is uuid represented by a 16-byte binary string.

Параметры:
  • value (any) – the value to check the type for
Return:

true if the specified value is uuid represented by a 16-byte binary string; otherwise, false
Rtype:

boolean

See also: uuid(value)

checkers.uuid_str(value)

Check whether the specified value is uuid represented by a 36-byte hexadecimal string.

Параметры:
  • value (any) – the value to check the type for
Return:

true if the specified value is uuid represented by a 36-byte hexadecimal string; otherwise, false
Rtype:

boolean

See also: uuid(value)

Модуль clock

Общие сведения

Модуль clock возвращает значения времени, полученные из функции Posix / C CLOCK_GETTIME или аналогичной. Большинство функций модуля возвращают число секунд; функции, названия которых заканчиваются на «64», возвращают 64-разрядное число наносекунд.

Указатель

Ниже приведен перечень всех функций модуля clock.

Имя Назначение
clock.time()
clock.realtime()		 Получение физического времени в секундах
clock.time64()
clock.realtime64()		 Получение физического времени в наносекундах
clock.monotonic() Получение монотонного времени в секундах
clock.monotonic64() Получение монотонного времени в наносекундах
clock.proc() Получение времени процессора в секундах
clock.proc64() Получение времени процессора в наносекундах
clock.thread() Получение рабочего времени потока в секундах
clock.thread64() Получение рабочего времени потока в наносекундах
clock.bench() Измерение времени, которое функция проводит в процессоре
clock.time()
clock.time64()
clock.realtime()
clock.realtime64()

Физическое время в секундах. Получено из C-функции clock_gettime(CLOCK_REALTIME).

возвращает:секунды или наносекунды с начала отсчета (1970-01-01 00:00:00), значение корректируется.
тип возвращаемого значения:
 number or cdata (ctype<int64_t>)

Пример:

-- Результатом будет примерное число лет с 1970.
clock = require('clock')
print(clock.time() / (365*24*60*60))

См. также fiber.time64 и стандартную Lua-функцию os.clock.

clock.monotonic()
clock.monotonic64()

The monotonic time. Derived from C function clock_gettime(CLOCK_MONOTONIC). Monotonic time is similar to wall clock time but is not affected by changes to or from daylight saving time, or by changes done by a user. This is the best function to use with benchmarks that need to calculate elapsed time.

возвращает:секунды или наносекунды с момента последней загрузки компьютера.
тип возвращаемого значения:
 number or cdata (ctype<int64_t>)

Пример:

-- Результатом будет число наносекунд с запуска.
clock = require('clock')
print(clock.monotonic64())
clock.proc()
clock.proc64()

Время процессора. Получено из C-функции clock_gettime(CLOCK_PROCESS_CPUTIME_ID). Такую функцию лучше всего использовать для эталонного тестирования, где необходимо рассчитать время, затраченное на процессоре.

возвращает:секунды или наносекунды с момента начала работы процессора.
тип возвращаемого значения:
 number or cdata (ctype<int64_t>)

Пример:

-- Результатом будет число наносекунд с запуска процессора.
clock = require('clock')
print(clock.proc64())
clock.thread()
clock.thread64()

Рабочее время потока. Получено из C-функции clock_gettime(CLOCK_THREAD_CPUTIME_ID). Такую функцию лучше всего использовать для эталонного тестирования, где необходимо рассчитать время, затраченное потоком на процессоре.

возвращает:секунды или наносекунды с момента начала работы потока процессора транзакций.
тип возвращаемого значения:
 number or cdata (ctype<int64_t>)

Пример:

-- Результатом будет число секунд с момента начала работы потока.
clock = require('clock')
print(clock.thread64())
clock.bench(function[, ...])

Время, которое функция проводит в процессоре. Данная функция использует clock.proc(), то есть рассчитывает затраченное процессором время. Таким образом, она не используется для отображения фактически затраченного времени.

Параметры:
  • function (function) – функция или ссылка на функцию
  • ... – значения, которые необходимы для функции.
возвращает:

таблица. Первый элемент – время работы процессора в секундах, второй элемент – то, что возвращает функция.

Пример:

-- Эталонное тестирование функции, которая находится в спящем режиме в течение 10 секунд.
-- NB: bench() не будет рассчитывать время сна.
-- Поэтому вернется значение, которое будет {число менее 10, 88}.
clock = require('clock')
fiber = require('fiber')
function f(param)
  fiber.sleep(param)
  return 88
end
clock.bench(f, 10)

Module compat

The usual way to handle compatibility problems is to introduce an option for a new behavior and leave the old one by default. It is not always the perfect way.

Sometimes developers want to keep the old behavior for existing applications and offer the new behavior by default for the new ones. For example, the old behavior is known to be problematic, or less safe, or it doesn’t correspond to user expectations. In contrast, the user doesn’t always read all the documentation and often assumes good defaults. It was decided to introduce a compatibility module to provide a direct way to deprecate unwanted behavior.

The compat module is basically a global table of options with additional verbose interface and helper functions. There are three stages of changing behavior:

  1. Old behavior by default.
  2. New behavior by default.
  3. New behavior is frozen and the old behavior is removed.

During the first two stages, a user can toggle options via the interface and change the behavior according to one’s needs. At the last stage, the old behavior is removed from the codebase, and the option is marked as obsolete. Because compat is a global instance, options can be hardcoded into it or added in runtime, for example, by external module.

Options are switched to the next stage in major releases. In this way, developers are able to adapt to the new standard behavior and test it before switching to the next release. If something is broken by a new Tarantool version, a developer can still have a way to fix it by a simple config change, that is, explicitly select the old behavior.

Consider example below:

Basic usage

If you want to explicitly secure every behavior in compat, you can do it manually, and then call compat.dump() to get a Lua command that sets up the compat with all the options selected. You should place this commands at the beginning of code in your init.lua file. In this way, you are guaranteed to get the same behavior on any other Tarantool version. See a tutorial on using compat for more examples.

Configuration options

Another way to handle compatibility issues is setting the compat.* configuration options. Similarly to the compat Lua module options, the configuration options can have values new and old. The set of configuration options matches the set of options available in the compat module.

Below is an example fragment of a YAML configuration file:

compat:
  box_space_max: 'new'
  sql_seq_scan_default: 'old'
  fiber_slice_default: 'old'
  binary_data_decoding: 'new'

Learn more in the Configuration reference.

Options

Below are the available compat options:

JSON encode escape forward slash

Option: json_escape_forward_slash

For some reason, in the upstream lua_cjson, the „/“ sign is escaped. But according to the rfc4627 standard, it is unnecessary and questionably compatible with other implementations.

Old and new behavior

By toggling the json_escape_forward_slash compat option, you can chose either the json encoder escapes the „/“ sign or it does not:

tarantool> require('compat').json_escape_forward_slash = 'old'
---
...

tarantool> require('json').encode('foo/bar')
---
- '"foo\/bar"'
...

tarantool> require('compat').json_escape_forward_slash = 'new'
---
...

tarantool> require('json').encode('foo/bar')
---
- '"foo/bar"'
...

The option affects both the global serializer instance and serializers created with json.new(). It also affects the way log messages are encoded when written to the log in the json format (the box.cfg.log_format option is set to „json“).

Known compatibility issues

At this point, no incompatible modules are known.

Detecting issues in your codebase

Both encoding styles are correct from the JSON standard standpoint, but if your module relies on encodings results bytewise, it may break with this change. Be cautious if you do the following:

Lua-YAML prettier multiline output

Option: yaml_pretty_multiline

The lua-yaml encoder selects the string style automatically, but in Tarantool context, it can be beneficial to enforce them, for example, for better readability. The yaml_pretty_multiline compat option allows to encode multiline strings in a block style.

Old and new behavior

The compat module allows you to chose between the lua-yaml encodes multiline strings as usual or in the enforced block scalar style:

tarantool> compat.yaml_pretty_multiline = 'old'
---
...

tarantool> return "Title: xxx\n- Item 1\n- Item 2\n"
---
- 'Title: xxx

  - Item 1

  - Item 2

  '
...

tarantool> compat.yaml_pretty_multiline = 'new'
---
...

tarantool> return "Title: xxx\n- Item 1\n- Item 2\n"
---
- |
  Title: xxx
  - Item 1
  - Item 2
...

You can select the new/old behavior in compat. It affects the global YAML encoder.

Known compatibility issues

At this point, no incompatible modules are known.

Detecting issues in your codebase

Both encoding styles are correct from the YAML standard standpoint, but if your module relies on encodings results bytewise, it may break with this change. Be cautious if you do the following:

Fiber channel close mode

Option: fiber_channel_close_mode

Before the change, there was an unexpected behavior when using channel:close() because it closed the channel entirely and discarded all unread events.

Old and new behavior

The compat module allows you chose between the channel force and graceful closing. The latter is a new behavior.

tarantool> compat = require('compat')
---
...

tarantool> compat
---
- - yaml_pretty_multiline: default (old)
  - json_escape_forward_slash: default (old)
  - fiber_channel_close_mode: default (old)
...

tarantool> fiber = require('fiber')
---
...

tarantool> ch = fiber.channel(10)
---
...

tarantool> ch:put('one')
---
- true
...

tarantool> ch:put('two')
---
- true
...

tarantool> ch:get()
---
- one
...

tarantool> ch:close()
---
...

tarantool> ch:get()
---
- null
...

tarantool> compat.fiber_channel_close_mode = 'new'
---
...

tarantool> ch = fiber.channel(10)
---
...

tarantool> ch:put('one')
---
- true
...

tarantool> ch:put('two')
---
- true
...

tarantool> ch:get()
---
- one
...

tarantool> ch:close()
---
...

tarantool> ch:get()
---
- two
...

tarantool> ch:get()
---
- null
...

You can select new/old behavior in compat. It will affect all existing channels and the future ones.

Known compatibility issues

At this point, no incompatible modules are known.

Detecting issues in your codebase

The new behavior is mostly backward compatible. The only known problem that can appear is when the code relies on channel being entirely closed after ch:close() and ch:get() returning nil.

Default value for replication_sync_timeout

Option: box_cfg_replication_sync_timeout

Having a non-zero replication_sync_timeout gives a user the false assumption that the box.cfg{replication = ...} call returns only when the configured node is synced with all the other nodes. This is mostly true for the big replication_sync_timeout values, but it is not 100% guaranteed. In other words, a user still has to check if the node is synced, or the sync just timed out. Besides, while replication_sync_timeout is ticking, you cannot reconfigure box with another box.cfg call, which hardens reconfiguration.

It is decided to set the replication_sync_timeout to zero by default.

Old and new behavior

The compat module allows you to choose between

It is important to set the desired behavior before the initial box.cfg{} call to take effect for it.

tarantool> compat.box_cfg_replication_sync_timeout = 'new'
---
...
tarantool> box.cfg{}
---
...
tarantool> box.cfg.replication_sync_timeout
---
- 0
...
tarantool> compat.box_cfg_replication_sync_timeout = 'old'
---
- error: 'builtin/box/load_cfg.lua:253: The compat  option ''box_cfg_replication_sync_timeout''
    takes effect only before the initial box.cfg() call'
...

A fresh Tarantool run:

tarantool> compat.box_cfg_replication_sync_timeout = 'old'
---
...
tarantool> box.cfg{}
---
...
tarantool> box.cfg.replication_sync_timeout
---
- 300
...

Known compatibility issues

At this point, no incompatible modules are known.

Detecting issues in your codebase

We expect issues with a user assuming that the node is not in the orphan state (box.info.status ~= "orphan") after the box.cfg{replication=...} call returns. This is not true with the new behaviour. To simulate the old behavior, one may add a box.ctl.wait_rw() call after the box.cfg{} call. box.ctl.wait_rw() returns only when the node becomes writable, and hence is not an orphan.

Default value for sql_seq_scan session setting

Option: sql_seq_scan_default

The default value for the sql_seq_scan session setting will be set to false starting with Tarantool 3.0. To be able to return the behavior to the old default, a new compat option is introduced.

Old and new behavior

Old behavior: SELECT scan queries are always allowed.

New behavior: SELECT scan queries are only allowed if the SEQSCAN keyword is used correctly.

Note that the sql_seq_scan_default compat option only affects sessions during initialization. It means that you should set sql_seq_scan_default before running box.cfg{} or creating a new session. Also, a new session created before executing box.cfg{} will not be affected by the value of the compat option.

Examples of setting the option before execution of box.cfg{}:

tarantool> require('compat').sql_seq_scan_default = 'new'
---
...

tarantool> box.cfg{log_level = 1}
---
...

tarantool> box.space._session_settings:get{'sql_seq_scan'}
---
- ['sql_seq_scan', false]
...

tarantool> require('compat').sql_seq_scan_default = 'old'
---
...

tarantool> box.cfg{log_level = 1}
---
...

tarantool> box.space._session_settings:get{'sql_seq_scan'}
---
- ['sql_seq_scan', true]
...

Examples of setting the option before creation of a new session after execution of box.cfg{}:

tarantool> box.cfg{log_level = 1, listen = 3301}
---
...

tarantool> require('compat').sql_seq_scan_default = 'new'
---
...

tarantool> cn = require('net.box').connect(box.cfg.listen)
---
...

tarantool> cn.space._session_settings:get{'sql_seq_scan'}
---
- ['sql_seq_scan', false]
...

tarantool> require('tarantool').compat.sql_seq_scan_default = 'old'
---
...

tarantool> cn = require('net.box').connect(box.cfg.listen)
---
...

tarantool> cn.space._session_settings:get{'sql_seq_scan'}
---
- ['sql_seq_scan', true]
...

Known compatibility issues

At this point, no incompatible modules are known.

Detecting issues in your codebase

We expect most SELECTs that do not use indexes to fail after the sql_seq_scan session setting is set to false. The best way to avoid this is to refactor the query to use indexes. To understand if SELECT uses indexes, you can use EXPLAIN QUERY PLAN. If SEARCH TABLE is specified, the index is used. If it says SCAN TABLE, the index is not used.

You can use the SEQSCAN keyword to manually allow scanning queries. Or you can set the sql_seq_scan session setting to true to allow all scanning queries.

Default value for max fiber slice

Option: fiber_slice_default

The max fiber slice specifies the max fiber execution time without yield before a warning is logged or an error is raised. It is set with the fiber.set_max_slice() function. The new compat option – fiber_slice_default – controls the default value of the max fiber slice.

Old and new behavior

The old default value for the max fiber slice is infinity (no warnings or errors). The new default value is {warn = 0.5, err = 1.0}. To use the new behavior, set fiber_slice_default to new as follows:

compat = require('compat')
compat.fiber_slice_default = 'new'

Known compatibility issues

At this point, no incompatible modules are known.

Detecting issues in your codebase

If you see a warning like this in the log:

fiber has not yielded for more than 0.500 seconds,

or the following error is raised unexpectedly by a box function

error: fiber slice is exceeded,

then your application has a fiber that may exceed its slice and fail.

First, make sure that fiber.yield() is used for this fiber to transfer control to another fiber. You can also extend the fiber slice with the fiber.extend_slice(slice) function.

Decoding binary objects

Option: binary_data_decoding

Starting from version 3.0, Tarantool has the varbinary module for handling binary objects of arbitrary lengths. The binary_data_decoding compat option allows to define the format in which varbinary field values are returned for handling in Lua: plain strings or varbinary objects.

Old and new behavior

New behavior: varbinary field values are returned as varbinary objects.

tarantool> compat.binary_data_decoding = 'new'
---
...

tarantool> varbinary.is(msgpack.decode('\xC4\x02\xFF\xFE'))
---
- true
...

Old behavior: varbinary field values are returned as plain strings.

tarantool> compat.binary_data_decoding = 'old'
---
...

tarantool> varbinary.is(msgpack.decode('\xC4\x02\xFF\xFE'))
---
- false
...

tarantool> varbinary.is(yaml.decode('!!binary //4='))
---
- false
...

Known compatibility issues

At this point, no incompatible modules are known.

Detecting issues in your codebase

String manipulation methods, such as string.sub() or string.match() are not defined for varbinary objects. Thus, if you use such methods on results of binary data decoding from MsgPack or YAML, convert them to strings explicitly using the tostring() method.

Tutorial: Module compat

This tutorial covers the following compat module API and its usage:

Listing options

The options list is serialized in the interactive console with additional details for user convenience:

tarantool> compat = require('compat')
---
...

tarantool> compat
---
- - json_escape_forward_slash: new
- - option_2: old
- - option_default_old: default (old)
- - option_default_new: default (new)
...

Listing options details

tarantool> compat.option_default_new
---
- current: old
default: new
brief: <...>
...

Changing option value

You can do it directly, or by passing a table with option-value. Possible values to assign are „new“ , „old“, and „default“.

tarantool> compat.json_escape_forward_slash = 'old'
---
...

tarantool> compat{json_escape_forward_slash = 'new', option_2 = 'default'}
---
...

Restoring defaults

By setting „default“ value to an option:

tarantool> compat.option_2 = 'default'
---
...

tarantool> compat.option_2
---
- current: default
- default: new
- brief: <...>
...

Getting compat setup with compat.dump()

tarantool> compat({
         >     obsolete_set_explicitly = 'new',
         >     option_set_old = 'old',
         >     option_set_new = 'new'
         > })
---
...

tarantool> compat
---
- - option_set_old: old
- - option_set_new: new
- - option_default_old: default (old)
- - option_default_new: default (new)
...

# Obsolete options are not returned in serialization, but have the following values:
# - obsolete_option_default: default (new)
# - obsolete_set_explicitly: new

# nil does output obsolete unset options as 'default'
tarantool> compat.dump()
---
- require('compat')({
            option_set_old          = 'old',
            option_set_new          = 'new',
            option_default_old      = 'default',
            option_default_new      = 'default',
            obsolete_option_default = 'default', -- obsolete since X.Y
            obsolete_set_explicitly = 'new',     -- obsolete since X.Y
    })
...

# 'current' is the same as nil with default set to current values
tarantool> compat.dump('current')
---
- require('compat')({
            option_set_old          = 'old',
            option_set_new          = 'new',
            option_default_old      = 'old',
            option_default_new      = 'new',
            obsolete_option_default = 'new',     -- obsolete since X.Y
            obsolete_set_explicitly = 'new',     -- obsolete since X.Y
    })
...

# 'new' outputs obsolete as 'new'.
tarantool> compat.dump('new')
---
- require('compat')({
            option_set_old          = 'new',
            option_set_new          = 'new',
            option_default_old      = 'new',
            option_default_new      = 'new',
            obsolete_option_default = 'new',     -- obsolete since X.Y
            obsolete_set_explicitly = 'new',     -- obsolete since X.Y
    })
...

# 'old' outputs obsolete options as 'new'.
tarantool> compat.dump('old')
---
- require('compat')({
            option_set_old          = 'old',
            option_set_new          = 'old',
            option_default_old      = 'old',
            option_default_new      = 'old',
            obsolete_option_default = 'new',     -- obsolete since X.Y
            obsolete_set_explicitly = 'new',     -- obsolete since X.Y
    })
...

# 'default' does output obsolete options as default.
tarantool> dump('default')
---
- require('compat')({
            option_set_old          = 'default',
            option_set_new          = 'default',
            option_default_old      = 'default',
            option_default_new      = 'default',
            obsolete_option_default = 'default', -- obsoleted since X.Y
            obsolete_set_explicitly = 'default', -- obsoleted since X.Y
    })
...

Setting all options to a specific value with compat.dump()

tarantool> compat.dump('new')
---
- require('compat')({
      option_2 = 'new',
      json_escape_forward_slash = 'new',
  })
...
tarantool> require('compat')({
      option_2 = 'new',
      json_escape_forward_slash = 'new',
  })
---
...

tarantool> compat
---
- - json_escape_forward_slash: new
- - option_2: new
...

Adding an option during runtime

User must provide a table with:

Option hot reload:

You can change an existing option in runtime using add_option(), it will update all the fields but keep currently selected behavior if any. The new action will be called afterwards.

tarantool> compat.add_option{
                 name = 'option_4',
                 default = 'new',
                 brief = "<...>",
                 obsolete = nil,          -- you can explicitly mark the option as non-obsolete
                 action = function(is_new)
                      print(("option_4 action was called with is_new = %s!"):format(is_new))
                 end,
                 run_action_now = true
           }
option_4 postaction was called with is_new = true!
---
...

tarantool> compat.add_option{             -- hot reload of option_4
                 name = 'option_4',
                 default = 'old',         -- different default
                 brief = "<...>",
                 action = function(is_new)
                      print(("new option_4 action was called with is_new = %s!"):format(is_new))
                 end
           }
---
...         -- action is not called by default

Module compress

Enterprise Edition

This module is a part of the Enterprise Edition.

Since: 2.11.0

The compress module provides a set of submodules for compressing and decompressing data using different algorithms:

Submodule compress.zlib

Enterprise Edition

This submodule is a part of the Enterprise Edition.

Overview

The compress.zlib submodule provides the ability to compress and decompress data using the zlib algorithm. You can use the zlib compressor as follows:

  1. Create a compressor instance using the compress.zlib.new() function:

    local zlib_compressor = require('compress.zlib').new()
-- or --
local zlib_compressor = require('compress').zlib.new()

    Optionally, you can pass compression options (zlib_opts) specific for zlib:

    local zlib_compressor = require('compress.zlib').new({
    level = 5,
    mem_level = 5,
    strategy = 'filtered'
})

  2. To compress the specified data, use the compress() method:

    compressed_data = zlib_compressor:compress('Hello world!')

  3. To decompress data, call decompress():

    decompressed_data = zlib_compressor:decompress(compressed_data)

API Reference

Functions  
compress.zlib.new() Create a zlib compressor instance.
Objects  
zlib_compressor A zlib compressor instance.
zlib_opts Configuration options of the zlib compressor.

compress.zlib.new()

compress.zlib.new([zlib_opts])

Create a zlib compressor instance.

Параметры:
Return:

a new zlib compressor instance (see zlib_compressor)
Rtype:

userdata

Example

local zlib_compressor = require('compress.zlib').new({
    level = 5,
    mem_level = 5,
    strategy = 'filtered'
})

zlib_compressor

object zlib_compressor

A compressor instance that exposes the API for compressing and decompressing data using the zlib algorithm. To create the zlib compressor, call compress.zlib.new().

zlib_compressor:compress(data)

Compress the specified data.

Параметры:
  • data (string) – data to be compressed
Return:

compressed data
Rtype:

string

Example

compressed_data = zlib_compressor:compress('Hello world!')
zlib_compressor:decompress(data)

Decompress the specified data.

Параметры:
  • data (string) – data to be decompressed
Return:

decompressed data
Rtype:

string

Example

decompressed_data = zlib_compressor:decompress(compressed_data)

zlib_opts

object zlib_opts

Configuration options of the zlib_compressor. These options can be passed to the compress.zlib.new() function.

Example

local zlib_compressor = require('compress.zlib').new({
    level = 5,
    mem_level = 5,
    strategy = 'filtered'
})
zlib_opts.level

Specifies the zlib compression level that enables you to adjust the compression ratio and speed. The lower level improves the compression speed at the cost of compression ratio.

Default: 6
Minimum: 0 (no compression)
Maximum: 9
zlib_opts.mem_level

Specifies how much memory is allocated for the zlib compressor. The larger value improves the compression speed and ratio.

Default: 8
Minimum: 1
Maximum: 9
zlib_opts.strategy

Specifies the compression strategy. The possible values:

  • default - for normal data.
  • huffman_only - forces Huffman encoding only (no string match). The fastest compression algorithm but not very effective in compression for most of the data.
  • filtered - for data produced by a filter or predictor. Filtered data consists mostly of small values with a somewhat random distribution. This compression algorithm is tuned to compress them better.
  • rle - limits match distances to one (run-length encoding). rle is designed to be almost as fast as huffman_only but gives better compression for PNG image data.
  • fixed - prevents the use of dynamic Huffman codes and provides a simpler decoder for special applications.

Submodule compress.zstd

Enterprise Edition

This submodule is a part of the Enterprise Edition.

Overview

The compress.zstd submodule provides the ability to compress and decompress data using the zstd algorithm. You can use the zstd compressor as follows:

  1. Create a compressor instance using the compress.zstd.new() function:

    local zstd_compressor = require('compress.zstd').new()
-- or --
local zstd_compressor = require('compress').zstd.new()

    Optionally, you can pass compression options (zstd_opts) specific for zstd:

    local zstd_compressor = require('compress.zstd').new({
    level = 5
})

  2. To compress the specified data, use the compress() method:

    compressed_data = zstd_compressor:compress('Hello world!')

  3. To decompress data, call decompress():

    decompressed_data = zstd_compressor:decompress(compressed_data)

API Reference

Functions  
compress.zstd.new() Create a zstd compressor instance.
Objects  
zstd_compressor A zstd compressor instance.
zstd_opts Configuration options of the zstd compressor.

compress.zstd.new()

compress.zstd.new([zstd_opts])

Create a zstd compressor instance.

Параметры:
Return:

a new zstd compressor instance (see zstd_compressor)
Rtype:

userdata

Example

local zstd_compressor = require('compress.zstd').new({
    level = 5
})

zstd_compressor

object zstd_compressor

A compressor instance that exposes the API for compressing and decompressing data using the zstd algorithm. To create the zstd compressor, call compress.zstd.new().

zstd_compressor:compress(data)

Compress the specified data.

Параметры:
  • data (string) – data to be compressed
Return:

compressed data
Rtype:

string

Example

compressed_data = zstd_compressor:compress('Hello world!')
zstd_compressor:decompress(data)

Decompress the specified data.

Параметры:
  • data (string) – data to be decompressed
Return:

decompressed data
Rtype:

string

Example

decompressed_data = zstd_compressor:decompress(compressed_data)

zstd_opts

object zstd_opts

Configuration options of the zstd_compressor. These options can be passed to the compress.zstd.new() function.

Example

local zstd_compressor = require('compress.zstd').new({
    level = 5
})
zstd_opts.level

Specifies the zstd compression level that enables you to adjust the compression ratio and speed. The lower level improves the compression speed at the cost of compression ratio. For example, you can use level 1 if speed is most important and level 22 if size is most important.

Default: 3
Minimum: -131072
Maximum: 22

Примечание

Assigning 0 to level resets its value to the default (3).

Submodule compress.lz4

Enterprise Edition

This submodule is a part of the Enterprise Edition.

Overview

The compress.lz4 submodule provides the ability to compress and decompress data using the lz4 algorithm. You can use the lz4 compressor as follows:

  1. Create a compressor instance using the compress.lz4.new() function:

    local lz4_compressor = require('compress.lz4').new()
-- or --
local lz4_compressor = require('compress').lz4.new()

    Optionally, you can pass compression options (lz4_opts) specific for lz4:

    local lz4_compressor = require('compress.lz4').new({
    acceleration = 1000,
    decompress_buffer_size = 2097152
})

  2. To compress the specified data, use the compress() method:

    compressed_data = lz4_compressor:compress('Hello world!')

  3. To decompress data, call decompress():

    decompressed_data = lz4_compressor:decompress(compressed_data)

API Reference

Functions  
compress.lz4.new() Create a lz4 compressor instance.
Objects  
lz4_compressor A lz4 compressor instance.
lz4_opts Configuration options of the lz4 compressor.

compress.lz4.new()

compress.lz4.new([lz4_opts])

Create a lz4 compressor instance.

Параметры:
Return:

a new lz4 compressor instance (see lz4_compressor)
Rtype:

userdata

Example

local lz4_compressor = require('compress.lz4').new({
    acceleration = 1000,
    decompress_buffer_size = 2097152
})

lz4_compressor

object lz4_compressor

A compressor instance that exposes the API for compressing and decompressing data using the lz4 algorithm. To create the lz4 compressor, call compress.lz4.new().

lz4_compressor:compress(data)

Compress the specified data.

Параметры:
  • data (string) – data to be compressed
Return:

compressed data
Rtype:

string

Example

compressed_data = lz4_compressor:compress('Hello world!')
lz4_compressor:decompress(data)

Decompress the specified data.

Параметры:
  • data (string) – data to be decompressed
Return:

decompressed data
Rtype:

string

Example

decompressed_data = lz4_compressor:decompress(compressed_data)

lz4_opts

object lz4_opts

Configuration options of the lz4_compressor. These options can be passed to the compress.lz4.new() function.

Example

local lz4_compressor = require('compress.lz4').new({
    acceleration = 1000,
    decompress_buffer_size = 2097152
})
lz4_opts.acceleration

Specifies the acceleration factor that enables you to adjust the compression ratio and speed. The higher acceleration factor increases the compression speed but decreases the compression ratio.

Default: 1
Maximum: 65537
Minimum: 1
lz4_opts.decompress_buffer_size

Specifies the decompress buffer size (in bytes). If the size of decompressed data is larger than this value, the compressor returns an error on decompression.

Default: 1048576

Module config

Since: 3.0.0

The config module provides the ability to work with an instance’s configuration. For example, you can determine whether the current instance is up and running without errors after applying the cluster’s configuration.

By using the config.storage role, you can set up a Tarantool-based centralized configuration storage and interact with this storage using the config module API.

Loading config

To load the config module, use the require() directive:

local config = require('config')

Then, you can access its API:

config:reload()

API Reference

config API  
config:get() Get a configuration applied to the current or remote instance
config:info() Get the current instance’s state in regard to configuration
config:instance_uri() Get a URI of the current or remote instance
config:instances() List all instances of the cluster
config:reload() Reload the current instance’s configuration
config.storage API  
config.storage.put() Put a value by the specified path
config.storage.get() Get a value stored by the specified path
config.storage.delete() Delete a value stored by the specified path
config.storage.info() Get information about an instance’s connection state
config.storage.txn() Make an atomic request

config API

object config
config:get([param, opts])

Get a configuration applied to the current or remote instance. Note the following differences between getting a configuration for the current and remote instance:

  • For the current instance, get() returns its configuration considering environment variables.
  • For a remote instance, get() only considers a cluster configuration and ignores environment variables.
Параметры:
  • param (string) – a configuration option name
  • opts (table) –

    options to pass. The following options are available:

    • instance (since 3.1.0) – the name of a remote instance whose configuration should be obtained
Return:

an instance configuration

Examples:

The example below shows how to get the full instance configuration:

app:instance001> require('config'):get()
---
- fiber:
    io_collect_interval: null
    too_long_threshold: 0.5
    top:
      enabled: false
  # Other configuration values
  # ...

This example shows how to get an iproto.listen option value:

app:instance001> require('config'):get('iproto.listen')
---
- - uri: 127.0.0.1:3301
...

config.get() can also be used in application code to get the value of a custom configuration option.

config:info([version])

Get the current instance’s state in regard to configuration.

Параметры:
  • version (string) –

    (since 3.1.0) the version of the information that should be returned. The version argument can be one of the following values:

    • v1 (default): the meta field returned by info() includes information about the last loaded configuration
    • v2: the meta field returned by info() includes two fields:
      • the last field includes information about the last loaded configuration
      • the active field includes information for the last successfully applied configuration
Return:

a table containing an instance’s state. The returned state includes the following sections:

  • status – one of the following statuses:
    • ready – the configuration is applied successfully
    • check_warnings – the configuration is applied with warnings
    • check_errors – the configuration cannot be applied due to configuration errors
  • meta – additional configuration information
  • alerts – warnings or errors raised on an attempt to apply the configuration

Below are a few examples demonstrating how the info() output might look.

Example: no configuration warnings or errors

In the example below, an instance’s state is ready and no warnings are shown:

app:instance001> require('config'):info('v2')
---
- status: ready
  meta:
    last: &0 []
    active: *0
  alerts: []
...

Example: configuration warnings

In the example below, the instance’s state is check_warnings. The alerts section informs that privileges to the bands space for sampleuser cannot be granted because the bands space has not been created yet:

app:instance001> require('config'):info('v2')
---
- status: check_warnings
  meta:
    last: &0 []
    active: *0
  alerts:
  - type: warn
    message: box.schema.user.grant("sampleuser", "read,write", "space", "bands") has
      failed because either the object has not been created yet, a database schema
      upgrade has not been performed, or the privilege write has failed (separate
      alert reported)
    timestamp: 2024-07-03T18:09:18.826138+0300
...

This warning is cleared when the bands space is created.

Example: configuration errors

In the example below, the instance’s state is check_errors. The alerts section informs that the log.level configuration option has an incorrect value:

app:instance001> require('config'):info('v2')
---
- status: check_errors
  meta:
    last: []
    active: []
  alerts:
  - type: error
    message: '[cluster_config] log.level: Got 8, but only the following values are
      allowed: 0, fatal, 1, syserror, 2, error, 3, crit, 4, warn, 5, info, 6, verbose,
      7, debug'
    timestamp: 2024-07-03T18:13:19.755454+0300
...

Example: configuration errors (centralized configuration storage)

In this example, the meta field includes information about a centralized storage the instance takes a configuration from:

app:instance001> require('config'):info('v2')
---
- status: check_errors
  meta:
    last:
      etcd:
        mod_revision:
          /myapp/config/all: 5
        revision: 5
    active:
      etcd:
        mod_revision:
          /myapp/config/all: 2
        revision: 4
  alerts:
  - type: error
    message: 'etcd source: invalid config at key "/myapp/config/all": [cluster_config]
      groups.group001.replicasets.replicaset001.instances.instance001.log.level: Got
      8, but only the following values are allowed: 0, fatal, 1, syserror, 2, error,
      3, crit, 4, warn, 5, info, 6, verbose, 7, debug'
    timestamp: 2024-07-03T15:22:06.438275Z
...
config:instance_uri([uri_type, opts])

Since: 3.1.0

Get a URI of the current or remote instance.

Параметры:
  • uri_type (string) –

    a URI type. The following URI types are supported:

  • opts (table) –

    options to pass. The following options are available:

    • instance – the name of a remote instance whose URI should be obtained
Return:

a table representing an instance URI. This table might include the following fields:

  • uri – an instance URI
  • login – a username used to connect to this instance
  • password – a user’s password
  • params – URI parameters used to connect to this instance

Примечание

Note that the resulting URI object can be passed to the connect() function of the net.box module.

Example

The example below shows how to get a URI used to advertise storage-b-003 to other cluster members:

local config = require('config')
config:instance_uri('peer', { instance = 'storage-b-003' })
config:instances()

Since: 3.1.0

List all instances of the cluster.

Return:

a table containing information about instances. The returned table uses instance names as the keys and contains the following information for each instance:

  • instance_name – an instance name
  • replicaset_name – the name of a replica set the instance belongs to
  • group_name – the name of a group the instance belongs to

Example

The example below shows how to use instances() to get the names of all instances in the cluster, create a connection to each instance using the connpool module, and log connection URIs using the log module:

local config = require('config')
local connpool = require('experimental.connpool')
local log = require('log')

for instance_name in pairs(config:instances()) do
    local conn = connpool.connect(instance_name)
    log.info("Connection URI for %q: %s:%s", instance_name, conn.host, conn.port)
end

In this example, the same actions are performed for instances from the specified replica set:

local config = require('config')
local connpool = require('experimental.connpool')
local log = require('log')

for instance_name, def in pairs(config:instances()) do
    if def.replicaset_name == 'storage-b' then
        local conn = connpool.connect(instance_name)
        log.info("Connection URI for %q: %s:%s", instance_name, conn.host, conn.port)
    end
end
config:reload()

Reload the current instance’s configuration. Below are a few use cases when this function can be used:

  • A configuration option value specific to this instance is changed in a cluster’s configuration.
  • A new instance is added to a replica set.
  • A centralized configuration with turned-off configuration reloading is updated. Learn more at Reloading configuration.

config.storage API

The config.storage API allows you to interact with a Tarantool-based centralized configuration storage.

config.storage.put(path, value)

Put a value by the specified path.

Параметры:
  • path (string) – a path to put the value by
  • value (string) – a value to put
Return:

a table containing the following fields:

  • revision: a revision after performing the operation
Rtype:

table

Example:

The example below shows how to read a configuration stored in the source.yaml file using the fio module API and put this configuration by the /myapp/config/all path:

local fio = require('fio')
local cluster_config_handle = fio.open('../../source.yaml')
local cluster_config = cluster_config_handle:read()
local response = config.storage.put('/myapp/config/all', cluster_config)
cluster_config_handle:close()

Example on GitHub: tarantool_config_storage

config.storage.get(path)

Get a value stored by the specified path or prefix.

Параметры:
  • path (string) – a path or prefix to get a value by; prefixes end with /
Return:

a table containing the following fields:

  • data: a table containing the information about the value:
    • path: a path
    • mod_revision: the last revision at which this value was modified
    • value:: a value
  • revision: a revision after performing the operation
Rtype:

table

Examples:

The example below shows how to get a configuration stored by the /myapp/config/all path:

local response = config.storage.get('/myapp/config/all')

This example shows how to get all configurations stored by the /myapp/ prefix:

local response = config.storage.get('/myapp/')

Example on GitHub: tarantool_config_storage

config.storage.delete(path)

Delete a value stored by the specified path or prefix.

Параметры:
  • path (string) – a path or prefix to delete the value by; prefixes end with /
Return:

a table containing the following fields:

  • data: a table containing the information about the value:
    • path: a path
    • mod_revision: the last revision at which this value was modified
    • value:: a value
  • revision: a revision after performing the operation
Rtype:

table

Examples:

The example below shows how to delete a configuration stored by the /myapp/config/all path:

local response = config.storage.delete('/myapp/config/all')

In this example, all configuration are deleted:

local response = config.storage.delete('/')

Example on GitHub: tarantool_config_storage

config.storage.info()

Get information about an instance’s connection state.

Return:

a table containing the following fields:

  • status: a connection status, which can be one of the following:
    • connected: if any instance from the quorum is available to the current instance
    • disconnected: if the current instance doesn’t have a connection with the quorum
Rtype:

table
config.storage.txn(request)

Make an atomic request.

Параметры:
  • request (table) –

    a table containing the following optional fields:

    • predicates: a list of predicates to check. Each predicate is a list that contains:
      {target, operator, value[, path]}
      • target – one of the following string values: revision, mod_revision, value, count
      • operator – a string value: eq, ne, gt, lt, ge, le or its symbolic equivalent, for example, ==, !=, >
      • value – an unsigned or string value to compare
      • path (optional) – a string value: can be a path with the mod_revision and value target or a path/prefix with the count target
    • on_success: a list with operations to execute if all predicates in the list evaluate to true
    • on_failure: a list with operations to execute if any of a predicate evaluates to false
Return:

a table containing the following fields:

  • data: a table containing response data:
    • responses: the list of responses for all operations
    • is_success: a boolean value indicating whether the predicate is evaluated to true
  • revision: a revision after performing the operation
Rtype:

table

Example:

local response = config.storage.txn({
    predicates = { { 'value', '==', 'v0', '/myapp/config/all' } },
    on_success = { { 'put', '/myapp/config/all', 'v1' } },
    on_failure = { { 'get', '/myapp/config/all' } }
})

Example on GitHub: tarantool_config_storage

Submodule experimental.config.utils.schema

Since: 3.2.0

The experimental.config.utils.schema module is used to validate and process parts of cluster configurations that have arbitrary user-defined structures:

The module provides an API to get and set configuration values, filter and transform configuration data, and so on.

Важно

experimental.config.utils.schema is an experimental submodule and is subject to changes.

Getting started with config.utils.schema

As an example, consider an application role that has a single configuration option – an HTTP endpoint address.

roles: [ http_api ]
roles_cfg:
  http_api: 'http://127.0.0.1:8080'

This is how you can use the experimental.config.utils.schema module to process the role configuration:

  1. Load the module:

    local schema = require('experimental.config.utils.schema')

  2. Define a schema – the root object that stores information about the role’s configuration – using schema.new(). The example below shows a schema that includes a single string option:

    local http_api_schema = schema.new('http_api', schema.scalar({ type = 'string' }))

    Learn more in Defining a schema.

  3. Use the validate() method of the schema object to validate configuration values against the schema. In case of a role, call this method inside the role’s validate() function:

    local function validate(cfg)
    http_api_schema:validate(cfg)
end

    Learn more in Validating configuration.

  4. Refer to values of configuration options using the get() method inside the role’s apply() function. Learn more in Getting configuration values.

Defining a schema

A configuration schema stores information about a user-defined configuration structure that can be passed inside an app.cfg or a roles_cfg section. It includes option names, types, hierarchy, and other aspects of a configuration.

To create a schema, use the schema.new() function. It has the following arguments:

Schema nodes

Schema nodes describe the hierarchy of options within a schema. There are two types of schema nodes:

  • Scalar nodes hold a single value of a supported primitive type. For example, a string configuration option of a role is a scalar node in its schema.
  • Composite nodes include multiple values in different forms: records, arrays, or maps.

A node can have annotations – named attributes that enable customization of its behavior, for example, setting a default value.

Scalar nodes

Scalar nodes hold a single value of a primitive type, for example, a string or a number. For the full list of supported scalar types, see Data types.

This configuration has one scalar node of the string type:

roles: [ http_api ]
roles_cfg:
  http_api: 'http://127.0.0.1:8080'

To define a scalar node in a schema, use schema.scalar(). The following schema can be used to process the configuration shown above:

local http_api_schema = schema.new('http_api', schema.scalar({ type = 'string' }))

If a scalar node has a limited set of allowed values, you can also define it with the schema.enum(). Pass the list of allowed values as its argument:

scheme = schema.enum({ 'http', 'https' }),

Примечание

Another way to restrict possible option values is the allowed_values built-in annotation.

Data types

Scalar nodes can have the following data types:

Scalar type Lua type Comment
string string  
number number  
integer number Only integer numbers
boolean boolean true or false
string, number or number, string string or number  
any Arbitrary Lua value May be used to declare an arbitrary value that doesn’t need validation.

Records

Record is a composite node that includes a predefined set of other nodes, scalar or composite. In YAML, a record is represented as a node with nested fields. For example, the following configuration has a record node http_api with three scalar fields:

roles: [ http_api ]
roles_cfg:
  http_api:
    host: '127.0.0.1'
    port: 8080
    scheme: 'http'

To define a record node in a schema, use schema.record(). The following schema describes the configuration above:

local listen_address_schema = schema.new('listen_address', schema.record({
    scheme = schema.enum({ 'http', 'https' }),
    host = schema.scalar({ type = 'string' }),
    port = schema.scalar({ type = 'integer' })
}))

Records are also used to define nested schema nodes of non-primitive types. In the example below, the http_api node includes another record listen_address.

roles: [ http_api ]
roles_cfg:
  http_api:
    listen_address:
      host: '127.0.0.1'
      port: 8080
      scheme: 'http'

The following schema describes this configuration:

local listen_address_schema = schema.new('listen_address', schema.record({
    listen_address = schema.record({
        scheme = schema.enum({ 'http', 'https' }),
        host = schema.scalar({ type = 'string' }),
        port = schema.scalar({ type = 'integer' })
    })
}))

Arrays

Array is a composite node type that includes a collection of items of the same type. The items can be either scalar or composite nodes.

In YAML, array items start with hyphens. For example, the following configuration includes an array named http_api. Each its item is a record with three fields: host, port, and scheme:

roles: [ http-api ]
roles_cfg:
  http-api:
  - host: '127.0.0.1'
    port: 8080
    scheme: 'http'
  - host: '127.0.0.1'
    port: 8443
    scheme: 'https'

To create an array node in a schema, use schema.array(). The following schema describes this configuration:

local listen_address_schema = schema.new('listen_address', schema.array({
    items = schema.record({
        scheme = schema.enum({ 'http', 'https' }),
        host = schema.scalar({ type = 'string' }),
        port = schema.scalar({ type = 'integer' })
    })
}))

There is also the schema.set() function that enables creating arrays with a limited set of allowed items.

Maps

Map is a composite node type that holds an arbitrary number of key-value pairs of predefined types.

In YAML, a map is represented as a node with nested fields. For example, the following configuration has the endpoints node:

roles: [ http_api ]
roles_cfg:
  http_api:
    host: '127.0.0.1'
    port: 8080
    scheme: 'http'
    endpoints:
      user: true
      order: true
      customer: false

To create a map node in a schema, use schema.map(). If this node is declared as a map as shown below, the endpoints section can include any number of options with arbitrary names and boolean values.

local listen_address_schema = schema.new('listen_address', schema.record({
    scheme = schema.enum({ 'http', 'https' }),
    host = schema.scalar({ type = 'string' }),
    port = schema.scalar({ type = 'integer' }),
    endpoints = schema.map({ key = schema.scalar({ type = 'string' }),
                             value = schema.scalar({ type = 'boolean' }) })
}))

Annotations

Node annotations are named attributes that define its various aspects. For example, scalar nodes have a required annotation type that defines the node value type. Other annotations can, for example, set a node’s default value and a validation function, or store arbitrary user-provided data.

Annotations are passed in a table to the node creation function:

scheme = schema.scalar({
    type = 'string',
    allowed_values = { 'http', 'https' },
    default = 'http',
}),

Node annotations fall into three groups:

  • Built-in annotations are handled by the module. These are: type, validate, allowed_values, default and apply_default_if. Note that validate and allowed_values are used for validation only. default and apply_default_if can transform the configuration.
  • User-defined annotations add named node attributes that can be used in the application or role code.
  • Computed annotations allow access to annotations of other nodes throughout the schema.
Built-in annotations

Built-in annotations are interpreted by the module itself. There are the following built-in annotations:

  • type – the node value type. The type must be explicitly specified for scalar nodes, except for those created with schema.enum(). For composite nodes and scalar enums, the corresponding constructors schema.record(), schema.map(), schema.array(), schema.set(), and schema.enum() set the type automatically.
  • allowed_values – (optional) a list of possible node values.
  • validate – (optional) a validation function for the provided node value.
  • default – (optional) a value to use if the option is not specified in the configuration.
  • apply_default_if – (optional) a function that defines when to apply the default value.

Consider the following role configuration:

roles: [ http_api ]
roles_cfg:
  http_api:
    host: '127.0.0.1'
    port: 8080
    scheme: 'http'

The following schema uses built-in annotations default, allowed_values, and validate to define default and allowed option values and validation functions:

local listen_address_schema = schema.new('listen_address', schema.record({
    scheme = schema.scalar({
        type = 'string',
        allowed_values = { 'http', 'https' },
        default = 'http',
    }),
    host = schema.scalar({
        type = 'string',
        validate = validate_host,
        default = '127.0.0.1',
    }),
    port = schema.scalar({
        type = 'integer',
        validate = validate_port,
        default = 8080,
    }),
}))

Validation functions can look as follows:

local function validate_host(host, w)
    local host_pattern = "^(%d+)%.(%d+)%.(%d+)%.(%d+)$"
    if not host:match(host_pattern) then
        w.error("'host' should be a string containing a valid IP address, got %q", host)
    end
end

local function validate_port(port, w)
    if port <= 1 or port >= 65535 then
        w.error("'port' should be between 1 and 65535, got %d", port)
    end
end
User-defined annotations

A schema node can have user-defined annotations with arbitrary names. Such annotations are used to implement custom behavior. You can get their names and values from the schema and use in the role or application code.

Example: the env user-defined annotation is used to provide names of environment variables from which the configuration values can be taken.

local listen_address_schema = schema.new('listen_address', schema.record({
    scheme = schema.enum({ 'http', 'https' }, { env = 'HTTP_SCHEME' }),
    host = schema.scalar({ type = 'string', env = 'HTTP_HOST' }),
    port = schema.scalar({ type = 'integer', env = 'HTTP_PORT' })
}))

See the full sample here: Parsing environment variables.

Computed annotations

Computed annotations enable access from a node to annotations of its ancestor nodes.

In the example below, the listen_address record validation function refers to the protocol annotation of its ancestor node:

local listen_address = schema.record({
    scheme = schema.enum({ 'http', 'https' }),
    host = schema.scalar({ type = 'string' }),
    port = schema.scalar({ type = 'integer' })
}, {
    validate = function(data, w)
        local protocol = w.schema.computed.annotations.protocol
        if protocol == 'iproto' and data.scheme ~= nil then
            w.error("iproto doesn't support 'scheme'")
        end
    end,
})

Примечание

If there are several ancestor nodes with this annotation, its value is taken from the closest one to the current node.

The following schema with listen_address passes the validation:

local http_listen_address_schema = schema.new('http_listen_address', schema.record({
    name = schema.scalar({ type = 'string' }),
    listen_address = listen_address,
}, {
    protocol = 'http',
}))

If this record is added to a schema with protocol = 'iproto', the listen_address validation fails with an error:

local iproto_listen_address_schema = schema.new('iproto_listen_address', schema.record({
    name = schema.scalar({ type = 'string' }),
    listen_address = listen_address,
}, {
    protocol = 'iproto',
}))

User-defined methods

A schema can implement custom logic with methods – user-defined functions that can be called on this schema.

For example, this schema has the format method that returns its fields merged in a URI string:

local listen_address_schema = schema.new(
        "listen_address",
        schema.record(
                {
                    scheme = schema.enum({ "http", "https" }),
                    host = schema.scalar({ type = "string" }),
                    port = schema.scalar({ type = "integer" })
                }
        ),
        {
            methods = {
                format = function(_self, url)
                    return string.format("%s://%s:%d", url.scheme, url.host, url.port)
                end
            }
        }
)

Processing configuration data

Validating configuration

The schema object’s validate() method performs all the necessary checks on the provided configuration. It validates the configuration structure, node types, allowed values, and other aspects of the schema.

When writing roles, call this function inside the role validation function:

local function validate(cfg)
    listen_address_schema:validate(cfg)
end

Getting configuration values

To get configuration values, use the schema object’s get() method. It takes the configuration and the full path to the node as arguments:

local function apply(cfg)
    local scheme = listen_address_schema:get(cfg, 'listen_address.scheme')
    local host = listen_address_schema:get(cfg, 'listen_address.host')
    local port = listen_address_schema:get(cfg, 'listen_address.port')
    log.info("HTTP API endpoint: %s://%s:%d", scheme, host, port)
end

Transforming configuration

The schema object has methods that transform configuration data based on the schema, for example, apply_default(), merge(), set().

The following sample shows how to apply default values from the schema to fill missing configuration fields:

local function apply(cfg)
    local cfg_with_defaults = listen_address_schema:apply_default(cfg)
    local scheme = listen_address_schema:get(cfg_with_defaults, 'scheme')
    local host = listen_address_schema:get(cfg_with_defaults, 'host')
    local port = listen_address_schema:get(cfg_with_defaults, 'port')
    log.info("HTTP API endpoint: %s://%s:%d", scheme, host, port)
end

Parsing environment variables

The schema.fromenv() function allows getting configuration values from environment variables. The example below shows how to do this by adding a user-defined annotation env:

local listen_address_schema = schema.new('listen_address', schema.record({
    scheme = schema.enum({ 'http', 'https' }, { env = 'HTTP_SCHEME' }),
    host = schema.scalar({ type = 'string', env = 'HTTP_HOST' }),
    port = schema.scalar({ type = 'integer', env = 'HTTP_PORT' })
}))

local function collect_env_cfg()
    local res = {}
    for _, w in listen_address_schema:pairs() do
        local env_var = w.schema.env
        if env_var ~= nil then
            local value = schema.fromenv(env_var, os.getenv(env_var), w.schema)
            listen_address_schema:set(res, w.path, value)
        end
    end
    return res
end

The function also uses schema object methods:

  • pairs() to iterate over the schema nodes.
  • set() to assign configuration values.

API Reference

Functions  
schema.array() Create an array node
schema.enum() Create an enum scalar node
schema.fromenv() Parse a value from an environment variable
schema.map() Create a map node
schema.new() Create a schema
schema.record() Create a record node
schema.scalar() Create a scalar node
schema.set() Create a set array node
schema_object  
schema_object:apply_default() Apply default values
schema_object:filter() Filter schema nodes
schema_object:get() Get specified configuration data
schema_object:map() Transform configuration data
schema_object:merge() Merge two configurations
schema_object:pairs() Walk over a configuration
schema_object:set() Set a configuration value
schema_object:validate() Validate a configuration against a schema
schema_object.methods User-defined methods
schema_object.name Schema name
schema_object.schema Schema nodes hierarchy
schema_node_annotation  
allowed_values Allowed node values
apply_default_if Condition to apply defaults
default Default node value
type Value type
validate Validation function
schema_node_object  
schema_node_object.allowed_values Allowed node values
schema_node_object.apply_default_if Condition to apply defaults
schema_node_object.computed Computed annotations
schema_node_object.default Default value
schema_node_object.fields Record node fields
schema_node_object.items Array node items
schema_node_object.type Scalar node type
schema_node_object.validate Validation function

Functions

schema.array(array_def)

Create an array node of a configuration schema.

Параметры:
Return:

the created array node as a table with the following fields:

  • type: array
  • items: a table describing an array item as a schema node
  • annotations, if provided in array_def
Rtype:

table

See also: Arrays

schema.enum(allowed_values, annotations)

A shortcut for creating a string scalar node with a limited set of allowed values.

Параметры:
Return:

the created scalar node as a table with the following fields:

  • type: string
  • allowed_values: allowed node values
  • annotations, if annotations is provided
Rtype:

table

See also: Scalar nodes

schema.fromenv(env_var_name, raw_value, schema_node)

Parse an environment variable as a value of the given schema node. The env_var_name parameter is used only for error messages. The value (raw_value) should be received using os.getenv() or os.environ().

How the raw value is parsed depends on the schema_node type:

  • Scalar:
    • string: return the value as is
    • number or integer: parse the value as a number or an integer
    • string, number: attempt to parse as a number; in case of a failure return the value as is
    • boolean: accept true and false (case-insensitively), or 1 and 0 for true and false values correspondingly
    • any: parse the value as a JSON
  • Map: parse either as JSON (if the raw value starts with {) or as a comma-separated string of key=value pairs: key1=value1,key2=value2
  • Array: parse either as JSON (if the raw value starts with [) or as a comma-separated string of items: item1,item2,item3

Примечание

Parsing records from environment variables is not supported.

Параметры:
Return:

the parsed value
Rtype:

table

See also: Parsing environment variables

schema.map(map_def)

Create a map node of a configuration schema.

Параметры:
Return:

the created map node as a table with the following fields:

  • type: map
  • key: map key type
  • value: map value type
  • annotations, if provided in map_def
Rtype:

table

See also: Maps

schema.new(schema_name, schema_node[, { methods = <...> }])

Create a schema object.

Параметры:
  • schema_name (string) – a name
  • schema_node (table) – a root schema node
  • methods (table) – methods
Return:

a new schema object (see schema_object) as a table with the following fields:

  • name: the schema name
  • schema: a table with schema nodes
  • methods: a table with user-provided methods
Rtype:

table

See also: Getting started with config.utils.schema

schema.record(fields[, annotations])

Create a record node of a configuration schema.

Параметры:
  • fields (table) –

    a table of fields in the following format:

    {
    [<field_name>] = <schema_node_object>,
    <...>
}

    See also: schema_node_object.

  • annotations (table) – annotations (see Annotations)
Return:

the created record node as a table with the following fields:

  • type: record
  • fields: a table describing the record fields
  • annotations, if provided
Rtype:

table

See also: Records

schema.scalar(scalar_def)

Create a scalar node of a configuration schema.

Параметры:
Return:

the created scalar node as a table with the following fields:

  • type: the node type (see Data types)
  • annotations, if provided
Rtype:

table

See also: Scalar nodes

schema.set(allowed_values, annotations)

Shortcut for creating an array node of unique string values from the given list of allowed values.

Параметры:
  • allowed_values (table) – allowed values of array items
  • annotations (table) – annotations (see Annotations)
Return:

the created array node as a table with the following fields:

  • type: array
  • items: a table describing an array item as a schema node
  • validate: an auto-generated validation function that checks that the values don’t repeat
  • annotations, if provided
Rtype:

table

See also: Arrays

schema_object

object schema_object
schema_object:apply_default(data)

Важно

data is assumed to be validated against the given schema.

Apply default values to scalar nodes. The functions takes the default built-in annotation values of the scalar nodes and applies them based on the apply_default_if annotation. If there is no apply_default_if annotation on a node, the default value is also applied.

Примечание

The method works for static defaults. To define a dynamic default value, use the map() method.

Параметры:
  • data (any) – configuration data
Return:

configuration data with applied schema defaults

See also: default, apply_default_if

schema_object:filter(data, f)

Важно

data is assumed to be validated against the given schema.

Filter data based on the schema annotations. The method returns an iterator by configuration nodes for which the given filter function f returns true.

The filter function f receives the following table as the argument:

w = {
    path = <array-like table>,
    schema = <schema node>,
    data = <data at the given path>,
}

The filter function returns a boolean value that is interpreted as «accepted» or «not accepted».

Example:

Calling a function on all schema nodes that have the my_annotation annotation defined:

s:filter(function(w)
    return w.schema.my_annotation ~= nil
end):each(function(w)
    do_something(w.data)
end)
Параметры:
  • data (any) – configuration data
  • f (function) – filter function
Return:

a luafun iterator
schema_object:get(data, path)

Важно

data is assumed to be validated against the given schema.

Get nested configuration values at the given path. The path can be either a dot-separated string (http.scheme) or an array-like table ({ 'http', 'scheme'}).

Example:

local scheme = listen_address_schema:get(cfg, 'listen_address.scheme')
Параметры:
  • data (any) – configuration data
  • path (string/table) –

    path to the target node as:

    • a string in the dot notation
    • an array-like table
Return:

data at the given path

See also: see Getting configuration values

schema_object:map(data, f, f_ctx)

Важно

data is assumed to be validated against the given schema.

Transform data by the given function. The data fields are transformed by the function passed in the second argument (f), while its structure remains unchanged.

The transformation function takes three arguments:

  • data – the configuration data
  • w – walkthrough node with the following fields:
    • w.schema – schema node
    • w.path – the path to the schema node
    • w.error() – a function for printing human-readable error messages
  • ctx – additional context for the transformation function. Can be used to provide values for a specific call.

An example of the transformation function:

local function f(data, w, ctx)
    if w.schema.type == 'string' and data ~= nil then
        return data:gsub('{{ *foo *}}', ctx.foo)
    end
    return data
end

The map() method traverses all fields of the schema records, even if they are nil or box.NULL in the provided configuration. This allows using this method to set computed default values for missing fields. Note that this is not the case for maps and arrays since the schema doesn’t define their fields to traverse.

Параметры:
  • data (any) – configuration data
  • f (function) – transformation function
  • f_ctx (any) – user-provided context for the transformation function
Return:

transformed configuration data
schema_object:merge(data_a, data_b)

Важно

data_a and data_b are assumed to be validated against the given schema.

Merge two configurations. The method merges configurations in a single node hierarchy, preferring the latter in case of a collision.

The following merge rules are used:

  • any present value is preferred over nil and box.NULL

  • box.NULL is preferred over nil

  • for scalar and array nodes, the right-hand value is used

    Примечание

    • Scalars of the any type are merged the same way as other scalars. They are not deeply merged even if they are tables.
    • Arrays are not concatenated. Left hand array items are discarded.

  • records and maps are deeply merged, that is, the merge is performed recursively for their nested nodes

Параметры:
  • data_a (any) – configuration data
  • data_b (any) – configuration data
Return:

merged configuration data
schema_object:pairs()

Walk over the schema and return scalar, array, and map schema nodes

Важно

The method doesn’t return record nodes.

Return:a luafun iterator

Example:

for _, w in schema:pairs() do
    local path = w.path
    local schema = w.schema
    -- <...>
end
schema_object:set(data, path, value)

Важно

data is assumed to be validated against the given schema. value is validated by the method before the assignment.

Set a given value at the given path in a configuration. The path can be either a dot-separated string (http.scheme) or an array-like table ({ 'http', 'scheme'}).

Параметры:
  • data (any) – configuration data
  • path (string/table) –

    path to the target node as:

    • a string in the dot notation
    • an array-like table
  • value (any) – new value
Return:

updated configuration data

Example: see Parsing environment variables

schema_object:validate(data)

Validate data against the schema. If the data doesn’t adhere to the schema, an error is raised.

The method performs the following checks:

  • field type checks: field values are checked against the schema node types
  • allowed values: if a node has the allowed_values annotations of schema nodes, the corresponding data field is checked against the allowed values list
  • validation functions: if a validation function is defined for a node (the validate annotation), it is executed to check that the provided value is valid.
Параметры:
  • data (any) – data

Example: see Annotations and Validating configuration

See also: allowed_values, validate

schema_object.methods

User-defined methods in the schema.

See also: User-defined methods

schema_object.name

Schema name.

schema_object.schema

Schema nodes hierarchy.

See also: schema_node_object

schema_node_annotation

The following elements of tables passed as node constructor arguments are parsed by the modules as built-in annotations:

  • apply_default_if

    A boolean function that defines whether to apply the default value specified using default. If this function returns true on a provided configuration data, the node receives the default value upon the schema_object.apply_default() method call.

    The function takes two arguments:

    • data – the configuration data
    • w – walkthrough node with the following fields:
      • w.schema – schema node
      • w.path – the path to the schema node
      • w.error() – a function for printing human-readable error messages

    See also: schema_object:apply_default()

  • validate

    A function used to validate node data. The function must raise an error to fail the check. The function is called upon the schema_object:validate() function calls.

    The function takes two arguments:

    • data – the configuration data
    • w – walkthrough node with the following fields:
      • w.schema – schema node
      • w.path – the path to the schema node
      • w.error() – a function for printing human-readable error messages

    Example:

    A function that checks that a string is a valid IP address:

    local function validate_host(host, w)
    local host_pattern = "^(%d+)%.(%d+)%.(%d+)%.(%d+)$"
    if not host:match(host_pattern) then
        w.error("'host' should be a string containing a valid IP address, got %q", host)
    end
end

    See also: schema_object:validate()

schema_node_object

object schema_node_object
schema_node_object.allowed_values

A list of values allowed for the node. The values are taken from the allowed_values node annotation.

schema_node_object.apply_default_if

A function to define when to apply the default node value. The value is taken from the apply_default_if annotation.

schema_node_object.computed

computed.annotations stores the node’s computed annotations.

schema_node_object.default

Node’s default value. The value is taken from the default annotation.

schema_node_object.fields

Child nodes for record nodes. See also Records.

schema_node_object.items

Node items for array nodes. See also Arrays

schema_node_object.type

Node type for scalar nodes. See Data types

schema_node_object.validate

Node value validation function. The value is taken from the validate annotation.

Модуль console

Общие сведения

Модуль console позволяет одному экземпляру Tarantool получать доступ к другому экземпляру Tarantool и позволяет одному экземпляру Tarantool начать прослушивание по порту администрирования.

Указатель

Ниже приведен перечень всех функций модуля console.

Имя Назначение
console.connect() Подключение к экземпляру
console.listen() Прослушивание входящих запросов
console.start() Запуск консоли
console.ac() Установка флага автодополнения ввода
console.delimiter() Настройка разделителя
console.get_default_output() Get default output format
console.set_default_output() Set default output format
console.eos() Set or get end-of-output string
console.connect(uri)

Подключение к экземпляру по URI, смена командной строки с „tarantool>“ на „uri>“ и дальнейшая работа в качестве клиента до окончания сессии пользователя или ввода команды control-D.

Функция console.connect позволяет одному экземпляру Tarantool в интерактивном режиме получать доступ к другому экземпляру Tarantool. Последующие запросы на первый взгляд будут обрабатываться локально, но в действительности запросы отправляются на удаленный экземпляр, а локальный экземпляр выступает в виде клиента. После успешного подключения командная строка сменится, и последующие запросы отправляются и выполняются на удаленном экземпляре. Результат выводится на локальный экземпляр. Чтобы вернуться к работе на локальном экземпляре, введите команду control-D.

Если экземпляр Tarantool по URI запрашивает авторизацию, подключение может выглядеть следующим образом: console.connect('admin:secretpassword@distanthost.com:3301').

Нет ограничений по типу вводимых запросов, кроме ограничений по правам на выполняемые запросы – по умолчанию, вход в систему на удаленном экземпляре выполняется от имени пользователя „guest“. Можно разрешить работу на удаленном экземпляре, выдав права: box.schema.user.grant('guest','execute','universe').

Параметры:
  • uri (string) – URI удаленного экземпляра
возвращает:

nil

Возможные ошибки: подключение не будет установлено, если целевой экземпляр Tarantool не был инициирован с помощью box.cfg{listen=...}.

Пример:

tarantool> console = require('console')
---
...
tarantool> console.connect('198.18.44.44:3301')
---
...
198.18.44.44:3301> -- командная строка показывает, что работа идет с удаленным экземпляром
console.listen(uri)

Прослушивание по URI. Основной способ прослушивания на предмет входящих запросов – по строке информации о подключении, или URI, указанному в box.cfg{listen=...}. Другой способ прослушивания – по URI, указанному в console.listen(...). Этот другой способ называется «административным» или просто «по порту администрирования». Такое прослушивание обычно осуществляется по локальному хосту с доменным Unix-сокетом.

Параметры:
  • uri (string) – URI локального экземпляра

«Административный» адрес – это URI для прослушивания. У него нет значения по умолчанию, поэтому следует указать, будет ли подключение производиться по порту администрирования. Параметр выражен URI = Универсальным идентификатором ресурса, например «/tmpdir/unix_domain_socket.sock», или числовым идентификатором TCP-порта. Подключения часто выполняются по telnet. Типичное значение порта: 3313.

Пример:

tarantool> console = require('console')
---
...
tarantool> console.listen('unix/:/tmp/X.sock')
... main/103/console/unix/:/tmp/X I> started
---
- fd: 6
  name:
    host: unix/
    family: AF_UNIX
    type: SOCK_STREAM
    protocol: 0
    port: /tmp/X.sock
...
console.start()

Запуск консоли на текущем интерактивном терминале.

Пример:

console.start() специально используется с файлами инициализации. Как правило, при запуске экземпляра Tarantool с помощью команды tarantool initialization file, консоль не поддерживается. Эту проблему можно решить путем добавления следующих строк в конце файла инициализации:

local console = require('console')
console.start()
console.ac([true|false])

Установка флага автодополнения ввода. Если значение автодополнения = true (правда), и пользователь использует Tarantool в качестве клиента или подключен к Tarantool по console.connect(), то при нажатии клавиши TAB Tarantool будет автоматически дополнять текст по введенной части. По умолчанию, задано значение true.

console.delimiter(marker)

Настройка специального маркера окончания запроса для консоли Tarantool.

По умолчанию, маркер окончания запроса представляет собой символ разрыва строки (перевод строки). Нет необходимости в специальных маркерах, поскольку Tarantool может определить, если многостроковый запрос не завершен (например, если видно, что при объявлении функции еще не задано конечное ключевое слово). Тем не менее, в особых случаях или при вводе многостроковых запросов в более ранних версиях Tarantool, можно изменить маркер окончания запроса. В результате символ разрыва строки не будет означать окончание запроса.

Чтобы вернуться в нормальный режим, введите команду: console.delimiter('')<marker>

Параметры:
  • marker (string) – специальный маркер окончания запроса для консоли Tarantool

Пример:

tarantool> console = require('console'); console.delimiter('!')
---
...
tarantool> function f ()
         > statement_1 = 'a'
         > statement_2 = 'b'
         > end!
---
...
tarantool> console.delimiter('')!
---
...
console.get_default_output()

Return the current default output format. The result will be fmt="yaml", or it will be fmt="lua" if the last set_default_output call was console.set_default_output('lua').

console.set_default_output('yaml'|'lua')

Set the default output format. The possible values are „yaml“ (the default default) or „lua“. The output format can be changed within a session by executing console.eval('\set output yaml|lua'); see the description of output format in the Interactive console section.

console.eos([string])

Set or access the end-of-output string if default output is „lua“. This is the string that appears at the end of output in a response to any Lua request. The default value is ; semicolon. Saying eos() will return the current value. For example, after require('console').eos('!!') responses will end with „!!“.

Модуль crypto

Общие сведения

«Crypto» is short for «Cryptography», which generally refers to the production of a digest value from a function (usually a Cryptographic hash function), applied against a string. Tarantool’s crypto module supports ten types of cryptographic hash functions (AES, DES, DSS, MD4, MD5, MDC2, RIPEMD, SHA-1, SHA-2). Some of the crypto functionality is also present in the Модуль digest module.

Указатель

Ниже приведен перечень всех функций модуля crypto.

Имя Назначение
crypto.cipher.{algorithm}.{cipher_mode}.encrypt() Шифрование строки
crypto.cipher.{algorithm}.{cipher_mode}.decrypt() Расшифрование строки
crypto.digest.{algorithm}() Получение дайджеста
crypto.hmac.{algorithm}() Получение хеш-ключа
crypto.cipher.{aes128|aes192|aes256|des}.{cbc|cfb|ecb|ofb}.encrypt(string, key, initialization_vector)
crypto.cipher.{aes128|aes192|aes256|des}.{cbc|cfb|ecb|ofb}.decrypt(string, key, initialization_vector)

Передача или возврат шифрованного сообщения, полученного из строки, ключа и (необязательно) вектора инициализации. Четыре алгоритма на выбор:

  • aes128 - aes-128 (128-битные двоичные строки с использованием AES)
  • aes192 - aes-192 (192-битные двоичные строки с использованием AES)
  • aes256 - aes-256 (256-битные двоичные строки с использованием AES)
  • des - des (56-битные двоичные строки с использованием DES, хотя использование DES не рекомендуется)

Также доступны четыре режима блочного шифрования на выбор:

  • cbc - Сцепление блоков шифротекста
  • cfb - Обратная связь по шифротексту
  • ecb - Электронная кодовая книга
  • ofb - Обратная связь по выходу

For more information, read the article about Encryption Modes

Пример:

_16byte_iv='1234567890123456'
_16byte_pass='1234567890123456'
e=crypto.cipher.aes128.cbc.encrypt('string', _16byte_pass, _16byte_iv)
crypto.cipher.aes128.cbc.decrypt(e,  _16byte_pass, _16byte_iv)
crypto.digest.{dss|dss1|md4|md5|mdc2|ripemd160}(string)
crypto.digest.{sha1|sha224|sha256|sha384|sha512}(string)

Передача или возврат дайджеста из строки. Выбор из одиннадцати алгоритмов:

  • dss - dss (с использованием DSS)
  • dss1 - dss (с использованием DSS-1)
  • md4 - md4 (128-битные двоичные строки с использованием MD4)
  • md5 - md5 (128-битные двоичные строки с использованием MD5)
  • mdc2 - mdc2 (с использованием MDC2)
  • ripemd160 - ripemd (160-битные двоичные строки с использованием RIPEMD-160)
  • sha1 - sha-1 (160-битные двоичные строки с использованием SHA-1)
  • sha224 - sha-224 (224-битные двоичные строки с использованием SHA-2)
  • sha256 - sha-256 (256-битные двоичные строки с использованием SHA-2)
  • sha384 - sha-384 (384-битные двоичные строки с использованием SHA-2)
  • sha512 - sha-512(512-битные двоичные строки с использованием SHA-2).

Пример:

crypto.digest.md4('string')
crypto.digest.sha512('string')
crypto.hmac.{md4|md5|ripemd160}(key, string)
crypto.hmac.{sha1|sha224|sha256|sha384|sha512}(key, string)

Передача ключа и строки. Результатом будет код аутентификации сообщения HMAC. 8 алгоритмов на выбор:

  • md4 или md4_hex - md4 (128-битные двоичные строки с использованием MD4)
  • md5 или md5_hex - md5 (128-битные двоичные строки с использованием MD5)
  • ripemd160 или ripemd160_hex - ripemd (160-битные двоичные строки с использованием RIPEMD-160)
  • sha1 или sha1_hex - sha-1 (160-битные двоичные строки с использованием SHA-1)
  • sha224 или sha224_hex - sha-224 (224-битные двоичные строки с использованием SHA-2)
  • sha256 или sha256_hex - sha-256 (256-битные двоичные строки с использованием SHA-2)
  • sha384 или sha384_hex - sha-384 (384-битные двоичные строки с использованием SHA-2)
  • sha512 или sha512_hex - sha-512(512-битные двоичные строки с использованием SHA-2).

Пример:

crypto.hmac.md4('key', 'string')
crypto.hmac.md4_hex('key', 'string')

Инкрементальные методы в модуле crypto

Предположим, что вычислен дайджест для строки „A“, затем часть „B“ добавляется в строку, необходим новый дайджест. Новый дайджест можно пересчитать для всей строки „AB“, но быстрее будет взять вычисленный дайджест для „A“ и внести изменения на основании добавленной части „B“. Это называется многошаговым процессом или «инкрементным» хеш-суммированием, которое поддерживает Tarantool поддерживает для всех криптографических функций.

crypto = require('crypto')

-- вывести дайджест 'AB' по aes-192 пошагово, затем с инкрементом
key = 'key/key/key/key/key/key/'
iv =  'iviviviviviviviv'
print(crypto.cipher.aes192.cbc.encrypt('AB', key, iv))
c = crypto.cipher.aes192.cbc.encrypt.new(key)
c:init(nil, iv)
c:update('A')
c:update('B')
print(c:result())
c:free()

-- вывести дайджест 'AB' по sha-256 пошагово, затем с инкрементом
print(crypto.digest.sha256('AB'))
c = crypto.digest.sha256.new()
c:init()
c:update('A')
c:update('B')
print(c:result())
c:free()

Получение одинаковых результатов из модулей digest и crypto

Следующие функции равноценны. Например, функция digest и функция crypto приведут к одному результату.

crypto.cipher.aes256.cbc.encrypt('x',b32,b16)==digest.aes256cbc.encrypt('x',b32,b16)
crypto.digest.md4('string') == digest.md4('string')
crypto.digest.md5('string') == digest.md5('string')
crypto.digest.sha1('string') == digest.sha1('string')
crypto.digest.sha224('string') == digest.sha224('string')
crypto.digest.sha256('string') == digest.sha256('string')
crypto.digest.sha384('string') == digest.sha384('string')
crypto.digest.sha512('string') == digest.sha512('string')

Модуль csv

Общие сведения

Модуль csv обрабатывает записи, форматированные в соответствии с правилами CSV (значения, разделенные запятыми).

По умолчанию, используются следующие правила форматирования:

Параметры, которые можно передать в функции модуля csv:

Указатель

Ниже приведен перечень всех функций модуля csv.

Имя Назначение
csv.load() Загрузка CSV-файла
csv.dump() Преобразование входного значения в строку формата CSV
csv.iterate() Итерация по записям в формате CSV
csv.load(readable[, {options}])

Получение входного значения в формате CSV из readable и возврат таблицы в качестве выходного значения. Обычно readable представляет собой либо строку, либо открытый для чтения файл. Как правило, параметры options не указываются.

Параметры:
  • readable (object) – строка или любой объект с методом read(), форматированный по правилам CSV
  • options (table) – см. выше
возвращает:

загруженное значение
тип возвращаемого значения:
 

таблица

Пример:

В читаемой строке 3 поля, поле №2 содержит запятую и пробел, поэтому следует использовать кавычки:

tarantool> csv = require('csv')
---
...
tarantool> csv.load('a,"b,c ",d')
---
- - - a
    - 'b,c '
    - d
...

В читаемой строке 2-байтный символ = Палочка в кириллице: (Отобразит палочку только в том случае, если кодировка = UTF-8.)

tarantool> csv.load('a\\211\\128b')
---
- - - a\211\128b
...

Точка с запятой вместо запятой в виде символа разделителя:

tarantool> csv.load('a,b;c,d', {delimiter = ';'})
---
- - - a,b
    - c,d
...

Читаемый файл ./file.csv содержит две записи в формате CSV. Объяснение блока fio дается в разделе fio. Исходный CSV-файл и пример соответственно:

tarantool> -- входное значение в файле file.csv:
tarantool> -- a,"b,c ",d
tarantool> -- a\\211\\128b
tarantool> fio = require('fio')
---
...
tarantool> f = fio.open('./file.csv', {'O_RDONLY'})
---
...
tarantool> csv.load(f, {chunk_size = 4096})
---
- - - a
    - 'b,c '
    - d
  - - a\\211\\128b
...
tarantool> f:close()
---
- true
...
csv.dump(csv-table[, options, writable])

Получение входного значения из таблицы csv-table и возврат строки в формате CSV в качестве выходного значения. Или получение входного значения из таблицы csv-table и размещение выходного значения в writable. Обычно параметры options не указываются. Как правило, если указан writable, то это открытый для чтения файл. csv.dump() – это операция, обратная csv.load().

Параметры:
  • csv-table (table) – таблица, которую можно форматировать в соответствии с правилами CSV
  • options (table) – необязательно. См. выше
  • writable (object) – любой объект с методом write()
возвращает:

записанное значение
тип возвращаемого значения:
 

строка, которая записывается в объект writable, если указан

Пример:

В таблице формата CSV 3 поля, поле №2 содержит «,» поэтому результат включает в себя кавычки

tarantool> csv = require('csv')
---
...
tarantool> csv.dump({'a','b,c ','d'})
---
- 'a,"b,c ",d

'
...

Круговое преобразование: из строки в таблицу и обратно в строку

tarantool> csv_table = csv.load('a,b,c')
---
...
tarantool> csv.dump(csv_table)
---
- 'a,b,c

'
...
csv.iterate(input, {options})

Создание Lua-функции с итератором для прохода по записям в формате CSV по одному полю за раз. Настоятельно рекомендуется использовать итератор для большого объема данных (10 мегабайт и более).

Параметры:
  • csv-table (table) – таблица, которую можно форматировать в соответствии с правилами CSV
  • options (table) – см. выше
возвращает:

Lua-функция с итератором
тип возвращаемого значения:
 

функция с итератором

Пример:

csv.iterate() is the low level of csv.load() and csv.dump(). To illustrate that, here is a function which is the same as the csv.load() function, as seen in the Tarantool source code.

tarantool> load = function(readable, opts)
         >   opts = opts or {}
         >   local result = {}
         >   for i, tup in csv.iterate(readable, opts) do
         >     result[i] = tup
         >   end
         >   return result
         > end
---
...
tarantool> load('a,b,c')
---
- - - a
    - b
    - c
...

Module datetime

Since: 2.10.0

The datetime module provides support for the datetime data types. It allows creating the date and time values either via the object interface or via parsing string values conforming to the ISO-8601 standard.

API Reference

Below is a list of datetime functions, properties, and related objects.

Functions  
datetime.new() Create an object of the datetime type from a table of time units
datetime.now() Create an object of the datetime type with the current date and time
datetime.is_datetime() Check whether the specified value is a datetime object
datetime.parse() Convert an input string with the date and time information into a datetime object
datetime.interval.is_interval() Check whether the specified value is an interval object
datetime.interval.new() Create an object of the interval type from a table of time units
Properties  
datetime.TZ A Lua table that maps timezone names and abbreviations to its index and vice-versa.
Methods  
datetime_object:add() Modify an existing datetime object by adding values of the input argument
datetime_object:format() Convert the standard datetime object presentation into a formatted string
datetime_object:set() Update the field values in the existing datetime object
datetime_object:sub() Modify an existing datetime object by subtracting values of the input argument
datetime_object:totable() Convert the information from a datetime object into the table format
interval_object:totable() Convert the information from an interval object into the table format

Functions

datetime.new([{ units }])

Create an object of the datetime type from a table of time units. See the description of units and examples below.

Параметры:
  • units (table) – Table of time units. If an empty table or no arguments are passed, the datetime object with the default values corresponding to Unix Epoch is created: 1970-01-01T00:00:00Z.
Return:

datetime object
Rtype:

cdata

Possible input time units for datetime.new()

Name Description Type Default
nsec (usec, msec) Fractional part of the last second. You can specify either nanoseconds (nsec), or microseconds (usec), or milliseconds (msec). Specifying two of these units simultaneously or all three ones lead to an error. number 0
sec Seconds. Value range: 0 - 60. A leap second is supported, see a section leap second. number 0
min Minutes. Value range: 0 - 59. number 0
hour Hours. Value range: 0 - 23. number 0
day Day number. Value range: 1 - 31. The special value -1 generates the last day of a particular month (see example below). number 1
month Month number. Value range: 1 - 12. number 1
year Year. number 1970
timestamp Timestamp, in seconds. Similar to the Unix timestamp, but can have a fractional part that is converted in nanoseconds in the resulting datetime object. If the fractional part for the last second is set via the nsec, usec, or msec units, the timestamp value should be integer otherwise an error occurs. The timestamp is not allowed if you already set time and/or date via specific units, namely, sec, min, hour, day, month, and year. number 0
tzoffset A time zone offset from UTC, in minutes. Value range: -720 - 840 inclusive. If both tzoffset and tz are specified, tz has the preference and the tzoffset value is ignored. See a section timezone. number 0
tz A time zone name according to the Time Zone Database. See the Time zones section. string

Examples:

tarantool> datetime.new {
            nsec = 123456789,

            sec = 20,
            min = 25,
            hour = 18,

            day = 20,
            month = 8,
            year = 2021,

            tzoffset  = 180
            }
---
- 2021-08-20T18:25:20.123456789+0300
...

tarantool> datetime.new {
            nsec = 123456789,

            sec = 20,
            min = 25,
            hour = 18,

            day = 20,
            month = 8,
            year = 2021,

            tzoffset = 60,
            tz = 'Europe/Moscow'
            }
---
- 2021-08-20T18:25:20.123456789 Europe/Moscow
...

tarantool> datetime.new {
            day = -1,
            month = 2,
            year = 2021,
            }
---
- 2021-02-28T00:00:00Z
...

tarantool> datetime.new {
            timestamp = 1656664205.123,
            tz = 'Europe/Moscow'
            }
---
- 2022-07-01T08:30:05.122999906 Europe/Moscow
...

tarantool> datetime.new {
            nsec = 123,
            timestamp = 1656664205,
            tz = 'Europe/Moscow'
            }
---
- 2022-07-01T08:30:05.000000123 Europe/Moscow
...
datetime.now()

Create an object of the datetime type with the current date and time.

Return:datetime object
Rtype:cdata
datetime.is_datetime([value])

Check whether the specified value is a datetime object.

Параметры:
  • value (any) – the value to check
Return:

true if the specified value is a datetime object; otherwise, false
Rtype:

boolean
datetime.parse('input_string'[, {format, tzoffset}])

Convert an input string with the date and time information into a datetime object. The input string should be formatted according to one of the following standards:

  • ISO 8601
  • RFC 3339
  • extended strftime – see description of the format() for details.

By default fields that are not specified are equal to appropriate values in a Unix time.

Leap second is supported, see a section leap second.

Параметры:
  • input_string (string) – string with the date and time information.
  • format (string) – indicator of the input_string format. Possible values: „iso8601“, „rfc3339“, or strptime-like format string. If no value is set, the default formatting is used ("%F %T %Z"). Note that only a part of possible ISO 8601 and RFC 3339 formats are supported. To parse unsupported formats, you can specify a format string manually using conversion specifications and ordinary characters.
  • tzoffset (number) – time zone offset from UTC, in minutes.
Return:

a datetime_object
Rtype:

cdata
Return:

a number of parsed characters
Rtype:

number

Example:

tarantool> datetime.parse('1970-01-01T00:00:00Z')
---
- 1970-01-01T00:00:00Z
- 20
...

tarantool> t = datetime.parse('1970-01-01T00:00:00', {format = 'iso8601', tzoffset = 180})

tarantool> t
---
- 1970-01-01T00:00:00+0300
...

tarantool> t = datetime.parse('2017-12-27T18:45:32.999999-05:00', {format = 'rfc3339'})

tarantool> t
---
- 2017-12-27T18:45:32.999999-0500
...

tarantool> T = datetime.parse('Thu Jan  1 03:00:00 1970', {format = '%c'})

tarantool> T
---
- 1970-01-01T03:00:00Z
...

tarantool> T = datetime.parse('12/31/2020', {format = '%m/%d/%y'})

tarantool> T
---
- 2020-12-31T00:00:00Z
...

tarantool> T = datetime.parse('1970-01-01T03:00:00.125000000+0300', {format = '%FT%T.%f%z'})

tarantool> T
---
- 1970-01-01T03:00:00.125+0300
...

tarantool> dt = datetime.parse('01:01:01 MSK', {format ='%H:%M:%S %Z'})

---
...

tarantool> dt.year
---
- 1970
...

tarantool> dt.month
---
- 1
...

tarantool> dt.wday
---
- 5
...

tarantool> dt.tz
---
- MSK
...
datetime.interval.is_interval([value])

Since: 3.2.0

Check whether the specified value is an interval object.

Параметры:
  • value (any) – the value to check
Return:

true if the specified value is an interval object; otherwise, false
Rtype:

boolean

Examples:

If a numeric value is passed to is_interval(), it returns false:

tarantool> datetime = require('datetime')
---
...
tarantool> datetime.interval.is_interval(123)
---
- false
...

If an interval object is passed to is_interval(), it returns true:

tarantool> datetime.interval.is_interval(datetime.interval.new())
---
- true
...
datetime.interval.new()

Create an object of the interval type from a table of time units. See description of units and examples below.

Параметры:
  • input (table) – Table with time units and parameters. For all possible time units, the values are not restricted. If an empty table or no arguments are passed, the interval object with the default value 0 seconds is created.
Return:

interval_object
Rtype:

cdata

Possible input time units and parameters for datetime.interval.new()

Name Description Type Default
nsec (usec, msec) Fractional part of the last second. You can specify either nanoseconds (nsec), or microseconds (usec), or milliseconds (msec). Specifying two of these units simultaneously or all three ones lead to an error. number 0
sec Seconds number 0
min Minutes number 0
hour Hours number 0
day Day number number 0
week Week number number 0
month Month number number 0
year Year number 0
adjust Defines how to round days in a month after an arithmetic operation. string „none“

Examples:

tarantool> datetime.interval.new()

---
- 0 seconds
...

tarantool> datetime.interval.new {
            month = 6,
            year = 1
            }
---
- +1 years, 6 months
...

tarantool> datetime.interval.new {
            day = -1
            }
---
- -1 days
...

Properties

TZ

Since: 2.11.0

A Lua table that maps timezone names (like Europe/Moscow) and timezone abbreviations (like MSK) to its index and vice-versa. See the Time zones section.

tarantool> datetime.TZ['Europe/Moscow']
---
- 947
...

tarantool> datetime.TZ[947]
---
- Europe/Moscow
...

Datetime and interval arithmetic

The datetime module enables creating of objects of two types: datetime and interval.

If you need to shift the datetime object values, you can use either the modifier methods, that is, the datetime_object:add() or datetime_object:sub() methods, or apply interval arithmetic using overloaded + (__add) or - (__sub) methods.

datetime_object:add()/datetime_object:sub() modify the current object, but +/- create copy of the object as the operation result.

In the interval operation, each of the interval subcomponents is sequentially calculated starting from the largest (year) to the smallest (nsec):

If the results of the operation exceed the allowed range for any of the components, an exception is raised.

The datetime and interval objects can participate in arithmetic operations:

The matrix of the addition operands eligibility and their result types:

  datetime interval table
datetime unsupported datetime datetime
interval datetime interval interval

The matrix of the subtraction operands eligibility and their result types:

  datetime interval table
datetime interval datetime datetime
interval unsupported interval interval

The subtraction and addition of datetime objects are performed taking tzdata into account tzoffset or tz fields are set:

tarantool> datetime.new({tz='MSK'}) - datetime.new({tz='UTC'})
---
- -180 minutes
...

Datetime and interval comparison

If you need to compare the datetime and interval object values, you can use standard Lua relational operators: ==, ~=, >, <, >=, and <=. These operators use the overloaded __eq, __lt, and __le metamethods to compare values.

Support for relational operators for interval objects has been added since 2.11.0.

Example 1:

tarantool> dt1 = datetime.new({ year = 2010 })
---
...

tarantool> dt2 = datetime.new({ year = 2024 })
---
...

tarantool> dt1 == dt2
---
- false
...

tarantool> dt1 < dt2
---
- true
...

Example 2:

tarantool> iv1 = datetime.interval.new({month = 1})
---
...

tarantool> iv2 = datetime.interval.new({month = 2})
---
...

tarantool> iv1 < iv2
---
- true
...

Leap second

Leap seconds are a periodic one-second adjustment of Coordinated Universal Time(UTC) in order to keep a system’s time of day close to the mean solar time. However, the Earth’s rotation speed varies in response to climatic and geological events, and due to this, UTC leap seconds are irregularly spaced and unpredictable.

Tarantool includes the Time Zone Database that besides the time zone description files also contains a leapseconds file. You can use the Lua module tarantool to get a used version of tzdata.

This section describes how the datetime module supports leap seconds:

Time zones

Full support has been added since 2.11.0.

Tarantool uses the Time Zone Database (also known as the Olson database and supported by IANA) for timezone support. You can use the Lua module tarantool to get a used version of tzdata.

Every datetime object has three fields that represent timezone support: tz, tzoffset, and isdst:

The fields tz and tzoffset can be set in datetime.new(), datetime.parse(), and datetime_object:set(). The arithmetic on datetime objects are performed taking tzdata into account, when tzoffset or tz fields are set, see the Datetime and interval arithmetic section.

Limitations

References

Модуль decimal

The decimal module has functions for working with exact numbers. This is important when numbers are large or even the slightest inaccuracy is unacceptable. For example Lua calculates 0.16666666666667 * 6 with floating-point so the result is 1. But with the decimal module (using decimal.new to convert the number to decimal type) decimal.new('0.16666666666667') * 6 is 1.00000000000002.

To construct a decimal number, bring in the module with require('decimal') and then use decimal.new(n) or any function in the decimal module:

where n can be a string or a non-decimal number or a decimal number. If it is a string or a non-decimal number, Tarantool converts it to a decimal number before working with it. It is best to construct from strings, and to convert back to strings after calculations, because Lua numbers have only 15 digits of precision. Decimal numbers have 38 digits of precision, that is, the total number of digits before and after the decimal point can be 38. Tarantool supports the usual arithmetic and comparison operators + - * / % ^ < > <= >= ~= ==. If an operation has both decimal and non-decimal operands, then the non-decimal operand is converted to decimal before the operation happens.

Use tostring(decimal-number) to convert back to a string.

A decimal operation will fail if overflow happens (when a number is greater than 10^38 - 1 or less than -10^38 - 1). A decimal operation will fail if arithmetic is impossible (such as division by zero or square root of minus 1). A decimal operation will not fail if rounding of post-decimal digits is necessary to get 38-digit precision.

decimal.abs(string-or-number-or-decimal-number)

Returns absolute value of a decimal number. For example if a is -1 then decimal.abs(a) returns 1.

decimal.exp(string-or-number-or-decimal-number)

Returns e raised to the power of a decimal number. For example if a is 1 then decimal.exp(a) returns 2.7182818284590452353602874713526624978. Compare math.exp(1) from the Lua math library, which returns 2.718281828459.

decimal.is_decimal(string-or-number-or-decimal-number)

Returns true if the specified value is a decimal, and false otherwise. For example if a is 123 then decimal.is_decimal(a) returns false. if a is decimal.new(123) then decimal.is_decimal(a) returns true.

decimal.ln(string-or-number-or-decimal-number)

Returns natural logarithm of a decimal number. For example if a is 1 then decimal.ln(a) returns 0.

decimal.log10(string-or-number-or-decimal-number)

Returns base-10 logarithm of a decimal number. For example if a is 100 then decimal.log10(a) returns 2.

decimal.new(string-or-number-or-decimal-number)

Returns the value of the input as a decimal number. For example if a is 1E-1 then decimal.new(a) returns 0.1.

decimal.precision(string-or-number-or-decimal-number)

Returns the number of digits in a decimal number. For example if a is 123.4560 then decimal.precision(a) returns 7.

decimal.rescale(decimal-number, new-scale)

Returns the number after possible rounding or padding. If the number of post-decimal digits is greater than new-scale, then rounding occurs. The rounding rule is: round half away from zero. If the number of post-decimal digits is less than new-scale, then padding of zeros occurs. For example if a is -123.4550 then decimal.rescale(a, 2) returns -123.46, and decimal.rescale(a, 5) returns -123.45500.

decimal.scale(string-or-number-or-decimal-number)

Returns the number of post-decimal digits in a decimal number. For example if a is 123.4560 then decimal.scale(a) returns 4.

decimal.sqrt(string-or-number-or-decimal-number)

Returns the square root of a decimal number. For example if a is 2 then decimal.sqrt(a) returns 1.4142135623730950488016887242096980786.

decimal.trim(decimal-number)

Returns a decimal number after possible removing of trailing post-decimal zeros. For example if a is 2.20200 then decimal.trim(a) returns 2.202.

Модуль digest

Общие сведения

A «digest» is a value which is returned by a function (usually a Cryptographic hash function), applied against a string. Tarantool’s digest module supports several types of cryptographic hash functions ( AES, MD4, MD5, SHA-1, SHA-2, PBKDF2) as well as a checksum function (CRC32), two functions for base64, and two non-cryptographic hash functions (guava, murmur). Some of the digest functionality is also present in the crypto.

Указатель

Ниже приведен перечень всех функций модуля digest.

Имя Назначение
digest.aes256cbc.encrypt() Шифрование строки с использованием AES
digest.aes256cbc.decrypt() Расшифрование строки с использованием AES
digest.md4() Получение дайджеста с помощью MD4
digest.md4_hex() Получение шестнадцатеричного дайджеста с помощью MD4
digest.md5() Получение дайджеста с помощью MD5
digest.md5_hex() Получение шестнадцатеричного дайджеста с помощью MD5
digest.pbkdf2() Получение дайджеста с помощью PBKDF2
digest.sha1() Получение дайджеста с помощью SHA-1
digest.sha1_hex() Получение шестнадцатеричного дайджеста с помощью SHA-1
digest.sha224() Получение 224-битного дайджеста с помощью SHA-2
digest.sha224_hex() Получение 56-байтного шестнадцатеричного дайджеста с помощью SHA-2
digest.sha256() Получение 256-битного дайджеста с помощью SHA-2
digest.sha256_hex() Получение 64-байтного шестнадцатеричного дайджеста с помощью SHA-2
digest.sha384() Получение 384-битного дайджеста с помощью SHA-2
digest.sha384_hex() Получение 96-байтного шестнадцатеричного дайджеста с помощью SHA-2
digest.sha512() Получение 512-битного дайджеста с помощью SHA-2
digest.sha512_hex() Получение 128-байтного шестнадцатеричного дайджеста с помощью SHA-2
digest.base64_encode() Кодирование строки по стандарту Base64
digest.base64_decode() Декодирование строки по стандарту Base64
digest.urandom() Получение массива случайных байтов
digest.crc32() Получение 32-битной контрольной суммы с помощью CRC32
digest.crc32.new() Запуск инкрементного вычисления CRC32
digest.guava() Получение числа с помощью консистентного хеширования
digest.murmur() Получение дайджеста с помощью MurmurHash
digest.murmur.new() Запуск инкрементного вычисления с помощью MurmurHash
digest.aes256cbc.encrypt(string, key, iv)
digest.aes256cbc.decrypt(string, key, iv)

Возврат 256-битной двоичной строки = дайджест, полученный с помощью AES.

digest.md4(string)

Возврат 128-битной двоичной строки = дайджест, полученный с помощью MD4.

digest.md4_hex(string)

Возврат 32-байтной строки = шестнадцатеричное значение дайджеста, вычисленного с помощью MD4.

digest.md5(string)

Возврат 128-битной двоичной строки = дайджест, полученный с помощью MD5.

digest.md5_hex(string)

Возврат 32-байтной строки = шестнадцатеричное значение дайджеста, вычисленного с помощью MD5.

digest.pbkdf2(string, salt[, iterations[, digest-length]])

Возврат двоичной строки = дайджест, полученный с помощью PBKDF2.
Для эффективности шифрования значение параметра количества итераций iterations должно быть как минимум несколько тысяч. Значение параметра digest-length определяет длину полученной двоичной строки.

Примечание

digest.pbkdf2() yields and should not be used in a transaction (between box.begin() and box.commit()/box.rollback()). PBKDF2 is a time-consuming hash algorithm. It runs in a separate coio thread. While calculations are performed, the fiber that calls digest.pbkdf2() yields and another fiber continues working in the tx thread.

digest.sha1(string)

Возврат 160-битной двоичной строки = дайджест, полученный с помощью SHA-1.

digest.sha1_hex(string)

Возврат 40-байтной строки = шестнадцатеричное значение дайджеста, вычисленного с помощью SHA-1.

digest.sha224(string)

Возврат 224-битной двоичной строки = дайджест, полученный с помощью SHA-2.

digest.sha224_hex(string)

Возврат 56-байтной строки = шестнадцатеричное значение дайджеста, вычисленного с помощью SHA-224.

digest.sha256(string)

Возврат 256-битной двоичной строки = дайджест, полученный с помощью SHA-2.

digest.sha256_hex(string)

Возврат 64-байтной строки = шестнадцатеричное значение дайджеста, вычисленного с помощью SHA-256.

digest.sha384(string)

Возврат 384-битной двоичной строки = дайджест, полученный с помощью SHA-2.

digest.sha384_hex(string)

Возврат 96-байтной строки = шестнадцатеричное значение дайджеста, вычисленного с помощью SHA-384.

digest.sha512(string)

Возврат 512-битной двоичной строки = дайджест, полученный с помощью SHA-2.

digest.sha512_hex(string)

Возврат 128-байтной строки = шестнадцатеричное значение дайджеста, вычисленного с помощью SHA-512.

digest.base64_encode()

Возврат кодированного по base64 значения обычной строки.

Возможные опции:

  • nopad – результат не должен включать в себя „=“ для заполнения символами в конце,
  • nowrap – результат не должен включать в себя символ переноса строки для разделения строк после 72 символов,
  • urlsafe – результат не должен включать в себя „=“ или символ переноса строки и может содержать „-„ или „_“ взамен „+“ или „/“ в качестве 62 и 63 символа в схеме.

Значения параметров могут быть true (правда) или false (ложь), по умолчанию используется false.

Пример:

digest.base64_encode(string_variable,{nopad=true})
digest.base64_decode(string)

Возврат обычной строки из кодированного по base64 значения.

digest.urandom(integer)

Возврат массива случайных байтов с длиной = целому числу.

digest.crc32(string)

Возврат 32-битной контрольной суммы с помощью CRC32.

The crc32 and crc32_update functions use the Cyclic Redundancy Check polynomial value: 0x1EDC6F41 / 4812730177. (Other settings are: input = reflected, output = reflected, initial value = 0xFFFFFFFF, final xor value = 0x0.) If it is necessary to be compatible with other checksum functions in other programming languages, ensure that the other functions use the same polynomial value.

Например, в Python установите пакет crcmod и введите команду:

>>> import crcmod
>>> fun = crcmod.mkCrcFun('4812730177')
>>> fun('string')
3304160206L

В Perl установите модуль Digest::CRC и выполните следующий код:

use Digest::CRC;
$d = Digest::CRC->new(width => 32, poly => 0x1EDC6F41, init => 0xFFFFFFFF, refin => 1, refout => 1);
$d->add('string');
print $d->digest;

(ожидается выходное значение: 3304160206).

digest.crc32.new()

Запуск инкрементного вычисления CRC32. См. примечания по инкрементным методам.

digest.guava(state, bucket)

Возврат числа с помощью консистентного хеширования.

The guava function uses the Consistent Hashing algorithm of the Google guava library. The first parameter should be a hash code; the second parameter should be the number of buckets; the returned value will be an integer between 0 and the number of buckets. For example,

tarantool> digest.guava(10863919174838991, 11)
---
- 8
...
digest.murmur(string)

Возврат 32-битной двоичной строки = дайджест, полученный с помощью MurmurHash.

digest.murmur.new(opts)

Запуск инкрементного вычисления с помощью MurmurHash. См. примечания по инкрементным методам. Например:

murmur.new({seed=0})

Инкрементальные методы в модуле digest

Предположим, что вычислен дайджест для строки „A“, затем часть „B“ добавляется в строку, необходим новый дайджест. Новый дайджест можно пересчитать для всей строки „AB“, но быстрее будет взять вычисленный дайджест для „A“ и внести изменения на основании добавленной части „B“. Это называется многошаговым процессом или «инкрементным» хеш-суммированием, которое поддерживает Tarantool поддерживает для crc32 и murmur…

digest = require('digest')

-- вывести дайджест 'AB' по crc32 пошагово, затем с инкрементом
print(digest.crc32('AB'))
c = digest.crc32.new()
c:update('A')
c:update('B')
print(c:result())

-- вывести дайджест 'AB' по murmur hash пошагово, затем с инкрементом
print(digest.murmur('AB'))
m = digest.murmur.new()
m:update('A')
m:update('B')
print(m:result())

Пример

In the following example, the user creates two functions, password_insert() which inserts a SHA-1 digest of the word «^S^e^c^ret Wordpass» into a tuple set, and password_check() which requires input of a password.

tarantool> digest = require('digest')
---
...
tarantool> function password_insert()
         >   box.space.tester:insert{1234, digest.sha1('^S^e^c^ret Wordpass')}
         >   return 'OK'
         > end
---
...
tarantool> function password_check(password)
         >   local t = box.space.tester:select{12345}
         >   if digest.sha1(password) == t[2] then
         >     return 'Password is valid'
         >   else
         >     return 'Password is not valid'
         >   end
         > end
---
...
tarantool> password_insert()
---
- 'OK'
...

Если затем пользователь вызовет функцию password_check() и вводит неверный пароль, результатом будет ошибка.

tarantool> password_check('Secret Password')
---
- 'Password is not valid'
...

Модуль errno

Общие сведения

Модуль errno, как правило, используется внутри функции или в рамках Lua-программы совместно с модулем, функции которого могут возвращать ошибки ОС, например fio.

Указатель

Ниже приведен перечень всех функций модуля errno.

Имя Назначение
errno() Получение номера ошибки для последней функции, связанной с ОС
errno.strerror() Получение сообщения об ошибке для соответствующего номера ошибки
errno()

Возврат номера ошибки для последней функции, связанной с операционной системой, или 0. Чтобы вызвать функцию, просто введите команду errno() без названия модуля.

тип возвращаемого значения:
 целое число
errno.strerror([code])

Возврат строки в ответ на номер ошибки. Строка будет содержать текст традиционного сообщения об ошибке для текущей операционной системы. Если не указан код code, то будет выведено сообщение об ошибке для последней функции, связанной с операционной системой, или 0.

Параметры:
  • code (integer) – номер ошибки в операционной системе
тип возвращаемого значения:
 

строка

Пример:

Данная функция отображает результат вызова fio.open(), который вызывает ошибку 2 (errno.ENOENT). В результат включен номер ошибки, связанная с ним строка сообщения об ошибке и название ошибки.

tarantool> function f()
         >   local fio = require('fio')
         >   local errno = require('errno')
         >   fio.open('no_such_file')
         >   print('errno() = ' .. errno())
         >   print('errno.strerror() = ' .. errno.strerror())
         >   local t = getmetatable(errno).__index
         >   for k, v in pairs(t) do
         >     if v == errno() then
         >       print('errno() constant = ' .. k)
         >     end
         >   end
         > end
---
...

tarantool> f()
errno() = 2
errno.strerror() = No such file or directory
errno() constant = ENOENT
---
...

Чтобы увидеть все возможные названия ошибок, которые хранятся в метатаблице errno, введите команду getmetatable(errno) (выводятся сокращенно):

tarantool> getmetatable(errno)
---
- __newindex: 'function: 0x41666a38'
  __call: 'function: 0x41666890'
  __index:
  ENOLINK: 67
  EMSGSIZE: 90
  EOVERFLOW: 75
  ENOTCONN: 107
  EFAULT: 14
  EOPNOTSUPP: 95
  EEXIST: 17
  ENOSR: 63
  ENOTSOCK: 88
  EDESTADDRREQ: 89
  <...>
...

Module experimental.connpool

Since: 3.1.0

Важно

experimental.connpool is an experimental module and is subject to changes.

The experimental.connpool module provides a set of features for connecting to remote cluster instances and for executing remote procedure calls on an instance that satisfies the specified criteria.

Примечание

Note that the execution time for experimental.connpool functions depends on the number of instances and the time required to connect to each instance.

Loading a module

To load the experimental.connpool module, use the require() directive:

local connpool = require('experimental.connpool')

API Reference

Functions  
connpool.call() Execute the specified function on a remote instance
connpool.connect() Create a connection to the specified instance
connpool.filter() Get names of instances that match the specified conditions

Functions

connpool.call(func_name, args, opts)

Execute the specified function on a remote instance.

Примечание

The function is executed on behalf of the user that maintains replication in the cluster. Ensure that this user has the execute permission for the function to execute.

Параметры:
  • func_name (string) – a name of the function to execute.
  • args (table/nil) – function arguments.
  • opts (table/nil) –

    options used to select candidates on which the function should be executed:

    • labels – the labels an instance has.
    • roles – the roles of an instance.
    • prefer_local – whether to prefer a local or remote instance to execute call() on:
      • if true (default), call() tries to execute the specified function on a local instance.
      • if false, call() tries to connect to a random candidate until a connection is established.
    • mode – a mode that allows filtering candidates based on their read-only status. This option accepts the following values:
      • nil (default) – don’t check the read-only status of instances.
      • ro – consider only read-only instances.
      • rw – consider only read-write instances.
      • prefer_ro – consider read-only instances, then read-write instances.
      • prefer_rw – consider read-write instances, then read-only instances.
    • instances – the names of instances to consider as candidates.
    • replicasets – the names of replica sets whose instances are considered as candidates.
    • groups – the names of groups whose instances are considered as candidates.
    • timeout – a connection timeout (in seconds).
    • buffer – a buffer used to read a returned value.
    • on_push – a function to execute when the client receives an out-of-band message. Learn more from box.session.push().
    • on_push_ctx – an argument of the function executed when the client receives an out-of-band message. Learn more from box.session.push().
    • is_async – whether to wait for the result of the call.
Return:

a function’s return value.

Example

In the example below, the following conditions are specified to choose an instance to execute the vshard.storage.buckets_count function:

  • An instance has the roles.crud-storage role.
  • An instance has the dc label set to east.
  • An instance is read-only.
local connpool = require('experimental.connpool')
local buckets_count = connpool.call('vshard.storage.buckets_count',
        nil,
        { roles = { 'roles.crud-storage' },
          labels = { dc = 'east' },
          mode = 'ro' }
)
connpool.connect(instance_name, opts)

Create a connection to the specified instance.

Параметры:
  • instance_name (string) – an instance name.
  • opts (table/nil) –

    none, any, or all of the following parameters:

    • connect_timeout – a connection timeout (in seconds).
    • wait_connected – whether to block the connection until it is established:
      • if true (default), the connection is blocked until it is established.
      • if false, the connection is returned immediately.
    • fetch_schema – whether to fetch schema changes from a remote instance.
Return:

a net.box connection.

Example

In the example below, connect() is used to create the active connection to storage-b-002:

local connpool = require('experimental.connpool')
local conn = connpool.connect("storage-b-002", { fetch_schema = true })

Once you have a connection, you can execute requests on the remote instance, for example, select data from a space using conn.space.<space-name>:select().

connpool.filter(opts)

Get names of instances that match the specified conditions.

Параметры:
  • opts (table/nil) –

    none, any, or all of the following parameters:

    • labels – the labels an instance has.
    • roles – the roles of an instance.
    • mode – a mode that allows filtering candidates based on their read-only status. This option accepts the following values:
      • nil (default) – don’t check the read-only status of instances.
      • ro – consider only read-only instances.
      • rw – consider only read-write instances.
    • instances – the names of instances to consider as candidates.
    • replicasets – the names of replica sets whose instances are considered as candidates.
    • groups – the names of groups whose instances are considered as candidates.
Return:

an array of instance names.

Example

In the example below, filter() should return a list of instances with the roles.crud-storage role and specified label value:

local connpool = require('experimental.connpool')
local instance_names = connpool.filter({ roles = { 'roles.crud-storage' },
                                         labels = { dc = 'east' } })

Module fiber

Общие сведения

С помощью модуля fiber можно:

Указатель

Ниже приведен перечень всех функций и элементов модуля fiber.

Имя Назначение
Fibers
fiber.create() Создание и запуск файбера
fiber.new() Создание файбера без запуска
fiber.self() Получение объекта файбера
fiber.find() Получение объекта файбера по ID
fiber.sleep() Перевод файбера в режим ожидания
fiber.yield() Передача управления
fiber.status() Получение статуса активного файбера
fiber.info() Получение информации о всех файберах
fiber.top() Возврат таблицы с активными файберами и отображение статистики потребления ресурсов ЦП
fiber.kill() Отмена файбера
fiber.testcancel() Проверка отмены действующего файбера
fiber.set_max_slice() Set the default maximum slice for all fibers
fiber.set_slice() Set a slice for the current fiber execution
fiber.extend_slice() Extend a slice for the current fiber execution
fiber.check_slice() Check whether a slice for the current fiber is over
fiber.time() Получение системного времени в секундах
fiber.time64() Получение системного времени в микросекундах
fiber.clock() Получение монотонного времени в секундах
fiber.clock64() Получение монотонного времени в микросекундах
Fiber object
fiber_object:id() Получение ID файбера
fiber_object:name() Получение имени файбера
fiber_object:name(name) Назначение имени файбера
fiber_object:status() Получение статуса файбера
fiber_object:cancel() Отмена файбера
fiber_object.set_max_slice() Set a fiber’s maximum slice
fiber_object.storage Локальное хранилище в пределах файбера
fiber_object:set_joinable() Создание возможности подключения нового файбера
fiber_object:join() Ожидание статуса „dead“ (недоступен) для файбера
Channels
fiber.channel() Создание канала связи
channel_object:put() Отправка сообщения по каналу связи
channel_object:close() Закрытие канала
channel_object:get() Перехват сообщения из канала
channel_object:is_empty() Проверка пустоты канала
channel_object:count() Подсчет сообщений в канале
channel_object:is_full() Проверка заполненности канала
channel_object:has_readers() Проверка пустого канала на наличие читателей в состоянии ожидания
channel_object:has_writers() Проверка полного канала на наличие писателей в состоянии ожидания
channel_object:is_closed() Проверка закрытия канала
Example A useful example about channels
Condition variables
fiber.cond() Создание условной переменной
cond_object:wait() Перевод файбера в режим ожидания до пробуждения другим файбером
cond_object:signal() Пробуждение отдельного файбера
cond_object:broadcast() Пробуждение всех файберов
Example A useful example about condition variables

Файберы

A fiber is a set of instructions that are executed with cooperative multitasking. The fiber module enables you to create a fiber and associate it with a user-supplied function called a fiber function.

A fiber has the following possible states: running, suspended, ready, or dead. A program with fibers is, at any given time, running only one of its fibers. This running fiber only suspends its execution when it explicitly yields control to another fiber that is ready to execute.

When the fiber function ends, the fiber ends and becomes dead. If required, you can cancel a running or suspended fiber. Another useful capability is limiting a fiber execution time for long-running operations.

Примечание

By default, each transaction in Tarantool is executed in a single fiber on a single thread, sees a consistent database state, and commits all changes atomically.

Create a fiber

To create a fiber, call one of the following functions:

  • fiber.create() creates a fiber and runs it immediately. The initial fiber state is running.
  • fiber.new() creates a fiber but does not start it. The initial fiber state is ready. You can join such fibers by calling the fiber_object:join() function and get the result returned by the fiber’s function.

Передача управления

Yield is an action that occurs in a cooperative environment that transfers control of the thread from the current fiber to another fiber that is ready to execute. The fiber module provides the following functions that yield control to another fiber explicitly:

  • fiber.yield() yields control to the scheduler.
  • fiber.sleep() yields control to the scheduler and sleeps for the specified number of seconds.

Отмена файбера

To cancel a fiber, use the fiber_object.cancel function. You can also call fiber.kill() to locate a fiber by its numeric ID and cancel it.

Limit execution time

If a fiber works too long without yielding control, you can use a fiber slice to limit its execution time. The fiber_slice_default compat option controls the default value of the maximum fiber slice.

There are two slice types: a warning and an error slice.

  • When a warning slice is over, a warning message is logged, for example:

    fiber has not yielded for more than 0.500 seconds

  • When an error slice is over, the fiber is cancelled and the FiberSliceIsExceeded error is thrown:

    FiberSliceIsExceeded: fiber slice is exceeded

    Control is passed to another fiber that is ready to execute.

The fiber slice is checked by all functions operating on spaces and indexes, such as index_object.select(), space_object.replace(), and so on. You can also use the fiber.check_slice() function in application code to check whether the slice for the current fiber is over.

The following functions override the the default value of the maximum fiber slice:

The maximum slice is set when a fiber wakes up. This might be its first run or wake up after fiber.yield().

You can change or increase the slice for a current fiber’s execution using the following functions:

Note that the specified values don’t affect a fiber’s execution after fiber.yield().

Information about fibers

To get information about all fibers or a specific fiber, use the following functions:

Garbage collection

Сборщик мусора собирает недоступные файберы так же, как и все Lua-объекты: сборщик мусора в Lua освобождает память выделенного для файбера пула, сбрасывает все данные файбера и возвращает файбер (который теперь называется каркасом файбера) в пул файберов. Каркас можно использовать повторно при создании другого файбера.

A fiber has all the features of a Lua coroutine and all the programming concepts that apply to Lua coroutines apply to fibers as well. However, Tarantool has made some enhancements for fibers and has used fibers internally. So, although the use of coroutines is possible and supported, the use of fibers is recommended.

API reference

fiber.create(function[, function-arguments])

Создание и запуск файбера. Происходит создание файбера, который незамедлительно начинает работу.

Параметры:
  • function – функция, которая будет связана с файбером
  • function-arguments – arguments to be passed to the function
возвращает:

созданный объект файбера
тип возвращаемого значения:
 

пользовательские данные

Пример:

The script below shows how to create a fiber using fiber.create:

-- app.lua --
fiber = require('fiber')

function greet(name)
    print('Hello, '..name)
end

greet_fiber = fiber.create(greet, 'John')
print('Fiber already started')

The following output should be displayed after running app.lua:

$ tarantool app.lua
Hello, John
Fiber already started
fiber.new(function[, function-arguments])

Create a fiber but do not start it. The created fiber starts after the fiber creator (that is, the job that is calling fiber.new()) yields. The initial fiber state is ready.

Примечание

Note that fiber.status() returns the suspended state for ready fibers because the ready state is not observable using the fiber module API.

You can join fibers created using fiber.new by calling the fiber_object:join() function and get the result returned by the fiber’s function. To join the fiber, you need to make it joinable using fiber_object:set_joinable().

Параметры:
  • function – функция, которая будет связана с файбером
  • function-arguments – arguments to be passed to the function
возвращает:

созданный объект файбера
тип возвращаемого значения:
 

пользовательские данные

Пример:

The script below shows how to create a fiber using fiber.new:

-- app.lua --
fiber = require('fiber')

function greet(name)
    print('Hello, '..name)
end

greet_fiber = fiber.new(greet, 'John')
print('Fiber not started yet')

The following output should be displayed after running app.lua:

$ tarantool app.lua
Fiber not started yet
Hello, John
fiber.self()
возвращает:объект файбера для запланированного на данный момент файбера.
тип возвращаемого значения:
 пользовательские данные

Пример:

tarantool> fiber.self()
---
- status: running
  name: interactive
  id: 101
...
fiber.find(id)
Параметры:
  • id – числовой идентификатор файбера.
возвращает:

объект файбера для указанного файбера.
тип возвращаемого значения:
 

пользовательские данные

Пример:

tarantool> fiber.find(101)
---
- status: running
  name: interactive
  id: 101
...
fiber.sleep(time)

Передача управления планировщику и переход в режим ожидания на указанное количество секунд. Только текущий файбер можно перевести в режим ожидания.

Параметры:
  • time – количество секунд в режиме ожидания.
Исключение:

см. Пример неудачной передачи управления

Пример:

The increment function below contains an infinite loop that adds 1 to the counter global variable. Then, the current fiber goes to sleep for period seconds. sleep causes an implicit fiber.yield().

-- app.lua --
fiber = require('fiber')

counter = 0
function increment(period)
    while true do
        counter = counter + 1
        fiber.sleep(period)
    end
end

increment_fiber = fiber.create(increment, 2)
require('console').start()

After running the script above, print the information about the fiber: a fiber ID, its status, and the counter value.

tarantool> print('ID: ' .. increment_fiber:id() .. '\nStatus: ' .. increment_fiber:status() .. '\nCounter: ' .. counter)
ID: 104
Status: suspended
Counter: 8
---
...

Then, cancel the fiber and print the information about the fiber one more time. This time the fiber status is dead.

tarantool> increment_fiber:cancel()
---
...

tarantool> print('ID: ' .. increment_fiber:id() .. '\nStatus: ' .. increment_fiber:status() .. '\nCounter: ' .. counter)
ID: 104
Status: dead
Counter: 12
---
...
fiber.yield()

Передача управления планировщику. Работает аналогично fiber.sleep(0).

Исключение:см. Пример неудачной передачи управления

Пример:

In the example below, two fibers are associated with the same function. Each fiber yields control after printing a greeting.

-- app.lua --
fiber = require('fiber')

function greet()
    while true do
        print('Enter a name:')
        name = io.read()
        print('Hello, '..name..'. I am fiber '..fiber.id())
        fiber.yield()
    end
end

for i = 1, 2 do
    fiber_object = fiber.create(greet)
    fiber_object:cancel()
end

The output might look as follows:

$ tarantool app.lua
Enter a name:
John
Hello, John. I am fiber 104
Enter a name:
Jane
Hello, Jane. I am fiber 105
fiber.status([fiber_object])

Return the status of the current fiber. If the fiber_object is passed, return the status of the specified fiber.

Параметры:
  • fiber_object – (optional) the fiber object
возвращает:

the status of fiber. One of: dead, suspended, or running.
тип возвращаемого значения:
 

строка

Пример:

tarantool> fiber.status()
---
- running
...
fiber.info({[backtrace/bt]})

Возврат информации о всех файберах.

Параметры:
  • backtrace (boolean) – show backtrace. Default: true. Set to false to show less information (symbol resolving can be expensive).
  • bt (boolean) – same as backtrace, but with lower priority.
возвращает:

number of context switches (csw), backtrace, total memory, used memory, fiber ID (fid), fiber name. If fiber.top is enabled or Tarantool was built with ENABLE_FIBER_TOP, processor time (time) is also returned.
тип возвращаемого значения:
 

таблица

Return values explained

  • csw – number of context switches.
  • backtrace, bt – each fiber’s stack trace, showing where it originated and what functions were called.
  • memory:
    • total – total memory occupied by the fiber as a C structure, its stack, etc.
    • used – actual memory used by the fiber.
  • time – duplicates the «time» entry from fiber.top().cpu for each fiber.
    Only shown if fiber.top is enabled.

Пример:

tarantool> fiber.info({ bt = true })
---
- 101:
    csw: 1
    backtrace:
    - C: '#0  0x5dd130 in lbox_fiber_id+96'
    - C: '#1  0x5dd13d in lbox_fiber_stall+13'
    - L: stall in =[C] at line -1
    - L: (unnamed) in @builtin/fiber.lua at line 59
    - C: '#2  0x66371b in lj_BC_FUNCC+52'
    - C: '#3  0x628f28 in lua_pcall+120'
    - C: '#4  0x5e22a8 in luaT_call+24'
    - C: '#5  0x5dd1a9 in lua_fiber_run_f+89'
    - C: '#6  0x45b011 in fiber_cxx_invoke(int (*)(__va_list_tag*), __va_list_tag*)+17'
    - C: '#7  0x5ff3c0 in fiber_loop+48'
    - C: '#8  0x81ecf4 in coro_init+68'
    memory:
    total: 516472
    used: 0
    time: 0
    name: lua
    fid: 101
  102:
    csw: 0
    backtrace:
    - C: '#0  (nil) in +63'
    - C: '#1  (nil) in +63'
    memory:
    total: 516472
    used: 0
    time: 0
    name: on_shutdown
    fid: 102

...
fiber.top()

Отображение всех активных файберов и потребляемых ими ресурсов ЦП.

возвращает:таблица с двумя записями:cpu и cpu_misses

cpu это ещё одна таблица, в которой ключами являются строки с ID и именами файберов. Для каждого файбера доступны 3 метрики:

  1. instant (in percent), which indicates the share of time the fiber was executing during the previous event loop iteration.

  2. average (in percent), which is calculated as an exponential moving average of instant values over all the previous event loop iterations.

  3. time (в секундах) определяет процессорное время, потраченное на обработку каждого файбера за время его существования.

    Запись time также добавляется к выводу информации о файбере с помощью fiber.info() (дублируется запись time из fiber.top().cpu для каждого файбера).

    Обратите внимание, что подсчет time ведется, только если активна функция fiber.top().

cpu_misses показывает число раз, когда поток TX регистрировал перенос файбера на другое ядро процессора во время последней итерации цикла обработки событий. fiber.top() использует счетчик меток времени для измерения времени выполнения каждого файбера. Однако в разных ядрах могут быть разные значения счетчика, поэтому полагаться на разность показаний счетчика можно только в том случае, если оба измерения были проведены на одном и том же ядре; в противном случае разность показаний может даже быть отрицательной. Когда поток TX переносится на другое ядро процессора, Tarantool просто предполагает, что разность показаний была нулевой для последнего измерения. Это снижает точность вычислений, поэтому больше значение cpu misses, тем ниже точность результатов fiber.top().

Примечание

With 2.11.0, cpu_misses is deprecated and always returns 0.

Пример:

tarantool> fiber.top()
---
- cpu:
    107/lua:
      instant: 30.967324490456
      time: 0.351821993
      average: 25.582738345233
    104/lua:
      instant: 9.6473633128437
      time: 0.110869897
      average: 7.9693406131877
    101/on_shutdown:
      instant: 0
      time: 0
      average: 0
    103/lua:
      instant: 9.8026528631511
      time: 0.112641118
      average: 18.138387232255
    106/lua:
      instant: 20.071174377224
      time: 0.226901357
      average: 17.077908441831
    102/interactive:
      instant: 0
      time: 9.6858e-05
      average: 0
    105/lua:
      instant: 9.2461986412164
      time: 0.10657528
      average: 7.7068458630827
    1/sched:
      instant: 20.265286315108
      time: 0.237095335
      average: 23.141537169257
  cpu_misses: 0
...

Notice that by default new fibers created due to fiber.create are named „lua“ so it is better to set their names explicitly via fiber_object:name(„name“).

There are several system fibers in fiber.top() output that might be useful:

  • sched is a special system fiber. It schedules tasks to other fibers, if any, and also handles some libev events.

    It can have high instant and average values in fiber.top() output in two cases:

    • The instance has almost no load - then practically only sched is executing, and the other fibers are sleeping. So relative to the other fibers, sched may have almost 100% load.
    • sched handles a large number of system events. This should not cause performance problems.

  • main fibers process requests that come over the network (iproto requests). There are several such fibers, and new ones are created if needed. When a new request comes in, a free fiber takes it and executes it. The request can be a typical select/replace/delete/insert or a function call. For example, conn:eval() or conn:call().

Примечание

Enabling fiber.top() slows down fiber switching by about 15%, so it is disabled by default. To enable it, use fiber.top_enable(). To disable it after you finished debugging, use fiber.top_disable().

fiber.kill(id)

Locate a fiber by its numeric ID and cancel it. In other words, fiber.kill() combines fiber.find() and fiber_object:cancel().

Параметры:
  • id – the ID of the fiber to be cancelled.
Исключение:

указанный файбер отсутствует, или отмена невозможна.

Пример:

tarantool> fiber.kill(fiber.id()) -- функция с self может вызвать окончание программы
---
- error: fiber is cancelled
...
fiber.testcancel()

Проверка отмены действующего файбера и выдача исключения, если файбер отменен.

Примечание

Даже при исключении файбер будет отменен. Большинство вызовов проверяют fiber.testcancel(). Однако некоторые функции (id, status, join и т.д.) не вернут ошибку. Мы рекомендуем разработчикам приложений реализовать случайные проверки fiber.testcancel() и максимально быстро завершить выполнение файбера, если он был отменен.

Пример:

tarantool> fiber.testcancel()
---
- error: fiber is cancelled
...
fiber.set_max_slice(slice)

Set the default maximum slice for all fibers. A fiber slice limits the time period of executing a fiber without yielding control.

Параметры:
  • slice (number/table) –

    a fiber slice, which can one of the following:

    • a time period (in seconds) that specifies the error slice. Example: fiber.set_max_slice(3).
    • a table that specifies the warning and error slices (in seconds). Example: fiber.set_max_slice({warn = 1.5, err = 3}).

Пример:

The example below shows how to use set_max_slice to limit the slice for all fibers. fiber.check_slice() is called inside a long-running operation to determine whether a slice for the current fiber is over.

-- app.lua --
fiber = require('fiber')
clock = require('clock')

fiber.set_max_slice({warn = 1.5, err = 3})
time = clock.monotonic()
function long_operation()
    while clock.monotonic() - time < 5 do
        fiber.check_slice()
        -- Long-running operation ⌛⌛⌛ --
    end
end

long_operation_fiber = fiber.create(long_operation)

The output should look as follows:

$ tarantool app.lua
fiber has not yielded for more than 1.500 seconds
FiberSliceIsExceeded: fiber slice is exceeded
fiber.set_slice(slice)

Set a slice for the current fiber execution. A fiber slice limits the time period of executing a fiber without yielding control.

Параметры:
  • slice (number/table) –

    a fiber slice, which can one of the following:

    • a time period (in seconds) that specifies the error slice. Example: fiber.set_slice(3).
    • a table that specifies the warning and error slices (in seconds). Example: fiber.set_slice({warn = 1.5, err = 3}).

Пример:

The example below shows how to use set_slice to limit the slice for the current fiber execution. fiber.check_slice() is called inside a long-running operation to determine whether a slice for the current fiber is over.

-- app.lua --
fiber = require('fiber')
clock = require('clock')

time = clock.monotonic()
function long_operation()
    fiber.set_slice({warn = 1.5, err = 3})
    while clock.monotonic() - time < 5 do
        fiber.check_slice()
        -- Long-running operation ⌛⌛⌛ --
    end
end

long_operation_fiber = fiber.create(long_operation)

The output should look as follows.

$ tarantool app.lua
fiber has not yielded for more than 1.500 seconds
FiberSliceIsExceeded: fiber slice is exceeded
fiber.extend_slice(slice)

Extend a slice for the current fiber execution. For example, if the default error slice is set using fiber.set_max_slice() to 3 seconds, extend_slice(1) extends the error slice to 4 seconds.

Параметры:
  • slice (number/table) –

    a fiber slice, which can one of the following:

    • a time period (in seconds) that specifies the error slice. Example: fiber.extend_slice(1).
    • a table that specifies the warning and error slices (in seconds). Example: fiber.extend_slice({warn = 0.5, err = 1}).

Пример:

The example below shows how to use extend_slice to extend the slice for the current fiber execution. The default fiber slice is set using set_max_slice.

-- app.lua --
fiber = require('fiber')
clock = require('clock')

fiber.set_max_slice({warn = 1.5, err = 3})
time = clock.monotonic()
function long_operation()
    fiber.extend_slice({warn = 0.5, err = 1})
    while clock.monotonic() - time < 5 do
        fiber.check_slice()
        -- Long-running operation ⌛⌛⌛ --
    end
end

long_operation_fiber = fiber.create(long_operation)

The output should look as follows.

$ tarantool app.lua
fiber has not yielded for more than 2.000 seconds
FiberSliceIsExceeded: fiber slice is exceeded

FiberSliceIsExceeded is thrown after 4 seconds.

fiber.check_slice()

Check whether a slice for the current fiber is over. A fiber slice limits the time period of executing a fiber without yielding control.

Пример:

See the examples for the following functions:

fiber.time()
возвращает:текущее системное время (в секундах с начала отсчета) в виде Lua-числа. Время берется из часов событийного цикла, поэтому вызов полезен лишь для создания искусственных ключей кортежа.
тип возвращаемого значения:
 число

Пример:

tarantool> fiber.time(), fiber.time()
---
- 1448466279.2415
- 1448466279.2415
...
fiber.time64()
возвращает:текущее системное время (в микросекундах с начала отсчета) в виде 64-битного целого числа. Время берется из часов событийного цикла.
тип возвращаемого значения:
 cdata (ctype<int64_t>)

Пример:

tarantool> fiber.time(), fiber.time64()
---
- 1448466351.2708
- 1448466351270762
...
fiber.clock()

Получение монотонного времени в секундах. Для вычисления таймаутов лучше использовать fiber.clock(), поскольку fiber.time() сообщает системное время, а оно может меняться при изменениях в системе.

возвращает:количество секунд в виде числа с плавающей точкой, представляющего собой время с некоторого момента в прошлом, которое гарантированно не изменится в течение всего времени процесса
тип возвращаемого значения:
 число

Пример:

tarantool> start = fiber.clock()
---
...
tarantool> print(start)
248700.58805
---
...
tarantool> print(fiber.time(), fiber.time()-start)
1600785979.8291 1600537279.241
---
...
fiber.clock64()

То же, что и fiber.clock(), но в микросекундах.

возвращает:количество секунд в виде 64-битного целого числа, представляющего собой время с некоторого момента в прошлом, которое гарантированно не изменится в течение всего времени процесса
тип возвращаемого значения:
 cdata (ctype<int64_t>)
object fiber_object
fiber_object:id()
Параметры:
  • fiber_object – как правило, это объект, полученный в результате вызова fiber.create, fiber.self или fiber.find
возвращает:

ID of the fiber.
тип возвращаемого значения:
 

число

fiber.self():id() может также быть выражен как fiber.id().

Пример:

tarantool> fiber_object = fiber.self()
---
...
tarantool> fiber_object:id()
---
- 101
...
fiber_object:name()
Параметры:
  • fiber_object – как правило, это объект, полученный в результате вызова fiber.create, fiber.self или fiber.find
возвращает:

имя файбера.
тип возвращаемого значения:
 

строка

fiber.self():name() может также быть выражен как fiber.name().

Пример:

tarantool> fiber.self():name()
---
- interactive
...
fiber_object:name(name[, options])

Change the fiber name. By default a Tarantool server’s interactive-mode fiber is named „interactive“ and new fibers created due to fiber.create are named „lua“. Giving fibers distinct names makes it easier to distinguish them when using fiber.info and fiber.top(). Max length is 255.

Параметры:
  • fiber_object – как правило, это объект, полученный в результате вызова fiber.create, fiber.self или fiber.find
  • name (string) – новое имя файбера.
  • options –
    • truncate=true – truncates the name to the max length if it is too long. If this option is false (the default), fiber.name(new_name) fails with an exception if a new name is too long. The name length limit is 255 (since version 2.4.1).
возвращает:

nil

Пример:

tarantool> fiber.self():name('non-interactive')
---
...
fiber_object:status()

Возврат статуса указанного файбера.

Параметры:
  • fiber_object – как правило, это объект, полученный в результате вызова fiber.create, fiber.self или fiber.find
возвращает:

статус файбера: “dead” (недоступен), “suspended” (приостановлен) или “running” (активен).
тип возвращаемого значения:
 

строка

fiber.self():status() can also be expressed as fiber.status().

Пример:

tarantool> fiber.self():status()
---
- running
...
fiber_object:cancel()

Send a cancellation request to the fiber. Running and suspended fibers can be cancelled. After a fiber has been cancelled, attempts to operate on it cause errors, for example, fiber_object:name() causes error: the fiber is dead. But a dead fiber can still report its ID and status.

Отмена файбера происходит асинхронно. Чтобы дождаться окончания отмены, используйте fiber_object:join(). После вызова fiber_object:cancel() файбер может проверить, был ли он удален. Если он этого не сделает, его отменить невозможно.

Параметры:
  • fiber_object – как правило, это объект, полученный в результате вызова fiber.create, fiber.self или fiber.find
возвращает:

nil

Возможные ошибки: нельзя отменить указанный объект файбера.

Пример:

See the fiber.sleep() example.

fiber_object:set_max_slice(slice)

Set a fiber’s maximum slice. A fiber slice limits the time period of executing a fiber without yielding control.

Параметры:
  • slice (number/table) –

    a fiber slice, which can one of the following:

    • a time period (in seconds) that specifies the error slice. Example: long_operation_fiber.set_max_slice(3).
    • a table that specifies the warning and error slices (in seconds). Example: long_operation_fiber.set_max_slice({warn = 1.5, err = 3}).

Пример:

The example below shows how to use set_max_slice to limit the fiber slice. fiber.check_slice() is called inside a long-running operation to determine whether a slice for the fiber is over.

-- app.lua --
fiber = require('fiber')
clock = require('clock')

time = clock.monotonic()
function long_operation()
    while clock.monotonic() - time < 5 do
        fiber.check_slice()
        -- Long-running operation ⌛⌛⌛ --
    end
end

long_operation_fiber = fiber.new(long_operation)
long_operation_fiber:set_max_slice({warn = 1.5, err = 3})

The output should look as follows.

$ tarantool app.lua
fiber has not yielded for more than 1.500 seconds
FiberSliceIsExceeded: fiber slice is exceeded
fiber_object.storage

A local storage within the fiber. It is a Lua table created when it is first accessed. The storage can contain any number of named values, subject to memory limitations. Naming may be done with fiber_object.storage.name or fiber_object.storage['name']. or with a number fiber_object.storage[number]. Values may be either numbers or strings.

fiber.storage is destroyed when the fiber is finished, regardless of how is it finished – via fiber_object:cancel(), or the fiber’s function did „return“. Moreover, the storage is cleaned up even for pooled fibers used to serve IProto requests. Pooled fibers never really die, but nonetheless their storage is cleaned up after each request. That makes possible to use fiber.storage as a full featured request-local storage. This behavior is implemented in versions 2.2.3, 2.3.2, 2.4.1, and all later versions.

This storage may be created for a fiber, no matter how the fiber itself is created – from C or from Lua. For example, a fiber can be created in C using fiber_new(), then it can insert into a space, which has Lua on_replace triggers, and one of the triggers can create fiber.storage. That storage is deleted when the fiber is stopped.

Пример:

The example below shows how to save the last entered name in a fiber storage and get this value before cancelling a fiber.

-- app.lua --
fiber = require('fiber')

function greet()
    while true do
        print('Enter a name:')
        name = io.read()
        if name ~= 'bye' then
            fiber.self().storage.name = name
            print('Hello, ' .. name)
        else
            print('Goodbye, ' .. fiber.self().storage['name'])
            fiber.self():cancel()
        end
    end
end

fiber_object = fiber.create(greet)

The output might look as follows:

$ tarantool app.lua
Enter a name:
John
Hello, John
Enter a name:
Jane
Hello, Jane
Enter a name:
bye
Goodbye, Jane

См. также box.session.storage.

fiber_object:set_joinable(is_joinable)

Make a fiber joinable. A joinable fiber can be waited for using fiber_object:join().

The best practice is to call fiber_object:set_joinable() before the fiber function begins to execute because otherwise the fiber could become dead before fiber_object:set_joinable() takes effect. The usual sequence could be:

  1. Вызов fiber.new() вместо fiber.create() для создания нового объекта файбера fiber_object.

    Не передавать управление, поскольку это приведет к началу работы функции с файбером.

  2. Вызов fiber_object:set_joinable(true), чтобы сделать новый объект файбера fiber_object присоединяемым.

    Сейчас можно передать управление.

  3. Вызов fiber_object:join().

    Как правило, следует вызвать fiber_object:join(), в противном случае, статус файбера может перейти в „suspended“ (приостановлен) после выполнения функции, а не „dead“ (недоступен).

Параметры:
  • is_joinable (boolean) – the boolean value that specifies whether the fiber is joinable
возвращает:

nil

Пример:

See the fiber_object.join() example.

fiber_object:join([timeout])

Join a fiber. Joining a fiber enables you to get the result returned by the fiber’s function.

Joining a fiber runs the fiber’s function and waits until the fiber’s status is dead. Normally a status becomes dead when the function execution finishes. Joining the fiber causes a yield, therefore, if the fiber is currently in the suspended state, execution of its fiber function resumes.

Note that joining a fiber works only if the fiber is created using fiber.new() and is made joinable using fiber_object:set_joinable().

Параметры:
  • timeout (number) – maximum number of seconds to wait for the completion of the fiber. Default: infinity.
возвращает:

The join method returns two values:

  • The boolean value that indicates whether the join is succeeded because the fiber’s function ended normally.
  • The return value of the fiber’s function.

If the first value is false, then the join succeeded because the fiber’s function ended abnormally and the second result has the details about the error, which one can unpack in the same way that one unpacks a pcall result.
тип возвращаемого значения:
 

boolean + result type, or boolean + struct error

Possible errors: the fiber is already joined by concurrent fiber:join().

Пример:

The example below shows how to get the result returned by the fiber’s function.

fiber = require('fiber')

function add(a, b)
    return a + b
end

add_fiber = fiber.new(add, 5, 6)
add_fiber:set_joinable(true)
is_success, result = add_fiber:join()
print('Is successful: '.. tostring(is_success))
print('Returned value: '..result)

The output should look as follows.

$ tarantool app.lua
Is successful: true
Returned value: 11

Пример неудачной передачи управления

Предупреждение: функция yield() и любая функция, которая неявно передает управление (например, sleep()), может упасть (выдать исключение).

For example, this function has a loop that repeats until cancel() happens. The last thing that it will print is „before yield“, which demonstrates that yield() failed, the loop did not continue until testcancel() failed.

fiber = require('fiber')
function function_name()
  while true do
    print('before testcancel')
    fiber.testcancel()
    print('before yield')
    fiber.yield()
  end
end
fiber_object = fiber.create(function_name)
fiber.sleep(.1)
fiber_object:cancel()

Каналы

Вызов fiber.channel() для создания и получение нового объекта канала.

Вызов других процедур по каналу для отправки сообщений, получения сообщений или проверки статуса канала.

Message exchange is synchronous. The Lua garbage collector will mark or free the channel when no one is using it, as with any other Lua object. Use object-oriented syntax, for example, channel:put(message) rather than fiber.channel.put(message).

fiber.channel([capacity])

Создание нового канала связи.

Параметры:
  • capacity (int) – максимальное количество слотов (спейсы для сообщений channel:put), которые можно использовать одновременно. По умолчанию, 0.
возвращает:

новый объект — канал.
тип возвращаемого значения:
 

userdata. В консоли объект сериализуется и отображается как channel: [число], где [число] — значение, возвращаемое функцией channel_object:count().
object channel_object
channel_object:put(message[, timeout])

Отправка сообщения по каналу связи. Если канал заполнен, channel:put() ожидает, пока не освободится слот в канале.

Примечание

The default channel capacity is 0. With this default value, channel:put() waits infinitely until channel:get() is called.

Параметры:
  • message (lua-value) – то, что отправляется, как правило, строка, число или таблица
  • timeout (number) – максимальное количество секунд ожидания, чтобы слот освободился. Значение по умолчанию: бесконечность.
возвращает:

Если указан параметр времени ожидания timeout, и в канале нет свободного слота в течение указанного времени, возвращается значение false (ложь). Если канал закрыт, возвращается значение false. В остальных случаях возвращается значение true (истина), которое указывает на успешную отправку.
тип возвращаемого значения:
 

boolean (логический)
channel_object:close()

Закрытие канала. Все, кто находится в режиме ожидания в канале, отключаются. Все последующие операции channel:get() вернут нулевое значение nil, а все последующие операции channel:put() вернут false (ложь).

channel_object:get([timeout])

Перехват и удаление сообщения из канала. Если канал пуст, channel:get() будет ожидать сообщения.

Параметры:
  • timeout (number) – максимальное количество секунд ожидания сообщения. Значение по умолчанию: бесконечность.
возвращает:

Если указан параметр времени ожидания timeout, и в канале нет сообщения в течение указанного времени, возвращается нулевое значение nil. Если канал закрыт, возвращается значение nil. В остальных случаях возвращается сообщение, отправленное на канал с помощью channel:put().
тип возвращаемого значения:
 

как правило, строка, число или таблица, как определяет channel:put()
channel_object:is_empty()

Проверка пустоты канала (отсутствие сообщений).

возвращает:true (истина), если канал пуст. В противном случае, false (ложь).
тип возвращаемого значения:
 boolean (логический)
channel_object:count()

Определение количества сообщений в канале.

возвращает:количество сообщений.
тип возвращаемого значения:
 число
channel_object:is_full()

Проверка заполненности канала.

возвращает:true (истина), если канал заполнен (количество сообщений в канале равно количеству слотов, то есть нет места для новых сообщений). В противном случае, false (ложь).
тип возвращаемого значения:
 boolean (логический)
channel_object:has_readers()

Проверка пустого канала на наличие читателей в состоянии ожидания сообщения после отправки запросов channel:get().

возвращает:true (истина), если на канале есть читатели в ожидании сообщения. В противном случае, false (ложь).
тип возвращаемого значения:
 boolean (логический)
channel_object:has_writers()

Проверка полного канала на наличие писателей в состоянии ожидания после отправки запросов channel:put().

возвращает:true (истина), если на канале есть писатели в состоянии ожидании. В противном случае, false (ложь).
тип возвращаемого значения:
 boolean (логический)
channel_object:is_closed()
возвращает:true (истина), если канал уже закрыт. В противном случае, false (ложь).
тип возвращаемого значения:
 boolean (логический)

Пример

В данном примере дается примерное представление о том, как должны выглядеть функции для файберов. Предполагается, что на функции ссылается fiber.create().

fiber = require('fiber')
 channel = fiber.channel(10)
 function consumer_fiber()
     while true do
         local task = channel:get()
         ...
     end
 end

 function consumer2_fiber()
     while true do
         -- 10 секунд
         local task = channel:get(10)
         if task ~= nil then
             ...
         else
             -- время ожидания
         end
     end
 end

 function producer_fiber()
     while true do
         task = box.space...:select{...}
         ...
         if channel:is_empty() then
             -- канал пуст
         end

         if channel:is_full() then
             -- канал полон
         end

         ...
         if channel:has_readers() then
             -- есть файберы
             -- которые ожидают данные
         end
         ...

         if channel:has_writers() then
             -- есть файберы
             -- которые ожидают читателей
         end
         channel:put(task)
     end
 end

 function producer2_fiber()
     while true do
         task = box.space...select{...}
         -- 10 секунд
         if channel:put(task, 10) then
             ...
         else
             -- время ожидания
         end
     end
 end

Условные переменные

Вызов fiber.cond() используется для создания именованной условной переменной, которая будет называться „cond“ для примеров данного раздела.

Вызов cond:wait() используется, чтобы заставить файбер ожидать сигнал, с помощью условной переменной.

Вызов cond:signal() используется, чтобы отправить сигнал для пробуждения отдельного файбера, который выполнил запрос cond:wait().

Вызов cond:broadcast() используется для отправки сигнала всем файберам, которые выполнили cond:wait().

fiber.cond()

Создание новой условной переменной.

возвращает:новая условная переменная.
тип возвращаемого значения:
 Lua-объект
object cond_object
cond_object:wait([timeout])

Перевод файбера в режим ожидания до пробуждения другим файбером с помощью метода signal() или broadcast(). Переход в режим ожидания вызывает неявную передачу управления fiber.yield().

Параметры:
  • timeout – количество секунд ожидания, по умолчанию = всегда.
возвращает:

Если указан параметр времени ожидания timeout, и сигнал не передается в течение указанного времени, wait() вернет значение false (ложь). Если передается signal() или broadcast(), wait() вернет true (истина).
тип возвращаемого значения:
 

boolean (логический)
cond_object:signal()

Пробуждение отдельного файбера, который выполнил wait() для той же переменной. Не выполняет передачу управления (yield).

тип возвращаемого значения:
 nil
cond_object:broadcast()

Пробуждение всех файберов, которые выполнили wait() для той же переменной. Не выполняет передачу управления (yield).

тип возвращаемого значения:
 nil

Пример

Assume that a Tarantool instance is running and listening for connections on localhost port 3301. Assume that guest users have privileges to connect. We will use the tt utility to start two clients.

В первом терминале введите:

$ tt connect localhost:3301
tarantool> fiber = require('fiber')
tarantool> cond = fiber.cond()
tarantool> cond:wait()

Задача повиснет, поскольку cond:wait() – без дополнительного аргумента времени ожидания timeout – уйдет в режим ожидания до изменения условной переменной.

Во втором терминале введите:

$ tt connect localhost:3301
tarantool> cond:signal()

Теперь снова взгляните на терминал №1. Он покажет, что ожидание прекратилось, и функция cond:wait() вернула значение true.

В данном примере показана зависимость от использования глобальной условной переменной с произвольным именем cond. В реальной жизни разработчики следят за использованием различных имен для условных переменных в разных приложениях.

Модуль fio

Общие сведения

Tarantool поддерживает файловый ввод-вывод с помощью API, который аналогичен системным вызовам POSIX. Все операции проводятся асинхронно. Несколько файберов могут получать доступ к одному файлу одновременно.

Модуль fio включает в себя:

Указатель

Ниже приведен перечень всех функций и элементов модуля fio.

Имя Назначение
fio.pathjoin() Формирование пути к файлу из одной или более частей строки
fio.basename() Получение имени файла
fio.dirname() Получение имени директории
fio.abspath() Получение имен директории и файла
fio.path.exists() Проверка наличия файла или директории
fio.path.is_dir() Проверка, является ли файл или директория директорией
fio.path.is_file() Проверка, является ли файл или директория файлом
fio.path.is_link() Проверка, является ли файл или директория ссылкой
fio.path.lexists() Проверка наличия файла или директории
fio.umask() Определение битов маски
fio.lstat()
fio.stat()		 Получение информации об объекте файла
fio.mkdir()
fio.rmdir()		 Создание или удаление директории
fio.chdir() Изменение рабочей директории
fio.listdir() Вывод списка файлов в директории
fio.glob() Получение файлов, имена которых совпадают с заданной строкой
fio.tempdir() Получение имени директории для хранения временных файлов
fio.cwd() Получение имени текущей рабочей директории
fio.copytree()
fio.mktree()
fio.rmtree()		 Создание и удаление директорий
fio.link()
fio.symlink()
fio.readlink()
fio.unlink()		 Создание и удаление ссылок
fio.rename() Переименование файла или директории
fio.utime() Изменение времени обновления файла
fio.copyfile() Копирование файла
fio.chown()
fio.chmod()		 Управление правами на использование и правами владения объектами файла
fio.truncate() Уменьшение размера файла
fio.sync() Проверка записи изменений на диск
fio.open() Открытие файла
file-handle:close() Закрытие файла
file-handle:pread()
file-handle:pwrite()		 Чтение или запись в файл с произвольным доступом
file-handle:read()
file-handle:write()		 Чтение или запись в файл не с произвольным доступом
file-handle:truncate() Изменение размера открытого файла
file-handle:seek() Изменение позиции в файле
file-handle:stat() Получение статистики об открытом файле
file-handle:fsync()
file-handle:fdatasync()		 Проверка записи изменений в открытом файле на диск
fio.c Таблица переменных, аналогичных флаговым значениям POSIX

Стандартные действия с путем к файлу

fio.pathjoin(partial-string[, partial-string ...])

Конкатенация частей строки, разделенных „/“ для формирования пути к файлу.

Параметры:
  • partial-string (string) – одна или более строк для конкатенации.
возвращает:

путь к файлу
тип возвращаемого значения:
 

строка

Пример:

tarantool> fio.pathjoin('/etc', 'default', 'myfile')
---
- /etc/default/myfile
...
fio.basename(path-name[, suffix])

Удаление из полного пути к файлу всего, за исключением последней части (имени файла). Также удаление суффикса, если он передается.

Note that the basename of a path with a trailing slash is an empty string. It is different from how the Unix basename program interprets such a path.

Параметры:
  • path-name (string) – путь к файлу
  • suffix (string) – суффикс
возвращает:

имя файла
тип возвращаемого значения:
 

строка

Пример:

tarantool> fio.basename('/path/to/my.lua', '.lua')
---
- my
...

Example with a trailing slash:

tarantool> fio.basename('/path/to/')
---
-
...
fio.dirname(path-name)

Удаление последней части (имени файла) из полного пути к файлу.

Параметры:
  • path-name (string) – путь к файлу
возвращает:

имя директории, то есть путь к файлу без имени файла.
тип возвращаемого значения:
 

строка

Пример:

tarantool> fio.dirname('/path/to/my.lua')
---
- '/path/to/'
fio.abspath(file-name)

Возврат полного пути к файлу на основании последней части (имени файла).

Параметры:
  • file-name (string) – имя файла
возвращает:

имя директории, то есть путь к файлу с именем файла.
тип возвращаемого значения:
 

строка

Пример:

tarantool> fio.abspath('my.lua')
---
- '/path/to/my.lua'
...

Проверка наличия и типа директории или файла

Functions in this section are similar to some Python os.path functions.

fio.path.exists(path-name)
Параметры:
  • path-name (string) – путь к директории или файлу.
возвращает:

true (правда), если путь к файлу ссылается на директорию или файл, которые присутствуют в системе, и не представляет собой нерабочую символьную ссылку; в противном случае, false (ложь)
тип возвращаемого значения:
 

boolean (логический)
fio.path.is_dir(path-name)
Параметры:
  • path-name (string) – путь к директории или файлу.
возвращает:

true (правда), если путь к файлу ссылается на директорию; в противном случае, false (ложь)
тип возвращаемого значения:
 

boolean (логический)
fio.path.is_file(path-name)
Параметры:
  • path-name (string) – путь к директории или файлу.
возвращает:

true (правда), если путь к файлу ссылается на файл; в противном случае, false (ложь)
тип возвращаемого значения:
 

boolean (логический)
Параметры:
  • path-name (string) – путь к директории или файлу.
возвращает:

true (правда), если путь к файлу ссылается на символьную ссылку; в противном случае, false (ложь)
тип возвращаемого значения:
 

boolean (логический)
fio.path.lexists(path-name)
Параметры:
  • path-name (string) – путь к директории или файлу.
возвращает:

true (правда), если путь к файлу ссылается на директорию или файл, которые присутствуют в системе, и представляет собой нерабочую символьную ссылку; в противном случае, false (ложь)
тип возвращаемого значения:
 

boolean (логический)

Стандартные действия с файлом

fio.umask(mask-bits)

Определение битов маски при создании файлов или директорий. Для получения более подробного описания введите man 2 umask.

Параметры:
  • mask-bits (number) – биты маски.
возвращает:

предыдущие биты маски.
тип возвращаемого значения:
 

число

Пример:

tarantool> fio.umask(tonumber('755', 8))
---
- 493
...
fio.lstat(path-name)
fio.stat(path-name)

Возврат информации об объекте файла. Для получения более подробной информации введите man 2 lstat или man 2 stat.

Параметры:
  • path-name (string) – путь к файлу.
возвращает:

(Если ошибки нет) таблица с полями, которые описывают размер блока файла, время создания, размер и прочие атрибуты.
(В случае ошибки) возвращаются два значения: null, сообщение об ошибке.
тип возвращаемого значения:
 

таблица.

Кроме того, результат fio.stat('имя-файла') будет включать в себя методы, которые аналогичны макросам в POSIX:

  • is_blk() = макрос S_ISBLK в POSIX,
  • is_chr() = макрос S_ISCHR в POSIX
  • is_dir() = макрос S_ISDIR в POSIX,
  • is_fifo() = макрос S_ISFIFO в POSIX,
  • is_link() = макрос S_ISLINK в POSIX,
  • is_reg() = макрос S_ISREG в POSIX,
  • is_sock() = макрос S_ISSOCK в POSIX.

Например, fio.stat('/'):is_dir() вернет true.

Пример:

tarantool> fio.lstat('/etc')
---
- inode: 1048577
  rdev: 0
  size: 12288
  atime: 1421340698
  mode: 16877
  mtime: 1424615337
  nlink: 160
  uid: 0
  blksize: 4096
  gid: 0
  ctime: 1424615337
  dev: 2049
  blocks: 24
...
fio.mkdir(path-name[, mode])
fio.rmdir(path-name)

Создание или удаление директории. Для получения подробной информации введите man 2 mkdir или man 2 rmdir.

Параметры:
  • path-name (string) – путь к директории.
  • mode (number) – Биты режима работы можно передать в виде числа или строковых постоянных, например S_IWUSR. Биты режима работы можно комбинировать путем обрамления их в фигурные скобки.
возвращает:

(Если ошибки нет) true.
(В случае ошибки) возвращаются два значения: false, сообщение об ошибке.
тип возвращаемого значения:
 

boolean (логический)

Пример:

tarantool> fio.mkdir('/etc')
---
- false
...
fio.chdir(path-name)

Изменение рабочей директории. Для получения более подробной информации введите man 2 chdir.

Параметры:
  • path-name (string) – путь к директории.
возвращает:

(Если выполнено) true. (Если не выполнено) false.
тип возвращаемого значения:
 

boolean (логический)

Пример:

tarantool> fio.chdir('/etc')
---
- true
...
fio.listdir(path-name)

Вывод списка файлов в директории. Результат аналогичен результату выполнения команды ls в терминале.

Параметры:
  • path-name (string) – путь к директории.
возвращает:

(Если ошибки нет) список файлов.
(В случае ошибки) возвращаются два значения: null, сообщение об ошибке.
тип возвращаемого значения:
 

таблица

Пример:

tarantool> fio.listdir('/usr/lib/tarantool')
---
- - mysql
...
fio.glob(path-name)

Возврат списка файлов, имена которых совпадают с введенной строкой. Список составляется с одним флагом, который контролирует поведение функции: GLOB_NOESCAPE. Для получения подробной информации введите man 3 glob.

Параметры:
  • path-name (string) – путь к файлу, который может содержать специальные символы.
возвращает:

список файлов, имена которых совпадают с введенной строкой.
тип возвращаемого значения:
 

таблица

Возможные ошибки: nil.

Пример:

tarantool> fio.glob('/etc/x*')
---
- - /etc/xdg
  - /etc/xml
  - /etc/xul-ext
...
fio.tempdir()

Возврат имени директории, которую можно использовать для хранения временных файлов.

Пример:

tarantool> fio.tempdir()
---
- /tmp/lG31e7
...

fio.tempdir() stores the created temporary directory into /tmp by default. Since version 2.4.1, this can be changed by setting the TMPDIR environment variable. Before starting Tarantool, or at runtime by os.setenv().

Пример:

tarantool> fio.tempdir()
---
- /tmp/lG31e7
...
tarantool> fio.mkdir('./mytmp')
---
- true
...

tarantool> os.setenv('TMPDIR', './mytmp')
---
...

tarantool> fio.tempdir()
---
- ./mytmp/506Z0b
...
fio.cwd()

Возврат имени текущей рабочей директории.

Пример:

tarantool> fio.cwd()
---
- /home/username/tarantool_sandbox
...
fio.copytree(from-path, to-path)

Копирование всего из директории from-path, включая поддиректории, в to-path. Результат аналогичен результату выполнения команды cp -r в терминале. Директория to-path не должна быть пустой.

Параметры:
  • from-path (string) – путь.
  • to-path (string) – путь.
возвращает:

(Если ошибки нет) true.
(В случае ошибки) возвращаются два значения: false, сообщение об ошибке.
тип возвращаемого значения:
 

boolean (логический)

Пример:

tarantool> fio.copytree('/home/original','/home/archives')
---
- true
...
fio.mktree(path-name)

Создание пути, включая поддиректории, но без содержимого файла. Результат аналогичен результату выполнения команды mkdir -p в терминале.

Параметры:
  • path-name (string) – путь.
возвращает:

(Если ошибки нет) true.
(В случае ошибки) возвращаются два значения: false, сообщение об ошибке.
тип возвращаемого значения:
 

boolean (логический)

Пример:

tarantool> fio.mktree('/home/archives')
---
- true
...
fio.rmtree(path-name)

Удаление указанной директории, включая поддиректории. Результат аналогичен результату выполнения команды rm -rf в терминале.

Параметры:
  • path-name (string) – путь.
возвращает:

(Если ошибки нет) true.
(В случае ошибки) возвращаются два значения: null, сообщение об ошибке.
тип возвращаемого значения:
 

boolean (логический)

Пример:

tarantool> fio.rmtree('/home/archives')
---
- true
...

Функции для создания и удаления ссылок. Для получения подробной информации введите man readlink, man 2 link, man 2 symlink, man 2 unlink.

Параметры:
  • src (string) – имя существующего файла.
  • dst (string) – связанное имя.
возвращает:

(Если ошибки нет) fio.link, fio.symlink и fio.unlink возвращают true (правда), fio.readlink возвращает ссылку.
(В случае ошибки) возвращаются два значения: false|null, сообщение об ошибке.

Пример:

tarantool> fio.link('/home/username/tmp.txt', '/home/username/tmp.txt2')
---
- true
...
tarantool> fio.unlink('/home/username/tmp.txt2')
---
- true
...
fio.rename(path-name, new-path-name)

Переименование файла или директории. Для получения подробной информации введите man 2 rename.

Параметры:
  • path-name (string) – первоначальное имя.
  • new-path-name (string) – новое имя.
возвращает:

(Если ошибки нет) true.
(В случае ошибки) возвращаются два значения: false, сообщение об ошибке.
тип возвращаемого значения:
 

boolean (логический)

Пример:

tarantool> fio.rename('/home/username/tmp.txt', '/home/username/tmp.txt2')
---
- true
...
fio.utime(file-name[, accesstime[, updatetime]])

Change the access time and possibly also change the update time of a file. For details type man 2 utime. Times should be expressed as number of seconds since the epoch.

Параметры:
  • file-name (string) – имя.
  • accesstime (number) – time of last access. default current time.
  • updatetime (number) – time of last update. default = access time.
возвращает:

(Если ошибки нет) true.
(В случае ошибки) возвращаются два значения: false, сообщение об ошибке.
тип возвращаемого значения:
 

boolean (логический)

Пример:

tarantool> fio.utime('/home/username/tmp.txt')
---
- true
...
fio.copyfile(path-name, new-path-name)

Копирование файла. Результат аналогичен результату выполнения команды cp в терминале.

Параметры:
  • path-name (string) – путь к первоначальному файлу.
  • new-path-name (string) – путь к новому файлу.
возвращает:

(Если ошибки нет) true.
(В случае ошибки) возвращаются два значения: false, сообщение об ошибке.
тип возвращаемого значения:
 

boolean (логический)

Пример:

tarantool> fio.copyfile('/home/user/tmp.txt', '/home/usern/tmp.txt2')
---
- true
...
fio.chown(path-name, owner-user, owner-group)
fio.chmod(path-name, new-rights)

Управление правами на использование и правами владения объектами файла. Для получения подробной информации введите man 2 chown или man 2 chmod.

Параметры:
  • owner-user (string) – новый UID пользователя.
  • owner-group (string) – новый UID группы.
  • new-rights (number) – новые права
возвращает:

null

Пример:

tarantool> fio.chmod('/home/username/tmp.txt', tonumber('0755', 8))
---
- true
...
tarantool> fio.chown('/home/username/tmp.txt', 'username', 'username')
---
- true
...
fio.truncate(path-name, new-size)

Уменьшение размера файла до указанного значения. Для получения подробной информации введите man 2 truncate.

Параметры:
  • path-name (string) –
  • new-size (number) –
возвращает:

(Если ошибки нет) true.
(В случае ошибки) возвращаются два значения: false, сообщение об ошибке.
тип возвращаемого значения:
 

boolean (логический)

Пример:

tarantool> fio.truncate('/home/username/tmp.txt', 99999)
---
- true
...
fio.sync()

Проверка записи изменений на диск. Для получения подробной информации введите man 2 sync.

возвращает:true – если выполнено, false – если не выполнено.
тип возвращаемого значения:
 boolean (логический)

Пример:

tarantool> fio.sync()
---
- true
...
fio.open(path-name[, flags[, mode]])

Открытие файла в процессе подготовки к чтению, записи или поиску.

Параметры:
  • path-name (string) – Полный путь к открываемому файлу.
  • flags (number) –

    Флаги могут передаваться в виде числа или в виде строковых постоянных, например „O_RDONLY“, „O_WRONLY“, „O_RDWR“. Флаги можно комбинировать путем обрамления их в фигурные скобки. Все флаги в Linux, как описано на странице руководства по Linux, представлены ниже:

    • O_APPEND (открывать файл в режиме добавления),
    • O_ASYNC (включать ввод-вывод, управляемый сигналом),
    • O_CLOEXEC (устанавливать флаг, связанный с закрытием),
    • O_CREAT (создать файл, если он не существует),
    • O_DIRECT (минимизировать или отключать кэширование),
    • O_DIRECTORY (завершать вызов с ошибкой, если путь не является директорией),
    • O_EXCL (завершать вызов с ошибкой, если файл не может быть создан),
    • O_LARGEFILE (открывать 64-битные файлы),
    • O_NOATIME (не обновлять время последнего доступа к файлу),
    • O_NOCTTY (не делать терминальное устройство управляющим терминалом tty),
    • O_NOFOLLOW (не открывать символьные ссылки),
    • O_NONBLOCK (открывать в неблокирующем режиме),
    • O_PATH (получить путь для низкоуровневого использования),
    • O_SYNC (включить принудительную запись, если возможно),
    • O_TMPFILE (создать безымянный временный файл),
    • O_TRUNC (урезать)

    … и всегда используется один из флагов:

    • O_RDONLY (только для чтения),
    • O_WRONLY (только для записи) или
    • O_RDWR (для чтения и записи).
  • mode (number) – Биты режима работы можно передать в виде числа или строковых постоянных, например S_IWUSR. Биты режима работы имеют значение, если указаны флаги O_CREAT или O_TMPFILE. Биты режима работы можно комбинировать путем обрамления их в фигурные скобки.
возвращает:

(Если ошибки нет) дескриптор файла (далее сокращенно „fh“).
(В случае ошибки) возвращаются два значения: null, сообщение об ошибке.
тип возвращаемого значения:
 

пользовательские данные

Возможные ошибки: nil.

Note that since version 2.4.1 fio.open() returns a descriptor which can be closed manually by calling the :close() method, or it will be closed automatically when it has no references, and the garbage collector deletes it.

Имейте в виду, что количество файловых дескрипторов ограничено и они могут быть исчерпаны раньше, чем будет запущен сборщик мусора для сбора неиспользуемых дескрипторов. Всегда рекомендуется закрывать их вручную как можно скорее.

Пример 1:

tarantool> fh = fio.open('/home/username/tmp.txt', {'O_RDWR', 'O_APPEND'})
---
...
tarantool> fh -- отображение дескриптора файла, который возвращает fio.open
---
- fh: 11
...

Пример 2:

Using fio.open() with tonumber('N', 8) to set permissions as an octal number:

tarantool> fio.open('x.txt', {'O_WRONLY', 'O_CREAT'}, tonumber('644',8))
 ---
 - fh: 12
 ...
object file-handle
file-handle:close()

Закрытие файла, который был открыт с помощью fio.open. Для получения подробной информации введите man 2 close.

Параметры:
  • fh (userdata) – дескриптор файла, который возвращает fio.open().
возвращает:

true – если выполнено, false – если не выполнено.
тип возвращаемого значения:
 

boolean (логический)

Пример:

tarantool> fh:close() -- где fh = дескриптор файла
---
- true
...
file-handle:pread(count, offset)
file-handle:pread(buffer, count, offset)

Чтение файла с произвольным доступом независимо от текущего положения в поиске. Для получения подробной информации введите man 2 pread.

Параметры:
  • fh (userdata) – дескриптор файла, который возвращает fio.open().
  • buffer – куда считать (если формат – pread(buffer, count, offset))
  • count (number) – количество байтов для чтения
  • offset (number) – смещение в файле – где начинается чтение

Если формат – pread(count, offset), возвращается строка с данными, прочитанными из файла, либо пустая строка, если не выполнено.

Если формат – pread(buffer, count, offset), возвращаются данные в буфер. Буферы можно ввести с помощью buffer.ibuf.

Пример:

tarantool> fh:pread(25, 25)
---
- |
  elete from t8//
  insert in
...
file-handle:pwrite(new-string, offset)
file-handle:pwrite(buffer, count, offset)

Запись в файл с произвольным доступом независимо от текущего положения в поиске. Для получения подробной информации введите man 2 pwrite.

Параметры:
  • fh (userdata) – дескриптор файла, который возвращает fio.open().
  • new-string (string) – записываемое значение (если формат – pwrite(new-string, offset))
  • buffer (cdata) – записываемое значение (если формат – pwrite(buffer, count, offset))
  • count (number) – количество байтов для чтения
  • offset (number) – смещение в файле – где начинается запись
возвращает:

true – если выполнено, false – если не выполнено.
тип возвращаемого значения:
 

boolean (логический)

Если формат –pwrite(new-string, offset), строка записывается в файл до конца строки.

Если формат – pwrite(buffer, count, offset), содержимое буфера записывается в файл в объеме, указанном в count. Буферы можно ввести с помощью buffer.ibuf.

tarantool> ibuf = require('buffer').ibuf()
---
...

tarantool> fh:pwrite(ibuf, 1, 0)
---
- true
...
file-handle:read([count])
file-handle:read(buffer, count)

Чтение файла не с произвольным доступом. Для получения подробной информации введите man 2 read или man 2 write.

Примечание

fh:read и fh:write влияют на положение поиска по файлу, и это следует учитывать при работе нескольких файберов над одним файлом. Существует возможность ограничения или запрета на доступ к файлу с помощью fiber.ipc. Можно ограничить или запретить доступ к файлам из других файберов с помощью fiber.cond() или fiber.channel().

Параметры:
  • fh (userdata) – дескриптор файла, который возвращает fio.open().
  • buffer – куда считать (если формат – read(buffer, count))
  • count (number) – количество байтов для чтения
возвращает:
  • Если формат – read() – без count – считываются все байты в файле.
  • Если формат – read() или read([count]), возвращается строка с данными, прочитанными из файла, либо пустая строка, если не выполнено.
  • Если формат – read(buffer, count), возвращаются данные в буфер. Буферы можно ввести с помощью buffer.ibuf.
  • В случае ошибки метод возвращает nil, err и устанавливает ошибку на errno.
 
tarantool> ibuf = require('buffer').ibuf()
---
...

tarantool> fh:read(ibuf:reserve(5), 5)
---
- 5
...

tarantool> require('ffi').string(ibuf:alloc(5),5)
---
- abcde
file-handle:write(new-string)
file-handle:write(buffer, count)

Запись в файл не с произвольным доступом. Для получения подробной информации введите man 2 write.

Примечание

fh:read и fh:write влияют на положение поиска по файлу, и это следует учитывать при работе нескольких файберов над одним файлом. Существует возможность ограничения или запрета на доступ к файлу с помощью fiber.ipc. Можно ограничить или запретить доступ к файлам из других файберов с помощью fiber.cond() или fiber.channel().

Параметры:
  • fh (userdata) – дескриптор файла, который возвращает fio.open().
  • new-string (string) – записываемое значение (если формат – write(new-string))
  • buffer (cdata) – записываемое значение (если формат – write(buffer, count))
  • count (number) – количество байтов для чтения
возвращает:

true – если выполнено, false – если не выполнено.
тип возвращаемого значения:
 

boolean (логический)

Если формат – write(new-string), строка записывается в файл до конца строки.

Если формат – write(buffer, count), содержимое буфера записывается в файл в объеме, указанном в count. Буферы можно ввести с помощью buffer.ibuf.

Пример:

tarantool> fh:write("new data")
---
- true
...
tarantool> ibuf = require('buffer').ibuf()
---
...
tarantool> fh:write(ibuf, 1)
---
- true
...
file-handle:truncate(new-size)

Изменение размера открытого файла. Отличается от функции fio.truncate, которая изменяет размер закрытого файла.

Параметры:
  • fh (userdata) – дескриптор файла, который возвращает fio.open().
возвращает:

true – если выполнено, false – если не выполнено.
тип возвращаемого значения:
 

boolean (логический)

Пример:

tarantool> fh:truncate(0)
---
- true
...
file-handle:seek(position[, offset-from])

Изменение положения в файле на указанное. Для получения подробной информации введите man 2 seek.

Параметры:
  • fh (userdata) – дескриптор файла, который возвращает fio.open().
  • position (number) – искомое положение
  • offset-from (string) – „SEEK_END“ = конец файла, „SEEK_CUR“ = текущее положение, „SEEK_SET“ = начало файла.
возвращает:

новое положение, если выполнено
тип возвращаемого значения:
 

число

Возможные ошибки: nil.

Пример:

tarantool> fh:seek(20, 'SEEK_SET')
---
- 20
...
file-handle:stat()

Возврат статистики об открытом файле. Отличается от функции fio.stat, которая возвращает статистику о закрытом файле. Для получения подробной информации введите man 2 stat.

Параметры:
  • fh (userdata) – дескриптор файла, который возвращает fio.open().
возвращает:

подробная информация о файле.
тип возвращаемого значения:
 

таблица

Пример:

tarantool> fh:stat()
---
- inode: 729866
  rdev: 0
  size: 100
  atime: 140942855
  mode: 33261
  mtime: 1409430660
  nlink: 1
  uid: 1000
  blksize: 4096
  gid: 1000
  ctime: 1409430660
  dev: 2049
  blocks: 8
...
file-handle:fsync()
file-handle:fdatasync()

Проверка записи изменений в открытом файле на диск. Ср. с fio.sync для всех файлов. Для получения подробной информации введите man 2 fsync or man 2 fdatasync.

Параметры:
  • fh (userdata) – дескриптор файла, который возвращает fio.open().
возвращает:

true – если выполнено, false – если не выполнено.

Пример:

tarantool> fh:fsync()
---
- true
...

Постоянные для файлового ввода-вывода

fio.c

Таблица с постоянными, которые совпадают с флаговыми значениями в POSIX на целевой платформе (см. man 2 stat).

Пример:

tarantool> fio.c
---
- seek:
    SEEK_SET: 0
    SEEK_END: 2
    SEEK_CUR: 1
  mode:
    S_IWGRP: 16
    S_IXGRP: 8
    S_IROTH: 4
    S_IXOTH: 1
    S_IRUSR: 256
    S_IXUSR: 64
    S_IRWXU: 448
    S_IRWXG: 56
    S_IWOTH: 2
    S_IRWXO: 7
    S_IWUSR: 128
    S_IRGRP: 32
  flag:
    O_EXCL: 2048
    O_NONBLOCK: 4
    O_RDONLY: 0
    <...>
...

Модуль fun

Luafun, также известная как библиотека для функционального программирования в Lua, пользуется преимуществами LuaJIT, чтобы помочь пользователям создавать сложные функции. Модуль включает в себя «последовательные процессоры», такие как map, filter, reduce, zip – они берут написанную пользователем функцию в качестве аргумента и применяют ее к каждому элементу в последовательности, что может работать быстрее или более удобно, чем написанный пользователем цикл. Модуль включает в себя «генераторы», такие как range, tabulate и rands – они возвращают ограниченный или неограниченный ряд значений. Модуль включает в себя «преобразователи», «фильтры», «компоновщики» … или, коротко говоря, все важные функции из таких языков, как Standard ML, Haskell или Erlang.

The full documentation is On the luafun section of github. However, the first chapter can be skipped because installation is already done, it’s inside Tarantool. All that is needed is the usual require request. After that, all the operations described in the Lua fun manual will work, provided they are preceded by the name returned by the require request. For example:

tarantool> fun = require('fun')
---
...
tarantool> for _k, a in fun.range(3) do
         >   print(a)
         > end
1
2
3
---
...

Модуль http

The http module, specifically the http.client submodule, provides the functionality of an HTTP client with support for HTTPS and keepalive. The HTTP client uses the libcurl library under the hood and takes into account the environment variables libcurl understands.

HTTP client instance

Default client

The http.client submodule provides the default HTTP client instance:

local http_client = require('http.client')

In this case, you need to make requests using the dot syntax, for example:

local response = http_client.get('https://httpbin.org/get')

Creating a client

If you need to configure specific HTTP client options, use the http.client.new() function to create the client instance:

local http_client = require('http.client').new()

In this case, you need to make requests using the colon syntax, for example:

local response = http_client:get('https://httpbin.org/get')

All the examples in this section use the HTTP client created using http.client.new().

Making requests

The client instance enables you to make HTTP requests.

HTTP method

The main way of making HTTP requests is the request method, which accepts the following arguments:

  • An HTTP method, such as GET, POST, PUT, and so on.
  • A request URL. You can use the uri module to construct a URL from its components.
  • (Optional) a request body for the POST, PUT, and PATCH methods.
  • (Optional) request options, such as request headers, SSL settings, and so on.

The example below shows how to make the GET request to the https://httpbin.org/get URL:

local http_client = require('http.client').new()
local response = http_client:request('GET', 'https://httpbin.org/get')

In addition to request, the HTTP client provides the API for particular HTTP methods: get, post, put, and so on. For example, you can replace the request above by calling get as follows:

local http_client = require('http.client').new()
local response = http_client:get('https://httpbin.org/get')

Query parameters

To add query string parameters, use the params option exposed by the request_options object:

local http_client = require('http.client').new()
local response = http_client:get('https://httpbin.org/get', {
    params = { page = 1 },
})
print('URL: '..response.url)

In the example above, the requested URL is https://httpbin.org/get?page=1.

Примечание

If a parameter name or value contains a reserved character (for example, & or =), the HTTP client encodes a query string.

Headers

To add headers to the request, use the headers option:

local http_client = require('http.client').new()
local response = http_client:get('https://httpbin.org/headers', {
    headers = {
        ['User-Agent'] = 'Tarantool HTTP client',
        ['Authorization'] = 'Bearer abc123'
    }
})
print('Authorization: '..response:decode()['headers']['Authorization'])

Cookies

You can add cookies to the request using the headers option:

local http_client = require('http.client').new()
local response = http_client:get('https://httpbin.org/cookies', {
    headers = {
        ['Cookie'] = 'session_id=abc123; csrftoken=u32t4o;',
    }
})
print(response.body)

To learn how to obtain cookies passed in the Set-Cookie response header, see Response cookies.

Body

Serialization

The HTTP client automatically serializes the content in a specific format when sending a request based on the specified Content-Type header. By default, the client uses the application/json content type and sends data serialized as JSON:

local http_client = require('http.client').new()
local response = http_client:post('https://httpbin.org/anything', {
    user_id = 123,
    user_name = 'John Smith'
})
print('Posted data: '..response:decode()['data'])

The body for the request above might look like this:

{
    "user_id": 123,
    "user_name": "John Smith"
}

To send data in the YAML or MsgPack format, set the Content-Type header explicitly to application/yaml or application/msgpack, for example:

local http_client = require('http.client').new()
local response = http_client:post('https://httpbin.org/anything', {
    user_id = 123,
    user_name = 'John Smith'
}, {
    headers = {
        ['Content-Type'] = 'application/yaml',
    }
})
print('Posted data:\n'..response:decode()['data'])

In this case, the request body is serialized to YAML:

user_id: 123
user_name: John Smith

Form parameters

To send form parameters using the application/x-www-form-urlencoded type, use the params option:

local http_client = require('http.client').new()
local response = http_client:post('https://httpbin.org/anything', nil, {
    params = { user_id = 123, user_name = 'John Smith' },
})
print('User ID: '..response:decode()['form']['user_id'])

Streaming upload

The HTTP client supports chunked writing of request data. This can be achieved as follows:

  1. Set the chunked option to true. In this case, a request method returns io_object instead of response_object.
  2. Use the io_object.write() method to write a chunk of data.
  3. Call the io_object.finish() method to finish writing data and make a request.

The example below shows how to upload data in two chunks:

local http_client = require('http.client').new()
local json = require('json')

local io = http_client:post('https://httpbin.org/anything', nil, {chunked = true})
io:write('Data part 1')
io:write('Data part 2')
io:finish()
response = io:read('\r\n')
decoded_data = json.decode(response)
print('Posted data: '..decoded_data['data'])

Receiving responses

All methods that are used to make an HTTP request (request, get, post, etc.) receive response_object. response_object exposes the API required to get a response body and obtain response parameters, such as a status code, headers, and so on.

Status code

To get a response’s status code and text, use the response_object.status and response_object.reason options, respectively:

local http_client = require('http.client').new()
local response = http_client:get('https://httpbin.org/get')
print('Status: '..response.status..' '.. response.reason)

Headers

The response_object.headers option returns a set of response headers. The example below shows how to obtain the ETag header value:

local http_client = require('http.client').new()
local response = http_client:get('https://httpbin.org/etag/7c876b7e')
print('ETag header value: '..response.headers['etag'])

Cookies

To obtain response cookies, use response_object.cookies. This option returns a Lua table where a cookie name is the key. The value is an array of two elements where the first one is the cookie value and the second one is an array with the cookie’s options.

The example below shows how to obtain the session_id cookie value:

local http_client = require('http.client').new()
local response = http_client:get('https://httpbin.org/cookies/set?session_id=abc123&csrftoken=u32t4o&', {follow_location = false})
print("'session_id' cookie value: "..response.cookies['session_id'][1])

Response body

Deserialization

The HTTP client can deserialize response data to a Lua object based on the Content-Type response header value. To deserialize data, call the response_object.decode() method. In the example below, the JSON response is deserialized into a Lua object:

local http_client = require('http.client').new()
local response = http_client:get('https://httpbin.org/json')
local document = response:decode()
print("'title' value: "..document['slideshow']['title'])

The following content types are supported out of the box:

  • application/json
  • application/msgpack
  • application/yaml

If the response doesn’t have the Content-Type header, the client uses application/json.

To deserialize other content types, you need to provide a custom deserializer using the client_object.decoders property. In the example below, application/xml responses are decoded using the luarapidxml library:

local http_client = require('http.client').new()
local xml = require("luarapidxml")

http_client.decoders = {
    ['application/xml'] = function(body, _content_type)
        return xml.decode(body)
    end,
}

local response = http_client:get('https://httpbin.org/xml')
local document = response:decode()
print("'title' value: "..document['attr']['title'])

The output for the code sample above should look as follows:

'title' value: Sample Slide Show

Decompressing

The HTTP client can automatically decompress a response body based on the Content-Encoding header value. To enable this capability, pass the required formats using the request_options.accept_encoding option:

local http_client = require('http.client').new()
local response = http_client:get('https://httpbin.org/gzip', {accept_encoding = "br, gzip, deflate"})
print('Is response gzipped: '..tostring(response:decode()['gzipped']))

Streaming download

The HTTP client supports chunked reading of request data. This can be achieved as follows:

  1. Set the chunked option to true. In this case, a request method returns io_object instead of response_object.
  2. Use the io_object.read() method to read data in chunks of a specified length or up to a specific delimiter.
  3. Call the io_object.finish() method to finish reading data.

The example below shows how to get chunks of a JSON response sequentially instead of waiting for the entire response:

local http_client = require('http.client').new()
local json = require('json')

local io = http_client:get('https://httpbin.org/stream/5', {chunked = true})
local chunk_ids = ''
while data ~= '' do
    local data = io:read('\n')
    if data == '' then break end
    local decoded_data = json.decode(data)
    chunk_ids = chunk_ids..decoded_data['id']..' '
end
print('IDs of received chunks: '..chunk_ids)
io:finish()

Redirects

By default, the HTTP client redirects to a URL provided in the Location header of a 3xx response. If required, you can disable redirection using the follow_location option:

local http_client = require('http.client').new()
local response = http_client:get('https://httpbin.org/cookies/set?session_id=abc123&csrftoken=u32t4o&', {follow_location = false})

API Reference

Functions  
http.client.new() Создание экземпляра HTTP-клиента
Objects  
client_options Configuration options of the client
client_object An HTTP client instance
request_options Options passed to a request
response_object A response object
io_object An IO object used to read/write data in chunks

http.client.new()

http.client.new([options])

Create an HTTP client instance.

Параметры:
возвращает:

a new HTTP client instance (see client_object)
тип возвращаемого значения:
 

пользовательские данные

Пример:

local http_client = require('http.client').new()

client_options

object client_options

Configuration options of the client. These options can be passed to the http.client.new() function.

client_options.max_connections

Specifies the maximum number of entries in the cache. This option affects libcurl CURLMOPT_MAXCONNECTS. The default is -1.

Пример:

local http_client = require('http.client').new({max_connections = 5})

Note

Do not set max_connections to less than max_total_connections unless you are confident about your actions. If max_connections is less than max_total_connections, libcurl doesn’t reuse sockets in some cases for requests that go to the same host. If the limit is reached and a new request occurs, then libcurl creates a new socket first, sends the request, waits for the first connection to be free, and closes it to avoid exceeding the max_connections cache size. In the worst case, libcurl creates a new socket for every request, even if all requests go to the same host.

client_options.max_total_connections

Specifies the maximum number of active connections. This option affects libcurl CURLMOPT_MAX_TOTAL_CONNECTIONS.

Note

You may want to control the maximum number of sockets that a particular HTTP client uses simultaneously. If a system passes many requests to distinct hosts, then libcurl cannot reuse sockets. In this case, setting max_total_connections may be useful since it causes curl to avoid creating too many sockets, which would not be used anyway.

client_object

object client_object

An HTTP client instance that exposes the API for making requests. To create the client, call http.client.new().

client_object:request(method, url, body, opts)

Make an HTTP request and receive a response.

Параметры:
  • method (string) – a request HTTP method. Possible values: GET, POST, PUT, PATCH, OPTIONS, HEAD, DELETE, TRACE, CONNECT.
  • url (string) – a request URL, for example, https://httpbin.org/get
  • body (string) – a request body (see Body)
  • opts (table) – request options (see request_options)
возвращает:

This method returns one of the following objects:
тип возвращаемого значения:
 

таблица

Пример:

local http_client = require('http.client').new()
local response = http_client:request('GET', 'https://httpbin.org/get')

See also: Making requests, Receiving responses

client_object:get(url, opts)

Make a GET request and receive a response.

Параметры:
возвращает:

This method might return one of the following objects:
тип возвращаемого значения:
 

таблица

Пример:

local http_client = require('http.client').new()
local response = http_client:get('https://httpbin.org/get')

See also: Making requests, Receiving responses

client_object:post(url, body, opts)

Make a POST request and receive a response.

Параметры:
возвращает:

This method might return one of the following objects:
тип возвращаемого значения:
 

таблица

Пример:

local http_client = require('http.client').new()
local response = http_client:post('https://httpbin.org/anything', {
    user_id = 123,
    user_name = 'John Smith'
})
print('Posted data: '..response:decode()['data'])

See also: Making requests, Receiving responses

client_object:put(url, body, opts)

Make a PUT request and receive a response.

Параметры:
возвращает:

This method might return one of the following objects:
тип возвращаемого значения:
 

таблица

See also: Making requests, Receiving responses

client_object:patch(url, body, opts)

Make a PATCH request and receive a response.

Параметры:
возвращает:

This method might return one of the following objects:
тип возвращаемого значения:
 

таблица

See also: Making requests, Receiving responses

client_object:delete(url, opts)

Make a DELETE request and receive a response.

Параметры:
возвращает:

This method might return one of the following objects:
тип возвращаемого значения:
 

таблица

See also: Making requests, Receiving responses

client_object:head(url, opts)

Make a HEAD request and receive a response.

Параметры:
возвращает:

This method might return one of the following objects:
тип возвращаемого значения:
 

таблица

See also: Making requests, Receiving responses

client_object:options(url, opts)

Make an OPTIONS request and receive a response.

Параметры:
возвращает:

This method might return one of the following objects:
тип возвращаемого значения:
 

таблица

See also: Making requests, Receiving responses

client_object:trace(url, opts)

Make a TRACE request and receive a response.

Параметры:
возвращает:

This method might return one of the following objects:
тип возвращаемого значения:
 

таблица

See also: Making requests, Receiving responses

client_object:connect(url, opts)

Make a CONNECT request and receive a response.

Параметры:
возвращает:

This method might return one of the following objects:
тип возвращаемого значения:
 

таблица

See also: Making requests, Receiving responses

client_object:stat()

Get a table with statistics for the HTTP client:

  • active_requests – the number of currently executing requests
  • sockets_added – the total number of sockets added into an event loop
  • sockets_deleted – the total number of sockets deleted from an event loop
  • total_requests – the total number of requests
  • http_200_responses – the total number of requests that returned HTTP 200 OK responses
  • http_other_responses – the total number of requests that returned non-200 OK responses
  • failed_requests – the total number of failed requests, including system, curl, and HTTP errors
client_object.decoders

Since: 2.11.0

Decoders used to deserialize response data based on the Content-Type header value. Learn more from Deserialization.

request_options

object request_options

Options passed to a request method (request, get, post, and so on).

See also: Making requests

request_options.ca_file

The path to an SSL certificate file to verify the peer with.

тип возвращаемого значения:
 string
request_options.ca_path

The path to a directory holding one or more certificates to verify the peer with.

тип возвращаемого значения:
 string
request_options.chunked

Since: 2.11.0

Specifies whether an HTTP client should return the full response (response_object) or an IO object (io_object) used for streaming download/upload.

тип возвращаемого значения:
 boolean

See also: Streaming download, Streaming upload

request_options.headers

A table of HTTP headers passed to a request.

тип возвращаемого значения:
 таблица
request_options.params

Since: 2.11.0

A table of parameters passed to a request. The behavior of this option depends on the request type, for example:

тип возвращаемого значения:
 таблица
request_options.keepalive_idle

A delay (in seconds) the operating system waits while the connection is idle before sending keepalive probes.

тип возвращаемого значения:
 integer

See also: CURLOPT_TCP_KEEPIDLE, keepalive_interval

request_options.keepalive_interval

The interval (in seconds) the operating system waits between sending keepalive probes. If both keepalive_idle and keepalive_interval are set, then Tarantool also sets the HTTP keepalive headers: Connection:Keep-Alive and Keep-Alive:timeout=<keepalive_idle>. Otherwise, Tarantool sends Connection:close.

тип возвращаемого значения:
 integer

See also: CURLOPT_TCP_KEEPINTVL

request_options.low_speed_limit

The average transfer speed in bytes per second that the transfer should be below during «low speed time» seconds for the library to consider it to be too slow and abort.

тип возвращаемого значения:
 integer

See also: CURLOPT_LOW_SPEED_LIMIT

request_options.low_speed_time

The time that the transfer speed should be below the «low speed limit» for the library to consider it too slow and abort.

тип возвращаемого значения:
 integer

See also: CURLOPT_LOW_SPEED_TIME

request_options.max_header_name_len

The maximum length of a header name. If a header name length exceeds this value, it is truncated to this length. The default value is 32.

тип возвращаемого значения:
 integer
request_options.follow_location

Specify whether the HTTP client follows redirect URLs provided in the Location header for 3xx responses. When a non-3xx response is received, the client returns it as a result. If you set this option to false, the client returns the first 3xx response.

тип возвращаемого значения:
 boolean

See also: Redirects

request_options.no_proxy

A comma-separated list of hosts that do not require proxies, or *, or ''.

  • Set no_proxy = host [, host ...] to specify hosts that can be reached without requiring a proxy, even if proxy is set to a non-blank value and/or if a proxy-related environment variable has been set.
  • Set no__proxy = '*' to specify that all hosts can be reached without requiring a proxy, which is equivalent to setting proxy=''.
  • Set no_proxy = '' to specify that no hosts can be reached without requiring a proxy, even if a proxy-related environment variable (HTTP_PROXY) is used.

If no_proxy is not set, then a proxy-related environment variable (HTTP_PROXY) may be used.

тип возвращаемого значения:
 string

See also: CURLOPT_NOPROXY

request_options.proxy

A proxy server host or IP address, or ''.

  • If proxy is a host or IP address, then it may begin with a scheme, for example, https:// for an HTTPS proxy or http:// for an HTTP proxy.
  • If proxy is set to '' an empty string, then proxy use is disabled, and no proxy-related environment variable is used.
  • If proxy is not set, then a proxy-related environment variable may be used, such as HTTP_PROXY or HTTPS_PROXY or FTP_PROXY, or ALL_PROXY if the protocol can be any protocol.
тип возвращаемого значения:
 string

See also: CURLOPT_PROXY

request_options.proxy_port

A proxy server port. The default is 443 for an HTTPS proxy and 1080 for a non-HTTPS proxy.

тип возвращаемого значения:
 integer

See also: CURLOPT_PROXYPORT

request_options.proxy_user_pwd

A proxy server username and password. This option might have one of the following formats:

  • proxy_user_pwd = user_name:
  • proxy_user_pwd = :password
  • proxy_user_pwd = user_name:password
тип возвращаемого значения:
 string

See also: CURLOPT_USERPWD

request_options.ssl_cert

A path to an SSL client certificate file.

тип возвращаемого значения:
 string

See also: CURLOPT_SSLCERT

request_options.ssl_key

A path to a private key file for a TLS and SSL client certificate.

тип возвращаемого значения:
 string

See also: CURLOPT_SSLKEY

request_options.timeout

The number of seconds to wait for a curl API read request before timing out. The default timeout is set to infinity (36586400100 seconds).

тип возвращаемого значения:
 integer
request_options.unix_socket

A socket name to use instead of an Internet address for a local connection.

тип возвращаемого значения:
 string

Example: /tmp/unix_domain_socket.sock

request_options.verbose

Turn on/off a verbose mode.

тип возвращаемого значения:
 boolean
request_options.verify_host

Enable verification of the certificate’s name (CN) against the specified host.

тип возвращаемого значения:
 integer

See also: CURLOPT_SSL_VERIFYHOST

request_options.verify_peer

Set on/off verification of the peer’s SSL certificate.

тип возвращаемого значения:
 integer

See also: CURLOPT_SSL_VERIFYPEER

request_options.accept_encoding

Enable decompression of an HTTP response data based on the specified Accept-Encoding request header. You can pass the following values to this option:

  • '' – if an empty string is passed, the Accept-Encoding contains all the supported encodings (identity, deflate, gzip, and br).
  • br, gzip, deflate – a comma-separated list of encodings passed in Accept-Encoding.
тип возвращаемого значения:
 string

See also: CURLOPT_ACCEPT_ENCODING

response_object

object response_object

A response object returned by a request method (request, get, post, and so on).

See also: io_object

response_object.status

A response status code.

тип возвращаемого значения:
 integer

See also: Status code

response_object.reason

A response status text.

тип возвращаемого значения:
 string

See also: Status code

response_object.headers

Response headers.

тип возвращаемого значения:
 таблица

See also: Headers

response_object.cookies

Response cookies. The value is an array of two elements where the first one is the cookie value and the second one is an array with the cookie’s options.

тип возвращаемого значения:
 таблица

See also: Cookies

response_object.body

A response body. Use decode to decode the response body.

тип возвращаемого значения:
 таблица

See also: Response body

response_object.proto

An HTTP protocol version.

тип возвращаемого значения:
 string
response_object:decode()

Since: 2.11.0

Decode the response body to a Lua object based on the content type.

возвращает:a decoded body
тип возвращаемого значения:
 таблица

See also: Deserialization

io_object

object io_object

Since: 2.11.0

An IO object used to read or write data in chunks. To get an IO object instead of the full response (response_object), you need to set the chunked request option to true.

io_object:read(chunk[, timeout])
io_object:read(delimiter[, timeout])
io_object:read({chunk = chunk, delimiter = delimiter}[, timeout])

Read request data in chunks of a specified length or up to a specific delimiter.

Параметры:
  • chunk (integer) – the maximum number of bytes to read
  • delimiter (string) – the delimiter used to stop reading data
  • timeout (integer) – the number of seconds to wait. The default is 10.
возвращает:

A chunk of read data. Returns an empty string if there is nothing more to read.
тип возвращаемого значения:
 

string

See also: Streaming download

io_object:write(data[, timeout])

Write the specified chunk of data.

Параметры:
  • data (table) – data to be written
  • timeout (integer) – the number of seconds to wait. The default is 10.

See also: Streaming upload

io_object:finish([timeout])

Finish reading or writing data.

Параметры:
  • timeout (integer) – the number of seconds to wait. The default is 10.

See also: Streaming download, Streaming upload

Модуль iconv

Общие сведения

Модуль iconv предоставляет метод конвертации строки с одним типом кодировки в строку с другим типом кодировки, например из ASCII в UTF-8. Он основывается на процедурах с iconv в POSIX.

Точный список доступных кодировок зависит от окружения. Как правило, в список входят ASCII, BIG5, KOI8R, LATIN8, MS-GREEK, SJIS и около 100 других. Чтобы увидеть общий список, введите команду iconv --list в терминале.

Указатель

Ниже приведен перечень всех функций модуля iconv.

Имя Назначение
iconv.new() Создание экземпляра iconv
iconv.converter() Преобразование строки
iconv.new(to, from)

Создание нового iconv-экземпляра.

Параметры:
  • to (string) – название будущей кодировки.
  • from (string) – название используемой кодировки.
возвращает:

новый экземпляр iconv – на самом деле, вызываемая функция
тип возвращаемого значения:
 

пользовательские данные

Если значение одного из параметров представляет собой недопустимое имя, появится сообщение об ошибке.

Пример:

tarantool> converter = require('iconv').new('UTF8', 'ASCII')
---
...
iconv.converter(input-string)

Преобразование.

param string input-string:
 строка для преобразования («из»)
возвращает:строка, получаемая в результате преобразования («в»)

Если что-либо в строке input-string нельзя преобразовать, появится сообщение об ошибке, строка останется неизменной.

Пример:

We know that the Unicode code point for «Д» (CYRILLIC CAPITAL LETTER DE) is hexadecimal 0414 according to the character database of Unicode. Therefore that is what it will look like in UTF-16. We know that Tarantool typically uses the UTF-8 character set. So make a from-UTF-8-to-UTF-16 converter, use string.hex(„Д“) to show what Д’s encoding looks like in the UTF-8 source, and use string.hex(„Д“-after-conversion) to show what it looks like in the UTF-16 target. Since the result is 0414, we see that iconv conversion works. (Different iconv implementations might use different names, for example UTF-16BE instead of UTF16BE.)

tarantool> string.hex('Д')
---
- d094
...

tarantool> converter = require('iconv').new('UTF16BE', 'UTF8')
---
...

tarantool> utf16_string = converter('Д')
---
...

tarantool> string.hex(utf16_string)
---
- '0414'
...

Module jit

Overview

The jit module has functions for tracing the LuaJIT Just-In-Time compiler’s progress, showing the byte-code or assembler output that the compiler produces, and in general providing information about what LuaJIT does with Lua code.

Index

Below is a list of all jit functions.

Примечание

In this document, we will use:
  • jit_dis_x64 for require('jit.dis_x64'),
  • jit_v for require('jit.v'),
  • jit_dump for require('jit.dump').
Name Use
jit_bc.dump() Print the byte code of a function
jit_dis_x86.disass() Print the i386 assembler code of a string of bytes
jit_dis_x64.disass() Print the x86-64 assembler code of a string of bytes
jit_dump.on(), jit_dump.off() Print the intermediate or machine code of the following Lua code
jit_v.on(), jit_v.off() Print a trace of LuaJIT’s progress compiling and interpreting code
jit_bc.dump(function)

Prints the byte code of a function.

Example:

tarantool> jit_bc = require('jit.bc')
---
...

tarantool> function f()
         > print("D")
         > end
---
...

tarantool> jit_bc.dump(f)
-- BYTECODE -- 0x01113163c8:1-3
0001    GGET     0   0      ; "print"
0002    KSTR     2   1      ; "D"
0003    CALL     0   1   2
0004    RET0     0   1

---
...

function f()
  print("D")
end
require('jit.bc').dump(f)

For a list of available options, read the source code of bc.lua.

jit_dis_x86.disass(string)

Prints the i386 assembler code of a string of bytes.

Example:

tarantool> -- Disassemble hexadecimal 97 which is the x86 code for xchg eax, edi
---
...

tarantool> jit_dis_x86 = require('jit.dis_x86')
---
...

tarantool> jit_dis_86.disass('\x97')
00000000  97                xchg eax, edi
---
...

For a list of available options, read the source code of dis_x86.lua.

jit_dis_x64.disass(string)

Prints the x86-64 assembler code of a string of bytes.

Example:

tarantool> -- Disassemble hexadecimal 97 which is the x86-64 code for xchg eax, edi
---
...

tarantool> jit_dis_x64 = require('jit.dis_x64')
---
...

tarantool> jit_dis_64.disass('\x97')
00000000  97                xchg eax, edi
---
...

For a list of available options, read the source code of dis_x64.lua.

jit_dump.on(option[, output file])
jit_dump.off()

Prints the intermediate or machine code of the following Lua code.

Example:

tarantool> -- Show the machine code of a Lua "for" loop
tarantool> jit_dump = require('jit.dump')
tarantool> jit_dump.on('m')
tarantool> x = 0;
tarantool> for i = 1, 1e6 do
         > x = x + i
         > end
---- TRACE 1 start 0x01047fbc38:1
---- TRACE 1 mcode 148
104c29f6b  mov dword [r14-0xed0], 0x1
104c29f76  cvttsd2si ebp, [rdx]
104c29f7a  rorx rbx, [rdx-0x10], 0x2f
104c29f81  shr rbx, 0x11
104c29f85  mov rdx, [rbx+0x10]
104c29f89  cmp dword [rdx+0x34], +0x3f
104c29f8d  jnz 0x104c1a010  ->0
104c29f93  mov rcx, [rdx+0x28]
104c29f97  mov rdi, 0xfffd8001046b3d58
104c29fa1  cmp rdi, [rcx+0x320]
104c29fa8  jnz 0x104c1a010  ->0
104c29fae  lea rax, [rcx+0x318]
104c29fb5  cmp dword [rax+0x4], 0xfff90000
104c29fbc  jnb 0x104c1a010  ->0
104c29fc2  xorps xmm7, xmm7
104c29fc5  cvtsi2sd xmm7, ebp
104c29fc9  addsd xmm7, [rax]
104c29fcd  movsd [rax], xmm7
104c29fd1  add ebp, +0x01
104c29fd4  cmp ebp, 0x000f4240
104c29fda  jg 0x104c1a014   ->1
->LOOP:
104c29fe0  xorps xmm6, xmm6
104c29fe3  cvtsi2sd xmm6, ebp
104c29fe7  addsd xmm7, xmm6
104c29feb  movsd [rax], xmm7
104c29fef  add ebp, +0x01
104c29ff2  cmp ebp, 0x000f4240
104c29ff8  jle 0x104c29fe0  ->LOOP
104c29ffa  jmp 0x104c1a01c  ->3
---- TRACE 1 stop -> loop

---
...

tarantool> print(x)
500000500000
---
...

tarantool> jit_dump.off()
---
...

For a list of available options, read the source code of dump.lua.

jit_v.on(option[, output file])
jit_v.off()

Prints a trace of LuaJIT’s progress compiling and interpreting code.

Example:

tarantool> -- Show what LuaJIT is doing for a Lua "for" loop
tarantool> jit_v = require('jit.v')
tarantool> jit_v.on()
tarantool> l = 0
tarantool> for i = 1, 1e6 do
         >     l = l + i
         > end
[TRACE   3 "for i = 1, 1e6 do
    l = l + i
end":1 loop]
---
...

tarantool> print(l)
500000500000
---
...

tarantool> jit_v.off()
---
...

For a list of available options, read the source code of v.lua.

Модуль json

Общие сведения

Модуль json определяет процедуры работы с форматом JSON. Он создан на основе модуля Lua-CJSON от Mark Pulford. Полное руководство по Lua-CJSON включено в официальную документацию.

Указатель

Ниже приведен перечень всех функций и элементов модуля json.

Имя Назначение
json.encode() Конвертация Lua-объекта в JSON-строку
json.decode() Конвертация JSON-строки в Lua-объект
__serialize parameter Output structure specification
json.cfg() Изменение конфигурации
json.NULL Аналог «nil» в языке Lua
json.encode(lua-value[, configuration])

Конвертация Lua-объекта в JSON-строку.

Параметры:
  • lua_value – скалярное значение или значение из Lua-таблицы.
  • configuration – see json.cfg
возвращает:

оригинальное значение, преобразованное в JSON-строку.
тип возвращаемого значения:
 

строка

Пример:

tarantool> json=require('json')
---
...
tarantool> json.encode(123)
---
- '123'
...
tarantool> json.encode({123})
---
- '[123]'
...
tarantool> json.encode({123, 234, 345})
---
- '[123,234,345]'
...
tarantool> json.encode({abc = 234, cde = 345})
---
- '{"cde":345,"abc":234}'
...
tarantool> json.encode({hello = {'world'}})
---
- '{"hello":["world"]}'
...
json.decode(string[, configuration])

Конвертация JSON-строки в Lua-объект.

Параметры:
  • string (string) – строка в формате JSON.
  • configuration – see json.cfg
возвращает:

оригинальное содержание в формате Lua-таблицы.
тип возвращаемого значения:
 

таблица

Пример:

tarantool> json = require('json')
---
...
tarantool> json.decode('123')
---
- 123
...
tarantool> json.decode('[123, "hello"]')
---
- [123, 'hello']
...
tarantool> json.decode('{"hello": "world"}').hello
---
- world
...

Чтобы увидеть применение json.decode() в приложении, см. практическое задание Подсчет суммы по JSON-полям во всех кортежах.

__serialize parameter:

Структуру JSON-вывода можно указать с помощью __serialize:

Serializing „A“ and „B“ with different __serialize values brings different results:

tarantool> json.encode(setmetatable({'A', 'B'}, { __serialize="seq"}))
---
- '["A","B"]'
...
tarantool> json.encode(setmetatable({'A', 'B'}, { __serialize="map"}))
---
- '{"1":"A","2":"B"}'
...
tarantool> json.encode({setmetatable({f1 = 'A', f2 = 'B'}, { __serialize="map"})})
---
- '[{"f2":"B","f1":"A"}]'
...
tarantool> json.encode({setmetatable({f1 = 'A', f2 = 'B'}, { __serialize="seq"})})
---
- '[[]]'
...
json.cfg(table)

Set values that affect the behavior of json.encode and json.decode.

The values are all either integers or boolean true/false.

Характеристика Значение по умолчанию Назначение
cfg.encode_max_depth 128 Max recursion depth for encoding
cfg.encode_deep_as_nil false (ложь) A flag saying whether to crop tables with nesting level deeper than cfg.encode_max_depth. Not-encoded fields are replaced with one null. If not set, too deep nesting is considered an error.
cfg.encode_invalid_numbers true A flag saying whether to enable encoding of NaN and Inf numbers
cfg.encode_number_precision 14 Precision of floating point numbers
cfg.encode_load_metatables true A flag saying whether the serializer will follow __serialize metatable field
cfg.encode_use_tostring false (ложь) A flag saying whether to use tostring() for unknown types
cfg.encode_invalid_as_nil false (ложь) A flag saying whether use NULL for non-recognized types
cfg.encode_sparse_convert true A flag saying whether to handle excessively sparse arrays as maps. See detailed description below.
cfg.encode_sparse_ratio 2 1/encode_sparse_ratio is the permissible percentage of missing values in a sparse array.
cfg.encode_sparse_safe 10 A limit ensuring that small Lua arrays are always encoded as sparse arrays (instead of generating an error or encoding as a map)
cfg.decode_invalid_numbers true A flag saying whether to enable decoding of NaN and Inf numbers
cfg.decode_save_metatables true A flag saying whether to set metatables for all arrays and maps
cfg.decode_max_depth 128 Max recursion depth for decoding

Sparse arrays features:

During encoding, the JSON encoder tries to classify a table into one of four kinds:

An array is excessively sparse when all the following conditions are met:

The JSON encoder will never consider an array to be excessively sparse when encode_sparse_ratio = 0. The encode_sparse_safe limit ensures that small Lua arrays are always encoded as sparse arrays. By default, attempting to encode an excessively sparse array will generate an error. If encode_sparse_convert is set to true, excessively sparse arrays will be handled as maps.

json.cfg() example 1:

The following code will encode 0/0 as NaN («not a number») and 1/0 as Inf («infinity»), rather than returning nil or an error message:

json = require('json')
json.cfg{encode_invalid_numbers = true}
x = 0/0
y = 1/0
json.encode({1, x, y, 2})

Результат запроса json.encode() будет следующим:

tarantool> json.encode({1, x, y, 2})
---
- '[1,nan,inf,2]
...

json.cfg example 2:

To avoid generating errors on attempts to encode unknown data types as userdata/cdata, you can use this code:

tarantool> httpc = require('http.client').new()
---
...

tarantool> json.encode(httpc.curl)
---
- error: unsupported Lua type 'userdata'
...

tarantool> json.encode(httpc.curl, {encode_use_tostring=true})
---
- '"userdata: 0x010a4ef2a0"'
...

Примечание

To achieve the same effect for only one call to json.encode() (i.e. without changing the configuration permanently), you can use json.encode({1, x, y, 2}, {encode_invalid_numbers = true}).

Similar configuration settings exist for MsgPack and YAML.

json.NULL

Значение, сопоставимое с нулевым значением «nil» в языке Lua, которое можно использовать в качестве объекта-заполнителя в кортеже.

Пример:

-- Когда полю Lua-таблицы присваивается nil, это поле -- null
tarantool> {nil, 'a', 'b'}
---
- - null
  - a
  - b
...
-- Когда полю Lua-таблицы присваивается json.NULL, это поле --  json.NULL
tarantool> {json.NULL, 'a', 'b'}
---
- - null
  - a
  - b
...
-- Когда JSON-полю присваивается json.NULL, это поле -- null
tarantool> json.encode({field2 = json.NULL, field1 = 'a', field3 = 'c'})
---
- '{"field2":null,"field1":"a","field3":"c"}'
...

Модуль key_def

В модуле key_def есть функция, позволяющая создавать определение номеров и типов полей кортежа. Это определение обычно используется вместе с определением индекса, чтобы извлекать или сравнивать значения ключей индекса.

key_def.new(parts)

Создание нового экземпляра key_def.

Параметры:
  • parts (table) – типы и номера полей. В таблице parts должен быть хотя бы один элемент. Для каждого элемента обязательны только атрибуты type и fieldno/field.
возвращает:

объект key_def

The parts table has components which are the same as the parts option in Options for space_object:create_index().

fieldno (целое число), например fieldno = 1. Вместо fieldno можно использовать field.

type (строка), например type = 'string'.

Остальные компоненты необязательны.

Пример №1: key_def.new({{type = 'unsigned', fieldno = 1}})

Пример №2: key_def.new({{type = 'string', collation = 'unicode', field = 2}})

object key_def_object

Объект key_def возвращается функцией key_def.new(). У него есть следующие методы: extract_key(), compare(), compare_with_key(), merge(), totable().

key_def_object:extract_key(tuple)

Получение кортежа, содержащего только поля объекта key_def.

Параметры:
  • tuple (table) – кортеж или Lua-таблица с содержимым поля
возвращает:

поля, определенные для объекта key_def,

Пример №1:

--  Предположим, что у некоторого элемента пять полей:
-- 1, 99.5, 'X', nil, 99.5
-- Нас интересуют только два из них:
-- третье (строка) и первое (целое число).
-- Мы можем определить эти поля инструкцией k = key_def.new
--  и извлечь значения командой k:extract_key.

tarantool> key_def = require('key_def')
---
...

tarantool> k = key_def.new({{type = 'string', fieldno = 3},
>                           {type = 'unsigned', fieldno = 1}})
---
...

tarantool> k:extract_key({1, 99.5, 'X', nil, 99.5})
---
- ['X', 1]
...

Пример №2

-- Теперь предположим, что элемент является кортежем в спейсе.
-- У спейса есть составной индекс, построенный по полям 3 и 1.
-- Мы можем передать определение индекса в качестве аргумента функции key_def.new,
-- а не заполнять определение, как в примере №1.
-- Результат будет тот же.
key_def = require('key_def')
box.schema.space.create('T')
i = box.space.T:create_index('I', {parts={3, 'string', 1, 'unsigned'}})
box.space.T:insert{1, 99.5, 'X', nil, 99.5}
k = key_def.new(i.parts)
k:extract_key(box.space.T:get({'X', 1}))

Пример №3

-- Проходим по всем кортежам во вторичном неуникальном индексе
-- и извлекаем из них значения по первичному ключу.
-- Затем удаляем значения, используя уникальный индекс.
-- Этот код должен входить в Lua-функцию.
local key_def_lib = require('key_def')
local s = box.schema.space.create('test')
local pk = s:create_index('pk')
local sk = s:create_index('test', {unique = false, parts = {
    {2, 'number', path = 'a'}, {2, 'number', path = 'b'}}})
s:insert{1, {a = 1, b = 1}}
s:insert{2, {a = 1, b = 2}}
local key_def = key_def_lib.new(pk.parts)
for _, tuple in sk:pairs({1})) do
    local key = key_def:extract_key(tuple)
    pk:delete(key)
end
key_def_object:compare(tuple_1, tuple_2)

Сравнение полей кортежей tuple_1 и tuple_2 по определённому ключу. Пользователю не нужно писать код для сравнения отдельных полей. Учитываются типы полей и параметры сортировки. Фактически сравниваются значения extract_key(tuple_1) и extract_key(tuple_2).

Параметры:
  • tuple1 (table) – кортеж или Lua-таблица с содержимым поля
  • tuple2 (table) – кортеж или Lua-таблица с содержимым поля
возвращает:

положительное число, если значения полей tuple_1 больше значений полей tuple_2 по ключу; 0, если они равны; отрицательное число, если значения полей tuple_1 меньше значений полей tuple_2 по ключу

Пример:

-- Результат этого кода будет 0
key_def = require('key_def')
k = key_def.new({{type = 'string', fieldno = 3, collation = 'unicode_ci'},
                 {type = 'unsigned', fieldno = 1}})
k:compare({1, 99.5, 'X', nil, 99.5}, {1, 99.5, 'x', nil, 99.5})
key_def_object:compare_with_key(tuple_1, tuple_2)

Сравнение полей кортежей tuple_1 с полями кортежа tuple_2 по заданному ключу. Аналогично key_def_object:compare(), за исключением того, что tuple_2 содержит только поля ключа. Фактически это сравнение extract_key(tuple_1) с tuple_2.

Параметры:
  • tuple1 (table) – кортеж или Lua-таблица с содержимым поля
  • tuple2 (table) – кортеж или Lua-таблица с содержимым поля
возвращает:

положительное число, если значения полей tuple_1 больше значений полей tuple_2 по ключу; 0, если они равны; отрицательное число, если значения полей tuple_1 меньше значений полей tuple_2 по ключу

Пример:

-- Результат этого кода будет 0
key_def = require('key_def')
k = key_def.new({{type = 'string', fieldno = 3, collation = 'unicode_ci'},
                 {type = 'unsigned', fieldno = 1}})
k:compare_with_key({1, 99.5, 'X', nil, 99.5}, {'x', 1})
key_def_object:merge(other_key_def_object)

Объединение основного объекта key_def_object с другим объектом other_key_def_object. Возвращает новый объект key_def_object, содержащий сначала все поля основного объекта key_def_object, а потом те поля объекта other_key_def_object, которых не было в основном объекте key_def_object.

Параметры:
  • other_key_def_object (key_def_object) – определение полей, которые нужно добавить
возвращает:

key_def_object

Пример:

-- Результатом этого кода будет определение ключа
-- по полям с fieldno = 3 и fieldno = 1
key_def = require('key_def')
k = key_def.new({{type = 'string', fieldno = 3}})
k2= key_def.new({{type = 'unsigned', fieldno = 1},
                 {type = 'string', fieldno = 3}})
k:merge(k2)
key_def_object:totable()

Возвращает таблицу с содержимым key_def_object. Функция противоположна функции key_def.new():

  • key_def.new() принимает таблицу, а возвращает объект key_def.
  • key_def_object:totable() принимает объект key_def, а возвращает таблицу.

Это удобно при подготовке входных данных для методов сериализации (_serialize).

возвращает:таблица

Пример:

-- Результатом этого кода будет таблица с type = 'string', fieldno = 3
key_def = require('key_def')
k = key_def.new({{type = 'string', fieldno = 3}})
k:totable()

Модуль log

Общие сведения

Tarantool provides a set of options used to configure logging in various ways: you can set a level of logging, specify where to send the log’s output, configure a log format, and so on. The log module allows you to configure logging in your application and provides additional capabilities, for example, logging custom messages and rotating log files.

Указатель

Ниже приведен перечень всех функций и элементов модуля log.

Имя Назначение
log.cfg({}) Configure a logger
log.error()
log.warn()
log.info()
log.verbose()
log.debug()		 Log a message with the specified level
log.pid() Получение PID регистратора записи в журнале
log.rotate() Ротация файла журнала
log.new() Create a new logger with the specified name
log.cfg({})

Configure logging options. The following options are available:

  • level: Specify the level of detail the log has.

    The example below shows how to set the log level to verbose:

    local log = require('log')
log.cfg { level = 'verbose' }

    See also: log.level.

  • log: Specify where to send the log’s output, for example, to a file, pipe, or system logger.

    Example 1: sending the log to the tarantool.log file

    log.cfg { log = 'tarantool.log' }

    Example 2: sending the log to a pipe

    log.cfg { log = '| cronolog tarantool.log' }

    Example 3: sending the log to syslog

    log.cfg { log = 'syslog:server=unix:/dev/log' }

    See also: log.to.

  • nonblock: If true, Tarantool does not block during logging when the system is not ready for writing, and drops the message instead.

    See also: log.nonblock.

  • format: Specify the log format: „plain“ or „json“.

    See also: log.format.

  • modules: Configure the specified log levels for different modules.

    See also: log.modules.

log.error(message)
log.warn(message)
log.info(message)
log.verbose(message)
log.debug(message)

Log a message with the specified logging level. You can learn more about the available levels from the log.level option description.

Example

The example below shows how to log a message with the warn level:

log.warn('Warning message')
Параметры:
  • message (any) –

    A log message.

    • A message can be a string.
    • A message may contain C-style format specifiers %d or %s. Example:
      log.info('Tarantool version: %s', box.info.version)
    • A message may be a scalar data type or a table. Example:
      log.error({ 500, 'Internal error' })
возвращает:

nil

Выходное значение будет представлять собой строку в журнале, которая содержит следующее:

  • the current timestamp
  • a module name
  • „E“, „W“, „I“, „V“ or „D“ depending on the called function
  • message

Note that the message will not be logged if the severity level corresponding to the called function is less than log.level.

log.pid()
возвращает:A PID of a logger. You can use this PID to send a signal to a log rotation program, so it can rotate logs.
log.rotate()

Rotate the log. For example, you need to call this function to continue logging after a log rotation program renames or moves a file with the latest logs.

возвращает:nil
log.new(name)

Since: 2.11.0

Create a new logger with the specified name. You can configure a specific log level for a new logger using the log.modules configuration property.

Параметры:
  • name (string) – a logger name
возвращает:

a logger instance

Example

This example shows how to set the verbose level for module1 and the error level for module2 in a configuration file:

log:
  modules:
    module1: 'verbose'
    module2: 'error'
app:
  file: 'app.lua'

To create the module1 and module2 loggers in your application (app.lua), call the new() function:

-- Creates new loggers --
module1_log = require('log').new('module1')
module2_log = require('log').new('module2')

Then, you can call functions corresponding to different logging levels to make sure that events with severities above or equal to the given levels are shown:

-- Prints 'info' messages --
module1_log.info('Info message from module1')
--[[
[16300] main/103/interactive/module1 I> Info message from module1
---
...
--]]

-- Swallows 'debug' messages --
module1_log.debug('Debug message from module1')
--[[
---
...
--]]

-- Swallows 'info' messages --
module2_log.info('Info message from module2')
--[[
---
...
--]]

At the same time, the events with severities below the specified levels are swallowed.

Example on GitHub: log_new_modules.

Модуль merger

Общие сведения

The merger module takes a stream of tuples and provides access to them as tables.

Указатель

The four functions for creating a merger object instance are:

The methods for using a merger object are:

merger.new_tuple_source(gen, param, state)

Create a new merger instance from a tuple source.

A tuple source just returns one tuple.

The generator function gen() allows creation of multiple tuples via an iterator.

The gen() function should return:

  • state, tuple each time it is called and a new tuple is available,
  • nil when no more tuples are available.
Параметры:
  • gen – function for iteratively returning tuples
  • param – parameter for the gen function
возвращает:

merger-object a merger object

Example: see merger_object:pairs() method.

merger.new_buffer_source(gen, param, state)

Create a new merger instance from a buffer source.

Parameters and return: same as for merger.new_tuple_source.

To set up a buffer, or a series of buffers, use the buffer module.

merger.new_table_source(gen, param, state)

Create a new merger instance from a table source.

Parameters and return: same as for merger.new_tuple_source.

Example: see merger_object:select() method.

merger.new(key_def, sources, options)

Create a new merger instance from a merger source.

A merger source is created from a key_def object and a set of (tuple or buffer or table or merger) sources. It performs a kind of merge sort. It chooses a source with a minimal / maximal tuple on each step, consumes a tuple from this source, and repeats.

Параметры:
  • key_def – object created with key_def
  • source – parameter for the gen() function
  • options – reverse=true if descending, false or nil if ascending
возвращает:

merger-object a merger object

A key_def can be cached across requests with the same ordering rules (typically these would be requests accessing the same space).

Example: see merger_object:pairs() method.

object merger_object

A merger object is an object returned by:

It has methods:

merger_object:select([buffer[, limit]])

Access the contents of a merger object with familiar select syntax.

Параметры:
возвращает:

a table of tuples, similar to what select would return

Example with new_table_source():

-- Source via new_table_source, simple generator function
-- tarantool> s:select()
-- ---
-- - - [100]
--   - [200]
-- ...
merger=require('merger')
k=0
function merger_function(param)
  k = k + 1
  if param[k] == nil then return nil end
  return box.NULL, param[k]
  end
chunks={}
chunks[1] = {{100}} chunks[2] = {{200}} chunks[3] = nil
s = merger.new_table_source(merger_function, chunks)
s:select()
merger_object:pairs()

The pairs() method (or the equivalent ipairs() alias method) returns a luafun iterator. It is a Lua iterator, but also provides a set of handy methods to operate in functional style.

Параметры:
  • tuple (table) – tuple or Lua table with field contents
возвращает:

the tuples that can be found with a standard pairs() function

Example with new_tuple_source():

-- Source via new_tuple_source, from a space of tables
-- The result will look like this:
-- tarantool> so:pairs():totable()
-- ---
-- - - [100]
--   - [200]
-- ...
merger = require('merger')
box.schema.space.create('s')
box.space.s:create_index('i')
box.space.s:insert({100})
box.space.s:insert({200})
so = merger.new_tuple_source(box.space.s:pairs())
so:pairs():totable()

Example with two mergers:

-- Source via key_def, and table data

-- Create the key_def object
merger = require('merger')
key_def_lib = require('key_def')
key_def = key_def_lib.new({{
    fieldno = 1,
    type = 'string',
}})
-- Create the table source
data = {{'a'}, {'b'}, {'c'}}
source = merger.new_source_fromtable(data)
i1 = merger.new(key_def, {source}):pairs()
i2 = merger.new(key_def, {source}):pairs()
-- t1 will be 'a' (tuple 1 from merger 1)
t1 = i1:head():totable()
-- t3 will be 'c' (tuple 3 from merger 2)
t3 = i2:head():totable()
-- t2 will be 'b' (tuple 2 from merger 1)
t2 = i1:head():totable()
-- i1:is_null() will be true (merger 1 ends)
i1:is_null()
-- i2:is_null() will be true (merger 2 ends)
i2:is_null()

More examples:

See https://github.com/Totktonada/tarantool-merger-examples which, in addition to discussing the merger API in detail, shows Lua code for handling many more situations than are in this manual’s brief examples.

Module metrics

Since: 2.11.1

The metrics module provides the ability to collect and expose Tarantool metrics.

Примечание

If you use a Tarantool version below 2.11.1, it is necessary to install the latest version of metrics first. For Tarantool 2.11.1 and above, you can also use the external metrics module. In this case, the external metrics module takes priority over the built-in one.

Overview

Collectors

Tarantool provides the following metric collectors:

A collector is a representation of one or more observations that change over time.

counter

A counter is a cumulative metric that denotes a single monotonically increasing counter. Its value might only increase or be reset to zero on restart. For example, you can use the counter to represent the number of requests served, tasks completed, or errors.

The design is based on the Prometheus counter.

gauge

A gauge is a metric that denotes a single numerical value that can arbitrarily increase and decrease.

The gauge type is typically used for measured values like temperature or current memory usage. It could also be used for values that can increase or decrease, such as the number of concurrent requests.

The design is based on the Prometheus gauge.

histogram

A histogram metric is used to collect and analyze statistical data about the distribution of values within the application. Unlike metrics that track the average value or quantity of events, a histogram provides detailed visibility into the distribution of values and can uncover hidden dependencies.

The design is based on the Prometheus histogram.

summary

A summary metric is used to collect statistical data about the distribution of values within the application.

Each summary provides several measurements:

  • total count of measurements
  • sum of measured values
  • values at specific quantiles

Similar to histograms, the summary also operates with value ranges. However, unlike histograms, it uses quantiles (defined by a number between 0 and 1) for this purpose. In this case, it is not required to define fixed boundaries. For summary type, the ranges depend on the measured values and the number of measurements.

The design is based on the Prometheus summary.

Labels

A label is a piece of metainfo that you associate with a metric in the key-value format. For details, see labels in Prometheus and tags in Graphite.

Labels are used to differentiate between the characteristics of a thing being measured. For example, in a metric associated with the total number of HTTP requests, you can represent methods and statuses as label pairs:

http_requests_total_counter:inc(1, { method = 'POST', status = '200' })

The example above allows extracting the following time series:

  1. The total number of requests over time with method = "POST" (and any status).
  2. The total number of requests over time with status = 500 (and any method).

Configuring metrics

To configure metrics, use metrics.cfg(). This function can be used to turn on or off the specified metrics or to configure labels applied to all collectors. Moreover, you can use the following shortcut functions to set-up metrics or labels:

Примечание

Starting from version 3.0, metrics can be configured using a configuration file in the metrics section.

Custom metrics

Creating custom metrics

To create a custom metric, follow the steps below:

  1. Create a metric

    To create a new metric, you need to call a function corresponding to the desired collector type. For example, call metrics.counter() or metrics.gauge() to create a new counter or gauge, respectively. In the example below, a new counter is created:

    local metrics = require('metrics')
local bands_replace_count = metrics.counter('bands_replace_count', 'The number of data operations')

    This counter is intended to collect the number of data operations performed on the specified space.

    In the next example, a gauge is created:

    local metrics = require('metrics')
local bands_waste_size = metrics.gauge('bands_waste_size', 'The size of memory wasted due to internal fragmentation')

  2. Observe a value

    You can observe a value in two ways:

    • At the appropriate place, for example, in an API request handler or trigger. In this example below, the counter value is increased any time a data operation is performed on the bands space. To increase a counter value, counter_obj:inc() is called.

      local metrics = require('metrics')
local bands_replace_count = metrics.counter('bands_replace_count', 'The number of data operations')
local trigger = require('trigger')
trigger.set(
        'box.space.bands.on_replace',
        'update_bands_replace_count_metric',
        function(_, _, _, request_type)
            bands_replace_count:inc(1, { request_type = request_type })
        end
)

    • At the time of requesting the data collected by metrics. In this case, you need to collect the required metric inside metrics.register_callback(). The example below shows how to use a gauge collector to measure the size of memory wasted due to internal fragmentation:

      local metrics = require('metrics')
local bands_waste_size = metrics.gauge('bands_waste_size', 'The size of memory wasted due to internal fragmentation')
metrics.register_callback(function()
    bands_waste_size:set(box.space.bands:stat()['tuple']['memtx']['waste_size'])
end)

      To set a gauge value, gauge_obj:set() is called.

You can find the full example on GitHub: metrics_collect_custom.

Possible limitations

The module allows to add your own metrics, but there are some subtleties when working with specific tools.

When adding your custom metric, it’s important to ensure that the number of label value combinations is kept to a minimum. Otherwise, combinatorial explosion may happen in the timeseries database with metrics values stored. Examples of data labels:

For example, if your company uses InfluxDB for metric collection, you can potentially disrupt the entire monitoring setup, both for your application and for all other systems within the company. As a result, monitoring data is likely to be lost.

Example:

local some_metric = metrics.counter('some', 'Some metric')

-- THIS IS POSSIBLE
local function on_value_update(instance_alias)
   some_metric:inc(1, { alias = instance_alias })
end

-- THIS IS NOT ALLOWED
local function on_value_update(customer_id)
   some_metric:inc(1, { customer_id = customer_id })
end

In the example, there are two versions of the function on_value_update. The top version labels the data with the cluster instance’s alias. Since there’s a relatively small number of nodes, using them as labels is feasible. In the second case, an identifier of a record is used. If there are many records, it’s recommended to avoid such situations.

The same principle applies to URLs. Using the entire URL with parameters is not recommended. Use a URL template or the name of the command instead.

In essence, when designing custom metrics and selecting labels or tags, it’s crucial to opt for a minimal set of values that can uniquely identify the data without introducing unnecessary complexity or potential conflicts with existing metrics and systems.

Collecting HTTP metrics

The metrics module provides middleware for monitoring HTTP latency statistics for endpoints that are created using the http module. The latency collector observes both latency information and the number of invocations. The metrics collected by HTTP middleware are separated by a set of labels:

For each route that you want to track, you must specify the middleware explicitly. The example below shows how to collect statistics for requests made to the /metrics/hello endpoint.

httpd = require('http.server').new('127.0.0.1', 8080)
local metrics = require('metrics')
metrics.http_middleware.configure_default_collector('summary')
httpd:route({
    method = 'GET',
    path = '/metrics/hello'
}, metrics.http_middleware.v1(
        function()
            return { status = 200,
                     headers = { ['content-type'] = 'text/plain' },
                     body = 'Hello from http_middleware!' }
        end))

httpd:start()

Примечание

The middleware does not cover the 404 errors.

Collecting metrics using plugins

The metrics module provides a set of plugins that let you collect metrics through a unified interface:

For example, you can obtain an HTTP response object containing metrics in the Prometheus format by calling the metrics.plugins.prometheus.collect_http() function:

local prometheus_plugin = require('metrics.plugins.prometheus')
local prometheus_metrics = prometheus_plugin.collect_http()

To expose the collected metrics, you can use the http module:

httpd = require('http.server').new('127.0.0.1', 8080)
httpd:route({
    method = 'GET',
    path = '/metrics/prometheus'
}, function()
    local prometheus_plugin = require('metrics.plugins.prometheus')
    local prometheus_metrics = prometheus_plugin.collect_http()
    return prometheus_metrics
end)
httpd:start()

Example on GitHub: metrics_plugins

Creating custom plugins

Use the following API to create custom plugins:

To create a plugin, you need to include the following in your main export function:

-- Invoke all callbacks registered via `metrics.register_callback(<callback-function>)`
metrics.invoke_callbacks()

-- Loop over collectors
for _, c in pairs(metrics.collectors()) do
    ...

    -- Loop over instant observations in the collector
    for _, obs in pairs(c:collect()) do
        -- Export observation `obs`
        ...
    end
end

See the source code of built-in plugins in the metrics GitHub repository.

API Reference

metrics API  
metrics.cfg() Entrypoint to setup the module
metrics.collect() Collect observations from each collector
metrics.collectors() List all collectors in the registry
metrics.counter() Register a new counter
metrics.enable_default_metrics() Same as metrics.cfg{ include = include, exclude = exclude }
metrics.gauge() Register a new gauge
metrics.histogram() Register a new histogram
metrics.invoke_callbacks() Invoke all registered callbacks
metrics.register_callback() Register a function named callback
metrics.set_global_labels() Same as metrics.cfg{ labels = label_pairs }
metrics.summary() Register a new summary
metrics.unregister_callback() Unregister a function named callback
metrics.http_middleware API  
metrics.http_middleware.build_default_collector() Register and return a collector for the middleware
metrics.http_middleware.configure_default_collector() Register a collector for the middleware and set it as default
metrics.http_middleware.get_default_collector() Get the default collector
metrics.http_middleware.set_default_collector() Set the default collector
metrics.http_middleware.v1() Latency measuring wrap-up
Related objects  
collector_object A collector object
counter_obj A counter object
gauge_obj A gauge object
histogram_obj A histogram object
registry A metrics registry
summary_obj A summary object

metrics API

metrics.cfg([config])

Entrypoint to setup the module.

Параметры:
  • config (table) –

    module configuration options:

    • cfg.include (string/table, default all): all to enable all supported default metrics, none to disable all default metrics, table with names of the default metrics to enable a specific set of metrics.
    • cfg.exclude (table, default {}): a table containing the names of the default metrics that you want to disable. Has higher priority than cfg.include.
    • cfg.labels (table, default {}): a table containing label names as string keys, label values as values. See also: Labels.

You can work with metrics.cfg as a table to read values, but you must call metrics.cfg{} as a function to update them.

Supported default metric names (for cfg.include and cfg.exclude tables):

  • all (metasection including all metrics)
  • network
  • operations
  • system
  • replicas
  • info
  • slab
  • runtime
  • memory
  • spaces
  • fibers
  • cpu
  • vinyl
  • memtx
  • luajit
  • clock
  • event_loop
  • config

See metrics reference for details. All metric collectors from the collection have metainfo.default = true.

cfg.labels are the global labels to be added to every observation.

Global labels are applied only to metric collection. They have no effect on how observations are stored.

Global labels can be changed on the fly.

label_pairs from observation objects have priority over global labels. If you pass label_pairs to an observation method with the same key as some global label, the method argument value will be used.

Note that both label names and values in label_pairs are treated as strings.

metrics.collect([opts])

Collect observations from each collector.

Параметры:
  • opts (table) –

    table of collect options:

    • invoke_callbacks – if true, invoke_callbacks() is triggered before actual collect.
    • default_only – if true, observations contain only default metrics (metainfo.default = true).
metrics.collectors()

List all collectors in the registry. Designed to be used in exporters.

Return:A list of created collectors (see collector_object).

See also: Creating custom plugins

metrics.counter(name[, help, metainfo])

Register a new counter.

Параметры:
  • name (string) – collector name. Must be unique.
  • help (string) – collector description.
  • metainfo (table) – collector metainfo.
Return:

A counter object (see counter_obj).
Rtype:

counter_obj

See also: Creating custom metrics

metrics.enable_default_metrics([include, exclude])

Same as metrics.cfg{include=include, exclude=exclude}, but include={} is treated as include='all' for backward compatibility.

metrics.gauge(name[, help, metainfo])

Register a new gauge.

Параметры:
  • name (string) – collector name. Must be unique.
  • help (string) – collector description.
  • metainfo (table) – collector metainfo.
Return:

A gauge object (see gauge_obj).
Rtype:

gauge_obj

See also: Creating custom metrics

metrics.histogram(name[, help, buckets, metainfo])

Register a new histogram.

Параметры:
  • name (string) – collector name. Must be unique.
  • help (string) – collector description.
  • buckets (table) – histogram buckets (an array of sorted positive numbers). The infinity bucket (INF) is appended automatically. Default: {.005, .01, .025, .05, .075, .1, .25, .5, .75, 1.0, 2.5, 5.0, 7.5, 10.0, INF}.
  • metainfo (table) – collector metainfo.
Return:

A histogram object (see histogram_obj).
Rtype:

histogram_obj

See also: Creating custom metrics

Примечание

A histogram is basically a set of collectors:

  • name .. "_sum" – a counter holding the sum of added observations.
  • name .. "_count" – a counter holding the number of added observations.
  • name .. "_bucket" – a counter holding all bucket sizes under the label le (less or equal). To access a specific bucket – x (where x is a number), specify the value x for the label le.
metrics.invoke_callbacks()

Invoke all registered callbacks. Has to be called before each collect(). You can also use collect{invoke_callbacks = true} instead. If you’re using one of the default exporters, invoke_callbacks() will be called by the exporter.

See also: Creating custom plugins

metrics.register_callback(callback)

Register a function named callback, which will be called right before metric collection on plugin export.

Параметры:
  • callback (function) – a function that takes no parameters.

This method is most often used for gauge metrics updates.

Example:

local metrics = require('metrics')
local bands_waste_size = metrics.gauge('bands_waste_size', 'The size of memory wasted due to internal fragmentation')
metrics.register_callback(function()
    bands_waste_size:set(box.space.bands:stat()['tuple']['memtx']['waste_size'])
end)

See also: Custom metrics

metrics.set_global_labels(label_pairs)

Same as metrics.cfg{ labels = label_pairs }. Learn more in metrics.cfg().

metrics.summary(name[, help, objectives, params, metainfo])

Register a new summary. Quantile computation is based on the «Effective computation of biased quantiles over data streams» algorithm.

Параметры:
  • name (string) – collector name. Must be unique.
  • help (string) – collector description.
  • objectives (table) – a list of «targeted» φ-quantiles in the {quantile = error, ... } form. Example: {[0.5]=0.01, [0.9]=0.01, [0.99]=0.01}. The targeted φ-quantile is specified in the form of a φ-quantile and the tolerated error. For example, {[0.5] = 0.1} means that the median (= 50th percentile) is to be returned with a 10-percent error. Note that percentiles and quantiles are the same concept, except that percentiles are expressed as percentages. The φ-quantile must be in the interval [0, 1]. A lower tolerated error for a φ-quantile results in higher memory and CPU usage during summary calculation.
  • params (table) – table of the summary parameters used to configuring the sliding time window. This window consists of several buckets to store observations. New observations are added to each bucket. After a time period, the head bucket (from which observations are collected) is reset, and the next bucket becomes the new head. This way, each bucket stores observations for max_age_time * age_buckets_count seconds before it is reset. max_age_time sets the duration of each bucket’s lifetime – that is, how many seconds the observations are kept before they are discarded. age_buckets_count sets the number of buckets in the sliding time window. This variable determines the number of buckets used to exclude observations older than max_age_time from the summary. The value is a trade-off between resources (memory and CPU for maintaining the bucket) and how smooth the time window moves. Default value: {max_age_time = math.huge, age_buckets_count = 1}.
  • metainfo (table) – collector metainfo.
Return:

A summary object (see summary_obj).
Rtype:

summary_obj

See also: Creating custom metrics

Примечание

A summary represents a set of collectors:

  • name .. "_sum" – a counter holding the sum of added observations.
  • name .. "_count" – a counter holding the number of added observations.
  • name holds all the quantiles under observation that find themselves under the label quantile (less or equal). To access bucket x (where x is a number), specify the value x for the label quantile.
metrics.unregister_callback(callback)

Unregister a function named callback that is called right before metric collection on plugin export.

Параметры:
  • callback (function) – a function that takes no parameters.

Example:

local cpu_callback = function()
    local cpu_metrics = require('metrics.psutils.cpu')
    cpu_metrics.update()
end

metrics.register_callback(cpu_callback)

-- after a while, we don't need that callback function anymore

metrics.unregister_callback(cpu_callback)

metrics.http_middleware API

metrics.http_middleware.build_default_collector(type_name, name[, help])

Register and return a collector for the middleware.

Параметры:
  • type_name (string) – collector type: histogram or summary. The default is histogram.
  • name (string) – collector name. The default is http_server_request_latency.
  • help (string) – collector description. The default is HTTP Server Request Latency.
Return:

A collector object

Possible errors:

  • A collector with the same type and name already exists in the registry.
metrics.http_middleware.configure_default_collector(type_name, name, help)

Register a collector for the middleware and set it as default.

Параметры:
  • type_name (string) – collector type: histogram or summary. The default is histogram.
  • name (string) – collector name. The default is http_server_request_latency.
  • help (string) – collector description. The default is HTTP Server Request Latency.

Possible errors:

  • A collector with the same type and name already exists in the registry.
metrics.http_middleware.get_default_collector()

Return the default collector. If the default collector hasn’t been set yet, register it (with default http_middleware.build_default_collector() parameters) and set it as default.

Return:A collector object
metrics.http_middleware.set_default_collector(collector)

Set the default collector.

Параметры:
  • collector – middleware collector object
metrics.http_middleware.v1(handler, collector)

Latency measuring wrap-up for the HTTP ver. 1.x.x handler. Returns a wrapped handler.

Learn more in Collecting HTTP metrics.

Параметры:

Usage:

httpd:route(route, http_middleware.v1(request_handler, collector))

See also: Collecting HTTP metrics

metrics.plugins.prometheus

metrics.plugins.prometheus.collect_http()

Get an HTTP response object containing metrics in the Prometheus format.

Return:

a table containing the following fields:

  • status: set to 200
  • headers: response headers
  • body: metrics in the Prometheus format
Rtype:

table

Example

local prometheus_plugin = require('metrics.plugins.prometheus')
local prometheus_metrics = prometheus_plugin.collect_http()

Example on GitHub: metrics_plugins

metrics.plugins.graphite

metrics.plugins.graphite.init(options)

Send all metrics to a remote Graphite server. Exported metric names are formatted as follows: <prefix>.<metric_name>.

Параметры:
  • options (table) –

    possible options:

    • prefix (string): metrics prefix ('tarantool' by default)
    • host (string): Graphite server host ('127.0.0.1' by default)
    • port (number): Graphite server port (2003 by default)
    • send_interval (number): metrics collection interval in seconds (2 by default)

Example

local graphite_plugin = require('metrics.plugins.graphite')
graphite_plugin.init {
    prefix = 'tarantool',
    host = '127.0.0.1',
    port = 2003,
    send_interval = 1,
}

metrics.plugins.json

metrics.plugins.json.export()

Export metrics in the JSON format.

Return:a string containing metrics in the JSON format
Rtype:string

Важно

The values can also be +-math.huge and math.huge * 0. In such case:

  • math.huge is serialized to "inf"
  • -math.huge is serialized to "-inf"
  • math.huge * 0 is serialized to "nan".

Example

local json_plugin = require('metrics.plugins.json')
local json_metrics = json_plugin.export()

Example on GitHub: metrics_plugins

Модуль msgpack

Общие сведения

The msgpack module decodes raw MsgPack strings by converting them to Lua objects, and encodes Lua objects by converting them to raw MsgPack strings. Tarantool makes heavy internal use of MsgPack because tuples in Tarantool are stored as MsgPack arrays.

Besides, starting from version 2.10.0, the msgpack module enables creating a specific userdata Lua object – MsgPack object. The MsgPack object stores arbitrary MsgPack data, and can be created from any Lua object including another MsgPack object and from a raw MsgPack string. The MsgPack object has its own set of methods and iterators.

Примечание

  • MsgPack is short for MessagePack.
  • A «raw MsgPack string» is a byte array formatted according to the MsgPack specification including type bytes and sizes. The type bytes and sizes can be made displayable with string.hex(), or the raw MsgPack strings can be converted to Lua objects by using the msgpack module methods.

API Reference

Below is a list of msgpack members and related objects.

Members  
msgpack.encode(lua_value) Convert a Lua object to a raw MsgPack string
msgpack.encode(lua_value,ibuf) Convert a Lua object to a raw MsgPack string in an ibuf
msgpack.decode(msgpack_string) Convert a raw MsgPack string to a Lua object
msgpack.decode(C_style_string_pointer) Convert a raw MsgPack string in an ibuf to a Lua object
msgpack.decode_unchecked(msgpack_string) Convert a raw MsgPack string to a Lua object
msgpack.decode_unchecked(C_style_string_pointer) Convert a raw MsgPack string to a Lua object
msgpack.decode_array_header(byte-array, size) Call the MsgPuck’s mp_decode_array function and return the array size and a pointer to the first array component
msgpack.decode_map_header(byte-array, size) Call the MsgPuck’s mp_decode_map function and return the map size and a pointer to the first map component
__serialize parameter Output structure specification
msgpack.cfg() Change MsgPack configuration settings
msgpack.NULL Analog of Lua’s nil
msgpack.object(lua_value) Create a MsgPack object from a Lua object
msgpack.object_from_raw(msgpack_string) Create a MsgPack object from a raw MsgPack string
msgpack.object_from_raw(C_style_string_pointer, size) Create a MsgPack object from a raw MsgPack string
msgpack.is_object(some_argument) Check if an argument is a MsgPack object
Related objects  
msgpack_object A MsgPack object
iterator_object A MsgPack iterator object

Members

msgpack.encode(lua_value)

Convert a Lua object to a raw MsgPack string.

Параметры:
  • lua_value – скалярное значение или значение из Lua-таблицы.
возвращает:

the original contents formatted as a raw MsgPack string;
тип возвращаемого значения:
 

raw MsgPack string
msgpack.encode(lua_value, ibuf)

Convert a Lua object to a raw MsgPack string in an ibuf, which is a buffer such as buffer.ibuf() creates. As with encode(lua_value), the result is a raw MsgPack string, but it goes to the ibuf output instead of being returned.

Параметры:
  • lua_value (lua-object) – скалярное значение или значение из Lua-таблицы.
  • ibuf (buffer) – (output parameter) where the result raw MsgPack string goes
возвращает:

number of bytes in the output
тип возвращаемого значения:
 

raw MsgPack string

Example using buffer.ibuf() and ffi.string() and string.hex(): The result will be „91a161“ because 91 is the MessagePack encoding of «fixarray size 1», a1 is the MessagePack encoding of «fixstr size 1», and 61 is the UTF-8 encoding of „a“:

ibuf = require('buffer').ibuf()
msgpack_string_size = require('msgpack').encode({'a'}, ibuf)
msgpack_string = require('ffi').string(ibuf.rpos, msgpack_string_size)
string.hex(msgpack_string)
msgpack.decode(msgpack_string[, start_position])

Convert a raw MsgPack string to a Lua object.

Параметры:
  • msgpack_string (string) – a raw MsgPack string.
  • start_position (integer) – откуда начинать, минимальное значение = 1, максимальное = длина строки, по умолчанию = 1.
возвращает:
  • (if msgpack_string is a valid raw MsgPack string) the original contents of msgpack_string, formatted as a Lua object, usually a Lua table, (otherwise) a scalar value, such as a string or a number;
  • «next_start_position». Если расшифровка decode останавливается после разбора байта N в msgpack_string, то «next_start_position» = N + 1, а decode(msgpack_string, next_start_position) продолжит разбор с места остановки предыдущего decode плюс 1. Как правило, decode разбирает всю строку msgpack_string, поэтому «next_start_position» будет равняться string.len(msgpack_string) + 1.
тип возвращаемого значения:
 

Lua object and number

Example: The result will be [„a“] and 4:

msgpack_string = require('msgpack').encode({'a'})
require('msgpack').decode(msgpack_string, 1)
msgpack.decode(C_style_string_pointer, size)

Convert a raw MsgPack string, whose address is supplied as a C-style string pointer such as the rpos pointer which is inside an ibuf such as buffer.ibuf() creates, to a Lua object. A C-style string pointer may be described as cdata<char *> or cdata<const char *>.

Параметры:
  • C_style_string_pointer (buffer) – a pointer to a raw MsgPack string.
  • size (integer) – number of bytes in the raw MsgPack string
возвращает:
  • (if C_style_string_pointer points to a valid raw MsgPack string) the original contents of msgpack_string, formatted as a Lua object, usually a Lua table, (otherwise) a scalar value, such as a string or a number;
  • returned_pointer = a C-style pointer to the byte after what was passed, so that C_style_string_pointer + size = returned_pointer
тип возвращаемого значения:
 

table and C-style pointer to after what was passed

Example using buffer.ibuf and pointer arithmetic: The result will be [„a“] and 3 and true:

ibuf = require('buffer').ibuf()
msgpack_string_size = require('msgpack').encode({'a'}, ibuf)
a, b = require('msgpack').decode(ibuf.rpos, msgpack_string_size)
a, b - ibuf.rpos, msgpack_string_size == b - ibuf.rpos
msgpack.decode_unchecked(msgpack_string[, start_position])

Input and output are the same as for decode(string).

msgpack.decode_unchecked(C_style_string_pointer)

Input and output are the same as for decode(C_style_string_pointer), except that size is not needed. Some checking is skipped, and decode_unchecked(C_style_string_pointer) can operate with string pointers to buffers which decode(C_style_string_pointer) cannot handle. For an example see the buffer module.

msgpack.decode_array_header(byte-array, size)

Call the MsgPuck’s mp_decode_array function and return the array size and a pointer to the first array component. A subsequent call to msgpack_decode can decode the component instead of the whole array.

Параметры:
  • byte-array – a pointer to a raw MsgPack string.
  • size – a number greater than or equal to the string’s length
возвращает:
  • the size of the array;
  • a pointer to after the array header.

Example:

-- Example of decode_array_header
-- Suppose we have the raw data '\x93\x01\x02\x03'.
-- \x93 is MsgPack encoding for a header of a three-item array.
-- We want to skip it and decode the next three items.
msgpack = require('msgpack');
ffi = require('ffi');
x, y = msgpack.decode_array_header(ffi.cast('char*', '\x93\x01\x02\x03'), 4)
a = msgpack.decode(y, 1);
b = msgpack.decode(y + 1, 1);
c = msgpack.decode(y + 2, 1);
a, b, c
-- The result is: 1,2,3.
msgpack.decode_map_header(byte-array, size)

Call the MsgPuck’s mp_decode_map function and return the map size and a pointer to the first map component. A subsequent call to msgpack_decode can decode the component instead of the whole map.

Параметры:
  • byte-array – a pointer to a raw MsgPack string.
  • size – a number greater than or equal to the raw MsgPack string’s length
возвращает:
  • the size of the map;
  • a pointer to after the map header.

Example:

-- Example of decode_map_header
-- Suppose we have the raw data '\x81\xa2\x41\x41\xc3'.
-- '\x81' is MsgPack encoding for a header of a one-item map.
-- We want to skip it and decode the next map item.
msgpack = require('msgpack');
ffi = require('ffi')
x, y = msgpack.decode_map_header(ffi.cast('char*', '\x81\xa2\x41\x41\xc3'), 5)
a = msgpack.decode(y, 3);
b = msgpack.decode(y + 3, 1)
x, a, b
-- The result is: 1,"AA", true.

__serialize parameter

The MsgPack output structure can be specified with the __serialize parameter:

  • „seq“, „sequence“, „array“ – table encoded as an array
  • „map“, „mappping“ – table encoded as a map
  • function – the meta-method called to unpack the serializable representation of table, cdata, or userdata objects

Serializing „A“ and „B“ with different __serialize values brings different results. To show this, here is a routine which encodes {'A','B'} both as an array and as a map, then displays each result in hexadecimal.

function hexdump(bytes)
    local result = ''
    for i = 1, #bytes do
        result = result .. string.format("%x", string.byte(bytes, i)) .. ' '
    end
    return result
end

msgpack = require('msgpack')
m1 = msgpack.encode(setmetatable({'A', 'B'}, {
                             __serialize = "seq"
                          }))
m2 = msgpack.encode(setmetatable({'A', 'B'}, {
                             __serialize = "map"
                          }))
print('array encoding: ', hexdump(m1))
print('map encoding: ', hexdump(m2))

Результат:

**array** encoding: 92 a1 41 a1 42
**map** encoding:   82 01 a1 41 02 a1 42

The MsgPack Specification page explains that the first encoding means:

fixarray(2), fixstr(1), "A", fixstr(1), "B"

а значение второго результата кодирования:

fixmap(2), key(1), fixstr(1), "A", key(2), fixstr(2), "B"

Ниже приведены примеры всех стандартных типов: слева отображение в Lua-таблице, а справа – имя и кодировка в формате MsgPack.

Стандартные типы в MsgPack-кодировке

{} „fixmap“ = 80, если метатаблица – ассоциативный массив „map“, в противном случае, „fixarray“ = 90
„a“ „fixstr“ = a1 61
false „false“ = c2
true „true“ = c3
127 „positive fixint“ = 7f
65535 „uint 16“ = cd ff ff
4294967295 „uint 32“ = ce ff ff ff ff
nil „nil“ = c0
msgpack.NULL то же, что и nil
[0] = 5 „fixmap(1)“ + „positive fixint“ (для ключа) + „positive fixint“ (для значения) = 81 00 05
[0] = nil „fixmap(0)“ = 80 – nil не хранится, если это отсутствующее значение ассоциативного массива
1,5 „float 64“ = cb 3f f8 00 00 00 00 00 00
msgpack.cfg(table)

Change MsgPack configuration settings.

The values are all either integers or boolean true/false.

Характеристика Значение по умолчанию Назначение
cfg.encode_max_depth 128 The maximum recursion depth for encoding
cfg.encode_deep_as_nil false Specify whether to crop tables with nesting level deeper than cfg.encode_max_depth. Not-encoded fields are replaced with one null. If not set, too high nesting is considered an error.
cfg.encode_invalid_numbers true Specify whether to enable encoding of NaN and Inf numbers
cfg.encode_load_metatables true Specify whether the serializer will follow __serialize metatable field
cfg.encode_use_tostring false Specify whether to use tostring() for unknown types
cfg.encode_invalid_as_nil false Specify whether to use NULL for non-recognized types
cfg.encode_sparse_convert true Specify whether to handle excessively sparse arrays as maps. See detailed description below
cfg.encode_sparse_ratio 2 1/encode_sparse_ratio is the permissible percentage of missing values in a sparse array
cfg.encode_sparse_safe 10 A limit ensuring that small Lua arrays are always encoded as sparse arrays (instead of generating an error or encoding as a map)
cfg.encode_error_as_ext true

Specify how error objects (box.error.new()) are encoded in the MsgPack format:

  • if true, errors are encoded as the the MP_ERROR MsgPack extension.
  • if false, the encoding format depends on other configuration options (encode_load_metatables, encode_use_tostring, encode_invalid_as_nil).
cfg.decode_invalid_numbers true Specify whether to enable decoding of NaN and Inf numbers
cfg.decode_save_metatables true Specify whether to set metatables for all arrays and maps

Sparse arrays features

During encoding, the MsgPack encoder tries to classify tables into one of four kinds:

  • map - at least one table index is not unsigned integer
  • regular array - all array indexes are available
  • sparse array - at least one array index is missing
  • excessively sparse array - the number of values missing exceeds the configured ratio

An array is excessively sparse when all the following conditions are met:

  • encode_sparse_ratio > 0
  • max(table) > encode_sparse_safe
  • max(table) > count(table) * encode_sparse_ratio

MsgPack encoder never considers an array to be excessively sparse when encode_sparse_ratio = 0. The encode_sparse_safe limit ensures that small Lua arrays are always encoded as sparse arrays. By default, attempting to encode an excessively sparse array generates an error. If encode_sparse_convert is set to true, excessively sparse arrays will be handled as maps.

msgpack.cfg() example 1:

If msgpack.cfg.encode_invalid_numbers = true (the default), then NaN and Inf are legal values. If that is not desirable, then ensure that msgpack.encode() does not accept them, by saying msgpack.cfg{encode_invalid_numbers = false}, thus:

tarantool> msgpack = require('msgpack'); msgpack.cfg{encode_invalid_numbers = true}
---
...
tarantool> msgpack.decode(msgpack.encode{1, 0 / 0, 1 / 0, false})
---
- [1, -nan, inf, false]
- 22
...
tarantool> msgpack.cfg{encode_invalid_numbers = false}
---
...
tarantool> msgpack.decode(msgpack.encode{1, 0 / 0, 1 / 0, false})
---
- error: ... number must not be NaN or Inf'
...

msgpack.cfg() example 2:

To avoid generating errors on attempts to encode unknown data types as userdata/cdata, you can use this code:

tarantool> httpc = require('http.client').new()
---
...

tarantool> msgpack.encode(httpc.curl)
---
- error: unsupported Lua type 'userdata'
...

tarantool> msgpack.cfg{encode_use_tostring = true}
---
...

tarantool> msgpack.encode(httpc.curl)
---
- !!binary tnVzZXJkYXRhOiAweDAxMDU5NDQ2Mzg=
...

Примечание

To achieve the same effect for only one call to msgpack.encode() (that is without changing the configuration permanently), you can use msgpack.new({encode_invalid_numbers = true}).encode({1, 2}).

Similar configuration settings exist for JSON and YAML.

msgpack.NULL

Значение, сопоставимое с нулевым значением «nil» в языке Lua, которое можно использовать в качестве объекта-заполнителя в кортеже.

Пример:

tarantool> msgpack = require('msgpack')
---
...
tarantool> y = msgpack.encode({'a',1,'b',2})
---
...
tarantool> z = msgpack.decode(y)
---
...
tarantool> z[1], z[2], z[3], z[4]
---
- a
- 1
- b
- 2
...
tarantool> box.space.tester:insert{20, msgpack.NULL, 20}
---
- [20, null, 20]
...
msgpack.object(lua_value)

Since: 2.10.0

Encode an arbitrary Lua object into the MsgPack format.

Параметры:
  • lua_value (lua-object) – a Lua object of any type.
возвращает:

encoded MsgPack data encapsulated in a MsgPack object.
тип возвращаемого значения:
 

userdata

Example:

local msgpack = require('msgpack')

-- Create a MsgPack object from a Lua object of any type
local mp_from_number = msgpack.object(123)
local mp_from_string = msgpack.object('hello world')
local mp_from_array = msgpack.object({ 10, 20, 30 })
local mp_from_table = msgpack.object({ band_name = 'The Beatles', year = 1960 })
local mp_from_tuple = msgpack.object(box.tuple.new{1, 'The Beatles', 1960})
msgpack.object_from_raw(msgpack_string)

Since: 2.10.0

Create a MsgPack object from a raw MsgPack string.

Параметры:
  • msgpack_string (string) – a raw MsgPack string.
возвращает:

a MsgPack object
тип возвращаемого значения:
 

userdata

Example:

local msgpack = require('msgpack')

-- Create a MsgPack object from a raw MsgPack string
local raw_mp_string = msgpack.encode({ 10, 20, 30 })
local mp_from_mp_string = msgpack.object_from_raw(raw_mp_string)
msgpack.object_from_raw(C_style_string_pointer, size)

Since: 2.10.0

Create a MsgPack object from a raw MsgPack string. The address of the MsgPack string is supplied as a C-style string pointer such as the rpos pointer inside an ibuf that the buffer.ibuf() creates. A C-style string pointer may be described as cdata<char *> or cdata<const char *>.

Параметры:
  • C_style_string_pointer (buffer) – a pointer to a raw MsgPack string.
  • size (integer) – number of bytes in the raw MsgPack string.
возвращает:

a MsgPack object
тип возвращаемого значения:
 

userdata

Example:

local msgpack = require('msgpack')

-- Create a MsgPack object from a raw MsgPack string using buffer
local buffer = require('buffer')
local ibuf = buffer.ibuf()
msgpack.encode({ 10, 20, 30 }, ibuf)
local mp_from_mp_string_pt = msgpack.object_from_raw(ibuf.buf, ibuf:size())
msgpack.is_object(some_argument)

Since: 2.10.0

Check if the given argument is a MsgPack object.

Параметры:
  • some_agrument – any argument.
возвращает:

true if the argument is a MsgPack object; otherwise, false
тип возвращаемого значения:
 

boolean

Example:

local msgpack = require('msgpack')

local mp_from_string = msgpack.object('hello world')

-- Check if the given argument is a MsgPack object
local mp_is_object = msgpack.is_object(mp_from_string) -- Returns true
local string_is_object = msgpack.is_object('hello world') -- Returns false

Модуль net.box

The net.box module contains connectors to remote database systems. One variant is for connecting to MySQL or MariaDB or PostgreSQL (see SQL DBMS modules reference). The other variant, which is discussed in this section, is for connecting to Tarantool server instances via a network.

Connecting to a database using net.box

Examples on GitHub: sample_db, net_box

The tutorial shows how to use net.box to connect to a remote Tarantool instance, perform CRUD operations, and execute stored procedures. For more information about the net.box module API, check Модуль net.box.

Примечание

This tutorial shows how to make CRUD requests to a single-instance Tarantool database. To make requests to a sharded Tarantool cluster with the CRUD module, use its API for CRUD operations.

Sample database configuration

This section describes the configuration of a sample database that allows remote connections:

credentials:
  users:
    sampleuser:
      password: '123456'
      privileges:
      - permissions: [ read, write ]
        spaces: [ bands ]
      - permissions: [ execute ]
        functions: [ get_bands_older_than ]

groups:
  group001:
    replicasets:
      replicaset001:
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'

app:
  file: 'myapp.lua'
  • The configuration contains one instance that listens for incoming requests on the 127.0.0.1:3301 address.
  • sampleuser has privileges to select and modify data in the bands space and execute the get_bands_older_than stored function. This user can be used to connect to the instance remotely.
  • myapp.lua defines the data model and a stored function.

The myapp.lua file looks as follows:

-- Create a space --
box.schema.space.create('bands')

-- Specify field names and types --
box.space.bands:format({
    { name = 'id', type = 'unsigned' },
    { name = 'band_name', type = 'string' },
    { name = 'year', type = 'unsigned' }
})

-- Create indexes --
box.space.bands:create_index('primary', { parts = { 'id' } })
box.space.bands:create_index('band', { parts = { 'band_name' } })
box.space.bands:create_index('year_band', { parts = { { 'year' }, { 'band_name' } } })

-- Create a stored function --
box.schema.func.create('get_bands_older_than', {
    body = [[
    function(year)
        return box.space.bands.index.year_band:select({ year }, { iterator = 'LT', limit = 10 })
    end
    ]]
})

You can find the full example on GitHub: sample_db.

Making net.box requests interactively

To try out net.box requests in the interactive console, start the sample_db application using tt start:

$ tt start sample_db

Then, use the tt run -i command to start an interactive console:

$ tt run -i
Tarantool 3.0.0-entrypoint-1144-geaff238d9
type 'help' for interactive help
tarantool>

In the console, you can create a net.box connection and try out data operations.

Creating a net.box connection

To load the net.box module, use the require() directive:

net_box = require('net.box')
--[[
---
...
]]

To create a connection, pass a database URI to the net_box.connect() method:

conn = net_box.connect('sampleuser:123456@127.0.0.1:3301')
--[[
---
...
]]

connection:ping() can be used to check the connection status:

conn:ping()
--[[
---
- true
...
]]

Then, you can get a space object and perform CRUD operations on it using conn.space.<space_name>.

Примечание

Learn more about performing data operations from the Примеры CRUD-операций section.

Inserting data

In the example below, four tuples are inserted into the bands space:

conn.space.bands:insert({ 1, 'Roxette', 1986 })
--[[
---
- - [1, 'Roxette', 1986]
...
]]
conn.space.bands:insert({ 2, 'Scorpions', 1965 })
--[[
---
- [2, 'Scorpions', 1965]
...
]]
conn.space.bands:insert({ 3, 'Ace of Base', 1987 })
--[[
---
- [3, 'Ace of Base', 1987]
...
]]
conn.space.bands:insert({ 4, 'The Beatles', 1960 })
--[[
---
- [4, 'The Beatles', 1960]
...
]]

Querying data

The example below shows how to get a tuple by the specified primary key value:

conn.space.bands:select({ 1 })
--[[
---
- - [1, 'Roxette', 1986]
...
]]

You can also get a tuple by the value of the specified index as follows:

conn.space.bands.index.band:select({ 'The Beatles' })
--[[
---
- - [4, 'The Beatles', 1960]
...
]]

Updating data

space_object.update() updates a tuple identified by the primary key. This method accepts a full key and an operation to execute:

conn.space.bands:update({ 2 }, { { '=', 'band_name', 'Pink Floyd' } })
--[[
---
- [2, 'Pink Floyd', 1965]
...
]]

space_object.upsert() updates an existing tuple or inserts a new one. In the example below, a new tuple is inserted:

conn.space.bands:upsert({ 5, 'The Rolling Stones', 1962 }, { { '=', 'band_name', 'The Doors' } })
--[[
---
...
]]

In this example, space_object.replace() is used to delete the existing tuple and insert a new one:

conn.space.bands:replace({ 1, 'Queen', 1970 })
--[[
---
- [1, 'Queen', 1970]
...
]]

Deleting data

The space_object.delete() call in the example below deletes a tuple whose primary key value is 5:

conn.space.bands:delete({ 5 })
--[[
---
- [5, 'The Rolling Stones', 1962]
...
]]

Executing stored procedures

To execute a stored procedure, use the connection:call() method:

conn:call('get_bands_older_than', { 1966 })
-- ---
-- - [[2, 'Pink Floyd', 1965], [4, 'The Beatles', 1960]]
-- ...

Closing the connection

The connection:close() method can be used to close the connection when it is no longer needed:

conn:close()
--[[
---
...
]]

Примечание

You can find the example with all the requests above on GitHub: net_box.

Общие сведения

Можно вызвать следующие методы:

Все методы net.box безопасны для файберов, то есть можно безопасно обмениваться и использовать один и тот же объект подключения в нескольких файберах одновременно. Фактически так лучше всего работать в Tarantool. Когда несколько файберов используют одно соединение, все запросы передаются по одному сетевому сокету, но каждый файбер получает правильный ответ. Уменьшение количества активных сокетов снижает затрату ресурсов на системные вызовы и увеличивает общую производительность сервера. Однако, в некоторых случаях отдельного соединения недостаточно — например, когда необходимо отдавать приоритет разным запросам или использовать различные идентификаторы при аутентификации.

В большинстве методов net.box можно использовать последний аргумент {options}, который может быть следующим:

На диаграмме ниже представлены возможные состояния и варианты перехода из одного состояния в другое:

net_states.png

На этой диаграмме:

Указатель

Ниже приведен перечень всех функций модуля net.box.

Имя Назначение
net_box.connect()
net_box.new()
net_box.self		 Создание подключения
conn:ping() Выполнение команды проверки состояния PING
conn:wait_connected() Ожидание активности или закрытия подключения
conn:is_connected() Проверка активности или закрытия подключения
conn:wait_state() Ожидание нужного состояния
conn:close() Закрытие подключения
conn.space.space-name:select{field-value} Выбор одного или нескольких кортежей
conn.space.space-name:get{field-value} Выбор кортежа
conn.space.space-name:insert{field-value} Вставка кортежа
conn.space.space-name:replace{field-value} Вставка или замена кортежа
conn.space.space-name:update{field-value} Обновление кортежа
conn.space.space-name:upsert{field-value} Обновление кортежа
conn.space.space-name:delete{field-value} Удаление кортежа
conn:eval() Оценка и выполнение выражения в строке
conn:call() Вызов хранимой процедуры
conn:watch() Subscribe to events broadcast by a remote host
conn:on_connect() Определение триггера на подключение
conn:on_disconnect() Определение триггера на отключение
conn:on_shutdown() Define a shutdown trigger
conn:on_schema_reload() Определение триггера при изменении схемы
conn:new_stream() Create a stream
stream:begin() Begin a stream transaction
stream:commit() Commit a stream transaction
stream:rollback() Rollback a stream transaction
net_box.connect(URI[, {option[s]}])

Создание нового подключения. Подключение устанавливается по требованию во время первого запроса. Можно повторно установить подключение автоматически после отключения (см. ниже опцию reconnect_after). Возвращается объект conn, который поддерживает методы создания удаленных запросов, таких как select, update или delete.

Параметры:
  • URI (string) – URI объекта подключения
  • options –

    the supported options are shown below:

    • user/password: two options to connect to a remote host other than through URI. For example, instead of connect('username:userpassword@localhost:3301') you can write connect('localhost:3301', {user = 'username', password='userpassword'}).
    • wait_connected: a connection timeout. By default, the connection is blocked until the connection is established, but if you specify wait_connected=false, the connection returns immediately. If you specify this timeout, it will wait before returning (wait_connected=1.5 makes it wait at most 1.5 seconds).

      Примечание

      Если присутствует reconnect_after, wait_connected проигнорирует неустойчивые отказы. Ожидание заканчивается, когда подключение установлено или явным образом закрыто.

    • reconnect_after: a number of seconds to wait before reconnecting. The default value, as with the other connect options, is nil. If reconnect_after is greater than zero, then a net.box instance will attempt to reconnect if a connection is lost or a connection attempt fails. This makes transient network failures transparent to the application. Reconnection happens automatically in the background, so requests that initially fail due to connection drops fail, are transparently retried. The number of retries is unlimited, connection retries are made after any specified interval (for example, reconnect_after=5 means that reconnect attempts are made every 5 seconds). When a connection is explicitly closed or when the Lua garbage collector removes it, then reconnect attempts stop.
    • connect_timeout: a number of seconds to wait before returning «error: Connection timed out».
    • fetch_schema: a boolean option that controls fetching schema changes from the server. Default: true. If you don’t operate with remote spaces, for example, run only call or eval, set fetch_schema to false to avoid fetching schema changes which is not needed in this case.

      Важно

      In connections with fetch_schema == false, remote spaces are unavailable and the on_schema_reload triggers don’t work.

    • required_protocol_version: a minimum version of the IPROTO protocol supported by the server. If the version of the IPROTO protocol supported by the server is lower than specified, the connection will fail with an error message. With required_protocol_version = 1, all connections fail where the IPROTO protocol version is lower than 1.
    • required_protocol_features: specified IPROTO protocol features supported by the server. You can specify one or more net.box features from the table below. If the server does not support the specified features, the connection will fail with an error message. With required_protocol_features = {'transactions'}, all connections fail where the server has transactions: false.
net.box feature Назначение IPROTO feature ID IPROTO versions supporting the feature
streams Requires streams support on the server IPROTO_FEATURE_STREAMS 1 and newer
transactions Requires transactions support on the server IPROTO_FEATURE_TRANSACTIONS 1 and newer
error_extension Requires support for MP_ERROR MsgPack extension on the server IPROTO_FEATURE_ERROR_EXTENSION 2 and newer
watchers Requires remote watchers support on the server IPROTO_FEATURE_WATCHERS 3 and newer

To learn more about IPROTO features, see IPROTO_ID and the IPROTO_FEATURES key.

возвращает:объект подключения
тип возвращаемого значения:
 пользовательские данные

Примеры:

net_box = require('net.box')

conn = net_box.connect('localhost:3301')
conn = net_box.connect('127.0.0.1:3302', {wait_connected = false})
conn = net_box.connect('127.0.0.1:3304', {required_protocol_version = 4, required_protocol_features = {'transactions', 'streams'}, })
net_box.new(URI[, {option[s]}])

new() is a synonym for connect(). It is retained for backward compatibility. For more information, see the description of net_box.connect().

object self

Для локального Tarantool-сервера есть заданный объект всегда установленного подключения под названием net_box.self. Он создан с целью облегчить полиморфное использование API модуля net_box. Таким образом, conn = net_box.connect('localhost:3301') можно заменить на conn = net_box.self.

Однако, есть важно отличие встроенного подключения от удаленного:

  • With the embedded connection, requests which do not modify data do not yield. When using a remote connection, due to the implicit rules any request can yield, and the database state may have changed by the time it regains control.
  • Не учитывается ни один параметр, передаваемый в запросе (is_async, on_push, timeout).
object conn
conn:ping([options])

Выполнение команды проверки состояния PING.

Параметры:
  • options (table) – поддерживается опция timeout=секунды
возвращает:

true (правда), если выполнено, false (ложь) в случае ошибки
тип возвращаемого значения:
 

boolean (логический)

Пример:

net_box.self:ping({timeout = 0.5})
conn:wait_connected([timeout])

Ожидание активности или закрытия подключения.

Параметры:
  • timeout (number) – в секундах
возвращает:

true (правда) при подключении, false (ложь), если не выполнено.
тип возвращаемого значения:
 

boolean (логический)

Пример:

net_box.self:wait_connected()
conn:is_connected()

Проверка активности или закрытия подключения.

возвращает:true (правда) при подключении, false (ложь), если не выполнено.
тип возвращаемого значения:
 boolean (логический)

Пример:

net_box.self:is_connected()
conn:wait_state(state[s][, timeout])

[с 1.7.2] Ожидание нужного состояния.

Параметры:
  • states (string) – необходимое состояние
  • timeout (number) – в секундах
возвращает:

true (правда) при подключении, false (ложь) при окончании времени ожидания или закрытии подключения
тип возвращаемого значения:
 

boolean (логический)

Примеры:

-- бесконечное ожидание состояния 'active':
conn:wait_state('active')

-- ожидание в течение максимум 1,5 секунд:
conn:wait_state('active', 1.5)

-- бесконечное ожидание состояния `active` или `fetch_schema`:
conn:wait_state({active=true, fetch_schema=true})
conn:close()

Закрытие подключения.

Объекты подключения удаляются сборщиком мусора в Lua, как и любой другой Lua-объект, поэтому удалять их явным образом необязательно. Однако, поскольку close() представляет собой системный вызов, лучше всего закрыть соединение явным образом, когда оно больше не используется, с целью ускорения работы сборщика мусора.

Пример:

conn:close()
conn.space.<space-name>:select({field-value, ...} [, {options}])

conn.space.имя-спейса:select({...}) – это удаленный вызов, аналогичный локальному вызову box.space.имя-спейса:select{...} (детали). В дополнение см. Модуль buffer и skip-header.

Пример:

conn.space.testspace:select({1,'B'}, {timeout=1})

Примечание

Due to the implicit yield rules a local box.space.space-name:select{...} does not yield, but a remote conn.space.space-name:select{...} call does yield, so global variables or database tuples data may change when a remote conn.space.space-name:select{...} occurs.

conn.space.<space-name>:get({field-value, ...} [, {options}])

conn.space.имя-спейса:get(...) – это удаленный вызов, аналогичный локальному вызову box.space.имя-спейса:get(...) (детали).

Пример:

conn.space.testspace:get({1})
conn.space.<space-name>:insert({field-value, ...} [, {options}])

conn.space.имя-спейса:insert(...) – это удаленный вызов, аналогичный локальному вызову box.space.имя-спейса:insert(...) (детали). В дополнение см. Модуль buffer и skip-header.

Пример:

conn.space.testspace:insert({2,3,4,5}, {timeout=1.1})
conn.space.<space-name>:replace({field-value, ...} [, {options}])

conn.space.имя-спейса:replace(...) – это удаленный вызов, аналогичный локальному вызову box.space.имя-спейса:replace(...) (детали). В дополнение см. Модуль buffer и skip-header.

Пример:

conn.space.testspace:replace({5,6,7,8})
conn.space.<space-name>:update({field-value, ...} [, {options}])

conn.space.имя-спейса:update(...) – это удаленный вызов, аналогичный локальному вызову box.space.имя-спейса:update(...).

Пример:

conn.space.Q:update({1},{{'=',2,5}}, {timeout=0})
conn.space.<space-name>:upsert({field-value, ...} [, {options}])

conn.space.space-name:upsert(...) is the remote-call equivalent of the local call box.space.space-name:upsert(...). (see details). For an additional option see Module buffer and skip-header.

conn.space.<space-name>:delete({field-value, ...} [, {options}])

conn.space.имя-спейса:delete(...) – это удаленный вызов, аналогичный локальному вызову box.space.имя-спейса:delete(...).(детали). В дополнение см. Модуль buffer и skip-header.

conn:eval(Lua-string[, {arguments}[, {options}]])

conn:eval(Lua-строка) оценивает и выполняет выражение в Lua-строке, которое может представлять собой любое выражение или несколько выражений. Требуются права на выполнение; если у пользователя таких прав нет, администратор может их выдать с помощью box.schema.user.grant(имя-пользователя, 'execute', 'universe').

Чтобы гарантировать, что conn:eval вернет то, что возвращает выражение на Lua, начните Lua-строку со слова «return» (вернуть).

Примеры:

tarantool> --Lua-строка
tarantool> conn:eval('function f5() return 5+5 end; return f5();')
---
- 10
...
tarantool> --Lua-строка, {аргументы}
tarantool> conn:eval('return ...', {1,2,{3,'x'}})
---
- 1
- 2
- [3, 'x']
...
tarantool> --Lua-строка, {аргументы}, {парметры}
tarantool> conn:eval('return {nil,5}', {}, {timeout=0.1})
---
- [null, 5]
...
conn:call(function-name[, {arguments}[, {options}]])

conn:call('func', {'1', '2', '3'}) – это удаленный вызов, аналогичный func('1', '2', '3'). Таким образом, conn:call представляет собой удаленный вызов хранимой процедуры. conn:call возвращает то, что возвращает функция.

Ограничение: вызванная функция не может вернуть функцию, например, если func2 определяется как function func2 () return func end, то conn:call(func2) вернет ошибку «error: unsupported Lua type „function“».

Примеры:

tarantool> -- создание 2 функций с conn:eval()
tarantool> conn:eval('function f1() return 5+5 end;')
tarantool> conn:eval('function f2(x,y) return x,y end;')
tarantool> -- вызов первой функции без параметров и опций
tarantool> conn:call('f1')
---
- 10
...
tarantool> -- вызов второй функции с двумя параметрами и одной опцией
tarantool> conn:call('f2',{1,'B'},{timeout=99})
---
- 1
- B
...
conn:watch(key, func)

Subscribe to events broadcast by a remote host.

Параметры:
  • key (string) – a key name of an event to subscribe to
  • func (function) – a callback to invoke when the key value is updated
возвращает:

a watcher handle. The handle consists of one method – unregister(), which unregisters the watcher.

To read more about watchers, see the Functions for watchers section.

The method has the same syntax as the box.watch() function, which is used for subscribing to events locally.

Watchers survive reconnection (see the reconnect_after connection option). All registered watchers are automatically resubscribed when the connection is reestablished.

If a remote host supports watchers, the watchers key will be set in the connection peer_protocol_features. For details, check the net.box features table.

Примечание

Keep in mind that garbage collection of a watcher handle doesn’t lead to the watcher’s destruction. In this case, the watcher remains registered. It is okay to discard the result of watch function if the watcher will never be unregistered.

Example 1:

Server:

-- Broadcast value 42 for the 'foo' key.
box.broadcast('foo', 42)

Client:

conn = net.box.connect(URI)
local log = require('log')
-- Subscribe to updates of the 'foo' key.
w = conn:watch('foo', function(key, value)
    assert(key == 'foo')
    log.info("The box.id value is '%d'", value)
end)

If you don’t need the watcher anymore, you can unregister it using the command below:

w:unregister()

Example 2:

The net.box module provides the ability to monitor updates of a configuration stored in a Tarantool-based configuration storage by watching path or prefix changes. In the example below, conn:watch() is used to monitor updates of a configuration stored by the /myapp/config/all path:

net_box = require('net.box')
local conn = net_box.connect('127.0.0.1:4401')
local log = require('log')
conn:watch('config.storage:/myapp/config/all', function(key, value)
    log.info("Configuration stored by the '/myapp/config/all' key is changed")
end)

You can find the full example here: config_storage.

conn:request(... {is_async=...})

{is_async=true|false} – это опция, которую можно применить во всех запросах net_box, включая conn:call, conn:eval и запросы conn.space.space-name.

По умолчанию, is_async=false, что означает, что запросы будут синхронными для файбера. Файбер блокируется в ожидании ответа на запрос или до истечения времени ожидания. До версии Tarantool 1.10 единственным способом выполнения асинхронных запросов было использование отдельных файберов.

is_async=true означает, что запросы будут асинхронными для файбера. Запрос вызывает передачу управления, но файбер не входит в режим ожидания. Сразу же возвращается результат, но это будет не результат запроса, а объект, который может использовать вызывающая программа для получения результат запроса.

У такого сразу же возвращаемого объекта, который мы называем «future» (будущий), есть собственные методы:

  • future:is_ready() вернет true (правда), если доступен результат запроса,
  • future:result() используется для получения результата запроса (возвращает ответ на запрос или nil в случае, если ответ еще не готов или произошла какая-либо ошибка),
  • future:wait_result(timeout) будет ждать, когда результат запроса будет доступен, а затем получит его или выдаст ошибку, если по истечении времени ожидания результат не получен.
  • future:discard() откажется от объекта.

В обычной ситуации пользователь введет команду future=имя-запроса(...{is_async=true}), а затем либо цикл с проверкой future:is_ready() до тех пор, пока он не вернет true, и получением результата с помощью request_result=future:result(), либо же команду request_result=future:wait_result(...). Возможен вариант, когда клиент проверяет наличие внеполосных сообщений от сервера, вызывая в цикле pairs() – см. box.session.push().

Можно использовать future:discard(), чтобы соединение забыло об ответе – если получен ответ для отброшенного объекта, то он будет проигнорирован, так что размер таблицы запросов будет уменьшен, а другие запросы будут выполняться быстрее.

Примеры:

-- Insert a tuple asynchronously --
tarantool> future = conn.space.bands:insert({10, 'Queen', 1970}, {is_async=true})
---
...
tarantool> future:is_ready()
---
- true
...
tarantool> future:result()
---
- [10, 'Queen', 1970]
...

-- Iterate through a space with 10 records to get data in chunks of 3 records --
tarantool> while true do
               future = conn.space.bands:select({}, {limit=3, after=position, fetch_pos=true, is_async=true})
               result = future:wait_result()
               tuples = result[1]
               position = result[2]
               if position == nil then
                   break
               end
               print('Chunk size: '..#tuples)
           end
Chunk size: 3
Chunk size: 3
Chunk size: 3
Chunk size: 1
---
...

Как правило, {is_async=true} используется только при большой загрузке (более 100 000 запросов в секунду) и большой задержке чтения (более 1 секунды), или же при необходимости отправки нескольких одновременных запросов, которые собирают ответы (что иногда называется «отображение-свертка»).

Примечание

Хотя окончательный результат асинхронного запроса не отличается от результата синхронного запроса, у него другая структура: таблица, а не неупакованные значения.

conn:request(... {return_raw=...})

{return_raw=true} is ignored for:

  • Methods that return nil: begin, commit, rollback, upsert, prepare.
  • index.count (returns number).

For execute, the option is applied only to data (rows). Metadata is decoded even if {return_raw=true}.

Пример:

local c = require('net.box').connect(uri)
local mp = c.eval('eval ...', {1, 2, 3}, {return_raw = true})
mp:decode() -- {1, 2, 3}

The option can be useful if you want to pass a response through without decoding or with partial decoding. The usage of MsgPack object can reduce pressure on the Lua garbage collector.

conn:new_stream()

Create a stream.

Пример:

-- Start a server to create a new stream
local conn = net_box.connect('localhost:3301')
local conn_space = conn.space.test
local stream = conn:new_stream()
local stream_space = stream.space.test
object stream
stream:begin([txn_isolation])

Begin a stream transaction. Instead of the direct method, you can also use the call, eval or execute methods with SQL transaction.

Параметры:
stream:commit()

Commit a stream transaction. Instead of the direct method, you can also use the call, eval or execute methods with SQL transaction.

Примеры:

-- Begin stream transaction
stream:begin()
-- In the previously created ``accounts`` space with the primary key ``test``, modify the fields 2 and 3
stream.space.accounts:update(test_1, {{'-', 2, 370}, {'+', 3, 100}})
-- Commit stream transaction
stream:commit()
stream:rollback()

Rollback a stream transaction. Instead of the direct method, you can also use the call, eval or execute methods with SQL transaction.

Пример:

-- Test rollback for memtx space
space:replace({1})
-- Select return tuple that was previously inserted, because this select belongs to stream transaction
space:select({})
stream:rollback()
-- Select is empty, stream transaction rollback
space:select({})

Триггеры

В модуле net.box можно использовать следующие триггеры:

conn:on_connect([trigger-function[, old-trigger-function]])

Define a trigger for execution when a new connection is established, and authentication and schema fetch are completed due to an event such as net_box.connect.

If a trigger function issues net_box requests, they must be asynchronous ({is_async = true}). An attempt to wait for request completion with future:pairs() or future:wait_result() in the trigger function will result in an error.

If the trigger execution fails and an exception happens, the connection’s state changes to „error“. In this case, the connection is terminated, regardless of the reconnect_after option’s value. Can be called as many times as reconnection happens, if reconnect_after is greater than zero.

Параметры:
  • trigger-function (function) – the trigger function. Takes the conn object as the first argument.
  • old-trigger-function (function) – an existing trigger function to replace with trigger-function
возвращает:

nil или указатель функции
conn:on_disconnect([trigger-function[, old-trigger-function]])

Определение триггера, исполняемого после закрытия соединения. Если функция с триггером вызывает ошибку, то ошибка записывается в журнал, в противном случае записей не будет. Выполнение прекращается после явного закрытия соединения или удаления сборщиком мусора в Lua.

Параметры:
  • trigger-function (function) – the trigger function. Takes the conn object as the first argument
  • old-trigger-function (function) – an existing trigger function to replace with trigger-function
возвращает:

nil или указатель функции
conn:on_shutdown([trigger-function[, old-trigger-function]])

Define a trigger for shutdown when a box.shutdown event is received.

The trigger starts in a new fiber. While the on_shutdown() trigger is running, the connection stays active. It means that the trigger callback is allowed to send new requests.

After the trigger return, the net.box connection goes to the graceful_shutdown state (check the state diagram for details). In this state, no new requests are allowed. The connection waits for all pending requests to be completed.

Once all in-progress requests have been processed, the connection is closed. The state changes to error or error_reconnect (if the reconnect_after option is defined).

Servers that do not support the box.shutdown event or IPROTO_WATCH just close the connection abruptly. In this case, the on_shutdown() trigger is not executed.

Параметры:
  • trigger-function (function) – the trigger function. Takes the conn object as the first argument
  • old-trigger-function (function) – an existing trigger function to replace with trigger-function
возвращает:

nil или указатель функции
conn:on_schema_reload([trigger-function[, old-trigger-function]])

Определение триггера, исполняемого во время выполнения определенной операции на удаленном сервере после обновления схемы. Другими словами, если запрос к серверу не выполняется из-за ошибки несовпадения версии схемы, происходит перезагрузка схемы.

If a trigger function issues net_box requests, they must be asynchronous ({is_async = true}). An attempt to wait for request completion with future:pairs() or future:wait_result() in the trigger function will result in an error.

Параметры:
  • trigger-function (function) – the trigger function. Takes the conn object as the first argument
  • old-trigger-function (function) – an existing trigger function to replace with trigger-function
возвращает:

nil или указатель функции

Примечание

Если указаны параметры (nil, old-trigger-function), старый триггер будет удален.

Если не указан ни один параметр, ответом будет список существующих функций с триггером.

Find the detailed information about triggers in the triggers section.

Модуль os

Общие сведения

Модуль os включает в себя следующие функции: execute(), rename(), getenv(), remove(), date(), exit(), time(), clock(), tmpname(), environ(), setenv(), setlocale(), difftime(). Большинство этих функций описаны в Главе 22 руководства по языку Lua Библиотека функций операционной системы.

Указатель

Ниже приведен перечень всех функций модуля os.

Имя Назначение
os.execute() Выполнение путем передачи в ОС
os.rename() Переименование файла или директории
os.getenv() Получение переменной окружения
os.remove() Удаление файла или директории
os.date() Получение даты в формате
os.exit() Выход из программы
os.time() Получение числа секунд с начала отсчета
os.clock() Получение числа времени ЦП в секундах с момента начала программы
os.tmpname() Получение имени временного файла
os.environ() Получение таблицы со всеми переменными окружения
os.setenv() Определение переменной окружения
os.setlocale() Изменение локали
os.difftime() Получение числа секунд между двумя значениями времени
os.execute(shell-command)

Выполнение путем передачи в ОС.

Параметры:
  • shell-command (string) – что выполнить.

Пример:

tarantool> os.execute('ls -l /usr')
total 200
drwxr-xr-x   2 root root 65536 Apr 22 15:49 bin
drwxr-xr-x  59 root root 20480 Apr 18 07:58 include
drwxr-xr-x 210 root root 65536 Apr 18 07:59 lib
drwxr-xr-x  12 root root  4096 Apr 22 15:49 local
drwxr-xr-x   2 root root 12288 Jan 31 09:50 sbin
---
...
os.rename(old-name, new-name)

Переименование файла или директории.

Параметры:
  • old-name (string) – имя существующего файла или директории,
  • new-name (string) – измененное имя файла или директории.

Пример:

tarantool> os.rename('local','foreign')
---
- null
- 'local: No such file or directory'
- 2
...
os.getenv(variable-name)

Получение переменной окружения.

Параметры: (string) variable-name = имя переменной окружения.

Пример:

tarantool> os.getenv('PATH')
---
- /usr/local/sbin:/usr/local/bin:/usr/sbin
...
os.remove(name)

Удаление файла или директории.

Parameters: (string) name = имя файла или директории, которые будут удалены.

Пример:

tarantool> os.remove('file')
---
- true
...
os.date(format-string[, time-since-epoch])

Возврат даты в формате.

Parameters: (string) format-string = инструкции; (string) time-since-epoch = число секунд с 1970-01-01. Если не указать time-since-epoch, предполагается использование текущего времени.

Пример:

tarantool> os.date("%A %B %d")
---
- Sunday April 24
...
os.exit()

Выход из программы. Если выполняется на экземпляре сервера, останавливается работа экземпляра.

Пример:

tarantool> os.exit()
user@user-shell:~/tarantool_sandbox$
os.time()

Возврат числа секунд с начала отсчета.

Пример:

tarantool> os.time()
---
- 1461516945
...
os.clock()

Возврат числа времени ЦП в секундах с момента начала программы.

Пример:

tarantool> os.clock()
---
- 0.05
...
os.tmpname()

Возврат имени временного файла.

Пример:

tarantool> os.tmpname()
---
- /tmp/lua_7SW1m2
...
os.environ()

Возврат таблицы со всеми переменными окружения.

Пример:

tarantool> os.environ()['TERM']..os.environ()['SHELL']
---
- xterm/bin/bash
...
os.setenv(variable-name, variable-value)

Определение переменной окружения.

Пример:

tarantool> os.setenv('VERSION','99')
---
-
...
os.setlocale([new-locale-string])

Изменение локали. Если не указать new-locale-string, вернется текущая локаль.

Пример:

tarantool> string.sub(os.setlocale(),1,20)
---
- LC_CTYPE=en_US.UTF-8
...
os.difftime(time1, time2)

Возврат числа секунд между двумя значениями времени.

Пример:

tarantool> os.difftime(os.time() - 0)
---
- 1486594859
...

Модуль pickle

Указатель

Ниже приведен перечень всех функций модуля pickle.

Имя Назначение
pickle.pack() Конвертация Lua-переменных в двоичный формат
pickle.unpack() Конвертация Lua-переменных в двоичный формат
pickle.pack(format, argument[, argument ...])

To use Tarantool binary protocol primitives from Lua, it’s necessary to convert Lua variables to binary format. The pickle.pack() helper function is prototyped after Perl pack.

Спецификаторы формата

b, B конвертирует скалярное Lua-значение в 1-байтное целое число и хранит целое число в полученной строке
s, S конвертирует скалярное Lua-значение в 2-байтное целое число и хранит целое число в полученной строке, сначала младший байт
i, I конвертирует скалярное Lua-значение в 4-байтное целое число и хранит целое число в полученной строке, сначала младший байт
l, L конвертирует скалярное Lua-значение в 8-байтное целое число и хранит целое число в полученной строке, сначала младший байт
n конвертирует скалярное Lua-значение в 2-байтное целое число и хранит целое число в полученной строке, порядок от старшего к младшему,
N конвертирует скалярное Lua-значение в 4-байтное целое число и хранит целое число в полученной строке, порядок от старшего к младшему,
q, Q конвертирует скалярное Lua-значение в 8-байтное целое число и хранит целое число в полученной строке, порядок от старшего к младшему,
f конвертирует скалярное Lua-значение в 4-байтное число с плавающей запятой и хранит число с плавающей запятой в полученной строке
d конвертирует скалярное Lua-значение в 8-байтное число двойной точности и хранит число двойной точности в полученной строке
a, A конвертирует скалярное Lua-значение в последовательность байтов и хранит последовательность в полученной строке
Параметры:
  • format (string) – строка со спецификаторами формата
  • argument(s) (scalar-value) – скалярные значения к форматированию
возвращает:

бинарная строка, которая содержит все аргументы, упакованные в соответствии со спецификаторами формата.
тип возвращаемого значения:
 

строка

Скалярное значение может быть либо переменной, либо литеральным значением. Следует помнить, что большие целые числа нужно вводить с tonumber64() или суффиксами LL или ULL.

Возможные ошибки: неизвестный спецификатор формата.

Пример:

tarantool> pickle = require('pickle')
---
...
tarantool> box.space.tester:insert{0, 'hello world'}
---
- [0, 'hello world']
...
tarantool> box.space.tester:update({0}, {{'=', 2, 'bye world'}})
---
- [0, 'bye world']
...
tarantool> box.space.tester:update({0}, {
         >   {'=', 2, pickle.pack('iiA', 0, 3, 'hello')}
         > })
---
- [0, "\0\0\0\0\x03\0\0\0hello"]
...
tarantool> box.space.tester:update({0}, {{'=', 2, 4}})
---
- [0, 4]
...
tarantool> box.space.tester:update({0}, {{'+', 2, 4}})
---
- [0, 8]
...
tarantool> box.space.tester:update({0}, {{'^', 2, 4}})
---
- [0, 12]
...
pickle.unpack(format, binary-string)

Противоположность pickle.pack(). Внимание: если используется спецификатор формата „A“, он должен идти последним.

Параметры:
возвращает:

Список строк или чисел.
тип возвращаемого значения:
 

таблица

Пример:

tarantool> pickle = require('pickle')
---
...
tarantool> tuple = box.space.tester:replace{0}
---
...
tarantool> string.len(tuple[1])
---
- 1
...
tarantool> pickle.unpack('b', tuple[1])
---
- 48
...
tarantool> pickle.unpack('bsi', pickle.pack('bsi', 255, 65535, 4294967295))
---
- 255
- 65535
- 4294967295
...
tarantool> pickle.unpack('ls', pickle.pack('ls', tonumber64('18446744073709551615'), 65535))
---
...
tarantool> num, num64, str = pickle.unpack('slA', pickle.pack('slA', 666,
         > tonumber64('666666666666666'), 'string'))
---
...

Модуль popen

Общие сведения

Начиная с версии 2.4.1 в Tarantool есть встроенный модуль popen, предназначенный для выполнения внешних программ. Он работает аналогично модулю subprocess() в Python или Open3 в Ruby. Однако в popen нет вспомогательных средств, которые предоставляют эти языки; он предоставляет только базовые функции. Для создания объекта popen использует системный вызов vfork(), поэтому вызывающий поток блокируется до тех пор, пока не начинается выполнение дочернего процесса.

В модуле popen есть две функции для создания объекта popen:

Обе функции возвращают дескриптор, который мы будем называть popen_handle или ph. Через дескриптор вы можете выполнять методы.

Указатель

Ниже приведен перечень всех функций popen и методов дескриптора ph.

Имя Назначение
popen.shell() Выполнение shell-команды
popen.new() Выполнение дочерней программы в новом процессе
popen_handle:read() Считывание данных из дочернего процесса
popen_handle:write() Запись строки в поток stdin дочернего процесса
popen_handle:shutdown() Закрытие канала с std* со стороны родителя
popen_handle:terminate() Отправка сигнала SIGTERM дочернему процессу
popen_handle:kill() Отправка сигнала SIGKILL дочернему процессу
popen_handle:signal() Отправка сигнала дочернему процессу
popen_handle:info() Получение информации о дескрипторе popen
popen_handle:wait() Ожидание, пока дочерний процесс не завершится или не получит сигнал
popen_handle:close() Закрытие дескриптора popen
Константы модуля Константы модуля
Поля дескриптора Поля дескриптора
popen.shell(command[, mode])

Выполнение shell-команды.

Параметры:
  • command (string) – имя выполняемой команды, обязательно
  • mode (string) – режим передачи данных, необязательно
возвращает:

(при успешном выполнении) дескриптор объекта popen, который мы будем называть popen_handle или ph

(при неудачном выполнении) nil, err

Возможные ошибки: если один из параметров задан некорректно, функция возвращает IllegalParams: неправильно задан тип или значение параметра. Другие возможные ошибки смотрите в разделе popen.new().

Возможные значения режима передачи данных mode:

Several mode characters can be set together, for example 'rw', 'rRw'.

Функция shell — это сокращение для popen.new({command}, opts) с opts.shell.setsid и opts.shell.group_signal, установленными в true, и значениями opts.stdin, opts.stdout и opts.stderr, установленными на основе параметра mode.

All std* streams are inherited from the parent by default unless it is changed using mode: 'r' for stdout, 'R' for stderr, or 'w' for stdin.

Пример:

This is the equivalent of the sh -c date command. It starts a process, runs 'date', reads the output, and closes the popen object (ph).

local popen = require('popen')
-- Запуск программы и сохранение ее дескриптора.
local ph = popen.shell('date', 'r')
-- Считывание вывода программы и удаление следующей строки.
local date = ph:read():rstrip()
-- Освобождение ресурсов. Процесс принудительно завершается (но 'date'
-- все равно завершает работу).
ph:close()
print(date)

Unix defines a text file as a sequence of lines. Each line is terminated by a newline (\\n) symbol. The same convention is usually applied for text output of a command. So, when it is redirected to a file, the file will be correct.

Однако внутри приложение обычно работает со строками, которые не завершаются символом новой строки (например, строки сообщений об ошибках). Символ новой строки обычно добавляется прямо перед записью строки в stdout, консоль или лог. Поэтому в примере выше был использован метод rstrip().

popen.new(argv[, opts])

Выполнение дочерней программы в новом процессе.

Параметры:
  • argv (array) – массив, состоящий из запускаемой программы и параметров командной строки, обязательный аргумент; если поле opts.shell установлено в false (по умолчанию), то необходимо задать абсолютный путь к программе
  • opts (table) – таблица параметров, необязательно
возвращает:

(при успешном выполнении) дескриптор объекта popen, который мы будем называть popen_handle или ph

(при неудачном выполнении) nil, err

Возможные ошибки:

  • IllegalParams: некорректный тип или значение параметра
  • IllegalParams: групповой сигнал задан, а setsid — нет

Возможные причины ошибок, когда возвращается nil, err:

  • SystemError: dup(), fcntl(), pipe(), vfork() или close() завершились с ошибкой в родительском процессе
  • SystemError: (временное ограничение) родительский процесс закрыл stdin, stdout или stderr
  • OutOfMemory: невозможно выделить память для дескриптора или временного буфера

Возможные элементы opts:

  • opts.stdin (действие над STDIN_FILENO)
  • opts.stdout (действие над STDOUT_FILENO)
  • opts.stderr (действие над STDERR_FILENO)

Возможные действия файлового дескриптора в таблице opts:

  • popen.opts.INHERIT (== 'inherit') [default] inherit the fd from the parent
  • popen.opts.DEVNULL (== 'devnull') open /dev/null on the fd
  • popen.opts.CLOSE (== 'close') close the fd
  • popen.opts.PIPE (== 'pipe') feed data from fd to parent, or from parent to fd, using a pipe

Таблица opts может содержать таблицу env переменных среды для использования внутри процесса. Каждый элемент opts.env может быть парой ключ-значение (где ключ — имя переменной, а значение — значение переменной).

  • Если opts.env не установлено, то наследуется текущая среда.
  • Если opts.env является пустой таблицей, то среда будет сброшена.
  • Если opts.env является непустой таблицей, то среда будет заменена.

Таблица opts может содержать следующие элементы типа boolean:

Имя Значение по умолчанию Назначение
opts.shell false При значении true выполняется запуск дочернего процесса через sh -c "${opts.argv}". При значении false исполняемый процесс вызывается напрямую.
opts.setsid false При значении true программа запускается в новой сессии. При значении false программа запускается в сессии и группе процессов экземпляра Tarantool.
opts.close_fds true При значении true закрываются все унаследованные родительские файловые дескрипторы. При значении false унаследованные родительские файловые дескрипторы не закрываются.
opts.restore_signals true При значении true сбрасываются все действия сигналов, измененные в родительском процессе. При значении false все действия сигналов, измененные в родительском процессе, наследуются.
opts.group_signal false При значении true отправляется сигнал в группу дочерних процессов, но только при условии, что установлено поле opts.setsid. При значении false сигнал отправляется только одному дочернему процессу.
opts.keep_child false При значении true дочернему процессу (или группе процессов, если поле opts.group_signal установлено в true) не отправляется сигнал SIGKILL. При значении false дочернему процессу (или группе процессов, если поле opts.group_signal установлено в true) отправляется сигнал SIGKILL при выполнении popen_handle:close() или когда Lua GC собирает дескрипторы.

Возвращаемый дескриптор ph дает доступ к методу popen_handle:close() для явного освобождения всех занятых ресурсов, включая сам дочерний процесс, если не установлено поле opts.keep_child. Однако, если метод close() не вызывается для дескриптора в течение его жизни, Lua GC запустит то же самое действие по освобождению ресурсов.

Tarantool рекомендует использовать opts.setsid вместе с opts.group_signal, если дочерний процесс может создать собственные дочерние процессы и их все нужно будет завершить одновременно.

Сигнал не будет отправлен, если дочерний процесс уже был завершен. В противном случае мы можем случайно завершить другой процесс, который имеет тот же идентификатор процесса после освобождения его предыдущим. Это означает, что если дочерний процесс завершается до того, как завершаются его дочерние процессы, то функция не будет отправлять сигнал группе процессов, даже когда установлены opts.setsid и opts.group_signal.

Используйте os.environ(), чтобы передать копию текущей среды с несколькими заменами (см. Пример 2 ниже).

Пример 1

В этом примере выполняется аналог команды sh -c date. Происходит запуск процесса, выполняется 'date', считывается результат и объект popen (ph) закрывается.

local popen = require('popen')

local ph = popen.new({'/bin/date'}, {
    stdout = popen.opts.PIPE,
})
local date = ph:read():rstrip()
ph:close()
print(date) -- например, Thu 16 Apr 2020 01:40:56 AM MSK

Пример 2

Example 2 is quite similar to Example 1, but sets an environment variable and uses the shell builtin 'echo' to show it.

local popen = require('popen')
local env = os.environ()
env['FOO'] = 'bar'
local ph = popen.new({'echo "${FOO}"'}, {
    stdout = popen.opts.PIPE,
    shell = true,
    env = env,
})
local res = ph:read():rstrip()
ph:close()
print(res) -- bar

Пример 3

Пример 3 показывает, как перехватить дочерний поток stderr.

local popen = require('popen')
local ph = popen.new({'echo hello >&2'}, { -- !!
    stderr = popen.opts.PIPE,              -- !!
    shell = true,
})
local res = ph:read({stderr = true}):rstrip()
ph:close()
print(res) -- hello

Пример 4

Пример 4 показывает, как запустить потоковую программу (например, grep, sed и т.д.), записать данные в ее поток stdin и считать данные из stdout.

В этом примере предполагается, что входные данные достаточно малы, чтобы поместиться в буфер канала (обычно его размер равен 64 КиБ, но это зависит от конкретной платформы и ее конфигурации).

Если процесс записывает большое количество данных, он приостановится при выполнении popen_handle:write(). Для разрешения этой проблемы вызывайте popen_handle:read() в цикле в другом файбере (запустите его перед первым вызовом :write()).

Если процесс записывает длинный текст в stderr, он может приостановиться при выполнении write(), потому что буфер канала stderr заполнился. Для решения этой проблемы считывайте из stderr в отдельном файбере.

local function call_jq(input, filter)
    -- Запуск процесса jq, соединение с stdin, stdout и stderr.
    local jq_argv = {'/usr/bin/jq', '-M', '--unbuffered', filter}
    local ph, err = popen.new(jq_argv, {
        stdin = popen.opts.PIPE,
        stdout = popen.opts.PIPE,
        stderr = popen.opts.PIPE,
    })
    if ph == nil then return nil, err end
    -- Запись входных данных в дочерний stdin и отправка EOF.
    local ok, err = ph:write(input)
    if not ok then return nil, err end
    ph:shutdown({stdin = true})
    -- Считывание всех данных до EOF.
    local chunks = {}
    while true do
        local chunk, err = ph:read()
        if chunk == nil then
            ph:close()
            return nil, err
        end
        if chunk == '' then break end -- EOF
        table.insert(chunks, chunk)
    end
    -- Считывание данных диагностики из stderr (при наличии).
    local err = ph:read({stderr = true})
    if err ~= '' then
        ph:close()
        return nil, err
    end
    -- Соединение всех частей вместе, обрезка символа конца строки.
    return table.concat(chunks):rstrip()
end

методы дескриптора popen

object popen_handle
popen_handle:read([opts])

Считывание данных из дочернего процесса.

Параметры:
  • ph (handle) – дескриптор дочернего процесса, созданный через popen.new() или popen.shell()
  • opts (table) – параметры

Возможные элементы opts:

  • opts.stdout (boolean, значение по умолчанию — true, при значении true выполняется считывание из stdout)
  • opts.stderr (boolean, значение по умолчанию — false, при значении true выполняется считывание из stderr)
  • opts.timeout (число, значение по умолчанию — 100 лет, временная квота в секундах)

In other words: by default read() reads from stdout, but reads from stderr if one sets opts.stderr to true. It is not legal to set both opts.stdout and opts.stderr to true.

возвращает:

(при успешном выполнении) строка со считанным значением, пустая строка при EOF

(при неудачном выполнении) nil, err

Possible errors

These errors are raised on incorrect parameters or when the fiber is cancelled:

  • IllegalParams: некорректный тип или значение параметра
  • IllegalParams: вызов дескриптора, который уже был закрыт
  • IllegalParams: одновременно установлены opts.stdout и opts.stderr
  • IllegalParams: запрашиваемая операция ввода-вывода не поддерживается дескриптором (вывод stdout / stderr не перенаправлен)
  • IllegalParams: попытка произвести операцию над закрытым файловым дескриптором
  • FiberIsCancelled: cancelled by external code

nil, err is returned on following failures:

  • SocketError: ошибка ввода-вывода при выполнении read()
  • TimedOut: превышение квоты opts.timeout
  • OutOfMemory: недостаточно памяти для считывания в буфер
  • LuajitError: («not enough memory»): недостаточно памяти для строки Lua
popen_handle:write(str[, opts])

Запись строки str в поток stdin дочернего процесса.

Параметры:
  • ph (handle) – дескриптор дочернего процесса, созданный через popen.new() или popen.shell()
  • str (string) – строка для записи
  • opts (table) – параметры
возвращает:

true on success, false on error
возвращаемое значение:
 

(при успешном выполнении) boolean = true

(при неудачном выполнении) nil, err

Possible opts items are: opts.timeout (number, default 100 years, time quota in seconds).

Возможные ошибки:

  • IllegalParams: некорректный тип или значение параметра
  • IllegalParams: вызов дескриптора, который уже был закрыт
  • IllegalParams: длина строки превышает SSIZE_MAX
  • IllegalParams: запрашиваемая операция ввода-вывода не поддерживается дескриптором (вывод stdin не перенаправлен)
  • IllegalParams: попытка произвести операцию над закрытым файловым дескриптором
  • FiberIsCancelled: файбер отменен во внешней программе

Возможные причины ошибок, когда возвращается nil, err:

  • SocketError: ошибка ввода-вывода при выполнении write()
  • TimedOut: превышение квоты opts.timeout

write() может передать управление (yield) и заблокировать файбер, если дочерний процесс не считывает данные из stdin и буфер канала заполнился. Размер буфера зависит от платформы. Если сомневаетесь, обратите внимание на опцию opts.timeout.

Когда опция opts.timeout не установлена, write() блокирует файбер до момента полной записи данных или возникновения ошибки записи.

popen_handle:shutdown([opts])

Закрытие канала с std* со стороны родителя.

Параметры:
  • ph (handle) – дескриптор дочернего процесса, созданный через popen.new() или popen.shell()
  • opts (table) – параметры
возвращает:

true on success, false on error
возвращаемое значение:
 

(при успешном выполнении) boolean = true

Возможные элементы opts:

  • opts.stdin (boolean) закрыть stdin со стороны родителя
  • opts.stdout (boolean) закрыть stdout со стороны родителя
  • opts.stderr (boolean) закрыть stderr со стороны родителя

Мы можем использовать термин std* для указания на любой из этих элементов.

Возможные ошибки:

  • IllegalParams: некорректный параметр дескриптора
  • IllegalParams: вызов дескриптора, который уже был закрыт
  • IllegalParams: не выбран ни один из потоков stdin, stdout или stderr
  • IllegalParams: запрашиваемая операция ввода-вывода не поддерживается дескриптором (один из потоков std* не перенаправлен)

Основная цель использования shutdown() — отправка EOF в дочерний поток stdin. Однако stdout / stderr может быть уже закрыт со стороны родительского процесса.

shutdown() does not fail on already closed fds (idempotence). However, it fails on an attempt to close the end of a pipe that never existed. In other words, only those std* options that were set to popen.opts.PIPE during handle creation may be used here (for popen.shell(): 'r' corresponds to stdout, 'R' to stderr and 'w' to stdin).

shutdown() не закрывает никакие файловые дескрипторы при завершении с ошибкой: либо закрываются все запрашиваемые дескрипторы (при успешном выполнении), либо ни один из них.

Пример:

local popen = require('popen')
local ph = popen.shell('sed s/foo/bar/', 'rw')
ph:write('lorem foo ipsum')
ph:shutdown({stdin = true})
local res = ph:read()
ph:close()
print(res) -- lorem bar ipsum
popen_handle:terminate()

Отправка сигнала SIGTERM дочернему процессу.

Параметры:
  • ph (handle) – дескриптор дочернего процесса, созданный через popen.new() или popen.shell()
возвращает:

для получения информации об ошибках и возвращаемых значениях смотрите popen_handle:signal()

terminate() просто отправляет сигнал SIGTERM. Он не освобождает никакие ресурсы (такие как память для дескрипторов popen и файловые дескрипторы).

popen_handle:kill()

Отправка сигнала SIGKILL дочернему процессу.

Параметры:
  • ph (handle) – дескриптор дочернего процесса, созданный через popen.new() или popen.shell()
возвращает:

для получения информации об ошибках и возвращаемых значениях смотрите popen_handle:signal()

kill() просто отправляет сигнал SIGKILL. Он не освобождает никакие ресурсы (такие как память для дескрипторов popen и файловые дескрипторы).

popen_handle:signal(signo)

Отправка сигнала дочернему процессу.

Параметры:
  • ph (handle) – дескриптор дочернего процесса, созданный через popen.new() или popen.shell()
  • signo (number) – отправляемый сигнал
возвращает:

(при успешном выполнении) true (сигнал отправлен)

(при неудачном выполнении) nil, err

Возможные ошибки:

  • IllegalParams: некорректный параметр дескриптора
  • IllegalParams: вызов дескриптора, который уже был закрыт

Возможные значения ошибок при возвращении nil, err:

  • SystemError: процесс больше не существует (также может возвращаться для зомби-процессов или когда все процессы в группе являются зомби-процессами (но см. примечание для Mac OS ниже)
  • SystemError: неправильный номер сигнала
  • SystemError: нет разрешения на отправку сигнала процессу или группе процессов (возвращается на Mac OS, когда сигнал отправляется группе процессов, где лидер группы является зомби-процессом (или все процессы являются зомби-процессами, детали неясны) (эта ошибка также может возникнуть по другим причинам, детали неясны)

Если для дескриптора установлены opts.setsid и opts.group_signal, сигнал отправляется группе процессов, а не отдельному процессу. Для подробной информации по групповым сигналам смотрите popen.new(). Внимание: на Mac OS процесс в группе может не получить сигнал, особенно если он только что был разветвлен (возможно это происходит из-за состояния гонки).

Примечание: Некоторые сигналы имеют разные номера на разных платформах. Поэтому в этом модуле мы предлагаем константы popen.signal.SIG*.

popen_handle:info()

Получение информации о дескрипторе popen.

Параметры:
  • ph (handle) – дескриптор дочернего процесса, созданный через popen.new() или popen.shell()
  • signo (number) – отправляемый сигнал
возвращает:

(при успешном выполнении) отформатированный результат
возвращаемое значение:
 

res

Возможные ошибки:

  • IllegalParams: некорректный параметр дескриптора
  • IllegalParams: вызов дескриптора, который уже был закрыт

Результат выводится в следующем формате:

{
    pid = <number> or <nil>,
    command = <string>,
    opts = <table>,
    status = <table>,
    stdin = one-of(
        popen.stream.OPEN   (== 'open'),
        popen.stream.CLOSED (== 'closed'),
        nil,
    ),
    stdout = one-of(
        popen.stream.OPEN   (== 'open'),
        popen.stream.CLOSED (== 'closed'),
        nil,
    ),
    stderr = one-of(
        popen.stream.OPEN   (== 'open'),
        popen.stream.CLOSED (== 'closed'),
        nil,
    ),
}

pid — это идентификатор процесса, когда тот находится в рабочем состоянии; для завершенного процесса pid имеет значение nil.

command — это конкатенация аргументов, разделенных пробелами, которые были переданы в execve(). Аргументы, состоящие из нескольких слов, заключаются в кавычки. Кавычки внутри аргументов не экранируются.

opts – это таблица параметров дескриптора, описанная в разделе opts функции popen.new(). opts.env здесь не отображается, потому что карта переменных среды не хранится в дескрипторе.

status — это таблица, отображающая состояние процесса в следующем формате:

{
    state = one-of(
        popen.state.ALIVE    (== 'alive'),
        popen.state.EXITED   (== 'exited'),
        popen.state.SIGNALED (== 'signaled'),
    )
    -- Отображается при состоянии процесса 'завершенный'.
    exit_code = <number>,
    -- Отображается при состоянии процесса 'принимающий сигнал'.
    signo = <number>,
    signame = <string>,
}

stdin, stdout, and stderr reflect the status of the parent’s end of a piped stream. If a stream is not piped, the field is not present (nil). If it is piped, the status may be either popen.stream.OPEN (== 'open') or popen.stream.CLOSED (== 'closed'). The status may be changed from 'open' to 'closed' by a popen_handle:shutdown({std… = true}) call.

Пример 1

(в консоли Tarantool)

tarantool> require('popen').new({'/usr/bin/touch', '/tmp/foo'})
---
- command: /usr/bin/touch /tmp/foo
  status:
    state: alive
  opts:
    stdout: inherit
    stdin: inherit
    group_signal: false
    keep_child: false
    close_fds: true
    restore_signals: true
    shell: false
    setsid: false
    stderr: inherit
  pid: 9499
...

Пример 2

(в консоли Tarantool)

tarantool> require('popen').shell('grep foo', 'wrR')
---
- stdout: open
  command: sh -c 'grep foo'
  stderr: open
  status:
    state: alive
  stdin: open
  opts:
    stdout: pipe
    stdin: pipe
    group_signal: true
    keep_child: false
    close_fds: true
    restore_signals: true
    shell: true
    setsid: true
    stderr: pipe
  pid: 10497
...
popen_handle:wait()

Ожидание, пока дочерний процесс не завершится или не получит сигнал.

Параметры:
  • ph (handle) – дескриптор дочернего процесса, созданный через popen.new() или popen.shell()
  • signo (number) – отправляемый сигнал
возвращает:

(при успешном выполнении) отформатированный результат
возвращаемое значение:
 

res

Возможные ошибки:

  • IllegalParams: некорректный параметр дескриптора
  • IllegalParams: вызов дескриптора, который уже был закрыт
  • FiberIsCancelled: файбер отменен во внешней программе

Отформатированный результат представляет собой таблицу состояний процесса (аналогично компоненту status таблицы, возвращаемой через popen_handle:info()).

popen_handle:close()

Закрытие дескриптора popen.

Параметры:
  • ph (handle) – дескриптор дочернего процесса, созданный через popen.new() или popen.shell()
возвращает:

(при успешном выполнении) true

(при неудачном выполнении) nil, err

Возможные ошибки:

  • IllegalParams: некорректный параметр дескриптора

Возможные результаты диагностики, когда возвращается nil, err (не рассматривайте эти случаи как ошибки):

  • SystemError: нет разрешения на отправку сигнала процессу или группе процессов (это сообщение диагностики может появиться из-за особенностей обработки зомби-процессов в Mac OS, когда установлен opts.group_signal, см. popen_handle:signal(). Оно также может появиться по другим причинам, детали неясны).

Если известно, что процесс был завершен, то в результате всегда возвращается true (например, после выполнения popen_handle:wait() не будет отправлено никакого сигнала, так что никакой ошибки не может возникнуть).

close() принудительно завершает процесс через SIGKILL и освобождает все ресурсы, связанные с дескриптором popen.

Подробная информация об отправке сигналов:

  • Сигнал отправляется только когда поле opts.keep_child не установлено.
  • Сигнал отправляется только когда процесс находится в рабочем состоянии согласно информации, доступной на текущей итерации цикла событий. (Здесь есть слабое место: сигнал может быть отправлен зомби-процессу, но это не представляет никакой угрозы).
  • Сигнал отправляется процессу или группе процессов в зависимости от opts.group_signal. (Для подробной информации о групповых сигналах смотрите popen.new()).

Ресурсы освобождаются вне зависимости от того, успешно ли отправился сигнал: дескрипторы файлов закрываются, память освобождается, а дескриптор popen помечается как закрытый.

Над закрытым дескриптором невозможно выполнять никакие операции кроме close(), которая всегда выполняется успешно над закрытым дескриптором (идемпотентность).

close() может вернуть true или nil, err, но она всегда освобождает ресурсы дескриптора. Поэтому для того, кто отправил сигнал, любое возвращаемое значение означает успешное выполнение. Возвращаемые значения только дают информацию для логирования или составления отчетов.

Поля дескриптора

popen_handle.pid
popen_handle.command
popen_handle.opts
popen_handle.status
popen_handle.stdin
popen_handle.stdout
popen_handle.stderr

За более подробной информацией обратитесь к popen_handle:info().

Константы модуля

- popen.opts
  - INHERIT (== 'inherit')
  - DEVNULL (== 'devnull')
  - CLOSE   (== 'close')
  - PIPE    (== 'pipe')

- popen.signal
  - SIGTERM (== 9)
  - SIGKILL (== 15)
  - ...

- popen.state
  - ALIVE    (== 'alive')
  - EXITED   (== 'exited')
  - SIGNALED (== 'signaled')

- popen.stream
  - OPEN    (== 'open')
  - CLOSED  (== 'closed')

Модуль socket

Общие сведения

Модуль socket позволяет обмениваться данными с локальным или удаленным хостом по BSD-сокетам в режиме с установлением соединений (TCP) или на основе датаграмм (UDP). Семантика вызовов в API модуля socket точно соответствует семантике соответствующих вызовов в POSIX.

Функции для настройки и подключения: socket, sysconnect, tcp_connect. Функции для отправки данных: send, sendto, write, syswrite. Функции для получения данных: recv, recvfrom, read. Функции для ожидания отправки/получения данных: wait, readable, writable. Функции для установки флагов: nonblock, setsockopt. Функции для остановки и отключения: shutdown, close. Функции для проверки ошибок: errno, error.

Указатель

Ниже приведен перечень всех функций модуля socket.

Имя Назначение
socket() Создание сокета
socket.tcp_connect() Подключение к удаленному хосту с помощью сокета
socket.getaddrinfo() Получение информации об удаленном узле
socket.tcp_server() Использование Tarantool в качестве TCP-сервера
socket.bind() Привязка сокета к данному хосту/порту
socket_object:sysconnect() Подключение к удаленному хосту с помощью сокета
socket_object:send()
socket_object:write()		 Отправка данных по подключенному сокету
socket_object:syswrite() Запись данных в буфер сокета без блокировки
socket_object:recv() Чтение с подключенного сокета
socket_object:sysread() Чтение данных из буфера сокета без блокировки
socket_object:bind() Привязка сокета к данному хосту/порту
socket_object:listen() Начало прослушивания входящих соединений
socket_object:accept() Принятие запроса клиента на соединение + создание подключенного сокета
socket_object:sendto() Отправка сообщения по UDP-сокету на указанный хост
socket_object:recvfrom() Получение сообщения по UDP-сокету
socket_object:shutdown() Отключение передачи данных на чтение, на запись или в обоих направлениях
socket_object:close() Закрытие сокета
socket_object:error()
socket_object:errno()		 Получение информации о последней ошибке на сокете
socket_object:setsockopt() Определение флагов сокета
socket_object:getsockopt() Получение флагов сокета
socket_object:linger() Установить/убрать флаг SO_LINGER
socket_object:nonblock() Определить/получить значение флага
socket_object:readable() Ожидание доступности чего-либо для чтения
socket_object:writable() Ожидание доступности чего-либо для записи
socket_object:wait() Ожидание доступности чего-либо для чтения или записи
socket_object:name() Получение информации о ближней стороне соединения
socket_object:peer() Получение информации о дальней стороне соединения
socket.iowait() Ожидание активности чтения/записи
LuaSocket wrapper functions Несколько методов эмуляции LuaSocket API

Typically a socket session will begin with the setup functions, will set one or more flags, will have a loop with sending and receiving functions, will end with the teardown functions – as an example at the end of this section will show. Throughout, there may be error-checking and waiting functions for synchronization. To prevent a fiber containing socket functions from «blocking» other fibers, the implicit yield rules will cause a yield so that other processes may take over, as is the norm for cooperative multitasking.

Для всех примеров в данном разделе имя сокета будет sock, а вызов функции будет выглядеть как sock:имя_функции(...).

socket.__call(domain, type, protocol)

Создание нового TCP-сокета или UDP-сокета. Значения аргумента остаются теми же, что и на странице socket(2) руководства по Linux.

возвращает:неподключенный сокет или nil.
тип возвращаемого значения:
 пользовательские данные

Пример:

socket('AF_INET', 'SOCK_STREAM', 'tcp')
socket.tcp_connect(host[, port[, timeout]])

Подключение к удаленному хосту с помощью сокета.

Параметры:
  • host (string) – URL или IP-адрес
  • port (number) – номер порта
  • timeout (number) – количество секунд ожидания
возвращает:

(if error) {nil, error-message-string}. (if no error) a new socket object.
тип возвращаемого значения:
 

socket object, which may be viewed as a table

Пример:

sock, e = socket.tcp_connect('127.0.0.1', 3301)
if sock == nil then print(e) end
socket.getaddrinfo(host, port[, timeout[, {option-list}]])
socket.getaddrinfo(host, port[, {option-list}])

Функция socket.getaddrinfo() используется для поиска информации об удаленном узле, чтобы можно было передать правильные аргументы для sock:sysconnect(). Эта функция может использовать конфигурационный параметр worker_pool_threads.

Параметры:
  • host (string) – URL или IP-адрес
  • port (number/string) – номер порта — число или строка
  • timeout (number) – количество секунд ожидания
  • options (table) –
    • type – предпочтительный тип сокета
    • family – предпочтительное семейство адресов
    • protocol
    • flags – дополнительные опции (подробнее о них здесь)
возвращает:

(if error) {nil, error-message-string}. (if no error) A table containing these fields: «host», «family», «type», «protocol», «port».
тип возвращаемого значения:
 

таблица

Пример:

tarantool> socket.getaddrinfo('tarantool.org', 'http')
---
- - host: 188.93.56.70
    family: AF_INET
    type: SOCK_STREAM
    protocol: tcp
    port: 80
  - host: 188.93.56.70
    family: AF_INET
    type: SOCK_DGRAM
    protocol: udp
    port: 80
...
-- To find the available values for the options use the following:
tarantool> socket.internal.AI_FLAGS -- or SO_TYPE, or DOMAIN
---
- AI_ALL: 256
  AI_PASSIVE: 1
  AI_NUMERICSERV: 4096
  AI_NUMERICHOST: 4
  AI_V4MAPPED: 2048
  AI_ADDRCONFIG: 1024
  AI_CANONNAME: 2
...
socket.tcp_server(host, port, handler-function-or-table[, timeout])

Функция socket.tcp_server() заставляет Tarantool выступать в качестве сервера для принятия подключений. Обычно для этой же цели используется box.cfg{listen=…}.

Параметры:
  • host (string) – имя или IP хоста
  • port (number) – порт хоста, может быть 0
  • handler-function-or-table (function/table) – что выполнить после подключения
  • timeout (number) – время ожидания в секундах при разрешении имени хоста в IP-адрес
возвращает:

(if error) {nil, error-message-string}. (if no error) a new socket object.
тип возвращаемого значения:
 

socket object, which may be viewed as a table

Параметр handler-function-or-table может представлять собой просто имя функции или объявление функции: handler_function. Или же может быть таблицей: {handler = handler_function [, prepare = prepare_function] [, name = name] }. Функция handler_function является обязательной, в ней может быть только один параметр = сокет (используется для непрерывной работы после установки соединения), выполняется один раз за соединение после того, как произойдет accept(). Функция prepare_function необязательна; она выполняется однократно перед установкой соединения (bind()) на слушающем сокете и должна возвращать либо значение бэклога, либо ничего. Например:

socket.tcp_server('localhost', 3302, function (s) loop_loop() end)
socket.tcp_server('localhost', 3302, {handler=hfunc, name='name'})
socket.tcp_server('localhost', 3302, {handler=hfunc, prepare=pfunc})

Более полный пример см. в разделе Использование tcp_server для получения содержимого файла, отправленного по socat и Использование tcp_server с handler и prepare.

socket.bind(host, port)

Bind a socket to the given host/port. This is equivalent to socket_object:bind(), but is done on the result of require('socket'), rather than on the socket object.

Параметры:
  • host (string) – URL или IP-адрес
  • port (number) – номер порта
возвращает:

(if error) {nil, error-message-string}. (if no error) A table which may have information about the bind result.
тип возвращаемого значения:
 

таблица
object socket_object
socket_object:sysconnect(host, port)

Подключение к удаленному хосту с помощью существующего сокета. Значения аргументов будут такие же, как в tcp_connect(). Хост должен представлять собой IP-адрес.

Параметры:
  • Либо:
    • host – строковое представление IPv4 адреса или IPv6 адреса;
    • port – число.
  • Либо:
    • host – строка, которая содержит «unix/»;
    • port – строка, которая содержит путь к Unix-сокету.
  • Либо:
    • host – число, 0 (ноль), что означает «все локальные интерфейсы»;
    • port – число. Если номер порта – 0 (ноль), сокет будет привязан к случайному локальному порту.
возвращает:значение объекта сокета может изменяться, если будет выполнена функция sysconnect().
тип возвращаемого значения:
 boolean (логический)

Пример:

socket = require('socket')
sock = socket('AF_INET', 'SOCK_STREAM', 'tcp')
sock:sysconnect(0, 3301)
socket_object:send(data)
socket_object:write(data)

Отправка данных по подключенному сокету.

Параметры:
  • data (string) – что отправляется
возвращает:

количество отправляемых байтов.
тип возвращаемого значения:
 

число

Возможные ошибки: nil в случае ошибки.

socket_object:syswrite(size)

Запись максимально возможного количества данных в буфер сокета без блокировки. Используется редко. Для получения подробной информации см. описание.

socket_object:recv(size)

Чтение количества байтов, определенного в size, из подключенного сокета. Внутренний буфер опережающего считывания используется для уменьшения использования ресурсов на вызов.

Параметры:
возвращает:

строка запрошенной длины, если выполнено.
тип возвращаемого значения:
 

строка

Возможные ошибки: В случае ошибки возвращается пустая строка, после чего статус, errno, errstr. Если передача данных на запись закрыта с другой стороны, возвращаются оставшиеся для чтения данные из сокета (возможно, пустая строка), после чего идет статус «eof» (конец файла).

socket_object:read(limit[, timeout])
socket_object:read(delimiter[, timeout])
socket_object:read({options}[, timeout])

Чтение данных из подключенного сокета до выполнения какого-либо условия и возврат прочтенных байтов. Производится чтения количества байтов, которое указано в параметре limit, либо до символа-разделителя, либо до истечения времени ожидания. В отличие от socket_object:recv (где используется внутренний буфер опережающего считывания), socket_object:read зависит от буфера сокета.

Параметры:
  • limit (integer) – максимальное количество байтов для чтения, например, 50 означает «остановиться на 50 байтах»
  • delimiter (string) – separator for example ? means «stop after a question mark»; this parameter can accept a table of separators, for example, delimiter = {"\n", "\r"}
  • timeout (number) – максимальное количество секунд ожидания, например, 50 означает «остановиться через 50 секунд».
  • options (table) – chunk=предел и/или delimiter=разделитель, например, {chunk=5,delimiter='x'}.
возвращает:

пустая строка, если нет данных для чтения, либо нулевое значение nil в случае ошибки, либо строка, ограниченная количеством байтов в limit, которая может включать в себя байты, совпадающие с выражением delimiter.
тип возвращаемого значения:
 

строка
socket_object:sysread(size)

Возврат данных из буфера сокета без блокировки.Если сокет с блокировкой, sysread() может блокировать процесс вызова. Используется редко. Для получения подробной информации, см. описание.

Параметры:
  • size (integer) – максимальное количество байтов для чтения, например, 50 означает «остановиться на 50 байтах»
возвращает:

пустая строка, если нет данных для чтения, либо нулевое значение nil в случае ошибки, либо строка, ограниченная количеством байтов в size.
тип возвращаемого значения:
 

строка
socket_object:bind(host[, port])

Привязка сокета к данному хосту/порту. UDP-сокет после привязки может использоваться для получения данных (см. socket_object.recvfrom). TCP-сокет может использоваться для принятия новых соединений после перевода в режим прослушивания.

Параметры:
  • host (string) – URL или IP-адрес
  • port (number) – номер порта
возвращает:

true (правда), если выполнено, false (ложь) в случае ошибки. Если возвращается false, используйте socket_object:errno() или socket_object:error() для получения подробной информации.
тип возвращаемого значения:
 

boolean (логический)
socket_object:listen(backlog)

Начало прослушивания входящих соединений.

Параметры:
  • backlog – в Linux очередь запросов backlog может быть в /proc/sys/net/core/somaxconn, в BSD очередь запросов может представлять собой SOMAXCONN.
возвращает:

true (правда), если выполнено, false (ложь) в случае ошибки.
тип возвращаемого значения:
 

boolean (логический).
socket_object:accept()

Принятие нового клиентского соединения и создание нового подключенного сокета. Установка блокирующего режима на сокете явным образом после принятия соединения приведет к эффективной работе.

возвращает:новый сокет, если выполнено.
тип возвращаемого значения:
 пользовательские данные

Возможные ошибки: nil.

socket_object:sendto(host, port, data)

Отправка сообщения по UDP-сокету на указанный хост.

Параметры:
  • host (string) – URL или IP-адрес
  • port (number) – номер порта
  • data (string) – что отправляется
возвращает:

количество отправляемых байтов.
тип возвращаемого значения:
 

число

Возможные ошибки: в случае ошибки возвращает nil, а также может вернуть статус, errno, errstr.

socket_object:recvfrom(size)

Получение сообщения по UDP-сокету.

Параметры:
возвращает:

сообщение, таблица с полями «host», «family» и «port».
тип возвращаемого значения:
 

строка, таблица

Возможные ошибки: в случае ошибки возвращает nil, статус, errno, errstr.

Пример:

После message_content, message_sender = recvfrom(1) значением message_content может быть строка, которая содержит „X“, а значением message_sender может быть таблица, которая содержит

message_sender.host = '18.44.0.1'
message_sender.family = 'AF_INET'
message_sender.port = 43065
socket_object:shutdown(how)

Отключение передачи данных на чтение, на запись или в обоих направлениях.

Параметры:
  • how – socket.SHUT_RD, socket.SHUT_WR, or socket.SHUT_RDWR.
возвращает:

true (правда) или false (ложь).
тип возвращаемого значения:
 

boolean (логический)
socket_object:close()

Закрытие (удаление) сокета. Закрытый сокет больше не должен использоваться. Сокет будет закрыт автоматически, когда сборщик мусора Lua удалит данные.

возвращает:true (правда), если выполнено, false (ложь) в случае ошибки. Например, если сокет sock уже закрыт, sock:close() вернет false.
тип возвращаемого значения:
 boolean (логический)
socket_object:error()
socket_object:errno()

Получение информации о последней ошибке на сокете, если таковая была. Ошибки не выдают исключения, поэтому данные функции необходимы.

возвращает:результат sock:errno(), результат sock:error(). Если ошибки нет, то sock:errno() вернет 0 и sock:error().
тип возвращаемого значения:
 число, строка
socket_object:setsockopt(level, name, value)

Определение флагов сокета. Значения аргумента будут такими же, что и на странице getsockopt(2) руководства по Linux. Tarantool принимает следующие:

  • SO_ACCEPTCONN
  • SO_BINDTODEVICE
  • SO_BROADCAST
  • SO_DEBUG
  • SO_DOMAIN
  • SO_ERROR
  • SO_DONTROUTE
  • SO_KEEPALIVE
  • SO_MARK
  • SO_OOBINLINE
  • SO_PASSCRED
  • SO_PEERCRED
  • SO_PRIORITY
  • SO_PROTOCOL
  • SO_RCVBUF
  • SO_RCVBUFFORCE
  • SO_RCVLOWAT
  • SO_SNDLOWAT
  • SO_RCVTIMEO
  • SO_SNDTIMEO
  • SO_REUSEADDR
  • SO_SNDBUF
  • SO_SNDBUFFORCE
  • SO_TIMESTAMP
  • SO_TYPE

Установка флага SO_LINGER осуществляется с помощью sock:linger(active).

socket_object:getsockopt(level, name)

Получение флагов сокета. Список возможных флагов см. с помощью sock:setsockopt().

socket_object:linger([active])

Установить или убрать флаг SO_LINGER. Описание флага см. в руководстве по Linux.

Параметры:
  • active (boolean) –
возвращает:

новые значения active и timeout.
socket_object:nonblock([flag])
  • sock:nonblock() возвращает текущее значение флага.
  • sock:nonblock(false) устанавливает флаг на false и возвращает false.
  • sock:nonblock(true) устанавливает флаг на true и возвращает true.

Эту функцию можно использовать до вызова функции, которая в противном случае будет блокировать бесконечно.

socket_object:readable([timeout])

Ожидание доступности чего-либо для чтения или до истечения времени ожидания.

возвращает:true, если сокет доступен для чтения, false, если истекло время ожидания;
socket_object:writable([timeout])

Ожидание доступности чего-либо для записи или до истечения времени ожидания.

возвращает:true, если сокет доступен для записи, false, если истекло время ожидания;
socket_object:wait([timeout])

Ожидание доступности чего-либо для чтения или записи, или до истечения времени ожидания.

возвращает:„R“, если сокет доступен для чтения, „W“, если сокет доступен для записи, „RW“, если сокет доступен и для чтения, и для записи, „“ (пустая строка), если истекло время ожидания;
socket_object:name()

Функция sock:name() используется для получения информации о ближней стороне соединения. Если сокет привязан к xyz.com:45, то sock:name вернет информацию о [host:xyz.com, port:45]. Аналогичная функция в POSIX – getsockname().

возвращает:Таблица со следующими полями: «host», «family», «type», «protocol», «port».
тип возвращаемого значения:
 таблица
socket_object:peer()

Функция sock:peer() используется для получения информации о дальней стороне соединения. Если TCP-соединение установлено с удаленным хостом tarantool.org:80, то sock:peer() вернет информацию о [host:tarantool.org, port:80]. Аналогичная функция в POSIX – getpeername().

возвращает:Таблица со следующими полями: «host», «family», «type», «protocol», «port».
тип возвращаемого значения:
 таблица
socket.iowait(fd, read-or-write-flags[, timeout])

Функция socket.iowait() используется для ожидания, пока дескриптор файла не будет активен для чтения или записи.

Параметры:
  • fd – дескриптор файла
  • read-or-write-flags – „R“ или 1 = чтение, „W“ или 2 = запись, „RW“ или 3 = чтение|запись.
  • timeout – количество секунд ожидания

Если значение параметра fd – nil, то будет режим ожидания до истечения времени, указанного в параметре timeout. Если timeout – nil или не указан, время ожидания считается бесконечным.

Как правило, возвращается значение совершенного действия („R“ или „W“, или „RW“, или 1, или 2, или 3). Если время ожидания в timeout проходит без действий чтения или записи, возвращается ошибка = ETIMEDOUT.

Пример: socket.iowait(sock:fd(), 'r', 1.11)

Функции обертки LuaSocket

The LuaSocket API has functions that are equivalent to the ones described above, with different names and parameters, for example connect() rather than tcp_connect(). Tarantool supports these functions so that third-party packages which depend on them will work.

Проект LuaSocket находится на github. Описание API находится в руководстве по LuaSocket (нажмите на ссылки «введение» и «ссылка» внизу главной страницы руководства).

Пример для Tarantool - Использование сокета с функциями обертки LuaSocket.

Примеры

Использование TCP-сокета в интернете

В данном примере устанавливается соединение по интернету между экземпляром Tarantool и tarantool.org, затем отправляется HTTP-сообщение заголовка «head» и возвращается ответ: «HTTP/1.1 200 OK» или что-то другое, если сайт перемещен. Так не слишком удобно взаимодействовать с определенным сайтом, но пример показывает работу системы.

tarantool> socket = require('socket')
---
...
tarantool> sock = socket.tcp_connect('tarantool.org', 80)
---
...
tarantool> type(sock)
---
- table
...
tarantool> sock:error()
---
- null
...
tarantool> sock:send("HEAD / HTTP/1.0\r\nHost: tarantool.org\r\n\r\n")
---
- 40
...
tarantool> sock:read(17)
---
- HTTP/1.1 302 Move
...
tarantool> sock:close()
---
- true
...

Использование сокета с функциями обертки LuaSocket

Это вариант более раннего примера «Использование TCP-подключения через Интернет». В нем используются функции обертки LuaSocket, с слишком коротким временем ожидания, так что, скорее всего, произойдет ошибка «Connection timed out» (Таймаут соединения). Более распространенным способом определения таймаута является использование функции tcp_connect().

tarantool> socket = require('socket')
---
...
tarantool> sock = socket.connect('tarantool.org', 80)
---
...
tarantool> sock:settimeout(0.001)
---
- 1
...
tarantool> sock:send("HEAD / HTTP/1.0\r\nHost: tarantool.org\r\n\r\n")
---
- 40
...
tarantool> sock:receive(17)
---
- null
- Connection timed out
...
tarantool> sock:close()
---
- 1
...

Использование UDP-сокета на localhost

Ниже приведен пример с датаграммами. Устанавливается два соединения с 127.0.0.1 (localhost): sock_1 и sock_2. С помощью sock_2 отправляется сообщение на sock_1. С помощью sock_1 получается сообщение. Отображается полученное сообщение. Оба соединения закрываются.
Компьютеру так не слишком удобно взаимодействовать с самим собой, но пример показывает работу системы.

tarantool> socket = require('socket')
---
...
tarantool> sock_1 = socket('AF_INET', 'SOCK_DGRAM', 'udp')
---
...
tarantool> sock_1:bind('127.0.0.1')
---
- true
...
tarantool> sock_2 = socket('AF_INET', 'SOCK_DGRAM', 'udp')
---
...
tarantool> sock_2:sendto('127.0.0.1', sock_1:name().port,'X')
---
- 1
...
tarantool> message = sock_1:recvfrom(512)
---
...
tarantool> message
---
- X
...
tarantool> sock_1:close()
---
- true
...
tarantool> sock_2:close()
---
- true
...

Использование tcp_server для получения содержимого файла, отправленного по socat

Ниже приведен пример функции tcp_server, которая читает строки с клиента и выводит результат. На клиентской стороне утилита socat в Linux будет использоваться для отправки целого файла на чтение функции tcp_server.

Запустите две оболочки. Первая оболочка будет экземпляром сервера. Вторая оболочка будет клиентом.

В первой оболочке запустите Tarantool и выполните:

box.cfg{}
socket = require('socket')
socket.tcp_server('0.0.0.0', 3302,
{
  handler = function(s)
    while true do
      local request
      request = s:read("\n");
      if request == "" or request == nil then
        break
      end
      print(request)
    end
  end,
  prepare = function()
    print('Initialized')
  end
}
)

Вышеуказанный код означает:

  1. Использовать tcp_server() для ожидания подключения с любого хоста по порту 3302.
  2. Когда это произойдет, ввести цикл, который читает по сокету и выводит результат чтения. Разделителем для функции чтения будет «\n», поэтому каждое выполнение read() выполнит чтение строки до перевода строки, включая перевод строки.

Во второй оболочке создайте файл, который содержит несколько строк. Содержимое не имеет значения. Предположим, что первая строка содержит A, вторая строка содержит B, третья строка содержит C. Назовите этот файл «tmp.txt».

Во второй оболочке используйте утилиту socat для отправки файла tmp.txt на экземпляр сервера по хосту и порту:

$ socat TCP:localhost:3302 ./tmp.txt

Теперь смотрите, что происходит в первой оболочке. Выводятся строки «A», «B», «C».

Использование tcp_server с handler и prepare

Ниже приведен пример функции tcp_server с использованием handler и prepare.

Запустите две оболочки. Первая оболочка будет экземпляром сервера. Вторая оболочка будет клиентом.

В первой оболочке запустите Tarantool и выполните:

box.cfg{}
socket = require('socket')
sock = socket.tcp_server(
  '0.0.0.0',
  3302,
  {prepare =
     function(sock)
       print('listening on socket ' .. sock:fd())
       sock:setsockopt('SOL_SOCKET','SO_REUSEADDR',true)
       return 5
     end,
   handler =
    function(sock, from)
      print('accepted connection from: ')
      print('  host: ' .. from.host)
      print('  family: ' .. from.family)
      print('  port: ' .. from.port)
    end
  }
)

Вышеуказанный код означает:

  1. Использовать tcp_server() для ожидания подключения с любого хоста по порту 3302.
  2. Указать, что будет первый вызов prepare, который покажет что-то о сервере, затем вызовет setsockopt(...'SO_REUSEADDR'...) (это та же самая опция, которую Тарантул бы установил, если бы не было prepare), а затем вернет 5 (это довольно низкий размер очереди бэклога).
  3. Указать, что будут вызовы handler по каждому соединению, которые будут отображать что-то о клиенте.

Теперь смотрите, что происходит в первой оболочке. Выведется что-то вроде „listening on socket 12“.

Во второй оболочке запустите Tarantool и выполните:

box.cfg{}
require('socket').tcp_connect('127.0.0.1', 3302)

Теперь смотрите, что происходит на первой оболочке. На дисплее появится что-то вроде „accepted connection from host: 127.0.0.1 family: AF_INET port: 37186“.

Модуль strict

Модуль strict включает в себя функции для включения или отключения строгого режима «strict mode». Когда включен строгий режим, попытка использовать необъявленную глобальную переменную приведет к ошибке. Глобальная переменная считается необъявленной, если ей никогда не было присвоено значение. Часто это указывает на ошибку программирования.

По умолчанию, строгий режим отключен, не считая случаев, когда сборка Tarantool производилась с помощью -DCMAKE_BUILD_TYPE=Debug – см. варианты сборки в разделе сборка из исходников.

Пример:

tarantool> strict = require('strict')
---
...
tarantool> strict.on()
---
...
tarantool> a = b -- строгий режим включен, поэтому появляется ошибка
---
- error: ... variable ''b'' is not declared'
...
tarantool> strict.off()
---
...
tarantool> a = b -- строгий режим отключен, поэтому ошибки нет
---
...

Модуль string

Общие сведения

Модуль string включает в себя всё из стандартной библиотеки для работы со строками в Lua, а также некоторые расширения специально для Tarantool.

В данном разделе мы рассматриваем только дополнительные функции, добавленные разработчиками Tarantool.

Указатель

Ниже приведен перечень всех функций библиотеки string.

Имя Назначение
string.ljust() Выравнивание строки по левому полю
string.rjust() Выравнивание строки по правому полю
string.hex() Given a string, return hexadecimal values
string.fromhex() Given hexadecimal values, return a string
string.startswith() Проверка, начинается ли строка с заданной подстроки
string.endswith() Проверка, заканчивается ли строка на заданную подстроку
string.lstrip() Remove characters from the left of a string
string.rstrip() Remove characters from the right of a string
string.split() Разделение строки на таблицу со строками
string.strip() Удаление пробелов слева и справа от строки
string.ljust(input-string, width[, pad-character])

Возврат строки, выровненной по левому краю, шириной, указанной в width.

Параметры:
  • input-string (string) – строка для выравнивания по левому краю
  • width (integer) – ширина строки после выравнивания по левому краю
  • pad-character (string) – отдельный символ, по умолчанию = 1 пробел
Возвращается:

выровненная по левому краю строка (не изменяется, если ширина <= длине строки)
Тип возвращаемого значения:
 

строка

Пример:

tarantool> string = require('string')
---
...
tarantool> string.ljust(' A', 5)
---
- ' A   '
...
string.rjust(input-string, width[, pad-character])

Возврат строки, выровненной по правому краю, шириной, указанной в width.

Параметры:
  • input-string (string) – строка для выравнивания по правому краю
  • width (integer) – ширина строки после выравнивания по правому краю
  • pad-character (string) – отдельный символ, по умолчанию = 1 пробел
Возвращается:

выровненная по правому краю строка (не изменяется, если ширина <= длине строки)
Тип возвращаемого значения:
 

строка

Пример:

tarantool> string = require('string')
---
...
tarantool> string.rjust('', 5, 'X')
---
- 'XXXXX'
...
string.hex(input-string)

Возврат шестнадцатеричного значения введенной строки.

Параметры:
  • input-string (string) – обрабатываемая строка
Возвращается:

шестнадцатеричное число, два символа шестнадцатеричных цифр для каждого введенного символа
Тип возвращаемого значения:
 

строка

Пример:

tarantool> string = require('string')
---
...
tarantool> string.hex('ABC ')
---
- '41424320'
...
string.fromhex(hexadecimal-input-string)

Given a string containing pairs of hexadecimal digits, return a string with one byte for each pair. This is the reverse of string.hex(). The hexadecimal-input-string must contain an even number of hexadecimal digits.

Параметры:
  • hexadecimal-input-string (string) – string with pairs of hexadecimal digits
Возвращается:

string with one byte for each pair of hexadecimal digits
Тип возвращаемого значения:
 

строка

Пример:

tarantool> string = require('string')
---
...
tarantool> string.fromhex('41424320')
---
- 'ABC '
...
string.startswith(input-string, start-string[, start-pos[, end-pos]])

Возврат true (правда), если input-string начинается со start-string, в противном случае, возврат false (ложь).

Параметры:
  • input-string (string) – строка, где производится поиск данных из start-string
  • start-string (string) – искомая строка
  • start-pos (integer) – положение: где начинать искать в пределах input-string
  • end-pos (integer) – положение: где заканчивать искать в пределах input-string
Возвращается:

true (правда) или false (ложь)
Тип возвращаемого значения:
 

boolean (логический)

Значения start-pos и end-pos могут быть отрицательными, что означает, что положение вычисляется с конца строки.

Пример:

tarantool> string = require('string')
---
...
tarantool> string.startswith(' A', 'A', 2, 5)
---
- true
...
string.endswith(input-string, end-string[, start-pos[, end-pos]])

Возврат true (правда), если input-string заканчивается на end-string, в противном случае, возврат false (ложь).

Параметры:
  • input-string (string) – строка, где производится поиск данных из end-string
  • end-string (string) – искомая строка
  • start-pos (integer) – положение: где начинать искать в пределах input-string
  • end-pos (integer) – положение: где заканчивать искать в пределах input-string
Возвращается:

true (правда) или false (ложь)
Тип возвращаемого значения:
 

boolean (логический)

Значения start-pos и end-pos могут быть отрицательными, что означает, что положение вычисляется с конца строки.

Пример:

tarantool> string = require('string')
---
...
tarantool> string.endswith('Baa', 'aa')
---
- true
...
string.lstrip(input-string[, list-of-characters])

Return the value of the input string, after removing characters on the left. The optional list-of-characters parameter is a set not a sequence, so string.lstrip(...,'ABC') does not mean strip 'ABC', it means strip 'A' or 'B' or 'C'.

Параметры:
  • input-string (string) – обрабатываемая строка
  • list-of-characters (string) – what characters can be stripped. Default = space.
Возвращается:

result after stripping characters from input string
Тип возвращаемого значения:
 

строка

Пример:

tarantool> string = require('string')
---
...
tarantool> string.lstrip(' ABC ')
---
- 'ABC '
...
string.rstrip(input-string[, list-of-characters])

Return the value of the input string, after removing characters on the right. The optional list-of-characters parameter is a set not a sequence, so string.rstrip(...,'ABC') does not mean strip 'ABC', it means strip 'A' or 'B' or 'C'.

Параметры:
  • input-string (string) – обрабатываемая строка
  • list-of-characters (string) – what characters can be stripped. Default = space.
Возвращается:

result after stripping characters from input string
Тип возвращаемого значения:
 

строка

Пример:

tarantool> string = require('string')
---
...
tarantool> string.rstrip(' ABC ')
---
- ' ABC'
...
string.split(input-string[, split-string[, max]])

Разделение input-string на одну или более выводимых строк в таблице. Места разделения указаны в split-string.

Параметры:
  • input-string (string) – строка для разделения
  • split-string (string) – искомая строка в пределах input-string. По умолчанию = пробел.
  • max (integer) – максимальное количество символов-разделителей от начала обрабатываемой строки. Результат содержит не более max + 1 частей.
Возвращается:

таблица строк, которые были разделены из input-string
Тип возвращаемого значения:
 

таблица

Пример:

tarantool> string = require('string')
---
...
tarantool> string.split("A:B:C:D:F", ":", 2)
---
- - A
  - B
  - C:D:F
...
string.strip(input-string[, list-of-characters])

Return the value of the input string, after removing characters on the left and the right. The optional list-of-characters parameter is a set not a sequence, so string.strip(...,'ABC') does not mean strip 'ABC', it means strip 'A' or 'B' or 'C'.

Параметры:
  • input-string (string) – обрабатываемая строка
  • list-of-characters (string) – what characters can be stripped. Default = space.
Возвращается:

result after stripping characters from input string
Тип возвращаемого значения:
 

строка

Пример:

tarantool> string = require('string')
---
...
tarantool> string.strip(' ABC ')
---
- ABC
...

Модуль swim

Общие сведения

The swim module contains Tarantool’s implementation of SWIM – Scalable Weakly-consistent Infection-style Process Group Membership Protocol. It is recommended for any type of Tarantool cluster where the number of nodes can be large. Its job is to discover and monitor the other members in the cluster and keep their information in a «member table». It works by sending and receiving, in a background event loop, periodically, via UDP, messages.

Each message has several parts, including:

The maximum message size is about 1500 bytes.

SWIM sends messages periodically to a random subset of the member table. SWIM processes replies from those members asynchronously.

Each entry in the member table has:

When a member fails to acknowledge a certain number of pings, its status is changed from «alive» to «suspected», that is, suspected of being dead. But SWIM tries to avoid false positives (misidentifying members as dead) which could happen when a member is overloaded and responds to pings too slowly, or when there is network trouble and packets can not go through some channels. When a member is suspected, SWIM randomly chooses other members and sends requests to them: «please ping this suspected member». This is called an indirect ping. Thus via different routes and additional hops the suspected member gets additional chances to reply, and thus «refute» the suspicion.

Because selection is random there is an even network load of about one message per member per protocol step, regardless of the cluster size. This is a major feature of SWIM. Because the protocol depends on members passing information on, also known as «gossiping», members do not need to broadcast messages to every member, which would cause a network load of N messages per member per protocol step, where N is the number of members in the cluster. However, selection is not entirely random, there is a preference for selecting least-recently-pinged members, like a round-robin.

Regarding the anti-entropy part of a message: this is necessary for maintaining the status in entries of the member table. Consider an example where two members, #1 and #2, are both alive. No events happen so only pings are being sent periodically. Then a third member, #3 appears. It knows about one of the existing members, #2. How can it discover the other member? Certainly #1 could notify #2 and #2 could notify #3, but messages go via UDP, so any notification event can be lost. However, regular messages containing «ping» and/or «event» also can contain an «anti-entropy» section, which is taken from a randomly-chosen part of the member table. So for this example, #2 will eventually randomly add to a regular message the anti-entropy note that #1 is alive, and thus #3 will discover #1 even though it did not receive a direct «I am alive» event message from #1.

Regarding the UUID part of an entry in the member table: this is necessary for stable identification, because UUID changes more rarely than URI (a combination of IP and port number). But if the UUID does change, SWIM will include both the new and old UUID in messages, so all other members will eventually learn about the new UUID and change the member table accordingly.

Regarding the payload part of a message: this is not always necessary, it is a feature which allows passing user-generated information via SWIM instead of via node-to-node communication. The swim module has methods for specifying a «payload», which is arbitrary user data with a maximum size of about 1.2 KB. The payload can be anything, and it will be eventually disseminated over the cluster and available at other members. Each member can have its own payload.

Messages can be encrypted. Encryption may not be necessary in a closed network but is necessary for safety if the cluster is on the public Internet. Users can specify an encryption algorithm, an encryption mode, and a private key. All parts of all messages (including ping, acknowledgment, event, payload, URI, and UUID) will be encrypted with that private key, as well as a random public key generated for each message to prevent pattern attacks.

In theory the event dissemination speed (the number of hops to pass information throughout the cluster) is O(log(cluster_size)). For that and other theoretical information see the Cornell University paper which originally described SWIM.

swim.new([cfg])

Create a new SWIM instance. A SWIM instance maintains a member table and interacts with other members. Multiple SWIM instances can be created in a single Tarantool process.

Параметры:
  • cfg (table) –

    an optional configuration parameter.

    If cfg is not specified or is nil, then the new SWIM instance is not bound to a socket and has nil attributes, so it cannot interact with other members and only a few methods are valid until swim_object:cfg() is called.

    If cfg is specified, then the effect is the same as calling s = swim.new() s:cfg(), except for generation. For configuration description see swim_object:cfg().

The generation part of cfg can only be specified during new(), it cannot be specified later during cfg(). Generation is part of incarnation. Usually generation is not specified because the default value (a timestamp) is sufficient, but if there is reason to mistrust timestamps (because the time is changed or because the instance is started on a different machine), then users may say swim.new({generation = <number>}). In that case the latest value should be persisted somehow (for example in a file, or in a space, or in a global service), and the new value must be greater than any previous value of generation.

возвращает:swim-object a swim object

Пример:

swim_object = swim.new({uri = 3333, uuid = '00000000-0000-1000-8000-000000000001', heartbeat_rate = 0.1})
object swim_object

A swim object is an object returned by swim.new(). It has methods: cfg(), delete(), is_configured(), size(), quit(), add_member(), remove_member(), probe_member(), broadcast(), set_payload(), set_payload_raw(), set_codec(), self(), member_by_uuid(), pairs().

swim_object:cfg(cfg)

Configure or reconfigure a SWIM instance.

Параметры:
  • cfg (table) – the options to describe instance behavior

The cfg table may have these components:

  • heartbeat_rate (double) – rate of sending round messages, in seconds. Setting heartbeat_rate to X does not mean that every member will be checked every X seconds, instead X is the protocol speed. Protocol period depends on member count and heartbeat_rate. Default = 1.

  • ack_timeout (double) – time in seconds after which a ping is considered to be unacknowledged. Default = 30.

  • gc_mode (enum) – dead member collection mode.

    If gc_mode == 'off' then SWIM never removes dead members from the member table (though users may remove them with swim_object:remove_member()), and SWIM will continue to ping them as if they were alive.

    If gc_mode == 'on' then SWIM removes dead members from the member table after one round.

    Default = 'on'.

  • uri (string or number) – either an 'ip:port' address, or just a port number (if ip is omitted then 127.0.0.1 is assumed). If port == 0, then the kernel will select any free port for the IP address.

  • uuid (string or cdata struct tt_uuid) – a value which should be unique among SWIM instances. Users may choose any value but the recommendation is: use box.cfg.instance_uuid, the Tarantool instance’s UUID.

All the cfg components are dynamic – swim_object:cfg() may be called more than once. If it is not being called for the first time and a component is not specified, then the component retains its previous value. If it is being called for the first time then uri and uuid are mandatory, since a SWIM instance cannot operate without URI and UUID.

swim_object:cfg() is atomic – if there is an error, then nothing changes.

возвращает:true if configuration succeeds
возвращает:nil, err if an error occurred. err is an error object

Пример:

swim_object:cfg({heartbeat_rate = 0.5})

After swim_object:cfg(), all other swim_object methods are callable.

.cfg

Expose all non-nil components of the read-only table which was set up or changed by swim_object:cfg().

Пример:

tarantool> swim_object.cfg
---
- gc_mode: off
  uri: 3333
  uuid: 00000000-0000-1000-8000-000000000001
...
swim_object:delete()

Delete a SWIM instance immediately. Its memory is freed, its member table entry is deleted, and it can no longer be used. Other members will treat this member as „dead“.

After swim_object:delete() any attempt to use the deleted instance will cause an exception to be thrown.

возвращает:none, this method does not fail

Example: swim_object:delete()

swim_object:is_configured()

Return false if a SWIM instance was created via swim.new() without an optional cfg argument, and was not configured with swim_object:cfg(). Otherwise return true.

возвращает:boolean result, true if configured, otherwise false

Example: swim_object:is_configured()

swim_object:size()

Return the size of the member table. It will be at least 1 because the «self» member is included.

возвращает:integer size

Example: swim_object:size()

swim_object:quit()

Leave the cluster.

This is a graceful equivalent of swim_object:delete() – the instance is deleted, but before deletion it sends to each member in its member table a message, that this instance has left the cluster, and should not be considered dead.

Other instances will mark such a member in their tables as „left“, and drop it after one round of dissemination.

Consequences to the caller are the same as after swim_object:delete() – the instance is no longer usable, and an error will be thrown if there is an attempt to use it.

возвращает:none, the method does not fail

Example: swim_object:quit()

swim_object:add_member(cfg)

Explicitly add a member into the member table.

This method is useful when a new member is joining the cluster and does not yet know what members already exist. In that case it can start interaction explicitly by adding the details about an already-existing member into its member table. Subsequently SWIM will discover other members automatically via messages from the already-existing member.

Параметры:
  • cfg (table) – description of the member

The cfg table has two mandatory components, uuid and uri, which have the same format as uuid and uri in the table for swim_object:cfg().

возвращает:true if member is added
возвращает:nil, err if an error occurred. err is an error object

Пример:

swim_member_object = swim_object:add_member({uuid = ..., uri = ...})
swim_object:remove_member(uuid)

Explicitly and immediately remove a member from the member table.

Параметры:
  • uuid (string-or-cdata-struct-tt_uuid) – UUID
возвращает:

true if member is removed
возвращает:

nil, err if an error occurred. err is an error object.

Example: swim_object:delete('00000000-0000-1000-8000-000000000001')

swim_object:probe_member(uri)

Send a ping request to the specified uri address. If another member is listening at that address, it will receive the ping, and respond with an ACK (acknowledgment) message containing information such as UUID. That information will be added to the member table.

swim_object:probe_member() is similar to swim_object:add_member(), but it does not require UUID, and it is not reliable because it uses UDP.

Параметры:
  • uri (string-or-number) – URI. Format is the same as for uri in swim_object:cfg().
возвращает:

true if member is pinged
возвращает:

nil, err if an error occurred. err is an error object.

Example: swim_object:probe_member(3333)

swim_object:broadcast([port])

Broadcast a ping request to all the network interfaces in the system.

swim_object:broadcast() is like swim_object:probe_member() to many members at once.

Параметры:
  • port (number) – All the sent ping requests have this port as destination port in their UDP headers. By default a currently bound port is used.
возвращает:

true if broadcast is sent
возвращает:

nil, err if an error occurred. err is an error object.

Пример:

tarantool> fiber = require('fiber')
---
...
tarantool> swim = require('swim')
---
...
tarantool> s1 = swim.new({uri = 3333, uuid = '00000000-0000-1000-8000-000000000001', heartbeat_rate = 0.1})
---
...
tarantool> s2 = swim.new({uri = 3334, uuid = '00000000-0000-1000-8000-000000000002', heartbeat_rate = 0.1})
---
...
tarantool> s1:size()
---
- 1
...
tarantool> s1:add_member({uri = s2:self():uri(), uuid = s2:self():uuid()})
---
- true
...
tarantool> s1:size()
---
- 1
...
tarantool> s2:size()
---
- 1
...

tarantool> fiber.sleep(0.2)
---
...
tarantool> s1:size()
---
- 2
...
tarantool> s2:size()
---
- 2
...
tarantool> s1:remove_member(s2:self():uuid()) s2:remove_member(s1:self():uuid())
---
...
tarantool> s1:size()
---
- 1
...
tarantool> s2:size()
---
- 1
...

tarantool> s1:probe_member(s2:self():uri())
---
- true
...
tarantool> fiber.sleep(0.1)
---
...
tarantool> s1:size()
---
- 2
...
tarantool> s2:size()
---
- 2
...
tarantool> s1:remove_member(s2:self():uuid()) s2:remove_member(s1:self():uuid())
---
...
tarantool> s1:size()
---
- 1
...
tarantool> s2:size()
---
- 1
...
tarantool> s1:broadcast(3334)
---
- true
...
tarantool> fiber.sleep(0.1)
---
...
tarantool> s1:size()
---
- 2
...

tarantool> s2:size()
---
- 2
...
swim_object:set_payload(payload)

Set a payload, as formatted data.

Payload is arbitrary user defined data up to 1200 bytes in size and disseminated over the cluster. So each cluster member will eventually learn what is the payload of other members in the cluster, because it is stored in the member table and can be queried with swim_member_object:payload().

Different members may have different payloads.

Параметры:
  • payload (object) – Arbitrary Lua object to disseminate. Set to nil to remove the payload, in which case it will be eventually removed on other instances. The object is serialized in MessagePack.
возвращает:

true if payload is set
возвращает:

nil, err if an error occurred. err is an error object

Пример:

swim_object:set_payload({field1 = 100, field2 = 200})
swim_object:set_payload_raw(payload[, size])

Set a payload, as raw data.

Sometimes a payload does not need to be a Lua object. For example, a user may already have a well formatted MessagePack object and just wants to set it as a payload. Or cdata needs to be exposed.

set_payload_raw allows setting a payload as is, without MessagePack serialization.

Параметры:
  • payload (string-or-cdata) – any value
  • size (number) – Payload size in bytes. If payload is string then size is optional, and if specified, then should not be larger than actual payload size. If size is less than actual payload size, then only the first size bytes of payload are used. If payload is cdata then size is mandatory.
возвращает:

true if payload is set
возвращает:

nil, err if an error occurred. err is an error object

Пример:

tarantool> tarantool> ffi = require('ffi')
---
...
tarantool> fiber = require('fiber')
---
...
tarantool> swim = require('swim')
---
...
tarantool> s1 = swim.new({uri = 0, uuid = '00000000-0000-1000-8000-000000000001', heartbeat_rate = 0.1})
---
...
tarantool> s2 = swim.new({uri = 0, uuid = '00000000-0000-1000-8000-000000000002', heartbeat_rate = 0.1})
---
...
tarantool> s1:add_member({uri = s2:self():uri(), uuid = s2:self():uuid()})
---
- true
...
tarantool> s1:set_payload({a = 100, b = 200})
---
- true
...
tarantool> s2:set_payload('any payload')
---
- true
...
tarantool> fiber.sleep(0.2)
---
...
tarantool> s1_view = s2:member_by_uuid(s1:self():uuid())
---
...
tarantool> s2_view = s1:member_by_uuid(s2:self():uuid())
---
...
tarantool> s1_view:payload()
---
- {'a': 100, 'b': 200}
...
tarantool> s2_view:payload()
---
- any payload
...
tarantool> cdata = ffi.new('char[?]', 2)
---
...
tarantool> cdata[0] = 1
---
...
tarantool> cdata[1] = 2
---
...
tarantool> s1:set_payload_raw(cdata, 2)
---
- true
...
tarantool> fiber.sleep(0.2)
---
...
tarantool> cdata, size = s1_view:payload_cdata()
---
...
tarantool> cdata[0]
---
- 1
...
tarantool> cdata[1]
---
- 2
...
tarantool> size
---
- 2
...
swim_object:set_codec(codec_cfg)

Enable encryption for all following messages.

For a brief description of encryption algorithms see «enum_crypto_algo» and «enum crypto_mode» in the Tarantool source code file crypto.h.

When encryption is enabled, all the messages are encrypted with a chosen private key, and a randomly generated and updated public key.

Параметры:
  • codec_cfg (table) – description of the encryption

The components of the codec_cfg table may be:

  • algo (string) – encryption algorithm name. All the names in module crypto are supported: „aes128“, „aes192“, „aes256“, „des“. Specify „none“ to disable encryption.

  • mode (string) – encryption algorithm mode. All the modes in module crypto are supported: „ecb“, „cbc“, „cfb“, „ofb“. Default = „cbc“.

  • key (cdata or string) – a private secret key which is kept secret and should never be stored hard-coded in source code.

  • key_size (integer) – size of the key in bytes.

    key_size is mandatory if key is cdata.

    key_size is optional if key is string, and if key_size is shorter than than actual key size then the key is truncated.

All of algo, mode, key, and key_size should be the same for all SWIM instances, so that members can understand each others“ messages.

Пример;

tarantool> tarantool> swim = require('swim')
---
...
tarantool> s1 = swim.new({uri = 0, uuid = '00000000-0000-1000-8000-000000000001'})
---
...
tarantool> s1:set_codec({algo = 'aes128', mode = 'cbc', key = '1234567812345678'})
---
- true
...
swim_object:self()

Return a swim member object (of self) from the member table, or from a cache containing earlier results of swim_object:self() or swim_object:member_by_uuid() or swim_object:pairs().

возвращает:swim member object, not nil because self() will not fail

Example: swim_member_object = swim_object:self()

swim_object:member_by_uuid(uuid)

Return a swim member object (given UUID) from the member table, or from a cache containing earlier results of swim_object:self() or swim_object:member_by_uuid() or swim_object:pairs().

Параметры:
  • uuid (string-or-cdata-struct-tt-uuid) – UUID
возвращает:

swim member object, or nil if not found

Пример:

swim_member_object = swim_object:member_by_uuid('00000000-0000-1000-8000-000000000001')
swim_object:pairs()

Set up an iterator for returning swim member objects from the member table, or from a cache containing earlier results of swim_object:self() or swim_object:member_by_uuid() or swim_object:pairs().

swim_object:pairs() should be in a „for“ loop, and there should only be one iterator in operation at one time. (The iterator is implemented in an extra light fashion so only one iterator object is available per SWIM instance.)

Параметры:
  • generator+object+key (varies) – as for any Lua pairs() iterators. generator function, iterator object (a swim member object), and initial key (a UUID).

Пример:

tarantool> fiber = require('fiber')
---
...
tarantool> swim = require('swim')
---
...
tarantool> s1 = swim.new({uri = 0, uuid = '00000000-0000-1000-8000-000000000001', heartbeat_rate = 0.1})
---
...
tarantool> s2 = swim.new({uri = 0, uuid = '00000000-0000-1000-8000-000000000002', heartbeat_rate = 0.1})
---
...
tarantool> s1:add_member({uri = s2:self():uri(), uuid = s2:self():uuid()})
---
- true
...
tarantool> fiber.sleep(0.2)
---
...
tarantool> s1:self()
---
- uri: 127.0.0.1:55845
  status: alive
  incarnation: cdata {generation = 1569353431853325ULL, version = 1ULL}
  uuid: 00000000-0000-1000-8000-000000000001
  payload_size: 0
...
tarantool> s1:member_by_uuid(s1:self():uuid())
---
- uri: 127.0.0.1:55845
  status: alive
  incarnation: cdata {generation = 1569353431853325ULL, version = 1ULL}
  uuid: 00000000-0000-1000-8000-000000000001
  payload_size: 0
...
tarantool> s1:member_by_uuid(s2:self():uuid())
---
- uri: 127.0.0.1:53666
  status: alive
  incarnation: cdata {generation = 1569353431865138ULL, version = 1ULL}
  uuid: 00000000-0000-1000-8000-000000000002
  payload_size: 0
...
tarantool> t = {}
---
...
tarantool> for k, v in s1:pairs() do table.insert(t, {k, v}) end
---
...
tarantool> t
---
- - - 00000000-0000-1000-8000-000000000002
    - uri: 127.0.0.1:53666
      status: alive
      incarnation: cdata {generation = 1569353431865138ULL, version = 1ULL}
      uuid: 00000000-0000-1000-8000-000000000002
      payload_size: 0
  - - 00000000-0000-1000-8000-000000000001
    - uri: 127.0.0.1:55845
      status: alive
      incarnation: cdata {generation = 1569353431853325ULL, version = 1ULL}
      uuid: 00000000-0000-1000-8000-000000000001
      payload_size: 0
...
object swim_member_object

Methods swim_object:member_by_uuid(), swim_object:self(), and swim_object:pairs() return swim member objects.

A swim member object has methods for reading its attributes: status(), uuid, uri(), incarnation(), payload_cdata, payload_str(), payload(), is_dropped().

swim_member_object:status()

Return the status, which may be „alive“, „suspected“, „left“, or „dead“.

возвращает:string „alive“ | „suspected“ | „left“ | dead“
swim_member_object:uuid()

Return the UUID as cdata struct tt_uuid.

возвращает:cdata-struct-tt-uuid UUID
swim_member_object:uri()

Return the URI as a string „ip:port“. Via this method a user can learn a real assigned port, if port = 0 was specified in swim_object:cfg().

возвращает:string ip:port
swim_member_object:incarnation()

Return a cdata object with the incarnation. The cdata object has two attributes: incarnation().generation and incarnation().version.

Incarnations can be compared to each other with any comparison operator (==, <, >, <=, >=, ~=).

Incarnations, when printed, will appear as strings with both generation and version.

возвращает:cdata incarnation
swim_member_object:payload_cdata()

Return member’s payload.

возвращает:pointer-to-cdata payload and size in bytes
swim_member_object:payload_str()

Return payload as a string object. Payload is not decoded. It is just returned as a string instead of cdata. If payload was not specified by swim_object:set_payload() or by swim_object:set_payload_raw(), then its size is 0 and nil is returned.

возвращает:string-object payload, or nil if there is no payload
swim_member_object:payload()

Since the swim module is a Lua module, a user is likely to use Lua objects as a payload – tables, numbers, strings etc. And it is natural to expect that swim_member_object:payload() should return the same object which was passed into swim_object:set_payload() by another instance. swim_member_object:payload() tries to interpret payload as MessagePack, and if that fails then it returns the payload as a string.

swim_member_object:payload() caches its result. Therefore only the first call actually decodes cdata payload. All following calls return a pointer to the same result, unless payload is changed with a new incarnation. If payload was not specified (its size is 0), then nil is returned.

swim_member_object:is_dropped()

Returns true if this member object is a stray reference to a member which has already been dropped from the member table.

возвращает:boolean true if member is dropped, otherwise false

Пример:

tarantool> swim = require('swim')
---
...
tarantool> s = swim.new({uri = 0, uuid = '00000000-0000-1000-8000-000000000001'})
---
...
tarantool> self = s:self()
---
...
tarantool> self:status()
---
- alive
...
tarantool> self:uuid()
---
- 00000000-0000-1000-8000-000000000001
...
tarantool> self:uri()
---
- 127.0.0.1:56367
...
tarantool> self:incarnation()
---
- - cdata {generation = 1569354463981551ULL, version = 1ULL}
...
tarantool> self:is_dropped()
---
- false
...
tarantool> s:set_payload_raw('123')
---
- true
...
tarantool> self:payload_cdata()
---
- 'cdata<const char *>: 0x0103500050'
- 3
...
tarantool> self:payload_str()
---
- '123'
...
tarantool> s:set_payload({a = 100})
---
- true
...
tarantool> self:payload_cdata()
---
- 'cdata<const char *>: 0x0103500050'
- 4
...
tarantool> self:payload_str()
---
- !!binary gaFhZA==
...
tarantool> self:payload()
---
- {'a': 100}
...
swim_member_object:on_member_event(trigger-function[, ctx])

Create an «on_member trigger». The trigger-function will be executed when a member in the member table is updated.

Параметры:
  • trigger-function (function) – this will become the trigger function
  • ctx (cdata) – (optional) this will be passed to trigger-function
возвращает:

nil or function pointer.

The trigger-function should have three parameter declarations (Tarantool will pass values for them when it invokes the function):

  • the member which is having the member event,
  • the event object,
  • the ctx which will be the same value as what is passed to swim_object:on_member_event.

A member event is any of:

  • appearance of a new member,
  • drop of an existing member, or
  • update of an existing member.

An event object is an object which the trigger-function can use for determining what type of member event has happened. The object’s methods – such as is_new_status(), is_new_uri(), is_new_incarnation(), is_new_payload(), is_drop() – return boolean values.

A member event may have more than one associated trigger. Triggers are executed sequentially. Therefore if a trigger function causes yields or sleeps, other triggers may be forced to wait. However, since trigger execution is done in a separate fiber, SWIM itself is not forced to wait.

Example of an on-member trigger function:

tarantool> swim = require('swim')

local function on_event(member, event, ctx)
    if event:is_new() then
        ...
    elseif event:is_drop() then
        ...
    end

    if event:is_update() then
        -- All next conditions can be
        -- true simultaneously.
        if event:is_new_status() then
...
        end
        if event:is_new_uri() then
...
        end
        if event:is_new_incarnation() then
...
        end
        if event:is_new_payload() then
...
        end
    end
end

Notice in the above example that the function is ready for the possibility that multiple events can happen simultaneously for a single trigger activation. is_new() and is_drop() can not both be true, but is_new() and is_update() can both be true, or is_drop() and is_update() can both be true. Multiple simultaneous events are especially likely if there are many events and trigger functions are slow – in that case, for example, a member might be added and then updated after a while, and then after a while there will be a single trigger activation.

Also: is_new() and is_new_payload() can both be true. This case is not due to trigger functions that are slow. It occurs because «omitted payload» and «size-zero payload» are not the same thing. For example: when a ping is received, a new member might be added, but ping messages do not include payload. The payload will appear later in a different message. If that is important for the application, then the function should not assume when is_new() is true that the member already has a payload, and should not assume that payload size says something about the payload’s presence or absence.

Also: functions should not assume that is_new() and is_drop() will always be seen. If a new member appears but then is dropped before its appearance has caused a trigger activation, then there will be no trigger activation.

is_new_generation() will be true if the generation part of incarnation changes. is_new_version() will be true if the version part of incarnation changes. is_new_incarnation() will be true if either the generation part or the version part of incarnation changes. For example a combination of these methods can be used within a user-defined trigger to check whether a process has restarted, or a member has changed …

swim = require('swim')
s = swim.new()
s:on_member_event(function(m, e)
...
    if e:is_new_incarnation() then
        if e:is_new_generation() then
            -- Process restart.
        end
        if e:is_new_version() then
            -- Process version update. It means
            -- the member is somehow changed.
        end
    end
end
swim_member_object:on_member_event(nil, old-trigger)

Delete an on-member trigger.

Параметры:
  • old-trigger (function) – old-trigger

The old-trigger value should be the value returned by on_member_event(trigger-function[, ctx]).

swim_member_object:on_member_event(new-trigger, old-trigger[, ctx])

This is a variation of on_member_event(new-trigger, [, ctx]).

The additional parameter is old-trigger. Instead of adding the new-trigger at the end of a list of triggers, this function will replace the entry in the list of triggers that matches old-trigger. The position within a list may be important because triggers are activated sequentially starting with the first trigger in the list.

The old-trigger value should be the value returned by on_member_event(trigger-function[, ctx]).

swim_member_object:on_member_event()

Return the list of on-member triggers.

SWIM internals

The SWIM internals section is not necessary for programmers who wish to use the SWIM module, it is for programmers who wish to change or replace the SWIM module.

The SWIM wire protocol is open, will be backward compatible in case of any changes, and can be implemented by users who wish to simulate their own SWIM cluster members because they use another language than Lua, or another environment unrelated to Tarantool. The protocol is encoded as MsgPack.

SWIM packet structure:

+-----------------Public data, not encrypted------------------+
|                                                             |
|      Initial vector, size depends on chosen algorithm.      |
|                   Next data is encrypted.                   |
|                                                             |
+----------Meta section, handled by transport level-----------+
| map {                                                       |
|     0 = SWIM_META_TARANTOOL_VERSION: uint, Tarantool        |
|                                      version ID,            |
|     1 = SWIM_META_SRC_ADDRESS: uint, ip,                    |
|     2 = SWIM_META_SRC_PORT: uint, port,                     |
|     3 = SWIM_META_ROUTING: map {                            |
|         0 = SWIM_ROUTE_SRC_ADDRESS: uint, ip,               |
|         1 = SWIM_ROUTE_SRC_PORT: uint, port,                |
|         2 = SWIM_ROUTE_DST_ADDRESS: uint, ip,               |
|         3 = SWIM_ROUTE_DST_PORT: uint, port                 |
|     }                                                       |
| }                                                           |
+-------------------Protocol logic section--------------------+
| map {                                                       |
|     0 = SWIM_SRC_UUID: 16 byte UUID,                        |
|                                                             |
|                 AND                                         |
|                                                             |
|     2 = SWIM_FAILURE_DETECTION: map {                       |
|         0 = SWIM_FD_MSG_TYPE: uint, enum swim_fd_msg_type,  |
|         1 = SWIM_FD_GENERATION: uint,                       |
|         2 = SWIM_FD_VERSION: uint                           |
|     },                                                      |
|                                                             |
|               OR/AND                                        |
|                                                             |
|     3 = SWIM_DISSEMINATION: array [                         |
|         map {                                               |
|             0 = SWIM_MEMBER_STATUS: uint,                   |
|                                     enum member_status,     |
|             1 = SWIM_MEMBER_ADDRESS: uint, ip,              |
|             2 = SWIM_MEMBER_PORT: uint, port,               |
|             3 = SWIM_MEMBER_UUID: 16 byte UUID,             |
|             4 = SWIM_MEMBER_GENERATION: uint,               |
|             5 = SWIM_MEMBER_VERSION: uint,                  |
|             6 = SWIM_MEMBER_PAYLOAD: bin                    |
|         },                                                  |
|         ...                                                 |
|     ],                                                      |
|                                                             |
|               OR/AND                                        |
|                                                             |
|     1 = SWIM_ANTI_ENTROPY: array [                          |
|         map {                                               |
|             0 = SWIM_MEMBER_STATUS: uint,                   |
|                                     enum member_status,     |
|             1 = SWIM_MEMBER_ADDRESS: uint, ip,              |
|             2 = SWIM_MEMBER_PORT: uint, port,               |
|             3 = SWIM_MEMBER_UUID: 16 byte UUID,             |
|             4 = SWIM_MEMBER_GENERATION: uint,               |
|             5 = SWIM_MEMBER_VERSION: uint,                  |
|             6 = SWIM_MEMBER_PAYLOAD: bin                    |
|         },                                                  |
|         ...                                                 |
|     ],                                                      |
|                                                             |
|               OR/AND                                        |
|                                                             |
|     4 = SWIM_QUIT: map {                                    |
|         0 = SWIM_QUIT_GENERATION: uint,                     |
|         1 = SWIM_QUIT_VERSION: uint                         |
|     }                                                       |
| }                                                           |
+-------------------------------------------------------------+

The Initial vector section appears only when encryption is enabled. This section contains a public key. For example, for AES algorithms it is a 16-byte initial vector stored as is. When no encryption is used, the section size is 0.

The later sections (Meta and Protocol Logic) are encrypted as one big data chunk if encryption is enabled.

The Meta section handles routing and protocol versions compatibility. It works at the „transport“ level of the SWIM protocol, and is always present. Keys in the meta section are:

The Protocol logic section handles SWIM logical protocol steps and actions.

Following SWIM_SRC_UUID there are four possible subsections: SWIM_FAILURE_DETECTION, SWIM_DISSEMINATION, SWIM_ANTI_ENTROPY, SWIM_QUIT. Any or all of these subsections may be present. A connector should be ready to handle any combination.

The incarnation is a 128-bit cdata value which is part of each member’s configuration and is present in most messages. It has two parts: generation and version.

Generation is persistent. By default it has the number of microseconds since the epoch (compare the value returned by clock_realtime64()). Optionally a user can set generation during new().

Version is volatile. It is initially 0. It is incremented automatically every time that a change occurs.

The incarnation, or sometimes the version alone, is useful for deciding to ignore obsolete messages, for updating a member’s attributes on remote nodes, and for refuting messages that say a member is dead.

If the member’s incarnation is less than the locally stored incarnation, then the message is obsolete. This can happen because UDP allows reordering and duplication.

If the member’s incarnation in a message is greater than the locally stored incarnation, then most of its attributes (IP, port, status) should be updated with the values received in the message. However, the payload attribute should not be updated unless it is present in the message. Because of its relatively large size, payload is not always included in every message.

Refutation usually happens when a false-positive failure detection has happened. In such a case the member thought to be dead receives that information from other members, increases its own incarnation, and spreads a message saying the member is alive (a «refutation»).

Note: in the original version of Tarantool SWIM, and in the original SWIM specification, there is no generation and the incarnation consists of only the version. Generation was added because it is useful for detecting obsolete messages left over from a previous life of an instance that has restarted.

Модуль table

Модуль table включает в себя всё из стандартной библиотеки для работы с таблицами в Lua, а также некоторые расширения специально для Tarantool.

Write table to see the list of functions:

В данном разделе мы рассматриваем только дополнительную функцию, добавленную разработчиками Tarantool: deepcopy.

table.deepcopy(input-table)

Возврат детальной копии таблицы – копии, которая включает в себя вложенные структуры любой глубины и не зависит от указателей, копируется содержимое.

Параметры:
  • input-table – таблица для копирования
Возвращается:

копия таблицы
Тип возвращаемого значения:
 

таблица

Пример:

tarantool> input_table = {1,{'a','b'}}
---
...

tarantool> output_table = table.deepcopy(input_table)
---
...

tarantool> output_table
---
- - 1
  - - a
    - b
...
table.sort(input-table[, comparison-function])

Размещение содержимого введенной таблицы в отсортированном порядке.

В базовой сортировке в Lua, table.sort, есть функция сравнения, которая используется по умолчанию: function (a, b) return a < b end.

Эта стандартная функция эффективна. Однако иногда пользователям Tarantool может понадобиться эквивалент table.sort со следующими функциями:

  1. If the table contains nils, except nils at the end, the results must still be correct. That is not the case with the default tarantool_sort, and it cannot be fixed by making a comparison that checks whether a and b are nil. (Before trying certain Internet suggestions, test with {1, nil, 2, -1, 44, 1e308, nil, 2, nil, nil, 0}.
  2. If strings are to be sorted in a language-aware way, there must be a parameter for collation.
  3. If the table has a mix of types, then they must be sorted as booleans, then numbers, then strings, then byte arrays.

Поскольку все эти функции доступны в спейсах Tarantool, решение простое: создайте временный спейс в Tarantool, поместите в него содержимое таблицы, извлеките из него кортежи по порядку и перезапишите таблицу.

Тогда tarantool_sort() сделает то же самое, что и table.sort, но с этими дополнительными функциями. Это не быстрый способ, который требует прав на базу данных, поэтому его следует использовать только при необходимости дополнительных функций.

Пример:

function tarantool_sort(input_table, collation)
    local c = collation or 'binary'
    local tmp_name = 'Temporary_for_tarantool_sort'
    pcall(function() box.space[tmp_name]:drop() end)
    box.schema.space.create(tmp_name, {temporary = true})
    box.space[tmp_name]:create_index('I')
    box.space[tmp_name]:create_index('I2',
                                     {unique = false,
                                      type='tree',
                                      parts={{2, 'scalar',
                                              collation = c,
                                              is_nullable = true}}})
    for i = 1, table.maxn(input_table) do
        box.space[tmp_name]:insert{i, input_table[i]}
    end
    local t = box.space[tmp_name].index.I2:select()
    for i = 1, table.maxn(input_table) do
        input_table[i] = t[i][2]
    end
    box.space[tmp_name]:drop()
  end

For example, suppose table t = {1, 'A', -88.3, nil, true, 'b', 'B', nil, 'À'}.

After tarantool_sort(t, 'unicode_ci') t contains {nil, nil, true, -88.3, 1, 'A', 'À', 'b', 'B'}.

Модуль tap

Общие сведения

The tap module streamlines the testing of other modules. It allows writing of tests in the TAP protocol. The results from the tests can be parsed by standard TAP-analyzers so they can be passed to utilities such as prove. Thus, one can run tests and then use the results for statistics, decision-making, and so on.

Справочник по API

Имя Назначение
tap.test() Инициализация
taptest:test() Создание подтеста и вывод результатов
taptest:plan() Указание количества проводимых тестов
taptest:check() Проверка количества выполненных тестов
taptest:diag() Отображение сообщения диагностики
taptest:ok() Оценка состояния и отображение сообщения
taptest:fail() Оценка состояния и отображение сообщения
taptest:skip() Оценка состояния и отображение сообщения
taptest:is() Проверка равенства двух аргументов
taptest:isnt() Проверка отличий двух аргументов
taptest:is_deeply() Рекурсивная проверка равенства двух аргументов
taptest:like() Проверка соответствия аргумента шаблону
taptest:unlike() Проверка отличия аргумента от шаблона
taptest:isnil()
taptest:isstring()
taptest:isnumber()
taptest:istable()
taptest:isboolean()
taptest:isudata()
taptest:iscdata()		 Проверка соответствия значения определенному типу
taptest.strict Flag, true if comparisons with nil should be strict
tap.test(test-name)

Инициализация.

Результатом tap.test является объект, который будет называться taptest в ходе данного разбора, что необходимо для taptest:plan() и всех остальных методов.

Параметры:
  • test-name (string) – произвольное имя для результата теста.
возвращает:

taptest
тип возвращаемого значения:
 

таблица

 
tap = require('tap')
taptest = tap.test('test-name')
object taptest
taptest:test(test-name, func)

Создание подтеста (если не указан аргумент func) или (если указаны все аргументы) создание подтеста, выполнение тестовой функции и вывод результата.

См. пример.

Параметры:
  • name (string) – произвольное имя для результата теста.
  • fun (function) – выполняемая тестовая логика.
возвращает:

taptest
тип возвращаемого значения:
 

userdata или строка
taptest:plan(count)

Указание количества проводимых тестов.

Параметры:
  • count (number) –
возвращает:

nil
taptest:check()

Проверка количества выполненных тестов.

Выведенный результат будет включать в себя сообщение: # bad plan: ..., если количество выполненных тестов не равно количеству тестов, указанному в taptest:plan(...). (Это собственная функция Tarantool: сообщения типа «bad plan» не входят в стандарт TAP13.)

Такую проверку следует проводить только по завершении всех запланированных тестов, поэтому как правило, taptest:check() появится лишь в конце скрипта. Тем не менее, в качестве расширения Tarantool, taptest:check() может появиться в начале любого подтеста. Таким образом, проверка появится в трех случаях:

  • при вызове taptest:check() в конце скрипта,
  • при вызове функции, которая заканчивается вызовом taptest:check(),
  • или при вызове taptest:test(„…“, имя-функции-подтеста), где функция подтеста не обязана заканчиваться на taptest:check(), поскольку ее можно вызвать по окончании подтеста.
возвращает:true (правда) или false (ложь).
тип возвращаемого значения:
 boolean (логический)
taptest:diag(message)

Отображение сообщения диагностики.

Параметры:
  • message (string) – отображаемое сообщение.
возвращает:

nil
taptest:ok(condition, test-name)

Это базовая функция, которая используется другими функциями. В зависимости от условия condition, выводится „ok“ или „not ok“ вместе с отладочной информацией. Отображается сообщение.

Параметры:
  • condition (boolean) – выражение, которое либо true (правда), либо false (ложь)
  • test-name (string) – имя теста
возвращает:

true (правда) или false (ложь).
тип возвращаемого значения:
 

boolean (логический)

Пример:

tarantool> taptest:ok(true, 'x')
ok - x
---
- true
...
tarantool> tap = require('tap')
---
...
tarantool> taptest = tap.test('test-name')
TAP version 13
---
...
tarantool> taptest:ok(1 + 1 == 2, 'X')
ok - X
---
- true
...
taptest:fail(test-name)

taptest:fail('x') – аналог taptest:ok(false, 'x'). Отображается сообщение.

Параметры:
  • test-name (string) – имя теста
возвращает:

true (правда) или false (ложь).
тип возвращаемого значения:
 

boolean (логический)
taptest:skip(message)

taptest:skip('x') – аналог taptest:ok(true, 'x' .. '# skip'). Отображается сообщение.

Параметры:
  • test-name (string) – имя теста
возвращает:

nil

Пример:

tarantool> taptest:skip('message')
ok - message # skip
---
- true
...
taptest:is(got, expected, test-name)

Проверка равенства первого аргумента второму аргументу. Отображается подробное сообщение, если результатом будет false (ложь).

Параметры:
  • got (number) – фактический результат
  • expected (number) – ожидаемый результат
  • test-name (string) – имя теста
возвращает:

true (правда) или false (ложь).
тип возвращаемого значения:
 

boolean (логический)
taptest:isnt(got, expected, test-name)

Отрицание taptest:is().

Параметры:
  • got (number) – фактический результат
  • expected (number) – ожидаемый результат
  • test-name (string) – имя теста
возвращает:

true (правда) или false (ложь).
тип возвращаемого значения:
 

boolean (логический)
taptest:is_deeply(got, expected, test-name)

Recursive version of taptest:is(...), which can be used to compare tables as well as scalar values.

возвращает:

true (правда) или false (ложь).
тип возвращаемого значения:
 

boolean (логический)
Параметры:
  • got (lua-value) – фактический результат
  • expected (lua-value) – ожидаемый результат
  • test-name (string) – имя теста
taptest:like(got, expected, test-name)

Проверка совпадения строки с шаблоном. Ok, если найдено совпадение.

возвращает:

true (правда) или false (ложь).
тип возвращаемого значения:
 

boolean (логический)
Параметры:
  • got (lua-value) – фактический результат
  • expected (lua-value) – шаблон
  • test-name (string) – имя теста
 
test:like(tarantool.version, '^[1-9]', "version")
taptest:unlike(got, expected, test-name)

Отрицание taptest:like().

Параметры:
  • got (number) – фактический результат
  • expected (number) – шаблон
  • test-name (string) – имя теста
возвращает:

true (правда) или false (ложь).
тип возвращаемого значения:
 

boolean (логический)
taptest:isnil(value, message, extra)
taptest:isstring(value, message, extra)
taptest:isnumber(value, message, extra)
taptest:istable(value, message, extra)
taptest:isboolean(value, message, extra)
taptest:isudata(value, utype, message, extra)
taptest:iscdata(value, ctype, message, extra)

Проверка соответствия значения определенному типу. Отображается длинное сообщение, если значение не принадлежит указанному типу.

Параметры:
  • value (lua-value) – value the type of which is to be checked
  • utype (string) – type of data that a passed value should have
  • ctype (string) – type of data that a passed value should have
  • message (string) – text that will be shown to the user in case of failure
возвращает:

true (правда) или false (ложь).
тип возвращаемого значения:
 

boolean (логический)

 
test:iscdata(slab_info.quota_size, ffi.typeof('uint64_t'), 'memcached.slab.info().quota_size returns a cdata')
taptest.strict

Set taptest.strict=true if taptest:is() and taptest:isnt() and taptest:is_deeply() must be compared strictly with nil. Set taptest.strict=false if nil and box.NULL both have the same effect.

The default is false. For example, if and only if taptest.strict=true has happened, then taptest:is_deeply({a = box.NULL}, {}) will return false.

Since v. 2.8.3, taptest.strict is inherited in all subtests:

t = require('tap').test('123')
t.strict = true

t:is_deeply({a = box.NULL}, {}) -- false

t:test('subtest', function(t)
    t:is_deeply({a = box.NULL}, {}) -- also false
end)

Пример

Для выполнения данного примера поместите скрипт в файл под названием ./tap.lua, затем сделайте tap.lua выполняемым файлом с помощью команды chmod a+x ./tap.lua, а затем выполните его, используя Tarantool в качестве обработчика скриптов после выполнения команды ./tap.lua.

#!/usr/bin/tarantool
local tap = require('tap')
test = tap.test("my test name")
test:plan(2)
test:ok(2 * 2 == 4, "2 * 2 is 4")
test:test("some subtests for test2", function(test)
    test:plan(2)
    test:is(2 + 2, 4, "2 + 2 is 4")
    test:isnt(2 + 3, 4, "2 + 3 is not 4")
end)
test:check()

Результатом вышеприведенного скрипта будет примерно следующее:

TAP version 13
1..2
ok - 2 * 2 is 4
    # Some subtests for test2
    1..2
    ok - 2 + 2 is 4,
    ok - 2 + 3 is not 4
    # Some subtests for test2: end
ok - some subtests for test2

Модуль tarantool

Выполнив команду require('tarantool'), можно получить ответы на вопросы о том, как был собран Tarantool-сервер, например, какие флаги были использованы, или какая версия компилятора использовалась.

Кроме того, можно проверить время работы и версию сервера, а также идентификатор процесса. Эту информацию также можно получить с помощью box.info(), но рекомендуется использовать модуль tarantool.

Пример:

tarantool> tarantool = require('tarantool')
---
...
tarantool> tarantool
---
- version: 2.10.4-0-g816000e
  build:
    target: Darwin-x86_64-Release
    options: cmake . -DCMAKE_INSTALL_PREFIX=/usr/local/Cellar/tarantool/2.10.4 -DENABLE_BACKTRACE=ON
    linking: dynamic
    mod_format: dylib
    flags: ' -fexceptions -funwind-tables -fno-common -fopenmp -msse2 -Wformat -Wformat-security
      -Werror=format-security -fstack-protector-strong -fPIC -fmacro-prefix-map=/tmp/tarantool-20221113-6655-1clb1lj/tarantool-2.10.4=.
      -std=c11 -Wall -Wextra -Wno-strict-aliasing -Wno-char-subscripts -Wno-format-truncation
      -Wno-gnu-alignof-expression -Wno-cast-function-type'
    compiler: Clang-14.0.0.14000029
  pid: 'function: 0x0102df34f8'
  package: Tarantool
  uptime: 'function: 0x0102df34c0'
...
tarantool> tarantool.pid()
---
- 30155
...
tarantool> tarantool.uptime()
---
- 108.64641499519
...

Tarantool includes parts of tzdata package and uses its database for a correct time zone support. Since 3.2.0, you can get a used version of tzdata:

tarantool> tarantool.build.tzdata_version
---
- 2022a
...

Модуль uri

Общие сведения

The URI module provides functions that convert URI strings into their components, or turn components into URI strings, for example:

local uri = require('uri')

parsed_uri = uri.parse('https://www.tarantool.io/doc/latest/reference/reference_lua/http/#api-reference')
--[[
---
- host: www.tarantool.io
  fragment: api-reference
  scheme: https
  path: /doc/latest/reference/reference_lua/http/
...
--]]

formatted_uri = uri.format({ scheme = 'https',
                             host = 'www.tarantool.io',
                             path = '/doc/latest/reference/reference_lua/http/',
                             fragment = 'api-reference' })
--[[
---
- https://www.tarantool.io/doc/latest/reference/reference_lua/http/#api-reference
...
--]]

You can also use this module to encode and decode arbitrary strings using the specified encoding options.

API Reference

Below is a list of uri functions, properties, and related objects.

Functions  
uri.parse() Получение таблицы URI-компонентов
uri.format() Construct a URI from the specified components
uri.escape() Encode a string using the specified encoding options
uri.unescape() Decode a string using the specified encoding options
Properties  
uri.RFC3986 Encoding options that use unreserved symbols defined in RFC 3986
uri.PATH Options used to encode the path URI component
uri.PATH_PART Options used to encode specific path parts
uri.QUERY Options used to encode the query URI component
uri.QUERY_PART Options used to encode specific query parts
uri.FRAGMENT Options used to encode the fragment URI component
uri.FORM_URLENCODED Options used to encode application/x-www-form-urlencoded form parameters
Related objects  
uri_components URI components
uri_encoding_opts URI encoding options

Functions

uri.parse(uri-string)

Parse a URI string into components.

See also: uri.format()

Параметры:
  • uri-string (string) – a URI string
возвращает:

a URI components table (see uri_components)
тип возвращаемого значения:
 

table

Пример:

local uri = require('uri')

parsed_uri = uri.parse('https://www.tarantool.io/doc/latest/reference/reference_lua/http/#api-reference')
--[[
---
- host: www.tarantool.io
  fragment: api-reference
  scheme: https
  path: /doc/latest/reference/reference_lua/http/
...
--]]
uri.format(uri_components[, include_password])

Construct a URI from the specified components.

See also: uri.parse()

Параметры:
  • uri_components (table) – a series of name=value pairs, one for each component (see uri_components)
  • include_password (boolean) – specify whether the password component is rendered in clear text; otherwise, it is omitted
возвращает:

URI string
тип возвращаемого значения:
 

строка

Пример:

local uri = require('uri')

formatted_uri = uri.format({ scheme = 'https',
                             host = 'www.tarantool.io',
                             path = '/doc/latest/reference/reference_lua/http/',
                             fragment = 'api-reference' })
--[[
---
- https://www.tarantool.io/doc/latest/reference/reference_lua/http/#api-reference
...
--]]
uri.escape(string[, uri_encoding_opts])

Since: 2.11.0

Encode a string using the specified encoding options.

By default, uri.escape() uses encoding options defined by the uri.RFC3986 table. If required, you can customize encoding options using the uri_encoding_opts optional parameter, for example:

  • Pass the predefined set of options targeted for encoding a specific URI part (for example, uri.PATH or uri.QUERY).
  • Pass custom encoding options using the uri_encoding_opts object.
Параметры:
  • string – a string to encode
  • uri_encoding_opts (table) – encoding options (optional, see uri_encoding_opts)
возвращает:

an encoded string
тип возвращаемого значения:
 

строка

Example 1:

This example shows how to encode a string using the default encoding options.

local uri = require('uri')

escaped_string = uri.escape('C++')
--[[
---
- C%2B%2B
...
--]]

Example 2:

This example shows how to encode a string using the uri.FORM_URLENCODED encoding options.

local uri = require('uri')

escaped_string_url_enc = uri.escape('John Smith', uri.FORM_URLENCODED)
--[[
---
- John+Smith
...
--]]

Example 3:

This example shows how to encode a string using custom encoding options.

local uri = require('uri')

local escape_opts = {
    plus = true,
    unreserved = uri.unreserved("a-z")
}
escaped_string_custom = uri.escape('Hello World', escape_opts)
--[[
---
- '%48ello+%57orld'
...
--]]
uri.unescape(string[, uri_encoding_opts])

Since: 2.11.0

Decode a string using the specified encoding options.

By default, uri.escape() uses encoding options defined by the uri.RFC3986 table. If required, you can customize encoding options using the uri_encoding_opts optional parameter, for example:

  • Pass the predefined set of options targeted for encoding a specific URI part (for example, uri.PATH or uri.QUERY).
  • Pass custom encoding options using the uri_encoding_opts object.
Параметры:
  • string – a string to decode
  • uri_encoding_opts (table) – encoding options (optional, see uri_encoding_opts)
возвращает:

a decoded string
тип возвращаемого значения:
 

строка

Example 1:

This example shows how to decode a string using the default encoding options.

local uri = require('uri')

unescaped_string = uri.unescape('C%2B%2B')
--[[
---
- C++
...
--]]

Example 2:

This example shows how to decode a string using the uri.FORM_URLENCODED encoding options.

local uri = require('uri')

unescaped_string_url_enc = uri.unescape('John+Smith', uri.FORM_URLENCODED)
--[[
---
- John Smith
...
--]]

Example 3:

This example shows how to decode a string using custom encoding options.

local uri = require('uri')

local escape_opts = {
    plus = true,
    unreserved = uri.unreserved("a-z")
}
unescaped_string_custom = uri.unescape('%48ello+%57orld', escape_opts)
--[[
---
- Hello World
...
--]]

Properties

uri.RFC3986

Encoding options that use unreserved symbols defined in RFC 3986. These are default options used to encode and decode using the uri.escape() and uri.unescape() functions, respectively.

See also: uri_encoding_opts

тип возвращаемого значения:
 table
uri.PATH

Options used to encode the path URI component.

See also: uri_encoding_opts

тип возвращаемого значения:
 table
uri.PATH_PART

Options used to encode specific path parts.

See also: uri_encoding_opts

тип возвращаемого значения:
 table
uri.QUERY

Options used to encode the query URI component.

See also: uri_encoding_opts

тип возвращаемого значения:
 table
uri.QUERY_PART

Options used to encode specific query parts.

See also: uri_encoding_opts

тип возвращаемого значения:
 table
uri.FRAGMENT

Options used to encode the fragment URI component.

See also: uri_encoding_opts

тип возвращаемого значения:
 table
uri.FORM_URLENCODED

Options used to encode application/x-www-form-urlencoded form parameters.

See also: uri_encoding_opts

тип возвращаемого значения:
 table

Модуль utf8

Общие сведения

utf8 – это модуль Tarantool для обработки строк в формате UTF-8. Он содержит некоторые функции, которые совместимы с функциями Lua 5.3, но возможности Tarantool намного больше. Например, поскольку Tarantool включает в себя полную копию библиотеки Международных компонентов для Юникода («International Components For Unicode»), доступны также функции сравнения, которые понимают упорядочение символов в кириллице (заглавная буква Ж = строчная буква ж) и японском языке (A в хирагане = A в катакане).

Имя Назначение
casecmp and
cmp		 Сравнения
lower and
upper		 Замена регистра
isalpha,
isdigit,
islower and
isupper		 Определение типа символа
sub Подстроки
len Длина в символах
next Посимвольная итерация
utf8.casecmp(UTF8-string, utf8-string)
Параметры:
  • string (UTF8-string) – строка в формате UTF-8
возвращает:

-1 означает «меньше», 0 означает «равно», +1 означает «больше»
тип возвращаемого значения:
 

число

Сравнение двух строк с Таблицей сортировки символов Юникода по умолчанию (DUCET) для Алгоритма сортировки по Юникоду (Unicode Collation Algorithm). В результате „å“ меньше, чем „B“, хотя значение кодовой точки å (229) больше значения кодовой точки B (66), поскольку алгоритм основывается на значениях Таблица сортировки символов, а не на значениях кодовых точек.

Сравнение осуществляется на основании основного веса. Таким образом, не учитываются элементы, которые влияют на вторичный или последующий вес (такие как «регистр» в латинице или кириллице, или «отличия каны» в японском языке). Если спросить: «Это похоже на сортировку без учета регистра и ударения от компании Майкрософт?» - ответом будет: «Скорее да», хотя Алгоритм сортировки по Юникоду гораздо сложнее, чем это описание.

Пример:

tarantool> utf8.casecmp('é','e'),utf8.casecmp('E','e')
---
- 0
- 0
...
utf8.char(code-point[, code-point ...])
Параметры:
  • number (code-point) – значение кодовой точки в Юникоде, повторяется
возвращает:

строка в UTF-8
тип возвращаемого значения:
 

строка

Число кодовой точки – это значение, которое соответствует символу в Базе данных символов Юникода This is not the same as the byte values of the encoded character, because the UTF-8 encoding scheme is more complex than a simple copy of the code-point number.

Другой способ создать строку с символами Юникода – с помощью механизма экранирования символов \u{шестнадцатеричные-числа}, например, в результате и „\u{41}\u{42}“, и utf8.char(65,66) получим строку „AB“.

Пример:

tarantool> utf8.char(229)
---
- å
...
utf8.cmp(UTF8-string, utf8-string)
Параметры:
  • string (UTF8-string) – строка в формате UTF-8
возвращает:

-1 означает «меньше», 0 означает «равно», +1 означает «больше»
тип возвращаемого значения:
 

число

Сравнение двух строк с Таблицей сортировки символов Юникода по умолчанию (DUCET) для Алгоритма сортировки по Юникоду (Unicode Collation Algorithm). В результате „å“ меньше, чем „B“, хотя значение кодовой точки å (229) больше значения кодовой точки B (66), поскольку алгоритм основывается на значениях Таблица сортировки символов, а не на значениях кода.

Сравнение осуществляется на основании не менее трех значений веса. Таким образом, не учитываются элементы, которые влияют на вторичный или последующий вес (такие как «регистр» в латинице или кириллице, или «отличия каны» в японском языке), а верхний регистр следует за нижним.

Пример:

tarantool> utf8.cmp('é','e'),utf8.cmp('E','e')
---
- 1
- 1
...
utf8.isalpha(UTF8-character)
Параметры:
  • string-or-number (UTF8-character) – отдельный символ UTF8, выраженный в виде однобайтной строки или значения кодовой точки
возвращает:

true (правда) или false (ложь)
тип возвращаемого значения:
 

boolean (логический)

Возврат true (правда), если введенный символ является буквенным, в остальных случаях – false (ложь). В целом, символ считается буквенным, если он используется в рамках слова, а не как число или знак пунктуации. Такой символ необязательно должен быть буквой алфавита.

Пример:

tarantool> utf8.isalpha('Ж'),utf8.isalpha('å'),utf8.isalpha('9')
---
- true
- true
- false
...
utf8.isdigit(UTF8-character)
Параметры:
  • string-or-number (UTF8-character) – отдельный символ UTF8, выраженный в виде однобайтной строки или значения кодовой точки
возвращает:

true (правда) или false (ложь)
тип возвращаемого значения:
 

boolean (логический)

Возврат true (правда), если введенный символ является цифрой, в остальных случаях – false (ложь).

Пример:

tarantool> utf8.isdigit('Ж'),utf8.isdigit('å'),utf8.isdigit('9')
---
- false
- false
- true
...
utf8.islower(UTF8-character)
Параметры:
  • string-or-number (UTF8-character) – отдельный символ UTF8, выраженный в виде однобайтной строки или значения кодовой точки
возвращает:

true (правда) или false (ложь)
тип возвращаемого значения:
 

boolean (логический)

Возврат true (правда), если введенный символ относится к нижнему регистру, в остальных случаях – false (ложь).

Пример:

tarantool> utf8.islower('Ж'),utf8.islower('å'),utf8.islower('9')
---
- false
- true
- false
...
utf8.isupper(UTF8-character)
Параметры:
  • string-or-number (UTF8-character) – отдельный символ UTF8, выраженный в виде однобайтной строки или значения кодовой точки
возвращает:

true (правда) или false (ложь)
тип возвращаемого значения:
 

boolean (логический)

Возврат true (правда), если введенный символ относится к верхнему регистру, в остальных случаях – false (ложь).

Пример:

tarantool> utf8.isupper('Ж'),utf8.isupper('å'),utf8.isupper('9')
---
- true
- false
- false
...
utf8.len(UTF8-string[, start-byte[, end-byte]])
Параметры:
  • string (UTF8-string) – строка в формате UTF-8
  • integer (end-byte) – позиция байта первого символа
  • integer – позиция байта для остановки
возвращает:

количество символов в строке или же от начала до конца
тип возвращаемого значения:
 

число

Позиции байта в начале и в конце могут быть отрицательными, что указывает на отсчет с конца строки, а не с начала.

Если строка содержит последовательность байтов, которая неприменима для UTF-8, каждый байт в неправильной последовательности будет считаться за один символ.

UTF-8 представляет собой схему кодирования изменяемого размера. Как правило, одна буква латиницы занимает один байт, буква кириллицы занимает два байта, а символ из китайского или японского языка занимает три байта, максимальный размер – четыре байта.

Пример:

tarantool> utf8.len('G'),utf8.len('ж')
---
- 1
- 1
...

tarantool> string.len('G'),string.len('ж')
---
- 1
- 2
...
utf8.lower(UTF8-string)
Параметры:
  • string (UTF8-string) – строка в формате UTF-8
возвращает:

та же строка в нижнем регистре
тип возвращаемого значения:
 

строка

Пример:

tarantool> utf8.lower('ÅΓÞЖABCDEFG')
---
- åγþжabcdefg
...
utf8.next(UTF8-string[, start-byte])
Параметры:
  • string (UTF8-string) – строка в формате UTF-8
  • integer (start-byte) – позиция байта внутри строки, с которой начать выполнение, по умолчанию = 1
возвращает:

позиция байта следующего символа и значение кодовой точки следующего символа
тип возвращаемого значения:
 

таблица

Функция next часто используется в цикле для получения символа за раз из строки в формате UTF-8.

Пример:

В строке „åa“ первый символ – „å“, он начинается в позиции 1, занимает два байта, поэтому символ после него будет на позиции 3, значение кодовой точки в Юникоде (десятичное) – 229.

tarantool> -- показать позицию следующего символа + кодовую точку первого символа
tarantool> utf8.next('åa', 1)
---
- 3
- 229
...
tarantool> -- (цикл) показать кодовую точку каждого символа
tarantool> for position,codepoint in utf8.next,'åa' do print(codepoint) end
229
97
...
utf8.sub(UTF8-string, start-character[, end-character])
Параметры:
  • string (UTF8-string) – строка в формате UTF-8
  • number (end-character) – позиция первого символа
  • number – позиция последнего символа
возвращает:

строка в формате UTF-8, «подстрока» введенного значения
тип возвращаемого значения:
 

строка

Позиции символа в начале и в конце могут быть отрицательными, что указывает на отсчет с конца строки, а не с начала.

Значение end-character по умолчанию – длина введенной строки. Таким образом, выполнение utf8.sub(1, 'abc') вернет „abc“, т.е. введенную строку.

Пример:

tarantool> utf8.sub('åγþжabcdefg', 5, 8)
---
- abcd
...
utf8.upper(UTF8-string)
Параметры:
  • string (UTF8-string) – строка в формате UTF-8
возвращает:

та же строка в верхнем регистре
тип возвращаемого значения:
 

строка

Примечание

В редких случаях результат в верхнем регистре может быть длиннее введенной строки в нижнем регистре, например, utf8.upper('ß') вернет „SS“.

Пример:

tarantool> utf8.upper('åγþжabcdefg')
---
- ÅΓÞЖABCDEFG
...

Модуль uuid

Общие сведения

UUID означает универсальный уникальный идентификатор. Если приложение требует, чтобы значение было уникальным в рамках одной машины или одной БД, лучше использовать простой счетчик, а не UUID. Это связано с тем, что получать UUID-значения времязатратно и требует системного вызова. Используйте UUID для кластеров машин и крупных распределенных приложений. Tarantool генерирует UUID-значения по варианту 1 версии 4 правил, определенных в RFC 4122.

Справочник по API

Ниже приведен перечень всех функций и элементов модуля uuid.

Имя Назначение
uuid.NULL Объект c нулевым UUID
uuid()
uuid.bin()
uuid.str()		 Получение UUID
uuid.new() Создание UUID
uuid.fromstr()
uuid.frombin()
uuid_object:bin()
uuid_object:str()		 Получение конвертированного UUID
uuid.is_uuid() Проверка, является ли указанное значение UUID
uuid_object:isnil() Проверка, состоит ли UUID из одних нулей
uuid.NULL

A nil UUID object. Contains the all-zero UUID value – 00000000-0000-0000-0000-000000000000.

uuid.new()

Since version 2.4.1. Create a UUID sequence. You can use it in an index over a UUID field. For example, to create such index for a space named test, say:

tarantool> box.space.test:create_index("pk", {parts={{field = 1, type = 'uuid'}}})

Теперь можно вставить UUID’ы в спейс:

tarantool> box.space.test:insert{uuid.new()}
---
- [e631fdcc-0e8a-4d2f-83fd-b0ce6762b13f]
...

tarantool> box.space.test:insert{uuid.fromstr('64d22e4d-ac92-4a23-899a-e59f34af5479')}
---
- [64d22e4d-ac92-4a23-899a-e59f34af5479]
...

tarantool> box.space.test:select{}
---
- - [64d22e4d-ac92-4a23-899a-e59f34af5479]
- [e631fdcc-0e8a-4d2f-83fd-b0ce6762b13f]
...
возвращает:UUID
тип возвращаемого значения:
 cdata.
uuid.__call()
возвращает:UUID
тип возвращаемого значения:
 cdata.
uuid.bin([byte-order])
Параметры:
  • byte-order (string) –

    Byte order of the resulting UUID:

    • 'l' – little-endian
    • 'b' – big-endian
    • 'h', 'host' – endianness depends on host (default)
    • 'n', 'network' – endianness depends on network
возвращает:

UUID
тип возвращаемого значения:
 

16-байтная строка
uuid.str()
возвращает:UUID
тип возвращаемого значения:
 36-байтная двоичная строка
uuid.fromstr(uuid-str)
Параметры:
  • uuid-str (string) – UUID в 36-байтной шестнадцатеричной строке
возвращает:

конвертированный UUID
тип возвращаемого значения:
 

cdata.
uuid.frombin(uuid-bin[, byte-order])
Параметры:
  • uuid-bin (string) – UUID в 16-байтной двоичной строке
  • byte-order (string) –

    Byte order of the given string:

    • 'l' – little-endian,
    • 'b' – big-endian,
    • 'h', 'host' – endianness depends on host (default),
    • 'n', 'network' – endianness depends on network.
возвращает:

конвертированный UUID
тип возвращаемого значения:
 

cdata.
uuid.is_uuid(value)

Since version 2.6.1.

Параметры:
  • value – проверяемое значение
возвращает:

true, если указанное значение имеет тип UUID, в противном случае false
тип возвращаемого значения:
 

bool (логический)
object uuid_object
uuid_object:bin([byte-order])
Параметры:
  • byte-order (string) –

    Byte order of the resulting UUID:

    • 'l' – little-endian,
    • 'b' – big-endian,
    • 'h', 'host' – endianness depends on host (default),
    • 'n', 'network' – endianness depends on network.
возвращает:

UUID, сконвертированный из введенного значения формата cdata.
тип возвращаемого значения:
 

16-байтная двоичная строка
uuid_object:str()
возвращает:UUID, сконвертированный из введенного значения формата cdata.
тип возвращаемого значения:
 36-байтная шестнадцатеричная строка
uuid_object:isnil()

Значение UUID из одних нулей может быть выражено как uuid.NULL или uuid.fromstr('00000000-0000-0000-0000-000000000000'). Сравнение со значением из одних нулей также может быть выражено как uuid_with_type_cdata == uuid.NULL.

возвращает:true (правда), если значение состоит из одних нулей, в противном случае false (ложь).
тип возвращаемого значения:
 bool (логический)

Пример

tarantool> uuid = require('uuid')
---
...
tarantool> uuid(), uuid.bin(), uuid.str()
---
- 16ffedc8-cbae-4f93-a05e-349f3ab70baa
- !!binary FvG+Vy1MfUC6kIyeM81DYw==
- 67c999d2-5dce-4e58-be16-ac1bcb93160f
...
tarantool> uu = uuid()
---
...
tarantool> #uu:bin(), #uu:str(), type(uu), uu:isnil()
---
- 16
- 36
- cdata
- false
...

Module varbinary

Since: 3.0.0

Overview

The varbinary module provides functions for operating variable-length binary objects in Lua. It provides functions for creating varbinary objects, checking their type, and also defines basic operators on such objects.

For example:

local varbinary = require('varbinary')

-- Create a varbinary object
local bin = varbinary.new('data')
local bin_hex = varbinary.new('\xFF\xFE')

-- Check whether a value is a varbinary object
varbinary.is(bin) -- true
varbinary.is(bin_hex) -- true
varbinary.is(100) -- false
varbinary.is('data') -- false

-- Check varbinary objects equality
print(bin == varbinary.new('data')) -- true
print(bin == 'data') -- true
print(bin ~= 'data1') -- true
print(bin_hex ~= '\xFF\xFE') -- false

-- Check varbinary objects length
print(#bin) -- 4
print(#bin_hex) -- 2

-- Print string representation
print(tostring(bin)) -- data

Encoding varbinary objects

varbinary objects preserve their binary type when encoded by the built-in MsgPack and YAML encoders. See the difference with strings:

  • String to MsgPack:

    tarantool> msgpack.encode('\xFF\xFE')
---
- "\xA2\xFF\xFE"
...

  • varbinary to MsgPack:

    tarantool> msgpack.encode(varbinary.new('\xFF\xFE'))
---
- "\xC4\x02\xFF\xFE"
...

  • String to YAML:

    tarantool> '\xFF\xFE'
---
- "\xFF\xFE"
...

  • varbinary to YAML:

    tarantool> varbinary.new('\xFF\xFE')
---
- !!binary //4=
...

Примечание

The JSON format doesn’t support the binary type so varbinary objects are encoded as plain strings in JSON:

tarantool> json.encode('\xFF\xFE')
---
- "\"\xFF\xFE\""
...

tarantool> json.encode(varbinary.new('\xFF\xFE'))
---
- "\"\xFF\xFE\""
...

Decoding binary data to varbinary objects

The built-in decoders also decode binary data fields (fields with the binary tag in YAML and the MP_BIN type in MsgPack) to varbinary objects by default:

tarantool> varbinary.is(msgpack.decode('\xC4\x02\xFF\xFE'))
---
- true
...

tarantool> varbinary.is(yaml.decode('!!binary //4='))
---
- true
...

Важно

This behavior is different from what it was before Tarantool 3.0. In earlier versions, such fields were decoded to plain strings. To return to this behavior, use the compat option binary_data_decoding.

API Reference

Below is a list of varbinary functions, properties, and related objects.

Functions  
varbinary.is() Check that the argument is a varbinary object
varbinary.new() Create a varbinary object
Metamethods  
varbinary_object.__eq Checks the equality of two varbinary objects
varbinary_object.__len Returns the length of the binary data in bytes
varbinary_object.__tostring Returns the binary data in a plain string

Functions

varbinary.is(object)

Check that the given object is a varbinary object.

Параметры:
  • object (object) – an object to check
Return:

Whether the given object is of varbinary type
Rtype:

boolean

Example:

local bin = varbinary.new('data')
local bin_hex = varbinary.new('\xFF\xFE')

-- Check whether a value is a varbinary object
varbinary.is(bin) -- true
varbinary.is(bin_hex) -- true
varbinary.is(100) -- false
varbinary.is('data') -- false
varbinary.new(string)

Create a new varbinary object from a given string.

Параметры:
  • string (string) – a string object
Return:

A varbinary object containing the string data
Rtype:

cdata

Example:

local bin = varbinary.new('data')
local bin_hex = varbinary.new('\xFF\xFE')
varbinary.new(ptr, size)

Create a new varbinary object from a cdata pointer and size.

Параметры:
  • ptr (cdata) – a cdata pointer
  • size (number) – object size in bytes
Return:

A varbinary object containing the data
Rtype:

cdata

Example:

local bin2 = varbinary.new(ffi.cast('const char *', 'data'), 4)
varbinary.is(bin2) -- true
print(bin2) -- data

Metamethods

object varbinary_object
varbinary_object:__eq(object)

Checks the equality of two varbinary objects or a varbinary object and a string. A varbinary object equals to another varbinary object or a string if it contains the same data.

Defines the == and ~= operators for varbinary objects.

Rtype:boolean

Example:

print(bin == varbinary.new('data')) -- true
print(bin == 'data') -- true
print(bin ~= 'data1') -- true
print(bin_hex ~= '\xFF\xFE') -- false
varbinary_object:__len()

Returns the length of the binary data in bytes.

Defines the # operator for varbinary objects.

Rtype:number

Example:

print(#bin) -- 4
print(#bin_hex) -- 2
varbinary_object:__tostring()

Returns the binary data in a plain string.

Defines the tostring() function for varbinary objects.

Rtype:string

Модуль xlog

Модуль xlog включает в себя одну функцию: pairs(). Ее можно использовать для чтения файлов снимка или файлов журнала упреждающей записи (WAL) в Tarantool. Описание формата файла дается в разделе Персистентность данных и формат WAL-файла.

xlog.pairs([file-name])

Открытие файла и итерация по одной записи файла за раз.

возвращает:итератор, который можно использовать в цикле for / end.
тип возвращаемого значения:
 итератор

Возможные ошибки: Файл не содержит снимок в правильном формате или информацию журнала упреждающей записи.

Пример:

В данном примере производится чтение первого WAL-файла, который был создан в директории wal_dir в рамках наших упражнений в «Руководстве для начинающих».

Каждый результат из pairs() выводится в формате MsgPack, поэтому его структуру можно указать с помощью __serialize.

xlog = require('xlog')
t = {}
for k, v in xlog.pairs('00000000000000000000.xlog') do
  table.insert(t, setmetatable(v, { __serialize = "map"}))
end
return t

Первые строки результата будут выглядеть следующим образом:

(...)
---
- - {'BODY':   {'space_id': 272, 'index_base': 1, 'key': ['max_id'],
                'tuple': [['+', 2, 1]]},
     'HEADER': {'type': 'UPDATE', 'timestamp': 1477846870.8541,
                'lsn': 1, 'server_id': 1}}
  - {'BODY':   {'space_id': 280,
                 'tuple': [512, 1, 'tester', 'memtx', 0, {}, []]},
     'HEADER': {'type': 'INSERT', 'timestamp': 1477846870.8597,
                'lsn': 2, 'server_id': 1}}

Модуль yaml

Общие сведения

The yaml module takes strings in YAML format and decodes them, or takes a series of non-YAML values and encodes them.

Указатель

Ниже приведен перечень всех функций и элементов модуля yaml.

Имя Назначение
yaml.encode() Конвертация Lua-объекта в YAML-строку
yaml.decode() Конвертация YAML-строки в Lua-объект
__serialize parameter Output structure specification
yaml.cfg() Изменение конфигурации
yaml.NULL Аналог «nil» в языке Lua
yaml.encode(lua_value)

Конвертация Lua-объекта в YAML-строку.

Параметры:
  • lua_value – скалярное значение или значение из Lua-таблицы.
возвращает:

оригинальное значение, преобразованное в YAML-строку.
тип возвращаемого значения:
 

строка
yaml.decode(string)

Конвертация YAML-строки в Lua-объект.

Параметры:
  • string – строка в формате YAML.
возвращает:

оригинальное содержание в формате Lua-таблицы.
тип возвращаемого значения:
 

таблица

__serialize parameter:

The YAML output structure can be specified with __serialize:

'seq' or 'map' also enable the flow (compact) mode for the YAML serializer (flow="[1,2,3]" vs block=" - 1\n - 2\n - 3\n").

Serializing 'A' and 'B' with different __serialize values brings different results:

tarantool> yaml.encode(setmetatable({'A', 'B'}, { __serialize="seq"}))
---
- '["A","B"]'
...
tarantool> yaml.encode(setmetatable({'A', 'B'}, { __serialize="map"}))
---
- '{"1":"A","2":"B"}'
...
tarantool> yaml.encode({setmetatable({f1 = 'A', f2 = 'B'}, { __serialize="map"})})
---
- '[{"f2":"B","f1":"A"}]'
...
tarantool> yaml.encode({setmetatable({f1 = 'A', f2 = 'B'}, { __serialize="seq"})})
---
- '[[]]'
...
yaml.cfg(table)

Set values affecting the behavior of encode and decode functions.

The values are all either integers or boolean true/false.

Характеристика Значение по умолчанию Назначение
cfg.encode_invalid_numbers true A flag saying whether to enable encoding of NaN and Inf numbers
cfg.encode_number_precision 14 Precision of floating point numbers
cfg.encode_load_metatables true A flag saying whether the serializer will follow __serialize metatable field
cfg.encode_use_tostring false A flag saying whether to use tostring() for unknown types
cfg.encode_invalid_as_nil false A flag saying whether to use NULL for non-recognized types
cfg.encode_sparse_convert true A flag saying whether to handle excessively sparse arrays as maps. See detailed description below
cfg.encode_sparse_ratio 2 1/encode_sparse_ratio is the permissible percentage of missing values in a sparse array
cfg.encode_sparse_safe 10 A limit ensuring that small Lua arrays are always encoded as sparse arrays (instead of generating an error or encoding as map)
cfg.decode_invalid_numbers true A flag saying whether to enable decoding of NaN and Inf numbers
cfg.decode_save_metatables true A flag saying whether to set metatables for all arrays and maps

Sparse arrays features:

During encoding, The YAML encoder tries to classify table into one of four kinds:

An array is excessively sparse when all the following conditions are met:

The YAML encoder will never consider an array to be excessively sparse when encode_sparse_ratio = 0. The encode_sparse_safe limit ensures that small Lua arrays are always encoded as sparse arrays. By default, attempting to encode an excessively sparse array will generate an error. If encode_sparse_convert is set to true, excessively sparse arrays will be handled as maps.

yaml.cfg() example 1:

The following code will encode 0/0 as NaN («not a number») and 1/0 as Inf («infinity»), rather than returning nil or an error message:

yaml = require('yaml')
yaml.cfg{encode_invalid_numbers = true}
x = 0/0
y = 1/0
yaml.encode({1, x, y, 2})

Результат запроса yaml.encode() будет следующим:

tarantool> yaml.encode({1, x, y, 2})
---
- '[1,nan,inf,2]
...

yaml.cfg example 2:

To avoid generating errors on attempts to encode unknown data types as userdata/cdata, you can use this code:

tarantool> httpc = require('http.client').new()
---
...

tarantool> yaml.encode(httpc.curl)
---
- error: unsupported Lua type 'userdata'
...

tarantool> yaml.encode(httpc.curl, {encode_use_tostring=true})
---
- '"userdata: 0x010a4ef2a0"'
...

Примечание

To achieve the same effect for only one call to yaml.encode() (i.e. without changing the configuration permanently), you can use yaml.encode({1, x, y, 2}, {encode_invalid_numbers = true}).

Similar configuration settings exist for JSON and MsgPack.

yaml.NULL

Значение, сопоставимое с нулевым значением «nil» в языке Lua, которое можно использовать в качестве объекта-заполнителя в кортеже.

Пример

tarantool> yaml = require('yaml')
---
...
tarantool> y = yaml.encode({'a', 1, 'b', 2})
---
...
tarantool> z = yaml.decode(y)
---
...
tarantool> z[1], z[2], z[3], z[4]
---
- a
- 1
- b
- 2
...
tarantool> if yaml.NULL == nil then print('hi') end
hi
---
...

Набор YAML-стилей можно указать с помощью __serialize:

Serializing 'A' and 'B' with different __serialize values causes different results:

tarantool> yaml = require('yaml')
---
...

tarantool> print(yaml.encode(setmetatable({'A', 'B'}, { __serialize="sequence"})))
---
- A
- B
...

---
...

tarantool> print(yaml.encode(setmetatable({'A', 'B'}, { __serialize="seq"})))
--- ['A', 'B']
...

---
...

tarantool> print(yaml.encode({setmetatable({f1 = 'A', f2 = 'B'}, { __serialize="map"})}))
---
- {'f2': 'B', 'f1': 'A'}
...

---
...

Прочие компоненты пакета

All the Tarantool modules are, at some level, inside a package which, appropriately, is named package. There are also miscellaneous functions and variables which are outside all modules.

Имя Назначение
tonumber64() Конвертация строки или Lua-числа в 64-битное целое число
dostring() Анализ и выполнение произвольного Lua-кода
package.path Get file paths used to search for Lua modules
package.cpath Get file paths used to search for C modules
package.loaded Show Lua or C modules loaded by Tarantool
package.searchroot Get the root path for a directory search
package.setsearchroot Set the root path for a directory search
tonumber64(value)

Конвертация строки или Lua-числа в 64-битное целое число. Входное значение может быть выражено десятичным, двоичным (например, 0b1010) или шестнадцатеричным (например, -0xffff) числом. Результат может использоваться в арифметике, причем скорее в 64-битной целочисленной арифметике, а не в арифметике в системе с плавающей запятой. (Операции с неконвертированными Lua-числами выполняются в арифметике в системе с плавающей запятой.) Функция tonumber64() в Tarantool является глобальной.

Пример:

tarantool> type(123456789012345), type(tonumber64(123456789012345))
---
- number
- number
...
tarantool> i = tonumber64('1000000000')
---
...
tarantool> type(i), i / 2, i - 2, i * 2, i + 2, i % 2, i ^ 2
---
- number
- 500000000
- 999999998
- 2000000000
- 1000000002
- 0
- 1000000000000000000
...

Warning: There is an underlying LuaJIT library that operates with C rules. Therefore you should expect odd results if you compare unsigned and signed (for example 0ULL > -1LL is false), or if you use numbers outside the 64-bit integer range (for example 9223372036854775808LL is negative). Also you should be aware that type(number-literal-ending-in-ULL) is cdata, not a Lua arithmetic type, which prevents direct use with some functions in Lua libraries such as math. See the LuaJIT reference and look for the phrase «64 bit integer arithmetic». and the phrase «64 bit integer comparison». Or see the comments on Issue#4089.

dostring(lua-chunk-string[, lua-chunk-string-argument ...])

Анализ и выполнение произвольного Lua-кода. Данная функция используется преимущественно для определения и выполнения Lua-кода без необходимости внесения изменений в глобальное Lua-окружение.

Параметры:
  • lua-chunk-string (string) – Lua-код
  • lua-chunk-string-argument (lua-value) – ноль или другие скалярные значения, которые заменяются или к которым прибавляются значения.
возвращает:

то, что возвращает Lua-код.

Возможные ошибки: Ошибка компиляции появляется как Lua-ошибка.

Пример:

tarantool> dostring('abc')
---
error: '[string "abc"]:1: ''='' expected near ''<eof>'''
...
tarantool> dostring('return 1')
---
- 1
...
tarantool> dostring('return ...', 'hello', 'world')
---
- hello
- world
...
tarantool> dostring([[
         >   local f = function(key)
         >     local t = box.space.tester:select{key}
         >     if t ~= nil then
         >       return t[1]
         >     else
         >       return nil
         >     end
         >   end
         >   return f(...)]], 1)
---
- null
...
package.path

Get file paths used to search for Lua modules. For example, these paths are used to find modules loaded using the require() directive.

See also: package.searchroot()

package.cpath

Get file paths used to search for C modules. For example, these paths are used to find modules loaded using the require() directive.

See also: package.searchroot()

package.loaded

Show Lua or C modules loaded by Tarantool, so that their functions and members are available. loaded shows both pre-loaded modules and modules added using the require() directive.

See also: package.searchroot()

package.searchroot()

Return the current search root, which defines the path to the root directory from which dependencies are loaded. By default, the search root is the current directory.

Примечание

The current directory is obtained using debug.sourcedir().

Example

Suppose the application has the following structure:

/home/testuser/myapp
├── .rocks/share/tarantool/
│   └── foo.lua
├── init.lua
└── modules
    └── bar.lua

In this case, modules are placed in the same directory as the application initialization file. If you run the application using the tarantool command from the myapp directory, …

/home/testuser/myapp$ tarantool init.lua

… the search root is /home/testuser/myapp and Tarantool finds all modules in this directory automatically. This means that to load the foo and modules.bar modules in init.lua, you only need to add the corresponding require directives:

-- init.lua --
require('foo')
require('modules.bar')

Starting with 2.11.0, you can also run the application using the tarantool command from the directory other than myapp:

/home/testuser$ tarantool myapp/init.lua

In this case, the path to the initialization file (/home/testuser/myapp) is added to search paths for modules.

To load modules placed outside of the path to the application directory, use package.setsearchroot().

package.setsearchroot([search-root])

Set the search root, which defines the path to the root directory from which dependencies are loaded. By default, the search root is the current directory (see package.searchroot()).

Параметры:
  • search-root (string) – a relative or absolute path to the search root. If search-root is a relative path, it is expanded to an absolute path. You can omit this argument or set it to box.NULL to reset the search root to the current directory.

Example

Suppose external modules are stored outside the application directory, for example:

/home/testuser/
├── myapp
│   └── init.lua
└── mymodules
    ├── .rocks/share/tarantool/
    │   └── foo.lua
    └── modules
        └── bar.lua

In this case, you can specify the /home/testuser/mymodules path as the search root for modules in the following way:

-- init.lua --
package.setsearchroot('/home/testuser/mymodules')

Then, you can load the foo and bar modules using the require() directive:

-- init.lua --
require('foo')
require('modules.bar')

Коды ошибок базы данных

The table below lists some popular errors that can be raised by Tarantool in case of various issues. You can find a complete list of errors in the errcode.h file.

Примечание

The box.error module provides the ability to get the information about the last error raised by Tarantool or raise custom errors manually.

Code box.error value Description
ER_NONMASTER box.error.NONMASTER (Репликация) Экземпляр сервера не может вносить изменения в данные, если он не является мастером.
ER_ILLEGAL_PARAMS box.error.ILLEGAL_PARAMS Недопустимые параметры. Некорректное протокольное сообщение.
ER_MEMORY_ISSUE box.error.MEMORY_ISSUE Нехватка оперативной памяти: достижение предела памяти memtx_memory.
ER_WAL_IO box.error.WAL_IO Failed to write to disk. May mean: failed to record a change in the write-ahead log.
ER_READONLY box.error.READONLY Can’t modify data on a read-only instance.
ER_KEY_PART_COUNT box.error.KEY_PART_COUNT Key part count is not the same as index part count.
ER_NO_SUCH_SPACE box.error.NO_SUCH_SPACE Указанный спейс отсутствует.
ER_NO_SUCH_INDEX box.error.NO_SUCH_INDEX Указанного индекса нет в указанном спейсе.
ER_PROC_LUA box.error.PROC_LUA Возникла ошибке в Lua-процедуре.
ER_FIBER_STACK box.error.FIBER_STACK При создании нового файбера был достигнут предел рекурсии. Обычно это указывает на то, что хранимая процедура слишком часто рекурсивно вызывает себя.
ER_UPDATE_FIELD box.error.UPDATE_FIELD Возникла ошибка во время обновления поля.
ER_TUPLE_FOUND box.error.TUPLE_FOUND В уникальном индексе есть повторяющийся ключ.

Обработка ошибок

Ниже представлены несколько процедур для более надежного вызова Lua-функций в случае ошибок, в частности, ошибок базы данных.

  1. Invoke a function using pcall.

    Take advantage of Lua’s mechanisms for Error handling and exceptions, particularly pcall. That is, instead of invoking with …

    box.space.{space-name}:{function-name}()

    … call the function as follows:

    if pcall(box.space.{space-name}.{function-name}, box.space.{space-name}) ...

    For some Tarantool box functions, pcall also returns error details, including a file-name and line-number within Tarantool’s source code. This can be seen by unpacking, for example:

    status, error = pcall(function() box.schema.space.create('') end)
error:unpack()

    See the tutorial Sum a JSON field for all tuples to see how pcall can fit in an application.

  2. Examine errors and raise new errors using box.error.

    To make a new error and pass it on, the box.error module provides box.error().

    To find the last error, the box.error submodule provides box.error.last(). There is also a way to find the text of the last operating-system error for certain functions – errno.strerror([code]).

  3. Запись в журнал.

    Записывайте сообщения в журнал с помощью модуля log.

    Filter automatically generated messages using the log configuration parameter.

Generally, for Tarantool built-in functions which are designed to return objects: the result is an object, or nil, or a Lua error. For example consider the fio_read.lua program in a cookbook:

#!/usr/bin/env tarantool

local fio = require('fio')
local errno = require('errno')
local f = fio.open('/tmp/xxxx.txt', {'O_RDONLY' })
if not f then
    error("Failed to open file: "..errno.strerror())
end
local data = f:read(4096)
f:close()
print(data)

After a function call that might fail, like fio.open() above, it is common to see syntax like if not f then ... or if f == nil then ..., which check for common failures. But if there had been a syntax error, for example fio.opex instead of fio.open, then there would have been a Lua error and f would not have been changed. If checking for such an obvious error had been a concern, the programmer would probably have used pcall().

Все функции в модулях Tarantool должны работать таким образом, если в руководстве явно не говорится об обратном.

Средства отладки

Общие сведения

Пользователи Tarantool могут воспользоваться преимуществами встроенных средств отладки, которые составляют часть:

Библиотека debug предоставляет интерфейс для отладки Lua-программ. Все функции этой библиотеки содержатся в таблице debug. В функциях для работы с потоками есть дополнительный первый параметр, в котором указывается необходимый поток. По умолчанию, это всегда текущий поток.

Примечание

Библиотеку следует использовать только для отладки и профилирования, а не в качестве программного средства, поскольку данные функции выполняются слишком долго. Кроме того, некоторые из этих функций могут привести к нарушению работы безопасного в других отношениях кода.

Указатель

Ниже приведен перечень всех функций библиотеки debug.

Имя Назначение
debug.debug() Вход в интерактивный режим
debug.getfenv() Получение среды объекта
debug.gethook() Получение текущих настроек ловушки потока
debug.getinfo() Получение информации о функции
debug.getlocal() Получение имени и значения локальной переменной
debug.getmetatable() Получение метатаблицы объекта
debug.getregistry() Получение таблицы реестра
debug.getupvalue() Получение имени и значения сопоставляющего значения
debug.setfenv() Определение среды объекта
debug.sethook() Определение данной функции в качестве ловушки
debug.setlocal() Присваивание значения локальной переменной
debug.setmetatable() Определение метатаблицы объекта
debug.setupvalue() Присваивание значения сопоставляющему значению
debug.sourcedir() Get the source directory name
debug.sourcefile() Get the source file name
debug.traceback() Получение обратной трассировки стека вызовов
debug.debug()

Вход в интерактивный режим и выполнение каждой строки, которую печатает пользователь. Пользователь может, в частности, проверять глобальные и локальные переменные, изменять их значения и вычислять выражения.

Введите cont для выхода из данной функции, чтобы вызывающий клиент мог продолжить выполнение.

Примечание

Команды для debug.debug() не вложены лексически в какую-либо функцию, поэтому у них нет прямого доступа к локальным переменным.

debug.getfenv(object)
Параметры:
  • object – объект, для которого будет получена среда
возвращает:

среда объекта object
debug.gethook([thread])
возвращает:

текущие настройки ловушки потока thread в виде трех значений:

  • текущая функция-ловушка
  • текущая маска ловушки
  • текущий счетчик ловушки, как определяет функция debug.sethook()
debug.getinfo([thread, ]function[, what])
Параметры:
  • function – функция, по которой будет получена информация
  • what (string) – какую информацию о функции function вернуть
возвращает:

таблица с информацией о функции function

Можно передать функцию function напрямую или же передать число, которое указывает на функцию, выполняемую на уровне function стека вызовов данного потока thread: уровень 0 – это текущая функция (сама функция getinfo()), уровень 1 – это функция, которая вызвала getinfo(), и т.д. Если для функции function указано число больше числа активных функций, getinfo() вернет nil.

По умолчанию, what – это вся доступная информация, кроме таблицы допустимых строк. Если задать опцию f, добавится поле под названием func с самой функцией. Если задать опцию L, добавится поле под названием activelines с таблицей доступных строк.

debug.getlocal([thread, ]level, local)
Параметры:
  • level (number) – уровень стека
  • local (number) – индекс локальной переменной
возвращает:

имя и значение локальной переменной с индексом local функции на уровне level стека или nil, если нет локальной переменной с указанным индексом; появится ошибка, если уровень level вне диапазона

Примечание

Можно вызвать debug.getinfo() для проверки доступности уровня.

debug.getmetatable(object)
Параметры:
  • object – объект, для которого будет получена метатаблица
возвращает:

метатаблица объекта object или nil, если метатаблица отсутствует
debug.getregistry()
возвращает:таблица реестра
debug.getupvalue(func, up)
Параметры:
  • func (function) – функция, для которой будет получено сопоставляющее значение
  • up (number) – индекс сопоставляющего значения функции
возвращает:

имя и значение сопоставляющего значения с индексом up функции func или nil, если нет сопоставляющего значения в пределах заданного индекса
debug.setfenv(object, table)

Определение среды объекта object для таблицы table.

Параметры:
  • object – объект, среда которого будет изменена
  • table (table) – таблица для определения среды объекта
возвращает:

объект object
debug.sethook([thread, ]hook, mask[, count])

Определение данной функции в качестве ловушки. При вызове без аргументов ловушка отключается.

Параметры:
  • hook (function) – функция, которая будет определена в качестве ловушки
  • mask (string) – описание того, когда будет вызвана ловушка hook; может принимать следующие значения: * c – ловушка``hook`` вызывается каждый раз, когда Lua вызывает функцию * r – ловушка hook вызывается каждый раз, когда Lua возвращается из функции * l – ловушка hook вызывается каждый раз, когда Lua переходит на новую строку кода
  • count (number) – описание того, когда будет вызвана ловушка hook; если отличается от нуля, ловушка hook вызывается после каждой инструкции count.
debug.setlocal([thread, ]level, local, value)

Присвоение значения value локальной переменной с индексом local функции на уровне level стека

Параметры:
  • level (number) – уровень стека
  • local (number) – индекс локальной переменной
  • value – значение, присваиваемое локальной переменной
возвращает:

имя локальной переменной или nil, если локальная переменная с заданным индексом отсутствует; возникает ошибка, если уровень level вне диапазона

Примечание

Можно вызвать debug.getinfo() для проверки доступности уровня.

debug.setmetatable(object, table)

Определение метатаблицы объекта object для таблицы table.

Параметры:
  • object – объект, метатаблица которого будет изменена
  • table (table) – таблица для определения метатаблицы объекта
debug.setupvalue(func, up, value)

Присвоение значения value сопоставляющему значению с индексом up функции func.

Параметры:
  • func (function) – функция, для которой будет определено сопоставляющее значение
  • up (number) – индекс сопоставляющего значения функции
  • value – значение, присваиваемое сопоставляющему значению функции
возвращает:

имя сопоставляющего значения или nil, если сопоставляющее значение с данным индексом отсутствует
debug.sourcedir([level])
Параметры:
  • level (number) – the level of the call stack which should contain the path (default is 2)
возвращает:

a string with the relative path to the source file directory

Instead of debug.sourcedir() one can say debug.__dir__ which means the same thing.

Determining the real path to a directory is only possible if the function was defined in a Lua file (this restriction may not apply for loadstring() since Lua will store the entire string in debug info).

If debug.sourcedir() is part of a return argument, then it should be inside parentheses: return (debug.sourcedir()).

debug.sourcefile([level])
Параметры:
  • level (number) – the level of the call stack which should contain the path (default is 2)
возвращает:

a string with the relative path to the source file

Instead of debug.sourcefile() one can say debug.__file__ which means the same thing.

Determining the real path to a file is only possible if the function was defined in a Lua file (this restriction may not apply to loadstring() since Lua will store the entire string in debug info).

If debug.sourcefile() is part of a return argument, then it should be inside parentheses: return (debug.sourcefile()).

debug.traceback([thread, ][message][, level])
Параметры:
  • message (string) – необязательное сообщение, добавленное к началу обратной трассировки
  • level (number) – указывает на каком уровне начинать обратную трассировку (по умолчанию, 1)
возвращает:

строка с обратной трассировкой стека вызовов

Debug example:

Make a file in the /tmp directory named example.lua, containing:

function w()
  print(debug.sourcedir())
  print(debug.sourcefile())
  print(debug.traceback())
  print(debug.getinfo(1)['currentline'])
end
w()

Execute tarantool /tmp/example.lua. Expect to see this:

/tmp
/tmp/example.lua
stack traceback:
    /tmp/example.lua:4: in function 'w'
    /tmp/example.lua:7: in main chunk
5

JSON-пути

Общие сведения

Since version 2.3, Tarantool supports JSON path updates. You can update or upsert formatted tuple / space / index fields by name (not only by field number). Updates of nested structures are also supported.

Пример:

tarantool> box.cfg{};
         > format = {};
         > format[1] = {'field1', 'unsigned'};
         > format[2] = {'field2', 'map'};
         > format[3] = {'field3', 'array'};
         > format[4] = {'field4', 'string', is_nullable = true}
---
...
tarantool> s = box.schema.create_space('test', {format = format});
         > _ = s:create_index('pk')
---
...
tarantool> t = {
         >     1,
         >     {
         >         key1 = 'value',
         >         key2 = 10
         >     },
         >     {
         >         2,
         >         3,
         >         {key3 = 20}
         >     }
         > }
---
...
tarantool> t = s:replace(t)
---
...
tarantool> t:update({{'=', 'field2.key1', 'new_value'}})
---
- [1, {'key1': 'new_value', 'key2': 10}, [2, 3, {'key3': 20}]]
...
tarantool> t:update({{'+', 'field3[2]', 1}})
---
- [1, {'key1': 'value', 'key2': 10}, [2, 4, {'key3': 20}]]
...
tarantool> s:update({1}, {{'!', 'field4', 'inserted value'}})
---
- [1, {'key1': 'value', 'key2': 10}, [2, 3, {'key3': 20}], 'inserted value']
...
tarantool> s:update({1}, {{'#', '[2].key2', 1}, {'=', '[3][3].key4', 'value4'}})
---
- [1, {'key1': 'value'}, [2, 3, {'key3': 20, 'key4': 'value4'}], 'inserted value']
...
tarantool> s:upsert({1, {k = 'v'}, {}}, {{'#', '[2].key1', 1}})
---
...
tarantool> s:select{}
---
- - [1, {}, [2, 3, {'key3': 20, 'key4': 'value4'}], 'inserted value']
...

Обратите внимание, что имена полей, которые выглядят как JSON-пути, обрабатываются аналогично доступу к полям кортежа через JSON: сначала весь путь интерпретируется как имя поля; если такого имени не существует, то оно обрабатывается как путь.

Например, для имя поля field.name.like.json, это обновление

object-name:update(..., 'field.name.like.json', ...)

обновит именно это поле целиком, а не ключи field -> name -> like -> json. Если это имя нужно вам как часть большего пути, то его нужно обернутьв кавычки "" или квадратные скобки []:

object-name:update(..., '["field.name.like.json"].next.fields', ...)

Есть несколько правил для обновления через JSON:

Почему обновления с помощью JSON-путей хороши, и их следует предпочитать, когда нужно обновить только часть кортежа:

Справочник по сторонним библиотекам

В данном справочнике описаны сторонние Lua-модули для Tarantool.

For Tarantool Enterprise modules, see the Tarantool EE documentation.

Модуль membership

Этот модуль представляет собой библиотеку membership для Tarantool на основе протокола gossip.

Эта библиотека создает сеть из нескольких экземпляров Tarantool. Сеть сама контролирует себя, помогает участникам обнаружить всех остальных в группе и получать уведомления об изменениях своего статуса с низкой задержкой. Модуль основан на концепциях из Consul или, точнее, алгоритма SWIM.

Модуль membership работает по протоколу UDP и может производить операции даже до инициализации box.cfg.

Структура членов данных

Члены-данные представлены в виде таблиц со следующими полями:

Ниже приведен пример таблицы:

tarantool> membership.myself()
---
uri: localhost:33001
status: alive
incarnation: 1
payload:
    uuid: 2d00c500-2570-4019-bfcc-ab25e5096b73
timestamp: 1522427330993752
...

Справочник по API

Ниже приведен список простых функций, функций шифрования, подписки и параметры модуля membership.

Имя Назначение
Простые функции
init(advertise_host, port) Инициализация модуля membership.
myself() Получение структуры данных текущего экземпляра.
get_member(uri) Получение структуры данных для указанного URI.
members() Получение таблицы со всеми членами группы, известными текущему экземпляру.
pairs() Сокращение для pairs(membership.members()).
add_member(uri) Добавление члена в группу.
probe_uri(uri) Проверка принадлежности члена к группе.
broadcast() Обнаружение участников в локальной сети путем отправки широковещательного сообщения UDP.
set_payload(key, value) Обновление myself().payload и распространение информации.
leave() Корректное исключение из группы.
is_encrypted() Проверка, включено ли шифрование.
Функции шифрования
set_encryption_key(key) Установка ключа для низкоуровневого шифрования сообщений.
get_encryption_key() Получение используемого ключа шифрования.
Функции подписки
subscribe() Подписка на обновления членов таблицы.
unsubscribe() Удаление подписки.
Параметры
PROTOCOL_PERIOD_SECONDS Время отправки сообщений проверки связи напрямую.
ACK_TIMEOUT_SECONDS Время ожидания сообщения подтверждения.
ANTI_ENTROPY_PERIOD_SECONDS Период синхронизации во избежание энтропии.
SUSPECT_TIMEOUT_SECONDS Время ожидания, чтобы перевести члена группы из статуса suspect в dead.
NUM_FAILURE_DETECTION_SUBGROUPS Число членов группы, которые отправляют сообщения проверки связи члену группы в статусе suspect.

Простые функции:

membership.init(advertise_host, port)

Инициализация модуля membership. Привязывает UDP-сокет к 0.0.0.0:<port>, задает значение параметра advertise_uri = <advertise_host>:<port> (передаваемый хост, порт) и значение параметра incarnation = 1.

Функцию init() можно вызвать несколько раз, старый сокет будет закрыт, откроется новый сокет.

Если значение параметра advertise_uri изменится во время очередного выполнения init(), старый URI считается недоступным со статусом DEAD. Чтобы корректно исключить члена из группы, используйте функцию leave().

Параметры:
  • advertise_host (string) – имя хоста или IP-адрес, передаваемый другим членам группы
  • port (number) – привязываемый UDP-порт
возвращает:

true (правда)
тип возвращаемого значения:
 

boolean (логический)
вызывает:

подключенный сокет, если нет ошибки
membership.myself()
возвращает:структура данных члена группы для текущего экземпляра.
тип возвращаемого значения:
 таблица
membership.get_member(uri)
Параметры:
  • uri (string) – advertise_uri для указанного члена группы
возвращает:

структура данных экземпляра с указанным URI.
тип возвращаемого значения:
 

таблица
membership.members()

Получение всех членов группы, известных текущему экземпляру.

Редактирование этой таблицы ни на что не вляет.

возвращает:таблица с URI в качестве ключей и структурой данных члена группы в качестве значений.
тип возвращаемого значения:
 таблица
membership.pairs()

Сокращение для pairs(membership.members()).

возвращает:Lua-итератор

Можно использовать следующим образом:

for uri, member in membership.pairs()
  -- что-то сделать
end
membership.add_member(uri)

Добавление в группу члена с указанным URI и передача информации об этом событии другим членам группы. Достаточно добавить члена группы в один экземпляр, так как все остальные экземпляры в группе со временем получат информацию об этом. Не имеет значения, кто кого добавляет.

Параметры:
  • uri (string) – параметр advertise_uri добавляемого члена группы
возвращает:

true (правда) или нулевое значение nil в случае ошибки
тип возвращаемого значения:
 

boolean (логический)
вызывает:

ошибка анализа, если URI нельзя проанализировать
membership.probe_uri(uri)

Отправка сообщения члену группы, чтобы убедиться, что он включен в группу. Если экземпляр активен со статусом alive, но не включен в группу, происходит его добавление. Если он уже включен в группу, ничего не происходит.

Параметры:
  • uri (string) – параметр advertise_uri члена группы, которому отправляются сообщения проверки связи
возвращает:

true (правда), если ответ возвращается в течение 0.2 секунды, в остальных случаях no response (нет ответа)
тип возвращаемого значения:
 

boolean (логический)
вызывает:

ping was not sent (сообщение проверки связи не отправлено), если имя хоста не разрешено
membership.broadcast()

Обнаружение членов группы в локальной сети путем отправки широковещательного сообщения UDP во все сети, обнаруженные с помощью вызова getifaddrs() на языке C.

возвращает:true (правда), если сообщение отправлено, false (ложь), если getaddrinfo() не выполнена.
тип возвращаемого значения:
 boolean (логический)
membership.set_payload(key, value)

Обновление myself().payload и распространение соответствующей информации вместе со статусом члена группы.

Увеличивает значение параметра incarnation.

Параметры:
  • key (string) – ключ, задаваемый в таблице payload
  • value – дополнительные данные
возвращает:

true (правда)
тип возвращаемого значения:
 

boolean (логический)
membership.leave()

Корректное исключение из группы membership. Узел получает статус выбывшего left, другие члены группы не будут пытаться снова подключить его.

возвращает:true (правда)
тип возвращаемого значения:
 boolean (логический)
membership.is_encrypted()
возвращает:true (правда), если шифрование включено, false в противном случае.
тип возвращаемого значения:
 boolean (логический)

Функции шифрования:

membership.set_encryption_key(key)

Установка ключа, который используется для низкоуровневого шифрования сообщений. Ключ автоматически обрезается или дополняется до 32 байтов. Если значения ключа key нулевое nil, шифрование будет отключено.

Модуль Tarantool crypto.cipher.aes256.cbc занимается шифрованием.

Чтобы обеспечить правильную связь, все члены группы должны быть настроены на использование одного и того же ключа шифрования. В противном случае члены группы получат статус либо dead, либо non-decryptable (невозможно расшифровать).

Параметры:
  • key (string) – ключ шифрования
возвращает:

nil.
membership.get_encryption_key()

Получение используемого ключа шифрования.

возвращает:ключ шифрования или нулевое значение nil, если шифрование отключено.
тип возвращаемого значения:
 строка

Функции подписки:

membership.subscribe()

Подписка на обновления членов таблицы.

возвращает:объект fiber.cond, который передается при каждом изменении таблицы.
тип возвращаемого значения:
 объект
membership.unsubscribe(cond)

Удаление подписки на cond, получаемый с помощью функции subscribe().

Достоверность cond не проверяется.

Параметры:
  • cond – объект fiber.cond, получаемый с помощью функции subscribe()
возвращает:

nil.

Ниже приведен перечень параметров membership. Их можно задать следующим образом:

options = require('membership.options')
options.<параметр> = <значение>
options.PROTOCOL_PERIOD_SECONDS

Период отправки сообщение проверки связи напрямую. Обозначается как T' в протоколе SWIM.

options.ACK_TIMEOUT_SECONDS

Время ожидания сообщения подтверждения после отправки сообщения проверки связи. Если ответ запаздывает, вызывается алгоритм косвенной проверки связи.

options.ANTI_ENTROPY_PERIOD_SECONDS

Период выполнения алгоритма синхронизации во избежание энтропии из протокола SWIM.

options.SUSPECT_TIMEOUT_SECONDS

Время ожидания, чтобы перевести члена группы из статуса suspect в dead.

options.NUM_FAILURE_DETECTION_SUBGROUPS

Число членов группы, которые пытаются отправить сообщения проверки связи члену группы в статусе suspect. Обозначается как k в протоколе SWIM.

Luatest

More about Luatest API see below.

Overview

Tool for testing tarantool applications.

Highlights:

Requirements

Installation

tt rocks install luatest
.rocks/bin/luatest --help # list available options

Usage

Define tests.

-- test/feature_test.lua
local t = require('luatest')
local g = t.group('feature')
-- Default name is inferred from caller filename when possible.
-- For `test/a/b/c_d_test.lua` it will be `a.b.c_d`.
-- So `local g = t.group()` works the same way.

-- Tests. All properties with name staring with `test` are treated as test cases.
g.test_example_1 = function() ... end
g.test_example_n = function() ... end

-- Define suite hooks
t.before_suite(function() ... end)
t.before_suite(function() ... end)

-- Hooks to run once for tests group
g.before_all(function() ... end)
g.after_all(function() ... end)

-- Hooks to run for each test in group
g.before_each(function() ... end)
g.after_each(function() ... end)

-- Hooks to run for a specified test in group
g.before_test('test_example_1', function() ... end)
g.after_test('test_example_2', function() ... end)
-- before_test runs after before_each
-- after_test runs before after_each

-- test/other_test.lua
local t = require('luatest')
local g = t.group('other')
-- ...
g.test_example_2 = function() ... end
g.test_example_m = function() ... end

-- Define parametrized groups
local pg = t.group('pgroup', {{engine = 'memtx'}, {engine = 'vinyl'}})
pg.test_example_3 = function(cg)
    -- Use cg.params here
    box.schema.space.create('test', {
        engine = cg.params.engine,
    })
end

-- Hooks can be specified for one parameter
pg.before_all({engine = 'memtx'}, function() ... end)
pg.before_each({engine = 'memtx'}, function() ... end)
pg.before_test('test_example_3', {engine = 'vinyl'}, function() ... end)

Run tests from a path.

luatest                               # run all tests from the ./test directory
luatest test/integration              # run all tests from the specified directory
luatest test/feature_test.lua         # run all tests from the specified file

Run tests from a group.

luatest feature                       # run all tests from the specified group
luatest other.test_example_2          # run one test from the specified group
luatest feature other.test_example_2  # run tests by group and test name

Note that luatest recognizes an input parameter as a path only if it contains /, otherwise, it will be considered as a group name.

luatest feature                       # considered as a group name
luatest ./feature                     # considered as a path
luatest feature/                      # considered as a path

You can also use -p option in combination with the examples above for running tests matching to some name pattern.

luatest feature -p test_example       # run all tests from the specified group matching to the specified pattern

Luatest automatically requires test/helper.lua file if it’s present. You can configure luatest or run any bootstrap code there.

See the getting-started example in cartridge-cli repo.

Tests order

Use the --shuffle option to tell luatest how to order the tests. The available ordering schemes are group, all and none.

group shuffles tests within the groups.

all randomizes execution order across all available tests. Be careful: before_all/after_all hooks run always when test group is changed, so it may run multiple time.

none is the default, which executes examples within the group in the order they are defined (eventually they are ordered by functions line numbers).

With group and all you can also specify a seed to reproduce specific order.

--shuffle none
--shuffle group
--shuffle all --seed 123
--shuffle all:123 # same as above

To change default order use:

-- test/helper.lua
local t = require('luatest')
t.configure({shuffle = 'group'})

Preloaded hooks

Preloaded hooks extend base hooks. They behave like the pytest fixture with the autouse parameter.

If you run the following test:

Then the hooks are executed in the following sequence:

List of luatest functions

Assertions
assert (value[, message]) Check that value is truthy.
assert_almost_equals (actual, expected, margin[, message]) Check that two floats are close by margin.
assert_covers (actual, expected[, message]) Checks that actual map includes expected one.
assert_lt (left, right[, message]) Compare numbers.
assert_le (left, right[, message])  
assert_gt (left, right[, message])  
assert_ge (left, right[, message])  
assert_equals (actual, expected[, message[, deep_analysis]]) Check that two values are equal.
assert_error (fn, ...) Check that calling fn raises an error.
assert_error_msg_contains (expected_partial, fn, ...)  
assert_error_msg_content_equals (expected, fn, ...) Strips location info from message text.
assert_error_msg_equals (expected, fn, ...) Checks full error: location and text.
assert_error_msg_matches (pattern, fn, ...)  
assert_error_covers (expected, fn, ...) Checks that actual error map includes expected one.
assert_eval_to_false (value[, message]) Alias for assert_not.
assert_eval_to_true (value[, message]) Alias for assert.
assert_items_exclude (actual, expected[, message]) Checks that one table does not include any items of another, irrespective of their keys.
assert_items_include (actual, expected[, message]) Checks that one table includes all items of another, irrespective of their keys.
assert_is (actual, expected[, message]) Check that values are the same.
assert_is_not (actual, expected[, message]) Check that values are not the same.
assert_items_equals (actual, expected[, message]) Checks that two tables contain the same items, irrespective of their keys.
assert_nan (value[, message])  
assert_not (value[, message]) Check that value is falsy.
assert_not_almost_equals (actual, expected, margin[, message]) Check that two floats are not close by margin
assert_not_covers (actual, expected[, message]) Checks that map does not contain the other one.
assert_not_equals (actual, expected[, message]) Check that two values are not equal.
assert_not_nan (value[, message])  
assert_not_str_contains (actual, expected[, is_pattern[, message]]) Case-sensitive strings comparison.
assert_not_str_icontains (value, expected[, message]) Case-insensitive strings comparison.
assert_str_contains (value, expected[, is_pattern[, message]]) Case-sensitive strings comparison.
assert_str_icontains (value, expected[, message]) Case-insensitive strings comparison.
assert_str_matches (value, pattern[, start=1[, final=value:len() [, message]]]) Verify a full match for the string.
assert_type (value, expected_type[, message]) Check value’s type.
Flow control
fail (message) Stops a test due to a failure.
fail_if (condition, message) Stops a test due to a failure if condition is met.
xfail (message) Mark test as xfail.
xfail_if (condition, message) Mark test as xfail if condition is met.
skip (message) Skip a running test.
skip_if (condition, message) Skip a running test if condition is met.
success () Stops a test with a success.
success_if (condition) Stops a test with a success if condition is met.
Suite and groups
after_suite (fn) Add after suite hook.
before_suite (fn) Add before suite hook.
group (name) Create group of tests.

XFail

The xfail mark makes test results to be interpreted vice versa: it’s threated as passed when an assertion fails, and it fails if no errors are raised. It allows one to mark a test as temporarily broken due to a bug in some other component which can’t be fixed immediately. It’s also a good practice to keep xfail tests in sync with an issue tracker.

local g = t.group()
g.test_fail = function()
    t.xfail('Must fail no matter what')
    t.assert_equals(3, 4)
end

XFail only applies to the errors raised by the luatest assertions. Regular Lua errors still cause the test failure.

Capturing output

By default runner captures all stdout/stderr output and shows it only for failed tests. Capturing can be disabled with -c flag.

Tests repeating

Runners can repeat tests with flags -r / --repeat (to repeat all the tests) or -R / --repeat-group (to repeat all the tests within the group).

Parametrization

Test group can be parametrized.

local g = t.group('pgroup', {{a = 1, b = 4}, {a = 2, b = 3}})

g.test_params = function(cg)
    ...
    log.info('a = %s', cg.params.a)
    log.info('b = %s', cg.params.b)
    ...
end

Group can be parametrized with a matrix of parameters using luatest.helpers:

local g = t.group('pgroup', t.helpers.matrix({a = {1, 2}, b = {3, 4}}))
-- Will run:
-- * a = 1, b = 3
-- * a = 1, b = 4
-- * a = 2, b = 3
-- * a = 2, b = 4

Each test will be performed for every params combination. Hooks will work as usual unless there are specified params. The order of execution in the hook group is determined by the order of declaration.

-- called before every test
g.before_each(function(cg) ... end)

-- called before tests when a == 1
g.before_each({a = 1}, function(cg) ... end)

-- called only before the test when a == 1 and b == 3
g.before_each({a = 1, b = 3}, function(cg) ... end)

-- called before test named 'test_something' when a == 1
g.before_test('test_something', {a = 1}, function(cg) ... end)

--etc

Test from a parameterized group can be called from the command line in such a way:

luatest pgroup.a:1.b:4.test_params
luatest pgroup.a:2.b:3.test_params

Note that values for a and b have to match to defined group params. The command below will give you an error because such params are not defined for the group.

luatest pgroup.a:2.b:2.test_params  # will raise an error

Test helpers

There are helpers to run tarantool applications and perform basic interaction with it. If application follows configuration conventions it is possible to use options to configure server instance and helpers at the same time. For example http_port is used to perform http request in tests and passed in TARANTOOL_HTTP_PORT to server process.

local server = luatest.Server:new({
    command = '/path/to/executable.lua',
    -- arguments for process
    args = {'--no-bugs', '--fast'},
    -- additional envars to pass to process
    env = {SOME_FIELD = 'value'},
    -- passed as TARANTOOL_WORKDIR
    workdir = '/path/to/test/workdir',
    -- passed as TARANTOOL_HTTP_PORT, used in http_request
    http_port = 8080,
    -- passed as TARANTOOL_LISTEN, used in connect_net_box
    net_box_port = 3030,
    -- passed to net_box.connect in connect_net_box
    net_box_credentials = {user = 'username', password = 'secret'},
})
server:start()
-- Wait until server is ready to accept connections.
-- This may vary from app to app: for one server:connect_net_box() is enough,
-- for another more complex checks are required.
luatest.helpers.retrying({}, function() server:http_request('get', '/ping') end)

-- http requests
server:http_request('get', '/path')
server:http_request('post', '/path', {body = 'text'})
server:http_request('post', '/path', {json = {field = value}, http = {
    -- http client options
    headers = {Authorization = 'Basic ' .. credentials},
    timeout = 1,
}})

-- This method throws error when response status is outside of then range 200..299.
-- To change this behaviour, path `raise = false`:
t.assert_equals(server:http_request('get', '/not_found', {raise = false}).status, 404)
t.assert_error(function() server:http_request('get', '/not_found') end)

-- using net_box
server:connect_net_box()
server:eval('return do_something(...)', {arg1, arg2})
server:call('function_name', {arg1, arg2})
server:exec(function() return box.info() end)
server:stop()

luatest.Process:start(path, args, env) provides low-level interface to run any other application.

There are several small helpers for common actions:

luatest.helpers.uuid('ab', 2, 1) == 'abababab-0002-0000-0000-000000000001'

luatest.helpers.retrying({timeout = 1, delay = 0.1}, failing_function, arg1, arg2)
-- wait until server is up
luatest.helpers.retrying({}, function() server:http_request('get', '/status') end)

luacov integration

When running integration tests with coverage collector enabled, luatest automatically starts new tarantool instances with luacov enabled. So coverage is collected from all the instances. However this has some limitations:

Development

Contributing

Bug reports and pull requests are welcome on at https://github.com/tarantool/luatest.

License

MIT

Module luatest.helpers

Collection of test helpers.

Functions

matrix (parameters_values)

Return all combinations of parameters. Accepts params“ names and thier every possible value.

helpers.matrix({a = {1, 2}, b = {3, 4}})

{
  {a = 1, b = 3},
  {a = 2, b = 3},
  {a = 1, b = 4},
  {a = 2, b = 4},
}

Parameters:

  • parameters_values: (tab)

retrying (config, fn, …)

Keep calling fn until it returns without error. Throws last error if config.timeout is elapsed. Default options are taken from helpers.RETRYING_TIMEOUT and helpers.RETRYING_DELAY.

helpers.retrying({}, fn, arg1, arg2)
helpers.retrying({timeout = 2, delay = 0.5}, fn, arg1, arg2)

Parameters:

  • config:
    • timeout: (number)
    • delay: (number)
  • fn: (func)
  • …: args

uuid (a, …)

Generates uuids from its 5 parts. Strings are repeated and numbers are padded to match required part length. If number of arguments is less than 5 then first and last arguments are used for corresponding parts, missing parts are set to 0.

'aaaaaaaa-0000-0000-0000-000000000000' == uuid('a')
'abababab-0000-0000-0000-000000000001' == uuid('ab', 1)
'00000001-0002-0000-0000-000000000003' == uuid(1, 2, 3)
'11111111-2222-0000-0000-333333333333' == uuid('1', '2', '3')
'12121212-3434-5656-7878-909090909090' == uuid('12', '34', '56', '78', '90')

Parameters:

  • a: first part
  • …: parts

Module luatest.justrun

Simple Tarantool runner and output catcher.

Sometimes it is necessary to run tarantool with particular arguments and verify its output. luatest.server provides a supervisor like interface: an instance is started, calls box.cfg() and we can communicate with it using net.box. Another helper in tarantool/tarantool, test.interactive_tarantool , aims to solve all the problems around readline console and also provides ability to communicate with the instance interactively.

However, there is nothing like „just run tarantool with given args and give me its output“.

Functions

tarantool (dir, env, args[, opts])

Run tarantool in given directory with given environment and command line arguments and catch its output.

Expects JSON lines as the output and parses it into an array (it can be disabled using nojson option).

Options:

  • nojson (boolean, default: false)

Don’t attempt to decode stdout as a stream of JSON lines, return as is.

  • stderr (boolean, default: false)

Collect stderr and place it into the stderr field of the return value

  • quote_args (boolean, default: false)

Quote CLI arguments before concatenating them into a shell command.

Parameters:

  • dir: (string) Directory where the process will run.
  • env: (table) Environment variables for the process.
  • args: (table) Options that will be passed when the process starts.
  • opts: (table) Custom options: nojson, stderr and quote_args. (optional)

Returns:

(table)

Module luatest.hooks

Provide extra methods for hooks.

Preloaded hooks extend base hooks. They behave like the pytest fixture with the autouse parameter.

Usage:

local hooks = require('luatest.hooks')

hooks.before_suite_preloaded(...)
hooks.after_suite_preloaded(...)

hooks.before_all_preloaded(...)
hooks.after_all_preloaded(...)

hooks.before_each_preloaded(...)
hooks.after_each_preloaded(...)

Functions

export.after_all_preloaded (fn)

Register preloaded after hook in the all scope. It will be done after the classic after_all() hook in the tests.

Parameters:

export.after_each_preloaded (fn)

Register preloaded after hook in the each scope. It will be done after the classic after_each() hook in the tests.

Parameters:

export.after_suite_preloaded (fn)

Register preloaded after hook in the suite scope. It will be done after the classic after_suite() hook in the tests.

Parameters:

export.before_all_preloaded (fn)

Register preloaded before hook in the all scope. It will be done before the classic before_all() hook in the tests.

Parameters:

export.before_each_preloaded (fn)

Register preloaded before hook in the each scope. It will be done before the classic before_each() hook in the tests.

Parameters:

export.before_suite_preloaded (fn)

Register preloaded before hook in the suite scope. It will be done before the classic before_suite() hook in the tests.

Parameters:

Module luatest.treegen

Working tree generator.

Generates a tree of Lua files using provided templates and filenames.

Usage:

local t = require('luatest')
local treegen = require('luatest.treegen')

local g = t.group()

g.test_foo = function(g)
    treegen.add_template('^.*$', 'test_script')
    local dir = treegen.prepare_directory({'foo/bar.lua', 'main.lua'})
    ...
end

Functions

add_template (pattern, template)

Save the template with the given pattern.

Parameters:

prepare_directory (contents[, replacements])

Create a temporary directory with given contents.

The contents are generated using templates added by treegen.add_template().

Parameters:

Returns:

string

Usage:

Example for {'foo/bar.lua', 'baz.lua'}:

/
+ tmp/
  + rfbWOJ/
    + foo/
    | + bar.lua
    + baz.lua

The return value is '/tmp/rfbWOJ' for this example.

remove_template (pattern)

Remove the template by pattern.

Parameters:

write_file (directory, filename, content)

Write provided content into the given directory.

Parameters:

Returns:

string

Class luatest.group

Tests group.

To add new example add function at key starting with test .

Group hooks run always when test group is changed. So it may run multiple times when --shuffle option is used.

Instance methods

Group.mt.after_all (fn)

Add callback to run once after all tests in the group.

Parameters:

  • fn:

Group.mt.after_each (fn)

Add callback to run after each test in the group.

Parameters:

  • fn:

Group.mt.before_all (fn)

Add callback to run once before all tests in the group.

Parameters:

  • fn:

Group.mt.before_each (fn)

Add callback to run before each test in the group.

Parameters:

  • fn:

Group.mt:initialize ([name])

Parameters:

  • name: (string) Default name is inferred from caller filename when possible.For test/a/b/c_d_test.lua it will be a.b.c_d . (optional)

Returns:

Group instance

Class luatest.http_response

Class to provide helper methods for HTTP responses

Instance getter methods

HTTPResponse.getters

For backward compatibility this methods should be accessed as object’s fields (eg., response.json.id ).

They are not assigned to object’s fields on initialization to be evaluated lazily and to be able to throw errors.

HTTPResponse.getters:json ()

Parse json from body.

Usage:

response.json.id

HTTPResponse.mt:is_successful ()

Check that status code is 2xx.

Class luatest.runner

Class to run test suite.

Functions

Runner.is_test_name (s)

Check that string matches the name of a test method. Default rule is that is starts with „test“

Parameters:

  • s:

Runner.run ([args=_G.args[, options]])

Main entrypoint to run test suite.

Parameters:

  • args: (tab) List of CLI arguments (default $(def))
  • options:
    • verbosity: (int) (optional)
    • fail_fast: (bool) (default $(def))
    • output_file_name: (string) Filename for JUnit report (optional)
    • exe_repeat: (int) Times to repeat each test (optional)
    • exe_repeat_group: (int) Times to repeat each group of tests (optional)
    • tests_pattern: (tab) Patterns to filter tests (optional)
    • tests_names: (tab) List of test names or groups to run (optional)
    • paths: (tab) List of directories to load tests from. (default $(def))
    • load_tests: (func) Function to load tests. Called once for every item in paths . (optional)
    • shuffle: (string) Shuffle method (none, all, group) (default $(def))
    • seed: (int) Random seed for shuffle (optional)
    • output: (string) Output formatter (text, tap, junit, nil) (default $(def))

Runner.split_test_method_name (someName)

Split some.group.name.method into some.group.name and method . Returns nil, input if input value does not have a dot.

Parameters:

  • someName:

Runner:expand_group (group)

Exrtact all test methods from group.

Parameters:

  • group:

Class luatest.server

Class to manage Tarantool instances.

Functions

Server.build_listen_uri (server_alias[, extra_path])

Build a listen URI based on the given server alias and extra path. The resulting URI: <Server.vardir>/[<extra_path>/]<server_alias>.sock. Provide a unique alias or extra path to avoid collisions with other sockets. For now, only UNIX sockets are supported.

Parameters:

  • server_alias: (string) Server alias.
  • extra_path: (string) Extra path relative to the Server.vardir directory. (optional)

Returns:

string

Server:assert_follows_upstream (server_id)

Assert that the server follows the source node with the given ID. Meaning that it replicates from the remote node normally, and has already joined and subscribed.

Parameters:

  • server_id: (number) Server ID.

Server:call (fn_name[, args[, options]])

Call remote function on the server by name.

This is a shortcut for server.net_box:call() .

Parameters:

  • fn_name: (string)
  • args: (tab) (optional)
  • options: (tab) (optional)

Server:connect_net_box ()

Establish net.box connection. It’s available in net_box field.

Server:copy_datadir ()

Copy contents of the data directory into the server’s working directory. Invoked on the server’s start.

Server:drop ()

Stop the server and save its artifacts if the test fails. This function should be used only at the end of the test (after_test, after_each, after_all hooks) to terminate the server process. Besides process termination, it saves the contents of the server working directory to the <vardir>/artifacts directory for further analysis if the test fails.

Server:eval (code[, args[, options]])

Evaluate Lua code on the server.

This is a shortcut for server.net_box:eval() .

Parameters:

  • code: (string)
  • args: (tab) (optional)
  • options: (tab) (optional)

Server:exec (fn[, args[, options]])

Run given function on the server.

Much like Server:eval , but takes a function instead of a string. The executed function must have no upvalues (closures). Though it may use global functions and modules (like box , os , etc.)

Parameters:

  • fn: (function)
  • args: (tab) (optional)
  • options: (tab) (optional)

Usage:

local vclock = server:exec(function()
    return box.info.vclock
end)

local sum = server:exec(function(a, b)
    return a + b
end, {1, 2})
-- sum == 3

local t = require('luatest')
server:exec(function()
    -- luatest is available via `t` upvalue
    t.assert_equals(math.pi, 3)
end)
-- mytest.lua:12: expected: 3, actual: 3.1415926535898

Server:get_box_cfg ()

A simple wrapper around the Server:exec() method to get the box.cfg value from the server.

Returns:

table

Server:get_downstream_vclock (server_id)

Get vclock acknowledged by another node to the current server.

Parameters:

  • server_id: (number) Server ID.

Returns:

table

Server:get_election_term ()

Get the election term as seen by the server.

Returns:

number

Server:get_instance_id ()

Get ID of the server instance.

Returns:

number

Server:get_instance_uuid ()

Get UUID of the server instance.

Returns:

string

Server:get_synchro_queue_term ()

Get the synchro term as seen by the server.

Returns:

number

Server:get_vclock ()

Get the server’s own vclock, including the local component.

Returns:

table

Server:grep_log (pattern[, bytes_num[, opts]])

Search a string pattern in the server’s log file. If the server has crashed, opts.filename is required.

Parameters:

  • pattern: (string) String pattern to search in the server’s log file.
  • bytes_num: (number) Number of bytes to read from the server’s log file. (optional)
  • opts:
    • reset: (bool) Reset the result when Tarantool %d+.%d+.%d+-.*%d+-g.* pattern is found, which means that the server was restarted.Defaults to true . (optional)
    • filename: (string) Path to the server’s log file.Defaults to box.cfg.log . (optional)

Returns:

string|nil

Server:http_request (method, path[, options])

Perform HTTP request.

Parameters:

  • method: (string)
  • path: (string)
  • options:
    • body: (string) request body (optional)
    • json: data to encode as JSON into request body (optional)
    • http: (tab) other options for HTTP-client (optional)
    • raise: (bool) raise error when status is not in 200..299. Default to true. (optional)

Returns:

response object from HTTP client with helper methods.

Raises:

HTTPRequest error when response status is not 200.

See also:

  • luatest.http_response

Server:make_socketdir ()

Make directory for the server’s Unix socket. Invoked on the server’s start.

Server:make_workdir ()

Make the server’s working directory. Invoked on the server’s start.

Server:new ([object[, extra]])

Build a server object.

Parameters:

  • object: Table with the entries listed below. (optional)
    • command: (string) Executable path to run a server process with.Defaults to the internal server_instance.lua script. If a custom pathis provided, it should correctly process all env variables listed belowto make constructor parameters work. (optional)
    • args: (tab) Arbitrary args to run object.command with. (optional)
    • env: (tab) Pass the given env variables into the server process. (optional)
    • chdir: (string) Change to the given directory before runningthe server process. (optional)
    • alias: (string) Alias for the new server and the value of the.. code-block:: lua TARANTOOL_ALIAS env variable which is passed into the server process.Defaults to „server“. (optional)
    • workdir: (string) Working directory for the new server and thevalue of the TARANTOOL_WORKDIR env variable which is passed into theserver process. The directory path will be created on the server start.Defaults to <vardir>/<alias>-<random id>. (optional)
    • datadir: (string) Directory path whose contents will be recursivelycopied into object.workdir on the server start. (optional)
    • http_port: (number) Port for HTTP connection to the new server andthe value of the TARANTOOL_HTTP_PORT env variable which is passed intothe server process.Not supported in the default server_instance.lua script. (optional)
    • net_box_port: (number) Port for the net.box connection to the newserver and the value of the TARANTOOL_LISTEN env variable which is passedinto the server process. (optional)
    • net_box_uri: (string) URI for the net.box connection to the newserver and the value of the TARANTOOL_LISTEN env variable which is passedinto the server process. If it is a Unix socket, the corresponding socketdirectory path will be created on the server start. (optional)
    • net_box_credentials: (tab) Override the default credentials for the.. code-block:: lua net.box connection to the new server. (optional)
    • box_cfg: (tab) Extra options for box.cfg() and the value of the.. code-block:: lua TARANTOOL_BOX_CFG env variable which is passed into the server process. (optional)
    • config_file: (string) Declarative YAML configuration for a serverinstance. Used to deduce advertise URI to connect net.box to the instance.The special value „“ means running without --config <...> CLI option(but still passes --name <alias>). (optional)
    • remote_config: (tab) If config_file is not passed, this configvalue is used to deduce advertise URI to connect net.box to the instance. (optional)
  • extra: (tab) Table with extra properties for the server object. (optional)

Returns:

table

Server:play_wal_until_synchro_queue_is_busy ()

Play WAL until the synchro queue becomes busy. WAL records go one by one. The function is needed, because during box.ctl.promote() it is not known for sure which WAL record is PROMOTE - first, second, third? Even if known, it might change in the future. WAL delay should already be started before the function is called.

Server:restart ([params[, opts]])

Restart the server with the given parameters. Optionally waits until the server is ready.

Parameters:

  • params: (tab) Parameters to restart the server with.Like command , args , env , etc. (optional)
  • opts:
    • wait_until_ready: (bool) Wait until the server is ready.Defaults to true unless a custom executable path was provided whilebuilding the server object. (optional)

See also:

  • luatest.server.Server:new

Server:start ([opts])

Start a server. Optionally waits until the server is ready.

Parameters:

  • opts:
    • wait_until_ready: (bool) Wait until the server is ready.Defaults to true unless a custom executable was provided while buildingthe server object. (optional)

Server:stop ()

Stop the server. Waits until the server process is terminated.

Server:update_box_cfg (cfg)

A simple wrapper around the Server:exec() method to update the box.cfg value on the server.

Parameters:

  • cfg: (tab) Box configuration settings.

Server:wait_for_downstream_to (server)

Wait for the given server to reach at least the same vclock as the local server. Not including the local component, of course.

Parameters:

  • server: (tab) Server’s object.

Server:wait_for_election_leader ()

Wait for the server to become a writable election leader.

Server:wait_for_election_state (state)

Wait for the server to enter the given election state. Note that if it becomes a leader, it does not mean it is already writable.

Parameters:

  • state: (string) Election state to wait for.

Server:wait_for_election_term (term)

Wait for the server to reach at least the given election term.

Parameters:

  • term: (string) Election term to wait for.

Server:wait_for_synchro_queue_term (term)

Wait for the server to reach at least the given synchro term.

Parameters:

  • term: (number) Synchro queue term to wait for.

Server:wait_for_vclock (vclock)

Wait until the server’s own vclock reaches at least the given value. Including the local component.

Parameters:

  • vclock: (tab) Server’s own vclock to reach.

Server:wait_for_vclock_of (other_server)

Wait for the server to reach at least the same vclock as the other server. Not including the local component, of course.

Parameters:

  • other_server: (tab) Other server’s object.

Server:wait_until_election_leader_found ()

Wait for the server to discover an election leader.

Server:wait_until_ready ()

Wait until the server is ready after the start. A server is considered ready when its _G.ready variable becomes true .

Class luatest.replica_set

Class to manage groups of Tarantool instances with the same data set.

Functions

ReplicaSet:add_server (server)

Add the server object to the replica set. The added server object should be built via the ReplicaSet:build_server function.

Parameters:

  • server: (tab) Server object to be added to the replica set.

ReplicaSet:build_and_add_server ([config])

Build a server object and add it to the replica set.

Parameters:

  • config: (tab) Configuration for the new server. (optional)

Returns:

table

See also:

  • luatest.server.Server:new

ReplicaSet:build_server ([config])

Build a server object for the replica set.

Parameters:

  • config: (tab) Configuration for the new server. (optional)

Returns:

table

See also:

  • luatest.server.Server:new

ReplicaSet:delete_server (alias)

Delete the server object from the replica set by the given server alias.

Parameters:

  • alias: (string) Server alias.

ReplicaSet:drop ()

Stop all servers in the replica set and save their artifacts if the test fails. This function should be used only at the end of the test (after_test, after_each, after_all hooks) to terminate all server processes in the replica set. Besides process termination, it saves the contents of each server working directory to the <vardir>/artifacts directory for further analysis if the test fails.

ReplicaSet:get_leader ()

Get a server which is a writable node in the replica set.

Returns:

table

ReplicaSet:get_server (alias)

Get the server object from the replica set by the given server alias.

Parameters:

  • alias: (string) Server alias.

Returns:

table|nil

ReplicaSet:new ([object])

Build a replica set object.

Parameters:

  • object: Table with the entries listed below. (optional)
    • servers: (tab) List of server configurations to build serverobjects from and add them to the new replica set. See an example below. (optional)

Returns:

table

See also:

  • luatest.server.Server:new

Usage:

local ReplicaSet = require('luatest.replica_set')
local Server = require('luatest.server')
local box_cfg = {
    replication_timeout = 0.1,
    replication_connect_timeout = 10,
    replication_sync_lag = 0.01,
    replication_connect_quorum = 3,
    replication = {
        Server.build_listen_uri('replica1'),
        Server.build_listen_uri('replica2'),
        Server.build_listen_uri('replica3'),
    },
}
local replica_set = ReplicaSet:new({
    servers = {
        {alias = 'replica1', box_cfg = box_cfg},
        {alias = 'replica2', box_cfg = box_cfg},
        {alias = 'replica3', box_cfg = box_cfg},
    }
})
replica_set:start()
replica_set:wait_for_fullmesh()

ReplicaSet:start ([opts])

Start all servers in the replica set. Optionally waits until all servers are ready.

Parameters:

  • opts: Table with the entries listed below. (optional)
    • wait_until_ready: (bool) Wait until all servers are ready.Defaults to true . (optional)

ReplicaSet:stop ()

Stop all servers in the replica set.

ReplicaSet:wait_for_fullmesh ([opts])

Wait until every node is connected to every other node in the replica set.

Parameters:

  • opts: Table with the entries listed below. (optional)
    • timeout: (number) Timeout in seconds to wait for full mesh.Defaults to 60. (optional)
    • delay: (number) Delay in seconds between attempts to check full mesh.Defaults to 0.1. (optional)

Class luatest.cbuilder

Configuration builder.

It allows to construct a declarative configuration for a test case using less boilerplace code/options, especially when a replicaset is to be tested, not a single instance. All the methods support chaining (return the builder object back).

Usage:

local config = Builder:new()
    :add_instance('instance-001', {
        database = {
            mode = 'rw',
        },
    })
    :add_instance('instance-002', {})
    :add_instance('instance-003', {})
    :config()

By default, all instances are added to replicaset-001 in group-001,
but it's possible to select a different replicaset and/or group:

local config = Builder:new()
    :use_group('group-001')
    :use_replicaset('replicaset-001')
    :add_instance(<...>)
    :add_instance(<...>)
    :add_instance(<...>)

    :use_group('group-002')
    :use_replicaset('replicaset-002')
    :add_instance(<...>)
    :add_instance(<...>)
    :add_instance(<...>)

    :config()

The default credentials and iproto options are added to
setup replication and to allow a test to connect to the
instances.

There is a few other methods:

* :set_replicaset_option('foo.bar', value)
* :set_instance_option('instance-001', 'foo.bar', value)

Functions

Builder:add_instance (instance_name, iconfig)

Add an instance with the given options to the selected replicaset.

Parameters:

Builder:config ()

Return the resulting configuration.

Builder:new ([config])

Build a config builder object.

Parameters:

Builder:set_global_option (path, value)

Set option to the cluster config.

Parameters:

Builder:set_group_option (path, value)

Set an option for the selected group.

Parameters:

Builder:set_replicaset_option (path, value)

Set an option for the selected replicaset.

Parameters:

Builder:use_group (group_name)

Select a group for following calls.

Parameters:

Builder:use_replicaset (replicaset_name)

Select a replicaset for following calls.

Parameters:

Модуль vshard

В модуле vshard реализована функция продвинутого шардинга (сегментирования), которая основывается на понятии виртуального сегмента и позволяет осуществлять горизонтальное масштабирование в Tarantool.

To learn how sharding works in Tarantool, refer to the Sharding page.

Стоит также обратиться к руководству по быстрому запуску. Ниже приводятся справочники по модулю vshard:

Справочник по настройке

Примечание

Starting with the 3.0 version, the recommended way of configuring Tarantool is using a configuration file. Configuring Tarantool in code is considered a legacy approach.

Базовые параметры

sharding

Поле, которое определяет логическую топологию сегментированного кластера Tarantool.

Тип: таблица
По умолчанию: false (ложь)
Динамический: да
weights

Поле, которое определяет конфигурацию относительного веса для каждой пары зон в наборе реплик.

Тип: таблица
По умолчанию: false (ложь)
Динамический: да
shard_index

Название или id TREE-индекса по идентификатору сегмента. Спейсы без этого индекса не задействованы в шардированном кластере Tarantool и при необходимости могут быть использованы как обычные спейсы. Необходимо указать первую часть индекса, остальные части являются необязательными.

Тип: непустая строка или неотрицательное целое число
По умолчанию: «bucket_id» (идентификатор сегмента)
Динамический: нет
bucket_count

Общее число сегментов в кластере.

Это число должно быть на несколько порядков больше, чем потенциальное число узлов кластера, учитывая потенциальное масштабирование в обозримом будущем.

Пример:

Если предполагаемое количество узлов равно M, тогда набор данных должен быть разделен на 100M или даже 1000M сегментов, в зависимости от запланированного масштабирования. Это число, безусловно, больше потенциального числа узлов кластера в проектируемой системе.

Следует помнить, что слишком большое число сегментов может привести к необходимости выделять больше памяти для хранения информации о маршрутизации. С другой стороны, недостаточное число сегментов может привести к снижению степени детализации при балансировке.

Тип: число
По умолчанию: 3000
Динамический: нет
collect_bucket_garbage_interval

Deprecated since: 0.1.17.

Интервал между действиями сборщика мусора в секундах.

Тип: число
По умолчанию: 0.5
Динамический: да
collect_lua_garbage

Deprecated since: 0.1.20.

Если задано значение true (правда), периодически вызывается Lua-функция collectgarbage().

Тип: логический
По умолчанию: нет
Динамический: да
sync_timeout

Время ожидания синхронизации старого мастера с репликами перед сменой мастера. Используется при переключении мастера или при вызове функции sync() вручную.

Тип: число
По умолчанию: 1
Динамический: да
rebalancer_disbalance_threshold

A maximum bucket disbalance threshold, in percent. The disbalance is calculated for each replica set using the following formula:

|эталонное_число_сегментов - фактическое_число_сегментов| / эталонное_число_сегментов * 100
Тип: число
По умолчанию: 1
Динамический: да
rebalancer_max_receiving

Максимальное количество сегментов, которые может получить параллельно один набор реплик. Это число должно быть ограничено, так как при добавлении нового набора реплик в кластер балансировщик отправляет очень большое количество сегментов из существующих наборов реплик в новый набор реплик. Это создает большую нагрузку на новый набор реплик.

Пример:

Предположим, rebalancer_max_receiving = 100, число сегментов в bucket_count = 1000. Есть 3 набора реплик с 333, 333 и 334 сегментами соответственно. При добавлении нового набора реплик эталонное_число_сегментов становится равным 250. Вместо того, чтобы сразу получить все 250 сегментов, новый набор реплик получит последовательно 100, 100 и 50 сегментов.

Тип: число
По умолчанию: 100
Динамический: да
rebalancer_max_sending

Степень параллельности для параллельной балансировки.

Используется только для хранилищ, для роутеров игнорируется.

Максимальное значение: 15.

Тип: число
По умолчанию: 1
Динамический: да
discovery_mode

Режим работы файбера обнаружения сегментов: on/off/once. Подробнее.

Тип: строка
По умолчанию: «on»
Динамический: да
sched_move_quota

A scheduler’s bucket move quota used by the rebalancer.

sched_move_quota defines how many bucket moves can be done in a row if there are pending storage refs. Then, bucket moves are blocked and a router continues making map-reduce requests.

See also: sched_ref_quota.

Тип: число
По умолчанию: 1
Динамический: да
sched_ref_quota

A scheduler’s storage ref quota used by a router’s map-reduce API. For example, the vshard.router.map_callrw() function implements consistent map-reduce over the entire cluster.

sched_ref_quota defines how many storage refs, therefore map-reduce requests, can be executed on the storage in a row if there are pending bucket moves. Then, storage refs are blocked and the rebalancer continues bucket moves.

See also: sched_move_quota.

Тип: число
Default: 300
Динамический: да

Параметры набора реплик

uuid

Уникальный идентификатор набора реплик.

Тип:
По умолчанию:
Динамическое:
weight

Вес набора реплик. Для получения подробной информации см. раздел Вес набора реплик.

Тип:
По умолчанию: 1
Динамическое:
master

Turns on automated master discovery in a replica set if set to auto. Applicable only to the configuration of a router; the storage configuration ignores this parameter.

The parameter should be specified per replica set. The configuration is not compatible with a manual master selection.

Examples

Correct configuration:

config = {
    sharding = {
        <replicaset uuid> = {
            master = 'auto',
            replicas = {...},
        },
        ...
    },
    ...
}

Incorrect configuration:

config = {
    sharding = {
        <replicaset uuid> = {
            master = 'auto',
            replicas = {
                <replica uuid1> = {
                    master = true,
                    ...
                },
                <replica uuid2> = {
                    master = false,
                    ...
                },
            },
        },
        ...
    },
    ...
}

If the configuration is incorrect, it is not applied, and the vshard.router.cfg() call throws an error.

If the master parameter is set to auto for some replica sets, the router goes to these replica sets, discovers the master in each of them, and periodically checks if the master instance still has its master status. When the master in the replica set stops being a master, the router goes around all the nodes of the replica set to find out which one is the new master.

Without this setting, the router cannot detect master nodes in the configured replica sets on its own. It relies only on how they are specified in the configuration. This becomes a problem when the master changes, and the change is not delivered to the router’s configuration: for instance, in case the router doesn’t rely on a central configuration provider or the provider cannot deliver a new configuration due to some reason.

Тип: строка
Default: nil
Динамический: да

API Reference

This section represents public and internal API for the router and the storage.

Router API

Subsection Methods
Router public API
Router internal API

Router public API

vshard.router.bootstrap()

Perform the initial cluster bootstrap and distribute all buckets across the replica sets.

Параметры:
  • timeout – a number of seconds before ending a bootstrap attempt as unsuccessful. Recreate the cluster in case of bootstrap timeout.
  • if_not_bootstrapped – by default is set to false that means raise an error, when the cluster is already bootstrapped. True means consider an already bootstrapped cluster a success.

Example:

vshard.router.bootstrap({timeout = 4, if_not_bootstrapped = true})

Примечание

To detect whether a cluster is bootstrapped, vshard looks for at least one bucket in the whole cluster. If the cluster was bootstrapped only partially (for example, due to an error during the first bootstrap), then it will be considered a bootstrapped cluster on a next bootstrap call with if_not_bootstrapped. So this is still a bad practice. Avoid calling bootstrap() multiple times.

vshard.router.cfg(cfg)

Configure the database and start sharding for the specified router instance.

Параметры:
  • cfg – a configuration table
vshard.router.new(name, cfg)

Create a new router instance. vshard supports multiple routers in a single Tarantool instance. Each router can be connected to any vshard cluster, and multiple routers can be connected to the same cluster.

A router created via vshard.router.new() works in the same way as a static router, but the method name is preceded by a colon (vshard.router:method_name(...)), while for a static router the method name is preceded by a period (vshard.router.method_name(...)).

A static router can be obtained via the vshard.router.static() method and then used like a router created via the vshard.router.new() method.

Примечание

box.cfg is shared among all the routers of a single instance.

Параметры:
  • name – a router instance name. This name is used as a prefix in logs of the router and must be unique within the instance
  • cfg – a configuration table
Return:

a router instance, if created successfully; otherwise, nil and an error object
vshard.router.call(bucket_id, mode, function_name, {argument_list}, {options})

Call the function identified by function-name on the shard storing the bucket identified by bucket_id. See the Processing requests section for details on function operation.

Параметры:
  • bucket_id – a bucket identifier
  • mode – either a string = „read“|“write“, or a map with mode=“read“|“write“ and/or prefer_replica=true|false and/or balance=true|false.
  • function_name – a function to execute
  • argument_list – an array of the function’s arguments
  • options –
    • timeout — a request timeout, in seconds. If the router cannot identify a shard with the specified bucket_id, it will retry until the timeout is reached.
    • other net.box options, such as is_async, buffer, on_push are also supported.

The mode parameter has two possible forms: a string or a map. Examples of the string form are: 'read', 'write'. Examples of the map form are: {mode='read'}, {mode='write'}, {mode='read', prefer_replica=true}, {mode='read', balance=true}, {mode='read', prefer_replica=true, balance=true}.

If 'write' is specified then the target is the master.

If prefer_replica=true is specified then the preferred target is one of the replicas, but the target is the master if there is no conveniently available replica.

It may be good to specify prefer_replica=true for functions which are expensive in terms of resource use, to avoid slowing down the master.

If balance=true then there is load balancing—reads are distributed over all the nodes in the replica set in round-robin fashion, with a preference for replicas if prefer_replica=true is also set.

Return:

The original return value of the executed function, or nil and error object. The error object has a type attribute equal to ShardingError or one of the regular Tarantool errors (ClientError, OutOfMemory, SocketError, etc.).

ShardingError is returned on errors specific for sharding: the master is missing, wrong bucket id, etc. It has an attribute code containing one of the values from the vshard.error.code.* LUA table, an optional attribute containing a message with the human-readable error description, and other attributes specific for the error code.

Examples:

To call customer_add function from vshard/example, say:

vshard.router.call(100,
                   'write',
                   'customer_add',
                   {{customer_id = 2, bucket_id = 100, name = 'name2', accounts = {}}},
                   {timeout = 5})
-- or, the same thing but with a map for the second argument
vshard.router.call(100,
                   {mode='write'},
                   'customer_add',
                   {{customer_id = 2, bucket_id = 100, name = 'name2', accounts = {}}},
                   {timeout = 5})
vshard.router.callro(bucket_id, function_name, {argument_list}, {options})

Call the function identified by function-name on the shard storing the bucket identified by bucket_id, in read-only mode (similar to calling vshard.router.call with mode=“read“). See the Processing requests section for details on function operation.

Параметры:
  • bucket_id – a bucket identifier
  • function_name – a function to execute
  • argument_list – an array of the function’s arguments
  • options –
    • timeout — a request timeout, in seconds.If the router cannot identify a shard with the specified bucket_id, it will retry until the timeout is reached.
    • other net.box options, such as is_async, buffer, on_push are also supported.
Return:

The original return value of the executed function, or nil and error object. The error object has a type attribute equal to ShardingError or one of the regular Tarantool errors (ClientError, OutOfMemory, SocketError, etc.).

ShardingError is returned on errors specific for sharding: the replica set is not available, the master is missing, wrong bucket id, etc. It has an attribute code containing one of the values from the vshard.error.code.* LUA table, an optional attribute containing a message with the human-readable error description, and other attributes specific for this error code.

vshard.router.callrw(bucket_id, function_name, {argument_list}, {options})

Call the function identified by function-name on the shard storing the bucket identified by bucket_id, in read-write mode (similar to calling vshard.router.call with mode=“write“). See the Processing requests section for details on function operation.

Параметры:
  • bucket_id – a bucket identifier
  • function_name – a function to execute
  • argument_list – an array of the function’s arguments
  • options –
    • timeout — a request timeout, in seconds. If the router cannot identify a shard with the specified bucket_id, it will retry until the timeout is reached.
    • other net.box options, such as is_async, buffer, on_push are also supported.
Return:

The original return value of the executed function, or nil and error object. The error object has a type attribute equal to ShardingError or one of the regular Tarantool errors (ClientError, OutOfMemory, SocketError, etc.).

ShardingError is returned on errors specific for sharding: the replica set is not available, the master is missing, wrong bucket id, etc. It has an attribute code containing one of the values from the vshard.error.code.* LUA table, an optional attribute containing a message with the human-readable error description, and other attributes specific for this error code.

vshard.router.callre(bucket_id, function_name, {argument_list}, {options})

Call the function identified by function-name on the shard storing the bucket identified by bucket_id, in read-only mode (similar to calling vshard.router.call with mode='read'), with preference for a replica rather than a master (similar to calling vshard.router.call with prefer_replica = true). See the Processing requests section for details on function operation.

Параметры:
  • bucket_id – a bucket identifier
  • function_name – a function to execute
  • argument_list – an array of the function’s arguments
  • options –
    • timeout — a request timeout, in seconds. If the router cannot identify a shard with the specified bucket_id, it will retry until the timeout is reached.
    • other net.box options, such as is_async, buffer, on_push are also supported.
Return:

The original return value of the executed function, or nil and error object. The error object has a type attribute equal to ShardingError or one of the regular Tarantool errors (ClientError, OutOfMemory, SocketError, etc.).

ShardingError is returned on errors specific for sharding: the replica set is not available, the master is missing, wrong bucket id, etc. It has an attribute code containing one of the values from the vshard.error.code.* LUA table, an optional attribute containing a message with the human-readable error description, and other attributes specific for this error code.

vshard.router.callbro(bucket_id, function_name, {argument_list}, {options})

This has the same effect as vshard.router.call() with mode parameter = {mode='read', balance=true}.

vshard.router.callbre(bucket_id, function_name, {argument_list}, {options})

This has the same effect as vshard.router.call() with mode parameter = {mode='read', balance=true, prefer_replica=true}.

vshard.router.map_callrw(function_name, {argument_list}, {options})

The function implements consistent map-reduce over the entire cluster. Consistency means:

  • All the data was accessible.
  • The data was not migrated between physical storages during the map requests execution.

The function can be helpful if you need to access:

  • all the data in the cluster
  • a vast number of buckets scattered over the instances in case their individual vshard.router.call() takes up too much time.

The function is called on the master node of each replica set with the given arguments.

Параметры:
  • function_name – a function to call on the storages (masters of all replica sets)
  • argument_list – an array of the function’s arguments
  • options –
    • timeout – a request timeout, in seconds. The timeout is for the entire map_callrw(), including all its stages.
    • return_raw – the net.box option implemented in Tarantool since version 2.10.0. If set to true, net.box returns the response data wrapped in a MessagePack object instead of decoding it to Lua. For more details, see the Return section below.

Важно

Do not use a big timeout (longer than 1 minute, for instance). The router tries to block the bucket moves to another storage for the given timeout on all storages. On failure, the block remains for the entire timeout.

Return:

  • On success: a map with replica set UUIDs (keys) and results of the function_name (values).

    {uuid1 = {res1}, uuid2 = {res2}, ...}

    If the function returns nil or box.NULL from one of the storages, it will not be present in the resulting map.

    If the return_raw option is used, the result is a map of the following format: {[replicaset_uuid] = msgpack.object} where msgpack.object is an object that stores a MessagePack array with the results returned from the storage map function.

    The option use case is the same as in using net.box: to avoid decoding of the call results into Lua. The option can be helpful if a router is used as a proxy and results received from a storage are big.

    Example:

    local res = vshard.router.map_callrw('my_func', args, {..., return_raw = true})

for replicaset_uuid, msgpack_value in pairs(res) do
    log.info('Replicaset %s returned %s', replicaset_uuid,
             msgpack_value:decode())
end

    This is an illustration of the option usage. Normally, you don’t need to use return_raw if you call the decode() function.

  • On failure: nil, error object, and optional replica set UUID where the error occurred. UUID will not be returned if the error is not related to a particular replica set. For instance, the method fails if not all buckets were found, even if all replica sets were scanned successfully. Handling the result looks like this:

    res, err, uuid = vshard.router.map_callrw(...)
if not res then
    -- Error.
    -- 'err' - error object. 'uuid' - optional UUID of replica set
    -- where the error happened.
    ...
else
    -- Success.
    for uuid, value in pairs(res) do
        ...
    end
end

    If the return_raw option is used, the result on failure is the same as described above.

Map-Reduce in vshard can be divided into three stages: Ref, Map, and Reduce.

Ref and Map. map_callrw() combines both the Ref and the Map stages. The Ref stage ensures data consistency while executing the user’s function (function_name) on all nodes. Keep in mind that consistency is incompatible with rebalancing (it breaks data consistency). Map-reduce and rebalancing are mutually exclusive, they compete for the cluster time. Any bucket move makes the sender and receiver nodes inconsistent, so it is impossible to call a function on them to access all the data without vshard.storage.bucket_ref(). It makes the Ref stage intricate, as it should work together with the rebalancer to ensure they do not block each other.

For this, the storage has a special scheduler for bucket moves and storage refs. Storage ref is a volatile counter defined on each instance. It is incremented when a map-reduce request comes and decremented when it ends. Storage ref pins the entire instance with all its buckets, not just a single bucket (like bucket ref).

The scheduler shares storage time between bucket moves and storage refs fairly. The distribution depends on how long and frequent the moves and refs are. It can be configured using the storage options sched_move_quota and sched_ref_quota. Keep in mind that the scheduler configuration may affect map-reduce requests if used during rebalancing.

During the Map stage, map_callrw() sends map requests one by one to many servers. On success, the function returns a map. The map is a set of «key—value» pairs. The keys are replica set UUIDs, and the values are the results of the user’s function—function_name.

Reduce. The Reduce stage is not performed by vshard. It is what the user’s code does with the results of map_callrw().

Примечание

map_callrw() works only on masters. Therefore, you can’t use it if at least one replica set has its master node down.

vshard.router.route(bucket_id)

Return the replica set object for the bucket with the specified bucket id value.

Параметры:
  • bucket_id – a bucket identifier
Return:

a replica set object

Example:

replicaset = vshard.router.route(123)
vshard.router.routeall()

Return all available replica set objects.

Return:a map of the following type: {UUID = replicaset}
Rtype:a map of replica set objects

Example:

function selectall()
    local resultset = {}
    shards, err = vshard.router.routeall()
    if err ~= nil then
        error(err)
    end
    for uid, replica in pairs(shards) do
        local set = replica:callro('box.space.*space-name*:select', {{}, {limit=10}}, {timeout=5})
        for _, item in ipairs(set) do
            table.insert(resultset, item)
        end
    end
    table.sort(resultset, function(a, b) return a[1] < b[1] end)
    return resultset
end
vshard.router.bucket_id(key)

Deprecated. Logs a warning when used because it is not consistent for cdata numbers.

In particular, it returns 3 different values for normal Lua numbers like 123, for unsigned long long cdata (like 123ULL, or ffi.cast('unsigned long long',123)), and for signed long long cdata (like 123LL, or ffi.cast('long long', 123)). And it is important.

vshard.router.bucket_id(123)
vshard.router.bucket_id(123LL)
vshard.router.bucket_id(123ULL)

For float and double cdata (ffi.cast('float', number), ffi.cast('double', number)) these functions return different values even for the same numbers of the same floating point type. This is because tostring() on a floating point cdata number returns not the number, but a pointer at it. Different on each call.

vshard.router.bucket_id_strcrc32() behaves exactly the same, but does not log a warning. In case you need that behavior.

vshard.router.bucket_id_strcrc32(key)

Calculate the bucket id using a simple built-in hash function.

Параметры:
  • key – a hash key. This can be any Lua object (number, table, string).
Return:

a bucket identifier
Rtype:

number

Example:

tarantool> vshard.router.bucket_count()
---
- 3000
...

tarantool> vshard.router.bucket_id_strcrc32("18374927634039")
---
- 2032
...

tarantool> vshard.router.bucket_id_strcrc32(18374927634039)
---
- 2032
...

tarantool> vshard.router.bucket_id_strcrc32("test")
---
- 1216
...

tarantool> vshard.router.bucket_id_strcrc32("other")
---
- 2284
...

Примечание

Remember that it is not safe. See details in bucket_id()

vshard.router.bucket_id_mpcrc32(key)

This function is safer than bucket_id_strcrc32. It takes a CRC32 from a MessagePack encoded value. That is, bucket id of integers does not depend on their Lua type. In case of a string key, it does not encode it into MessagePack, but takes a hash right from the string.

Параметры:
  • key – a hash key. This can be any Lua object (number, table, string).
Return:

a bucket identifier
Rtype:

number

However it still may return different values for not equal floating point types. That is, ffi.cast('float', number) may be reflected into a bucket id not equal to ffi.cast('double', number). This can’t be fixed, because a float value, even being casted to double, may have a garbage tail in its fraction.

Floating point keys should not be used to calculate a bucket id, usually.

Be very careful in case you store floating point types in a space. When data is returned from a space, it is cast to Lua number. And if that value had an empty fraction part, it will be treated as an integer by bucket_id_mpcrc32(). So you need to do explicit casts in such cases. Here is an example of the problem:

tarantool> s = box.schema.create_space('test', {format = {{'id', 'double'}}}); _ = s:create_index('pk')
---
...

tarantool> inserted = ffi.cast('double', 1)
---
...

-- Value is stored as double
tarantool> s:replace({inserted})
---
- [1]
...

-- But when returned to Lua, stored as Lua number, not cdata.
tarantool> returned = s:get({inserted}).id
---
...

tarantool> type(returned), returned
---
- number
- 1
...

tarantool> vshard.router.bucket_id_mpcrc32(inserted)
---
- 1411
...
tarantool> vshard.router.bucket_id_mpcrc32(returned)
---
- 1614
...
vshard.router.bucket_count()

Return the total number of buckets specified in vshard.router.cfg().

Return:the total number of buckets
Rtype:number 
tarantool> vshard.router.bucket_count()
---
- 10000
...
vshard.router.sync(timeout)

Wait until the dataset is synchronized on replicas.

Параметры:
  • timeout – a timeout, in seconds
Return:

true if the dataset was synchronized successfully; or nil and err explaining why the dataset cannot be synchronized.
vshard.router.discovery_wakeup()

Force wakeup of the bucket discovery fiber.

vshard.router.discovery_set(mode)

Turn on/off the background discovery fiber used by the router to find buckets.

Параметры:
  • mode – working mode of a discovery fiber. There are three modes: on, off and once

When the mode is on (default), the discovery fiber works during all the lifetime of the router. Even after all buckets are discovered, it will still come to storages and download their buckets with some big period (DISCOVERY_IDLE_INTERVAL). This is useful if the bucket topology changes often and the number of buckets is not big. The router will keep its route table up to date even when no requests are processed.

When the mode is off, discovery is disabled completely.

When the mode is once, discovery starts and finds the locations of all buckets, and then the discovery fiber is terminated. This is good for a large bucket count and for clusters, where rebalancing is rare.

The method is good to enable/disable discovery after the router is already started, but discovery is enabled by default. You may want to never enable it even for a short time—then specify the discovery_mode option in the configuration. It takes the same values as vshard.router.discovery_set(mode).

You may decide to turn off discovery or make it once if you have many routers, or tons of buckets (hundreds of thousands and more), and you see that the discovery process consumes notable CPU % on routers and storages. In that case it may be wise to turn off the discovery when there is no rebalancing in the cluster. And turn it on for new routers, as well as for all routers when rebalancing is started.

vshard.router.info({options})

Return information about each instance. Since vshard v.0.1.22, the function also accepts options, which can be used to get additional information.

Параметры:
  • options –
    • with_services — a bool value. If set to true, the function returns information about the background services (such as discovery, master search, or failover) that are working on the current instance.
Return:

Replica set parameters:

  • replica set uuid
  • master instance parameters
  • replica instance parameters

Instance parameters:

  • uri—URI of the instance
  • uuid—UUID of the instance
  • status—status of the instance (available, unreachable, missing)
  • network_timeout—a timeout for the request. The value is updated automatically on each 10th successful request and each 2nd failed request.

Bucket parameters:

  • available_ro – the number of buckets known to the router and available for read requests
  • available_rw – the number of buckets known to the router and available for read and write requests
  • unreachable – the number of buckets known to the router but unavailable for any requests
  • unknown – the number of buckets whose replica sets are not known to the router

Service parameters:

  • name – service name. Possible values: discovery, failover, master_search.
  • status – service status. Possible values: ok, error.
  • error – error message that appears on the error status.
  • activity – service state. It shows what the service is currently doing (for example, updating replicas).
  • status_idx – incrementing counter of the status changes. The ok status is updated on every successful iteration of the service. The error status is updated only when it is fixed.

Example:

tarantool> vshard.router.info()
---
- replicasets:
    ac522f65-aa94-4134-9f64-51ee384f1a54:
      replica: &0
        network_timeout: 0.5
        status: available
        uri: storage@127.0.0.1:3303
        uuid: 1e02ae8a-afc0-4e91-ba34-843a356b8ed7
      uuid: ac522f65-aa94-4134-9f64-51ee384f1a54
      master: *0
    cbf06940-0790-498b-948d-042b62cf3d29:
      replica: &1
        network_timeout: 0.5
        status: available
        uri: storage@127.0.0.1:3301
        uuid: 8a274925-a26d-47fc-9e1b-af88ce939412
      uuid: cbf06940-0790-498b-948d-042b62cf3d29
      master: *1
  bucket:
    unreachable: 0
    available_ro: 0
    unknown: 0
    available_rw: 3000
  status: 0
  alerts: []
...

tarantool> vshard.router.info({with_services = true})
---
<all info from vshard.router.info()>
  services:
    failover:
      status_idx: 2
      error:
      activity: idling
      name: failover
      status: ok
    discovery:
      status_idx: 2
      error: Error during discovery: TimedOut
      activity: idling
      name: discovery
      status: error
...
vshard.router.buckets_info()

Return information about each bucket. Since a bucket map can be huge, only the required range of buckets can be specified.

Параметры:
  • offset – the offset in a bucket map of the first bucket to show
  • limit – the maximum number of buckets to show
Return:

a map of the following type: {bucket_id = 'unknown'/replicaset_uuid}

 
tarantool> vshard.router.buckets_info()
---
- - uuid: aaaaaaaa-0000-4000-a000-000000000000
    status: available_rw
  - uuid: aaaaaaaa-0000-4000-a000-000000000000
    status: available_rw
  - uuid: aaaaaaaa-0000-4000-a000-000000000000
    status: available_rw
  - uuid: bbbbbbbb-0000-4000-a000-000000000000
    status: available_rw
  - uuid: bbbbbbbb-0000-4000-a000-000000000000
    status: available_rw
  - uuid: bbbbbbbb-0000-4000-a000-000000000000
    status: available_rw
  - uuid: bbbbbbbb-0000-4000-a000-000000000000
    status: available_rw
...
vshard.router.enable()

Since vshard v.0.1.21. Manually allow access to the router API, revert vshard.router.disable().

Примечание

vshard.router.enable() cannot be used for enabling a router API that was automatically disabled due to a running configuration process.

vshard.router.disable()

Since vshard v.0.1.21. Manually restrict access to the router API. When the API is disabled, all its methods throw a Lua error, except vshard.router.cfg(), vshard.router.new(), vshard.router.enable() and vshard.router.disable(). The error object’s name attribute is ROUTER_IS_DISABLED.

The router is enabled by default. However, it is automatically and forcefully disabled until the configuration is finished, as accessing the router’s methods at that time is not safe.

Manual disabling can be used, for example, if some preparatory work needs to be done after calling vshard.router.cfg() but before the router’s methods are available. It will look like this:

vshard.router.disable()
vshard.router.cfg(...)
-- Some preparatory work here ...
vshard.router.enable()
-- vshard.router's methods are available now
object replicaset_object
replicaset_object:call(function_name, {argument_list}, {options})

Call a function on a nearest available master (distances are defined using replica.zone and cfg.weights matrix) with specified arguments.

Примечание

The replicaset_object:call method is similar to replicaset_object:callrw.

Параметры:
  • function_name – function to execute
  • argument_list – array of the function’s arguments
  • options –
    • timeout — a request timeout, in seconds. If the router cannot identify a shard with the specified bucket_id, it will retry until the timeout is reached.
    • other net.box options, such as is_async, buffer, on_push are also supported.
Return:
  • result of function_name on success
  • nil, err otherwise
replicaset_object:callrw(function_name, {argument_list}, {options})

Call a function on a nearest available master (distances are defined using replica.zone and cfg.weights matrix) with a specified arguments.

Примечание

The replicaset_object:callrw method is similar to replicaset_object:call.

Параметры:
  • function_name – function to execute
  • argument_list – array of the function’s arguments
  • options –
    • timeout — a request timeout, in seconds. If the router cannot identify a shard with the specified bucket_id, it will retry until the timeout is reached.
    • other net.box options, such as is_async, buffer, on_push are also supported.
Return:
  • result of function_name on success
  • nil, err otherwise
 
tarantool> local bucket = 1; return vshard.router.callrw(
         >     bucket,
         >     'box.space.actors:insert',
         >     {{
         >         1, bucket, 'Renata Litvinova',
         >         {theatre="Moscow Art Theatre"}
         >     }},
         >     {timeout=5}
         > )
replicaset_object:callro(function_name, {argument_list}, {options})

Call a function on the nearest available replica (distances are defined using replica.zone and cfg.weights matrix) with specified arguments. It is recommended to use replicaset_object:callro() for calling only read-only functions, as the called functions can be executed not only on a master, but also on replicas.

Параметры:
  • function_name – function to execute
  • argument_list – array of the function’s arguments
  • options –
    • timeout — a request timeout, in seconds. If the router cannot identify a shard with the specified bucket_id, it will retry until the timeout is reached.
    • other net.box options, such as is_async, buffer, on_push are also supported.
Return:
  • result of function_name on success
  • nil, err otherwise
replicaset:callre(function_name, {argument_list}, {options})

Call a function on the nearest available replica (distances are defined using replica.zone and cfg.weights matrix) with specified arguments, with preference for a replica rather than a master (similar to calling vshard.router.call with prefer_replica = true). It is recommended to use replicaset_object:callre() for calling only read-only functions, as the called function can be executed not only on a master, but also on replicas.

Параметры:
  • function_name – function to execute
  • argument_list – array of the function’s arguments
  • options –
    • timeout — a request timeout, in seconds. If the router cannot identify a shard with the specified bucket_id, it will retry until the timeout is reached.
    • other net.box options, such as is_async, buffer, on_push are also supported.
Return:
  • result of function_name on success
  • nil, err otherwise
vshard.router.master_search_wakeup()

Automated master discovery works in its own fiber on a router, which is activated only if at least one replica set is configured to look for the master (the master parameter is set to auto). The fiber wakes up within a certain period. But it is possible to wake it up on demand by using this function.

Manual fiber wakeup can help speed up tests for master change. Another use case is performing some actions with a router in the router console.

The function does nothing if master search is not configured for any replica set.

Return:none

Router internal API

vshard.router.bucket_discovery(bucket_id)

Search for the bucket in the whole cluster. If the bucket is not found, it is likely that it does not exist. The bucket might also be moved during rebalancing and currently is in the RECEIVING state.

Параметры:
  • bucket_id – a bucket identifier

Storage API

Storage public API
Storage internal API

Storage public API

vshard.storage.cfg(cfg, instance_uuid)

Configure the database and start sharding for the specified storage instance.

Параметры:
  • cfg – a storage configuration
  • instance_uuid – UUID of the instance
vshard.storage.info({options})

Return information about the storage instance. Since vshard v.0.1.22, the function also accepts options, which can be used to get additional information.

Параметры:
  • options –
    • with_services — a bool value. If set to true, the function returns information about the background services (such as garbage collector, rebalancer, recovery, or applier of the routes) that are working on the current instance. See vshard.router.info for detailed reference.

Example:

tarantool> vshard.storage.info()
---
- replicasets:
    c862545d-d966-45ff-93ad-763dce4a9723:
      uuid: c862545d-d966-45ff-93ad-763dce4a9723
      master:
        uri: admin@localhost:3302
    1990be71-f06e-4d9a-bcf9-4514c4e0c889:
      uuid: 1990be71-f06e-4d9a-bcf9-4514c4e0c889
      master:
        uri: admin@localhost:3304
  bucket:
    receiving: 0
    active: 15000
    total: 15000
    garbage: 0
    pinned: 0
    sending: 0
  status: 0
  replication:
    status: master
  alerts: []
...
vshard.storage.call(bucket_id, mode, function_name, {argument_list})

Call the specified function on the current storage instance.

Параметры:
  • bucket_id – a bucket identifier
  • mode – a type of the function: „read“ or „write“
  • function_name – function to execute
  • argument_list – array of the function’s arguments
Return:

The original return value of the executed function, or nil and error object.

vshard.storage.sync(timeout)

Wait until the dataset is synchronized on replicas.

Параметры:
  • timeout – a timeout, in seconds
Return:

true if the dataset was synchronized successfully; or nil and err explaining why the dataset cannot be synchronized.
vshard.storage.bucket_pin(bucket_id)

Pin a bucket to a replica set. A pinned bucket cannot be moved even if it breaks the cluster balance.

Параметры:
  • bucket_id – a bucket identifier
Return:

true if the bucket is pinned successfully; or nil and err explaining why the bucket cannot be pinned
vshard.storage.bucket_unpin(bucket_id)

Return a pinned bucket back into the active state.

Параметры:
  • bucket_id – a bucket identifier
Return:

true if the bucket is unpinned successfully; or nil and err explaining why the bucket cannot be unpinned
vshard.storage.bucket_ref(bucket_id, mode)

Create an RO or RW ref.

Параметры:
  • bucket_id – a bucket identifier
  • mode – „read“ or „write“
Return:

true if the bucket ref is created successfully; or nil and err explaining why the ref cannot be created
vshard.storage.bucket_refro(bucket_id)

An alias for vshard.storage.bucket_ref in the RO mode.

Параметры:
  • bucket_id – a bucket identifier
Return:

true if the bucket ref is created successfully; or nil and err explaining why the ref cannot be created
vshard.storage.bucket_refrw(bucket_id)

An alias for vshard.storage.bucket_ref in the RW mode.

Параметры:
  • bucket_id – a bucket identifier
Return:

true if the bucket ref is created successfully; or nil and err explaining why the ref cannot be created
vshard.storage.bucket_unref(bucket_id, mode)

Remove a RO/RW ref.

Параметры:
  • bucket_id – a bucket identifier
  • mode – „read“ or „write“
Return:

true if the bucket ref is removed successfully; or nil and err explaining why the ref cannot be removed
vshard.storage.bucket_unrefro(bucket_id)

An alias for vshard.storage.bucket_unref in the RO mode.

Параметры:
  • bucket_id – a bucket identifier
Return:

true if the bucket ref is removed successfully; or nil and err explaining why the ref cannot be removed
vshard.storage.bucket_unrefrw(bucket_id)

An alias for vshard.storage.bucket_unref in the RW mode.

Параметры:
  • bucket_id – a bucket identifier
Return:

true if the bucket ref is removed successfully; or nil and err explaining why the ref cannot be removed
vshard.storage.find_garbage_bucket(bucket_index, control)

Find a bucket which has data in a space but is not stored in a _bucket space; or is in a GARBAGE state.

Параметры:
  • bucket_index – index of a space with the part of a bucket id
  • control – a garbage collector controller. If there is an increased buckets generation, then the search should be interrupted.
Return:

an identifier of the bucket in the garbage state, if found; otherwise, nil
vshard.storage.buckets_info()

Return information about each bucket located in storage. For example:

tarantool> vshard.storage.buckets_info(1)
---
- 1:
    status: active
    ref_rw: 1
    ref_ro: 1
    ro_lock: true
    rw_lock: true
    id: 1
vshard.storage.buckets_count()

Return the number of buckets located in storage.

vshard.storage.recovery_wakeup()

Immediately wake up a recovery fiber, if it exists.

vshard.storage.rebalancing_is_in_progress()

Return a flag indicating whether rebalancing is in progress. The result is true if the node is currently applying routes received from a rebalancer node in the special fiber.

vshard.storage.is_locked()

Return a flag indicating whether storage is invisible to the rebalancer.

vshard.storage.rebalancer_disable()

Disable rebalancing. A disabled rebalancer sleeps until it is enabled again with vshard.storage.rebalancer_enable().

vshard.storage.rebalancer_enable()

Enable rebalancing.

vshard.storage.sharded_spaces()

Show the spaces that are visible to rebalancer and garbage collector fibers.

tarantool> vshard.storage.sharded_spaces()
---
- 513:
    engine: memtx
    before_replace: 'function: 0x010e50e738'
    field_count: 0
    id: 513
    on_replace: 'function: 0x010e50e700'
    temporary: false
    index:
      0: &0
        unique: true
        parts:
        - type: number
          fieldno: 1
          is_nullable: false
        id: 0
        type: TREE
        name: primary
        space_id: 513
      1: &1
        unique: false
        parts:
        - type: number
          fieldno: 2
          is_nullable: false
        id: 1
        type: TREE
        name: bucket_id
        space_id: 513
      primary: *0
      bucket_id: *1
    is_local: false
    enabled: true
    name: actors
    ck_constraint: []
...
vshard.storage.on_bucket_event([trigger-function[, old-trigger-function]])

Since vshard v.0.1.22. Define a trigger for execution when the data from the user spaces is changed (deleted or inserted) due to the rebalancing process. The trigger is invoked each time the data batch changes.

Параметры:
  • trigger-function (function) – function which will become the trigger function.
  • old-trigger-function (function) – existing trigger function which will be replaced by trigger-function.
Return:

nil or function pointer

The trigger-function can have up to three parameters:

  • event_type (string) – in order to distinguish event, you can compare this argument with the supported event types, bucket_data_recv_txn and bucket_data_gc_txn.
  • bucket_id (unsigned) – bucket id.
  • data (table) – additional information about data change transaction. Currently it only includes an array of all spaces (data.spaces), affected by a transaction in which trigger-function is executed.

Example:

vshard.storage.on_bucket_event(function(event, bucket_id, data)
    if event == 'bucket_data_recv_txn' then
        -- Handle it.
        for idx, space in ipairs(data.spaces) do
            ...
        end
    elseif event == 'bucket_data_gc_txn' then
        -- Handle it.
        ...
    end
end)

Примечание

As everything executed inside triggers is already in a transaction, you shouldn’t use transactions, yield-operations (explicit or not), changes to different space engines (see rule #2).

If the parameters are (nil, old-trigger-function), then the old trigger is deleted. If both parameters are omitted, then the response is a list of existing trigger functions.

Details about trigger characteristics are in the triggers section.

Storage internal API

vshard.storage.bucket_recv(bucket_id, from, data)

Receive a bucket identified by bucket id from a remote replica set.

Параметры:
  • bucket_id – a bucket identifier
  • from – UUID of source replica set
  • data – data logically stored in a bucket identified by bucket_id, in the same format as the return value from bucket_collect() <storage_api-bucket_collect>
vshard.storage.bucket_stat(bucket_id)

Return information about the bucket id:

tarantool> vshard.storage.bucket_stat(1)
---
- 0
- status: active
  id: 1
...
Параметры:
  • bucket_id – a bucket identifier
vshard.storage.bucket_delete_garbage(bucket_id)

Force garbage collection for the bucket identified by bucket_id in case the bucket was transferred to a different replica set.

Параметры:
  • bucket_id – a bucket identifier
vshard.storage.bucket_collect(bucket_id)

Collect all the data that is logically stored in the bucket identified by bucket_id:

tarantool> vshard.storage.bucket_collect(1)
---
- 0
- - - 514
    - - [10, 1, 1, 100, 'Account 10']
      - [11, 1, 1, 100, 'Account 11']
      - [12, 1, 1, 100, 'Account 12']
      - [50, 5, 1, 100, 'Account 50']
      - [51, 5, 1, 100, 'Account 51']
      - [52, 5, 1, 100, 'Account 52']
  - - 513
    - - [1, 1, 'Customer 1']
      - [5, 1, 'Customer 5']
...
Параметры:
  • bucket_id – a bucket identifier
vshard.storage.bucket_force_create(first_bucket_id, count)

Force creation of the buckets (single or multiple) on the current replica set. Use only for manual emergency recovery or for initial bootstrap.

Параметры:
  • first_bucket_id – an identifier of the first bucket in a range
  • count – the number of buckets to insert (default = 1)
vshard.storage.bucket_force_drop(bucket_id)

Drop a bucket manually for tests or emergency cases.

Параметры:
  • bucket_id – a bucket identifier
vshard.storage.bucket_send(bucket_id, to)

Send a specified bucket from the current replica set to a remote replica set.

Параметры:
  • bucket_id – bucket identifier
  • to – UUID of a remote replica set
vshard.storage.rebalancer_request_state()

Check all buckets of the host storage that have the SENT or ACTIVE state, return the number of active buckets.

Return:the number of buckets in the active state, if found; otherwise, nil
vshard.storage.buckets_discovery()

Collect an array of active bucket identifiers for discovery.

Модули СУБД SQL

В данном разделе справочника рассматривается внедрение и использование двух уже созданных модулей: сторонние библиотеки СУБД SQL для MySQL и PostgreSQL.

Для вызова другой СУБД из Tarantool нужно: другая СУБД и Tarantool. Модуль, который соединяет другую СУБД может называться коннектором. В модуле есть библиотека общего пользования, которая может называться драйвером.

Tarantool предоставляет модули-коннекторы для СУБД вместе с менеджером модулей для Lua под названием LuaRocks.

Модули Tarantool позволяют подключаться к SQL-серверам и выполнять SQL-запросы так же, как это делает клиент MySQL или PostgreSQL. Операторы SQL доступны как Lua-методы. Таким образом, Tarantool может служить Lua-коннектором для MySQL или Lua-коннектором для PostgreSQL, что было бы полезно, даже если бы Tarantool больше ничего не умел. Но конечно же, Tarantool также представляет собой СУБД, поэтому модуль используется для любых операций, таких как копирование и ускорение базы данных, которые максимально эффективно, если приложение может работать как с SQL, так и с Tarantool в пределах одной Lua-процедуры. Методы подключения / выборки / вставки / и т.д. аналогичны методам модуля net.box.

С точки зрения пользователя, модули для MySQL и PostgreSQL очень похожи, поэтому следующие разделы – «Пример для MySQL» и «Пример для PostgreSQL» – слегка избыточны.

Пример для MySQL

В данном примере предполагается, что установлены MySQL 5.5, MySQL 5.6 или MySQL 5.7. Последние версии MariaDB также подойдут, используется коннектор к MariaDB для C. Самым важным пакетом будет пакет для разработчиков клиента MySQL, который обычно называется libmysqlclient-dev. Наиболее важным файлом из этого пакета будет файл libmysqlclient.so или с похожим названием. Можно использовать `` find`` или `` whereis``, чтобы узнать, в каких директориях установлены эти файлы.

Также нужно будет установить библиотеку общего пользования Tarantool с драйвером для MySQL, загрузить ее и использовать для подключения к экземпляру MySQL-сервера. После этого можно передавать любой оператор MySQL на экземпляр сервера и получать результаты, включая наборы результатов.

Установка

Проверьте инструкции по загрузке и установке бинарного пакета, которые применимы к среде, где установлен Tarantool. Помимо установки tarantool, установите tarantool-dev. Например, в Ubuntu добавьте строку:

$ sudo apt-get install tarantool-dev

Что касается библиотеки общего пользования с драйвером для MySQL, ее можно установить двумя способами:

Из LuaRocks

Begin by installing luarocks and making sure that tarantool is among the upstream servers, as in the instructions on rocks.tarantool.org, the Tarantool luarocks page. Now execute this:

luarocks install mysql [MYSQL_LIBDIR = path]
                       [MYSQL_INCDIR = path]
                       [--local]

Пример:

$ luarocks install mysql MYSQL_LIBDIR=/usr/local/mysql/lib

Из GitHub

Go the site github.com/tarantool/mysql. Follow the instructions there, saying:

$ git clone https://github.com/tarantool/mysql.git
 $ cd mysql && cmake . -DCMAKE_BUILD_TYPE=RelWithDebInfo
 $ make
 $ make install

На данном этапе желательно проверить, что после установки появился файл под названием driver.so, а также проверить, что этот файл находится в директории, которую можно найти по запросу require.

Подключение

Начните с выполнения запроса require для драйвера mysql. В дальнейших примерах у него будет имя mysql.

mysql = require('mysql')

Теперь выполните:

*имя_подключения* = mysql.connect(*параметры подключения*)

Параметры подключения включены в таблицу. Доступные параметры:

  • host = имя-хоста – строка, значение по умолчанию = „localhost“
  • port = номер-порта – число, значение по умолчанию = 3306
  • user = имя-пользователя – строка, значение по умолчанию – имя пользователя в операционной системе
  • password = пароль – строка, по умолчанию пустая
  • db = имя-базы-данных – строка, по умолчанию пустая
  • raise = true|false – логическое значение, по умолчанию, false (ложь)

The option names, except for raise, are similar to the names that MySQL’s mysql client uses, for details see the MySQL manual at dev.mysql.com/doc/refman/5.6/en/connecting.html. The raise option should be set to true if errors should be raised when encountered. To connect with a Unix socket rather than with TCP, specify host = 'unix/' and port = socket-name.

Пример с использованием таблицы, заключенной в {фигурные скобки}:

conn = mysql.connect({
     host = '127.0.0.1',
     port = 3306,
     user = 'p',
     password = 'p',
     db = 'test',
     raise = true
 })
-- ИЛИ
conn = mysql.connect({
    host = 'unix/',
    port = '/var/run/mysqld/mysqld.sock'
})

Пример с созданием функции, которая определяет параметры в отдельных строках:

tarantool> -- Функция подключения. Использование: conn = mysql_connect()
tarantool> function mysql_connection()
         >   local p = {}
         >   p.host = 'widgets.com'
         >   p.db = 'test'
         >   conn = mysql.connect(p)
         >   return conn
         > end
---
...
tarantool> conn = mysql_connect()
---
...

Предполагаем, что в дальнейших примерах будет использоваться имя „conn“.

Как проверить связь

Чтобы убедиться, что подключение работает, следует использовать запрос:

*имя-соединение*:ping()

Пример:

tarantool> conn:ping()
---
- true
...

Исполнение оператора

Для всех операторов MySQL запрос будет:

*имя-соединения*:execute(*sql-оператор* [, *параметры*])

где sql-statement – это строка, а необязательные параметры – это дополнительные значения, которыми можно заменить любые знаки вопроса («?») в SQL-операторе.

Пример:

tarantool> conn:execute('select table_name from information_schema.tables')
---
- - table_name: ALL_PLUGINS
  - table_name: APPLICABLE_ROLES
  - table_name: CHARACTER_SETS
  <...>
- 78
...

Закрытие соединения

Чтобы закрыть сессию, которую открыли с помощью mysql.connect, используется следующий запрос:

*имя-соединения*:close()

Пример:

tarantool> conn:close()
---
...

For further information, including examples of rarely-used requests, see the README.md file at github.com/tarantool/mysql.

Пример

Пример выполняется на машине с ОС Ubuntu 12.04 (Precise Pangolin), где Tarantool установлен в поддиректорию /usr, а копия MySQL установлена в ~/mysql-5.5. Экземпляр сервера mysqld уже запущен на localhost 127.0.0.1.

$ export TMDIR=~/mysql-5.5
$ # Check that the include subdirectory exists by looking
$ # for .../include/mysql.h. (If this fails, there's a chance
$ # that it's in .../include/mysql/mysql.h instead.)
$ [ -f $TMDIR/include/mysql.h ] && echo "OK" || echo "Error"
OK

$ # Check that the library subdirectory exists and has the
$ # necessary .so file.
$ [ -f $TMDIR/lib/libmysqlclient.so ] && echo "OK" || echo "Error"
OK

$ # Check that the mysql client can connect using some factory
$ # defaults: port = 3306, user = 'root', user password = '',
$ # database = 'test'. These can be changed, provided one uses
$ # the changed values in all places.
$ $TMDIR/bin/mysql --port=3306 -h 127.0.0.1 --user=root \
    --password= --database=test
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 25
Server version: 5.5.35 MySQL Community Server (GPL)
...
Type 'help;' or '\h' for help. Type '\c' to clear ...

$ # Insert a row in database test, and quit.
mysql> CREATE TABLE IF NOT EXISTS test (s1 INT, s2 VARCHAR(50));
Query OK, 0 rows affected (0.13 sec)
mysql> INSERT INTO test.test VALUES (1,'MySQL row');
Query OK, 1 row affected (0.02 sec)
mysql> QUIT
Bye

$ # Install luarocks
$ sudo apt-get -y install luarocks | grep -E "Setting up|already"
Setting up luarocks (2.0.8-2) ...

$ # Set up the Tarantool rock list in ~/.luarocks,
$ # following instructions at rocks.tarantool.org
$ mkdir ~/.luarocks
$ echo "rocks_servers = {[[http://rocks.tarantool.org/]]}" >> \
    ~/.luarocks/config.lua

$ # Ensure that the next "install" will get files from Tarantool
$ # master repository. The resultant display is normal for Ubuntu
$ # 12.04 precise
$ cat /etc/apt/sources.list.d/tarantool.list
deb http://tarantool.org/dist/2.1/ubuntu/ precise main
deb-src http://tarantool.org/dist/2.1/ubuntu/ precise main

$ # Install tarantool-dev. The displayed line should show version = 2.1
$ sudo apt-get -y install tarantool-dev | grep -E "Setting up|already"
Setting up tarantool-dev (2.1.0.222.g48b98bb~precise-1) ...
$

$ # Use luarocks to install locally, that is, relative to $HOME
$ luarocks install mysql MYSQL_LIBDIR=/usr/local/mysql/lib --local
Installing http://rocks.tarantool.org/mysql-scm-1.rockspec...
... (more info about building the Tarantool/MySQL driver appears here)
mysql scm-1 is now built and installed in ~/.luarocks/

$ # Ensure driver.so now has been created in a place
$ # tarantool will look at
$ find ~/.luarocks -name "driver.so"
~/.luarocks/lib/lua/5.1/mysql/driver.so

$ # Change directory to a directory which can be used for
$ # temporary tests. For this example we assume that the name
$ # of this directory is /home/pgulutzan/tarantool_sandbox.
$ # (Change "/home/pgulutzan" to whatever is the user's actual
$ # home directory for the machine that's used for this test.)
$ cd /home/pgulutzan/tarantool_sandbox

$ # Start the Tarantool server instance. Do not use a Lua initialization file.

$ tarantool
tarantool: version 2.1.0-222-g48b98bb
type 'help' for interactive help
tarantool>

Настройте Tarantool и загрузите модуль mysql. Убедитесь, что Tarantool не выбрасывает ошибку в ответ на вызов «require()».

tarantool> box.cfg{}
...
tarantool> mysql = require('mysql')
---
...

Создайте Lua-функцию, которая подключится к экземпляру MySQL-сервера (используя значения по умолчанию для параметров порта, пользователя и пароля), выберите одну строку и выведите ее на экран. Описание используемых здесь типов операторов вы можете найти в практикуме по Lua в руководстве пользователя Tarantool.

tarantool> function mysql_select ()
         >   local conn = mysql.connect({
         >     host = '127.0.0.1',
         >     port = 3306,
         >     user = 'root',
         >     db = 'test'
         >   })
         >   local test = conn:execute('SELECT * FROM test WHERE s1 = 1')
         >   local row = ''
         >   for i, card in pairs(test) do
         >       row = row .. card.s2 .. ' '
         >       end
         >   conn:close()
         >   return row
         > end
---
...
tarantool> mysql_select()
---
- 'MySQL row '
...

Просмотрите результат. В нем есть строка «MySQL row». Это и есть строка, которая была вставлена в базу данных MySQL. А сейчас она выделена с помощью Tarantool-клиента.

Пример для PostgreSQL

В данном примере предполагается, что установлены PostgreSQL 8 или PostgreSQL 9. Более поздние версии также должны сработать. Самым важным пакетом будет пакет для разработчиков клиента PostgreSQL, который обычно называется libpq-dev. На Ubuntu его можно установить следующим образом:

$ sudo apt-get install libpq-dev

Однако, не все платформы одинаковы, поэтому в данном примере предполагается, что пользователь должен проверить наличие нужных PostgreSQL-файлов, а также явным образом прописать, где они находятся, для сборки драйвера Tarantool/PostgreSQL. Для поиска директорий, где установлены PostgreSQL-файлы, можно воспользоваться командами find или whereis.

Также нужно будет установить библиотеку общего пользования Tarantool с драйвером для PostgreSQL, загрузить ее и использовать для подключения к экземпляру PostgreSQL-сервера. После этого можно передавать любой оператор PostgreSQL на экземпляр сервера и получать результаты.

Установка

Проверьте инструкции по загрузке и установке бинарного пакета, которые применимы к среде, где установлен Tarantool. Помимо установки tarantool, установите tarantool-dev. Например, в Ubuntu добавьте строку:

$ sudo apt-get install tarantool-dev

Что касается библиотеки общего пользования с драйвером для PostgreSQL, ее можно установить двумя способами:

Из LuaRocks

Начните с установки luarocks. Убедитесь, что tarantool указан в серверах, как описано на странице сторонних модулей Tarantool rocks.tarantool.org. Затем выполните:

luarocks install pg [POSTGRESQL_LIBDIR = *путь*]
                    [POSTGRESQL_INCDIR = *путь*]
                    [--local]

Пример:

$ luarocks install pg POSTGRESQL_LIBDIR=/usr/local/postgresql/lib

Из GitHub

Перейдите по ссылке github.com/tarantool/pg. Следуя инструкциям, введите команду:

$ git clone https://github.com/tarantool/pg.git
$ cd pg && cmake . -DCMAKE_BUILD_TYPE=RelWithDebInfo
$ make
$ make install

На данном этапе желательно проверить, что после установки появился файл под названием driver.so, а также проверить, что этот файл находится в директории, которую можно найти по запросу require.

Подключение

Начните с выполнения запроса require для драйвера pg. В дальнейших примерах у него будет имя pg.

pg = require('pg')

Теперь выполните:

*имя_подключения* = pg.connect(*параметры подключения*)

Параметры подключения включены в таблицу. Доступные параметры:

  • host = имя-хоста – строка, значение по умолчанию = „localhost“
  • port = номер-порта – число, значение по умолчанию = 5432
  • user = имя-пользователя – строка, значение по умолчанию – имя пользователя в операционной системе
  • pass = пароль или password = пароль – строка, по умолчанию пустая
  • db = имя-базы-данных – строка, по умолчанию пустая

Имена параметров похожи на имена, которые используются в PostgreSQL.

Пример с использованием таблицы, заключенной в {фигурные скобки}:

conn = pg.connect({
    host = '127.0.0.1',
    port = 5432,
    user = 'p',
    password = 'p',
    db = 'test'
})

Пример с созданием функции, которая определяет параметры в отдельных строках:

tarantool> function pg_connect()
         >   local p = {}
         >   p.host = 'widgets.com'
         >   p.db = 'test'
         >   p.user = 'postgres'
         >   p.password = 'postgres'
         >   local conn = pg.connect(p)
         >   return conn
         > end
---
...
tarantool> conn = pg_connect()
---
...

Предполагаем, что в дальнейших примерах будет использоваться имя „conn“.

Как проверить связь

Чтобы убедиться, что подключение работает, следует использовать запрос:

*имя-соединение*:ping()

Пример:

tarantool> conn:ping()
---
- true
...

Исполнение оператора

Для всех операторов PostgreSQL запрос будет:

*имя-соединения*:execute(*sql-оператор* [, *параметры*])

где sql-statement – это строка, а необязательные параметры – это дополнительные значения, которыми можно заменить любые местозаполнители ($1 $2 $3 и т.д.) в SQL-операторе.

Пример:

tarantool> conn:execute('select tablename from pg_tables')
---
- - tablename: pg_statistic
  - tablename: pg_type
  - tablename: pg_authid
  <...>
...

Закрытие соединения

Чтобы закрыть сессию, которую открыли с помощью pg.connect, используется следующий запрос:

*имя-соединения*:close()

Пример:

tarantool> conn:close()
---
...

For further information, including examples of rarely-used requests, see the README.md file at github.com/tarantool/pg.

Пример

Пример выполняется на машине с ОС Ubuntu 12.04 (Precise Pangolin), где Tarantool установлен в поддиректорию /usr, а копия PostgreSQL установлена в /usr. Экземпляр сервера PostgreSQL уже запущен на localhost 127.0.0.1.

$ # Check that the include subdirectory exists
$ # by looking for /usr/include/postgresql/libpq-fe-h.
$ [ -f /usr/include/postgresql/libpq-fe.h ] && echo "OK" || echo "Error"
OK

$ # Check that the library subdirectory exists and has the necessary .so file.
$ [ -f /usr/lib/x86_64-linux-gnu/libpq.so ] && echo "OK" || echo "Error"
OK

$ # Check that the psql client can connect using some factory defaults:
$ # port = 5432, user = 'postgres', user password = 'postgres',
$ # database = 'postgres'. These can be changed, provided one changes
$ # them in all places. Insert a row in database postgres, and quit.
$ psql -h 127.0.0.1 -p 5432 -U postgres -d postgres
Password for user postgres:
psql (9.3.10)
SSL connection (cipher: DHE-RSA-AES256-SHA, bits: 256)
Type "help" for help.

postgres=# CREATE TABLE test (s1 INT, s2 VARCHAR(50));
CREATE TABLE
postgres=# INSERT INTO test VALUES (1,'PostgreSQL row');
INSERT 0 1
postgres=# \q
$

$ # Install luarocks
$ sudo apt-get -y install luarocks | grep -E "Setting up|already"
Setting up luarocks (2.0.8-2) ...

$ # Set up the Tarantool rock list in ~/.luarocks,
$ # following instructions at rocks.tarantool.org
$ mkdir ~/.luarocks
$ echo "rocks_servers = {[[http://rocks.tarantool.org/]]}" >> \
        ~/.luarocks/config.lua

$ # Ensure that the next "install" will get files from Tarantool master
$ # repository. The resultant display is normal for Ubuntu 12.04 precise
$ cat /etc/apt/sources.list.d/tarantool.list
deb http://tarantool.org/dist/2.0/ubuntu/ precise main
deb-src http://tarantool.org/dist/2.0/ubuntu/ precise main

$ # Install tarantool-dev. The displayed line should show version = 2.0
$ sudo apt-get -y install tarantool-dev | grep -E "Setting up|already"
Setting up tarantool-dev (2.0.4.222.g48b98bb~precise-1) ...
$

$ # Use luarocks to install locally, that is, relative to $HOME
$ luarocks install pg POSTGRESQL_LIBDIR=/usr/lib/x86_64-linux-gnu --local
Installing http://rocks.tarantool.org/pg-scm-1.rockspec...
... (more info about building the Tarantool/PostgreSQL driver appears here)
pg scm-1 is now built and installed in ~/.luarocks/

$ # Ensure driver.so now has been created in a place
$ # tarantool will look at
$ find ~/.luarocks -name "driver.so"
~/.luarocks/lib/lua/5.1/pg/driver.so

$ # Change directory to a directory which can be used for
$ # temporary tests. For this example we assume that the
$ # name of this directory is $HOME/tarantool_sandbox.
$ # (Change "$HOME" to whatever is the user's actual
$ # home directory for the machine that's used for this test.)
cd $HOME/tarantool_sandbox

$ # Start the Tarantool server instance. Do not use a Lua initialization file.

$ tarantool
tarantool: version 2.0.4-412-g803b15c
type 'help' for interactive help
tarantool>

Настройте Tarantool и загрузите модуль pg. Убедитесь, что Tarantool не выбрасывает ошибку в ответ на вызов «require()».

tarantool> box.cfg{}
...
tarantool> pg = require('pg')
---
...

Создайте Lua-функцию, которая подключится к PostgreSQL-серверу (используя значения по умолчанию для параметров порта, пользователя и пароля), выберите одну строку и выведите ее на экран. Описание используемых здесь типов операторов вы можете найти в практикуме по Lua в руководстве пользователя Tarantool.

tarantool> function pg_select ()
         >   local conn = pg.connect({
         >     host = '127.0.0.1',
         >     port = 5432,
         >     user = 'postgres',
         >     password = 'postgres',
         >     db = 'postgres'
         >   })
         >   local test = conn:execute('SELECT * FROM test WHERE s1 = 1')
         >   local row = ''
         >   for i, card in pairs(test) do
         >       row = row .. card.s2 .. ' '
         >       end
         >   conn:close()
         >   return row
         > end
---
...
tarantool> pg_select()
---
- 'PostgreSQL row '
...

Просмотрите результат. В нем есть строка «PostgreSQL row». Это и есть строка, которая была вставлена в базу данных PostgreSQL. А сейчас она выделена с помощью Tarantool-клиента.

Other rocks

This page features a list of links to third-party Tarantool module documentation that is hosted externally – mostly on GitHub pages or in READMEs:

For Tarantool Enterprise modules, see the Tarantool EE documentation.

C API reference

List of C API headers

Module box

type box_function_ctx_t

Opaque structure passed to a C stored procedure

int box_return_tuple(box_function_ctx_t *ctx, box_tuple_t *tuple)

Return a tuple from a C stored procedure.

The returned tuple is automatically reference-counted by Tarantool. An example program that uses box_return_tuple() is write.c.

Параметры:
Результат:

-1 on error (perhaps, out of memory; check box_error_last())
Результат:

0 otherwise
int box_return_mp(box_function_ctx_t *ctx, const char *mp, const char *mp_end)

Return a pointer to a series of bytes in MessagePack format.

This can be used instead of box_return_tuple() – it can send the same value, but as MessagePack instead of as a tuple object. It may be simpler than box_return_tuple() when the result is small, for example a number or a boolean or a short string. It will also be faster than box_return_tuple(), if the result is that users save time by not creating a tuple every time they want to return something from a C function.

On the other hand, if an already-existing tuple was obtained from an iterator, then it would be faster to return the tuple via box_return_tuple() rather than extracting its parts and sending them via box_return_mp().

Параметры:
  • ctx (box_function_ctx_t*) – an opaque structure passed to the C stored procedure by Tarantool
  • mp (char*) – the first MessagePack byte
  • mp_end (char*) – after the last MessagePack byte
Результат:

-1 on error (perhaps, out of memory; check box_error_last())
Результат:

0 otherwise

For example, if mp is a buffer, and mp_end is a return value produced by encoding a single MP_UINT scalar value with mp_end=mp_encode_uint(mp,1);, then box_return_mp(ctx,mp,mp_end); should return 0.

uint32_t box_space_id_by_name(const char *name, uint32_t len)

Find space id by name.

This function performs a SELECT request on the _vspace system space.

Параметры:
  • name (const char*) – space name
  • len (uint32_t) – length of name
Результат:

BOX_ID_NIL on error or if not found (check box_error_last())
Результат:

space_id otherwise

See also: box_index_id_by_name

uint32_t box_index_id_by_name(uint32_t space_id, const char *name, uint32_t len)

Find index id by name.

This function performs a SELECT request on the _vindex system space.

Параметры:
  • space_id (uint32_t) – space identifier
  • name (const char*) – index name
  • len (uint32_t) – length of name
Результат:

BOX_ID_NIL on error or if not found (check box_error_last())
Результат:

space_id otherwise

See also: box_space_id_by_name

int box_insert(uint32_t space_id, const char *tuple, const char *tuple_end, box_tuple_t **result)

Execute an INSERT/REPLACE request.

Параметры:
  • space_id (uint32_t) – space identifier
  • tuple (const char*) – encoded tuple in MsgPack Array format ([ field1, field2, …])
  • tuple_end (const char*) – end of a tuple
  • result (box_tuple_t**) – output argument. Resulting tuple. Can be set to NULL to discard result
Результат:

-1 on error (check box_error_last())
Результат:

0 otherwise

See also: space_object.insert()

int box_replace(uint32_t space_id, const char *tuple, const char *tuple_end, box_tuple_t **result)

Execute a REPLACE request.

Параметры:
  • space_id (uint32_t) – space identifier
  • tuple (const char*) – encoded tuple in MsgPack Array format ([ field1, field2, …])
  • tuple_end (const char*) – end of a tuple
  • result (box_tuple_t**) – output argument. Resulting tuple. Can be set to NULL to discard result
Результат:

-1 on error (check box_error_last())
Результат:

0 otherwise

See also: space_object.replace()

int box_delete(uint32_t space_id, uint32_t index_id, const char *key, const char *key_end, box_tuple_t **result)

Execute a DELETE request.

Параметры:
  • space_id (uint32_t) – space identifier
  • index_id (uint32_t) – index identifier
  • key (const char*) – encoded key in MsgPack Array format ([ field1, field2, …])
  • key_end (const char*) – end of a key
  • result (box_tuple_t**) – output argument. An old tuple. Can be set to NULL to discard result
Результат:

-1 on error (check box_error_last())
Результат:

0 otherwise

See also: space_object.delete()

int box_update(uint32_t space_id, uint32_t index_id, const char *key, const char *key_end, const char *ops, const char *ops_end, int index_base, box_tuple_t **result)

Execute an UPDATE request.

Параметры:
  • space_id (uint32_t) – space identifier
  • index_id (uint32_t) – index identifier
  • key (const char*) – encoded key in MsgPack Array format ([ field1, field2, …])
  • key_end (const char*) – end of a key
  • ops (const char*) – encoded operations in MsgPack Array format, e.g. [[ '=', field_id,  value ], ['!', 2, 'xxx']]
  • ops_end (const char*) – end of an ops section
  • index_base (int) – 0 if field_ids are zero-based as in C, 1 if field ids are 1-based as in Lua
  • result (box_tuple_t**) – output argument. An old tuple. Can be set to NULL to discard result
Результат:

-1 on error (check box_error_last())
Результат:

0 otherwise

See also: space_object.update()

int box_upsert(uint32_t space_id, uint32_t index_id, const char *tuple, const char *tuple_end, const char *ops, const char *ops_end, int index_base, box_tuple_t **result)

Execute an UPSERT request.

Параметры:
  • space_id (uint32_t) – space identifier
  • index_id (uint32_t) – index identifier
  • tuple (const char*) – encoded tuple in MsgPack Array format ([ field1, field2, …])
  • tuple_end (const char*) – end of a tuple
  • ops (const char*) – encoded operations in MsgPack Array format, e.g. [[ '=', field_id,  value ], ['!', 2, 'xxx']]
  • ops_end (const char*) – end of a ops
  • index_base (int) – 0 if field_ids are zero-based as in C, 1 if field ids are 1-based as in Lua
  • result (box_tuple_t**) – output argument. An old tuple. Can be set to NULL to discard result
Результат:

-1 on error (check box_error_last())
Результат:

0 otherwise

See also: space_object.upsert()

int box_truncate(uint32_t space_id)

Truncate a space.

Параметры:
  • space_id (uint32_t) – space identifier
int box_session_push(const char *data, const char *data_end)

Since version 2.4.1. Push MessagePack data into a session data channel – socket, console or whatever is behind the session. Behaves just like Lua box.session.push().

Параметры:
  • data (const char*) – begin of MessagePack to push
  • data_end (const char*) – end of MessagePack to push
Результат:

-1 on error (check box_error_last())
Результат:

0 otherwise
int box_sequence_current(uint32_t seq_id, int64_t *result)

Since version 2.4.1. Return the last retrieved value of the specified sequence.

Параметры:
  • seq_id (uint32_t) – sequence identifier
  • result (int64_t) – pointer to a variable where the current sequence value will be stored on success.
Результат:

0 on success and -1 otherwise. In case of an error user could get it via box_error_last().
uint32_t box_schema_version(void)

Since version 2.11.0. Return the database schema version. A schema version is a number that indicates whether the database schema is changed. For example, the schema_version value grows if a space or index is added or deleted, or a space, index, or field name is changed.

Результат:the database schema version
Тип результата:number

See also: box.info.schema_version and IPROTO_SCHEMA_VERSION

uint64_t box_session_id(void)

Since version 2.11.0. Return the unique identifier (ID) for the current session.

Результат:the session identifier; 0 or -1 if there is no session
Тип результата:number

See also: box.session.id()

int box_iproto_send(uint64_t sid, char *header, char *header_end[, char *body, char *body_end])

Since version 2.11.0. Send an IPROTO packet over the session’s socket with the given MsgPack header and body. The function yields. The function works for binary sessions only. For details, see box.session.type().

Параметры:
  • sid (uint32_t) – the IPROTO session identifier (see box_session_id())
  • header (char*) – a MsgPack-encoded header
  • header_end (char*) – end of a header encoded as MsgPack
  • body (char*) – a MsgPack-encoded body. If the body and body_end parameters are omitted, the packet consists of the header only.
  • body_end (char*) – end of a body encoded as MsgPack
Результат:

0 on success; -1 on error (check box_error_last())
Тип результата:

number

See also: box.iproto.send()

Possible errors:

  • ER_SESSION_CLOSED – the session is closed.
  • ER_NO_SUCH_SESSION – the session does not exist.
  • ER_MEMORY_ISSUE – out-of-memory limit has been reached.
  • ER_WRONG_SESSION_TYPE – the session type is not binary.

For details, see src/box/errcode.h.

Example

/* IPROTO constants are not exported to C.
* That is, the user encodes them by himself.
*/
#define IPROTO_REQUEST_TYPE 0x00
#define IPROTO_OK 0x00
#define IPROTO_SYNC 0x01
#define IPROTO_SCHEMA_VERSION 0x05
#define IPROTO_DATA 0x30

char buf[256] = {};
char *header = buf;
char *header_end = header;
header_end = mp_encode_map(header_end, 3);
header_end = mp_encode_uint(header_end, IPROTO_REQUEST_TYPE);
header_end = mp_encode_uint(header_end, IPROTO_OK);
header_end = mp_encode_uint(header_end, IPROTO_SYNC);
header_end = mp_encode_uint(header_end, 10);
header_end = mp_encode_uint(header_end, IPROTO_SCHEMA_VERSION);
header_end = mp_encode_uint(header_end, box_schema_version());

char *body = header_end;
char *body_end = body;
body_end = mp_encode_map(body_end, 1);
body_end = mp_encode_uint(body_end, IPROTO_DATA);
body_end = mp_encode_uint(body_end, 1);

/* The packet contains both the header and body. */
box_iproto_send(box_session_id(), header, header_end, body, body_end);

/* The packet contains the header only. */
box_iproto_send(box_session_id(), header, header_end, NULL, NULL);
void box_iproto_override(uint32_t request_type, iproto_handler_t handler, iproto_handler_destroy_t destroy, void *ctx)

Since version 2.11.0. Set a new IPROTO request handler with the provided context for the given request type. The function yields.

Параметры:
  • request_type (uint32_t) –

    IPROTO request type code (for example, IPROTO_SELECT). For details, check Client-server requests and responses.

    To override the handler of unknown request types, use the IPROTO_UNKNOWN type code.

  • handler (iproto_handler_t) – IPROTO request handler. To reset the request handler, set the handler parameter to NULL. See the full parameter description in the Handler function section.
  • destroy (iproto_handler_destroy_t) – IPROTO request handler destructor. The destructor is called when the corresponding handler is removed. See the full parameter description in the Handler destructor function section.
  • ctx (void*) – a context passed to the handler and destroy callbacks
Результат:

0 on success; -1 on error (check box_error_last())
Тип результата:

number

See also: box.iproto.override()

Possible errors:

If a Lua handler throws an exception, the behavior is similar to that of a remote procedure call. The following errors are returned to the client over IPROTO (see src/lua/utils.h):

  • ER_PROC_LUA – an exception is thrown from a Lua handler, diagnostic is not set.
  • diagnostics from src/box/errcode.h – an exception is thrown, diagnostic is set.

For details, see src/box/errcode.h.

Handler function

The signature of a handler function (the handler parameter):

enum iproto_handler_status {
        IPROTO_HANDLER_OK,
        IPROTO_HANDLER_ERROR,
        IPROTO_HANDLER_FALLBACK,
}

typedef enum iproto_handler_status
(*iproto_handler_t)(const char *header, const char *header_end,
                    const char *body, const char *body_end, void *ctx);

where:

  • header (const char*) – a MsgPack-encoded header
  • header_end (const char*) – end of a header encoded as MsgPack
  • body (const char*) – a MsgPack-encoded body
  • header_end (const char*) – end of a body encoded as MsgPack

The handler returns a status code. Possible statuses:

  • IPROTO_REQUEST_HANDLER_OK – success
  • IPROTO_REQUEST_HANDLER_ERROR – error, diagnostic must be set by handler (see box_error_set() and box_error_raise())
  • IPROTO_REQUEST_HANDLER_FALLBACK – fallback to the default handler

Handler destructor function

The destructor is called when the handler is reset. The signature of a destructor function (the destroy parameter):

typedef void (*iproto_handler_destroy_t)(void *ctx);

where:

  • ctx (void*): the context provided by box_iproto_override() function.

Examples

box_iproto_override(1000, iproto_request_handler_с, NULL)
box_iproto_override(IPROTO_SELECT, iproto_request_handler_с, (uintptr_t)23)
box_iproto_override(IPROTO_SELECT, NULL, NULL)
box_iproto_override(IPROTO_UNKNOWN, iproto_unknown_request_handler_с, &ctx)

Module clock

double clock_realtime(void)
double clock_monotonic(void)
double clock_process(void)
double clock_thread(void)
int64_t clock_realtime64(void)
int64_t clock_monotonic64(void)
int64_t clock_process64(void)
int64_t clock_thread64(void)

Module coio

enum COIO_EVENT
enumerator ::COIO_READ

READ event

enumerator ::COIO_WRITE

WRITE event

int coio_wait(int fd, int event, double timeout)

Wait until READ or WRITE event on socket (fd). Yields.

Параметры:
  • fd (int) – non-blocking socket file description
  • event (int) – requested events to wait. Combination of COIO_READ | COIO_WRITE bit flags.
  • timeout (double) – timeout in seconds.
Результат:

0 - timeout
Результат:

>0 - returned events. Combination of TNT_IO_READ | TNT_IO_WRITE bit flags.
ssize_t coio_call(ssize_t (*func)(va_list), ...)

Create new eio task with specified function and arguments. Yield and wait until the task is complete. This function may use the worker_pool_threads configuration parameter.

To avoid double error checking, this function does not throw exceptions. In most cases it is also necessary to check the return value of the called function and perform necessary actions. If func sets errno, the errno is preserved across the call.

Результат:-1 and errno = ENOMEM if failed to create a task
Результат:the function’s return (errno is preserved).

Example:

static ssize_t openfile_cb(va_list ap)
{
        const char* filename = va_arg(ap);
        int flags = va_arg(ap);
        return open(filename, flags);
}

if (coio_call(openfile_cb, "/tmp/file", 0) == -1)
    // handle errors.
...
int coio_getaddrinfo(const char *host, const char *port, const struct addrinfo *hints, struct addrinfo **res, double timeout)

Fiber-friendly version of getaddrinfo(3).

int coio_close(int fd)

Close the fd and wake any fiber blocked in coio_wait() call on this fd.

Параметры:
  • fd (int) – non-blocking socket file description
Результат:

the result of close(fd), see close(2)

Module error

enum box_error_code

For a complete list of errors, refer to the Tarantool error code header file.

type box_error_t

Error – contains information about error.

const char *box_error_type(const box_error_t *error)

Return the error type, e.g. «ClientError», «SocketError», etc.

Параметры:
Результат:

not-null string
uint32_t box_error_code(const box_error_t *error)

Return IPROTO error code

Параметры:
Результат:

box_error_code
const char *box_error_message(const box_error_t *error)

Return the error message

Параметры:
Результат:

not-null string
box_error_t *box_error_last(void)

Get the information about the last API call error.

The Tarantool error handling works most like libc’s errno. All API calls return -1 or NULL in the event of error. An internal pointer to box_error_t type is set by API functions to indicate what went wrong. This value is only significant if API call failed (returned -1 or NULL).

Successful function can also touch the last error in some cases. You don’t have to clear the last error before calling API functions. The returned object is valid only until next call to any API function.

You must set the last error using box_error_set() in your stored C procedures if you want to return a custom error message. You can re-throw the last API error to IPROTO client by keeping the current value and returning -1 to Tarantool from your stored procedure.

Результат:last error
void box_error_clear(void)

Clear the last error.

int box_error_set(const char *file, unsigned line, uint32_t code, const char *format, ...)

Set the last error.

Параметры:
  • file (const char*) –
  • line (unsigned) –
  • code (uint32_t) – IPROTO error code
  • format (const char*) –
  • ... – format arguments

See also: IPROTO error code

box_error_raise(code, format, ...)

A backward-compatible API define.

Module fiber

type fiber

Fiber - contains information about a fiber.

typedef int (*fiber_func)(va_list)

Function to run inside a fiber.

fiber *fiber_new(const char *name, fiber_func f)

Create a new fiber.

Takes a fiber from the fiber cache, if it’s not empty. Can fail only if there is not enough memory for the fiber structure or fiber stack.

The created fiber automatically returns itself to the fiber cache when its «main» function completes.

Параметры:
  • name (const char*) – string with fiber name
  • f (fiber_func) – func for run inside fiber

See also: fiber_start()

fiber *fiber_new_ex(const char *name, const struct fiber_attr *fiber_attr, fiber_func f)

Create a new fiber with defined attributes.

Can fail only if there is not enough memory for the fiber structure or fiber stack.

The created fiber automatically returns itself to the fiber cache if has a default stack size when its «main» function completes.

Параметры:
  • name (const char*) – string with fiber name
  • fiber_attr (const struct fiber_attr*) – fiber attributes container
  • f (fiber_func) – function to run inside the fiber

See also: fiber_start()

void fiber_start(struct fiber *callee, ...)

Start execution of created fiber.

Параметры:
  • callee (struct fiber*) – fiber to start
  • ... – arguments to start the fiber with
void fiber_yield(void)

Return control to another fiber and wait until it’ll be woken.

See also: fiber_wakeup()

void fiber_wakeup(struct fiber *f)

Interrupt a synchronous wait of a fiber

Параметры:
  • f (struct fiber*) – fiber to be woken up
void fiber_cancel(struct fiber *f)

Cancel the subject fiber.

Cancellation is asynchronous. Use fiber_join() to wait for the cancellation to complete.

After fiber_cancel() is called, the fiber may or may not check whether it was cancelled. If the fiber does not check it, it cannot ever be cancelled.

Параметры:
  • f (struct fiber*) – fiber to be cancelled
bool fiber_set_cancellable(bool yesno)

Deprecated since 2.11.0. Make it possible or not possible to wakeup the current fiber immediately when it’s cancelled.

Параметры:
  • f (struct fiber*) – fiber
  • yesno (bool) – status to set
Результат:

previous state
void fiber_set_joinable(struct fiber *fiber, bool yesno)

Set fiber to be joinable (false by default).

Параметры:
  • f (struct fiber*) – fiber
  • yesno (bool) – status to set
void fiber_join(struct fiber *f)

Wait until the fiber is dead and then move its execution status to the caller. The fiber must not be detached.

Параметры:
  • f (struct fiber*) – fiber to be woken up

Before: FIBER_IS_JOINABLE flag is set.

See also: fiber_set_joinable()

void fiber_sleep(double s)

Put the current fiber to sleep for at least „s“ seconds.

Параметры:
  • s (double) – time to sleep

Note: this is a cancellation point.

See also: fiber_is_cancelled()

bool fiber_is_cancelled(void)

Check current fiber for cancellation (it must be checked manually).

double fiber_time(void)

Report loop begin time as double (cheap).

int64_t fiber_time64(void)

Report loop begin time as 64-bit int. Uses real time clock.

double fiber_clock(void)

Report loop begin time as double (cheap). Uses monotonic clock.

int64_t fiber_clock64(void)

Report loop begin time as 64-bit int. Uses monotonic clock.

void fiber_reschedule(void)

Reschedule fiber to end of event loop cycle.

type slab_cache
struct slab_cache *cord_slab_cache(void)

Return slab_cache suitable to use with tarantool/small library

fiber *fiber_self(void)

Return the current fiber.

type fiber_attr
void fiber_attr_new(void)

Create a new fiber attributes container and initialize it with default parameters.

Can be used for creating many fibers: corresponding fibers will not take ownership.

void fiber_attr_delete(struct fiber_attr *fiber_attr)

Delete the fiber_attr and free all allocated resources. This is safe when fibers created with this attribute still exist.

Параметры:
  • fiber_attribute (struct fiber_attr*) – fiber attributes container
int fiber_attr_setstacksize(struct fiber_attr *fiber_attr, size_t stack_size)

Set the fiber’s stack size in the fiber attributes container.

Параметры:
  • fiber_attr (struct fiber_attr*) – fiber attributes container
  • stack_size (size_t) – stack size for new fibers (in bytes)
Результат:

0 on success
Результат:

-1 on failure (if stack_size is smaller than the minimum allowable fiber stack size)
size_t fiber_attr_getstacksize(struct fiber_attr *fiber_attr)

Get the fiber’s stack size from the fiber attributes container.

Параметры:
  • fiber_attr (struct fiber_attr*) – fiber attributes container, or NULL for default
Результат:

stack size (in bytes)
type fiber_cond

A conditional variable: a synchronization primitive that allow fibers in Tarantool’s cooperative multitasking environment to yield until some predicate is satisfied.

Fiber conditions have two basic operations – «wait» and «signal», – where «wait» suspends the execution of a fiber (i.e. yields) until «signal» is called.

Unlike pthread_cond, fiber_cond doesn’t require mutex/latch wrapping.

struct fiber_cond *fiber_cond_new(void)

Create a new conditional variable.

void fiber_cond_delete(fiber_cond *cond)

Delete the conditional variable.

Note: behavior is undefined if there are fibers waiting for the conditional variable.

Параметры:
  • cond (struct fiber_cond*) – conditional variable to delete
void fiber_cond_signal(struct fiber_cond *cond);

Wake up one (any) of the fibers waiting for the conditional variable.

Does nothing if no one is waiting.

Параметры:
  • cond (struct fiber_cond*) – conditional variable
void fiber_cond_broadcast(struct fiber_cond *cond);

Wake up all fibers waiting for the conditional variable.

Does nothing if no one is waiting.

Параметры:
  • cond (struct fiber_cond*) – conditional variable
int fiber_cond_wait_timeout(struct fiber_cond *cond, double timeout)

Suspend the execution of the current fiber (i.e. yield) until fiber_cond_signal() is called.

Like pthread_cond, fiber_cond can issue spurious wake ups caused by explicit fiber_wakeup() or fiber_cancel() calls. It is highly recommended to wrap calls to this function into a loop and check the actual predicate and fiber_is_cancelled() on every iteration.

Параметры:
  • cond (struct fiber_cond*) – conditional variable
  • timeout (double) – timeout in seconds
Результат:

0 on fiber_cond_signal() call or a spurious wake up
Результат:

-1 on timeout, and the error code is set to „TimedOut“
int fiber_cond_wait(struct fiber_cond *cond)

Shortcut for fiber_cond_wait_timeout().

Module index

type box_iterator_t

A space iterator

enum iterator_type

Controls how to iterate over tuples in an index. Different index types support different iterator types. For example, one can start iteration from a particular value (request key) and then retrieve all tuples where keys are greater or equal (= GE) to this key.

If iterator type is not supported by the selected index type, iterator constructor must fail with ER_UNSUPPORTED. To be selectable for primary key, an index must support at least ITER_EQ and ITER_GE types.

NULL value of request key corresponds to the first or last key in the index, depending on iteration direction. (first key for GE and GT types, and last key for LE and LT). Therefore, to iterate over all tuples in an index, one can use ITER_GE or ITER_LE iteration types with start key equal to NULL. For ITER_EQ, the key must not be NULL.

enumerator ::ITER_EQ

key == x ASC order

enumerator ::ITER_REQ

key == x DESC order

enumerator ::ITER_ALL

all tuples

enumerator ::ITER_LT

key < x

enumerator ::ITER_LE

key <= x

enumerator ::ITER_GE

key >= x

enumerator ::ITER_GT

key > x

enumerator ::ITER_BITS_ALL_SET

all bits from x are set in key

enumerator ::ITER_BITS_ANY_SET

at least one x’s bit is set

enumerator ::ITER_BITS_ALL_NOT_SET

all bits are not set

enumerator ::ITER_OVERLAPS

key overlaps x

enumerator ::ITER_NEIGHBOR

tuples in distance ascending order from specified point

box_iterator_t *box_index_iterator(uint32_t space_id, uint32_t index_id, int type, const char *key, const char *key_end)

Allocate and initialize iterator for space_id, index_id.

The returned iterator must be destroyed by box_iterator_free.

Параметры:
  • space_id (uint32_t) – space identifier
  • index_id (uint32_t) – index identifier
  • type (int) – iterator_type
  • key (const char*) – encode key in MsgPack Array format ([part1, part2, …])
  • key_end (const char*) – the end of encoded key
Результат:

NULL on error (check box_error_last)
Результат:

iterator otherwise

See also box_iterator_next, box_iterator_free

int box_iterator_next(box_iterator_t *iterator, box_tuple_t **result)

Retrieve the next item from the iterator.

Параметры:
Результат:

-1 on error (check box_error_last)
Результат:

0 on success. The end of data is not an error.
void box_iterator_free(box_iterator_t *iterator)

Destroy and deallocate iterator.

Параметры:
int iterator_direction(enum iterator_type type)

Determine a direction of the given iterator type: -1 for REQ, LT, LE, and +1 for all others.

ssize_t box_index_len(uint32_t space_id, uint32_t index_id)

Return the number of element in the index.

Параметры:
  • space_id (uint32_t) – space identifier
  • index_id (uint32_t) – index identifier
Результат:

-1 on error (check box_error_last)
Результат:

>= 0 otherwise
ssize_t box_index_bsize(uint32_t space_id, uint32_t index_id)

Return the number of bytes used in memory by the index.

Параметры:
  • space_id (uint32_t) – space identifier
  • index_id (uint32_t) – index identifier
Результат:

-1 on error (check box_error_last)
Результат:

>= 0 otherwise
int box_index_random(uint32_t space_id, uint32_t index_id, uint32_t rnd, box_tuple_t **result)

Return a random tuple from the index (useful for statistical analysis).

Параметры:
  • space_id (uint32_t) – space identifier
  • index_id (uint32_t) – index identifier
  • rnd (uint32_t) – random seed
  • result (box_tuple_t**) – output argument. result a tuple or NULL if there is no tuples in space

See also: index_object:random()

int box_index_get(uint32_t space_id, uint32_t index_id, const char *key, const char *key_end, box_tuple_t **result)

Get a tuple from index by the key.

Please note that this function works much more faster than index_object:select() or box_index_iterator + box_iterator_next.

Параметры:
  • space_id (uint32_t) – space identifier
  • index_id (uint32_t) – index identifier
  • key (const char*) – encode key in MsgPack Array format ([part1, part2, …])
  • key_end (const char*) – the end of encoded key
  • result (box_tuple_t**) – output argument. result a tuple or NULL if there is no tuples in space
Результат:

-1 on error (check box_error_last)
Результат:

0 on success

See also: index_object.get()

int box_index_min(uint32_t space_id, uint32_t index_id, const char *key, const char *key_end, box_tuple_t **result)

Return a first (minimal) tuple matched the provided key.

Параметры:
  • space_id (uint32_t) – space identifier
  • index_id (uint32_t) – index identifier
  • key (const char*) – encode key in MsgPack Array format ([part1, part2, …])
  • key_end (const char*) – the end of encoded key
  • result (box_tuple_t**) – output argument. result a tuple or NULL if there is no tuples in space
Результат:

-1 on error (check box_error_last())
Результат:

0 on success

See also: index_object:min()

int box_index_max(uint32_t space_id, uint32_t index_id, const char *key, const char *key_end, box_tuple_t **result)

Return a last (maximal) tuple matched the provided key.

Параметры:
  • space_id (uint32_t) – space identifier
  • index_id (uint32_t) – index identifier
  • key (const char*) – encode key in MsgPack Array format ([part1, part2, …])
  • key_end (const char*) – the end of encoded key
  • result (box_tuple_t**) – output argument. result a tuple or NULL if there is no tuples in space
Результат:

-1 on error (check box_error_last())
Результат:

0 on success

See also: index_object:max()

ssize_t box_index_count(uint32_t space_id, uint32_t index_id, int type, const char *key, const char *key_end)

Count the number of tuple matched the provided key.

Параметры:
  • space_id (uint32_t) – space identifier
  • index_id (uint32_t) – index identifier
  • type (int) – iterator_type
  • key (const char*) – encode key in MsgPack Array format ([part1, part2, …])
  • key_end (const char*) – the end of encoded key
Результат:

-1 on error (check box_error_last())
Результат:

0 on success

See also: index_object.count()

const box_key_def_t *box_index_key_def(uint32_t space_id, uint32_t index_id)

Return key definition for an index

Returned object is valid until the next yield.

Параметры:
  • space_id (uint32_t) – space identifier
  • index_id (uint32_t) – index identifier
Результат:

key definition on success
Результат:

NULL on error
See also: box_tuple_compare(),
box_tuple_format_new()

Module latch

type box_latch_t

A lock for cooperative multitasking environment

box_latch_t *box_latch_new(void)

Allocate and initialize the new latch.

Результат:allocated latch object
Тип результата:box_latch_t *
void box_latch_delete(box_latch_t *latch)

Destroy and free the latch.

Параметры:
void box_latch_lock(box_latch_t *latch)

Lock a latch. Waits indefinitely until the current fiber can gain access to the latch. Since version 2.11.0, locks are acquired exactly in the order in which they were requested.

Параметры:
int box_latch_trylock(box_latch_t *latch)

Try to lock a latch. Return immediately if the latch is locked.

Параметры:
Результат:

status of operation. 0 - success, 1 - latch is locked
Тип результата:

int
void box_latch_unlock(box_latch_t *latch)

Unlock a latch. The fiber calling this function must own the latch.

Параметры:

Function on_shutdown

int box_on_shutdown(void *arg, int (*new_handler)(void*), int (*old_handler)(void*))

Register and/or deregister an on_shutdown function.

Параметры:
  • arg (void*) – Pointer to an area that the new handler can use
  • new_handler (function*) – Pointer to a function which will be registered, or NULL
  • old_handler (function*) – Pointer to a function which will be deregistered, or NULL
Результат:

status of operation. 0 - success, -1 - failure
Тип результата:

int

A function which is registered will be called when the Tarantool instance shuts down. This is functionally similar to what box.ctl.on_shutdown does.

If there are several on_shutdown functions, the Tarantool instance will call them in reverse order of registration, that is, it will call the last-registered function first.

Typically a module developer will register an on_shutdown function that does whatever cleanup work the module requires, and then returns control to the Tarantool instance. Such an on_shutdown function should be fast, or should use an asynchronous waiting mechanism (for example coio_wait).

Possible errors: old_handler does not exist (errno = EINVAL), new_handler and old_handler are both NULL (errno = EINVAL), memory allocation fails (errno = ENOMEM).

Example: if the C API .c program contains a function int on_shutdown_function(void *arg) {printf("Bye!\n");return 0; } and later, in the function which the instance calls, contains a line box_on_shutdown(NULL, on_shutdown_function, NULL); then, if all goes well, when the instance shuts down, it will display «Bye!».

Added in version 2.8.1.

Module lua/utils

void *luaL_pushcdata(struct lua_State *L, uint32_t ctypeid)

Push cdata of given ctypeid onto the stack.

CTypeID must be used from FFI at least once. Allocated memory returned uninitialized. Only numbers and pointers are supported.

Параметры:
  • L (lua_State*) – Lua State
  • ctypeid (uint32_t) – FFI’s CTypeID of this cdata
Результат:

memory associated with this cdata

See also: luaL_checkcdata()

void *luaL_checkcdata(struct lua_State *L, int idx, uint32_t *ctypeid)

Check whether the function argument idx is a cdata.

Параметры:
  • L (lua_State*) – Lua State
  • idx (int) – stack index
  • ctypeid (uint32_t*) – output argument. FFI’s CTypeID of returned cdata
Результат:

memory associated with this cdata

See also: luaL_pushcdata()

void luaL_setcdatagc(struct lua_State *L, int idx)

Set finalizer function on a cdata object.

Equivalent to call ffi.gc(obj, function). Finalizer function must be on the top of the stack.

Параметры:
  • L (lua_State*) – Lua State
  • idx (int) – stack index
uint32_t luaL_ctypeid(struct lua_State *L, const char *ctypename)

Return CTypeID (FFI) of given СDATA type.

Параметры:
  • L (lua_State*) – Lua State
  • ctypename (const char*) – C type name as string (e.g. «struct request» or «uint32_t»)
Результат:

CTypeID

See also: luaL_pushcdata(), luaL_checkcdata()

int luaL_cdef(struct lua_State *L, const char *ctypename)

Declare symbols for FFI.

Параметры:
  • L (lua_State*) – Lua State
  • ctypename (const char*) – C definitions (e.g. «struct stat»)
Результат:

0 on success
Результат:

LUA_ERRRUN, LUA_ERRMEM or LUA_ERRERR otherwise.

See also: ffi.cdef(def)

void luaL_pushuint64(struct lua_State *L, uint64_t val)

Push uint64_t onto the stack.

Параметры:
  • L (lua_State*) – Lua State
  • val (uint64_t) – value to push
void luaL_pushint64(struct lua_State *L, int64_t val)

Push int64_t onto the stack.

Параметры:
  • L (lua_State*) – Lua State
  • val (int64_t) – value to push
uint64_t luaL_checkuint64(struct lua_State *L, int idx)

Check whether the argument idx is a uint64 or a convertible string and returns this number.

Throws:error if the argument can’t be converted
uint64_t luaL_checkint64(struct lua_State *L, int idx)

Check whether the argument idx is a int64 or a convertible string and returns this number.

Throws:error if the argument can’t be converted
uint64_t luaL_touint64(struct lua_State *L, int idx)

Check whether the argument idx is a uint64 or a convertible string and returns this number.

Результат:the converted number or 0 of argument can’t be converted
int64_t luaL_toint64(struct lua_State *L, int idx)

Check whether the argument idx is a int64 or a convertible string and returns this number.

Результат:the converted number or 0 of argument can’t be converted
void luaT_pushtuple(struct lua_State *L, box_tuple_t *tuple)

Push a tuple onto the stack.

Параметры:
  • L (lua_State*) – Lua State
Throws:

error on OOM

See also: luaT_istuple

box_tuple_t *luaT_istuple(struct lua_State *L, int idx)

Check whether idx is a tuple.

Параметры:
  • L (lua_State*) – Lua State
  • idx (int) – the stack index
Результат:

non-NULL if idx is a tuple
Результат:

NULL if idx is not a tuple
int luaT_error(lua_State *L)

Re-throw the last Tarantool error as a Lua object.

See also: lua_error(),
box_error_last().
int luaT_cpcall(lua_State *L, lua_CFunction func, void *ud)

Similar to lua_cpcall(), but with the proper support of Tarantool errors.

lua_State *luaT_state(void)

Get the global Lua state used by Tarantool.

Module say (logging)

enum say_level
enumerator ::S_FATAL

do not use this value directly

enumerator ::S_SYSERROR
enumerator ::S_ERROR
enumerator ::S_CRIT
enumerator ::S_WARN
enumerator ::S_INFO
enumerator ::S_VERBOSE
enumerator ::S_DEBUG
say(level, format, ...)

Format and print a message to Tarantool log file.

Параметры:
  • level (int) – log level
  • format (const char*) – printf()-like format string
  • ... – format arguments

See also printf(3), say_level

say_error(format, ...)
say_crit(format, ...)
say_warn(format, ...)
say_info(format, ...)
say_verbose(format, ...)
say_debug(format, ...)
say_syserror(format, ...)

Format and print a message to Tarantool log file.

Параметры:
  • format (const char*) – printf()-like format string
  • ... – format arguments

See also printf(3), say_level

Example:

say_info("Some useful information: %s", status);

Module schema

enum SCHEMA
enumerator ::BOX_SYSTEM_ID_MIN

Start of the reserved range of system spaces.

enumerator ::BOX_SCHEMA_ID

Space id of _schema.

enumerator ::BOX_SPACE_ID

Space id of _space.

enumerator ::BOX_VSPACE_ID

Space id of _vspace view.

enumerator ::BOX_INDEX_ID

Space id of _index.

enumerator ::BOX_VINDEX_ID

Space id of _vindex view.

enumerator ::BOX_FUNC_ID

Space id of _func.

enumerator ::BOX_VFUNC_ID

Space id of _vfunc view.

enumerator ::BOX_USER_ID

Space id of _user.

enumerator ::BOX_VUSER_ID

Space id of _vuser view.

enumerator ::BOX_PRIV_ID

Space id of _priv.

enumerator ::BOX_VPRIV_ID

Space id of _vpriv view.

enumerator ::BOX_CLUSTER_ID

Space id of _cluster.

enumerator ::BOX_TRIGGER_ID

Space id of _trigger.

enumerator ::BOX_TRUNCATE_ID

Space id of _truncate.

enumerator ::BOX_SYSTEM_ID_MAX

End of reserved range of system spaces.

enumerator ::BOX_ID_NIL

NULL value, returned on error.

Module trivia/config

API_EXPORT

Extern modifier for all public functions.

PACKAGE_VERSION_MAJOR

Package major version - 2 for 2.0.5.

PACKAGE_VERSION_MINOR

Package minor version - 0 for 2.0.5.

PACKAGE_VERSION_PATCH

Package patch version - 5 for 2.0.5.

PACKAGE_VERSION

A string with major-minor-patch-commit-id identifier of the release, e.g. 2.0.5-75-gdd8e14ffb.

SYSCONF_DIR

System configuration dir (e.g /etc)

INSTALL_PREFIX

Install prefix (e.g. /usr)

BUILD_TYPE

Build type, e.g. Debug or Release

BUILD_INFO

CMake build type signature, e.g. Linux-x86_64-Debug

BUILD_OPTIONS

Command line used to run CMake.

COMPILER_INFO

Paths to C and CXX compilers.

TARANTOOL_C_FLAGS

C compile flags used to build Tarantool.

TARANTOOL_CXX_FLAGS

CXX compile flags used to build Tarantool.

MODULE_LIBDIR

A path to install *.lua module files.

MODULE_LUADIR

A path to install *.so/*.dylib module files.

MODULE_INCLUDEDIR

A path to Lua includes (the same directory where this file is contained)

MODULE_LUAPATH

A constant added to package.path in Lua to find *.lua module files.

MODULE_LIBPATH

A constant added to package.cpath in Lua to find *.so module files.

Module tuple

type box_tuple_format_t
box_tuple_format_t *box_tuple_format_default(void)

Tuple format.

Each Tuple has an associated format (class). Default format is used to create tuples which are not attached to any particular space.

type box_tuple_t

Tuple

box_tuple_t *box_tuple_new(box_tuple_format_t *format, const char *tuple, const char *tuple_end)

Allocate and initialize a new tuple from raw MsgPack Array data.

Параметры:
  • format (box_tuple_format_t*) – tuple format. Use box_tuple_format_default() to create space-independent tuple.
  • tuple (const char*) – tuple data in MsgPack Array format ([field1, field2, …])
  • tuple_end (const char*) – the end of data
Результат:

NULL on out of memory
Результат:

tuple otherwise

See also: box.tuple.new()

Предупреждение

When working with tuples, it is the developer’s responsibility to ensure that enough space is allocated, taking especial caution when writing to them with msgpuck functions such as mp_encode_array().

int box_tuple_ref(box_tuple_t *tuple)

Increase the reference counter of tuple.

Tuples are reference counted. All functions that return tuples guarantee that the last returned tuple is reference counted internally until the next call to API function that yields or returns another tuple.

You should increase the reference counter before taking tuples for long processing in your code. The Lua garbage collector will not destroy a tuple that has references, even if another fiber removes them from a space. After processing, decrement the reference counter using box_tuple_unref(), otherwise the tuple will leak.

Параметры:
Результат:

-1 on error
Результат:

0 otherwise

See also: box_tuple_unref()

void box_tuple_unref(box_tuple_t *tuple)

Decrease the reference counter of tuple.

Параметры:

See also: box_tuple_ref()

uint32_t box_tuple_field_count(const box_tuple_t *tuple)

Return the number of fields in a tuple (the size of MsgPack Array).

Параметры:
size_t box_tuple_bsize(const box_tuple_t *tuple)

Return the number of bytes used to store internal tuple data (MsgPack Array).

Параметры:
ssize_t box_tuple_to_buf(const box_tuple_t *tuple, char *buf, size_t size)

Dump raw MsgPack data to the memory buffer buf of size size.

Store tuple fields in the memory buffer.

Upon successful return, the function returns the number of bytes written. If buffer size is not enough then the return value is the number of bytes which would have been written if enough space had been available.

Результат:-1 on error
Результат:number of bytes written on success.
box_tuple_format_t *box_tuple_format(const box_tuple_t *tuple)

Return the associated format.

Параметры:
Результат:

tuple format
const char *box_tuple_field(const box_tuple_t *tuple, uint32_t field_id)

Return the raw tuple field in MsgPack format. The result is a pointer to raw MessagePack data which can be decoded with mp_decode functions, for an example see the tutorial program read.c.

The buffer is valid until the next call to a box_tuple_* function.

Параметры:
  • tuple (box_tuple_t*) – a tuple
  • field_id (uint32_t) – zero-based index in MsgPack array.
Результат:

NULL if i >= box_tuple_field_count()
Результат:

msgpack otherwise
enum field_type
enumerator ::FIELD_TYPE_ANY
enumerator ::FIELD_TYPE_UNSIGNED
enumerator ::FIELD_TYPE_STRING
enumerator ::FIELD_TYPE_NUMBER
enumerator ::FIELD_TYPE_DOUBLE
enumerator ::FIELD_TYPE_INTEGER
enumerator ::FIELD_TYPE_BOOLEAN
enumerator ::FIELD_TYPE_VARBINARY
enumerator ::FIELD_TYPE_SCALAR
enumerator ::FIELD_TYPE_DECIMAL
enumerator ::FIELD_TYPE_ARRAY
enumerator ::FIELD_TYPE_MAX

Possible data types for tuple fields.

One cannot use STRS/ENUM macros for types because there is a mismatch between enum name (STRING) and type name literal («STR»). STR is already used as a type in Objective C.

type box_key_def_t

Key definition

box_key_def_t *box_key_def_new(uint32_t *fields, uint32_t *types, uint32_t part_count)

Create a key definition with the key fields with passed types on passed positions.

May be used for tuple format creation and/or tuple comparison.

Параметры:
  • fields (uint32_t*) – array with key field identifiers
  • types (uint32_t) – array with key field types
  • part_count (uint32_t) – the number of key fields
Результат:

key definition on success
Результат:

NULL on error
void box_key_def_delete(box_key_def_t *key_def)

Delete a key definition

Параметры:
box_tuple_format_t *box_tuple_format_new(struct key_def *keys, uint16_t key_count)

Return new in-memory tuple format based on passed key definitions

Параметры:
  • keys (key_def) – array of keys defined for the format
  • key_count (uint16_t) – count of keys
Результат:

new tuple format on success
Результат:

NULL on error
void box_tuple_format_ref(box_tuple_format_t *format)

Increment tuple format reference count

Параметры:
void box_tuple_format_unref(box_tuple_format_t *format)

Decrement tuple format reference count

Параметры:
int box_tuple_compare(const box_tuple_t *tuple_a, const box_tuple_t *tuple_b, const box_key_def_t *key_def)

Compare tuples using key definition

Параметры:
Результат:

0 if key_fields(tuple_a) == key_fields(tuple_b)
Результат:

<0 if key_fields(tuple_a) < key_fields(tuple_b)
Результат:

>0 if key_fields(tuple_a) > key_fields(tuple_b)

See also: enum field_type

int box_tuple_compare_with_key(const box_tuple_t *tuple, const char *key, const box_key_def_t *key_def);

Compare a tuple with a key using key definition

Параметры:
  • tuple (const box_tuple_t*) – tuple
  • key (const char*) – key with MessagePack array header
  • key_def (const box_key_def_t*) – key definition
Результат:

0 if key_fields(tuple) == parts(key)
Результат:

<0 if key_fields(tuple) < parts(key)
Результат:

>0 if key_fields(tuple) > parts(key)

See also: enum field_type

type box_tuple_iterator_t

Tuple iterator

box_tuple_iterator_t *box_tuple_iterator(box_tuple_t *tuple)

Allocate and initialize a new tuple iterator. The tuple iterator allows iterating over fields at the root level of a MsgPack array.

Example:

box_tuple_iterator_t* it = box_tuple_iterator(tuple);
if (it == NULL) {
    // error handling using box_error_last()
}
const char* field;
while (field = box_tuple_next(it)) {
    // process raw MsgPack data
}

// rewind the iterator to the first position
box_tuple_rewind(it)
assert(box_tuple_position(it) == 0);

// rewind three fields
field = box_tuple_seek(it, 3);
assert(box_tuple_position(it) == 4);

box_iterator_free(it);
void box_tuple_iterator_free(box_tuple_iterator_t *it)

Destroy and free tuple iterator

uint32_t box_tuple_position(box_tuple_iterator_t *it)

Return zero-based next position in iterator. That is, this function returnы the field id of the field that will be returned by the next call to box_tuple_next(). Returned value is zero after initialization or rewind and box_tuple_field_count() after the end of iteration.

Параметры:
Результат:

position
void box_tuple_rewind(box_tuple_iterator_t *it)

Rewind iterator to the initial position.

Параметры:

After: box_tuple_position(it) == 0

const char *box_tuple_seek(box_tuple_iterator_t *it, uint32_t field_no)

Seek the tuple iterator.

The result is a pointer to raw MessagePack data which can be decoded with mp_decode functions, for an example see the tutorial program read.c. The returned buffer is valid until the next call to box_tuple_* API. The requested field_no is returned by the next call to box_tuple_next(it).

Параметры:
  • it (box_tuple_iterator_t*) – a tuple iterator
  • field_no (uint32_t) – field number - zero-based position in MsgPack array

After:

  • box_tuple_position(it) == field_not if returned value is not NULL.
  • box_tuple_position(it) == box_tuple_field_count(tuple) if returned value is NULL.
const char *box_tuple_next(box_tuple_iterator_t *it)

Return the next tuple field from tuple iterator.

The result is a pointer to raw MessagePack data which can be decoded with mp_decode functions, for an example see the tutorial program read.c. The returned buffer is valid until next call to box_tuple_* API.

Параметры:
Результат:

NULL if there are no more fields
Результат:

MsgPack otherwise

Before: box_tuple_position() is zero-based ID of returned field.

After: box_tuple_position(it) == box_tuple_field_count(tuple) if returned value is NULL.

box_tuple_t *box_tuple_update(const box_tuple_t *tuple, const char *expr, const char *expr_end)
box_tuple_t *box_tuple_upsert(const box_tuple_t *tuple, const char *expr, const char *expr_end)

Module txn

bool box_txn(void)

Return true if there is an active transaction.

int box_txn_begin(void)

Begin a transaction in the current fiber.

A transaction is attached to caller fiber, therefore one fiber can have only one active transaction. See also box.begin().

Результат:0 on success
Результат:-1 on error. Perhaps a transaction has already been started.
int box_txn_commit(void)

Commit the current transaction. See also box.commit().

Результат:0 on success
Результат:-1 on error. Perhaps a disk write failure
void box_txn_rollback(void)

Roll back the current transaction. See also box.rollback().

box_txn_savepoint_t *savepoint(void)

Return a descriptor of a savepoint.

void box_txn_rollback_to_savepoint(box_txn_savepoint_t *savepoint)

Roll back the current transaction as far as the specified savepoint.

void *box_txn_alloc(size_t size)

Allocate memory on txn memory pool.

The memory is automatically deallocated when the transaction is committed or rolled back.

Результат:NULL on out of memory

Read views: C API

Enterprise Edition

This API is available in the Enterprise Edition only.

This topic describes the C API for working with read views. The C API is MT-safe and provides the ability to use a read view from any thread, not only from the main (TX) thread.

The C API has the following specifics:

Примечание

You can learn how to call C code using stored procedures in the C tutorial.

Data types

The opaque data types below represent raw read views and an iterator over data in a raw read view. Note that there is no special data type for tuples retrieved from a read view. Tuples are returned as raw MessagePack data (const char *).

typedef box_raw_read_view box_raw_read_view_t

A raw database read view.

typedef box_raw_read_view_space box_raw_read_view_space_t

A space in a raw read view.

typedef box_raw_read_view_index box_raw_read_view_index_t

An index in a raw read view.

typedef box_raw_read_view_iterator box_raw_read_view_iterator_t

An iterator over data in a raw read view.

Creating and destroying read views

To create or destroy a read view, use the functions below.

box_raw_read_view_t *box_raw_read_view_new(const char *name)

Open a raw read view with the specified name and get a pointer to this read view. In the case of error, returns NULL and sets box_error_last(). This function may be called from the main (TX) thread only.

Параметры:
  • *name (const char) –

    (optional) a read view name; if name is not specified, a read view name is set to unknown
Результат:

a pointer to a read view
void box_raw_read_view_delete(box_raw_read_view_t *rv)

Close a raw read view and release all resources associated with it. This function may be called from the main (TX) thread only.

Параметры:

Примечание

Read views created using box_raw_read_view_new are displayed in box.read_view.list() along with read views created in Lua.

Spaces and indexes

To fetch data from a read view, you need to specify an index to fetch the data from. The following functions are available for looking up spaces and indexes in a read view object.

box_raw_read_view_space_t *box_raw_read_view_space_by_id(const box_raw_read_view_t *rv, uint32_t space_id)

Find a space by ID in a raw read view. If not found, returns NULL and sets box_error_last().

Параметры:
  • *rv (const box_raw_read_view_t) –

    a pointer to a read view

  • space_id (uint32_t) – a space identifier
Результат:

a pointer to a space
box_raw_read_view_space_t *box_raw_read_view_space_by_name(const box_raw_read_view_t *rv, const char *space_name, uint32_t space_name_len)

Find a space by name in a raw read view. If not found, returns NULL and sets box_error_last().

Параметры:
  • *rv (const box_raw_read_view_t) –

    a pointer to a read view

  • *space_name (const char) –

    a space name

  • space_name_len (uint32_t) – a space name length
Результат:

a pointer to a space
box_raw_read_view_index_t *box_raw_read_view_index_by_id(const box_raw_read_view_space_t *space, uint32_t index_id)

Find an index by ID in a read view’s space. If not found, returns NULL and sets box_error_last().

Параметры:
Результат:

a pointer to an index
box_raw_read_view_index_t *box_raw_read_view_index_by_name(const box_raw_read_view_space_t *space, const char *index_name, uint32_t index_name_len)

Find an index by name in a read view’s space. If not found, returns NULL and sets box_error_last().

Параметры:
  • *space (const box_raw_read_view_space_t) –

    a pointer to a space

  • *index_name (const char) –

    an index name

  • index_name_len (uint32_t) – an index name length
Результат:

a pointer to an index

Iteration and lookup

The functions below provide the ability to look up a tuple by the key or create an iterator over a read view index.

Примечание

Methods of the read view iterator are safe to call from any thread, but they may be used in one thread at the same time. This means that an iterator should be thread-local.

int box_raw_read_view_get(const box_raw_read_view_index_t *index, const char *key, const char *key_end, const char **data, uint32_t *size)

Look up a tuple in a read view’s index. If found, the data and size out arguments return a pointer to and the size of tuple data. If not found, *data is set to NULL and *size is set to 0.

Параметры:
  • *index (const box_raw_read_view_index_t) –

    a pointer to a read view’s index

  • *key (const char) –

    a pointer to the first byte of the MsgPack data that represents the search key

  • *key_end (const char) –

    a pointer to the byte following the last byte of the MsgPack data that represents the search key

  • **data (const char) –

    a pointer to the tuple data

  • *size (uint32_t) –

    the size of tuple data
Результат:

0 on success; in the case of error, returns -1 and sets box_error_last()
int box_raw_read_view_iterator_create(box_raw_read_view_iterator_t *it, const box_raw_read_view_index_t *index, int type, const char *key, const char *key_end)

Create an iterator over a raw read view index. The initialized iterator object returned by this function remains valid and may be safely used until it’s destroyed or the read view is closed. When the iterator object is no longer needed, it should be destroyed using box_raw_read_view_iterator_destroy().

Параметры:
  • *it (box_raw_read_view_iterator_t) –

    an iterator over a raw read view index

  • *index (const box_raw_read_view_index_t) –

    a pointer to a read view index

  • type (int) – an iteration direction represented by the iterator_type
  • *key (const char) –

    a pointer to the first byte of the MsgPack data that represents the search key

  • *key_end (const char) –

    a pointer to the byte following the last byte of the MsgPack data that represents the search key
Результат:

0 on success; in the case of error, returns -1 and sets box_error_last()
int box_raw_read_view_iterator_next(box_raw_read_view_iterator_t *it, const char **data, uint32_t *size)

Retrieve the current tuple and advance the given iterator over a raw read view index. The pointer to and the size of tuple data are returned in the data and the size out arguments. The data returned by this function remains valid and may be safely used until the read view is closed.

Параметры:
  • *it (box_raw_read_view_iterator_t) –

    an iterator over a read view index

  • **data (const char) –

    a pointer to the tuple data; at the end of iteration, *data is set to NULL

  • *size (uint32_t) –

    the size of tuple data; at the end of iteration, *size is set to 0
Результат:

0 on success; in the case of error, returns -1 and sets box_error_last()
void box_raw_read_view_iterator_destroy(box_raw_read_view_iterator_t *it)

Destroy an iterator over a raw read view index. The iterator object should not be used after calling this function, but the data returned by the iterator may be safely dereferenced until the read view is closed.

Параметры:

Space format

A space object’s methods below provide the ability to get names and types of space fields.

uint32_t box_raw_read_view_space_field_count(const box_raw_read_view_space_t *space)

Get the number of fields defined in the format of a read view space.

Параметры:
Результат:

the number of fields
const char *box_raw_read_view_space_field_name(const box_raw_read_view_space_t *space, uint32_t field_no)

Get the name of a field defined in the format of a read view space. If the field number is greater than the total number of fields defined in the format, NULL is returned. The string returned by this function is guaranteed to remain valid until the read view is closed.

Параметры:
  • *space (const box_raw_read_view_space_t) –

    a pointer to a read view space

  • field_no (uint32_t) – the field number (starts with 0)
Результат:

the name of a field
const char *box_raw_read_view_space_field_type(const box_raw_read_view_space_t *space, uint32_t field_no)

Get the type of a field defined in the format of a read view space. If the field number is greater than the total number of fields defined in the format, NULL is returned. The string returned by this function is guaranteed to remain valid until the read view is closed.

Параметры:
  • *space (const box_raw_read_view_space_t) –

    a pointer to a read view space

  • field_no (uint32_t) – the field number (starts with 0)
Результат:

the type of a field

Internals

Binary protocol

This section provides information on the Tarantool binary protocol, iproto. The protocol is called «binary» because the database is most frequently accessed via binary code instead of Lua request text. Tarantool experts use it:

The binary protocol provides complete access to Tarantool functionality, including:

Примечание

Since version 2.11.0, you can use the box.iproto submodule to access IPROTO constants and features from Lua. The submodule enables to send arbitrary IPROTO packets over the session’s socket and override the behavior for all IPROTO request types. Also, IPROTO_UNKNOWN constant is introduced. The constant is used for the box.iproto.override() API, which allows setting a handler for incoming requests with an unknown type.

Understanding the binary protocol

Overview

To communicate with each other, Tarantool instances use a binary protocol called iproto.

In this set of examples, the user will be looking at binary code transferred via iproto. The code is intercepted with tcpdump, a monitoring utility.

Examples

To follow the examples in this section, get a single Linux computer and start three command-line shells («terminals»).

– On terminal #1, Start monitoring port 3302 with tcpdump: 

sudo tcpdump -i lo 'port 3302' -X

On terminal #2, start a server with:

box.cfg{listen=3302}
box.schema.space.create('tspace')
box.space.tspace:create_index('I')
box.space.tspace:insert{280}
box.schema.user.grant('guest','read,write,execute,create,drop','universe')

On terminal #3, start another server, which will act as a client, with:

box.cfg{}
net_box = require('net.box')
conn = net_box.connect('localhost:3302')

IPROTO_SELECT

On terminal #3, run the following:

conn.space.tspace:select(280)

Now look at what tcpdump shows for the job connecting to 3302 – the «request». After the words «length 32» is a packet that ends with these 32 bytes (we have added indented comments):

ce 00 00 00 1b   MP_UINT = decimal 27 = number of bytes after this
82               MP_MAP, size 2 (we'll call this "Main-Map")
01                 IPROTO_SYNC (Main-Map Item#1)
04                 MP_INT = 4 = number that gets incremented with each request
00                 IPROTO_REQUEST_TYPE (Main-Map Item#2)
01                 IPROTO_SELECT
86                 MP_MAP, size 6 (we'll call this "Select-Map")
10                   IPROTO_SPACE_ID (Select-Map Item#1)
cd 02 00             MP_UINT = decimal 512 = id of tspace (could be larger)
11                   IPROTO_INDEX_ID (Select-Map Item#2)
00                   MP_INT = 0 = id of index within tspace
14                   IPROTO_ITERATOR (Select-Map Item#3)
00                   MP_INT = 0 = Tarantool iterator_type.h constant ITER_EQ
13                   IPROTO_OFFSET (Select-Map Item#4)
00                   MP_INT = 0 = amount to offset
12                   IPROTO_LIMIT (Select-Map Item#5)
ce ff ff ff ff       MP_UINT = 4294967295 = biggest possible limit
20                   IPROTO_KEY (Select-Map Item#6)
91                   MP_ARRAY, size 1 (we'll call this "Key-Array")
cd 01 18               MP_UINT = 280 (Select-Map Item#6, Key-Array Item#1)
                       -- 280 is the key value that we are searching for

Now read the source code file net_box.c and skip to the line netbox_encode_select(lua_State *L). From the comments and from simple function calls like mpstream_encode_uint(&stream, IPROTO_SPACE_ID); you will be able to see how net_box put together the packet contents that you have just observed with tcpdump.

There are libraries for reading and writing MessagePack objects. C programmers sometimes include msgpuck.h.

Now you know how Tarantool itself makes requests with the binary protocol. When in doubt about a detail, consult net_box.c – it has routines for each request. Some connectors have similar code.

IPROTO_UPDATE

For an IPROTO_UPDATE example, suppose a user changes field #2 in tuple #2 in space #256 to 'BBBB'. The body will look like this: (notice that in this case there is an extra map item IPROTO_INDEX_BASE, to emphasize that field numbers start with 1, which is optional and can be omitted):

04               IPROTO_UPDATE
85               IPROTO_MAP, size 5
10                 IPROTO_SPACE_ID, Map Item#1
cd 02 00           MP_UINT 256
11                 IPROTO_INDEX_ID, Map Item#2
00                 MP_INT 0 = primary-key index number
15                 IPROTO_INDEX_BASE, Map Item#3
01                 MP_INT = 1 i.e. field numbers start at 1
21                 IPROTO_TUPLE, Map Item#4
91                 MP_ARRAY, size 1, for array of operations
93                   MP_ARRAY, size 3
a1 3d                   MP_STR = OPERATOR = '='
02                      MP_INT = FIELD_NO = 2
a5 42 42 42 42 42       MP_STR = VALUE = 'BBBB'
20                 IPROTO_KEY, Map Item#5
91                 MP_ARRAY, size 1, for array of key values
02                   MP_UINT = primary-key value = 2

IPROTO_EXECUTE

Byte codes for the IPROTO_EXECUTE example:

0b               IPROTO_EXECUTE
83               MP_MAP, size 3
43                 IPROTO_STMT_ID Map Item#1
ce d7 aa 74 1b     MP_UINT value of n.stmt_id
41                 IPROTO_SQL_BIND Map Item#2
92                 MP_ARRAY, size 2
01                   MP_INT = 1 = value for first parameter
a1 61                MP_STR = 'a' = value for second parameter
2b                 IPROTO_OPTIONS Map Item#3
90                 MP_ARRAY, size 0 (there are no options)

IPROTO_INSERT

Byte codes for the response to the box.space.space-name:insert{6} example:

ce 00 00 00 20                MP_UINT = HEADER AND BODY SIZE
83                            MP_MAP, size 3
00                              IPROTO_REQUEST_TYPE
ce 00 00 00 00                  MP_UINT = IPROTO_OK
01                              IPROTO_SYNC
cf 00 00 00 00 00 00 00 53      MP_UINT = sync value
05                              IPROTO_SCHEMA_VERSION
ce 00 00 00 68                  MP_UINT = schema version
81                            MP_MAP, size 1
30                              IPROTO_DATA
dd 00 00 00 01                  MP_ARRAY, size 1 (row count)
91                              MP_ARRAY, size 1 (field count)
06                              MP_INT = 6 = the value that was inserted

IPROTO_EVAL

Byte codes for the response to the conn:eval([[box.schema.space.create('_space');]]) example:

ce 00 00 00 3b                  MP_UINT = HEADER AND BODY SIZE
83                              MP_MAP, size 3 (i.e. 3 items in header)
   00                              IPROTO_REQUEST_TYPE
   ce 00 00 80 0a                  MP_UINT = hexadecimal 800a
   01                              IPROTO_SYNC
   cf 00 00 00 00 00 00 00 26      MP_UINT = sync value
   05                              IPROTO_SCHEMA_VERSION
   ce 00 00 00 78                  MP_UINT = schema version value
   81                              MP_MAP, size 1
     31                              IPROTO_ERROR_24
     db 00 00 00 1d 53 70 61 63 etc. MP_STR = "Space '_space' already exists"

Creating a table with IPROTO_EXECUTE

Byte codes, if we use the same net.box connection that we used in the beginning and we say
conn:execute([[CREATE TABLE t1 (dd INT PRIMARY KEY AUTOINCREMENT, дд STRING COLLATE "unicode");]])
conn:execute([[INSERT INTO t1 VALUES (NULL, 'a'), (NULL, 'b');]])
and we watch what tcpdump displays, we will see two noticeable things: (1) the CREATE statement caused a schema change so the response has a new IPROTO_SCHEMA_VERSION value and the body includes the new contents of some system tables (caused by requests from net.box which users will not see); (2) the final bytes of the response to the INSERT will be:

81   MP_MAP, size 1
42     IPROTO_SQL_INFO
82     MP_MAP, size 2
00       Tarantool constant (not in iproto_constants.h) = SQL_INFO_ROW_COUNT
02       1 = row count
01       Tarantool constant (not in iproto_constants.h) = SQL_INFO_AUTOINCREMENT_ID
92       MP_ARRAY, size 2
01         first autoincrement number
02         second autoincrement number

SELECT with SQL

Byte codes for the SQL SELECT example, if we ask for full metadata by saying
conn.space._session_settings:update('sql_full_metadata', {{'=', 'value', true}})
and we select the two rows from the table that we just created
conn:execute([[SELECT dd, дд AS д FROM t1;]])
then tcpdump will show this response, after the header:

82                       MP_MAP, size 2 (i.e. metadata and rows)
32                         IPROTO_METADATA
92                         MP_ARRAY, size 2 (i.e. 2 columns)
85                           MP_MAP, size 5 (i.e. 5 items for column#1)
00 a2 44 44                    IPROTO_FIELD_NAME and 'DD'
01 a7 69 6e 74 65 67 65 72     IPROTO_FIELD_TYPE and 'integer'
03 c2                          IPROTO_FIELD_IS_NULLABLE and false
04 c3                          IPROTO_FIELD_IS_AUTOINCREMENT and true
05 c0                          PROTO_FIELD_SPAN and nil
85                           MP_MAP, size 5 (i.e. 5 items for column#2)
00 a2 d0 94                    IPROTO_FIELD_NAME and 'Д' upper case
01 a6 73 74 72 69 6e 67        IPROTO_FIELD_TYPE and 'string'
02 a7 75 6e 69 63 6f 64 65     IPROTO_FIELD_COLL and 'unicode'
03 c3                          IPROTO_FIELD_IS_NULLABLE and true
05 a4 d0 b4 d0 b4              IPROTO_FIELD_SPAN and 'дд' lower case
30                         IPROTO_DATA
92                         MP_ARRAY, size 2
92                           MP_ARRAY, size 2
01                             MP_INT = 1 i.e. contents of row#1 column#1
a1 61                          MP_STR = 'a' i.e. contents of row#1 column#2
92                           MP_ARRAY, size 2
02                             MP_INT = 2 i.e. contents of row#2 column#1
a1 62                          MP_STR = 'b' i.e. contents of row#2 column#2

IPROTO_PREPARE

Byte code for the SQL PREPARE example. If we said
conn:prepare([[SELECT dd, дд AS д FROM t1;]])
then tcpdump would show almost the same response, but there would be no IPROTO_DATA. Instead, additional items will appear:

34                       IPROTO_BIND_COUNT
00                       MP_UINT = 0

33                       IPROTO_BIND_METADATA
90                       MP_ARRAY, size 0

MP_UINT = 0 and MP_ARRAY has size 0 because there are no parameters to bind. Full output:

84                       MP_MAP, size 4
43                         IPROTO_STMT_ID
ce c2 3c 2c 1e             MP_UINT = statement id
34                         IPROTO_BIND_COUNT
00                         MP_INT = 0 = number of parameters to bind
33                         IPROTO_BIND_METADATA
90                         MP_ARRAY, size 0 = there are no parameters to bind
32                         IPROTO_METADATA
92                         MP_ARRAY, size 2 (i.e. 2 columns)
85                           MP_MAP, size 5 (i.e. 5 items for column#1)
00 a2 44 44                    IPROTO_FIELD_NAME and 'DD'
01 a7 69 6e 74 65 67 65 72     IPROTO_FIELD_TYPE and 'integer'
03 c2                          IPROTO_FIELD_IS_NULLABLE and false
04 c3                          IPROTO_FIELD_IS_AUTOINCREMENT and true
05 c0                          PROTO_FIELD_SPAN and nil
85                           MP_MAP, size 5 (i.e. 5 items for column#2)
00 a2 d0 94                    IPROTO_FIELD_NAME and 'Д' upper case
01 a6 73 74 72 69 6e 67        IPROTO_FIELD_TYPE and 'string'
02 a7 75 6e 69 63 6f 64 65     IPROTO_FIELD_COLL and 'unicode'
03 c3                          IPROTO_FIELD_IS_NULLABLE and true
05 a4 d0 b4 d0 b4              IPROTO_FIELD_SPAN and 'дд' lower case

Heartbeat

Byte code for the heartbeat example. The master might send this body:

83                      MP_MAP, size 3
00                        Main-Map Item #1 IPROTO_REQUEST_TYPE
00                          MP_UINT = 0
02                        Main-Map Item #2 IPROTO_REPLICA_ID
02                          MP_UINT = 2 = id
04                        Main-Map Item #3 IPROTO_TIMESTAMP
cb                          MP_DOUBLE (MessagePack "Float 64")
41 d7 ba 06 7b 3a 03 21     8-byte timestamp
81                      MP_MAP (body), size 1
5a                      Body Map Item #1 IPROTO_VCLOCK_SYNC
14                        MP_UINT = 20 (vclock sync value)

Byte code for the heartbeat example. The replica might send back this body:

81                       MP_MAP, size 1
00                         Main-Map Item #1 IPROTO_REQUEST_TYPE
00                         MP_UINT = 0 = IPROTO_OK
83                         MP_MAP (body), size 3
26                           Body Map Item #1 IPROTO_VCLOCK
81                             MP_MAP, size 1 (vclock of 1 component)
01                               MP_UINT = 1 = id (part 1 of vclock)
06                               MP_UINT = 6 = lsn (part 2 of vclock)
5a                           Body Map Item #2 IPROTO_VCLOCK_SYNC
14                             MP_UINT = 20 (vclock sync value)
53                           Body Map Item #3 IPROTO_TERM
31                             MP_UINT = 49 (term value)

MP_* MessagePack types

The binary protocol handles data in the MessagePack format. Short descriptions of the basic MessagePack data types are on MessagePack’s specification page. Tarantool also introduces several MessagePack type extensions.

In this document, MessagePack types are described by words that start with MP_. See this table:

MP_NIL nil
MP_UINT unsigned integer
MP_INT either integer or unsigned integer
MP_STR string
MP_BIN binary string
MP_ARRAY array
MP_MAP map
MP_BOOL boolean
MP_FLOAT float
MP_DOUBLE double
MP_EXT extension
MP_OBJECT any MessagePack object

Request and response format

The types referred to in this document are MessagePack types. For their definitions, see the MP_* MessagePack types section.

Packet structure

Requests and responses have similar structure. They contain three sections: size, header, and body.

PacketsizeMP_UINTheaderMP_MAPbodyMP_MAP

It is legal to put more than one request in a packet.

Size

The size is an MP_UINT – unsigned integer, usually 32-bit. It is the size of the header plus the size of the body. It may be useful to compare it with the number of bytes remaining in the packet.

Body

The body is an MP_MAP. Maximal iproto package body length is 2 GiB.

The body has the details of the request or response. In a request, it can also be absent or be an empty map. Both these states are interpreted equally. Responses contain the body anyway even for an IPROTO_PING request, where it is an empty MP_MAP.

A lot of responses contain the IPROTO_DATA map:

BodyIPROTO_DATAMP_OBJECT

For most data-access requests (IPROTO_SELECT, IPROTO_INSERT, IPROTO_DELETE, etc.) the body is an IPROTO_DATA map with an array of tuples that contain an array of fields.

IPROTO_DATA is what we get with net_box and Module buffer so if we were using net_box we could decode with msgpack.decode_unchecked(), or we could convert to a string with ffi.string(pointer,length). The pickle.unpack() function might also be helpful.

Примечание

For SQL-specific requests and responses, the body is a bit different. Learn more about this type of packets.

Error responses

Instead of IPROTO_OK, an error response header has IPROTO_REQUEST_TYPE = IPROTO_TYPE_ERROR. Its code is 0x8XXX, where XXX is the error code – a value in src/box/errcode.h. src/box/errcode.h also has some convenience macros which define hexadecimal constants for return codes.

The error response body is a map that contains two keys: IPROTO_ERROR and IPROTO_ERROR_24. While IPROTO_ERROR contains an MP_MAP value, IPROTO_ERROR_24 contains a string. The two keys are provided to accommodate clients with older and newer Tarantool versions.

Error responseSizeMP_UINTHeaderIPROTO_REQUEST_TYPE0x8XXXIPROTO_SYNCMP_UINTIPROTO_SCHEMA_VERSIONMP_UINTBodyIPROTO_ERRORMP_ERRORIPROTO_ERROR_24MP_STR

Error responses before 2.4.1

Before Tarantool v. 2.4.1, the key IPROTO_ERROR contained a string and was identical to the current IPROTO_ERROR_24 key.

Let’s consider an example. This is the fifth message, and the request was to create a duplicate space with conn:eval([[box.schema.space.create('_space');]]). The unsuccessful response looks like this:

Error response before 2.4.1Size32HeaderIPROTO_REQUEST_TYPE0x800aIPROTO_SYNC5IPROTO_SCHEMA_VERSION0x78BodyIPROTO_ERRORSpace '_space' already exists

The tutorial Understanding the binary protocol shows actual byte codes of the response to the IPROTO_EVAL message.

Looking in errcode.h, we find that the error code 0x0a (decimal 10) is ER_SPACE_EXISTS, and the string associated with ER_SPACE_EXISTS is «Space „%s“ already exists».

Since version 2.4.1, responses for errors have extra information following what was described above. This extra information is given via the MP_ERROR extension type. See details in the MessagePack extensions section.

Keys used in requests and responses

This section describes iproto keys contained in requests and responses. The keys are Tarantool constants that are either defined or mentioned in the iproto_constants.h file.

While the keys themselves are unsigned 8-bit integers, their values can have different types.

Basic description

General

Name Code and
value type		 Description
IPROTO_VERSION 0x54
MP_UINT		 Binary protocol version supported by the client
IPROTO_FEATURES 0x55
MP_ARRAY		 Supported binary protocol features
IPROTO_SYNC 0x01
MP_UINT		 Unique request identifier
IPROTO_SCHEMA_VERSION 0x05
MP_UINT		 Version of the database schema
IPROTO_TIMESTAMP 0x04
MP_DOUBLE		 Time in seconds since the Unix epoch
IPROTO_REQUEST_TYPE 0x00
MP_UINT		 Request type or response type
IPROTO_ERROR 0x52
MP_ERROR		 Error response
IPROTO_ERROR_24 0x31
MP_STR		 Error as a string
IPROTO_DATA 0x30
MP_OBJECT		 Data passed in the transaction. Can be empty. Used in all requests and responses
IPROTO_SPACE_ID 0x10
MP_UINT		 Space identifier
IPROTO_INDEX_ID 0x11
MP_UINT		 Index identifier
IPROTO_TUPLE 0x21
MP_ARRAY		 Tuple, arguments, operations, or authentication pair. See details
IPROTO_KEY 0x20
MP_ARRAY		 Array of index keys in the request. See space_object:select()
IPROTO_LIMIT 0x12
MP_UINT		 Maximum number of tuples in the space
IPROTO_OFFSET 0x13
MP_UINT		 Number of tuples to skip in the select
IPROTO_ITERATOR 0x14
MP_UINT		 Iterator type
IPROTO_INDEX_BASE 0x15
MP_UINT		 Indicates whether the first field number is 1 or 0
IPROTO_FUNCTION_NAME 0x22
MP_STR		 Name of the called function. Used in IPROTO_CALL
IPROTO_USER_NAME 0x23
MP_STR		 User name. Used in IPROTO_AUTH
IPROTO_OPS 0x28
MP_ARRAY		 Array of operations. Used in IPROTO_UPSERT
IPROTO_EXPR 0x27
MP_STR		 Command argument. Used in IPROTO_EVAL
IPROTO_AUTH_TYPE 0x5b
MP_STR		 A protocol used to generate user authentication data
IPROTO_AFTER_POSITION 0x2e
MP_STR		 The position of a tuple after which space_object:select() starts the search
IPROTO_AFTER_TUPLE 0x2f
MP_ARRAY		 A tuple after which space_object:select() starts the search
IPROTO_FETCH_POSITION 0x1f
MP_BOOL		 If true, space_object:select() returns the position of the last selected tuple
IPROTO_POSITION 0x35
MP_STR		 If IPROTO_FETCH_POSITION is true, returns a base64-encoded string representing the position of the last selected tuple

Streams

Name Code and
value type		 Description
IPROTO_STREAM_ID 0x0a
MP_UINT		 Unique stream identifier
IPROTO_TIMEOUT 0x56
MP_DOUBLE		 Timeout in seconds, after which the transactions are rolled back
IPROTO_TXN_ISOLATION 0x59
MP_UINT		 Transaction isolation level

General replication

Name Code and
value type		 Description
IPROTO_REPLICA_ID 0x02
MP_INT		 Replica ID
IPROTO_INSTANCE_UUID 0x24
MP_STR		 Instance UUID
IPROTO_VCLOCK 0x26
MP_MAP		 The instance’s vclock
IPROTO_VCLOCK_SYNC 0x5a
MP_UINT		 ID of the vclock synchronization request. Since 2.11
IPROTO_REPLICASET_UUID 0x25
MP_STR		 Before Tarantool version 2.11, IPROTO_REPLICASET_UUID was called IPROTO_CLUSTER_UUID.
IPROTO_LSN 0x03
MP_UINT		 Log sequence number of the transaction
IPROTO_TSN 0x08
MP_UINT		 Transaction sequence number
IPROTO_BALLOT_IS_RO_CFG 0x01
MP_BOOL		 True if the instance is configured as read_only. Since 2.6.1
IPROTO_BALLOT_VCLOCK 0x02
MP_MAP		 Current vclock of the instance
IPROTO_BALLOT_GC_VCLOCK 0x03
MP_MAP		 Vclock of the instance’s oldest WAL entry
IPROTO_BALLOT_IS_RO 0x04
MP_BOOL		 True if the instance is not writable: configured as read_only, has orphan status, or is a Raft follower. Since 2.6.1
IPROTO_BALLOT_IS_ANON 0x05
MP_BOOL		 True if the replica is anonymous. Corresponds to replication.anon. Since 2.7.1
IPROTO_BALLOT_IS_BOOTED 0x06
MP_BOOL		 True if the instance has finished its bootstrap or recovery process. Since 2.7.3, 2.8.2, 2.10.0
IPROTO_BALLOT_CAN_LEAD 0x07
MP_BOOL		 True if box.cfg.election_mode is candidate or manual. Since v. 2.7.3 and 2.8.2
IPROTO_BALLOT_BOOTSTRAP_LEADER_UUID 0x08
MP_STR		 UUID of the bootstrap leader. The UUID is encoded as a 36-byte string. Since v. 2.11
IPROTO_BALLOT_REGISTERED_REPLICA_UUIDS 0x09
MP_ARRAY		 An array of MP_STR elements that contains the UUIDs of members registered in the replica set. Each UUID is encoded as a 36-byte string. Since v. 2.11
IPROTO_FLAGS 0x09
MP_UINT		 Auxiliary data to indicate the last transaction message state. Included in the header of any DML request that is recorded in the WAL.
IPROTO_SERVER_VERSION 0x06
MP_UINT		 Tarantool version of the subscribing node, in a compact representation
IPROTO_REPLICA_ANON 0x50
MP_BOOL		 Optional key used in SUBSCRIBE request. True if the subscribing replica is anonymous
IPROTO_ID_FILTER 0x51
MP_ARRAY		 Optional key used in SUBSCRIBE request, followed by an array of ids of instances whose rows won’t be relayed to the replica. Since v. 2.10.0

Synchronous replication

Name Code and
value type		 Description
IPROTO_TERM 0x53
MP_UINT		 RAFT term on an instance
IPROTO_RAFT_TERM 0x00
MP_UINT		 RAFT term on an instance. The key is only used for requests with the IPROTO_RAFT type.
IPROTO_RAFT_VOTE 0x01
MP_UINT		 Instance vote in the current term (if any)
IPROTO_RAFT_STATE 0x02
MP_UINT		 RAFT state. Possible values: 1 – follower, 2 – candidate, 3 – leader
IPROTO_RAFT_VCLOCK 0x03
MP_MAP		 Current vclock of the instance
IPROTO_RAFT_LEADER_ID 0x04
MP_UINT		 Current leader node ID as seen by the node that issues the request Since version 2.10.0
IPROTO_RAFT_IS_LEADER_SEEN 0x05
MP_BOOL		 True if the node has a direct connection to the leader node. Since version 2.10.0

All IPROTO_RAFT_* keys are used only in IPROTO_RAFT* requests.

Events and subscriptions

Name Code and
value type		 Description
IPROTO_EVENT_KEY 0x57
MP_STR		 Event key name
IPROTO_EVENT_DATA 0x58
MP_OBJECT		 Event data sent to a remote watcher

Learn more about events and subscriptions in iproto.

SQL-specific

These keys are used with SQL within SQL-specific requests and responses like IPROTO_EXECUTE and IPROTO_PREPARE.

Name Code and
value type		 Description
IPROTO_SQL_TEXT 0x40
MP_STR		 SQL statement text
IPROTO_STMT_ID 0x43
MP_INT		 Identifier of the prepared statement
IPROTO_OPTIONS 0x2b
MP_ARRAY		 SQL transaction options. Usually empty
IPROTO_METADATA 0x32
MP_ARRAY of MP_MAP items		 SQL transaction metadata
IPROTO_FIELD_NAME 0x00
MP_STR		 Field name. Nested in IPROTO_METADATA
IPROTO_FIELD_TYPE 0x01
MP_STR		 Field type. Nested in IPROTO_METADATA
IPROTO_FIELD_COLL 0x02
MP_STR		 Field collation. Nested in IPROTO_METADATA
IPROTO_FIELD_IS_NULLABLE 0x03
MP_BOOL		 True if the field is nullable. Nested in IPROTO_METADATA.
IPROTO_FIELD_IS_AUTOINCREMENT 0x04
MP_BOOL		 True if the field is auto-incremented. Nested in IPROTO_METADATA.
IPROTO_FIELD_SPAN 0x05
MP_STR or MP_NIL		 Original expression under SELECT. Nested in IPROTO_METADATA. See box.execute()
IPROTO_BIND_METADATA 0x33
MP_ARRAY		 Bind variable names and types
IPROTO_BIND_COUNT 0x34
MP_INT		 Number of parameters to bind
IPROTO_SQL_BIND 0x41
MP_ARRAY		 Parameter values to match ? placeholders or :name placeholders
IPROTO_SQL_INFO 0x42
MP_MAP		 Additional SQL-related parameters
SQL_INFO_ROW_COUNT 0x00
MP_UINT		 Number of changed rows. Is 0 for statements that do not change rows. Nested in IPROTO_SQL_INFO
SQL_INFO_AUTO_INCREMENT_IDS 0x01
MP_ARRAY of MP_UINT items		 New primary key value (or values) for an INSERT in a table defined with PRIMARY KEY AUTOINCREMENT. Nested in IPROTO_SQL_INFO

Details on individual keys

IPROTO_VERSION

Code: 0x54.

IPROTO_VERSION is an integer number reflecting the version of protocol that the client supports. The latest IPROTO_VERSION is 3.

IPROTO_FEATURES

Code: 0x55.

Available IPROTO_FEATURES are the following:

IPROTO_SYNC

Code: 0x01.

This is an unsigned integer that should be incremented so that it is unique in every request. This integer is also returned from box.session.sync().

The IPROTO_SYNC value of a response should be the same as the IPROTO_SYNC value of a request.

IPROTO_SCHEMA_VERSION

Code: 0x05.

Version of the database schema – an unsigned number that goes up when there is a major change in the schema.

In a request header, IPROTO_SCHEMA_VERSION is optional, so the version will not be checked if it is absent.

In a response header, IPROTO_SCHEMA_VERSION is always present, and it is up to the client to check if it has changed.

IPROTO_ITERATOR

Code: 0x14.

Possible values (see iterator_type.h):

0 EQ
1 REQ
2 ALL, all tuples
3 LT, less than
4 LE, less than or equal
5 GE, greater than or equal
6 GT, greater than
7 BITS_ALL_SET, all bits of the value are set in the key
8 BITS_ANY_SET, at least one bit of the value is set
9 BITS_ALL_NOT_SET, no bits are set
10 OVERLAPS, overlaps the rectangle or box
11 NEIGHBOR, neighbors the rectangle or box

IPROTO_STREAM_ID

Code: 0x0a.

Only used in streams. This is an unsigned number that should be unique in every stream.

In requests, IPROTO_STREAM_ID is useful for two things: ensuring that requests within transactions are done in separate groups, and ensuring strictly consistent execution of requests (whether or not they are within transactions).

In responses, IPROTO_STREAM_ID does not appear.

See Binary protocol – streams.

IPROTO_TXN_ISOLATION

IPROTO_TXN_ISOLATION is the transaction isolation level. It can take the following values:

  • TXN_ISOLATION_DEFAULT = 0 – use the default level from box.cfg (default value)
  • TXN_ISOLATION_READ_COMMITTED = 1 – read changes that are committed but not confirmed yet
  • TXN_ISOLATION_READ_CONFIRMED = 2 – read confirmed changes
  • TXN_ISOLATION_BEST_EFFORT = 3 – determine isolation level automatically

See Binary protocol – streams to learn more about stream transactions in the binary protocol.

IPROTO_REQUEST_TYPE

Code: 0x00.

The key is used both in requests and responses. It indicates the request or response type and has any request or response name for the value (example: IPROTO_AUTH). See requests and responses for client-server communication, replication, events and subscriptions, streams and interactive transactions.

IPROTO_ERROR

Code: 0x52.

In case of error, the response body contains IPROTO_ERROR and IPROTO_ERROR_24 instead of IPROTO_DATA.

To learn more about error responses, check the section Request and response format.

IPROTO_ERROR_24

Code: 0x31.

IPROTO_ERROR_24 is used in Tarantool versions before 2.4.1. The key contains the error in the string format.

Since Tarantool 2.4.1, Tarantool packs errors as the MP_ERROR MessagePack extension, which includes extra information. Two keys are passed in the error response body: IPROTO_ERROR and IPROTO_ERROR_24.

To learn more about error responses, check the section Request and response format.

IPROTO_TUPLE

Code: 0x21.

Multiple operations make use of this key in different ways:

IPROTO_INSERT, IPROTO_REPLACE, IPROTO_UPSERT Tuple to be inserted
IPROTO_UPSERT Operations to perform
IPROTO_AUTH Array of 2 fields: authentication mechanism and scramble, encrypted according to the specified mechanism. See more on the authentication sequence.
IPROTO_CALL, IPROTO_EVAL Array of arguments

IPROTO_FLAGS

Code: 0x09.

When it comes to replicating synchronous transactions, the IPROTO_FLAGS key is included in the header. The key contains an MP_UINT value of one or more bits:

  • IPROTO_FLAG_COMMIT (0x01) is set if this is the last message for a transaction.
  • IPROTO_FLAG_WAIT_SYNC (0x02) is set if this is the last message for a transaction which cannot be completed immediately.
  • IPROTO_FLAG_WAIT_ACK (0x04) is set if this is the last message for a synchronous transaction.

Example:

Example of IPROTO_FLAGS usageSizeMP_UINTHeader............IPROTO_FLAGSMP_UINTBody...

IPROTO_TERM

Code: 0x53.

Vclock keys

The vclock (vector clock) is a log sequence number map that defines the version of the dataset stored on the node. In fact, it represents the number of logical operations executed on a specific node. A vclock looks like this:

vclockreplica_id1LSN1replica_id2LSN2......

There are five keys that correspond to vector clocks in different contexts of replication. They all have the MP_MAP type:

  • IPROTO_VCLOCK (0x26) is passed to a new instance joining the replica set.
  • IPROTO_VCLOCK_SYNC (0x5a) is used by replication heartbeats. The master sends its heartbeats, including this monotonically growing key, to a replica. Once the replica receives a heartbeat with a non-zero IPROTO_VCLOCK_SYNC value, it starts responding with the same value in all its acknowledgements. This key was introduced in version 2.11.
  • IPROTO_BALLOT_VCLOCK (0x02) is included in the IPROTO_BALLOT message. IPROTO_BALLOT is sent in response to the IPROTO_VOTE request. This key was introduced in Tarantool 2.6.1.
  • IPROTO_BALLOT_GC_VCLOCK (0x03) is also included in the IPROTO_BALLOT message. IPROTO_BALLOT is sent in response to the IPROTO_VOTE request. It is the vclock of the oldest WAL entry on the instance. Corresponds to box.info.gc().vclock. This key was introduced in Tarantool 2.6.1.
  • IPROTO_RAFT_VCLOCK (0x03) is included in the IPROTO_RAFT message. It is present only on the instances in the «candidate» state (IPROTO_RAFT_STATE == 2).

IPROTO_BALLOT keys

All IPROTO_BALLOT_* keys are only used in the IPROTO_BALLOT requests. There have been the following name changes starting with versions Tarantool 2.7.3, Tarantool 2.8.2, and Tarantool 2.10.0:

  • IPROTO_BALLOT_IS_RO_CFG (0x01) was formerly called IPROTO_BALLOT_IS_RO.
  • IPROTO_BALLOT_IS_RO (0x04) was formerly called IPROTO_BALLOT_IS_LOADING.

IPROTO_METADATA

Code: 0x32.

Used with SQL within IPROTO_EXECUTE.

The key contains an array of column maps, with each column map containing at least IPROTO_FIELD_NAME (0x00) and MP_STR, and IPROTO_FIELD_TYPE (0x01) and MP_STR.

Additionally, if sql_full_metadata in the _session_settings system space is TRUE, then the array has these additional column maps which correspond to components described in the box.execute() section.

IPROTO_SQL_BIND

Code: 0x41.

Used with SQL within IPROTO_EXECUTE.

IPROTO_SQL_BIND is an array of parameter values to match ? placeholders or :name placeholders. It can contain values of any type, including MP_MAP.

  • Values that are not MP_MAP replace the ? placeholders in the request.

  • MP_MAP values must have the format {[name] = value}, where name is the named parameter in the request. Here is an example of such a request:

    tarantool> conn:execute('SELECT ?, ?, :name1, ?, :name2, :name1', {1, 2, {[':name1'] = 5}, 'str', {[':name2'] = true}})
---
- metadata:
- name: COLUMN_1
    type: integer
- name: COLUMN_2
    type: integer
- name: COLUMN_3
    type: integer
- name: COLUMN_4
    type: text
- name: COLUMN_5
    type: boolean
- name: COLUMN_6
    type: boolean
rows:
- [1, 2, 5, 'str', true, 5]

Client-server requests and responses

This section describes client requests, their arguments, and the values returned by the server.

Some requests are described on separate pages. Those are the requests related to:

Overview

Name Code Description
IPROTO_OK 0x00
MP_UINT		 Successful response
IPROTO_CHUNK 0x80
MP_UINT		 Out-of-band response
IPROTO_TYPE_ERROR 0x8XXX
MP_INT		 Error response
IPROTO_UNKNOWN -1
MP_UINT		 An unknown request type
IPROTO_SELECT 0x01 Select request
IPROTO_INSERT 0x02 Insert request
IPROTO_REPLACE 0x03 Replace request
IPROTO_UPDATE 0x04 Update request
IPROTO_UPSERT 0x09 Upsert request
IPROTO_DELETE 0x05 Delete request
IPROTO_CALL 0x0a Function remote call (conn:call())
IPROTO_AUTH 0x07 Authentication request
IPROTO_EVAL 0x08 Evaluate a Lua expression (conn:eval())
IPROTO_NOP 0x0c Increment the LSN and do nothing else
IPROTO_PING 0x40 Ping (conn:ping())
IPROTO_ID 0x49 Share iproto version and supported features

IPROTO_OK

Code: 0x00.

This request/response type is contained in the header and signifies success. Here is an example:

Example of IPROTO_OK usageSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_OKIPROTO_SYNCMP_UINTIPROTO_SCHEMA_VERSIONMP_UINTBodyIPROTO_DATAMP_OBJECT

IPROTO_CHUNK

Code: 0x80.

If the response is out-of-band, due to use of box.session.push(), then IPROTO_REQUEST_TYPE is IPROTO_CHUNK instead of IPROTO_OK.

IPROTO_TYPE_ERROR

Code: 0x8XXX (see below).

Instead of IPROTO_OK, an error response header has 0x8XXX for IPROTO_REQUEST_TYPE. XXX is the error code – a value in src/box/errcode.h. src/box/errcode.h also has some convenience macros which define hexadecimal constants for return codes.

To learn more about error responses, check the section Request and response format.

IPROTO_UNKNOWN

Since 2.11.0.

Code: -1.

An unknown request type. The constant is used to override the handler of unknown IPROTO request types. Learn more: box.iproto.override() and box_iproto_override.

IPROTO_SELECT

Code: 0x01.

See space_object:select(). The body is a 6-item map.

IPROTO_SELECTSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_SELECTIPROTO_SYNCMP_UINTBodyIPROTO_SPACE_IDMP_UINTIPROTO_INDEX_IDMP_UINTIPROTO_LIMITMP_UINTIPROTO_OFFSETMP_UINTIPROTO_ITERATORMP_UINTIPROTO_KEYMP_ARRAYIPROTO_AFTER_POSITIONMP_STRIPROTO_AFTER_TUPLEMP_ARRAYIPROTO_FETCH_POSITIONMP_BOOLResponse to IPROTO_SELECTSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_OKIPROTO_SYNCMP_UINTIPROTO_SCHEMA_VERSIONMP_UINTBodyIPROTO_DATAMP_OBJECTIPROTO_POSITIONMP_STR

Example

If the ID of tspace is 512 and this is the fifth message,
conn.space.tspace:select({0},{iterator='GT',offset=1,limit=2}) will cause the following request packet:

IPROTO_SELECTexample requestSize21HeaderIPROTO_REQUEST_TYPEIPROTO_SELECTIPROTO_SYNC5BodyIPROTO_SPACE_ID512IPROTO_INDEX_ID0IPROTO_ITERATOR6IPROTO_OFFSET1IPROTO_LIMIT2IPROTO_KEY[1]

In the examples, you can find actual byte codes of an IPROTO_SELECT message.

IPROTO_INSERT

Code: 0x02.

See space_object:insert(). The body is a 2-item map:

IPROTO_INSERTSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_INSERTIPROTO_SYNCMP_UINTBodyIPROTO_SPACE_IDMP_UINTIPROTO_TUPLEMP_ARRAYResponse to IPROTO_INSERTSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_OKIPROTO_SYNCMP_UINTIPROTO_SCHEMA_VERSIONMP_UINTBodyIPROTO_DATAMP_ARRAY of tuples

For example, if the request is INSERT INTO table-name VALUES (1), (2), (3), then the response body contains an IPROTO_SQL_INFO map with SQL_INFO_ROW_COUNT = 3. SQL_INFO_ROW_COUNT can be 0 for statements that do not change rows, but can be 1 for statements that create new objects.

Example

If the ID of tspace is 512 and this is the fifth message,
conn.space.tspace:insert{1, 'AAA'} will produce the following request and response packets:

IPROTO_INSERTexample requestSize17HeaderIPROTO_REQUEST_TYPEIPROTO_INSERTIPROTO_SYNC5BodyIPROTO_SPACE_ID512IPROTO_TUPLE[1, 'AAA']IPROTO_INSERTexample responseSize36HeaderIPROTO_REQUEST_TYPEIPROTO_OKIPROTO_SYNC5IPROTO_SCHEMA_VERSION100BodyIPROTO_DATA[1, 'AAA']

The tutorial Understanding the binary protocol shows actual byte codes of the response to the IPROTO_INSERT message.

IPROTO_REPLACE

Code: 0x03.

See space_object:replace(). The body is a 2-item map, the same as for IPROTO_INSERT:

IPROTO_REPLACESizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_REPLACEIPROTO_SYNCMP_UINTBodyIPROTO_SPACE_IDMP_UINTIPROTO_TUPLEMP_ARRAY of field valuesResponse to IPROTO_REPLACESizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_OKIPROTO_SYNCMP_UINTIPROTO_SCHEMA_VERSIONMP_UINTBodyIPROTO_DATAMP_OBJECT

IPROTO_UPDATE

Code: 0x04.

See space_object:update().

The body is usually a 4-item map:

IPROTO_UPDATESizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_UPDATEIPROTO_SYNCMP_UINTBodyIPROTO_SPACE_IDMP_UINTIPROTO_INDEX_IDMP_UINTIPROTO_KEYMP_ARRAY of index keysIPROTO_TUPLEMP_ARRAY of update opsResponse to IPROTO_UPDATESizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_OKIPROTO_SYNCMP_UINTIPROTO_SCHEMA_VERSIONMP_UINTBodyIPROTO_DATAMP_OBJECT

Examples

If the operation specifies no values, then IPROTO_TUPLE is a 2-item array:

BodyIPROTO_TUPLEOperatorMP_STR: '#'Field numberMP_INT

Normally field numbers start with 1.

If the operation specifies one value, then IPROTO_TUPLE is a 3-item array:

BodyIPROTO_TUPLEOperatorMP_STR: '+', '-', '^', '|', '!', or '='Field numberMP_INTValueMP_OBJECT

Otherwise IPROTO_TUPLE is a 5-item array:

BodyIPROTO_TUPLEOperatorMP_STR: ':'Field numberMP_INTPositionMP_INTOffsetMP_INTValueMP_STR

If the ID of tspace is 512 and this is the fifth message,
conn.space.tspace:update(999, {{'=', 2, 'B'}}) will cause the following request packet:

IPROTO_UPDATEexample requestSize32HeaderIPROTO_REQUEST_TYPEIPROTO_UPDATEIPROTO_SYNC5BodyIPROTO_SPACE_ID512IPROTO_INDEX_ID0IPROTO_INDEX_BASE1IPROTO_TUPLE['=',2,'B']IPROTO_KEY[999]

The map item IPROTO_INDEX_BASE is optional.

The tutorial Understanding the binary protocol shows the actual byte codes of an IPROTO_UPDATE message.

IPROTO_UPSERT

Code: 0x09.

See space_object:upsert().

The body is usually a 4-item map:

IPROTO_UPSERTSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_UPSERTIPROTO_SYNCMP_UINTBodyIPROTO_SPACE_IDMP_UINTIPROTO_INDEX_BASEMP_UINTIPROTO_OPSMP_ARRAYIPROTO_TUPLEMP_ARRAYResponse to IPROTO_UPSERTSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_OKIPROTO_SYNCMP_UINTIPROTO_SCHEMA_VERSIONMP_UINTBodyIPROTO_DATAMP_OBJECT

IPROTO_OPS is the array of operations. It is the same as the IPROTO_TUPLE of IPROTO_UPDATE.

IPROTO_TUPLE is an array of primary-key field values.

IPROTO_DELETE

Code: 0x05.

See space_object:delete(). The body is a 3-item map:

IPROTO_DELETESizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_DELETEIPROTO_SYNCMP_UINTBodyIPROTO_SPACE_IDMP_UINTIPROTO_INDEX_IDMP_UINTIPROTO_KEYMP_ARRAY of key valuesResponse to IPROTO_DELETESizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_OKIPROTO_SYNCMP_UINTIPROTO_SCHEMA_VERSIONMP_UINTBodyIPROTO_DATAMP_OBJECT

IPROTO_EVAL

Code: 0x08.

See conn:eval(). Since the argument is a Lua expression, this is Tarantool’s way to handle non-binary with the binary protocol. Any request that does not have its own code, for example box.space.space-name:drop(), will be handled either with IPROTO_CALL or IPROTO_EVAL.

The tt administrative utility makes extensive use of eval.

The body is a 2-item map:

IPROTO_EVALSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_EVALIPROTO_SYNCMP_UINTBodyIPROTO_EXPRMP_STRIPROTO_TUPLEMP_ARRAY of argumentsResponse to IPROTO_EVALSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_OKIPROTO_SYNCMP_UINTIPROTO_SCHEMA_VERSIONMP_UINTBodyIPROTO_DATAMP_OBJECT

Примечание

For SQL-specific responses, the body is a bit different. Learn more about this type of packets.

Example

If this is the fifth message, conn:eval('return 5;') will cause:

IPROTO_EVALexample requestSize24HeaderIPROTO_REQUEST_TYPEIPROTO_EVALIPROTO_SYNCMP_UINTBodyIPROTO_EXPR'return 5;'IPROTO_TUPLE[]

IPROTO_CALL

Code: 0x0a.

See conn:call(). This is a remote stored-procedure call. Tarantool 1.6 and earlier made use of the IPROTO_CALL_16 request (code: 0x06). It is now deprecated and superseded by IPROTO_CALL.

The body is a 2-item map. The response will be a list of values, similar to the IPROTO_EVAL response. The return from conn:call is whatever the function returns.

IPROTO_CALLSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_CALLIPROTO_SYNCMP_UINTBodyIPROTO_FUNCTION_NAMEMP_STRIPROTO_TUPLEMP_ARRAY of argumentsResponse to IPROTO_CALLSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_OKIPROTO_SYNCMP_UINTIPROTO_SCHEMA_VERSIONMP_UINTBodyIPROTO_DATAMP_OBJECT

Примечание

For SQL-specific responses, the body is a bit different. Learn more about this type of packets.

IPROTO_AUTH

Code: 0x07.

For general information, see the Access control section in the administrator’s guide.

For more on how authentication is handled in the binary protocol, see the Authentication section of this document.

The client sends an authentication packet as an IPROTO_AUTH message:

IPROTO_AUTHSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_AUTHIPROTO_SYNCMP_UINTBodyIPROTO_USER_NAMEMP_STRIPROTO_TUPLEMP_ARRAYAuthentication mechanism,scramble

IPROTO_USERNAME holds the user name. IPROTO_TUPLE must be an array of 2 fields: authentication mechanism and scramble, encrypted according to the specified mechanism.

The server instance responds to an authentication packet with a standard response with 0 tuples.

To see how Tarantool handles this, look at net_box.c function netbox_encode_auth.

IPROTO_NOP

Code: 0x0c.

There is no Lua request exactly equivalent to IPROTO_NOP. It causes the LSN to be incremented. It could be sometimes used for updates where the old and new values are the same, but the LSN must be increased because a data-change must be recorded. The body is: nothing.

IPROTO_PING

Code: 0x40.

See conn:ping(). The body will be an empty map because IPROTO_PING in the header contains all the information that the server instance needs.

IPROTO_PINGSize5HeaderIPROTO_REQUEST_TYPEIPROTO_PINGIPROTO_SYNCMP_UINTBodyMP_MAP, emptyResponse to IPROTO_PINGSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_OKIPROTO_SYNCMP_UINTIPROTO_SCHEMA_VERSIONMP_UINTBodyIPROTO_DATAMP_MAP, empty

IPROTO_ID

Code: 0x49.

Clients send this message to inform the server about the protocol version and features they support. Based on this information, the server can enable or disable certain features in interacting with these clients.

The body is a 2-item map:

IPROTO_IDSizeMP_INTHeaderIPROTO_REQUEST_TYPEIPROTO_IDIPROTO_SYNCMP_UINTBodyIPROTO_VERSIONMP_UINTIPROTO_FEATURESMP_ARRAY of MP_UINT itemsIPROTO_AUTH_TYPEMP_STR

The response body has the same structure as the request body. It informs the client about the protocol version, features supported by the server, and a protocol used to generate user authentication data.

IPROTO_ID requests can be processed without authentication.

Session start and authentication

Every iproto session begins with a greeting and optional authentication.

Greeting message

When a client connects to the server instance, the instance responds with a 128-byte text greeting message, not in MsgPack format:

Tarantool <version> (<protocol>) <instance-uuid>
<salt>

For example:

Tarantool 2.10.0 (Binary) 29b74bed-fdc5-454c-a828-1d4bf42c639a
QK2HoFZGXTXBq2vFj7soCsHqTo6PGTF575ssUBAJLAI=

The greeting contains two 64-byte lines of ASCII text. Each line ends with a newline character (\n). If the line content is less than 64 bytes long, the rest of the line is filled up with symbols with an ASCII code of 0 that aren’t displayed in the console.

The first line contains the instance version and protocol type. The second line contains the session salt – a base64-encoded random string, which is usually 44 bytes long. The salt is used in the authentication packet – the IPROTO_AUTH message.

Authentication

If authentication is skipped, then the session user is 'guest' (the 'guest' user does not need a password).

If authentication is not skipped, then at any time an authentication packet can be prepared using the greeting, the user’s name and password, and sha-1 functions, as follows.

PREPARE SCRAMBLE:

    size_of_encoded_salt_in_greeting = 44;
    size_of_salt_after_base64_decode = 32;
     /* sha1() will only use the first 20 bytes */
    size_of_any_sha1_digest = 20;
    size_of_scramble = 20;

prepare 'chap-sha1' scramble:

    salt = base64_decode(encoded_salt);
    step_1 = sha1(password);
    step_2 = sha1(step_1);
    step_3 = sha1(first_20_bytes_of_salt, step_2);
    scramble = xor(step_1, step_3);
    return scramble;

Streams

Overview

The Streams and interactive transactions feature, which was added in Tarantool version v. 2.10.0, allows two things: sequential processing and interleaving.

Sequential processing: With streams there is a guarantee that the server instance will not handle the next request in a stream until it has completed the previous one.

Interleaving: For example, a series of requests can include «begin for stream #1», «begin for stream #2», «insert for stream #1», «insert for stream #2», «delete for stream #1», «commit for stream #1», «rollback for stream #2».

To work with stream transactions using iproto, the following is required:

Basic request description

Name Code Description
IPROTO_BEGIN 0x0e Begin a transaction in the specified stream
IPROTO_COMMIT 0x0f Commit the transaction in the specified stream
IPROTO_ROLLBACK 0x10 Rollback the transaction in the specified stream

IPROTO_BEGIN

Code: 0x0e.

Begin a transaction in the specified stream. See stream:begin(). The body is optional and can contain two items:

IPROTO_BEGINSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_BEGINIPROTO_SYNCMP_UINTIPROTO_STREAM_IDMP_UINTBodyIPROTO_TIMEOUTMP_DOUBLEIPROTO_TXN_ISOLATIONMP_UINT

IPROTO_TIMEOUT is an optional timeout (in seconds). After it expires, the transaction will be rolled back automatically.

IPROTO_COMMIT

Code: 0x0f.

Commit the transaction in the specified stream. See stream:commit().

IPROTO_COMMITSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_COMMITIPROTO_SYNCMP_UINTIPROTO_STREAM_IDMP_UINT

IPROTO_ROLLBACK

Codde: 0x10.

Rollback the transaction in the specified stream. See stream:rollback().

IPROTO_ROLLBACKSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_ROLLBACKIPROTO_SYNCMP_UINTIPROTO_STREAM_IDMP_UINT

Example

Suppose that the client has started a stream with the net.box module

net_box = require('net.box')
conn = net_box.connect('localhost:3302')
stream = conn:new_stream()

At this point the stream object will look like a duplicate of the conn object, with just one additional member: stream_id. Now, using stream instead of conn, the client sends two requests:

stream.space.T:insert{1}
stream.space.T:insert{2}

The header and body of these requests will be the same as in non-stream IPROTO_INSERT requests, except that the header will contain an additional item: IPROTO_STREAM_ID=0x0a with MP_UINT=0x01. It happens to equal 1 for this example because each call to conn:new_stream() assigns a new number, starting with 1.

The client makes stream transactions by sending, in order:

  1. IPROTO_BEGIN with an optional transaction timeout in the IPROTO_TIMEOUT field of the request body.
  2. The transaction data-change and query requests.
  3. IPROTO_COMMIT or IPROTO_ROLLBACK.

All these requests must contain the same IPROTO_STREAM_ID value.

A rollback will happen automatically if a disconnect occurs or the transaction timeout expires before the commit is possible.

Thus there are now multiple ways to do transactions: with net_box stream:begin() and stream:commit() or stream:rollback() which cause IPROTO_BEGIN and IPROTO_COMMIT or IPROTO_ROLLBACK with the current value of stream.stream_id; with box.begin() and box.commit() or box.rollback(); with SQL and START TRANSACTION and COMMIT or ROLLBACK. An application can use any or all of these ways.

Events and subscriptions

The commands below support asynchronous server-client notifications signalled with box.broadcast(). Servers that support the new feature set the IPROTO_FEATURE_WATCHERS feature in reply to the IPROTO_ID command. When the connection is closed, all watchers registered for it are unregistered.

The remote watcher (event subscription) protocol works in the following way:

  1. The client sends an IPROTO_WATCH packet to subscribe to the updates of a specified key defined on the server.
  2. The server sends an IPROTO_EVENT packet to the subscribed client after registration. The packet contains the key name and its current value. After that, the packet is sent every time the key value is updated with box.broadcast(), provided that the last notification was acknowledged (see below).
  3. After receiving the notification, the client sends an IPROTO_WATCH packet to acknowledge the notification.
  4. If the client doesn’t want to receive any more notifications, it unsubscribes by sending an IPROTO_UNWATCH packet.

All the three request types are asynchronous – the receiving end doesn’t send a packet in reply to any of them. Therefore, neither of them has a sync number.

IPROTO_WATCH

Code: 0x4a.

Register a new watcher for the given notification key or confirms a notification if the watcher is already subscribed. The watcher is notified after registration. After that, the notification is sent every time the key is updated. The server doesn’t reply to the request unless it fails to parse the packet.

IPROTO_WATCHSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_WATCHBodyIPROTO_EVENT_KEYMP_STR

IPROTO_UNWATCH

Code: 0x4b.

Unregister a watcher subscribed to the given notification key. The server doesn’t reply to the request unless it fails to parse the packet.

IPROTO_UNWATCHSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_UNWATCHBodyIPROTO_EVENT_KEYMP_STR

IPROTO_EVENT

Code: 0x4c.

Sent by the server to notify a client about an update of a key.

IPROTO_EVENTSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_EVENTBodyIPROTO_EVENT_KEYMP_STR(Optional)IPROTO_EVENT_DATAMP_OBJECT

IPROTO_EVENT_DATA contains data sent to a remote watcher. The parameter is optional, the default value is MP_NIL.

Graceful shutdown protocol

Overview

Since 2.10.0.

The graceful shutdown protocol is a mechanism that helps to prevent data loss in requests in case of a shutdown command. According to the protocol, when a server receives an os.exit() command or a SIGTERM signal, it does not exit immediately. Instead of that, first, the server stops listening for new connections. Then, the server sends the shutdown packets to all connections that support the graceful shutdown protocol. When a client is notified about the upcoming server exit, it stops serving any new requests and waits for active requests to complete before closing the connections. Once all connections are terminated, the server will be shut down.

The protocol uses the event subscription system. That is, the feature is available if the server supports the box.shutdown event and IPROTO_WATCH. For more information about it, see reference for the event watchers and the corresponding page in the Binary Protocol section.

How the graceful shutdown works

The shutdown protocol works in the following way:

  1. First, the server receives a shutdown request. It can be either an os.exit() command or a SIGTERM signal.
  2. Then the box.shutdown event is generated. The server broadcasts it to all subscribed remote watchers (see IPROTO_WATCH). That is, the server calls box.broadcast(„box.shutdown“, true) from the box.ctl.on_shutdown() trigger callback. Once this is done, the server stops listening for new connections.
  3. From now on, the server waits until all subscribed connections are terminated.
  4. At the same time, the client gets the box.shutdown event and shuts the connection down gracefully.
  5. After all connections are closed, the server will be stopped. Otherwise, a timeout occurs, and the Tarantool exits immediately. You can set up the required timeout with the set_on_shutdown_timeout() function.

SQL-specific requests and responses

Below are considered the IPROTO_EXECUTE and IPROTO_PREPARE requests, followed by a description of responses.

Basic request description

Name Code Description
IPROTO_EXECUTE 0x0b Execute an SQL statement (box.execute())
IPROTO_PREPARE 0x0d Prepare an SQL statement (box.prepare())

IPROTO_EXECUTE

Code: 0x0b.

The body is a 3-item map:

IPROTO_EXECUTE, prepared statementSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_EXECUTEIPROTO_SYNCMP_UINTBodyIPROTO_STMT_IDMP_INTIPROTO_SQL_BINDMP_ARRAYIPROTO_OPTIONSMP_ARRAYIPROTO_EXECUTE, SQL stringSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_EXECUTEIPROTO_SYNCMP_UINTBodyIPROTO_SQL_TEXTMP_STRIPROTO_SQL_BINDMP_ARRAYIPROTO_OPTIONSMP_ARRAY

Example 1

Suppose we prepare a statement with two ? placeholders, and execute with two parameters, thus:

n = conn:prepare([[VALUES (?, ?);]])
conn:execute(n.stmt_id, {1,'a'})

Then the body will look like this:

BodyIPROTO_STMT_ID0xd7aa741bIPROTO_SQL_BIND[1, 'a']IPROTO_OPTIONS[]

The Understanding binary protocol tutorial shows actual byte codes of the IPROTO_EXECUTE message.

To call a prepared statement with named parameters from a connector pass the parameters within an array of maps. A client should wrap each element into a map, where the key holds a name of the parameter (with a colon) and the value holds an actual value. So, to bind foo and bar to 42 and 43, a client should send IPROTO_SQL_TEXT: <...>, IPROTO_SQL_BIND: [{"foo": 42}, {"bar": 43}].

If a statement has both named and non-named parameters, wrap only named ones into a map. The rest of the parameters are positional and will be substituted in order.

Example 2

Let’s ask for full metadata and then select the two rows from a table named t1 that has columns named DD and Д:

conn.space._session_settings:update('sql_full_metadata', {{'=', 'value', true}})
conn:prepare([[SELECT dd, дд AS д FROM t1;]])

In the iproto request, there would be no IPROTO_DATA and there would be two additional items:

  • 34 00 = IPROTO_BIND_COUNT and MP_UINT = 0 (there are no parameters to bind).
  • 33 90 = IPROTO_BIND_METADATA and MP_ARRAY, size 0 (there are no parameters to bind).

Here is what the request body looks like:

BodyIPROTO_STMT_IDMP_UINTIPROTO_BIND_COUNTMP_INTIPROTO_BIND_METADATAMP_ARRAYIPROTO_METADATAIPROTO_FIELD_NAME'DD'IPROTO_FIELD_TYPE'integer'IPROTO_FIELD_IS_NULLABLEfalseIPROTO_FIELD_IS_AUTOINCREMENTtrueIPROTO_FIELD_SPANnilIPROTO_FIELD_NAME'Д'IPROTO_FIELD_TYPE'string'IPROTO_FIELD_COLL'unicode'IPROTO_FIELD_IS_NULLABLEtrueIPROTO_FIELD_SPAN'дд'

IPROTO_PREPARE

Code: 0x0d.

The body is a 1-item map:

IPROTO_PREPARESizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_PREPAREIPROTO_SYNCMP_UINTBodyIPROTO_SQL_TEXTMP_STR

The IPROTO_PREPARE map item is the same as the first item of the IPROTO_EXECUTE body for an SQL string.

Responses for SQL

After the header, for a response to an SQL statement, there will be a body that is slightly different from the body for non-SQL requests/responses.

Responses to SELECT, VALUES, or PRAGMA

If the SQL statement is SELECT or VALUES or PRAGMA, the response contains:

Response to SELECT, VALUES, or PRAGMASizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_OKIPROTO_SYNCMP_UINTIPROTO_SCHEMA_VERSIONMP_UINTBodyIPROTO_METADATAMP_ARRAY of column mapsIPROTO_DATAMP_ARRAY of tuples

Example

Let’s ask for full metadata and then select the two rows from a table named t1 that has columns named DD and Д:

conn.space._session_settings:update('sql_full_metadata', {{'=', 'value', true}})
conn:execute([[SELECT dd, дд AS д FROM t1;]])

The response body might look like this:

BodyIPROTO_METADATAIPROTO_FIELD_NAME'DD'IPROTO_FIELD_TYPE'integer'IPROTO_FIELD_IS_NULLABLEfalseIPROTO_FIELD_IS_AUTOINCREMENTtrueIPROTO_FIELD_SPANnilIPROTO_FIELD_NAME'Д'IPROTO_FIELD_TYPE'string'IPROTO_FIELD_COLL'unicode'IPROTO_FIELD_IS_NULLABLEtrueIPROTO_FIELD_SPAN'дд'IPROTO_DATAMP_ARRAY[1, 'a'], [2, 'b']

The tutorial Understanding the binary protocol shows actual byte codes of responses to the above SQL messages.

Responses to other requests

If the SQL request is not SELECT or VALUES or PRAGMA, then the response body contains only IPROTO_SQL_INFO (0x42). Usually IPROTO_SQL_INFO is a map with only one item – SQL_INFO_ROW_COUNT (0x00) – which is the number of changed rows.

Response to SQL requests other than SELECT, VALUES, or PRAGMASizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_OKIPROTO_SYNCMP_UINTIPROTO_SCHEMA_VERSIONMP_UINTBodySQL_INFOSQL_INFO_ROW_COUNTMP_UINT(Optional)SQL_INFO_AUTO_INCREMENT_IDSMP_ARRAY

For example, if the request is INSERT INTO table-name VALUES (1), (2), (3), then the response body contains an IPROTO_SQL_INFO map with SQL_INFO_ROW_COUNT = 3.

The IPROTO_SQL_INFO map may contain a second item – SQL_INFO_AUTO_INCREMENT_IDS (0x01) – which is the new primary-key value (or values) for an INSERT in a table defined with PRIMARY KEY AUTOINCREMENT. In this case the MP_MAP will have two keys, and one of the two keys will be 0x01: SQL_INFO_AUTO_INCREMENT_IDS, which is an array of unsigned integers.

Replication requests and responses

This section describes internal requests and responses that happen during replication. Each of them is distinguished by the header, containing a unique IPROTO_REQUEST_TYPE value. These values and the corresponding packet body structures are considered below.

Connectors and clients do not need to send replication packets.

General

Name Code Description
IPROTO_JOIN 0x41 Request to join a replica set
IPROTO_SUBSCRIBE 0x42 Request to subscribe to a specific node in a replica set
IPROTO_VOTE 0x44 Request for replication
IPROTO_BALLOT 0x29 Response to IPROTO_VOTE. Used during replica set bootstrap
IPROTO_FETCH_SNAPSHOT 0x45 Fetch the master’s snapshot and start anonymous replication. See replication.anon
IPROTO_REGISTER 0x46 Register an anonymous replica so it is not anonymous anymore

The master also sends heartbeat messages to the replicas. The heartbeat message’s IPROTO_REQUEST_TYPE is 0.

Below are details on individual replication requests. For synchronous replication requests, see below.

Heartbeats

Once in replication_timeout seconds, a master sends a heartbeat message to a replica, and the replica sends a response. Both messages“ IPROTO_REQUEST_TYPE is IPROTO_OK. IPROTO_TIMESTAMP is a float-64 MP_DOUBLE 8-byte timestamp.

Since version 2.11, both messages have an optional field in the body that contains the IPROTO_VCLOCK_SYNC key. The master’s heartbeat has no body if the IPROTO_VCLOCK_SYNC key is omitted.

The message from master to a replica:

Heartbeat message from masterSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_OKIPROTO_REPLICA_IDMP_UINTIPROTO_TIMESTAMPMP_DOUBLEBody(Optional)IPROTO_VCLOCK_SYNCMP_UINT

The response from the replica:

Response from replicaSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_OKIPROTO_REPLICA_IDMP_UINT(Optional)IPROTO_TIMESTAMPMP_DOUBLEBodyIPROTO_VCLOCKMP_MAP(Optional)IPROTO_VCLOCK_SYNCMP_UINTIPROTO_TERMMP_UINT

The tutorial Understanding the binary protocol shows actual byte codes of the above heartbeat examples.

IPROTO_JOIN

Code: 0x41.

To join a replica set, an instance must send an initial IPROTO_JOIN request to any node in the replica set:

IPROTO_JOINSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_JOINIPROTO_SYNCMP_UINTBodyIPROTO_INSTANCE_UUIDMP_STR - UUID of this instance

The node that receives the request does the following in response:

  1. It sends its vclock:

    Response to IPROTO_JOINSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_OKIPROTO_SYNCMP_UINTBodyIPROTO_VCLOCKMP_MAP

  2. It sends a number of INSERT requests (with additional LSN and ServerID). In this way, the data is updated on the instance that sent the IPROTO_JOIN request. The instance should not reply to these INSERT requests.

  3. It sends the new vclock’s MP_MAP in a response similar to the one above and closes the socket.

IPROTO_SUBSCRIBE

Code: 0x42.

If IPROTO_JOIN was successful, the initiator instance must send an IPROTO_SUBSCRIBE request to all the nodes listed in its box.cfg.replication:

IPROTO_SUBSCRIBESizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_SUBSCRIBEIPROTO_SYNCMP_UINTBodyIPROTO_INSTANCE_UUIDMP_STRIPROTO_CLUSTER_UUIDMP_STRIPROTO_VCLOCKMP_MAPIPROTO_SERVER_VERSIONMP_UINTIPROTO_REPLICA_ANONMP_BOOL(Optional)IPROTO_ID_FILTERMP_ARRAY

After a successful IPROTO_SUBSCRIBE request, the instance must process every request that could come from other masters. Each master’s request includes a vclock pair corresponding to that master – its instance ID and its LSN, independent from other masters.

IPROTO_ID_FILTER (0x51) is an optional key used in the SUBSCRIBE request followed by an array of ids of instances whose rows won’t be relayed to the replica. The field is encoded only when the ID list is not empty.

IPROTO_VOTE

Code: 0x44.

When connecting for replication, an instance sends an IPROTO_VOTE request. It has no body:

IPROTO_VOTESizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_VOTE

IPROTO_VOTE is critical during replica set bootstrap. The response to this request is IPROTO_BALLOT.

IPROTO_BALLOT

Code: 0x29.

This value of IPROTO_REQUEST_TYPE indicates a message sent in response to IPROTO_VOTE (not to be confused with the key IPROTO_RAFT_VOTE).

IPROTO_BALLOT and IPROTO_VOTE are critical during replica set bootstrap. IPROTO_BALLOT corresponds to a map containing the following fields:

IPROTO_BALLOT bodyIPROTO_BALLOT_IS_RO_CFGMP_BOOLIPROTO_BALLOT_VCLOCKMP_MAPIPROTO_BALLOT_GC_VCLOCKMP_MAPIPROTO_BALLOT_IS_ROMP_BOOLIPROTO_BALLOT_IS_ANONMP_BOOLIPROTO_BALLOT_IS_BOOTEDMP_BOOLIPROTO_BALLOT_CAN_LEADMP_BOOLIPROTO_BALLOT_BOOTSTRAP_LEADER_UUIDMP_STRIPROTO_BALLOT_REGISTERED_REPLICA_UUIDSMP_ARRAY

IPROTO_BALLOT_REGISTERED_REPLICA_UUIDS has the MP_ARRAY type. The array contains MP_STR elements.

Synchronous

Name Code Description
IPROTO_RAFT 0x1e Inform that the node changed its RAFT status
IPROTO_RAFT_PROMOTE 0x1f Wait, then choose new replication leader
IPROTO_RAFT_DEMOTE 0x20 Revoke the leader role from the instance
IPROTO_RAFT_CONFIRM 0x28 Confirm that the RAFT transactions have achieved quorum and can be committed
IPROTO_RAFT_ROLLBACK 0x29 Roll back the RAFT transactions because they haven’t achieved quorum

IPROTO_RAFT

Code: 0x1e.

A node broadcasts the IPROTO_RAFT request to all the replicas connected to it when the RAFT state of the node changes. It can be any actions changing the state, like starting a new election, bumping the term, voting for another node, becoming the leader, and so on.

If there should be a response, for example, in case of a vote request to other nodes, the response will also be an IPROTO_RAFT message. In this case, the node should be connected as a replica to another node from which the response is expected because the response is sent via the replication channel. In other words, there should be a full-mesh connection between the nodes.

IPROTO_RAFTSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_RAFTIPROTO_REPLICA_IDMP_UINTBodyIPROTO_RAFT_TERMMP_UINTIPROTO_RAFT_VOTEMP_UINTIPROTO_RAFT_STATEMP_UINTIPROTO_RAFT_VCLOCKMP_MAPIPROTO_RAFT_LEADER_IDMP_UINTIPROTO_RAFT_IS_LEADER_SEENMP_BOOL

IPROTO_REPLICA_ID is the ID of the replica from which the request came.

IPROTO_RAFT_PROMOTE

Code: 0x1f.

See box.ctl.promote().

IPROTO_RAFT_PROMOTESizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_RAFT_PROMOTEIPROTO_REPLICA_IDMP_UINTIPROTO_LSNMP_UINTBodyIPROTO_REPLICA_IDMP_UINTIPROTO_LSNMP_UINTIPROTO_TERMMP_UINT

In the header:

  • IPROTO_REPLICA_ID is the replica ID of the node that sent the request.
  • IPROTO_LSN is the actual LSN of the promote operation as recorded in the WAL.

In the body:

  • IPROTO_REPLICA_ID is the replica ID of the previous synchronous queue owner.
  • IPROTO_LSN is the LSN of the last operation on the previous synchronous queue owner.
  • IPROTO_TERM is the term in which the node that sent the request becomes the synchronous queue owner. This term corresponds to the value of box.info.synchro.queue.term on the instance.

IPROTO_RAFT_DEMOTE

Code: 0x20.

See box.ctl.demote().

IPROTO_RAFT_DEMOTESizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_RAFT_DEMOTEIPROTO_REPLICA_IDMP_UINTIPROTO_LSNMP_UINTBodyIPROTO_REPLICA_IDMP_UINTIPROTO_LSNMP_UINTIPROTO_TERMMP_UINT

In the header:

  • IPROTO_REPLICA_ID is the replica ID of the node that sent the request.
  • IPROTO_LSN is the actual LSN of the demote operation as recorded in the WAL.

In the body:

  • IPROTO_REPLICA_ID is the replica ID of the node that sent the request (same as the value in the header).
  • IPROTO_LSN is the LSN of the last synchronous transaction recorded in the node’s WAL.
  • IPROTO_TERM is the term in which the queue becomes empty.

IPROTO_RAFT_CONFIRM

Code: 0x28.

This message is used in replication connections between Tarantool nodes in synchronous replication. It is not supposed to be used by any client applications in their regular connections.

This message confirms that the transactions that originated from the instance with id = IPROTO_REPLICA_ID (body) have achieved quorum and can be committed, up to and including LSN = IPROTO_LSN (body).

The body is a 2-item map:

IPROTO_RAFT_CONFIRMSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_RAFT_CONFIRMIPROTO_REPLICA_IDMP_INTIPROTO_LSNMP_INTIPROTO_SYNCMP_UINTBodyIPROTO_REPLICA_IDMP_INTIPROTO_LSNMP_INT

In the header:

  • IPROTO_REPLICA_ID is the ID of the replica that sends the confirm message.
  • IPROTO_LSN is the LSN of the confirmation action.

In the body:

  • IPROTO_REPLICA_ID is the ID of the instance from which the transactions originated.
  • IPROTO_LSN is the LSN up to which the transactions should be confirmed.

Prior to Tarantool v. 2.10.0, IPROTO_RAFT_CONFIRM was called IPROTO_CONFIRM.

IPROTO_RAFT_ROLLBACK

Code: 0x29.

This message is used in replication connections between Tarantool nodes in synchronous replication. It is not supposed to be used by any client applications in their regular connections.

This message says that the transactions that originated from the instance with id = IPROTO_REPLICA_ID (body) couldn’t achieve quorum for some reason and should be rolled back, down to LSN = IPROTO_LSN (body) and including it.

The body is a 2-item map:

IPROTO_RAFT_ROLLBACKSizeMP_UINTHeaderIPROTO_REQUEST_TYPEIPROTO_RAFT_ROLLBACKIPROTO_REPLICA_IDMP_INTIPROTO_LSNMP_INTIPROTO_SYNCMP_UINTBodyIPROTO_REPLICA_IDMP_INTIPROTO_LSNMP_INT

In the header:

  • IPROTO_REPLICA_ID is the ID of the replica that sends the rollback message.
  • IPROTO_LSN is the LSN of the rollback action.

In the body:

  • IPROTO_REPLICA_ID is the ID of the instance from which the transactions originated.
  • IPROTO_LSN is the LSN starting with which all pending synchronous transactions should be rolled back.

Prior to Tarantool v. 2.10.0, IPROTO_RAFT_ROLLBACK was called IPROTO_ROLLBACK.

MessagePack extensions

Tarantool uses predefined MessagePack extension types to represent some of the special values. Extension types include MP_DECIMAL, MP_UUID, MP_ERROR, MP_DATETIME, and MP_INTERVAL. These types require special attention from the connector developers, as they must be treated separately from the default MessagePack types, and correctly mapped to programming language types.

The DECIMAL type

The MessagePack EXT type MP_EXT together with the extension type MP_DECIMAL is a header for values of the DECIMAL type.

MP_DECIMAL type is 1.

MessagePack specification defines two kinds of types:

MP_EXP + optional length imply using one of these types.

The decimal MessagePack representation looks like this:

+--------+-------------------+------------+===============+
| MP_EXT | length (optional) | MP_DECIMAL | PackedDecimal |
+--------+-------------------+------------+===============+

Here length is the length of PackedDecimal field, and it is of type MP_UINT, when encoded explicitly (i.e. when the type is ext 8/16/32).

PackedDecimal has the following structure:

 <--- length bytes -->
+-------+=============+
| scale |     BCD     |
+-------+=============+

Here scale is either MP_INT or MP_UINT.
scale = number of digits after the decimal point

BCD is a sequence of bytes representing decimal digits of the encoded number (each byte has two decimal digits each encoded using 4-bit nibbles), so byte >> 4 is the first digit and byte & 0x0f is the second digit. The leftmost digit in the array is the most significant. The rightmost digit in the array is the least significant.

The first byte of the BCD array contains the first digit of the number, represented as follows:

|  4 bits           |  4 bits           |
   = 0x                = the 1st digit

(The first nibble contains 0 if the decimal number has an even number of digits.) The last byte of the BCD array contains the last digit of the number and the final nibble, represented as follows:

|  4 bits           |  4 bits           |
   = the last digit    = nibble

The final nibble represents the number’s sign:

Examples

The decimal -12.34 will be encoded as 0xd6,0x01,0x02,0x01,0x23,0x4d:

|MP_EXT (fixext 4) | MP_DECIMAL | scale |  1   |  2,3 |  4 (minus) |
|       0xd6       |    0x01    | 0x02  | 0x01 | 0x23 | 0x4d       |

The decimal 0.000000000000000000000000000000000010 will be encoded as 0xc7,0x03,0x01,0x24,0x01,0x0c:

| MP_EXT (ext 8) | length | MP_DECIMAL | scale |  1   | 0 (plus) |
|      0xc7      |  0x03  |    0x01    | 0x24  | 0x01 | 0x0c     |

The UUID type

The MessagePack EXT type MP_EXT together with the extension type MP_UUID for values of the UUID type. Since version 2.4.1.

MP_UUID type is 2.

The MessagePack specification defines d8 to mean fixext with size 16, and a UUID’s size is always 16. So the UUID MessagePack representation looks like this:

+--------+------------+-----------------+
| MP_EXT | MP_UUID    | UuidValue       |
| = d8   | = 2        | = 16-byte value |
+--------+------------+-----------------+

The 16-byte value has 2 digits per byte. Typically, it consists of 11 fields, which are encoded as big-endian unsigned integers in the following order:

Some of the functions in Module uuid can produce values which are compatible with the UUID data type. For example, after

uuid = require('uuid')
box.schema.space.create('t')
box.space.t:create_index('i', {parts={1,'uuid'}})
box.space.t:insert{uuid.fromstr('f6423bdf-b49e-4913-b361-0740c9702e4b')}
box.space.t:select()

a peek at the server response packet will show that it contains

d8 02 f6 42 3b df b4 9e 49 13 b3 61 07 40 c9 70 2e 4b

The ERROR type

Since version 2.4.1, responses for errors have extra information following what was described in Box protocol – responses for errors. This is a «compatible» enhancement, because clients that expect old-style server responses should ignore map components that they do not recognize. Notice, however, that there has been a renaming of a constant: formerly IPROTO_ERROR in ./box/iproto_constants.h was 0x31, now IPROTO_ERROR is 0x52 and IPROTO_ERROR_24 is 0x31.

MP_ERROR type is 3.

++=========================+============================+
||                         |                            |
||   0x31: IPROTO_ERROR_24 |   0x52: IPROTO_ERROR       |
|| MP_INT: MP_STRING       | MP_MAP: extra information  |
||                         |                            |
++=========================+============================+
                        MP_MAP

The extra information, most of which is also in error object fields, is:

MP_ERROR_TYPE (0x00) (MP_STR) Type that implies source, as in error_object.base_type, for example «ClientError».

MP_ERROR_FILE (0x01) (MP_STR) Source code file where error was caught, as in error_object.trace.

MP_ERROR_LINE (0x02) (MP_UINT) Line number in source code file, as in error_object.trace.

MP_ERROR_MESSAGE (0x03) (MP_STR) Text of reason, as in error_object.message. The value here will be the same as in the IPROTO_ERROR_24 value.

MP_ERROR_ERRNO (0x04) (MP_UINT) Ordinal number of the error, as in error_object.errno. Not to be confused with MP_ERROR_ERRCODE.

MP_ERROR_ERRCODE (0x05) (MP_UINT) Number of the error as defined in errcode.h, as in error_object.code, which can also be retrieved with the C function box_error_code(). The value here will be the same as the lower part of the Response-Code-Indicator value.

MP_ERROR_FIELDS (0x06) (MP_MAPs) Additional fields depending on error type. For example, if MP_ERROR_TYPE is «AccessDeniedError», then MP_ERROR_FIELDS will include «object_type», «object_name», «access_type». This field will be omitted from the response body if there are no additional fields available.

Client and connector programmers should ensure that unknown map keys are ignored, and should check for addition of new keys in the Tarantool source code file where error object creation is defined. In version 2.4.1 the name of this source code file is mp_error.cc.

For example, in version 2.4.1 or later, if we try to create a duplicate space with
conn:eval([[box.schema.space.create('_space');]])
the server response will look like this:

ce 00 00 00 88                  MP_UINT = HEADER + BODY SIZE
83                              MP_MAP, size 3 (i.e. 3 items in header)
  00                              Response-Code-Indicator
  ce 00 00 80 0a                  MP_UINT = hexadecimal 800a
  01                              IPROTO_SYNC
  cf 00 00 00 00 00 00 00 05      MP_UINT = sync value
  05                              IPROTO_SCHEMA_VERSION
  ce 00 00 00 4e                  MP_UINT = schema version value
82                              MP_MAP, size 2
  31                              IPROTO_ERROR_24
  bd 53 70 61 63 etc.             MP_STR = "Space '_space' already exists"
  52                              IPROTO_ERROR
  81                              MP_MAP, size 1
    00                              MP_ERROR_STACK
    91                              MP_ARRAY, size 1
      86                              MP_MAP, size 6
        00                              MP_ERROR_TYPE
        ab 43 6c 69 65 6e 74 etc.       MP_STR = "ClientError"
        02                              MP_ERROR_LINE
        cd                              MP_UINT = line number
        01                              MP_ERROR_FILE
        aa 01 b6 62 75 69 6c etc.       MP_STR "builtin/box/schema.lua"
        03                              MP_ERROR_MESSAGE
        bd 53 70 61 63 65 20 etc.       MP_STR = Space.'_space'.already.exists"
        04                              MP_ERROR_ERRNO
        00                              MP_UINT = error number
        05                              MP_ERROR_ERRCODE
        0a                              MP_UINT = error code ER_SPACE_EXISTS

The DATETIME type

Since version 2.10.0. The MessagePack EXT type MP_EXT together with the extension type MP_DATETIME is a header for values of the DATETIME type. It creates a container with a payload of 8 or 16 bytes.

MP_DATETIME type is 4.

The MessagePack specification defines d7 to mean fixext with size 8 or d8 to mean fixext with size 16.

So the datetime MessagePack representation looks like this:

+---------+----------------+==========+-----------------+
| MP_EXT  | MP_DATETIME    | seconds  | nsec; tzoffset; |
| = d7/d8 | = 4            |          | tzindex;        |
+---------+----------------+==========+-----------------+

MessagePack data contains:

For more information about the datetime type, see datetime field type details and reference for the datetime module.

The INTERVAL type

Since version 2.10.0. The MessagePack EXT type MP_EXT together with the extension type MP_INTERVAL is a header for values of the INTERVAL type.

MP_INTERVAL type is 6.

The interval is saved as a variant of a map with a predefined number of known attribute names. If some attributes are undefined, they are omitted from the generated payload.

The interval MessagePack representation looks like this:

+--------+-------------------------+-------------+----------------+
| MP_EXT | Size of packed interval | MP_INTERVAL | PackedInterval |
+--------+-------------------------+-------------+----------------+

Packed interval consists of:

Each packed field has the following structure:

+----------+=====================+
| field ID |     field value     |
+----------+=====================+

The number of defined (non-null) fields can be zero. In this case, the packed interval will be encoded as integer 0.

List of the field IDs:

Example

Interval value 1 years, 200 months, -77 days is encoded in the following way:

tarantool> I = datetime.interval.new{year = 1, month = 200, day = -77}
---
...

tarantool> I
---
- +1 years, 200 months, -77 days
...

tarantool> M = msgpack.encode(I)
---
...

tarantool> M
---
- !!binary xwsGBAABAczIA9CzCAE=
...

tarantool> tohex = function(s) return (s:gsub('.', function(c) return string.format('%02X ', string.byte(c)) end)) end
---
...

tarantool> tohex(M)
---
- 'C7 0B 06 04 00 01 01 CC C8 03 D0 B3 08 01 '
...

Where:

For more information about the interval type, see interval field type details and description of the datetime module.

File formats

The WAL file format

To maintain data persistence, Tarantool writes each data change request (insert, update, delete, replace, upsert) to a write-ahead log (WAL) file in the wal.dir directory. Each data change request is assigned a continuously growing 64-bit log sequence number. The name of the WAL file is based on the log sequence number of the first record in the file, plus an extension .xlog. A new WAL file is created when the current one reaches the wal_max_size size.

Each WAL record contains:

To see the hexadecimal bytes of the given WAL file, use the hexdump command:

$ hexdump 00000000000000000000.xlog

For example, the WAL file after the first INSERT request might look the following way:

Hex dump of WAL file       Comment
--------------------       -------
58 4c 4f 47 0a             "XLOG\n"
30 2e 31 33 0a             "0.13\n" = version
53 65 72 76 65 72 3a 20    "Server: "
38 62 66 32 32 33 65 30 2d [Server UUID]\n
36 39 31 34 2d 34 62 35 35
2d 39 34 64 32 2d 64 32 62
36 64 30 39 62 30 31 39 36
0a
56 43 6c 6f 63 6b 3a 20    "Vclock: "
7b 7d                      "{}" = vclock value, initially blank
...                        (not shown = tuples for system spaces)
d5 ba 0b ab                Magic row marker always = 0xab0bbad5
19                         Length, not including length of header, = 25 bytes
00                           Record header: previous crc32
ce 8c 3e d6 70               Record header: current crc32
a7 cc 73 7f 00 00 66 39      Record header: padding
84                         msgpack code meaning "Map of 4 elements" follows
00 02                         element#1: tag=request type, value=0x02=IPROTO_INSERT
02 01                         element#2: tag=server id, value=0x01
03 04                         element#3: tag=lsn, value=0x04
04 cb 41 d4 e2 2f 62 fd d5 d4 element#4: tag=timestamp, value=an 8-byte "Float64"
82                         msgpack code meaning "map of 2 elements" follows
10 cd 02 00                   element#1: tag=space id, value=512, big byte first
21 91 01                      element#2: tag=tuple, value=1-element fixed array={1}

Tarantool processes requests atomically: a change is either accepted and recorded in the WAL, or discarded completely. To clarify how this happens, see the example with the REPLACE request below:

  1. The server instance attempts to locate the original tuple by primary key. If found, a reference to the tuple is retained for later use.
  2. The new tuple is validated. If for example it does not contain an indexed field, or it has an indexed field whose type does not match the type according to the index definition, the change is aborted.
  3. The new tuple replaces the old tuple in all existing indexes.
  4. A message is sent to the WAL writer running in a separate thread, requesting that the change be recorded in the WAL. The instance switches to work on the next request until the write is acknowledged.
  5. On success, a confirmation is sent to the client. On failure, a rollback procedure begins. During the rollback procedure, the transaction processor rolls back all changes to the database which occurred after the first failed change, from latest to oldest, up to the first failed change. All rolled back requests are aborted with ER_WAL_IO error. No new change is applied while rollback is in progress. When the rollback procedure is finished, the server restarts the processing pipeline.

One advantage of the described algorithm is that complete request pipelining is achieved, even for requests on the same value of the primary key. As a result, database performance doesn’t degrade even if all requests refer to the same key in the same space.

The transaction processor thread communicates with the WAL writer thread using asynchronous (yet reliable) messaging. The transaction processor thread, not being blocked on WAL tasks, continues to handle requests quickly even at high volumes of disk I/O. A response to a request is sent as soon as it is ready, even if there were earlier incomplete requests on the same connection. In particular, SELECT performance, even for SELECTs running on a connection packed with UPDATEs and DELETEs, remains unaffected by disk load.

The WAL writer employs a number of durability modes, as defined in configuration variable wal.mode. It is possible to turn the write-ahead log completely off, by setting the wal_mode option to none. Even without the write-ahead log it’s still possible to take a persistent copy of the entire data set with the box.snapshot() request.

An .xlog file always contains changes based on the primary key. Even if the client requested an update or delete using a secondary key, the record in the .xlog file contains the primary key.

The snapshot file format

The format of a snapshot (.snap) file is the following:

Primarily, the records in the snapshot file have the following order:

Secondarily, the .snap file’s records are ordered by primary key within space ID.

Example

The header of a .snap or .xlog file might look in the following way:

<type>\n                  SNAP\n or XLOG\n
<version>\n               currently 0.13\n
Server: <server_uuid>\n   where UUID is a 36-byte string
VClock: <vclock_map>\n    e.g. {1: 0}\n
\n

After the file header come the data tuples. Tuples begin with a row marker 0xd5ba0bab and the last tuple may be followed by an EOF marker 0xd510aded. Thus, between the file header and the EOF marker, there may be data tuples that have this form:

0            3 4                                         17
+-------------+========+============+===========+=========+
|             |        |            |           |         |
| 0xd5ba0bab  | LENGTH | CRC32 PREV | CRC32 CUR | PADDING |
|             |        |            |           |         |
+-------------+========+============+===========+=========+
   MP_FIXEXT2    MP_INT     MP_INT       MP_INT      ---

+============+ +===================================+
|            | |                                   |
|   HEADER   | |                BODY               |
|            | |                                   |
+============+ +===================================+
     MP_MAP                     MP_MAP

The recovery process

The recovery process begins when box.cfg{} happens for the first time after the Tarantool server instance starts.

The recovery process must recover the databases as of the moment when the instance was last shut down. For this it may use the latest snapshot file and any WAL files that were written after the snapshot. One complicating factor is that Tarantool has two engines – the memtx data must be reconstructed entirely from the snapshot and the WAL files, while the vinyl data will be on disk but might require updating around the time of a checkpoint. (When a snapshot happens, Tarantool tells the vinyl engine to make a checkpoint, and the snapshot operation is rolled back if anything goes wrong, so vinyl’s checkpoint is at least as fresh as the snapshot file.)

Step 1

Read the configuration parameters in the box.cfg{} request. Parameters which affect recovery may include work_dir, wal_dir, memtx_dir, vinyl_dir and force_recovery.

Step 2

Find the latest snapshot file. Use its data to reconstruct the in-memory databases. Instruct the vinyl engine to recover to the latest checkpoint.

There are actually two variations of the reconstruction procedure for memtx databases, depending on whether the recovery process is «default».

If the recovery process is default (force_recovery is false), memtx can read data in the snapshot with all indexes disabled. First, all tuples are read into memory. Then, primary keys are built in bulk, taking advantage of the fact that the data is already sorted by primary key within each space.

If the recovery process is non-default (force_recovery is true), Tarantool performs additional checking. Indexes are enabled at the start, and tuples are added one by one. This means that any unique-key constraint violations will be caught, and any duplicates will be skipped. Normally there will be no constraint violations or duplicates, so these checks are only made if an error has occurred.

Step 3

Find the WAL file that was made at the time of, or after, the snapshot file. Read its log entries until the log-entry LSN is greater than the LSN of the snapshot, or greater than the LSN of the vinyl checkpoint. This is the recovery process’s «start position»; it matches the current state of the engines.

Step 4

Redo the log entries, from the start position to the end of the WAL. The engine skips a redo instruction if it is older than the engine’s checkpoint.

Step 5

For the memtx engine, re-create all secondary indexes.

Replication internals

Server startup with replication

In addition to the recovery process described in the section Recovery process, the server must take additional steps and precautions if replication is enabled.

Once again the startup procedure is initiated by the box.cfg{} request. One of the box.cfg parameters may be replication which specifies replication source(-s). We will refer to this replica, which is starting up due to box.cfg, as the «local» replica to distinguish it from the other replicas in a replica set, which we will refer to as «distant» replicas.

If there is no snapshot .snap file and the replication parameter is empty and cfg.read_only=false:
then the local replica assumes it is an unreplicated «standalone» instance, or is the first replica of a new replica set. It will generate new UUIDs for itself and for the replica set. The replica UUID is stored in the _cluster space; the replica set UUID is stored in the _schema space. Since a snapshot contains all the data in all the spaces, that means the local replica’s snapshot will contain the replica UUID and the replica set UUID. Therefore, when the local replica restarts on later occasions, it will be able to recover these UUIDs when it reads the .snap file.

If there is no snapshot .snap file and the replication parameter is empty and cfg.read_only=true:
it cannot be the first replica of a new replica set because the first replica must be a master. Therefore an error message will occur: ER_BOOTSTRAP_READONLY. To avoid this, change the setting for this (local) instance to read_only = false, or ensure that another (distant) instance starts first and has the local instance’s UUID in its _cluster space. In the latter case, if ER_BOOTSTRAP_READONLY still occurs, set the local instance’s box.replication_connect_timeout to a larger value.

If there is no snapshot .snap file and the replication parameter is not empty and the _cluster space contains no other replica UUIDs:
then the local replica assumes it is not a standalone instance, but is not yet part of a replica set. It must now join the replica set. It will send its replica UUID to the first distant replica which is listed in replication and which will act as a master. This is called the «join request». When a distant replica receives a join request, it will send back:

If there is no snapshot .snap file and the replication parameter is not empty and the _cluster space contains other replica UUIDs:
then the local replica assumes it is not a standalone instance, and is already part of a replica set. It will send its replica UUID and replica set UUID to all the distant replicas which are listed in replication. This is called the «on-connect handshake». When a distant replica receives an on-connect handshake:

In the end, the local replica knows what replica set it belongs to, the distant replica knows that the local replica is a member of the replica set, and both replicas have the same database contents.

If there is a snapshot file and replication source is not empty:
first the local replica goes through the recovery process described in the previous section, using its own .snap and .xlog files. Then it sends a «subscribe» request to all the other replicas of the replica set. The subscribe request contains the server vector clock. The vector clock has a collection of pairs „server id, lsn“ for every replica in the _cluster system space. Each distant replica, upon receiving a subscribe request, will read its .xlog files“ requests and send them to the local replica if (lsn of .xlog file request) is greater than (lsn of the vector clock in the subscribe request). After all the other replicas of the replica set have responded to the local replica’s subscribe request, the replica startup is complete.

The following temporary limitations applied for Tarantool versions earlier than 1.7.7:

The following limitation still applies for the current Tarantool version:

Orphan status

Starting with Tarantool version 1.9, there is a change to the procedure when an instance joins a replica set. During box.cfg() the instance tries to join all nodes listed in box.cfg.replication. If the instance does not succeed with connecting to the required number of nodes (see bootstrap_strategy), it switches to the orphan status. While an instance is in orphan status, it is read-only.

To «join» a master, a replica instance must «connect» to the master node and then «sync».

«Connect» means contact the master over the physical network and receive acknowledgment. If there is no acknowledgment after box.replication_connect_timeout seconds (usually 4 seconds), and retries fail, then the connect step fails.

«Sync» means receive updates from the master in order to make a local database copy. Syncing is complete when the replica has received all the updates, or at least has received enough updates that the replica’s lag (see replication.upstream.lag in box.info()) is less than or equal to the number of seconds specified in box.cfg.replication_sync_lag. If replication_sync_lag is unset (nil) or set to TIMEOUT_INFINITY, then the replica skips the «sync» state and switches to «follow» immediately.

In order to leave orphan mode, you need to sync with a sufficient number of instances (bootstrap_strategy). To do so, you may either:

The following situations are possible.

Situation 1: bootstrap

Here box.cfg{} is being called for the first time. A replica is joining but no replica set exists yet.

  1. Set the status to „orphan“.

  2. Try to connect to all nodes from box.cfg.replication. The replica tries to connect for the replication_connect_timeout number of seconds and retries each replication_timeout seconds if needed.

  3. Abort and throw an error if a replica is not connected to the majority of nodes in box.cfg.replication.

  4. This instance might be elected as the replica set „leader“. Criteria for electing a leader include vclock value (largest is best), and whether it is read-only or read-write (read-write is best unless there is no other choice). The leader is the master that other instances must join. The leader is the master that executes box.once() functions.

  5. If this instance is elected as the replica set leader, then perform an «automatic bootstrap»:

    1. Set status to „running“.
    2. Return from box.cfg{}.

    Otherwise this instance will be a replica joining an existing replica set, so:

    1. Bootstrap from the leader. See examples in section Bootstrapping a replica set.
    2. In background, sync with all the other nodes in the replication set.

Situation 2: recovery

Here box.cfg{} is not being called for the first time. It is being called again in order to perform recovery.

  1. Perform recovery from the last local snapshot and the WAL files.
  2. Try to establish connections to all other nodes for the replication_connect_timeout number of seconds. Once replication_connect_timeout is expired or all the connections are established, proceed to the «sync» state with all the established connections.
  3. If connected, sync with all connected nodes, until the difference is not more than replication_sync_lag seconds.

Situation 3: configuration update

Here box.cfg{} is not being called for the first time. It is being called again because some replication parameter or something in the replica set has changed.

  1. Try to connect to all nodes from box.cfg.replication, within the time period specified in replication_connect_timeout.
  2. Try to sync with the connected nodes, within the time period specified in replication_sync_timeout.
  3. If earlier steps fail, change status to „orphan“. (Attempts to sync will continue in the background and when/if they succeed then „orphan“ status will end.)
  4. If earlier steps succeed, set status to „running“ (master) or „follow“ (replica).

Situation 4: rebootstrap

Here box.cfg{} is not being called. The replica connected successfully at some point in the past, and is now ready for an update from the master. But the master cannot provide an update. This can happen by accident, or more likely can happen because the replica is slow (its lag is large), and the WAL (.xlog) files containing the updates have been deleted. This is not crippling. The replica can discard what it received earlier, and then ask for the master’s latest snapshot (.snap) file contents. Since it is effectively going through the bootstrap process a second time, this is called «rebootstrapping». However, there has to be one difference from an ordinary bootstrap – the replica’s replica id will remain the same. If it changed, then the master would think that the replica is a new addition to the cluster, and would maintain a record of an instance ID of a replica that has ceased to exist. Rebootstrapping was introduced in Tarantool version 1.10.2 and is completely automatic.

Limitations

Number of parts in an index

For TREE or HASH indexes, the maximum is 255 (box.schema.INDEX_PART_MAX). For RTREE indexes, the maximum is 1 but the field is an ARRAY of up to 20 dimensions. For BITSET indexes, the maximum is 1.

Number of tuples in a hash index

4,294,967,288 (232-8).

Number of indexes in a space

128 (box.schema.INDEX_MAX).

Number of fields in a tuple

The theoretical maximum is 2,147,483,647 (box.schema.FIELD_MAX). The practical maximum is whatever is specified by the space’s field_count member, or the maximal tuple length.

Number of bytes in a tuple

The maximal number of bytes in a tuple is roughly equal to memtx.max_tuple_size or vinyl.max_tuple_size (with a metadata overhead of about 20 bytes per tuple, which is added on top of useful bytes). By default, the value of either memtx.max_tuple_size or vinyl.max_tuple_size is 1,048,576.

Number of bytes in an index key

If a field in a tuple can contain a million bytes, then the index key can contain a million bytes, so the maximum is determined by factors such as Number of bytes in a tuple, not by the index support.

Number of elements in array fields in a space with a multikey index

In a Tarantool space that has multikey indexes, any tuple cannot contain more than ~8,000 elements in a field indexed with that multikey index. This is because every element has 4 bytes of metadata, and the tuple’s metadata, which includes multikey metadata, cannot exceed 2^16 bytes.

Number of spaces

The theoretical maximum is 2,147,483,646 (box.schema.SPACE_MAX) but the practical maximum is around 65,000.

Number of connections

The practical limit is the number of file descriptors that one can set with the operating system.

Space size

The total maximum size for all spaces is in effect set by memtx.memory, which in turn is limited by the total available memory.

Update operations count

The maximum number of operations per tuple that can be in a single update is 4,000 (BOX_UPDATE_OP_CNT_MAX).

Number of users and roles

32 (BOX_USER_MAX).

Length of an index name or space name or user name

65,000 (box.schema.NAME_MAX).

Number of replicas in a replica set

32 (vclock.VCLOCK_MAX).

Примечания к версиям

This section contains information about Tarantool releases: release notes, lifecycle information, release policy, and other documents. To download Tarantool releases, check the Download page.

All currently supported versions are listed on this page below. The information about earlier versions is provided in EOL versions.

The Enterprise Edition of Tarantool is distributed in the form of an SDK that has its own versioning. See the Enterprise SDK changelog to learn about SDK version numbering and changes.

The detailed information about Tarantool version numbering and release lifecycle is available in Tarantool release policy.

Backward compatibility is guaranteed between all versions in the same release series. It is also appreciated but not guaranteed between different release series (major number changes). To learn more, read the Compatibility guarantees article.

Supported versions

Every Tarantool release series has the same lifecycle defined by the release policy. The following diagram visualizes the lifecycle of currently supported Tarantool versions:

Release calendar

The table below provides information about supported versions with links to their What’s new pages in the documentation and detailed changelogs on GitHub. For information about earlier versions, see EOL versions.

Примечание

End of life (EOL) means the release series will no longer receive any patches, updates, or feature improvements after the specified date. Versions that haven’t reached their end of life yet are shown in bold.

End of support (EOS) means that we won’t provide technical support to product versions after the specified date.

Series First release date End of life End of support Versions
3.2 August 26, 2024 August 26, 2026 Not planned yet
v. 3.2.0
3.1 April 16, 2024 April 16, 2026 Not planned yet
v. 3.1.2
v. 3.1.1
v. 3.1.0
3.0 December 26, 2023 December 26, 2025 Not planned yet
v. 3.0.2
v. 3.0.1
v. 3.0.0
2.11 LTS May 24, 2023 May 24, 2025 Not planned yet
v. 2.11.4
v. 2.11.3
v. 2.11.2
v. 2.11.1
v. 2.11.0
2.10 May 22, 2022 September 14, 2023 Not planned yet
2.10.8
2.10.7
2.10.6
2.10.5
2.10.4
2.10.3
2.10.2
2.10.1
2.10.0
2.8 August 19, 2021 April 25, 2022 December 31, 2024
2.8.4
2.8.3
2.8.2

Tarantool 3.2

Release date: August 26, 2024

Releases on GitHub: v. 3.2.0

The 3.2 release of Tarantool adds the following main product features and improvements for the Community and Enterprise editions:

Developing applications

Configuration validation

Tarantool 3.2 includes a new experimental module for validating role configurations using a declarative schema. For example, you can validate the type of configuration values, provide an array of allowed values, or specify a custom validation function.

Suppose, a sample „http-api“ custom role can accept the host and port configuration values:

roles: [ http-api ]
roles_cfg:
  http-api:
    host: '127.0.0.1'
    port: 8080

First, you need to load the experimental.config.utils.schema module:

local schema = require('experimental.config.utils.schema')

The validate_port() function can be used to check that a port value is between 1 and 65535:

local function validate_port(port, w)
    if port <= 1 or port >= 65535 then
        w.error("'port' should be between 1 and 65535, got %d", port)
    end
end

Then, you can create a schema used for validation:

  • host should be one of the specified string values.
  • port should be a number that is checked using the validate_port() function declared above.
local listen_address_schema = schema.new('listen_address', schema.record({
    host = schema.enum({ '127.0.0.1', '0.0.0.0' }),
    port = schema.scalar({
        type = 'integer',
        validate = validate_port,
    }),
}))

Finally, you can pass the specified schema to the validate() role’s function:

local function validate(cfg)
    if cfg.host and cfg.port then
        listen_address_schema:validate(cfg)
    else
        error("You need to set both host and port values")
    end
end

Protobuf encoder

The 3.2 release adds initial support for encoding structured data using Protocol buffers. First, you need to load the protobuf module:

local protobuf = require('protobuf')

To encode data, you need to define a protocol:

local customer_protocol = protobuf.protocol({
    -- Define a message and enum --
})

The two main components of the protocol are messages and enums:

  • A message specifies the structure of data, in particular, the fields and their types.
  • An enum defines a set of enumerated constants within the message.

To create a message and enum, use the message() and enum() functions, respectively:

local customer_protocol = protobuf.protocol({
    protobuf.message('Customer', {
        id = { 'int32', 1 },
        firstName = { 'string', 2 },
        lastName = { 'string', 3 },
        customerType = { 'CustomerType', 4 }
    }),
    protobuf.enum('CustomerType', {
        active = 0,
        inactive = 1,
    })
})

Once the protocol is specified, use the encode() method to encode data:

local sample_customer = customer_protocol:encode(
    'Customer',
    {
        id = 3,
        firstName = 'Andrew',
        lastName = 'Fuller',
        customerType = 1
    }
)

Next and Previous prefix iterators

This release adds two new iterators for TREE indexes: np (next prefix) and pp (previous prefix). If a key is a string value, a prefix is a common starting substring shared by multiple keys.

Suppose, the products space contains the following values:

application:instance001> box.space.products:select()
---
- - ['clothing_pants']
  - ['clothing_shirt']
  - ['electronics_laptop']
  - ['electronics_phone']
  - ['electronics_tv']
  - ['furniture_chair']
  - ['furniture_sofa']
  - ['furniture_table']
...

If you use the np iterator type and set the key value to electronics, the output should look as follows:

application:instance001> box.space.products:select({ 'electronics' }, { iterator = 'np' })
---
- - ['furniture_chair']
  - ['furniture_sofa']
  - ['furniture_table']
...

Similarly, you can use the pp iterator:

application:instance001> box.space.products:select({ 'electronics' }, { iterator = 'pp' })
---
- - ['clothing_shirt']
  - ['clothing_pants']
...

Note that new iterators work only for the memtx engine.

Tarantool configuration storage: TTL support for keys (EE)

The Enterprise Edition now includes a time-to-live (TTL) for keys in a Tarantool-based configuration storage. You can specify a TTL value in the config.storage.put() call as follows:

config.storage.put('/foo/bar', 'v1', { ttl = 60 })

Similarly, you can configure TTL in config.storage.txn():

config.storage.txn({
    predicates = { { 'revision', '==', revision } },
    on_success = { { 'put', '/foo/bar', 'v1', { ttl = 60 } } }
})

A new config.storage.info.features.ttl field allows you to check whether the current version of the configuration storage supports requests with TTL. In the example below, the conn:call() method is used to make a remote call to get the ttl field value:

local info = conn.call('config.storage.info')
if info.features == nil or not info.features.ttl then
    error('...')
end

Support for all UUID versions

Before the 3.2 version, Tarantool supported only UUIDs following the rules for RFC 4122 version 4. With v3.2, UUID values of all versions (including new 6, 7, and 8) can be parsed using the uuid module. This improves interoperability with third-party data sources whose data is processed by Tarantool.

Administration and maintenance

Interactive console

With this release, both the Tarantool and tt interactive consoles automatically add the most often used built-in modules into the environment. This means that you can start using a module without loading it with the require directive.

In the interactive session below, the config module is used to get the instance’s configuration state right after connecting to this instance:

application:instance001> config:info('v2')
---
- status: ready
  meta:
    last: &0 []
    active: *0
  alerts: []
...

To enable this new behavior, you need to set the console_session_scope_vars compat option value to new:

compat:
  console_session_scope_vars: 'new'

Observability

The 3.2 release adds the following improvements related to observability:

  • A new box.info.config field allows you to access an instance’s configuration status.
  • box.info.synchro.queue now includes the age and confirm_lag fields:
    • age – shows how much time the oldest entry in the queue has spent waiting for the quorum.
    • confirm_lag – shows how much time the latest successfully confirmed entry has waited for the quorum to gather.
  • New metrics are added:
    • tnt_memtx_tuples_data_total
    • tnt_memtx_tuples_data_read_view
    • tnt_memtx_tuples_data_garbage
    • tnt_memtx_index_total
    • tnt_memtx_index_read_view
    • tnt_vinyl_memory_tuple
    • tnt_config_alerts
    • tnt_config_status

Tarantool 3.1

Release date: April 16, 2024

Releases on GitHub: v. 3.1.2, v. 3.1.1, v. 3.1.0

The 3.1 release of Tarantool continues the development of a new cluster configuration approach introduced in the 3.0 version and adds the following main product features and improvements for the Community and Enterprise editions:

Developing applications

Error handling

This release improves the developer experience for handling errors using the box.error module. Below are listed the most notable features and changes.

Error payload fields

With the 3.1 release, you can add a custom payload to an error. The payload is passed as key-value pairs where a key is a string and a value is any Lua object. In the example below, the description key is used to keep the custom payload.

custom_error = box.error.new({ type = 'CustomInternalError',
                               message = 'Internal server error',
                               description = 'Some error details'  -- payload
})

A payload field value can be accessed using the dot syntax:

tarantool> custom_error.description
---
- Some error details
...

Error stacks

The 3.1 release simplifies creating error chains. In the earlier versions, you need to set an error cause using the set_prev(error_object) method, for example:

local ok, err = pcall(my_func)
if not ok then
    local err2 = box.error.new{type = "MyAppError", message = "my_func failed"}
    err2:set_prev(err)
    err2:raise()
end

Using this approach, you need to construct a new error without raising it, then set its cause using set_prev(), and only then raise it. Starting with the 3.1 version, you can use a new prev argument when constructing an error:

local ok, err = pcall(my_func)
if not ok then
    box.error{type = "MyAppError", message = "my_func failed", prev = err}
end

Error serialization improvements

The 3.1 release allows you to increase the verbosity of error serialization. Before the 3.1 release, a serialized error representation included only an error message:

tarantool> box.error.new({ type = 'CustomInternalError', message = 'Internal server error'})
---
- Internal server error
...

Starting with the 3.1 version, a serialized error also includes other fields that might be useful for analyzing errors:

tarantool> box.error.new({ type = 'CustomInternalError', message = 'Internal server error'})
---
- code: 0
  base_type: CustomError
  type: CustomInternalError
  custom_type: CustomInternalError
  message: Internal server error
  trace:
  - file: '[C]'
    line: 4294967295
...

Logging an error using a built-in logging module prints an error message followed by a tab space (\t) and all the payload fields serialized as a JSON map, for example:

main/104/app.lua/tarantool I> Internal server error {"code":0,"base_type":"CustomError","type":"CustomInternalError", ... }

Given that this change may change the behavior of existing code, a new box_error_serialize_verbose compat option is introduced. To try out an increased verbosity of error serialization, set this option to new:

tarantool> require('compat').box_error_serialize_verbose = 'new'
---
...

Fixed-size numeric types

The 3.1 release introduces fixed-size numeric types that might be useful to store data unencoded in an array for effective scanning. The following numeric types are added:

  • uint8: an integer in a range [0 .. 255].
  • int8: an integer in a range [-128 .. 127].
  • uint16: an integer in a range [0 .. 65,535].
  • int16: an integer in a range [-32,768 .. 32,767].
  • uint32: an integer in a range [0 .. 4,294,967,295].
  • int32: an integer in a range [-2,147,483,648 .. 2,147,483,647].
  • uint64: an integer in a range [0 .. 18,446,744,073,709,551,615].
  • int64: an integer in a range [-9,223,372,036,854,775,808 .. 9,223,372,036,854,775,807].
  • float32: a 32-bit floating point number.
  • float64: a 64-bit floating point number.

Experimental „connpool“ module

A new experimental.connpool module provides a set of features for remote connections to any cluster instance or executing remote procedure calls on an instance that meets the specified criteria. To load the experimental.connpool module, use the require() directive:

sharded_cluster:router-a-001> connpool = require('experimental.connpool')
---
...

In the 3.1 version, this module provides the following API:

  • The connect() function accepts an instance name and returns the active connection to this instance:

    sharded_cluster:router-a-001> conn = connpool.connect("storage-b-002")
---
...

    Once you have a connection, you can execute requests on a remote instance, for example, select data from a space:

    sharded_cluster:router-a-001> conn.space.bands:select({}, { limit = 5 })
---
- - [3, 804, 'Ace of Base', 1987]
  - [7, 693, 'The Doors', 1965]
  - [9, 644, 'Led Zeppelin', 1968]
  - [10, 569, 'Queen', 1970]
...

  • The filter() function returns the names of instances that match the specified conditions. In the example below, this function returns a list of instances with the storage role and specified label value:

    sharded_cluster:router-a-001> connpool.filter({ roles = { 'storage' }, labels = { dc = 'east' }})
---
- - storage-b-002
  - storage-a-002
...

  • The call() function can be used to execute a function on a remote instance. In the example below, the following conditions are specified to choose an instance to execute the vshard.storage.buckets_count function on:

    • An instance has the storage role.
    • An instance has the dc label set to west.
    • An instance is writable.
    sharded_cluster:router-a-001> connpool.call('vshard.storage.buckets_count', nil, { roles = { 'storage' }, labels = { dc = 'west' }, mode = 'rw' })
sharded_cluster:router-a-001> connpool.call('vshard.storage.buckets_count', nil, { roles = { 'storage' }, labels = { dc = 'west' }, mode = 'rw' })
---
- 500
...

Learn more in the experimental.connpool module reference.

Accessing configuration of other cluster members

In Tarantool 3.0, the config module provides the ability to work with a current instance’s configuration only. Starting with the 3.1 version, you can get all the instances that constitute a cluster and obtain the configuration of any instance of this cluster.

The config:instances() function lists all instances of the cluster:

sharded_cluster:router-a-001> require('config'):instances()
---
- storage-a-001:
    group_name: storages
    instance_name: storage-a-001
    replicaset_name: storage-a
  storage-b-002:
    group_name: storages
    instance_name: storage-b-002
    replicaset_name: storage-b
  router-a-001:
    group_name: routers
    instance_name: router-a-001
    replicaset_name: router-a
  storage-a-002:
    group_name: storages
    instance_name: storage-a-002
    replicaset_name: storage-a
  storage-b-001:
    group_name: storages
    instance_name: storage-b-001
    replicaset_name: storage-b
...

To get the specified configuration value for a certain instance, pass an instance name as an argument to config:get():

sharded_cluster:router-a-001> require('config'):get('iproto', {instance = 'storage-b-001'})
---
- readahead: 16320
  net_msg_max: 768
  listen:
  - uri: 127.0.0.1:3304
  threads: 1
  advertise:
    peer:
      login: replicator
    client: null
    sharding:
      login: storage
...

Administration and maintenance

Failover coordinator (EE)

Tarantool Enterprise Edition 3.1 introduces an external failover coordinator that monitors a Tarantool cluster and performs automatic leadership change if a current replica set leader is inaccessible.

A failover coordinator requires the replication.failover configuration option to be set to supervised:

replication:
  failover: supervised

# ...

To start a failover coordinator, execute the tarantool command with the failover option and pass a path to a YAML configuration file:

$ tarantool --failover --config /path/to/config

A failover coordinator connects to all the instances, polls them for their status, and controls that each replica set with replication.failover set to supervised has only one writable instance.

Optionally, you can configure failover timeouts and other parameters in the failover section at the global level:

failover:
  call_timeout: 1
  lease_interval: 15
  renew_interval: 5
  stateboard:
    renew_interval: 1
    keepalive_interval: 5

Sharding

The 3.1 release includes new sharding options that provide additional flexibility for configuring a sharded cluster. A new sharding.weight specifies the relative amount of data that a replica set can store. In the example below, the storage-a replica set can store twice as much data as storage-b:

# ...
replicasets:
  storage-a:
    sharding:
      weight: 2
    # ...
  storage-b:
    sharding:
      weight: 1
    # ...

The sharding.rebalancer_mode option configures whether a rebalancer is selected manually or automatically. This option can have one of three values:

  • auto (default): if there are no replica sets with the rebalancer sharding role (sharding.roles), a replica set with the rebalancer will be selected automatically among all replica sets.
  • manual: one of the replica sets should have the rebalancer sharding role. The rebalancer will be in this replica set.
  • off: rebalancing is turned off regardless of whether a replica set with the rebalancer sharding role exists or not.

Compatibility with the tt utility

With this release, the tarantoolctl utility used to administer Tarantool instances is completely removed from Tarantool packages. The latest version of the tt utility is fully compatible with Tarantool 3.1 and covers all the required functionality:

Learn how to migrate from tarantoolctl to tt in the Migration from tarantoolctl to tt section.

Tarantool 3.0

Release date: December 26, 2023

Releases on GitHub: v. 3.0.2, v. 3.0.1, v. 3.0.0

The 3.0 release of Tarantool introduces a new declarative approach for configuring a cluster, a new visual tool – Tarantool Cluster Manager, and many other new features and fixes. This document provides an overview of the most important features for the Community and Enterprise editions.

New declarative configuration

Starting with the 3.0 version, Tarantool provides the ability to configure the full topology of a cluster using a declarative YAML configuration instead of configuring each instance using a dedicated Lua script. With a new approach, you can write a local configuration in a YAML file for each instance or store configuration data in one reliable place, for example, a Tarantool or an etcd cluster.

The example below shows how a configuration of a small sharded cluster might look. In the diagram below, the cluster includes 5 instances: one router and 4 storages, which constitute two replica sets. For each replica set, the master instance is specified manually.

Cluster topology

The example below demonstrates how a topology of such a cluster might look in a YAML configuration file:

groups:
  storages:
    app:
      module: storage
    sharding:
      roles: [storage]
    replication:
      failover: manual
    replicasets:
      storage-a:
        leader: storage-a-001
        instances:
          storage-a-001:
            iproto:
              listen:
              - uri: '127.0.0.1:3302'
          storage-a-002:
            iproto:
              listen:
              - uri: '127.0.0.1:3303'
      storage-b:
        leader: storage-b-001
        instances:
          storage-b-001:
            iproto:
              listen:
              - uri: '127.0.0.1:3304'
          storage-b-002:
            iproto:
              listen:
              - uri: '127.0.0.1:3305'
  routers:
    app:
      module: router
    sharding:
      roles: [router]
    replicasets:
      router-a:
        instances:
          router-a-001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'

You can find the full sample in the GitHub documentation repository: sharded_cluster.

The latest version of the tt utility provides the ability to manage Tarantool instances configured using a new approach. You can start all instances in a cluster by executing one command, check the status of instances, or stop them:

$ tt start sharded_cluster
   • Starting an instance [sharded_cluster:storage-a-001]...
   • Starting an instance [sharded_cluster:storage-a-002]...
   • Starting an instance [sharded_cluster:storage-b-001]...
   • Starting an instance [sharded_cluster:storage-b-002]...
   • Starting an instance [sharded_cluster:router-a-001]...

Centralized configuration (EE)

Tarantool Enterprise Edition enables you to store configuration data in one reliable place, for example, an etcd cluster. To achieve this, you need to configure connection options in the config.etcd section of the configuration file, for example:

config:
  etcd:
    endpoints:
    - http://localhost:2379
    prefix: /myapp
    username: sampleuser
    password: '123456'

Using the configuration above, a Tarantool instance searches for a cluster configuration by the following path:

http://localhost:2379/myapp/config/*

Tarantool Cluster Manager (EE)

Tarantool 3.0 Enterprise Edition comes with a brand new visual tool – Tarantool Cluster Manager (TCM). It provides a web-based user interface for managing, configuring, and monitoring Tarantool EE clusters that use centralized configuration storage.

TCM stateboard

TCM can manage multiple clusters and covers a wide range of tasks, from writing a cluster’s configuration to executing commands interactively on specific instances.

TCM cluster configuration

TCM’s role-based access control system lets you manage users’ access to clusters, their configurations, and stored data.

TCM users

The built-in customizable audit logging mechanism and LDAP authentication make TCM a suitable solution for different enterprise security requirements.

TCM audit log

Administration and maintenance

Database statistics

Starting with 3.0, Tarantool provides extended statistics about memory consumption for the given space or specific tuples.

Usually, the space_object:bsize() method is used to get the size of memory occupied by the specified space:

app:instance001> box.space.books:bsize()
---
- 70348673
...

In addition to the actual data, the space requires additional memory to store supplementary information. You can see the total memory usage using box.slab.info():

app:instance001> box.slab.info().items_used
---
- 75302024
...

A new space_object:stat() <box_space-stat> method allows you to determine how the additional 5 Mb of memory is used:

app:instance001> box.space.books:stat()
---
- tuple:
    memtx:
      waste_size: 1744011
      data_size: 70348673
      header_size: 2154132
      field_map_size: 0
    malloc:
      waste_size: 0
      data_size: 0
      header_size: 0
      field_map_size: 0
...

The above report gives the following information:

  • header_size and field_map_size: the size of service information.
  • data_size: the actual size of data, which equals to space_object:bsize().
  • waste_size: the size of memory wasted due to internal fragmentation in the slab allocator.

To get such information about a specific tuple, use tuple_object:info():

app:instance001> box.space.books:get('1853260622'):info()
---
- data_size: 277
  waste_size: 9
  arena: memtx
  field_map_size: 0
  header_size: 10
...

Bootstrapping a replica set

The new version includes the capability to choose a bootstrap leader for a replica set manually. The bootstrap leader is a node that creates an initial snapshot and registers all the replicas in a replica set.

First, you need to set replication.bootstrap_strategy to config. Then, use the <replicaset_name>.bootstrap_leader option to specify a bootstrap leader.

groups:
  group001:
    replicasets:
      replicaset001:
        replication:
          bootstrap_strategy: config
        bootstrap_leader: instance001
        instances:
          instance001:
            iproto:
              listen:
              - uri: '127.0.0.1:3301'
          instance002:
            iproto:
              listen:
              - uri: '127.0.0.1:3302'
          instance003:
            iproto:
              listen:
              - uri: '127.0.0.1:3303'

Примечание

Note that in 3.0, the replication_connect_quorum option is removed. This option was used to specify the number of nodes to be up and running for starting a replica set.

Security (EE)

With the 3.0 version, Tarantool Enterprise Edition provides a set of new features that enhance security in your cluster:

  • Introduced the secure_erasing configuration option that forces Tarantool to overwrite a data file a few times before deletion to render recovery of a deleted file impossible. With the new configuration approach, you can enable this capability as follows:

    security:
  secure_erasing: true

    This option can be also set using the TT_SECURITY_SECURE_ERASING environment variable.

  • Added the auth_retries option that configures the maximum number of authentication retries before throttling is enabled. You can configure this option as follows:

    security:
  auth_retries: 3

  • Added the capability to use the new SSL certificate with the same name by reloading the configuration. To do this, use the reload() function provided by the new config module:

    app:instance001> require('config'):reload()
---
...

Audit logging (EE)

Tarantool Enterprise Edition includes the following new features for audit logging:

  • Added a unique identifier (UUID) to each audit log entry.
  • Introduced audit log severity levels. Each system audit event now has a severity level determined by its importance.
  • Added the audit_log.audit_spaces option that configures the list of spaces for which data operation events should be logged.
  • Added the audit_log.audit_extract_key option that forces the audit subsystem to log the primary key instead of a full tuple in DML operations. This might be useful for reducing audit log size in the case of large tuples.

The sample audit log configuration in the 3.0 version might look as follows, including new audit_spaces and audit_extract_key options:

audit_log:
  to: file
  file: audit_tarantool.log
  filter: [ddl,dml]
  spaces: [books]
  extract_key: true

With this configuration, an audit log entry for a DELETE operation may look like below:

{
  "time": "2023-12-19T10:09:44.664+0000",
  "uuid": "65901190-f8a6-45c1-b3a4-1a11cf5c7355",
  "severity": "VERBOSE",
  "remote": "unix/:(socket)",
  "session_type": "console",
  "module": "tarantool",
  "user": "admin",
  "type": "space_delete",
  "tag": "",
  "description": "Delete key [\"0671623249\"] from space books"
}

The entry includes the new uuid and severity fields. The last description field gives only the information about the key of the deleted tuple.

Reading flight recordings (EE)

The flight recorder available in the Enterprise Edition is an event collection tool that gathers various information about a working Tarantool instance. With the 3.0 version, you can read flight recordings using the API provided by the flightrec module.

To enable the flight recorder in a YAML file, set flightrec.enabled to true:

flightrec:
  enabled: true

Then, you can use the Lua API to open and read *.ttfr files:

app:instance001> flightrec = require('flightrec')
---
...

app:instance001> flightrec_file = flightrec.open('var/lib/instance001/20231225T085435.ttfr')
---
...

app:instance001> flightrec_file
---
- sections: &0
    requests:
      size: 10485760
    metrics:
      size: 368640
    logs:
      size: 10485760
  was_closed: false
  version: 0
  pid: 1350
...

app:instance001> for i, r in flightrec_file.sections.logs:pairs() do record = r; break end
---
...

app:instance001> record
---
- level: INFO
  fiber_name: interactive
  fiber_id: 103
  cord_name: main
  file: ./src/box/flightrec.c
  time: 2023-12-25 08:50:12.275
  message: 'Flight recorder: configuration has been done'
  line: 727
...

app:instance001> flightrec_file:close()
---
...

New DEB and RPM packages

With this release, the approach to delivering Tarantool to end users in DEB and RPM packages is slightly revised. In the previous versions, Tarantool was built for the most popular Linux distributions and their latest version.

Starting with this release, only two sets of DEB and RPM packages are delivered. The difference is that these packages include a statically compiled Tarantool binary. This approach provides the ability to install DEB and RPM packages on any Linux distributions that are based on СentOS and Debian.

To ensure that Tarantool works for a wide range of different distributions and their versions, RPM and DEB packages are prepared on CentOS 7 with glibc 2.17.

Developing applications

varbinary in Lua

In the previous versions, Tarantool already supported the varbinary type for storing data. But working with varbinary database fields required workarounds, such as using C to process such data.

The 3.0 version includes a new varbinary module for working with varbinary objects. The module implements the following functions:

  • varbinary.new() - constructs a varbinary object from a plain string.
  • varbinary.is() - returns true if the argument is a varbinary object.

In the example below, an object is created from a string:

local varbinary = require('varbinary')
local bin = varbinary.new('Hello world!')

The built-in decoders now decode binary data fields to a varbinary object by default:

local varbinary = require('varbinary')
local msgpack = require('msgpack')
varbinary.is(msgpack.decode('\xC4\x02\xFF\xFE'))
--[[
---
- true
...
]]
varbinary.is(yaml.decode('!!binary //4='))
--[[
---
- true
...
]]

This also implies that the data stored in the database under the varbinary field type is now returned to Lua not as a plain string but as a varbinary object.

It’s possible to revert to the old behavior by toggling the new binary_data_decoding compat option because this change may break backward compatibility:

compat:
  binary_data_decoding: old

Default field values

You can now assign the default values for specific fields when defining a space format. In this example, the isbn and title fields have the specified default values:

box.schema.space.create('books')
box.space.books:format({
    { name = 'id', type = 'unsigned' },
    { name = 'isbn', type = 'string', default = '9990000000000' },
    { name = 'title', type = 'string', default = 'New awesome book' },
    { name = 'year_of_publication', type = 'unsigned', default = 2023 }
})
box.space.books:create_index('primary', { parts = { 'isbn' } })

If you insert a tuple with missing fields, the default values are inserted:

app:instance001> box.space.books:insert({ 1000, nil, nil, nil })
---
- [1000, '9990000000000', 'New awesome book', 2023]
...

You can also provide a custom logic for generating a default value. To achieve this, create a function using box.schema.func.create:

box.schema.func.create('current_year', {
    language = 'Lua',
    body = "function() return require('datetime').now().year end"
})

Then, assign the function name to default_func when defining a space format:

box.space.books:format({
    -- ... --
    { name = 'year_of_publication', type = 'unsigned', default_func = 'current_year' }
})

Learn more in Default values.

Triggers

In the 3.0 version, the API for creating triggers is completely reworked. A new trigger module is introduced, allowing you to set handlers on both predefined and custom events.

To create the trigger, you need to:

  1. Provide an event name used to associate the trigger with.
  2. Define the trigger name.
  3. Provide a trigger handler function.

The code snippet below shows how to subscribe to changes in the books space:

local trigger = require('trigger')
trigger.set(
        'box.space.books.on_replace', -- event name
        'some-custom-trigger',        -- trigger name
        function(...)
            -- trigger handler
        end
)

Pagination in read views (EE)

The 2.11 release introduced the following features:

  • Read views are in-memory snapshots of the entire database that aren’t affected by future data modifications.
  • Pagination for getting data in chunks.

With the 3.0 release, a read view object supports the after and fetch_pos arguments for the select and pairs methods:

-- Select first 3 tuples and fetch a last tuple's position --
app:instance001> result, position = read_view1.space.bands:select({}, { limit = 3, fetch_pos = true })
---
...

app:instance001> result
---
- - [1, 'Roxette', 1986]
  - [2, 'Scorpions', 1965]
  - [3, 'Ace of Base', 1987]
...

app:instance001> position
---
- kQM
...

-- Then, you can pass this position as the 'after' parameter --
app:instance001> read_view1.space.bands:select({}, { limit = 3, after = position })
---
- - [4, 'The Beatles', 1960]
  - [5, 'Pink Floyd', 1965]
  - [6, 'The Rolling Stones', 1962]
...

IPROTO tuple format

Starting with the 3.0 version, the IPROTO protocol is extended to support for sending names of tuple fields in the IPROTO_CALL and other IPROTO responses. This simplifies the development of Tarantool connectors and also simplifies handling tuples received from remote procedure calls or from routers.

It’s possible to revert to the old behavior by toggling the box_tuple_extension compat option:

compat:
  box_tuple_extension: old

SQL: case-sensitive names

Starting with 3.0, names in SQL, for example, table, column, or constraint names are case-sensitive. Before the 3.0 version, the query below created a MYTABLE table:

CREATE TABLE MyTable (i INT  PRIMARY KEY);

To create the MyTable table, you needed to enclose the name into double quotes:

CREATE TABLE "MyTable" (i INT  PRIMARY KEY);

Starting with 3.0, names are case-sensitive, and double quotes are no longer needed:

CREATE TABLE MyTable (i INT  PRIMARY KEY);

For backward compatibility, the new version also supports a second lookup using an uppercase name. This means that the query below tries to find the MyTable table and then MYTABLE:

SELECT * FROM MyTable;

Stability

Handling LuaJIT compiler errors

The 3.0 release includes a fix for the gh-562 LuaJIT issue related to the inability to handle internal compiler on-trace errors using pcall. The examples of such errors are:

  • An Out of memory error might occur for select queries returning a large amount of data.
  • A Table overflow error is raised when exceeding the maximum number of keys in a table.

The script below tries to fill a Lua table with a large number of keys:

local function memory_payload()
    local t = {}
    for i = 1, 1e10 do
        t[ffi.new('uint64_t')] = i
    end
end
local res, err = pcall(memory_payload)
print(res, err)

In the previous Tarantool version with the 32-bit Lua GC, this script causes the following error despite using pcall:

PANIC: unprotected error in call to Lua API (not enough memory)

For Tarantool with the 64-bit Lua GC, this script causes a Table overflow error:

PANIC: unprotected error in call to Lua API (table overflow)

Starting with the 3.0 version, these errors are handled correctly with the following outputs:

false    not enough memory -- 32-bit Lua GC
false    table overflow    -- 64-bit Lua GC

As a result, Tarantool 3.0 becomes more stable in cases when user scripts include erroneous code.

Tarantool 2.11 (LTS)

Release date: May 24, 2023

Releases on GitHub: v. 2.11.4, v. 2.11.3, v. 2.11.2, v. 2.11.1, v. 2.11.0

The 2.11 release of Tarantool includes many new features and fixes. This document provides an overview of the most important features for the Enterprise and Community editions.

2.11 is the long-term support (LTS) release with two years of maintenance. This means that you will receive all the necessary security fixes and bug fixes throughout this period, and be able to get technical support afterward. You can learn more about the Tarantool release policy from the corresponding document.

Enterprise Edition Community Edition

Upgrading to Tarantool 2.11

Tarantool provides the live upgrade mechanism that enables cluster upgrade without downtime. In case of upgrade issues, you can roll back to the original state without downtime as well.

To learn how to upgrade to Tarantool 2.11, see Upgrades.

Enterprise Edition

Security enhancements

Encrypted SSL/TLS keys

Tarantool Enterprise Edition now supports encrypted SSL/TLS private key files protected with a password. Given that most certificate authorities generate encrypted keys, this feature simplifies the maintenance of Tarantool instances.

A password can be provided using either the new ssl_password URI parameter or in a text file specified using ssl_password_file, for example:

box.cfg{ listen = {
    uri = 'localhost:3301',
    params = {
        transport = 'ssl',
        ssl_key_file = '/path_to_key_file',
        ssl_cert_file = '/path_to_cert_file',
        ssl_ciphers = 'HIGH:!aNULL',
        ssl_password = 'topsecret'
    }
}}

To learn more, see Traffic encryption.

Security enforcement options

With 2.11, Tarantool Enterprise Edition includes new security enforcement options. These options enable you to enforce the use of strong passwords, set up a maximum password age, and so on. For example, the password_min_length configuration option specifies the minimum number of characters for a password:

box.cfg{ password_min_length = 10 }

To specify the maximum period of time (in days) a user can use the same password, you can use the password_lifetime_days option, which uses the system clock under the hood:

box.cfg{ password_lifetime_days = 365 }

Note that by default, new options are not specified. You can learn more about all the available options from the Authentication restrictions and Password policy sections.

PAP-SHA256 authentication method

By default, Tarantool uses the CHAP protocol to authenticate users and applies SHA-1 hashing to passwords. In this case, password hashes are stored in the _user space unsalted. If an attacker gains access to the database, they may crack a password, for example, using a rainbow table.

With the Enterprise Edition, you can enable PAP authentication with the SHA256 hashing algorithm. For PAP, a password is salted with a user-unique salt before saving it in the database.

Given that PAP transmits a password as plain text, Tarantool requires configuring SSL/TLS. Then, you need to specify the box.cfg.auth_type option as follows:

box.cfg{ auth_type = 'pap-sha256' }

Learn more from the Authentication protocol section.

Read views

Starting with 2.11, Tarantool Enterprise Edition provides the ability to create read views - in-memory snapshots of the entire database that aren’t affected by future data modifications. Read views can be used to make complex analytical queries. This reduces the load on the main database and improves RPS for a single Tarantool instance.

Working with read views consists of three main steps:

  1. To create a read view, call the box.read_view.open() function:

    tarantool> read_view1 = box.read_view.open({name = 'read_view1'})

  2. After creating a read view, you can access database spaces and their indexes and get data using the familiar select and pairs data-retrieval operations, for example:

    tarantool> read_view1.space.bands:select({}, {limit = 4})
---
- - [1, 'Roxette', 1986]
  - [2, 'Scorpions', 1965]
  - [3, 'Ace of Base', 1987]
  - [4, 'The Beatles', 1960]

  3. When a read view is no longer needed, close it using the read_view_object:close() method:

    tarantool> read_view1:close()

To learn more, see the Read views topic.

Data compression improvements

Tarantool Enterprise Edition now includes the zlib algorithm for tuple compression. This algorithm shows good performance in data decompression, which reduces CPU usage if the volume of read operations significantly exceeds the volume of write operations.

To use the new algorithm, set the compression option to zlib when formatting a space:

box.space.my_space:format{
    {name = 'id', type = 'unsigned'},
    {name = 'data', type = 'string', compression = 'zlib'},
}

The new compress module provides an API for compressing and decompressing arbitrary data strings using the same algorithms available for tuple compression:

compressor = require('compress.zlib').new()

data = compressor:compress('Hello world!') -- returns a binary string
compressor:decompress(data) -- returns 'Hello world!'

WAL extensions

Tarantool can use a write-ahead log not only to maintain data persistence and replication. Another use case is implementing a CDC (Change Data Capture) utility that transforms a data replication stream and provides the ability to replicate data from Tarantool to an external storage.

Write-ahead log extensions

With 2.11, Tarantool Enterprise Edition provides WAL extensions that add auxiliary information to each write-ahead log record. For example, you can enable storing old and new tuples for each write-ahead log record. This is especially useful for the update operation because a write-ahead log record contains only a key value.

See the WAL extensions topic to learn how to enable and configure WAL extensions.

Community Edition

Downgrading a database

The 2.11 version provides the ability to downgrade a database to the specified Tarantool version using the box.schema.downgrade() method. This might be useful in the case of a failed upgrade.

To prepare a database for using it on an older Tarantool instance, call box.schema.downgrade and pass the desired Tarantool version:

tarantool> box.schema.downgrade('2.8.4')

To see Tarantool versions available for downgrade, call box.schema.downgrade_versions(). The earliest release available for downgrade is 2.8.2.

New bootstrap strategy

In previous Tarantool versions, the replication_connect_quorum option was used to specify the number of running nodes to start a replica set. This option was designed to simplify a replica set bootstrap. But in fact, this behavior brought some issues during a cluster lifetime and maintenance operations, for example:

  • Users who didn’t change this option encountered problems with the partial cluster bootstrap.
  • Users who changed the option encountered problems during the instance restart.

With 2.11, replication_connect_quorum is deprecated in favor of bootstrap_strategy. This option works during a replica set bootstrap and implies sensible default values for other parameters based on the replica set configuration. Currently, bootstrap_strategy accepts two values:

  • auto: a node doesn’t boot if half or more of the other nodes in a replica set are not connected. For example, if the replication parameter contains 2 or 3 nodes, a node requires 2 connected instances. In the case of 4 or 5 nodes, at least 3 connected instances are required. Moreover, a bootstrap leader fails to boot unless every connected node has chosen it as a bootstrap leader.
  • legacy: a node requires the replication_connect_quorum number of other nodes to be connected. This option is added to keep the compatibility with the current versions of Cartridge and might be removed in the future.

Limitation of fiber execution time

Starting with 2.11, if a fiber works too long without yielding control, you can use a fiber slice to limit its execution time. The fiber_slice_default compat option controls the default value of the maximum fiber slice. In future versions, this option will be set to true by default.

There are two slice types - a warning and an error slice:

  • When a warning slice is over, a warning message is logged, for example:

    fiber has not yielded for more than 0.500 seconds

  • When an error slice is over, the fiber is cancelled and the FiberSliceIsExceeded error is thrown:

    FiberSliceIsExceeded: fiber slice is exceeded

Note that these messages can point at issues in the existing application code. These issues can cause potential problems in production.

The fiber slice is checked by all functions operating on spaces and indexes, such as index_object.select(), space_object.replace(), and so on. You can also use the fiber.check_slice() function in application code to check whether the slice for the current fiber is over.

The example below shows how to use fiber.set_max_slice() to limit the slice for all fibers. fiber.check_slice() is called inside a long-running operation to determine whether a slice for the current fiber is over.

-- app.lua --
fiber = require('fiber')
clock = require('clock')

fiber.set_max_slice({warn = 1.5, err = 3})
time = clock.monotonic()
function long_operation()
    while clock.monotonic() - time < 5 do
        fiber.check_slice()
        -- Long-running operation ⌛⌛⌛ --
    end
end
long_operation_fiber = fiber.create(long_operation)

The output should look as follows:

$ tarantool app.lua
fiber has not yielded for more than 1.500 seconds
FiberSliceIsExceeded: fiber slice is exceeded

To learn more about fiber slices, see the Limit execution time section.

Per-module logging

Tarantool 2.11 adds support for modules in the logging subsystem. You can configure different log levels for each module using the box.cfg.log_modules configuration option. The example below shows how to set the info level for module1 and the error level for module2:

tarantool> box.cfg{log_level = 'warn', log_modules = {module1 = 'info', module2 = 'error'}}
---
...

To create a log module, call the require('log').new() function:

tarantool> module1_log = require('log').new('module1')
---
...
tarantool> module2_log = require('log').new('module2')
---
...

Given that module1_log has the info logging level, calling module1_log.info shows a message but module1_log.debug is swallowed:

tarantool> module1_log.info('Hello from module1!')
2023-05-12 15:10:13.691 [39202] main/103/interactive/module1 I> Hello from module1!
---
...
tarantool> module1_log.debug('Hello from module1!')
---
...

Similarly, module2_log swallows all events with severities below the error level:

tarantool> module2_log.info('Hello from module2!')
---
...

HTTP client enhancements

Content serialization

The HTTP client now automatically serializes the content in a specific format when sending a request based on the specified Content-Type header and supports all the Tarantool built-in types. By default, the client uses the application/json content type and sends data serialized as JSON:

local http_client = require('http.client').new()
local uuid = require('uuid')
local datetime = require('datetime')

response = http_client:post('https://httpbin.org/anything', {
    user_uuid = uuid.new(),
    user_name = "John Smith",
    created_at = datetime.now()
})

The body for the request above might look like this:

{
    "user_uuid": "70ebc08d-2a9a-4ea7-baac-e9967dd45ac7",
    "user_name": "John Smith",
    "created_at": "2023-05-15T11:18:46.160910+0300"
}

To send data in a YAML or MsgPack format, set the Content-Type header explicitly to application/yaml or application/msgpack, for example:

response = http_client:post('https://httpbin.org/anything', {
    user_uuid = uuid.new(),
    user_name = "John Smith",
    created_at = datetime.now()
}, {
    headers = {
        ['Content-Type'] = 'application/yaml',
    }
})

Query and form parameters

You can now encode query and form parameters using the new params request option. In the example below, the requested URL is https://httpbin.org/get?page=1.

local http_client = require('http.client').new()

response = http_client:get('https://httpbin.org/get', {
    params = { page = 1 },
})

Similarly, you can send form parameters using the application/x-www-form-urlencoded type as follows:

local http_client = require('http.client').new()

response = http_client:post('https://httpbin.org/anything', nil, {
    params = { user_id = 1, user_name = 'John Smith' },
})

Streaming

The HTTP client now supports chunked writing and reading of request and response data, respectively. The example below shows how to get chunks of a JSON response sequentially instead of waiting for the entire response:

local http_client = require('http.client').new()
local json = require('json')

local timeout = 1
local io = http_client:get(url, nil, {chunked = true})
for i = 1, 3 do
     local data = io:read('\r\n', timeout)
     if len(data) == 0 then
         -- End of the response.
         break
     end
     local decoded = json.decode(data)
     -- <..process decoded data..>
end
io:finish(timeout)

Streaming can also be useful to upload a large file to a server or to subscribe to changes in etcd using the gRPC-JSON gateway. The example below demonstrates communication with the etcd stream interface. The request data is written line-by-line, and each line represents an etcd command.

local http_client = require('http.client').new()

local io = http_client:post('http://localhost:2379/v3/watch', nil, {chunked = true})
io:write('{"create_request":{"key":"Zm9v"}}')
local res = io:read('\n')
print(res)
-- <..you can feed more commands here..>
io:finish()

Linearizable read

Linearizability of read operations implies that if a response for a write request arrived earlier than a read request was made, this read request should return the results of the write request. Tarantool 2.11 introduces the new linearizable isolation level for box.begin():

box.begin({txn_isolation = 'linearizable', timeout = 10})
box.space.my_space:select({1})
box.commit()

When called with linearizable, box.begin() yields until the instance receives enough data from remote peers to be sure that the transaction is linearizable.

There are several prerequisites for linearizable transactions:

  • Linearizable transactions may only perform requests to synchronous, local, or temporary memtx spaces.
  • Starting a linearizable transaction requires box.cfg.memtx_use_mvcc_engine to be set to true.
  • The node is the replication source for at least N - Q + 1 remote replicas. Here N is the count of registered nodes in the cluster and Q is replication_synchro_quorum. So, for example, you can’t perform a linearizable transaction on anonymous replicas.

Explicit sequential scanning in SQL

Tarantool is primarily designed for OLTP workloads. This means that data reads are supposed to be relatively small. However, a suboptimal SQL query can cause a heavy load on a database.

The new sql_seq_scan session setting is added to explicitly cancel full table scanning. The request below should fail with the Scanning is not allowed for 'T' error:

SET SESSION "sql_seq_scan" = false;
SELECT a FROM t WHERE a + 1 > 10;

To enable table scanning explicitly, use the new SEQSCAN keyword:

SET SESSION "sql_seq_scan" = false;
SELECT a FROM SEQSCAN t WHERE a + 1 > 10;

In future versions, SEQSCAN will be required for scanning queries with the ability to disable the check using the sql_seq_scan session setting. The new behavior can be enabled using a corresponding compat option.

Strict fencing in RAFT

Leader election is implemented in Tarantool as a modification of the Raft algorithm. The 2.11 release adds the ability to specify the leader fencing mode that affects the leader election process.

Примечание

Currently, Cartridge does not support leader election using Raft.

You can control the fencing mode using the election_fencing_mode property, which accepts the following values:

  • In soft mode, a connection is considered dead if there are no responses for 4 * replication_timeout seconds both on the current leader and the followers.
  • In strict mode, a connection is considered dead if there are no responses for 2 * replication_timeout seconds on the current leader and 4 * replication_timeout seconds on the followers. This improves the chances that there is only one leader at any time.

EOL versions

This section contains information about Tarantool versions that have reached their end of life in accordance with the Tarantool release policy. This means that these versions don’t receive updates and fixes anymore. However, we still provide technical support for certain time after a version’s EOL. The current support status is reflected by the End of support column of the table below.

For information about major changes between EOL versions, see Основные изменения.

Примечание

Before 2.10.0, version numbers were subject to the legacy versioning policy.

Version Release date End of life End of support
2.10.8 September 14, 2023 September 14, 2023 Not planned yet
2.10.7 May 24, 2023 September 14, 2023 Not planned yet
2.10.6 March 22, 2023 September 14, 2023 Not planned yet
2.10.5 February 20, 2023 September 14, 2023 Not planned yet
2.10.4 November 11, 2022 September 14, 2023 Not planned yet
2.10.3 September 30, 2022 September 14, 2023 Not planned yet
2.10.2 September 1, 2022 September 14, 2023 Not planned yet
2.10.1 August 8, 2022 September 14, 2023 Not planned yet
2.10.0 May 22, 2022 September 14, 2023 Not planned yet
2.8.4 April 25, 2022 April 25, 2022 December 31, 2024
2.8.3 December 22, 2021 April 25, 2022 December 31, 2024
2.8.2 August 19, 2021 April 25, 2022 December 31, 2024
2.7.3 August 19, 2021 August 19, 2021 August 19, 2021
2.7.2 April 21, 2021 August 19, 2021 August 19, 2021
2.6.3 April 21, 2021 April 21, 2021 April 21, 2021
2.6.2 December 30, 2020 April 21, 2021 April 21, 2021
2.5.3 December 30, 2020 December 30, 2020 December 30, 2020
2.5.2 October 22, 2020 December 30, 2020 December 30, 2020
2.4.3 October 22, 2020 October 22, 2020 October 22, 2020
2.4.2 July 17, 2020 October 22, 2020 October 22, 2020
2.3.3 July 17, 2020 July 17, 2020 July 17, 2020
2.3.2 April 20, 2020 July 17, 2020 July 17, 2020
2.2.3 April 20, 2020 April 20, 2020 April 20, 2020
2.2.2 December 31, 2019 April 20, 2020 April 20, 2020
1.10.15 LTS February 20, 2023 February 20, 2023 February, 2024
1.10.14 LTS August 8, 2022 February 20, 2023 February, 2024
1.10.13 LTS April 25, 2022 February 20, 2023 February, 2024
1.10.12 LTS December 22, 2021 February 20, 2022 February 20, 2023
1.10.11 LTS August 19, 2021 February 20, 2022 February 20, 2023
1.10.10 LTS April 24, 2021 February 20, 2022 February 20, 2023
1.10.9 LTS December 30, 2020 February 20, 2022 February 20, 2023
1.10.8 LTS October 22, 2020 February 20, 2022 February 20, 2023
1.10.7 LTS July 17, 2020 February 20, 2022 February 20, 2023
1.10.6 LTS April 20, 2020 February 20, 2022 February 20, 2023
1.10.5 LTS January 14, 2020 February 20, 2022 February 20, 2023
1.10.4 LTS September 26, 2019 February 20, 2022 February 20, 2023
1.10.3 LTS April 1, 2019 February 20, 2022 February 20, 2023
1.10.2 LTS October 13, 2018 February 20, 2022 February 20, 2023

Основные изменения

Важно

This page is no longer maintained.

The table below lists major changes in Tarantool versions up to 2.11.0. For overviews of changes in newer versions, see their What’s new pages inside Примечания к версиям.

С каждым выпуском очередной версии Tarantool мы добавляем новые функции и исправления ошибок. Полные списки изменений для каждой версии можно найти в примечаниях к версиям. В этой таблице перечислены наиболее значимые изменения с номерами версий, в которых они были добавлены.

To keep track of the major features in Tarantool versions, you can use the table below.

Later versions inherit features from earlier ones in the same release series. Note that versions before 2.10.* are numbered according to the legacy release policy, while versions 2.10.0 and later adhere to the current release policy. Versions that only include bug fixes are not listed in this table.

Номер версии Характеристика
2.11.0 Tarantool Enterprise Edition
Security enhancements: Encrypted SSL/TLS keys, new security enforcement options, PAP-SHA256 support
Read views
zlib support for tuple compression
WAL extensions
Tarantool Community Edition
Pagination support (the after option)
Support for downgrading a database (box.schema.downgrade())
New bootstrap strategy
Limitation of fiber execution time
Per-module logging
HTTP client enhancements
Linearizable read
Explicit sequential scanning in SQL
Strict fencing in RAFT
2.10.5 Introduced the _vspace_sequence system space view of the _space_sequence system space (gh-7858).
The log produced during box.cfg{} now contains the build target triplet (for example, Linux-x86_64-RelWithDebInfo).
2.10.4 The JSON log format can now be used with the syslog logger (gh-7860).
SQL improvements: CASE (gh-6990) and NULLIF() (gh-6989).
Diagnostics now provide relative file paths instead of absolute ones (gh-7808).
2.10.3 RedOS 7.3 is now supported.
Added the -DENABLE_HARDENING=ON/OFF CMake option that enables hardening against memory corruption attacks (gh-7536).
2.10.2 Internal fibers cannot be cancelled from the Lua public API anymore (gh-7473)
2.10.1 Interactive transactions are now possible in remote binary consoles (gh-7413)
Improved string representation of datetime intervals (gh-7045)
2.10.0 Transaction isolation levels in Lua and IPROTO (gh-6930)
Fencing and pre-voting in RAFT (gh-6661)
Foreign keys and constraints support (gh-6436)
New DATETIME type
HTTP/2 support for the HTTP client
Preliminary support for GNU/Linux ARM64 and MacOS M1 (gh-2712, gh-6065, gh-6066, gh-6084, gh-6093, gh-6098, gh-6189)
Streams and interactive transactions in iproto (gh-5860)
Consistent SQL type system
Faster net.box module performance (improved up to 70%) (gh-6241)
Compact mode for tuples (gh-5385)
memtx_allocator option in box.cfg{} (gh-5419)
2.8.2 Symbolic log levels in the log module (gh-5882)
2.7.3, 1.10.11 LJ_DUALNUM mode support in luajit-gdb (gh-6224)
2.7.3 New table.equals method in Lua
box.info.synchro interface for synchronous replication statistics (gh-5191)
2.8.1 Multiple iproto threads (gh-5645)
Set box.cfg options with environment variables (gh-5602)
Friendly LuaJIT memory profiler report (gh-5811)
--leak-only LuaJIT memory profiler option (gh-5812)
2.7.1 LuaJIT memory profiler (gh-5442)
SQL ALTER TABLE ADD COLUMN statement support for empty tables (gh-2349, gh-3075)
2.6.3, 2.7.2 Очередь упреждающей журнализации (gh-5536)
2.6.3, 2.7.2, 2.8.1 Функция box.ctl.promote() и финализация выборов вручную (gh-3055)
2.6.1 LuaJIT platform metrics (gh-5187)
Automated leader election based on Raft algorithm (gh-1146)
Transactional manager for memtx engine (gh-4897)
2.5.3, 2.6.2, 2.7.1 Возможность задать replication_synchro_quorum в виде символьного выражения (gh-5446)
2.5.3, 2.6.2 Функция box.ctl.is_recovery_finished() для движка memtx (gh-5187)
2.5.1 Synchronous replication (beta) (gh-4842)
Allow an anonymous replica to follow another anonymous replica (gh-4696)
2.4.1 UUID type for field and index (gh-4268, gh-2916)
popen built-in module (gh-4031)
Ability to create custom error types (gh-4398)
Transparent marshalling through net.box (gh-4398)
Stacked diagnostic area (gh-1148)
2.3.1 Field name and JSON path updates (gh-1261)
Anonymous replica type (gh-3186)
DOUBLE type in SQL (gh-3812)
Support for decimals in spaces, decimal field type (gh-4333)
fiber.top() function in Lua (gh-2694)
Feed data from memory during replica initial join (gh-1271)
SQL prepared statements support and cache (gh-2592, gh-3292)
_session_settings service space (gh-4511)

Tarantool legacy release policy

Важно

This page describes the release policy that was used for Tarantool versions before 2.10.0.

For information about the current release policy, see Tarantool release policy.

Версия Tarantool состоит из трех чисел, например 2.6.2 или 1.10.9:

Таким образом, разработка каждой ПРОМЕЖУТОЧНОЙ версии проходит жизненный цикл следующим образом:

  1. Альфа-версия. Раз в квартал мы начинаем разработку новой альфа-версии, например 2.3.0, 2.4.0 и так далее. Это не совсем альфа-версия, как в типичном жизненном цикле выпуска программного обеспечения, а скорее текущая основная версия, которая находится в процессе интенсивной разработки и может быть нестабильной. Текущая альфа-версия всегда живет в основной ветви разработки.

  2. Бета-версия. Когда все запланированные функции реализованы, мы отделяем новую ветвь от основной и помечаем ее как новую бета-версию с 1 в конце для обозначения ПАТЧА, например, 2.3.1, 2.4.1 и так далее. Эту версию пока нельзя назвать стабильной (только что перестали добавлять функциональные возможности), хотя с момента последнего стабильного выпуска в ней нет известных критических регрессионных ошибок.

  3. Релизная версия (раньше называлась стабильная). Когда мы видим, что бета-версия успешно работает в течение еще одного квартала в рабочей среде или в среде разработки, пока мы исправляем обнаруженные ошибки, мы объявляем эту версию стабильной. ПАТЧ помечается цифрой 2, например, 2.3.2, 2.4.2 и так далее.

    Мы поддерживаем такую версию в течение 3 месяцев, параллельно работая над еще одной стабильной версией, в которой исправляем все найденные ошибки. Через три месяца мы выпускаем ее, обозначая ПАТЧ цифрой 3, например, 2.3.3, 2.4.3 и так далее. После установки этого тега никакие новые изменения в релизную ветвь не вносим, объявляем ее устаревшей и заменяем ее новой ПРОМЕЖУТОЧНОЙ версией.

    В релизные версии мы не добавляем никакие новые функциональные возможности, а только обратно совместимые исправления.

Как в Ubuntu, у нас есть две категории стабильных версий в плане поддержки:

Ниже представлена схема, которая иллюстрирует вышеописанную последовательность выпуска версий на примере некоторых последних версий и серий:

серия 1.10 -- 1.10.4 -- 1.10.5 -- 1.10.6 -- 1.10.7
(LTS)

....

серия 2.2 --- 2.2.1 --- 2.2.2 --- 2.2.3 (окончание поддержки)
                 |
                 V
серия 2.3  ... 2.3.0 --- 2.3.1 --- 2.3.2 --- 2.3.3 (окончание поддержки)
                           |
                           V
серия 2.4 ............. 2.4.0 --- 2.4.1 --- 2.4.2
                                     |
                                     V
серия 2.5 ....................... 2.5.0 --- 2.5.1
                                               |
                                               V
серия 2.6  ................................. 2.6.0

-----------------|---------|---------|---------|------> (время)
                   1/4 г.   1/4 г.   1/4 г.

Поддержка означает, что мы продолжаем исправлять ошибки. Мы также добавляем исправления ошибок в следующие серии версий: LTS, последнюю стабильную, бета и альфа. Если посмотреть на схему выпуска версий выше, — это означает, что исправления ошибок будут добавлены в серии 1.10, 2.4, 2.5 и 2.6.

Итак, раз в квартал выходят (см. вышеприведенную схему выпуска версий):

Когда мы находим и исправляем известную уязвимость (CVE) в любой поддерживаемой версии, мы выпускаем для этого патч, но не проставляем тег уровня ПАТЧ. Пользователи узнают о таких критических патчах из официального новостного канала Tarantool (tarantool_news).

Мы также публикуем ночные сборки и используем четвертый слот в идентификаторе версии для обозначения номера ночной сборки.

Примечание

В новой серии релизов могут быть обратно несовместимые изменения — это значит, что код на Lua, SQL или C, выполняемый в текущей серии версий, может не выполняться в следующей серии версий. Тем не менее, мы не злоупотребляем этим правилом и не вносим несовместимые изменения без причины. Обычно мы предоставляем информацию о том, насколько сформирована функциональность, в примечаниях к версии.

Обратите внимание, что структура бинарных данных всегда совместима с предыдущими сериями, а также с сериями LTS (экземпляр версии X.Y может быть запущен на основе данных X.(Y+1) или 1.10.z). Бинарный протокол также обратно совместим (как клиент-серверный протокол, так и протокол репликации).

Tarantool 2.10.8

Released on 2023-09-14.

Overview

2.10.8 is the ninth stable version of the 2.10 release series. It introduces 5 improvements and resolves 28 bugs since 2.10.7.

The “stable” label means that we have all planned features implemented and we see no high-impact issues. However, if you encounter an issue, feel free to report it on GitHub.

Compatibility

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Functionality added or changed

Box

  • The maximum length of box.cfg{} string parameters is now 512 instead of 256.

Test

Fuzz

  • LuaJIT now can be fuzzed using grammar-based fuzzer (gh-4823).

Build

  • Hardening against memory corruption attacks is now enabled by default on FreeBSD (gh-7536).
  • Added the CMake option FIBER_STACK_SIZE to set the default fiber stack size.
  • Updated libcurl to version 8.3.0.

Bugs fixed

Core

  • Fixed a bug when Tarantool failed to decode a request containing an unknown IPROTO key. The bug resulted in broken connectivity between Tarantool 2.10 and 2.11 (gh-8745).
  • Fixed a bug causing the ER_CURSOR_NO_TRANSACTION failure for transactions on synchronous spaces when the on_commit/on_rollback triggers are set (gh-8505).
  • Fixed a bug causing the effective session and user are not propagated to box.on_commit and box.on_rollback trigger callbacks when transaction is synchronous (gh-8742).
  • Fixed a crash that could happen when Tarantool is started in the background mode (gh-6128).
  • Fixed a bug when MVCC sometimes lost gap record (gh-8326).
  • Fixed a bug when MVCC rollback of prepared statement could break internal invariants (gh-8648).
  • Now MVCC engine automatically aborts a transaction if it reads changes of a prepared transaction and this transaction is aborted (gh-8654).
  • Fixed a bug that caused writing incorrect values into the stream_id field of xlog headers (gh-8783).
  • Fixed a bug when a space that is referenced by a foreign key could not be truncated even if the referring space was empty (gh-8946).
  • Fixed a crash that could happen when Tarantool is compiled by clang version 15 and above with enabled AddressSanitizer (tarantool/tarantool-qa#321).
  • Fixed a use-after-free bug in iproto server code (gh-9037).
  • Fixed a heap-buffer-overflow bug in fiber creation code (gh-9026).

Memtx

  • Fixed a heap-use-after-free bug in the transaction manager, which could occur when performing a DDL operation concurrently with a transaction on the same space (gh-8781).

Vinyl

  • Fixed a heap-use-after-free bug in the Vinyl read iterator caused by a race between a disk read and a memory dump task. The bug could lead to a crash or an invalid query result (gh-8852).

Replication

  • Fixed a possible failure to promote the desired node by box.ctl.promote() on a cluster with nodes configured with election_mode = "candidate" (gh-8497).
  • Fixed nodes configured with election_mode = 'candidate' spuriously detecting a split-vote when another candidate should win with exactly a quorum of votes for it (gh-8698).

LuaJIT

Backported patches from the vanilla LuaJIT trunk (gh-8516, gh-8825). The following issues were fixed as part of this activity:

  • Fixed canonicalization of +-0.0 keys for IR_NEWREF.
  • Fixed result truncation for bit.rol on x86_64 platforms.
  • Fixed lua_yield() invocation inside C hooks.
  • Fixed memory chunk allocation beyond the memory limit.
  • Fixed TNEW load forwarding with instable types.
  • Fixed use-def analysis for BC_VARG, BC_FUNCV.
  • Fixed BC_UCLO insertion for returns.
  • Fixed recording of BC_VARG with unused vararg values.
  • Initialization instructions on trace are now emitted only for the first member of a union.
  • Prevent integer overflow while parsing long strings.
  • Fixed various ^ operator and math.pow() function inconsistencies.
  • Fixed parsing with predicting next() and pairs().
  • Fixed binary number literal parsing. Parsing of binary number with a zero fractional part raises error too now.
  • Fixed load forwarding optimization applied after table rehashing.
  • Fixed recording of the BC_TSETM.

Lua

  • Fixed the xlog reader Lua module to show unknown row header fields. Before this change the xlog reader silently skipped them.

Netbox

  • Fixed a heap-use-after-free bug in the function creating a tuple format Lua object for net.box (gh-8889).

Box

  • Fixed the memory leaks caused by the multi-statement transaction errors in the space index building and the space format checking operations (gh-8773).
  • Fixed a bug in the box console implementation because of which the language parameter was shared between connected clients (gh-8817).
  • Fixed an invalid memory access in a corner case of a specialized comparison function (gh-8899).

Console

  • Fixed console ignoring -i flag in case stdin is not a tty (gh-5064).

Datetime

  • Fixed a bug raising a false positive error when creating new intervals with range boundary values (gh-8878).
  • Fixed a bug with buffer overflow in tnt_strptime (gh-8502).

Http

  • Fixed a streaming connection stuck if etcd is stopped unexpectedly (gh-9086).

Msgpack

  • Fixed decoding datetime intervals with fields larger than possible int32 values (gh-8887).

Tarantool 2.10.7

Released on 2023-05-24.

Overview

2.10.7 is the 8th stable version of the 2.10 release series. It resolves 17 bugs since 2.10.6.

The “stable” label means that we have all planned features implemented and we see no high-impact issues. However, if you encounter an issue, feel free to report it on GitHub.

Compatibility

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Bugs fixed

Core

  • Fixed a crash that could happen when preparing a crash report on macOS (gh-8445).
  • Fixed an integer overflow issue in net.box (ghs-121).
  • An IPROTO_EVENT packet now has the same sync number as the last corresponding IPROTO_WATCH request (gh-8393).
  • Fixed a bug because of which a dirty (not committed to WAL) DDL record could be written to a snapshot and cause a recovery failure (gh-8530).

Replication

  • Fixed a bug that occurred on applier failure: a node could start an election without having a quorum to do this (gh-8433).
  • Now if a join fails with some non-critical error, such as ER_READONLY, ER_ACCESS_DENIED, or something network-related, the instance tries to find a new master to join off and tries again (gh-6126, gh-8681).
  • States when joining a replica are renamed. Now the value of box.info.replication[id].upstream.status during join can be either wait_snapshot or fetch_snapshot instead of initial_join (gh-6126).
  • Fixed replicaset bootstrap getting stuck on some nodes with ER_READONLY when there are connectivity problems (gh-7737, gh-8681).
  • Fixed a bug when a replicaset state machine that is tracking the number of appliers according to their states could become inconsistent during reconfiguration (gh-7590).

LuaJIT

Backported patches from the vanilla LuaJIT trunk (gh-8069, gh-8516). The following issues were fixed as part of this activity:

  • Fixed emit_rma() for x64/GC64 mode for non-mov instructions.
  • Limited Lua C library path with the default PATH_MAX value of 4096 bytes.
  • Fixed assembling of IR_LREF assembling for GC64 mode on x86_64.

SQL

  • Fixed an assertion when selecting tuples with incomplete internal format (gh-8418).
  • Fixed integer overflow issues in built-in functions (ghs-119).
  • Fixed a possible assertion or segmentation fault when optimizing INSERT INTO ... SELECT FROM (gh-8661).
  • Fixed an integer overflow issue and added check for the printf() failure due to too large size (ghs-122).

Datetime

  • Fixed an error in datetime.set when timestamp is passed along with nsec, usec, or msec (gh-8583).
  • Fixed errors when the string representation of a datetime object had a negative nanosecond part (gh-8570).

Build

  • Enabled compiler optimizations for static build dependencies, which were erroneously disabled in version 2.10.3 (gh-8606).

Tarantool 2.10.6

Released on 2023-03-22.

Overview

2.10.6 is the 7th stable version of the 2.10 release series. It resolves 3 bugs since 2.10.5.

The “stable” label means that we have all planned features implemented and we see no high-impact issues. However, if you encounter an issue, feel free to report it on GitHub.

Compatibility

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Bugs fixed

Core

  • Fixed various bugs related to unsafe (i.e., coming from an unknown source) decoding and validating of MsgPack extensions (ghs-73).

LuaJIT

Backported patches from the vanilla LuaJIT trunk (gh-8069). The following issues were fixed as part of this activity:

  • Fixed successful math.min/math.max call with no args (gh-6163).
  • Fixed inconsistencies in math.min/math.max calls with a NaN arg (gh-6163).
  • Fixed pcall() call without arguments on arm64.
  • Fixed assembling of IR_{AHUV}LOAD specialized to boolean for aarch64.
  • Fixed constant rematerialization on arm64.

Box

  • Fixed a bug where box.cfg.force_recovery doesn’t work when there is no user spaces in a snapshot (gh-7974).

Tarantool 2.10.5

Released on 2023-02-20.

Overview

2.10.5 is the sixth stable version of the 2.10 release series. It introduces 5 improvements and resolves 44 bugs since 2.10.4.

The “stable” label means that we have all planned features implemented and we see no high-impact issues. However, if you encounter an issue, feel free to report it on GitHub.

Compatibility

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Functionality added or changed

Core

  • Introduced the _vspace_sequence system space view of the _space_sequence system space (gh-7858).
  • The log produced during box.cfg{} now contains the build target triplet (for example, Linux-x86_64-RelWithDebInfo).

Build

  • OpenSUSE 15.1 and 15.2 are no longer supported.
  • Updated libcurl to version 7.87.0 (gh-8150).
  • Alpine Linux 3.16 is now supported.

Bugs fixed

Core

  • Fixed a bug in fiber switching that could lead to a segmentation fault error on AArch64 systems (gh-7523, gh-7985).
  • Fixed wrong CPU architecture reported in tarantool.build.target on M1/M2 Macs (gh-7495).
  • Fixed a bug when fields could be removed from a table stored in a variable when a logging function was called on this variable (for example, log.info(a)) (gh-3853).
  • Fixed a logging bug: when logging tables with fields that have reserved internal names (such as pid) in the plain log format, such fields weren’t logged (gh-3853).
  • Added the message field when logging tables without such field in the JSON log format (gh-3853).
  • Fixed an assertion on malformed JSON message written to the log (gh-7955).
  • Fixed the bug because of which box.session.on_auth triggers were not invoked if the authenticated user didn’t exist (gh-8017).
  • Eliminated the possibility of user enumeration by analyzing errors sent in reply to malformed authentication requests (ghs-21).
  • Fixed a bug when Tarantool could execute random bytes as a Lua code after fork on systems with a glibc version earlier than 2.29 (gh-7886).
  • A referenced space or a function being used in a constraint can now be dropped in the same transaction with the referencing constraint or space (gh-7339).
  • Fixed Tarantool being stuck during a crash on macOS (gh-8023).
  • Fixed a bug that prevented collection of crash reports (gh-8083).
  • Fixed a crash in net.box that happened if the error message raised by the server contained printf formatting specifiers, such as %d or %s (gh-8043).
  • Fixed read-only statements executing successfully in transactions that were aborted by yield or timeout. Now, read-only statements fail in this case, just like write statements (gh-8123).
  • Fixed a transaction conflict reported mistakenly when a key was deleted twice with MVCC engine enabled (gh-8122).
  • net.box connections now contain information about sequences used by remote spaces (gh-7858).
  • Fixed a crash that happened if a transaction was aborted (for example, by fiber yield with MVCC off) while the space’s on_replace or before_replace trigger was running (gh-8027).
  • Fixed a possible crash when attempting to update the same field in tuple/space/index:update() more than once (gh-8216).
  • Fixed empty BITSET indexes crashing on len calls (gh-5809).
  • Fixed a crash when functional indexes were used with very specific chunk size (gh-6786).

Memtx

  • Fixed a possible repeatable read violation with reverse iterators (gh-7755).
  • Fixed a crash on series of transactions in memtx (gh-7756).
  • Fixed a phantom read that could happen after reads from different indexes followed by a rollback (gh-7828).
  • Fixed an assert in the MVCC engine (gh-7945).
  • Fixed an assertion failure in MVCC during statement preparation (gh-8104).
  • Fixed possible loss of a committed tuple after rollback of a prepared transaction (gh-7930).

Vinyl

  • Fixed a bug that could result in select() skipping an existing tuple after a rolled back delete() (gh-7947).

Replication

  • Fixed local space writes failing with error Found uncommitted sync transactions from other instance with id 1 when synchronous transaction queue belongs to another instance and isn’t empty (gh-7592).
  • Fixed an assertion failure on master when a replica resubscribes with a smaller vclock than previously seen (gh-5158).
  • A warning is now raised when replica_id is changed by a before_replace trigger while adding a new replica. Previously, there was an assertion checking this (gh-7846).
  • Fixed a segmentation fault that happened when a before_replace trigger set on space _cluster returned nil (gh-7846).
  • Fixed possible transaction conflict errors on applying a replication stream (gh-8121).

Raft

  • Fixed an assertion failure in case when an election candidate is reconfigured to a voter during an ongoning WAL write (gh-8169).
  • Fixed nodes configured with election_mode = "manual" sometimes increasing the election term excessively after their promotion (gh-8168).

LuaJIT

Backported patches from vanilla LuaJIT trunk (gh-7230). In the scope of this activity, the following issues have been resolved:

  • Fix io.close() for already closed standard output.
  • Fix trace execution and stitching inside vmevent handler (gh-6782).
  • Fixed emit_loadi() on x86/x64 emitting xor between condition check and jump instructions.
  • Fix stack top for error message when raising the OOM error (gh-3840).
  • Enabled external unwinding on several LuaJIT platforms. Now it is possible to handle ABI exceptions from Lua code (gh-6096).
  • Disabled math.modf compilation due to its rare usage and difficulties with proper implementation of the corresponding JIT machinery.
  • Fixed inconsistent behaviour on signed zeros for JIT-compiled unary minus (gh-6976).
  • Fixed IR_HREF hash calculations for non-string GC objects for GC64.
  • Fixed assembling of type-check-only variant of IR_SLOAD.
  • Enabled the platform profiler for Tarantool built with GC64 mode (gh-7919).
  • Added full-range lightuserdata support to the luajit-gdb.py extension (gh-6481).

Backported patches from vanilla LuaJIT trunk (gh-8069). In the scope of this activity, the following issues have been resolved:

  • Fixed loop realigment for dual-number mode
  • Fixed os.date() for wider libc strftime() compatibility.
  • Fix interval parsing for sysprof for dual-number mode.

Lua

  • Fixed alias detection in the YAML serializer in case the input contains objects that implement the __serialize meta method (gh-8240).

SQL

  • Fixed a bug when collation could change the type of a built-in function argument (gh-7992).
  • Fixed several bugs happening because of improper handling of malloc() failures (ghs-65, ghs-66, ghs-67, ghs-68).

Box

  • Fixed a possible error during rollback of read-only transaction statements (gh-5501).
  • Fixed a bug in space_object:create_index() when collation option is not set. Now it is inherited from the space format (gh-5104).
  • Eliminated a code injection vulnerability in the processing of the replication_synchro_quorum box.cfg() option (ghs-20, GHSA-74jr-2fq7-vp42).

Datetime

  • Fixed a segmentation fault that happened when the value passed to the %f modifier of datetime_object:format() was too big (ghs-31).

Fiber

  • Fixed the assertion fail in cord_on_yield (gh-6647).

Log

  • Fixed an incorrect facility value in syslog on Alpine and OpenBSD (gh-8269).

Build

  • Fixed -Werror build fail on Clang 15 (gh-8110).

Tarantool 2.10.4

Released on 2022-11-11.

Overview

2.10.4 is the fifth stable version of the 2.10 release series. It introduces 5 improvements and resolves 28 bugs since 2.10.3.

The “stable” label means that we have all planned features implemented and we see no high-impact issues. However, if you encounter an issue, feel free to report it on GitHub.

Compatibility

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Примечание

Now the empty string, n, nu, s, and st (that is, leading parts of num and str) are not accepted as valid field types (gh-5940). This instruction will help you upgrade to Tarantool 2.10.4 and newer if you’ve previously used these values in field types.

Functionality added or changed

Core

  • The JSON log format can now be used with the syslog logger (gh-7860).

SQL

  • New rules are applied to determine the type of CASE operation (gh-6990).
  • Now NULLIF() call results have the same type as its first argument (gh-6989).

Build

  • Diagnostics now provide relative file paths instead of absolute ones (gh-7808).
  • Now the compiler info displayed in tarantool.build.compiler and tarantool --version shows the ID and the version of the compiler that was used to build Tarantool. The output has the format ${CMAKE_C_COMPILER_ID}-${CMAKE_C_COMPILER_VERSION}, for example, Clang-14.0.0.14000029 (gh-7888).

Bugs fixed

Core

  • Fixed creation of spaces with a constraint and a foreign key on the same field (gh-7645).
  • Now the same error is returned when a password or a username provided during authorization is incorrect. This prevents user enumeration (ghs-16).
  • Added boundary checking for getenv() return values. Also, for security reasons, Tarantool code now copies these values instead of using them directly (gh-7797).
  • os.getenv() now always returns values of sane size (gh-7797).
  • Fixed the BEGIN, COMMIT, and ROLLBACK counters in the box.stat() output. Now they show the number of started, committed, and rolled back transactions (gh-7583).
  • Fixed a crash that could occur during log rotation and application exit (gh-4450).
  • Fixed a possible buffer overflow in mp_decode_decimal() and decimal_unpack() when an input string was too long (ghs-17).
  • Fixed a bug in the MsgPack library that could lead to a failure to detect invalid MsgPack input and, as a result, an out-of-bounds read (ghs-18).
  • If an error occurs during a snapshot recovery, its log now contains information about the row that caused the error (gh-7917).

Memtx

  • Fixed possible loss of committed tuples in secondary indexes with MVCC transaction manager (gh-7712).
  • Fixed an assertion being triggered on space:drop (gh-7757).
  • Fixed possible violation of the secondary index uniqueness with the transaction manager enabled (gh-7761).

LuaJIT

  • Backported patches from vanilla LuaJIT trunk (gh-7230). In the scope of this activity, the following issues have been resolved:
    • Fix overflow check in unpack() optimized by a compiler.
    • Fix recording of tonumber() with cdata argument for failed conversions (gh-7655).
    • Fix concatenation operation on cdata. It always raises an error now.
  • Fixed the Lua stack dump command (lj-stack) to support Python 2: unpacking arguments within the list initialization is not supported in it (gh-7458).

Lua

  • Fixed a crash in msgpack.decode in case the input string contains an invalid MsgPack header 0xc1 (gh-7818).

SQL

  • Fixed an assertion when INDEXED BY was used with an index that was at least third in a space (gh-5976).
  • Fixed a crash that could occur when selecting tuples with more fields than specified in the space format (gh-5310, gh-4666).
  • Fixed an assertion in JOIN when using an unsupported index (gh-5678).
  • Creating indexes on newly added fields no longer leads to assertions in SELECT queries (gh-5183).
  • Re-running a prepared statement that generates new auto-increment IDs no longer causes an error (gh-6422).
  • An error is now thrown if too many indexes were created in SQL (gh-5526).

Box

  • Revoked execute access rights to the LUA function from the public role (ghs-14).
  • Now the empty string, n, nu, s, and st (that is, leading parts of num and str) are not accepted as valid field types (gh-5940). This instruction will help you upgrade to Tarantool 2.10.4 and newer if you’ve previously used these values in field types.
  • Fixed a bug when type = box.NULL in key_def.new() resulted in type = 'unsigned' (gh-5222).
  • The _vfunc system space now has the same format as _func (gh-7822).
  • Fixed a crash on recovery from snapshots that don’t include system spaces (gh-7800).
  • Fixed a bug that occurred when a foreign key was created together with fields that participate in that foreign key (gh-7652).

Datetime

  • Fixed interval arithmetic for boundaries crossing DST (gh-7700).

    Results of datetime arithmetic operations could get a different timezone if the DST boundary has been crossed during the operation:

    tarantool> datetime.new{year=2008, month=1, day=1,
                        tz='Europe/Moscow'} +
           datetime.interval.new{month=6}
---
- 2008-07-01T01:00:00 Europe/Moscow
...

    Now we resolve tzoffset at the end of operation if tzindex is not 0.

  • Fixed subtractions for datetimes with different timezones (gh-7698).

    Previously, the timezone difference (tzoffset) was ignored in datetime subtraction operations:

    tarantool> datetime.new{tz='MSK'} - datetime.new{tz='UTC'}
---
- +0 seconds
...
tarantool> datetime.new{tz='MSK'}.timestamp -
           datetime.new{tz='UTC'}.timestamp
---
- -10800
...

    Now this difference is accumulated in the minute component of the resulting interval:

    tarantool> datetime.new{tz='MSK'} - datetime.new{tz='UTC'}
---
- -180 minutes
...

Tarantool 2.10.3

Released on 2022-09-30.

Overview

2.10.3 is the fourth stable version of the 2.10 release series. It introduces 2 improvements and resolves 19 bugs since 2.10.2.

The “stable” label means that we have all planned features implemented and we see no high-impact issues. However, if you encounter an issue, feel free to report it on GitHub.

Compatibility

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Functionality added or changed

Build

  • RedOS 7.3 is now supported.
  • Added the -DENABLE_HARDENING=ON/OFF CMake option that enables hardening against memory corruption attacks (gh-7536).

Bugs fixed

Core

  • Fixed a bug introduced in Tarantool 2.10.2: log messages could be written to data files thus causing data corruption. The issue was fixed by reverting the fix for gh-4450.
  • Switched from MT-Unsafe strerror() to MT-Safe strerror_r(). The usage of the unsafe function could result in corrupted error messages.
  • Fixed a bug when a single JSON update couldn’t insert and update a field of a map or an array in two sequential calls. It would either crash or return an error (gh-7705).

Memtx

  • Fixed incorrect handling of transaction conflicts in full scans by HASH indexes (gh-7493).
  • Fixed use after free that could occur in the transaction manager in certain states (gh-7449).
  • Fixed possible phantom reads with get on TREE indexes containing nullable parts (gh-7685).
  • Fixed an inconsistency in index:random in the context of transaction management (gh-7670).
  • Fixed unserializable reads tracked incorrectly after transaction rollbacks (gh-7343).

Replication

  • Fixed a bug when a fiber committing a synchronous transaction could hang if the instance got a term bump during that or its synchro-queue was fenced in any other way (gh-7253).
  • Fixed master occasionally deleting xlogs needed by replicas even without a restart (gh-7584).

Raft

  • Fixed a bug when box.ctl.promote() could hang and bump thousands of terms in a row if called on more than one node at the same time (part of gh-7253).
  • Fixed a bug when a node with election_mode='voter' could hang in box.ctl.promote() or become a leader (part of gh-7253).
  • Fixed a bug when a replicaset could be split into parts if a node voted for another instance while having local WAL writes unfinished (part of gh-7253).

Lua

Merger

  • Fixed use after free that could occur during iteration over merge_source:pairs() or merger:pairs() (gh-7657).

Popen

  • Fixed a race condition in <popen handle>:signal() on Mac OS 12 and newer (gh-7658).

Box

  • Fixed a bug when fiber.yield() might break the execution of a shutdown trigger (gh-7434).
  • Fixed a possible high CPU usage caused by shutdown triggers (gh-6801).

Synchro

  • Fixed assertions in debug builds and undefined behaviour in release builds when simultaneous elections started or another instance was promoted while an instance was acquiring or releasing the synchro queue (gh-7086).

Uri

  • Fixed a bug in the URI parser: tarantoolctl could not connect when the host name was skipped (gh-7479).

Tarantool 2.10.2

Released on 2022-09-01.

Overview

2.10.2 is the third stable version of the 2.10 release series. It introduces 1 improvement and resolves 8 bugs since 2.10.1.

The “stable” label means that we have all planned features implemented and we see no high-impact issues. However, if you encounter an issue, feel free to report it on GitHub.

Compatibility

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Functionality added or changed

Core

  • Certain internal fibers, such as the connection’s worker fiber, vinyl fibers, and some other fibers, cannot be cancelled from the Lua public API anymore (gh-7473).

Bugs fixed

Core

  • Fixed a crash of secondary indexes without hints (a critical regression found in 2.10.1) (gh-7605).
  • Fixed a possible crash on concurrent fiber_object:join() (gh-7489).
  • Fixed a potential nil dereference and a crash in case of an active log rotation during the program exit stage (gh-4450).
  • Fixed crashes and undefined behaviour of triggers clearing other triggers (gh-4264).

Replication

  • Fixed box.info.replication[id].downstream.lag growing indefinitely on a server when it’s not writing any new transactions (gh-7581).

Box

  • Fixed multiline commands being saved to ~/.tarantool_history as separate lines (gh-7320).
  • Fixed inheritance of field options in indexes when index parts are specified the old Tarantool 1.6 style: {<field>, <type>, ...} (gh-7614).
  • Fixed unauthorized inserts into the _truncate space (ghs-5).

Tarantool 2.10.1

Released on 2022-08-08.

Overview

Предупреждение

It is highly recommended to use Tarantool v. 2.10.2 instead.

The 2.10.1 release introduced a severe regression (gh-7605), which may pass testing with a low amount of data but impact a production server heavily. It may crash the process and, that is worse, feed incorrect data. The Tarantool development team has decided to remove all the packages associated with this release.

2.10.1 is the second stable version of the 2.10 release series. It introduces 17 improvements and resolves 52 bugs since 2.10.0.

The “stable” label means that we have all planned features implemented and we see no high-impact issues. However, if you encounter an issue, feel free to report it on GitHub.

Notable changes are:

Compatibility

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Functionality added or changed

Core

  • [Breaking change] Conflicted transactions now throw the Transaction has been aborted by conflict error on any CRUD operations until they are either rolled back (which will return no error) or committed (which will return the same error) (gh-7240).
  • Read-view transactions now become conflicted on attempts to perform DML statements immediately. Previously, this was detected only on the transaction preparation stage, that is, when calling box.commit (gh-7240).
  • Interactive transactions are now possible in remote binary consoles (gh-7413).
  • It is now possible to omit space in declarations of foreign keys that refer to the same space (gh-7200).

Datetime

  • Improved the string representation of datetime intervals. Now nanoseconds aren’t converted and attached to seconds; the intervals are displayed “as is”. Example:

    local ival = date.interval.new{year = 12345, hour = 48, min = 3, sec = 1,
                               nsec = 12345678}
print(tostring(ival))

    Before:

    '+12345 years, 48 hours, 3 minutes, 1.012345678 seconds'

    Now:

    '+12345 years, 48 hours, 3 minutes, 1 seconds, 12345678 nanoseconds'

Decimal

  • Added C module API for decimals (gh-7228).
  • Added Lua/C accessors for decimals into the module API (gh-7228).

Tuple

  • Added the box_tuple_field_by_path() function into the module API. It allow the access to tuple fields from C code using a JSON path (gh-7228).

Build

  • Fedora 30, 31, 32, and 33 are no longer supported.
  • Ubuntu 20.10 (Groovy Gorilla) and 21.04 (Hirsute Hippo) are no longer supported.
  • Updated libcurl to version 7.84.0.
  • Updated OpenSSL used for static builds to version 1.1.1q.
  • Ubuntu 21.10 (Impish Indri) is no longer supported.
  • Updated Ncurses used for static builds to version 6.3-20220716 .
  • Updated Readline used for static builds to version 8.0p1.
  • Updated libyaml to the version with fixed stack overflows.
  • Updated zstd to version 1.5.2.
  • Updated zlib used for static builds to version 1.2.12.

Bugs fixed

Core

  • Improved validation of incoming tuples. Now tuples coming over the network can’t contain malformed decimals, uuids, or datetime values (gh-6857).

  • Fixed a bug in the net.box connector because of which a client could fail to close its connection when receiving a shutdown request from the server. This could lead to the server hanging on exit (gh-7225).

  • Fixed a crash and possible undefined behaviour when using scalar and number indexes over fields containing both decimals and double Inf or NaN.

    For vinyl spaces, the above conditions could lead to wrong ordering of indexed values. To fix the issue, recreate the indexes on such spaces following this guide (gh-6377).

  • Fixed a bug because of which a net.box connection was not properly terminated when the process had a child (for example, started with popen) sharing the connection socket fd. The bug could lead to a server hanging on exit while executing the graceful shutdown protocol (gh-7256).

  • Removed an assertion on fiber_wakeup() calls with dead fibers in debug builds. Such behavior was inconsistent with release builds, in which the same calls were allowed (gh-5843).

  • Fixed the exclude_null index option not working for multikey and JSON indexes (gh-5861).

  • Fixed the performance degradation of fiber backtrace collection after the backtrace rework (gh-7207).

  • Fixed a hang when a synchronous request was issued from a net.box on_connect or on_schema_reload trigger. Now an error is raised instead (gh-5358).

  • Fixed a crash that could happen on x86 systems without the RDTSCP instruction (gh-5869).

  • Fixed a bug that allowed to access indexed fields of nested tuples with [*] in Lua (gh-5226).

  • Fixed the behavior of space_object:fselect() on binary data (gh-7040).

  • Fixed Tarantool not being able to recover from old snapshots when box.cfg.work_dir and box.cfg.memtx_dir were both set (gh-7232).

  • Fixed Tarantool terminations on error messages with invalid UTF-8 sequences (gh-6781 and gh-6934).

  • Fixed a bug when the Transaction is active at return from function error was overwriting expression evaluation errors in case the expression begins a transaction (gh-7288).

  • Added type checking for options in net.box’s remote queries and connect method. Now graceful errors are thrown in case of incorrect options (gh-6063, gh-6530).

  • Fixed space_object:format() and space_object.foreign_key returning incorrect numbers of foreign key fields (gh-7350).

  • Fixed the foreign key check on space_object:truncate() calls (gh-7309).

  • Fixed a crash when box.stat.net.thread[i] is called with invalid i values (gh-7196).

  • Fixed a low-probability stack overflow bug in the qsort implementation.

Memtx

  • Fixed the ability to perform read-only operations in conflicting transactions in memtx, which led to spurious results (gh-7238).
  • Fixed false assertion on repeatable replace with the memtx transaction manager enabled (gh-7214).
  • Fixed false transaction conflict on repeatable insert/upsert with the memtx transaction manager enabled (gh-7217).
  • Fixed dirty reads in the GT iterator of HASH indexes (gh-7477).
  • Fixed phantom reads in reverse iterators (gh-7409).
  • Fixed select with LE iterator in memtx TREE index returning deleted tuple (gh-7432).
  • Fixed incorrect handling of corner cases gap tracking in transaction manager (gh-7375).
  • Fixed a bug in the memtx hash index implementation that could lead to uncommitted data written to a snapshot file (gh-7539).

Vinyl

  • Fixed a bug in the vinyl upsert squashing optimization that could lead to a segmentation fault error (gh-5080).
  • Fixed a bug in the vinyl garbage collector. It could skip stale tuples stored in a secondary index if upsert operations were used on the space before the index was created (gh-3638).
  • Fixed a bug in the vinyl read iterator that could result in a significant performance degradation of range select requests in the presence of an intensive write workload (gh-5700).
  • Explicitly disabled the hot standby mode for vinyl. Now an attempt to enable the hot standby mode in case the master instance has vinyl spaces results in an error. Before this change, the behavior was undefined (gh-6565).

Replication

  • Added the logging of the error reason on a replica in case when the master didn’t send a greeting message (gh-7204).
  • Fixed replication being stuck occasionally for no obvious reasons.
  • Fixed a possible split-brain when the old synchro queue owner might finalize the transactions in the presence of the new owner (gh-5295).
  • Improved the detection of possible split-brain situations, for example, when multiple leaders were working independently due to manually lowered quorum. Once a node discovers that it received some foreign data, it immediately stops replication from such a node with an ER_SPLIT_BRAIN error (gh-5295).
  • Fixed a false positive split-brain error after box.ctl.demote() (gh-7286).
  • Fixed a bug when followers with box.cfg.election_mode turned on did not notice the leader hang due to a long request, such as a select{} from a large space or a pairs iteration without yields between loop cycles (gh-7512).

LuaJIT

Backported patches from vanilla LuaJIT trunk (gh-6548 and gh-7230). In the scope of this activity, the following issues have been resolved:

  • Fixed emitting for fuse load of constant in GC64 mode (gh-4095, gh-4199, gh-4614).
  • Now initialization of zero-filled struct is compiled (gh-4630, gh-5885).
  • Actually implemented maxirconst option for tuning JIT compiler.
  • Fixed JIT stack of Lua slots overflow during recording for metamethod calls.
  • Fixed bytecode dump unpatching for JLOOP in up-recursion compiled functions.
  • Fixed FOLD rule for strength reduction of widening in cdata indexing.
  • Fixed string.char() recording without arguments.
  • Fixed print() behaviour with the reloaded default metatable for numbers.
  • tonumber("-0") now saves the sign of number for conversion.
  • tonumber() now gives predictable results for negative non-base-10 numbers.
  • Fixed write barrier for debug.setupvalue() and lua_setupvalue().
  • Fixed conflict between 64 bit lightuserdata and ITERN key for ARM64.
  • Fixed emitting assembly for HREFK on ARM64.
  • Fixed pass-by-value struct in FFI calls on ARM64.
  • jit.p now flushes and closes output file after run, not at program exit.
  • Fixed jit.p profiler interaction with GC finalizers.
  • Fixed the case for partial recording of vararg function body with the fixed number of result values in with LJ_GC64 (i.e. LJ_FR2 enabled) (gh-7172).
  • Added /proc/self/exe symlink resolution to the symtab module to obtain the .symtab section for the Tarantool executable.
  • Introduced stack sandwich support to sysprof’s parser (gh-7244).
  • Disabled proto and trace information dumpers in sysprof’s default mode. Attempts to use them lead to a segmentation fault due to an uninitialized buffer (gh-7264).
  • Fixed handling of errors during trace snapshot restore.

Lua

  • The fiber_obj:info() now correctly handles its options (gh-7210).
  • Fixed a bug when Ctrl+C doesn’t discard the multiline input (gh-7109).

SQL

  • Fixed the creation of ephemeral space format in ORDER BY (gh-7043).
  • The result type of arithmetic operations between two unsigned values is now INTEGER (gh-7295).
  • Fixed a bug with the ANY type in the ephemeral space format in ORDER BY (gh-7043).
  • Truncation of a space no longer corrupts prepared statements (gh-7358).

Datetime

  • Fixed a bug when date:set{hour=nil,min=XXX} did not retain the original hour value (gh-7298).
  • Introduced the validation of incoming data at the moment messagepack is converted to datetime (gh-6723).

HTTP client

  • Enabled the automatic detection of system CA certificates in the runtime (gh-7372). It was disabled in 2.10.0, which led to the inability to use HTTPS without the verify_peer = false option.

Build

  • Fixed a build failure with gcc if libpbf is installed (gh-7292).
  • Fixed the static build on Mac OS 11 and newer (gh-7459).

Tarantool 2.10.0

Released on 2022-05-22.

Overview

2.10.0 is the first stable version of the 2.10 release series. It introduces 107 improvements and resolves 131 bugs since version 2.8.1.

The “stable” label means that we have all planned features implemented and we see no high-impact issues. However, if you encounter an issue, feel free to report it on GitHub.

Notable changes are:

  • HTTP client now supports HTTP/2.
  • Support of the new DATETIME type.
  • Improved type consistency in SQL.
  • Added transaction isolation levels.
  • Implemented fencing and pre-voting in RAFT.
  • Introduced foreign keys and constraints.

Compatibility

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Some changes are labeled as [Breaking change]. It means that the old behavior was considered error-prone and therefore changed to protect users from unintended mistakes. However, there is a small probability that someone can rely on the old behavior, and this label is to bring attention to the things that have been changed.

The changes that break backward compatibility are listed below:

Functionality added or changed

Core

  • The UUID field type is now part of the SCALAR field type (gh-6042).

  • The UUID field type is now available in SQL. A new UUID can be generated using the new SQL built-in UUID() function (gh-5886).

  • [Breaking change] The timeout() method of net.box connection, marked deprecated more than four years ago (in 1.7.4), has been dropped. It negatively affected the performance of hot net.box methods, such as call() and select() if they were called without specifying a timeout (gh-6242).

  • Improved net.box performance by up to 70% by rewriting hot code paths in C (gh-6241).

  • Introduced compact tuples that allow saving 4 bytes per tuple in case of small user data (gh-5385).

  • Now streams and interactive transactions over streams are implemented in iproto. Every stream is associated with its ID, which is unique within one connection. All requests with the same non-zero stream ID belong to the same stream. All requests in the stream are processed synchronously. The next request will not start executing until the previous one is completed. If a request’s stream ID is 0, it does not belong to a stream and is processed in the old way.

    In net.box, a stream is an object above the connection that has the same methods but allows executing requests sequentially. The ID is generated on the client-side automatically. If a user writes his own connector and wants to use streams, they must transmit the stream_id over the iproto protocol.

    The primary purpose of streams is transactions via iproto. As each stream can start a transaction, several transactions can be multiplexed over one connection. There are multiple ways to begin, commit, and rollback a transaction. One can do that using the appropriate stream methods, call, eval, or execute with the SQL transaction syntax. Users can mix these methods. For example, one might start a transaction using stream:begin(), and commit it with stream:call('box.commit') or stream:execute('COMMIT').

    If any request fails during the transaction, it will not affect the other requests in the transaction. If a disconnect occurs while there is an active transaction in the stream, that transaction will be rolled back if it hasn’t been committed before the connection failure (gh-5860).

  • Added the new memtx_allocator option to box.cfg{}. It allows selecting the appropriate allocator for memtx tuples if necessary. The possible values are system for malloc allocator and small for the default small allocator.

    Implemented the system allocator based on malloc. The slab allocator, which is used for tuple allocation, has a particular disadvantage – it is prone to unresolvable fragmentation on specific workloads (size migration). In this case, the user should be able to choose another allocator. The system allocator is based on the malloc function but restricted by the same quota as the slab allocator. The system allocator does not alloc all the memory at the start. Instead, it allocates memory as needed, checking that the quota is not exceeded (gh-5419).

  • Added box.stat.net.thread() for reporting per thread net statistics (gh-6293).

  • Added the new STREAMS metric to box.stat.net. It contains statistics for iproto streams. The STREAMS contains the same counters as the CONNECTIONS metric in box.stat.net: current, RPS, and total (gh-6293).

  • Extended the network protocol (IPROTO) with a new request type (IPROTO_ID). It is supposed to be used for exchanging sets of supported features between the server and client (gh-6253).

  • Added required_protocol_version and required_protocol_features to net.box connection options. The new options allow specifying the IPROTO protocol version and features that must be supported by the server for the connection to pass (gh-6253).

  • [Breaking change] Added the msgpack.cfg.encode_error_as_ext configuration option to enable/disable encoding errors as MP_ERROR MsgPack extension. The option is enabled by default (gh-6433).

  • [Breaking change] Removed box.session.setting.error_marshaling_enabled. Error marshalling is now enabled automatically if the connector supports it (gh-6428).

  • Added the new REQUESTS_IN_PROGRESS and REQUESTS_IN_STREAM_QUEUE metrics to box.stat.net that contains detailed statistics for iproto requests. These metrics contain the same counters as other metrics in box.stat.net: current, RPS, and total (gh-6293).

  • Implemented a timeout for fiber:join in Lua (gh-6203).

  • Updated libev to version 4.33 (gh-4909).

  • Added the new box.txn_id() function. It returns the ID of the current transaction if called within a transaction, nil otherwise.

  • Previously, if a yield occurs for a transaction that does not support it, all its statements are rolled back but still its new statements are processed (they will roll back with each yield). Also, the transaction will be rolled back when a commit is attempted. Now we stop processing any new statements right after the first yield if a transaction does not support it.

  • Implemented a timeout for transactions after which they are rolled back (gh-6177).

  • Implemented the new C API box_txn_set_timeout function to set a timeout for transactions.

  • Implemented a timeout for iproto transactions after which they are rolled back (gh-6177).

  • Implemented the new IPROTO_TIMEOUT 0x56 key, which is used to set a timeout for transactions over iproto streams. It is stored in the body of IPROTO_BEGIN request.

  • Introduced box.broadcast and box.watch functions to signal/watch user-defined state changes (gh-6257).

  • Added watchers support to the network protocol (gh-6257).

  • Added watchers support to the net.box connector (gh-6257).

  • Now error objects with the code box.error.READONLY now have the additional fields explaining why the error happened.

    Also, there is a new field box.info.ro_reason. It is nil on a writable instance, but reports a reason when box.info.ro is true (gh-5568).

  • Implemented the ability to open several listening sockets. In addition to the ability to pass uri as a number or string, added the ability to pass uri as a table of numbers or strings (gh-3554).

  • [Breaking change] net.box console support, which was marked deprecated in 1.10, has been dropped. Use require('console').connect() instead.

  • Added the takes_raw_args Lua function option for wrapping arguments in msgpack.object to skip decoding (gh-3349).

  • Implemented the graceful shutdown protocol for IPROTO connections (gh-5924).

  • Added fetch_schema flag to netbox.connect to control schema fetching from remote instance (gh-4789).

  • Added linking type (dynamic or static) to Tarantool build info.

  • Changed log level of some information messages from critical to info (gh-4675).

  • Added predefined system events: box.status, box.id, box.election, and box.schema (gh-6260).

  • Introduced transaction isolation levels in Lua and IPROTO (gh-6930).

  • Added support for backtrace feature on AARCH64 architecture (gh-6060).

  • Implemented collection of parent backtrace for the newly created fibers. To enable the feature, call fiber.parent_backtrace_enable. To disable it, call fiber.parent_backtrace_disable: disabled by default (gh-4302).

Memtx

  • Introduced memtx MVCC memory monitoring (gh-6150).

Vinyl

  • Disabled the deferred DELETE optimization in Vinyl to avoid possible performance degradation of secondary index reads. Now, to enable the optimization, one has to set the defer_deletes flag in space options (gh-4501).

Replication

  • Introduced box.info.replication[n].downstream.lag field to monitor the state of replication. This member represents a lag between the main node writing a certain transaction to its own WAL and the moment it receives an ack for this transaction from a replica (gh-5447).
  • Introduced on_election triggers. The triggers may be registered via box.ctl.on_election() interface and are run asynchronously each time box.info.election changes (gh-5819).
  • It is now possible to decode incoming replication data in a separate thread. Added the replication_threads configuration option that controls how many threads may be spawned to do the task (default is 1) (gh-6329).

Raft

  • Added the term field to box.info.synchro.queue. It contains a term of the last PROMOTE. It is usually equal to box.info.election.term but may be less than the election term when the new round of elections started, but no one promoted yet.
  • Servers with elections enabled won’t start new elections as long as at least one of their peers sees the current leader. They also won’t start the elections when they don’t have a quorum of connected peers. This should reduce cases when a server that has lost connectivity to the leader disrupts the whole cluster by starting new elections (gh-6654).
  • Added the leader_idle field to box.info.election table. The value shows time in seconds since the last communication with a known leader (gh-6654).

LuaJIT

  • Introduced support for LJ_DUALNUM mode in luajit-gdb.py (gh-6224).

  • Introduced preliminary support of GNU/Linux ARM64 and macOS M1. In the scope of this activity, the following issues have been resolved:

    • Introduced support for a full 64-bit range of lightuserdata values (gh-2712).
    • Fixed memory remapping issue when the page leaves 47-bit segments.
    • Fixed M1 architecture detection (gh-6065).
    • Fixed variadic arguments handling in FFI on M1 (gh-6066).
    • Fixed table.move misbehavior when table reallocation occurs (gh-6084).
    • Fixed Lua stack inconsistency when xpcall is called with an invalid second argument on ARM64 (gh-6093).
    • Fixed BC_USETS bytecode semantics for closed upvalues and gray strings.
    • Fixed side exit jump target patching considering the range values of the particular instruction (gh-6098).
    • Fixed current Lua coroutine restoring on an exceptional path on ARM64 (gh-6189).

  • Now memory profiler records allocations from traces grouping them by the trace number (gh-5814). The memory profiler parser can display the new type of allocation sources in the following format:

    | TRACE [<trace-no>] <trace-addr> started at @<sym-chunk>:<sym-line>

  • Now the memory profiler reports allocations made by the JIT engine while compiling the trace as INTERNAL (gh-5679).

  • Now the memory profiler emits events of the new type when a function or a trace is created. As a result, the memory profiler parser can enrich its symbol table with the new functions and traces (gh-5815).

    Furthermore, there are symbol generations introduced within the internal parser structure to handle possible collisions of function addresses and trace numbers.

  • Now the memory profiler dumps symbol table for C functions. As a result, memory profiler parser can enrich its symbol table with C symbols (gh-5813). Furthermore, now memory profiler dumps special events for symbol table when it encounters a new C symbol, that has not been dumped yet.

  • Introduced the LuaJIT platform profiler (gh-781) and the profile parser. This profiler is able to capture both host and VM stacks, so it can show the whole picture. Both C and Lua API’s are available for the profiler. Profiler comes with the default parser, which produces output in a flamegraph.pl-suitable format. The following profiling modes are available:

    • Default: only virtual machine state counters.
    • Leaf: shows the last frame on the stack.
    • Callchain: performs a complete stack dump.

Lua

  • Introduced the new method table.equals. It compares two tables by value and respects the __eq metamethod.

  • Added support of console autocompletion for net.box objects stream and future (gh-6305).

  • Added the box.runtime.info().tuple metric to track the amount of memory occupied by tuples allocated on runtime arena (gh-5872).

    It does not count tuples that arrive from memtx or vinyl but counts tuples created on-the-fly: say, using box.tuple.new(<...>).

Datetime

  • Added a new built-in module datetime.lua that allows operating timestamps and intervals values (gh-5941).

  • Added the method to allow converting string literals in extended iso-8601 or rfc3339 formats (gh-6731).

  • Extended the range of supported years in all parsers to cover fully -5879610-06-22..5879611-07-11 (gh-6731).

  • Datetime interval support has been reimplemented in C to make possible future Olson/tzdata and SQL extensions (gh-6923).

    Now all components of the interval values are kept and operated separately (years, months, weeks, days, hours, seconds, and nanoseconds). This allows applying date/time arithmetic correctly when we add/subtract intervals to datetime values.

  • Extended datetime literal parser with the ability to handle known timezone abbreviations (‘MSK’, ‘CET’, etc.) which are deterministically translated to their offset (gh-5941, gh-6751).

    Timezone abbreviations can be used in addition to the timezone offset in the datetime literals. For example, these literals produce equivalent datetime values:

    local date = require('datetime')
local d1 = date.parse('2000-01-01T02:00:00+0300')
local d2 = date.parse('2000-01-01T02:00:00 MSK')
local d3 = date.parse('2000-01-01T02:00:00 MSK', {format = '%FT%T %Z'})

    Parser fails if one uses ambiguous names (for example, ‘AT’) which could not be directly translated into timezone offsets.

  • Enabled support for timezone names in the constructor and date:set{} modifier via tz attribute. Currently, only timezone name abbreviations are supported (gh-7076).

    Timezone abbreviations can be used in addition to the timezone offset. They can be used during constructing or modifying a date object, or while parsing datetime literals. Numeric time offsets and named abbreviations produce equivalent datetime values:

    local date = require('datetime')
local d2 = date.parse('2000-01-01T02:00:00 MSK')

local d1 = date.new{year = 1980, tz = 'MSK'}
d2 = date.new{year = 1980, tzoffset = 180}
d2:set{tz = 'MSK'}

    Note that the timezone name parser fails if one uses ambiguous names, which could not be translated into timezone offsets directly (for example, ‘AT’).

Digest

  • Introduced new hash types in digest module – xxhash32 and xxhash64 (gh-2003).

Fiber

  • Introduced fiber_object:info() to get info from fiber. Works as require('fiber').info() but only for one fiber.
  • Introduced fiber_object:csw() to get csw from fiber (gh-5799).
  • Changed fiber.info() to hide backtraces of idle fibers (gh-4235).
  • Improved fiber fiber.self(), fiber.id() and fiber.find() performance by 2-3 times.

Log

  • Implemented support of symbolic log levels representation in log module (gh-5882). Now it is possible to specify levels the same way as in box.cfg{} call.

    For example, instead of

    require('log').cfg{level = 6}

    one can use

    require('log').cfg{level = 'verbose'}

Msgpack

Netbox

  • Added the return_raw net.box option for returning msgpack.object instead of decoding the response (gh-4861).

Schema

  • is_multikey option may now be passed to box.schema.func.create directly, without opts sub-table.

SQL

  • Descriptions of type mismatch error and inconsistent type error became more informative (gh-6176).
  • Removed explicit cast from BOOLEAN to numeric types and vice versa (gh-4770).
  • Removed explicit cast from VARBINARY to numeric types and vice versa (gh-4772, gh-5852).
  • Fixed a bug due to which a string that is not NULL-terminated could not be cast to BOOLEAN, even if the conversion should be successful according to the rules.
  • Now a numeric value can be cast to another numeric type only if the cast is precise. In addition, a UUID value cannot be implicitly cast to STRING/VARBINARY. Also, a STRING/VARBINARY value cannot be implicitly cast to a UUID (gh-4470).
  • Now any number can be compared to any other number, and values of any scalar type can be compared to any other value of the same type. A value of a non-numeric scalar type cannot be compared with a value of any other scalar type (gh-4230).
  • SQL built-in functions were removed from the _func system space (gh-6106).
  • Functions are now looked up first in SQL built-in functions and then in user-defined functions.
  • Fixed incorrect error message in case of misuse of the function used to set the default value.
  • The typeof() function with NULL as an argument now returns NULL (gh-5956).
  • The SCALAR and NUMBER types have been reworked in SQL. Now SCALAR values cannot be implicitly cast to any other scalar type, and NUMBER values cannot be implicitly cast to any other numeric type. This means that arithmetic and bitwise operations and concatenation are no longer allowed for SCALAR and NUMBER values. In addition, any SCALAR value can now be compared with values of any other scalar type using the SCALAR rules (gh-6221).
  • The DECIMAL field type is now available in SQL. Decimal can be implicitly cast to and from INTEGER and DOUBLE, it can participate in arithmetic operations and comparison between DECIMAL, and all other numeric types are defined (gh-4415).
  • The argument types of SQL built-in functions are now checked in most cases during parsing. In addition, the number of arguments is now always checked during parsing (gh-6105).
  • DECIMAL values can now be bound in SQL (gh-4717).
  • A value consisting of digits and a decimal point is now parsed as DECIMAL (gh-6456).
  • The ANY field type is now available in SQL (gh-3174).
  • Built-in SQL functions now work correctly with DECIMAL values (gh-6355).
  • The default type is now defined in case the argument type of an SQL built-in function cannot be determined during parsing (gh-4415).
  • The ARRAY field type is now available in SQL. The syntax has also been implemented to allow the creation of ARRAY values (gh-4762).
  • User-defined aggregate functions are now available in SQL (gh-2579).
  • Introduced SQL built-in functions NOW() and DATE_PART() (gh-6773).
  • The left operand is now checked before the right operand in an arithmetic operation. (gh-6773).
  • The INTERVAL field type is introduced in SQL (gh-6773).
  • Bitwise operations can now only accept UNSIGNED and positive INTEGER values (gh-5364).
  • The MAP field type is now available in SQL. Also, the syntax has been implemented to allow the creation of MAP values (gh-4763).
  • Introduced [] operator for MAP and ARRAY values (gh-6251).

Box

  • Public role now has read, write access on _session_settings space (gh-6310).
  • The INTERVAL field type is introduced to BOX (gh-6773).
  • The behavior of empty or nil select calls on user spaces was changed. A critical log entry containing the current stack traceback is created upon such function calls. The user can explicitly request a full scan though by passing fullscan=true to select ’s options table argument, in which case a log entry will not be created (gh-6539).
  • Improved checking for dangerous select calls. The calls with offset + limit <= 1000 are now considered safe, which means a warning is not issued. The ‘ALL’, ‘GE’, ‘GT’, ‘LE’, ‘LT’ iterators are now considered dangerous by default even with the key present (gh-7129).

Datetime

  • Allowed using human-readable timezone names (for example, ‘Europe/Moscow’) in datetime strings. Use IANA tzdata (Olson DB) for timezone-related operations, such as DST-based timezone offset calculations (gh-6751).
  • The isdst field in the datetime object is now calculated correctly, according to the IANA tzdata (aka Olson DB) rules for the given date/time moment (gh-6751).
  • The datetime module exports the bidirectional TZ array, which can be used to translate the timezone index (tzindex) into timezone names, and vice versa (gh-6751).

Fiber

  • Previously csw (Context SWitch) of a new fiber could be more than 0, now it is always 0 (gh-5799).

Luarocks

  • Set FORCE_CONFIG=false for luarocks config to allow loading project-side .rocks/config-5.1.lua.

Xlog

  • Reduced snapshot verbosity (gh-6620).

Build

  • Support fedora-34 build (gh-6074).
  • Stopped support fedora-28 and fedora-29.
  • Stopped support of Ubuntu Trusty (14.04) (gh-6502).
  • Bumped Debian package compatibility level to 10 (gh-5429).
  • Bumped minimal required debhelper to version 10 (except for Ubuntu Xenial).
  • Removed Windows binaries from Debian source packages (gh-6390).
  • Bumped Debian control Standards-Version to 4.5.1 (gh-6390).
  • Added bundling of libnghttp2 for bundled libcurl to support HTTP/2 for http client. The CMake version requirement is updated from 3.2 to 3.3.
  • Support fedora-35 build (gh-6692).
  • Added bundling of GNU libunwind to support backtrace feature on AARCH64 architecture and distributives that don’t provide libunwind package.
  • Re-enabled backtrace feature for all RHEL distributions by default, except for AARCH64 architecture and ancient GCC versions, which lack compiler features required for backtrace (gh-4611).
  • Updated libicu version to 71.1 for static build.
  • Bumped OpenSSL from 1.1.1f to 1.1.1n for static build (gh-6947).
  • Updated libcurl to version 7.83.0 (gh-6029).
  • Support Fedora-36 build.
  • Support Ubuntu Jammy (22.04) build.

Bugs fixed

Core

  • [Breaking change] fiber.wakeup() in Lua and fiber_wakeup() in C became NOP on the currently running fiber.

    Previously they allowed ignoring the next yield or sleep, which resulted in unexpected erroneous wake-ups. Calling these functions right before fiber.create() in Lua or fiber_start() in C could lead to a crash (in debug build) or undefined behaviour (in release build) (gh-6043).

    There was a single use case for that—reschedule in the same event loop iteration which is not the same as fiber.sleep(0) in Lua and fiber_sleep(0) in C. It could be done in the following way:

    in C:

    fiber_wakeup(fiber_self());
fiber_yield();

    in Lua:

    fiber.self():wakeup()
fiber.yield()

    To get the same effect in C, one can use fiber_reschedule(). In Lua, it is now impossible to reschedule the current fiber directly in the same event loop iteration. One can reschedule self through a second fiber, but it is strongly discouraged:

    local self = fiber.self()
fiber.new(function() self:wakeup() end)
fiber.sleep(0)

  • Fixed memory leak on each box.on_commit() and box.on_rollback() (gh-6025).

  • Fixed the lack of testing for non-joinable fibers in fiber_join() call. This could lead to unpredictable results. Note the issue affects C level only, in Lua interface fiber:join() the protection is turned on already.

  • Now Tarantool yields when scanning .xlog files for the latest applied vclock and when finding the right place in .xlogs to start recovering. This means that the instance is responsive right after box.cfg call even when an empty .xlog was not created on the previous exit. Also, this prevents the relay from timing out when a freshly subscribed replica needs rows from the end of a relatively long (hundreds of MBs) .xlog (gh-5979).

  • The counter in x.yM rows processed log messages does not reset on each new recovered xlog anymore.

  • Fixed wrong type specification when printing fiber state change which led to negative fiber’s ID logging (gh-5846).

    For example,

    main/-244760339/cartridge.failover.task I> Instance state changed

    instead of proper

    main/4050206957/cartridge.failover.task I> Instance state changed

  • Fiber IDs were switched to monotonically increasing unsigned 8-byte integers so that there would not be IDs wrapping anymore. This allows detecting fiber’s precedence by their IDs if needed (gh-5846).

  • Fixed a crash in JSON update on tuple/space when it had more than one operation, they accessed fields in reversed order, and these fields did not exist. Example: box.tuple.new({1}):update({{'=', 4, 4}, {'=', 3, 3}}) (gh-6069).

  • Fixed invalid results produced by the json module’s encode function when it was used from Lua’s garbage collector. For instance, in functions used as ffi.gc() (gh-6050).

  • Added check for user input of the number of iproto threads—value must be > 0 and less than or equal to 1000 (gh-6005).

  • Fixed error related to the fact that if a user changed the listen address, all iproto threads closed the same socket multiple times.

  • Fixed error related to Tarantool not deleting the unix socket path when the work is finished.

  • Fixed a crash in MVCC during simultaneous update of a key in different transactions (gh-6131).

  • Fixed a bug when memtx MVCC crashed during reading uncommitted DDL (gh-5515).

  • Fixed a bug when memtx MVCC crashed if an index was created in the transaction (gh-6137).

  • Fixed segmentation fault with MVCC when an entire space was updated concurrently (gh-5892).

  • Fixed a bug with failed assertion after stress update of the same key (gh-6193).

  • Fixed a crash that happened when a user called box.snapshot during an incomplete transaction (gh-6229).

  • Fixed console client connection breakage if request times out (gh-6249).

  • Added missing broadcast to net.box.future:discard(). Now fibers waiting for a request result are woken up when the request is discarded (gh-6250).

  • box.info.uuid, box.info.cluster.uuid, and tostring(decimal) with any decimal number in Lua sometimes could return garbage if __gc handlers were used in the user’s code (gh-6259).

  • Fixed the error message that happened in a very specific case during MVCC operation (gh-6247).

  • Fixed a repeatable read violation after delete (gh-6206).

  • Fixed a bug when hash select{} was not tracked by MVCC engine (gh-6040).

  • Fixed a crash in MVCC after the drop of a space with several indexes (gh-6274).

  • Fixed a bug when GC at some state could leave tuples in secondary indexes (gh-6234).

  • Disallowed yields after DDL operations in MVCC mode. It fixes a crash which takes place in case several transactions refer to system spaces (gh-5998).

  • Fixed a bug in MVCC connected which happened on a rollback after DDL operation (gh-5998).

  • Fixed a bug when rollback resulted in unserializable behaviour (gh-6325).

  • At the moment, when a net.box connection is closed, all requests that have not been sent will be discarded. This patch fixes this behavior: all requests queued for sending before the connection is closed are guaranteed to be sent (gh-6338).

  • Fixed a crash during replace of malformed tuple into _schema system space (gh-6332).

  • Fixed dropping incoming messages when the connection is closed or SHUT_RDWR received and net_msg_max or readahead limit is reached (gh-6292).

  • Fixed memory leak in case of replace during background alter of the primary index (gh-6290).

  • Fixed a bug when rolled back changes appear in the built-in-background index (gh-5958).

  • Fixed a crash while encoding an error object in the MsgPack format (gh-6431).

  • Fixed a bug when an index was inconsistent after background build in case the primary index was hash (gh-5977).

  • Now inserting a tuple with the wrong id` field into the _priv space returns the correct error (gh-6295).

  • Fixed dirty read in MVCC after space alter (gh-6263, gh-6318).

  • Fixed a crash in case the fiber changing box.cfg.listen is woken up (gh-6480).

  • Fixed box.cfg.listen not reverted to the old address in case the new one is invalid (gh-6092).

  • Fixed a crash caused by a race between box.session.push() and closing connection (gh-6520).

  • Fixed a bug because of which the garbage collector could remove an xlog file that was still in use (gh-6554).

  • Fixed crash during granting privileges from guest (gh-5389).

  • Fixed an error in listening when the user passed uri in numerical form after listening unix socket (gh-6535).

  • Fixed a crash that could happen in case a tuple is deleted from a functional index while there is an iterator pointing to it (gh-6786).

  • Fixed memory leak in interactive console (gh-6817).

  • Fixed an assertion fail when passing a tuple without primary key fields to before_replace trigger. Now tuple format is checked before execution of before_replace triggers and after each one (gh-6780).

  • Banned DDL operations in space on_replace triggers, since they could lead to a crash (gh-6920).

  • Implemented constraints and foreign keys. Now users can create function constraints and foreign key relations (gh-6436).

  • Fixed a bug due to which all fibers created with fiber_attr_setstacksize() leaked until the thread exit. Their stacks also leaked except when fiber_set_joinable(..., true) was used.

  • Fixed a crash in MVCC related to a secondary index conflict (gh-6452).

  • Fixed a bug which resulted in wrong space count (gh-6421).

  • SELECT in RO transaction now reads confirmed data, like a standalone (autocommit) SELECT does (gh-6452).

  • Fixed a crash when Tarantool was launched with multiple -e or -l options without a space between the option and the value (gh-5747).

  • Fixed effective session and user not propagated to box.on_commit and box.on_rollback trigger callbacks (gh-7005).

  • Fixed usage of box.session.peer() in box.session.on_disconnect() trigger. Now it’s safe to assume that box.session.peer() returns the address of the disconnected peer, not nil, as it used to (gh-7014).

  • Fixed creation of a space with a foreign key pointing to the same space (gh-6961).

  • Fixed a bug when MVCC failed to track nothing-found range select (gh-7025).

  • Allowed complex foreign keys with NULL fields (gh-7046).

  • Added decoding of election messages: RAFT and PROMOTE to xlog Lua module (gh-6088). Otherwise tarantoolctl shows plain number in type

    HEADER:
  lsn: 1
  replica_id: 4
  type: 31
  timestamp: 1621541912.4592

    instead of symbolic representation

    HEADER:
  lsn: 1
  replica_id: 4
  type: PROMOTE
  timestamp: 1621541912.4592

  • [Breaking change] Return value signedness of 64-bit time functions in clock and fiber was changed from uint64_t to int64_t both in Lua and C (gh-5989).

  • Fixed reversed iterators gap tracking. Instead of tracking gaps for the successors of keys, gaps for tuples shifted by one to the left of the successor were tracked (gh-7113).

Memtx

  • Now memtx raises an error if the “clear” dictionary is passed to s:select() (gh-6167).
  • Fixed MVCC transaction manager story garbage collection breaking memtx TREE index iterator (gh-6344).

Vinyl

  • Fixed possible keys divergence during secondary index build, which might lead to missing tuples (gh-6045).
  • Fixed the race between Vinyl garbage collection and compaction that resulted in a broken vylog and recovery failure (gh-5436).
  • Immediate removal of compacted run files created after the last checkpoint optimization now works for replica’s initial JOIN stage (gh-6568).
  • Fixed crash during recovery of a secondary index in case the primary index contains incompatible phantom tuples (gh-6778).

Replication

  • Fixed the use after free in the relay thread when using elections (gh-6031).
  • Fixed a possible crash when a synchronous transaction was followed by an asynchronous transaction right when its confirmation was being written (gh-6057).
  • Fixed an error where a replica, while attempting to subscribe to a foreign cluster with a different replicaset UUID, did not notice it is impossible and instead became stuck in an infinite retry loop printing a TOO_EARLY_SUBSCRIBE error (gh-6094).
  • Fixed an error where a replica, while attempting to join a cluster with exclusively read-only replicas available, just booted its own replicaset, instead of failing or retrying. Now it fails with an error about the other nodes being read-only so they can’t register the new replica (gh-5613).
  • Fixed error reporting associated with transactions received from remote instances via replication. Any error raised while such a transaction was being applied was always reported as Failed to write to disk regardless of what really happened. Now the correct error is shown. For example, Out of memory, or Transaction has been aborted by conflict, and so on (gh-6027).
  • Fixed replication stopping occasionally with ER_INVALID_MSGPACK when replica is under high load (gh-4040).
  • Fixed a cluster that sometimes could not bootstrap if it contained nodes with election_mode manual or voter (gh-6018).
  • Fixed a possible crash when box.ctl.promote() was called in a cluster with >= 3 instances, happened in debug build. In release build, it could lead to undefined behavior. It was likely to happen if a new node was added shortly before the promotion (gh-5430).
  • Fixed a rare error appearing when MVCC (box.cfg.memtx_use_mvcc_engine) was enabled and more than one replica was joined to a cluster. The join could fail with the error "ER_TUPLE_FOUND: Duplicate key exists in unique index 'primary' in space '_cluster'". The same could happen at the bootstrap of a cluster having >= 3 nodes (gh-5601).
  • Fixed replica reconnecting to a living master on any box.cfg{replication=...} change. Such reconnects could lead to replica failing to restore connection for replication_timeout seconds (gh-4669).
  • Fixed potential obsolete data write in synchronous replication due to race in accessing terms while disk write operation is in progress and not yet completed.
  • Fixed replicas failing to bootstrap when the master has just restarted (gh-6966).
  • Fixed a bug when replication was broken on the master side with ER_INVALID_MSGPACK (gh-7089).

Raft

  • Fixed box.ctl.promote() entering an infinite election loop when a node does not have enough peers to win the elections (gh-6654).
  • Servers with elections enabled will resign the leadership and become read-only when the number of connected replicas becomes less than a quorum. This should prevent split-brain in some situations (gh-6661).
  • Fixed a rare crash with the leader election enabled (any mode except off), which could happen if a leader resigned from its role at the same time as some other node was writing something related to the elections to WAL. The crash was in debug build. In the release build, it would lead to undefined behavior (gh-6129).
  • Fixed an error when a new replica in a Raft cluster could try to join from a follower instead of a leader and failed with an error ER_READONLY (gh-6127).
  • Reconfiguration of box.cfg.election_timeout could lead to a crash or undefined behavior if done during an ongoing election with a special WAL write in progress.
  • Fixed several crashes and/or undefined behaviors (assertions in debug build) which could appear when new synchronous transactions were made during ongoing elections (gh-6842).

LuaJIT

  • Fixed optimization for single-char strings in the IR_BUFPUT assembly routine.
  • Fixed slots alignment in lj-stack command output when LJ_GC64 is enabled (gh-5876).
  • Fixed dummy frame unwinding in lj-stack command.
  • Fixed top part of Lua stack (red zone, free slots, top slot) unwinding in lj-stack command.
  • Added the value of g->gc.mmudata field to lj-gc output.
  • Fixed detection of inconsistent renames even in the presence of sunk values (gh-4252, gh-5049, gh-5118).
  • Fixed the order VM registers are allocated by LuaJIT frontend in case of BC_ISGE and BC_ISGT (gh-6227).
  • Fixed inconsistency while searching for an error function when unwinding a C-protected frame to handle a runtime error (an error in __gc handler).
  • string.char() builtin recording is fixed in case when no arguments are given (gh-6371, gh-6548).
  • Actually made JIT respect maxirconst trace limit while recording (gh-6548).

Lua

  • Fixed a bug when multibyte characters broke space:fselect() output.
  • When an error is raised during encoding call results, the auxiliary lightuserdata value is not removed from the main Lua coroutine stack. Prior to the fix, it leads to undefined behavior during the next usage of this Lua coroutine (gh-4617).
  • Fixed Lua C API misuse, when the error is raised during call results encoding on unprotected coroutine and expected to be caught on the different one that is protected (gh-6248).
  • Fixed net.box error in case connections are frequently opened and closed (gh-6217).
  • Fixed incorrect handling of variable number of arguments in box.func:call() (gh-6405).
  • Fixed table.equals result when booleans compared (gh-6386).
  • Tap subtests inherit strict mode from parent (gh-6868).
  • Fixed the behavior of Tarantool console on SIGINT. Now Ctrl+C discards the current input and prints the new prompt (gh-2717).

Triggers

  • Fixed the possibility of a crash in case when trigger removes itself.
  • Fixed the possibility of a crash in case someone destroys trigger when it’s yielding (gh-6266).

SQL

  • User-defined functions can now return VARBINARY to SQL as a result (gh-6024).
  • Fixed assert on a cast of DOUBLE value greater than -1.0 and less than 0.0 to INTEGER and UNSIGNED (gh-6255).
  • Removed spontaneous conversion from INTEGER to DOUBLE in a field of type NUMBER (gh-5335).
  • All arithmetic operations can now only accept numeric values (gh-5756).
  • Now function quote() returns an argument in case the argument is DOUBLE. The same for all other numeric types. For types other than numeric, STRING is returned (gh-6239).
  • The TRIM() function now does not lose collation when executed with the keywords BOTH, LEADING, or TRAILING (gh-6299).
  • Now getting unsupported msgpack extension in SQL throws the correct error (gh-6375).
  • Now, when copying an empty string, an error will not be set unnecessarily (gh-6157, gh-6399).
  • Fixed wrong comparison between DECIMAL and large DOUBLE values (gh-6376).
  • Fixed truncation of DECIMAL during implicit cast to INTEGER in LIMIT and OFFSET.
  • Fixed truncation of DECIMAL during implicit cast to INTEGER when value is used in an index.
  • Fixed assert on a cast of DECIMAL value that is greater than -1.0 and less than 0.0 to INTEGER (gh-6485).
  • The HEX() SQL built-in function no longer throws an assert when its argument consists of zero-bytes (gh-6113).
  • LIMIT is now allowed in ORDER BY where sort order is in both directions (gh-6664).
  • Fixed a memory leak in SQL during calling of user-defined function (gh-6789).
  • Fixed assertion or segmentation fault when MP_EXT received via net.box (gh-6766).
  • Now the ROUND() function properly supports INTEGER and DECIMAL as the first argument (gh-6988).
  • Fixed a crash when a table inserted data into itself with an incorrect number of columns (gh-7132).

Box

  • Fixed log.cfg getting updated on box.cfg error (gh-6086).
  • Fixed the error message in an attempt to insert into a tuple the size of which equals to box.schema.FIELD_MAX (gh-6198).
  • We now check that all privileges passed to box.schema.grant are resolved (gh-6199).
  • Added iterator type checking and allow passing iterator as a box.index.{ALL,GT,...} directly (gh-6501).

Datetime

  • Intervals received after datetime arithmetic operations may be improperly normalized if the result was negative

    tarantool> date.now() - date.now()
---
- -1.000026000 seconds
...

    It means that two immediately called date.now() produce very close values, which difference should be close to 0, not 1 second (gh-6882).

  • Fixed a bug in datetime module when date:set{tzoffset=XXX} did not produce the same result with date.new{tzoffset=XXX} for the same set of attributes passed (gh-6793).

HTTP client

  • Fixed invalid headers after redirect (gh-6101).

Mvcc

  • Fixed MVCC interaction with ephemeral spaces: TX manager now ignores such spaces (gh-6095).
  • Fixed a loss of tuple after a conflict exception (gh-6132).
  • Fixed a segmentation fault in update/delete of the same tuple (gh-6021).

Net.box

  • Changed the type of the error returned by net.box on timeout from ClientError to TimedOut (gh-6144).

Recovery

  • When force_recovery cfg option is set, Tarantool is able to boot from snap/xlog combinations where xlog covers changes committed both before and after snap creation. For example, 0...0.xlog, covering everything up to vclock {1: 15} and 0...09.snap, corresponding to vclock {1: 9} (gh-6794).

Tarantoolctl

  • Fixed the missing rocks keyword in tarantoolctl rocks help messages.

Build

  • Bumped Debian packages tarantool-common dependency to use luarocks 3 (gh-5429).
  • Fixed an error when it was possible to have new Tarantool package (version >= 2.2.1) installed with pre-luarocks 3 tarantool-common package (version << 2.2.1), which caused rocks install to fail.
  • The Debian package does not depend on binutils anymore (gh-6699).
  • Fixed build errors with glibc-2.34 (gh-6686).
  • Changed size of alt. signal stack for ASAN needs.
  • Fixed build errors on arm64 with CMAKE_BUILD_TYPE=Debug.

Tarantool 2.8.4

Released on 2022-04-25.

Overview

2.8.4 is the third stable version of the 2.8 release series. It introduces 1 improvement and resolves 16 bugs since version 2.8.3.

The “stable” label means that we have all planned features implemented and we see no high-impact issues. However, if you encounter an issue, feel free to report it on GitHub.

Compatibility

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Functionality added or changed

Build

  • Support fedora-35 build (gh-6692).

Bugs fixed

Core

  • Fixed a crash that could happen in case a tuple is deleted from a functional index while there is an iterator pointing to it (gh-6786).
  • Fixed memory leak in interactive console (gh-6817).
  • Fixed an assertion fail when passing tuple without primary key fields to before_replace trigger. Now tuple format is checked before execution of before_replace triggers and after each one (gh-6780).
  • Banned DDL operations in space on_replace triggers, since they could lead to a crash (gh-6920).
  • Fixed a bug due to which all fibers created with fiber_attr_setstacksize() leaked until the thread exit. Their stacks also leaked except when fiber_set_joinable(..., true) was used.

Vinyl

  • Immediate removal of compacted run files created after the last checkpoint optimization now works for replica’s initial JOIN stage (gh-6568).
  • Fixed crash during recovery of a secondary index in case the primary index contains incompatible phantom tuples (gh-6778).

Raft

  • Reconfiguration of box.cfg.election_timeout could lead to a crash or undefined behaviour if done during an ongoing election with a special WAL write in progress.

LuaJIT

  • Fixed top part of Lua stack (red zone, free slots, top slot) unwinding in lj-stack command.
  • Added the value of g->gc.mmudata field to lj-gc output.
  • string.char() builtin recording is fixed in case when no arguments are given (gh-6371, gh-6548).
  • Actually made JIT respect maxirconst trace limit while recording (gh-6548).

Lua

  • Fixed table.equals result when booleans compared (gh-6386).
  • Tap subtests inherit strict mode from parent (gh-6868).

Box

  • Added iterator type checking and allow to pass iterator as a box.index.{ALL,GT,…} directly (gh-6501).

HTTP client

  • Fixed invalid headers after redirect (gh-6101).

Recovery

  • When force_recovery cfg option is set, Tarantool is able to boot from snap/xlog combinations where xlog covers changes committed both before and after snap creation. For example, 0...0.xlog, covering everything up to vclock {1: 15} and 0...09.snap, corresponding to vclock {1: 9} (gh-6794).

Tarantool 2.8.3

Released on 2021-12-22.

Overview

2.8.3 is the third stable version of the 2.8 release series. It introduces 3 improvements and resolves 24 bugs since version 2.8.2.

The “stable” label means that we have all planned features implemented and we see no high-impact issues. However, if you encounter an issue, feel free to report it on GitHub.

Compatibility

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Functionality added or changed

LuaJIT

  • Introduced support for LJ_DUALNUM mode in luajit-gdb.py (gh-6224).

Build

  • Stop support of Ubuntu Trusty (14.04). (gh-6502)
  • Bump debian package compatibility level to 10 (gh-5429). Bump minimal required debhelper to version 10 (except for Ubuntu Xenial).

Bugs fixed

Core

  • Disallow yields after DDL operations in MVCC mode. It fixes crash which takes place in case several transactions refer to system spaces (gh-5998).
  • Fixed bug in MVCC connected which happens on rollback after DDL operation (gh-5998).
  • Fix a bug when rollback resulted in unserializable behaviour (gh-6325)
  • Fixed a crash during replace of malformed tuple into _schema system space (gh-6332).
  • Fix memory leak in case of replace during background alter of primary index (gh-6290)
  • Fix a bug when rollbacked changes appears in built-in-background index (gh-5958)
  • Fix a bug when index was inconsistent after background build in case when the primary index is hash (gh-5977)
  • Now inserting a tuple with the wrong “id” field into the _priv space will return the correct error (gh-6295).
  • Fixed dirty read in MVCC after space alter (gh-6263, gh-6318).
  • Fixed a crash caused by a race between box.session.push() and closing connection (gh-6520).
  • Fixed crash in case a fiber changing box.cfg.listen is woken up (gh-6480).
  • Fixed box.cfg.listen not reverted to the old address in case the new one is invalid (gh-6092).
  • Fixed a bug because of which the garbage collector could remove an xlog file that is still in use (gh-6554).
  • Fix crash during granting priveleges from guest (gh-5389).

Replication

  • Fixed replica reconnecting to a living master on any box.cfg{replication=...} change. Such reconnects could lead to replica failing to restore connection for replication_timeout seconds (gh-4669).

LuaJIT

  • Fixed the order VM registers are allocated by LuaJIT frontend in case of BC_ISGE and BC_ISGT (gh-6227).
  • Fixed inconsistency while searching for an error function when unwinding a C protected frame to handle a runtime error (e.g. an error in __gc handler).

Lua

  • When error is raised during encoding call results, auxiliary lightuserdata value is not removed from the main Lua coroutine stack. Prior to the fix it leads to undefined behaviour during the next usage of this Lua coroutine (gh-4617).
  • Fixed Lua C API misuse, when the error is raised during call results encoding on unprotected coroutine and expected to be catched on the different one, that is protected (gh-6248).
  • Fixed net.box error in case connections are frequently opened and closed (gh-6217).
  • Fixed incorrect handling of variable number of arguments in box.func:call() (gh-6405).

Triggers

  • Fixed possibility crash in case when trigger removes itself. Fixed possibility crash in case when someone destroy trigger, when it’s yield (gh-6266).

SQL

  • Now, when copying an empty string, an error will not be set unnecessarily (gh-6157, gh-6399).

Build

  • The Debian package does not depend on binutils anymore (gh-6699).
  • Fix build errors with glibc-2.34 (gh-6686).

Tarantool 2.8.2

Released on 2021-08-19.

Overview

2.8.2 is the second stable version of the 2.8 release series. It introduces 6 improvements and resolves 51 bugs since version 2.8.1.

The “stable” label means that we have all planned features implemented and we see no high-impact issues. However, if you encounter an issue, feel free to report it on GitHub.

Compatibility

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Functionality added or changed

LuaJIT

  • Introduced support for LJ_DUALNUM mode in luajit-gdb.py (gh-6224).

Lua

  • Introduced the new method table.equals. It compares two tables by value with respect to the __eq metamethod.

Logging

  • The log module now supports symbolic representation of log levels. Now it is possible to specify levels the same way as in the box.cfg{} call (gh-5882).

    For example, instead of

    require('log').cfg{level = 6}

    it is possible to use

    require('log').cfg{level = 'verbose'}

SQL

  • Descriptions of type mismatch error and inconsistent type error have become more informative (gh-6176).

  • Removed explicit cast from BOOLEAN to numeric types and vice versa (gh-4770).

    For example, CAST(FALSE AS INTEGER) was 0 in version 2.8. Now it causes an error.

  • Removed explicit cast from VARBINARY to numeric types and vice versa (gh-4772, gh-5852).

  • Fixed a bug where a string that is not NULL-terminated could not be cast to BOOLEAN, even if the conversion would be successful according to the rules.

Build

  • Fedora 34 builds are now supported (gh-6074).
  • Fedora 28 and 29 builds are no longer supported.

Bugs fixed

Core

  • [Breaking change] fiber.wakeup() in Lua and fiber_wakeup() in C became NOP on the currently running fiber. Previously they allowed “ignoring” the next yield or sleep, which resulted in unexpected erroneous wake-ups. Calling these functions right before fiber.create() in Lua or fiber_start() in C could lead to a crash (in debug build) or undefined behaviour (in release build) (gh-6043).

    There was a single use case for the previous behaviour: rescheduling in the same event loop iteration, which is not the same as fiber.sleep(0) in Lua and fiber_sleep(0) in C. It could be done in the following way:

    in C:

    fiber_wakeup(fiber_self());
fiber_yield();

    and in Lua:

    fiber.self():wakeup()
fiber.yield()

    To get the same effect in C, one can now use fiber_reschedule(). In Lua, it is now impossible to reschedule the current fiber directly in the same event loop iteration. One can reschedule self through a second fiber, but it is strongly discouraged:

    -- do not use this code
local self = fiber.self()
fiber.new(function() self:wakeup() end)
fiber.sleep(0)

  • Fixed memory leak on box.on_commit() and box.on_rollback() (gh-6025).

  • fiber_join() now checks if the argument is a joinable fiber. The absence of this check could lead to unpredictable results. Note that the change affects the C level only; in the Lua interface, fiber:join() protection is already enabled.

  • Now Tarantool yields when it scans .xlog files for the latest applied vclock and finds the right place to start recovering from. It means that the instance becomes responsive right after the box.cfg call even if an empty .xlog was not created on the previous exit.

    This fix also prevents the relay from timing out when a freshly subscribed replica needs rows from the end of a relatively long (hundreds of MBs) .xlog file (gh-5979).

  • The counter in N rows processed log messages no longer resets on each newly recovered xlog.

  • Fixed a crash in JSON update on tuple/space, where the update included two or more operations that accessed fields in reversed order and these fields didn’t exist. Example: box.tuple.new({1}):update({{'=', 4, 4}, {'=', 3, 3}}) (gh-6069).

  • Fixed invalid results of the json module’s encode function when it was used from the Lua garbage collector. For example, this could happen in functions used as ffi.gc() (gh-6050).

  • Added a check for user input of the number of iproto threads: value must be greater than zero and less than or equal to 1000 (gh-6005).

  • Changing a listed address can no longer cause iproto threads to close the same socket several times.

  • Tarantool now always removes the Unix socket correctly when it exits.

  • Simultaneously updating a key in different transactions does not longer result in a MVCC crash (gh-6131).

  • Fixed a bug where memtx MVCC crashed during reading uncommitted DDL (gh-5515).

  • Fixed a bug where memtx MVCC crashed if an index was created in the transaction thread (gh-6137).

  • Fixed a MVCC segmentation fault that arose when updating the entire space concurrently (gh-5892).

  • Fixed a bug with failed assertion after a stress update of the same key (gh-6193).

  • Fixed a crash where box.snapshot could be called during an incomplete transaction (gh-6229).

  • Fixed console client connection failure in case of request timeout (gh-6249).

  • Added a missing broadcast to net.box.future:discard() so that now fibers waiting for a request result wake up when the request is discarded (gh-6250).

  • box.info.uuid, box.info.cluster.uuid, and tostring(decimal) with any decimal number in Lua could sometimes return garbage if there were __gc handlers in the user’s code (gh-6259).

  • Fixed an error message that appeared in a particular case during MVCC operation (gh-6247).

  • Fixed a repeatable read violation after delete (gh-6206).

  • Fixed a bug where the MVCC engine didn’t track the select{} hash (gh-6040).

  • Fixed a crash in MVCC after a drop of space with several indexes (gh-6274).

  • Fixed a bug where the GC could leave tuples in secondary indexes (gh-6234).

  • Disallow yields after DDL operations in MVCC mode. It fixes a crash that took place when several transactions referred to system spaces (gh-5998).

  • Fixed a bug in MVCC that happened on rollback after a DDL operation (gh-5998).

  • Fixed a bug where rollback resulted in unserializable behavior (gh-6325).

Vinyl

  • Fixed possible keys divergence during secondary index build, which might lead to missing tuples (gh-6045).
  • Fixed the race between Vinyl garbage collection and compaction that resulted in a broken vylog and recovery failure (gh-5436).

Replication

  • Fixed the use after free in the relay thread when using elections (gh-6031).
  • Fixed a possible crash when a synchronous transaction was followed by an asynchronous transaction right when its confirmation was being written (gh-6057).
  • Fixed an error where a replica, while attempting to subscribe to a foreign cluster with a different replicaset UUID, didn’t notice it is impossible and instead became stuck in an infinite retry loop printing a TOO_EARLY_SUBSCRIBE error (gh-6094).
  • Fixed an error where a replica, while attempting to join a cluster with exclusively read-only replicas available, just booted its own replicaset, instead of failing or retrying. Now it fails with an error about the other nodes being read-only so they can’t register the new replica (gh-5613).
  • Fixed error reporting associated with transactions received from remote instances via replication. Any error raised while such a transaction was being applied was always reported as Failed to write to disk regardless of what really happened. Now the correct error is shown. For example, Out of memory, or Transaction has been aborted by conflict, and so on (gh-6027).
  • Fixed replication occasionally stopping with ER_INVALID_MSGPACK when the replica is under high load (gh-4040).
  • Fixed a cluster sometimes being unable to bootstrap if it contains nodes with election_mode set to manual or voter (gh-6018).
  • Fixed a possible crash when box.ctl.promote() was called in a cluster with more than three instances. The crash happened in the debug build. In the release build, it could lead to undefined behaviour. It was likely to happen if a new node was added shortly before the promotion (gh-5430).
  • Fixed a rare error appearing when MVCC (box.cfg.memtx_use_mvcc_engine) was enabled and more than one replica joined the cluster. The join could fail with the error "ER_TUPLE_FOUND: Duplicate key exists in unique index 'primary' in space '_cluster'". The same could happen at the bootstrap of a cluster having more than three nodes (gh-5601).

Raft

  • Fixed a rare crash with leader election enabled (any mode except off), which could happen if a leader resigned from its role while another node was writing something elections-related to WAL. The crash was in the debug build, and in the release build it would lead to undefined behaviour (gh-6129).
  • Fixed an error where a new replica in a Raft cluster tried to join from a follower instead of a leader and failed with the error ER_READONLY (gh-6127).

LuaJIT

  • Fixed optimization for single-char strings in the IR_BUFPUT assembly routine.
  • Fixed slots alignment in the lj-stack command output when LJ_GC64 is enabled (gh-5876).
  • Fixed dummy frame unwinding in the lj-stack command.
  • Fixed detection of inconsistent renames even in the presence of sunk values (gh-4252, gh-5049, gh-5118).
  • Fixed the VM register allocation order provided by LuaJIT frontend in case of BC_ISGE and BC_ISGT (gh-6227).

Lua

  • When an error occurs during encoding call results, the auxiliary lightuserdata value is not removed from the main Lua coroutine stack. Before the fix, it led to undefined behaviour during the next usage of this Lua coroutine (gh-4617).
  • Fixed a Lua C API misuse when the error is raised during call results encoding in an unprotected coroutine and expected to be caught in a different, protected coroutine (gh-6248).

Triggers

  • Fixed a possible crash in case trigger removes itself. Fixed a possible crash in case someone destroys a trigger when it yields (gh-6266).

SQL

  • User-defined functions can now return a VARBINARY result to SQL (gh-6024).
  • Fixed assert when a DOUBLE value greater than -1.0 and less than 0.0 is cast to INTEGER and UNSIGNED (gh-6225).
  • Removed spontaneous conversion from INTEGER to DOUBLE in a field of the NUMBER type (gh-5335).
  • All arithmetic operations can now accept numeric values only (gh-5756).

MVCC

  • Fixed MVCC interaction with ephemeral spaces: TX manager now ignores them (gh-6095).
  • Fixed loss of tuples after a conflict exception (gh-6132).
  • Fixed a segfault during update/delete of the same tuple (gh-6021).

Tarantool 2.8.1

Дата выхода: 2021-04-21.

Общие сведения

2.8.1 — бета-версия, входящая в серию 2.8.

Эта версия содержит 28 новых функций и 31 исправление по сравнению с версией 2.7.2. Возможны ошибки в менее распространенных функциях. Если вы обнаружили проблему, сообщите о ней на GitHub.

Важные изменения:

Совместимость

Любая версия Tarantool 2.x обратно совместима с версиями Tarantool 1.10.x. Это касается структур двоичных данных, клиент-серверного протокола и протокола репликации.

Чтобы получить доступ ко всем новым функциям серии 2.x, обновите Tarantool с помощью box.schema.upgrade().

Обновления функциональности

Основные функции (Core)

  • При определении индексируемых полей теперь можно использовать параметр exclude_null. Тогда в индексе не будут сохраняться кортежи, соответствующее поле которых имеет значение null (gh-4480).

    Например, в индекс, созданный методом s:create_index('sk', {parts={{2, 'number', exclude_null=true}}}), не войдут кортежи {1, null} и {2, null}, но могут войти кортежи {null, 1} и {1, 1}.

  • В box.cfg{} добавлен параметр slab_alloc_granularity, позволяющий настроить гранулярность выделения памяти для аллокатора small. Значение slab_alloc_granularity должно быть степенью двойки, но не менее 4 (gh-5518).

  • В предыдущих версиях триггеры Lua on_shutdown запускались последовательно. Теперь каждый триггер запускается в отдельном файбере. По умолчанию Tarantool в течение 3 секунд ожидает, когда завершится обработка триггеров. Пользователь может изменить этот временной промежуток с помощью новой функции box.ctl.set_on_shutdown_timeout.

    Когда время истечёт, Tarantool немедленно завершит работу, не дожидаясь окончания обработки оставшихся триггеров.

  • Tarantool module developers can now register functions to call when Tarantool stops with the new on_shutdown API, (gh-5723). Read more: on_shutdown.

  • Введена очередь журнала упреждающей записи (WAL). Размер очереди в байтах определяется новым параметром конфигурации wal_queue_max_size. Его значение по умолчанию — 16 МБ. Параметр позволяет ограничить объем транзакций, которые реплика заносит в WAL. Проверка ограничения происходит каждый раз, когда транзакция с мастера заносится в WAL на реплике. Как только транзакция будет успешно записана, ее место в очереди освободится (gh-5536).

  • Информацию о состоянии синхронной репликации теперь можно получить через интерфейс box.info.synchro (gh-5191).

  • Теперь Tarantool позволяет запускать несколько потоков (threads) IPROTO. Это полезно в ситуациях, когда единственный поток IPROTO становится узким местом производительности (gh-5645).

  • При операции обновления кортежей (update) пропуск полей не поддерживается. Пропущенные поля теперь заменяются нулевыми значениями (gh-3378).

  • Новый модуль box.lib позволяет загружать и выполнять хранимые процедуры на языке C на узлах, доступных только для чтения (gh-4642).

  • Configuration options in box.cfg can now be defined with environment variables (gh-5602).

    Применяются параметры конфигурации из следующих источников в порядке приоритета:

    • box.cfg{};
    • переменные окружения;
    • параметры tarantoolctl;
    • значения по умолчанию.

Репликация

  • Добавлена функция box.ctl.promote(), введены ручные выборы лидера. Чтобы их включить, укажите параметр election_mode='manual' (gh-3055).

    Экземпляр, находящийся в ручном (manual) режиме выборов, большую часть времени имеет роль voter, но при вызове box.ctl.promote() может начать выборы и стать лидером. Если election_mode ~= 'manual', метод box.ctl.promote() делает то же, что устаревший метод box.ctl.clear_synchro_queue().

LuaJIT

  • Отчет профилировщика памяти LuaJIT стал удобнее для чтения (gh-5811). Теперь проще понять, в какой строке кода происходит событие. Пользователь видит имя исходного файла и строку, где выделяется память, а также количество событий и статистику памяти в байтах. Номер строки с определением функции не отображается.

    Критическое изменение: информация о строке, в которой определяется функция, теперь сохраняется в поле linedefined таблицы символов. Поле name теперь называется source в соответствии с Lua API для отладки.

  • Ряд изменений в парсере профилировщика памяти:

    • Теперь отчет парсера включает информацию об изменениях в состоянии динамической памяти, возникших за период работы профилировщика (gh-5812).
    • Чтобы посмотреть только эти изменения, используйте параметр --leak-only.
    • Новый встроенный модуль memprof.process производит постобработку и агрегацию событий, связанных с выделением памяти.

    Чтобы запустить профилировщик памяти, используйте следующую команду:

    tarantool -e 'require("memprof")(arg)' - --leak-only /tmp/memprof.bin

Инструменты

  • Реализованы новые инструменты для анализа инцидентов и сбора соответствующих артефактов (gh-5569).

Сборка

  • Инфраструктура сборки Tarantool теперь требует использования CMake версии 3.2 или более поздней.
  • Доступны бинарные пакеты для Fedora 33 (gh-5502).
  • Начиная с этой версии, бинарные пакеты для CentOS 6 и Debian Jessie не публикуются.
  • Среди зависимостей для RPM- и DEB-пакетов больше нет autotools (следствие gh-4968).
  • Регулярное тестирование на MacOs 10.13 больше не проводится. Поддержка Tarantool для этой версии MacOS прекращена.
  • Встроенный модуль zstd обновлён с версии 1.3.3 до версии 1.4.8 (в рамках gh-5502).
  • Библиотека libcurl, входящая в сборку, теперь поддерживает протоколы SMTP и SMTPS (gh-4559).
  • Файлы заголовков библиотеки libcurl, входящей в сборку, устанавливаются в системный каталог ${PREFIX}/include/tarantool (gh-4559).

Тестирование

  • CI/CD Tarantool теперь проводится посредством GitHub Actions (gh-5662).
  • Тестирование с помощью Jepsen на отдельных узлах теперь происходит каждый раз, когда выполняется push новых тегов, а также по cron каждые 3 часа (gh-5736).
  • Фаззинг-тесты запускаются каждый раз, когда выполняется push (gh-1809).
  • Реализовано независимое окружение для тестирования LuaJIT. Система сборки LuaJIT частично портирована на CMake. Инструменты для тестирования теперь находятся в репозитории tarantool/luajit (gh-4862, gh-5470).
  • Теперь в инфраструктуре тестирования по умолчанию установлен Python 3 (gh-5652).

Исправленные ошибки

Основные функции (Core)

  • Параметры индексируемых полей больше не пропускаются в случаях, когда тип поля не определён (gh-5674).
  • Функция lbox_ctl_is_recovery_finished() больше не возвращает значение true в случае, если процесс восстановления ещё не завершён.
  • Устранена ошибка повреждения памяти в модуле net.box. До этого исправления область памяти, занятая структурой error, освобождалась преждевременно, поскольку методы ffi.gc и ffi.cast вызывались не в том порядке.
  • При передаче данных на реплику, которая присоединяется к кластеру или синхронизируется с мастером, больше не может истечь время ожидания (gh-5762).
  • Устранена проблема, из-за которой модуль net.box получал схему индекса, в которой не содержится значение path (gh-5451).
  • Раньше интенсивное использование модулей uri и uuid при уровне логирования DEBUG приводило к сбоям, а результаты выполнения функций, входящих в эти модули, могли быть повреждены. Теперь эта проблема решена. Та же проблема устранена для случаев, когда модули uri и uuid используются в callback-функциях, передаваемых в метод ffi.gc(), а также для некоторых функций, входящих в модули fio, box.tuple и iconv (gh-5632).
  • Новый параметр wal_cleanup_delay предотвращает преждевременное удаление файлов *.xlog, необходимых репликам. Ранее при удалении возникала ошибка XlogGapError (gh-5806).
  • Когда на мастере есть синхронные спейсы, во время стадии join на реплике больше не возникают ошибки Unknown request type 40 (gh-5566).
  • Исправлена ошибка при перезагрузке скомпилированного модуля, возникавшая, если обновлённый модуль не содержал части функций, которые были в прежнем коде. Раньше событие запускало процедуру восстановления удалённых функций. Однако вместо того, чтобы восстанавливать каждую функцию по отдельности, Tarantool ошибочно обрабатывал единственную запись, что приводило к сбою при вызове любой из этих функций (gh-5968).
  • Решена проблема фантомных чтений: теперь механизм MVCC движка memtx отслеживает интервалы чтения (gh-5628).
  • Функция space:count(), используемая с механизмом MVCC движка memtx, больше не выдаёт ошибочный результат (gh-5972).
  • Исправлена проблема «грязного чтения» после перезапуска, возникающая при использовании механизма MVCC и синхронной репликации (gh-5973).

Репликация

  • Устранена проблема, из-за которой applier не обрабатывал сообщения CONFIRM или ROLLBACK от мастера и не давал ответа реплике.
  • Устранена проблема, из-за которой некоторые кортежи не отправлялись с мастера на анонимную реплику, отставшую от него и пытающуюся зарегистрироваться в кластере.
  • Исправлена ошибка, из-за которой синхронная транзакция подтверждалась и отображалась на реплике, а после перезагрузки исчезала вновь. Чаще всего это происходило в спейсах memtx при включённом механизме memtx_use_mvcc_engine (gh-5213).
  • Устранены проблемы с восстановлением отмененной синхронной транзакции, состоящей из нескольких инструкций. Если такая транзакция относилась к асинхронным спейсам, она могла быть частично применена или восстановлена с ошибками (gh-5874).
  • Исправлена ошибка синхронной репликации, из-за которой при подключении достаточно старого экземпляра отменённые транзакции могли быть применены вновь (gh-5445).

Модуль swim

  • Исправлена ошибка, из-за которой метод <swim_instance>:broadcast() не работал на нелокальных адресах и постоянно заносил в журнал сообщения об ошибке «Permission denied». Если работа экземпляра прекращалась, метод мог вернуть ненулевой код завершения даже при отсутствии ошибок в скрипте, а затем снова начать массово логировать сообщения о той же ошибке (gh-5864).
  • Устранён сбой, возникавший при вызове swim:member_by_uuid() с аргументом nil/box.NULL или без аргументов (gh-5951).
  • Устранён сбой, возникавший при попытке передать объект неподходящего типа в метод __serialize реплики-участника swim в Lua (gh-5952).

LuaJIT

  • Изменение размера стека Lua больше не приводит к ошибочному поведению профилировщика памяти (gh-5842).
  • Исправлена ошибка, из-за которой значение gc_cdatanum в метриках платформы LuaJIT уменьшалось на две единицы. Ошибка возникала в случаях, когда финализатор был назначен для объекта типа GCсdata (gh-5820).

Lua

  • Устранена проблема с параметром -e. Ранее, если в качестве стандартного устройства ввода был установлен терминал, команда tarantool запускала интерактивный режим. Теперь команда tarantool -e "print('Hello')") просто выводит слово Hello и завершает работу (gh-5040).
  • Устранена утечка кортежа, возникавшая при ошибке сериализации ключа во время выполнения key_def:compare_with_key(кортеж, ключ) (gh-5388).

SQL

  • Пользовательские C- или Lua-функции теперь получают ровно те же строки, что в них передаются посредством SQL. Различия могли возникать, если строка содержала \\0 (gh-5938).
  • Инструкции SQL SELECT и SQL UPDATE в отношении полей UUID и DECIMAL больше не вызывают ошибок сегментации (gh-5011, gh-5704, gh-5913).
  • Устранена проблема, из-за которой инструкции SELECT и GROUP BY, выполняемые в рамках одной транзакции, приводили к неверным результатам. Проблема возникала, когда одно из обрабатываемых значений имело тип VARBINARY, а обращение к нему не происходило с помощью инструкции SELECT напрямую (gh-5890).

Сборка

  • Устранена проблема сборки на FreeBSD, связанная с неполным определением типа struct sockaddr (gh-5748).

  • Уже скачанные зависимости статической сборки не будут скачиваться повторно (gh-5761).

  • В ходе восстановления с помощью параметра force_recovery теперь удаляются файлы .vylog, созданные позднее, чем снимок данных. Благодаря этому экземпляр может восстанавливаться после инцидентов, возникающих во время сохранения контрольной точки (gh-5823).

  • Устранены проблемы с конфигурацией libcurl, возникавшие, когда для сборки Tarantool использовалась команда cmake3, а в переменной PATH отсутствовал путь к cmake (gh-5955).

    Это исправление влияет на сборку Tarantool со встроенной библиотекой libcurl (стандартный тип сборки).

Tarantool 2.7.3

Released on 2021-08-19.

Overview

2.7.3 is the second stable version of the 2.7 release series. It introduces 6 improvements and resolves 49 bugs since version 2.7.2.

The “stable” label means that we have all planned features implemented and we see no high-impact issues. However, if you encounter an issue, feel free to report it on GitHub.

Compatibility

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Some changes are labeled as [Breaking change]. It means that the old behavior was considered error-prone and therefore changed to protect users from unintended mistakes. However, there is a small probability that someone can rely on the old behavior, and this label is to bring attention to the things that have been changed.

Functionality added or changed

Core

  • The information about the state of synchronous replication is now available via the box.info.synchro interface (gh-5191).

LuaJIT

  • Introduced support for LJ_DUALNUM mode in luajit-gdb.py (gh-6224).

Lua

  • Introduced the new method table.equals. It compares two tables by value with respect to the __eq metamethod.

SQL

  • Descriptions of type mismatch error and inconsistent type error have become more informative (gh-6176).

  • Removed explicit cast from BOOLEAN to numeric types and vice versa (gh-4770).

    For example, CAST(FALSE AS INTEGER) was 0 in version 2.8. Now it causes an error.

  • Removed explicit cast from VARBINARY to numeric types and vice versa (gh-4772, gh-5852).

  • Fixed a bug where a string that is not NULL-terminated could not be cast to BOOLEAN, even if the conversion would be successful according to the rules.

Build

  • Fedora 34 builds are now supported (gh-6074).
  • Fedora 28 and 29 builds are no longer supported.

Bugs fixed

Core

  • [Breaking change] fiber.wakeup() in Lua and fiber_wakeup() in C became NOP on the currently running fiber. Previously they allowed “ignoring” the next yield or sleep, which resulted in unexpected erroneous wake-ups. Calling these functions right before fiber.create() in Lua or fiber_start() in C could lead to a crash (in debug build) or undefined behaviour (in release build) (gh-6043).

    There was a single use case for the previous behaviour: rescheduling in the same event loop iteration, which is not the same as fiber.sleep(0) in Lua and fiber_sleep(0) in C. It could be done in the following way:

    in C:

    fiber_wakeup(fiber_self());
fiber_yield();

    and in Lua:

    fiber.self():wakeup()
fiber.yield()

    To get the same effect in C, one can now use fiber_reschedule(). In Lua, it is now impossible to reschedule the current fiber directly in the same event loop iteration. One can reschedule self through a second fiber, but it is strongly discouraged:

    -- do not use this code
local self = fiber.self()
fiber.new(function() self:wakeup() end)
fiber.sleep(0)

  • Fixed memory leak on box.on_commit() and box.on_rollback() (gh-6025).

  • fiber_join() now checks if the argument is a joinable fiber. The absence of this check could lead to unpredictable results. Note that the change affects the C level only; in the Lua interface, fiber:join() protection is already enabled.

  • Now Tarantool yields when it scans .xlog files for the latest applied vclock and finds the right place to start recovering from. It means that the instance becomes responsive right after the box.cfg call even if an empty .xlog was not created on the previous exit.

    This fix also prevents the relay from timing out when a freshly subscribed replica needs rows from the end of a relatively long (hundreds of MBs) .xlog file (gh-5979).

  • The counter in N rows processed log messages no longer resets on each newly recovered xlog.

  • Fixed invalid results of the json module’s encode function when it was used from the Lua garbage collector. For example, this could happen in functions used as ffi.gc() (gh-6050).

  • Simultaneously updating a key in different transactions does not longer result in a MVCC crash (gh-6131).

  • Fixed a bug where memtx MVCC crashed during reading uncommitted DDL (gh-5515).

  • Fixed a bug where memtx MVCC crashed if an index was created in the transaction thread (gh-6137).

  • Fixed a MVCC segmentation fault that arose when updating the entire space concurrently (gh-5892).

  • Fixed crash in case of reloading a compiled module when the new module lacks some functions present in the former code. In turn, this event triggers a fallback procedure where we restore old functions, but instead of restoring each function, we process a sole entry only, leading to the crash later when these restored functions are called (gh-5968).

  • Fixed a bug with failed assertion after a stress update of the same key (gh-6193).

  • Fixed a crash where box.snapshot could be called during an incomplete transaction (gh-6229).

  • Fixed console client connection failure in case of request timeout (gh-6249).

  • Added a missing broadcast to net.box.future:discard() so that now fibers waiting for a request result wake up when the request is discarded (gh-6250).

  • box.info.uuid, box.info.cluster.uuid, and tostring(decimal) with any decimal number in Lua could sometimes return garbage if there were __gc handlers in the user’s code (gh-6259).

  • Fixed an error message that appeared in a particular case during MVCC operation (gh-6247).

  • Fixed a repeatable read violation after delete (:gh-6206).

  • Fixed a bug where the MVCC engine didn’t track the select{} hash (gh-6040).

  • Fixed a crash in MVCC after a drop of space with several indexes (gh-6274).

  • Fixed a bug where the GC could leave tuples in secondary indexes (gh-6234).

  • Disallow yields after DDL operations in MVCC mode. It fixes a crash that took place when several transactions referred to system spaces (gh-5998).

  • Fixed a bug in MVCC that happened on rollback after a DDL operation (gh-5998).

  • Fixed a bug where rollback resulted in unserializable behavior (gh-6325).

Vinyl

  • Fixed possible keys divergence during secondary index build, which might lead to missing tuples (gh-6045).
  • Fixed the race between Vinyl garbage collection and compaction that resulted in a broken vylog and recovery failure (gh-5436).

Replication

  • Fixed the use after free in the relay thread when using elections (gh-6031).
  • Fixed a possible crash when a synchronous transaction was followed by an asynchronous transaction right when its confirmation was being written (gh-6057).
  • Fixed an error where a replica, while attempting to subscribe to a foreign cluster with a different replicaset UUID, didn’t notice it is impossible and instead became stuck in an infinite retry loop printing a TOO_EARLY_SUBSCRIBE error (gh-6094).
  • Fixed an error where a replica, while attempting to join a cluster with exclusively read-only replicas available, just booted its own replicaset, instead of failing or retrying. Now it fails with an error about the other nodes being read-only so they can’t register the new replica (gh-5613).
  • Fixed error reporting associated with transactions received from remote instances via replication. Any error raised while such a transaction was being applied was always reported as Failed to write to disk regardless of what really happened. Now the correct error is shown. For example, Out of memory, or Transaction has been aborted by conflict, and so on (gh-6027).
  • Fixed replication occasionally stopping with ER_INVALID_MSGPACK when the replica is under high load (gh-4040).
  • Fixed a cluster sometimes being unable to bootstrap if it contains nodes with election_mode set to manual or voter (gh-6018).
  • Fixed a possible crash when box.ctl.promote() was called in a cluster with more than three instances. The crash happened in the debug build. In the release build, it could lead to undefined behaviour. It was likely to happen if a new node was added shortly before the promotion (gh-5430).
  • Fixed a rare error appearing when MVCC (box.cfg.memtx_use_mvcc_engine) was enabled and more than one replica joined the cluster. The join could fail with the error "ER_TUPLE_FOUND: Duplicate key exists in unique index 'primary' in space '_cluster'". The same could happen at the bootstrap of a cluster having more than three nodes (gh-5601).

Raft

  • Fixed a rare crash with leader election enabled (any mode except off), which could happen if a leader resigned from its role while another node was writing something elections-related to WAL. The crash was in the debug build, and in the release build it would lead to undefined behaviour (gh-6129).
  • Fixed an error where a new replica in a Raft cluster tried to join from a follower instead of a leader and failed with the error ER_READONLY (gh-6127).

LuaJIT

  • Fixed optimization for single-char strings in the IR_BUFPUT assembly routine.
  • Fixed slots alignment in the lj-stack command output when LJ_GC64 is enabled (gh-5876).
  • Fixed dummy frame unwinding in the lj-stack command.
  • Fixed detection of inconsistent renames even in the presence of sunk values (gh-4252, gh-5049, gh-5118).
  • Fixed the VM register allocation order provided by LuaJIT frontend in case of BC_ISGE and BC_ISGT (gh-6227).

Lua

  • When an error occurs during encoding call results, the auxiliary lightuserdata value is not removed from the main Lua coroutine stack. Before the fix, it led to undefined behaviour during the next usage of this Lua coroutine (gh-4617).
  • Fixed a Lua C API misuse when the error is raised during call results encoding in an unprotected coroutine and expected to be caught in a different, protected coroutine (gh-6248).

Triggers

  • Fixed a possible crash in case trigger removes itself. Fixed a possible crash in case someone destroys a trigger when it yields (gh-6266).

SQL

  • User-defined functions can now return a VARBINARY result to SQL (gh-6024).
  • Fixed assert when a DOUBLE value greater than -1.0 and less than 0.0 is cast to INTEGER and UNSIGNED (gh-6225).
  • Removed spontaneous conversion from INTEGER to DOUBLE in a field of the NUMBER type (:gh-5335).
  • All arithmetic operations can now accept numeric values only (gh-5756).

MVCC

  • Fixed MVCC interaction with ephemeral spaces: TX manager now ignores them (gh-6095).
  • Fixed loss of tuples after a conflict exception (gh-6132).
  • Fixed a segfault during update/delete of the same tuple (gh-6021).

Tarantool 2.7.2

Released on 2021-04-21.

Общие сведения

2.7.2 is the first stable version of the 2.7 release series. It introduces 15 improvements and resolves 30 bugs since version 2.7.1.

The “stable” label means that we have all planned features implemented and we see no high-impact issues. However, if you encounter an issue, feel free to report it on GitHub.

Совместимость

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Изменения или добавления функциональности

Core

  • Introduced the concept of WAL queue and the new configuration option wal_queue_max_size, measured in bytes. The default value is 16 Mb. The option helps limit the pace at which replica submits new transactions to the WAL. The limit is checked every time a transaction from the master is submitted to the replica’s WAL. The space taken by the transaction is considered empty once it’s successfully written (gh-5536).

Репликация

  • Introduced the box.ctl.promote() function and the concept of manual elections (enabled with election_mode='manual') (gh-3055).

    Once the instance is in the manual election mode, it acts like a voter most of the time, but may trigger elections and become a leader when box.ctl.promote() is called. When election_mode ~= 'manual', box.ctl.promote() replaces box.ctl.clear_synchro_queue(), which is now deprecated.

Build

  • Tarantool build infrastructure now requires CMake version 3.1 or later.
  • Binary packages for Fedora 33 are now available (gh-5502) .
  • Binary packages for CentOS 6 and Debian Jessie won’t be published since this version.
  • RPM and DEB packages no longer have the autotools dependency (follows up gh-4968).
  • Regular testing on MacOS 10.13 has been disabled, effectively stopping the support of this version.
  • The built-in zstd is upgraded from v1.3.3 to v1.4.8 (part of gh-5502).
  • SMTP and SMTPS protocols are now enabled in the bundled libcurl (gh-4559).
  • The libcurl headers are now shipped to system path ${PREFIX}/include/tarantool when libcurl is included as a bundled library or in a static build (gh-4559).

Тестирование

  • Tarantool CI/CD has migrated to GitHub Actions (gh-5662).
  • Single node Jepsen testing now runs on per-push basis (gh-5736).
  • A self-sufficient LuaJIT testing environment has been implemented. As a result, LuaJIT build system is now partially ported to CMake and all testing machinery is enclosed within the tarantool/luajit repository (gh-4862, gh-5470).
  • Python 3 is now the default in the test infrastructure (gh-5652).

Исправленные ошибки

Core

  • The index part options are no longer skipped when the field type is not specified (gh-5674).
  • The lbox_ctl_is_recovery_finished() function no longer returns true when recovery is still in progress.
  • A memory corruption bug has been fixed in netbox. The memory of a struct error which is still used will no longer be freed prematurely because of the wrong order of ffi.gc and ffi.cast calls.
  • Relay can no longer time out while a replica is joining or syncing with the master. (gh-5762).
  • An issue with missing «path» value of index schema fetched by netbox has been fixed (gh-5451).
  • Extensive usage of uri and uuid modules with debug log level no longer leads to crashes or corrupted results of the functions from these modules. Same problem is resolved for using these modules from the callbacks passed to ffi.gc(), and for some functions from the modules fio, box.tuple, and iconv (gh-5632).
  • The new wal_cleanup_delay option can prevent early cleanup of *.xlog files, needed by replicas. Such cleanup used to result in a XlogGapError (gh-5806).
  • Appliers will no longer cause errors with Unknown request type 40 during a final join when the master has synchronous spaces (gh-5566).
  • Added memtx MVCC tracking of read gaps which fixes the problem of phantom reads (gh-5628).
  • Fixed the wrong result of using space:count() with memtx MVCC (gh-5972).
  • Fixed the dirty read after restart while using MVCC with synchronous replication (gh-5973).

Репликация

  • Fixed an issue with an applier hanging on a replica after failing to process a CONFIRM or ROLLBACK message coming from a master.
  • Fixed the issue where master did not send some rows to an anonymous replica which had fallen behind and was trying to register.
  • Fixed the bug when a synchronous transaction could be confirmed and visible on a replica, but then not confirmed or invisible again after restart. It was more likely to happen on memtx spaces with memtx_use_mvcc_engine enabled (gh-5213).
  • Fixed the recovery of a rolled back multi-statement synchronous transaction which could lead to the transaction being applied partially, and to recovery errors. It happened in case the transaction worked with non-sync spaces (gh-5874).
  • Fixed a bug in synchronous replication when rolled back transactions could reappear after reconnecting a sufficiently old instance (gh-5445).

Module swim

  • Fixed an issue where <swim_instance>:broadcast() did not work on non-local addresses and spammed «Permission denied» errors to the log. After instance termination it could return a non-0 exit code even if there were no errors in the script, and then spam the same error again (gh-5864).
  • Fixed the crash on attempts to call swim:member_by_uuid() with no arguments or with nil/box.NULL (gh-5951).
  • Fixed the crash on attempts to pass an object of a wrong type to __serialize method of a swim member in Lua (gh-5952).

LuaJIT

  • Lua stack resizing no longer results in a wrong behaviour of the memory profiler (gh-5842).
  • Fixed a double gc_cdatanum decrementing in LuaJIT platform metrics which occurred when a finalizer was set for a GCсdata object (gh-5820).

Lua

  • Fixed the -e option, when tarantool used to enter the interactive mode when stdin is a TTY. Now, tarantool -e 'print"Hello"' doesn’t enter the interactive mode, but just prints «Hello» and exits (gh-5040).
  • Fixed a leak of a tuple object in key_def:compare_with_key(tuple, key), which had occurred when the serialization of the key failed (gh-5388).

SQL

  • The string received by a user-defined C or Lua function will no longer be different from the string passed to the function. This could happen when the string passed from SQL had contained \\0 (gh-5938).
  • SQL SELECT or SQL UPDATE on UUID or DECIMAL field will not cause a SEGMENTATION FAULT anymore (gh-5011, gh-5704, gh-5913).
  • Fixed an issue with wrong results of SELECT with GROUP BY which occurred when one of the selected values was VARBINARY and not directly obtained from the space (gh-5890).

Build

  • Fix building on FreeBSD (incomplete definition of type struct sockaddr) (gh-5748).

  • The already downloaded static build dependencies will not be fetched repeatedly (gh-5761).

  • Recovering with force_recovery option now deletes vylog files which are newer than the snapshot. It helps an instance recover after incidents during a checkpoint (gh-5823).

  • Fixed the libcurl configuring when Tarantool itself has been configured with cmake3 command and there was no cmake command in the PATH (gh-5955).

    This affects building Tarantool from sources with bundled libcurl (it is the default mode).

Tarantool 2.7.1

Release: v. 2.7.1 Date: 2020-12-30 Tag: 2.7.1-0-g3ac498c9f

Общие сведения

2.7.1 is the beta version of the 2.7 release series.

This release introduces 12 new features and resolves 21 bugs since the 2.6.1 version. There can be bugs in less common areas. If you find any, feel free to report an issue on GitHub.

Notable changes are:

Совместимость

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Изменения или добавления функциональности

Core

  • Now it is allowed to define an index without extra braces when there is only one part: parts = {field1, type1, ...} (gh-2866). Read more in the note about index parts declaration.
  • Bitset index now supports the varbinary type (gh-5392).
  • Index-related options now can’t be specified in their definition due to a more pedantic key-parts verification (gh-5473).
  • A warning is now logged when schema version is older than last available schema version (gh-4574).
  • UUID values created via uuid Lua module (require('uuid')) can now be compared using the comparison operators like <, >=, and others (gh-5511).
  • The new box.ctl.is_recovery_finished() function allows user to determine whether memtx recovery is finished.
  • The force_recovery option now ignores errors during snapshot recovery (gh-5422).
  • Feedback daemon now reports box.stat().*.total, box.stat.net().*.total, and box.stat.net().*.current together with the time of report generation. The added fields reside in feedback.stats.box, feedback.stats.net, and feedback.stats.time (gh-5589).

LuaJIT

Lua

  • Show JSON tokens themselves instead of token names T_* in the JSON decoder error messages (gh-4339).
  • Show a decoding context in the JSON decoder error messages (gh-4339).

SQL

Репликация

  • It is now possible to specify synchro quorum as a function of a number N of registered replicas instead of a const number, for example:

    box.cfg{replication_synchro_quorum = "N/2 + 1"}

    Only the non-anonymous bootstrapped replicas amount to N. The expression should respect synchro guarantees: at least 50% of the cluster size + 1. The expression value is re-evaluated automatically inside of Tarantool when new replicas appear or old ones are removed (gh-5446).

Build

  • Deploy packages for Fedora 32 (gh-4966).
  • Deploy packages for Debian Bullseye (gh-5638).

Разное

  • If Tarantool crashes, it will now send a crash dump report to the feedback server. This report contains some fields from uname output, build information, crash reason, and a stack trace. You can disable crash reporting with box.cfg{feedback_crashinfo = false} (gh-5261).

Исправленные ошибки

Core

  • fiber.cond:wait() now correctly throws an error when a fiber is cancelled, instead of ignoring the timeout and returning without any signs of an error (gh-5013).
  • Fixed a memory corruption issue, which was most visible on macOS, but could affect any system (gh-5312).
  • A dynamic module now gets correctly unloaded from memory in case of an attempt to load a non-existing function from it (gh-5475).
  • A swim:quit() call now can’t result in a crash (gh-4570).
  • Snapshot recovery with no JSONPath or multikey indices involved now has normal performance (gh-4774).

Репликация

  • A false-positive “too long WAL write” message no longer appears for synchronous transactions (gh-5139).
  • A box.ctl.wait_rw() call could return when the instance was not in fact writable due to having foreign synchronous transactions. As a result, there was no proper way to wait until the automatically elected leader would become writable. Now box.ctl.wait_rw() works correctly (gh-5440).
  • Fixed a couple of crashes on various tweaks of election mode (gh-5506).
  • Now box.ctl.clear_synchro_queue tries to commit everything that is present on the node. In order to do so it waits for other instances to replicate the data for replication_synchro_quorum seconds. In case timeout passes and quorum wasn’t reached, nothing is rolled back (gh-5435).

SQL

  • Data changes in read-only mode are now forbidden (gh-5231).
  • Query execution now does not occasionally raise an unrelated error “Space ‘0’ does not exist” (gh-5592).
  • Coinciding names of temporary files (used to store data during execution) having two instances running on the same machine no longer cause a segfault (gh-5537).
  • The return value of ifnull() built-in function is now of a correct type.
  • SQL calling Lua functions with box calls inside can no longer result in a memory corruption (gh-5427).

LuaJIT

  • Dispatching __call metamethod no longer causes address clashing (gh-4518, gh-4649).
  • Fixed a false positive panic when yielding in debug hook (gh-5649).

Lua

  • An attempt to use a net.box connection which is not established yet now results in a correctly reported error (gh-4787).
  • Fixed a NULL dereference on error paths in merger which usually happened on a ‘wrong’ key_def (gh-5450).
  • Calling key_def.compare_with_key() with an invalid key no longer causes a segfault (gh-5307).
  • Fixed a hang which occured when tarantool ran a user script with the -e option and this script exited with an error (like with tarantool -e 'assert(false)') (gh-4983).

Memtx

  • The on_schema_init triggers now can’t cause duplicates in primary key (gh-5304).

Tarantool 2.6.3

Released on 2021-04-21.

Общие сведения

2.6.3 is the second stable version of the 2.6 release series. It introduces 15 improvements and resolves 28 bugs since version 2.6.2.

The «stable» label means that we have all planned features implemented and we see no high-impact issues. However, if you encounter an issue, feel free to report it on GitHub.

Совместимость

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Изменения или добавления функциональности

Core

  • Introduced the concept of WAL queue and the new configuration option wal_queue_max_size, measured in bytes. The default value is 16 Mb. The option helps limit the pace at which replica submits new transactions to the WAL. The limit is checked every time a transaction from the master is submitted to the replica’s WAL. The space taken by the transaction is considered empty once it’s successfully written (gh-5536).

Репликация

  • Introduced the box.ctl.promote() function and the concept of manual elections (enabled with election_mode='manual') (gh-3055).

    Once the instance is in the manual election mode, it acts like a voter most of the time, but may trigger elections and become a leader when box.ctl.promote() is called. When election_mode ~= 'manual', box.ctl.promote() replaces box.ctl.clear_synchro_queue(), which is now deprecated.

Build

  • Tarantool build infrastructure now requires CMake version 3.1 or later.
  • Binary packages for Fedora 33 are now available (gh-5502) .
  • Binary packages for CentOS 6 and Debian Jessie won’t be published since this version.
  • RPM and DEB packages no longer have the autotools dependency (follows up gh-4968).
  • Regular testing on MacOS 10.13 has been disabled, effectively stopping the support of this version.
  • The built-in zstd is upgraded from v1.3.3 to v1.4.8 (part of gh-5502).
  • SMTP and SMTPS protocols are now enabled in the bundled libcurl (gh-4559).
  • The libcurl headers are now shipped to system path ${PREFIX}/include/tarantool when libcurl is included as a bundled library or in a static build (gh-4559).

Тестирование

  • Tarantool CI/CD has migrated to GitHub Actions (gh-5662).
  • Single node Jepsen testing now runs on per-push basis (gh-5736).
  • A self-sufficient LuaJIT testing environment has been implemented. As a result, LuaJIT build system is now partially ported to CMake and all testing machinery is enclosed within the tarantool/luajit repository (gh-4862, gh-5470).
  • Python 3 is now the default in the test infrastructure (gh-5652).

Исправленные ошибки

Core

  • The lbox_ctl_is_recovery_finished() function no longer returns true when recovery is still in progress.
  • A memory corruption bug has been fixed in netbox. The memory of a struct error which is still used will no longer be freed prematurely because of the wrong order of ffi.gc and ffi.cast calls.
  • Relay can no longer time out while a replica is joining or syncing with the master. (gh-5762).
  • An issue with missing «path» value of index schema fetched by netbox has been fixed (gh-5451).
  • Extensive usage of uri and uuid modules with debug log level no longer leads to crashes or corrupted results of the functions from these modules. Same problem is resolved for using these modules from the callbacks passed to ffi.gc(), and for some functions from the modules fio, box.tuple, and iconv (gh-5632).
  • The new wal_cleanup_delay option can prevent early cleanup of *.xlog files, needed by replicas. Such cleanup used to result in a XlogGapError (gh-5806).
  • Appliers will no longer cause errors with Unknown request type 40 during a final join when the master has synchronous spaces (gh-5566).
  • Added memtx MVCC tracking of read gaps which fixes the problem of phantom reads (gh-5628).
  • Fixed the wrong result of using space:count() with memtx MVCC (gh-5972).
  • Fixed the dirty read after restart while using MVCC with synchronous replication (gh-5973).

Репликация

  • Fixed an issue with an applier hanging on a replica after failing to process a CONFIRM or ROLLBACK message coming from a master.
  • Fixed the issue where master did not send some rows to an anonymous replica which had fallen behind and was trying to register.
  • Fixed the bug when a synchronous transaction could be confirmed and visible on a replica, but then not confirmed or invisible again after restart. It was more likely to happen on memtx spaces with memtx_use_mvcc_engine enabled (gh-5213).
  • Fixed the recovery of a rolled back multi-statement synchronous transaction which could lead to the transaction being applied partially, and to recovery errors. It happened in case the transaction worked with non-sync spaces (gh-5874).
  • Fixed a bug in synchronous replication when rolled back transactions could reappear after reconnecting a sufficiently old instance (gh-5445).

Swim

  • Fixed an issue where <swim_instance>:broadcast() did not work on non-local addresses and spammed «Permission denied» errors to the log. After instance termination it could return a non-0 exit code even if there were no errors in the script, and then spam the same error again (gh-5864).
  • Fixed the crash on attempts to call swim:member_by_uuid() with no arguments or with nil/box.NULL (gh-5951).
  • Fixed the crash on attempts to pass an object of a wrong type to __serialize method of a swim member in Lua (gh-5952).

Lua

  • Fixed the -e option, when tarantool used to enter the interactive mode when stdin is a TTY. Now, tarantool -e 'print"Hello"' doesn’t enter the interactive mode, but just prints «Hello» and exits (gh-5040).
  • Fixed a leak of a tuple object in key_def:compare_with_key(tuple, key), which had occurred when the serialization of the key failed (gh-5388).

SQL

  • The string received by a user-defined C or Lua function will no longer be different from the string passed to the function. This could happen when the string passed from SQL had contained \\0 (gh-5938).
  • SQL SELECT or SQL UPDATE on UUID or DECIMAL field will not cause a SEGMENTATION FAULT anymore (gh-5011, gh-5704, gh-5913).
  • Fixed an issue with wrong results of SELECT with GROUP BY which occurred when one of the selected values was VARBINARY and not directly obtained from the space (gh-5890).

LuaJIT

  • Fixed a double gc_cdatanum decrementing in LuaJIT platform metrics which occurred when a finalizer was set for a GCсdata object (gh-5820).

Build

  • Fix building on FreeBSD (incomplete definition of type struct sockaddr) (gh-5748).

  • The already downloaded static build dependencies will not be fetched repeatedly (gh-5761).

  • Recovering with force_recovery option now deletes vylog files which are newer than the snapshot. It helps an instance recover after incidents during a checkpoint (gh-5823).

  • Fixed the libcurl configuring when Tarantool itself has been configured with cmake3 command and there was no cmake command in the PATH (gh-5955).

    This affects building Tarantool from sources with bundled libcurl (it is the default mode).

Tarantool 2.6.2

Release: v. 2.6.2 Date: 2020-12-30 Tag: 2.6.2-0-g34d504d

Общие сведения

2.6.2 is the first stable version of the 2.6 release series. It introduces one improvement and resolves 21 bugs since 2.6.1.

The “stable” label means that we have all planned features implemented and we see no high-impact issues. However, if you encounter an issue, feel free to report it on GitHub.

Совместимость

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Изменения или добавления функциональности

Репликация

  • It is now possible to specify synchro quorum as a function of a number N of registered replicas instead of a const number, for example:

    box.cfg{replication_synchro_quorum = "N/2 + 1"}

    Only the non-anonymous bootstrapped replicas amount to N. The expression should respect synchro guarantees: at least 50% of the cluster size + 1. The expression value is re-evaluated automatically inside of Tarantool when new replicas appear or old ones are removed (gh-5446).

Lua

  • Show JSON tokens themselves instead of token names T_* in the JSON decoder error messages (gh-4339).
  • Show a decoding context in the JSON decoder error messages (gh-4339).

Build

  • Deploy packages for Fedora 32 (gh-4966).
  • Deploy packages for Debian Bullseye (gh-5638).

Исправленные ошибки

Core

  • fiber.cond:wait() now correctly throws an error when a fiber is cancelled, instead of ignoring the timeout and returning without any signs of an error (gh-5013).
  • Fixed a memory corruption issue, which was most visible on macOS, but could affect any system (gh-5312).
  • A dynamic module now gets correctly unloaded from memory in case of an attempt to load a non-existing function from it (gh-5475).
  • A swim:quit() call now can’t result in a crash (gh-4570).
  • Snapshot recovery with no JSONPath or multikey indices involved now has normal performance (gh-4774).

Репликация

  • A false-positive “too long WAL write” message no longer appears for synchronous transactions (gh-5139).
  • A box.ctl.wait_rw() call could return when the instance was not in fact writable due to having foreign synchronous transactions. As a result, there was no proper way to wait until the automatically elected leader would become writable. Now box.ctl.wait_rw() works correctly (gh-5440).
  • Fixed a couple of crashes on various tweaks of election mode (gh-5506).
  • Now box.ctl.clear_synchro_queue tries to commit everything that is present on the node. In order to do so it waits for other instances to replicate the data for replication_synchro_quorum seconds. In case timeout passes and quorum was not reached, nothing is rolled back (gh-5435).

SQL

  • Data changes in read-only mode are now forbidden (gh-5231).
  • Query execution now does not occasionally raise an unrelated error “Space ‘0’ does not exist” (gh-5592).
  • Coinciding names of temporary files (used to store data during execution) having two instances running on the same machine no longer cause a segfault (gh-5537).
  • The return value of ifnull() built-in function is now of a correct type.
  • SQL calling Lua functions with box calls inside can no longer result in a memory corruption (gh-5427).

LuaJIT

  • Dispatching __call metamethod no longer causes address clashing (gh-4518, gh-4649).
  • Fixed a false positive panic when yielding in debug hook (gh-5649).

Lua

  • An attempt to use a net.box connection which is not established yet now results in a correctly reported error (gh-4787).
  • Fixed a NULL dereference on error paths in merger which usually happened on a ‘wrong’ key_def (gh-5450).
  • Calling key_def.compare_with_key() with an invalid key no longer causes a segfault (gh-5307).
  • Fixed a hang which occured when tarantool ran a user script with the -e option and this script exited with an error (like with tarantool -e 'assert(false)') (gh-4983).

Memtx

  • The on_schema_init triggers now can’t cause duplicates in primary key (gh-5304).

Tarantool 2.6.1

Release: v. 2.6.1 Date: 2020-10-22 Tag: 2.6.1-0-gcfe0d1a

Общие сведения

2.6.1 is the beta version of the 2.6 release series.

This release introduces roughly 17 features and resolves 22 bugs since the 2.5.1 version. There may be bugs in less common areas. If you find any, feel free to report an issue at GitHub.

Notable changes are:

Совместимость

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

There are changes labeled with [Breaking change]. It means that the old behavior was considered error-prone and therefore changed to protect users from unintended mistakes. However, there is a little probability that someone can lean on the old behavior, and this label is to bring attention to the things that have been changed.

Изменения или добавления функциональности

Core

Vinyl

Rework upsert operation in vinyl so that now (gh-5107):

  • if upsert can’t be applied it is skipped and corresponding error is logged (gh-1622);
  • upserts now follow associative property: the result of several upserts does not depend on the order of their application (gh-5105);
  • upserts referring to -1 fieldno are handled correctly now (gh-5087).
  • there’s no more upserts squash procedure: upserts referring to the same field with arithmetic operations are not merged into one operation since resulting upsert might not be applied - as a result both upserts would be ignored (meanwhile only one should be).

LuaJIT

  • [Breaking change] Introduce LuaJIT platform metrics (gh-5187). Read more: LuaJIT metrics.
    • This change introduces new builtin library “misc” that may conflict with user’s modules.

SQL

  • SQL views are not alterable anymore. Beforehand it led to the undefined behaviour.
  • Introduce “automatic index” optimization. Ephemeral space with single index can be created to store and speed-up intermediate results access during query execution (gh-4933).

Репликация

  • Automated leader election based on Raft algorithm (gh-1146). Read more: Automated leader election.
  • When election is enabled, a newly elected leader will automatically finish all the synchronous transactions, created by the old leader (gh-5339).

Build

  • Tarantool static build is enhanced in scope of gh-5095. It can be built on the host machine with no Docker at all. As a result it can be built using the OSX environment.

Разное

  • Add all exported symbols from bundled libcurl library (gh-5223)
  • Add fselect method that is similar to select, but formats results like mysql would (gh-5161).

Module API

  • Exposed the box region, key_def and several other functions in order to implement external tuple.keydef and tuple.merger modules on top of them (gh-5273, gh-5384).

Исправленные ошибки

Core

  • Fixed a bug related to ignoring internal getaddrinfo errors on macOS in logger (gh-4138).
  • Fixed a crash when JSON tuple field access was used to get a multikey indexed field, and when a JSON contained [*] in the beginning (gh-5224).
  • Fixed msgpack extension types decoding error message (gh-5016).
  • Dropped restrictions on nullable multikey index root. They were introduced due to inaccuracy in multikey index realization. It is now fixed. Also all fields are now nullable by default as it was before 2.2.1 (gh-5192).
  • Fixed fibers switch-over to prevent JIT machinery misbehavior. Trace recording is aborted when fiber yields the execution. The yield occurring while the compiled code is being run (it’s likely a function with a yield underneath called via LuaJIT FFI) leads to the platform panic (gh-1700, gh-4491).
  • Fixed fibers switch-over to prevent implicit GC disabling. The yield occurring while user-defined __gc metamethod is running leads to the platform panic.

Репликация

  • Fixed a bug when a rolled back synchronous transaction could become committed after restart (gh-5140).
  • Fixed crash in synchronous replication when master’s local WAL write fails (gh-5146).
  • Instance will terminate if a synchronous transaction confirmation or rollback fail. Before it was undefined behavior (gh-5159).
  • Snapshot could contain changes from a rolled back synchronous transaction (gh-5167).
  • Fixed a crash when synchronous transaction’s rollback and confirm could be written simultaneously for the same LSN (gh-5185).
  • Fixed a crash when replica cleared synchronous transaction queue, while it was not empty on master (gh-5195).
  • During recovery of synchronous changes from snapshot the instance could crash (gh-5288).
  • Having synchronous rows in the snapshot could make the instance hang on recovery (gh-5298).
  • Anonymous replica could be registered and could prevent WAL files removal (gh-5287).
  • XlogGapError is not a critical error anymore. It means, box.info.replication will show upstream status as ‘loading’ if the error was found. The upstream will be restarted until the error is resolved automatically with a help of another instance, or until the replica is removed from box.cfg.replication (gh-5287).

LuaJIT

  • Fixed the error occurring on loading luajit-gdb.py with Python 2 (gh-4828).

Lua

  • Fixed a bug related to ignoring internal getaddrinfo errors. Now they can be thrown out by Lua socket functions (gh-4138).
  • Fixed: import of table.clear() method (gh-5210). Affected versions: all 2.6.* until 2.6.0-53-g09aa813 (exclusive).
  • Fixed unhandled Lua error that may lead to memory leaks and inconsistencies in <space_object>:frommap(), <key_def_object>:compare(), <merge_source>:select() (gh-5382).

Memtx

Module API

  • Get rid of typedef redefinitions for compatibility with C99 (gh-5313).

Tarantool 2.5.3

Release: v. 2.5.3 Date: 2020-12-30 Tag: 2.5.3-0-gf93e480

Общие сведения

2.5.3 is the second stable version of the 2.5 release series. It introduces one improvement and resolves 19 bugs since 2.5.2.

The “stable” label means that we have all planned features implemented and we see no high-impact issues. However, if you encounter an issue, feel free to report it on GitHub.

Совместимость

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Изменения или добавления функциональности

Репликация

  • It is now possible to specify synchro quorum as a function of a number N of registered replicas instead of a const number, for example:

    box.cfg{replication_synchro_quorum = "N/2 + 1"}

    Only the non-anonymous bootstrapped replicas amount to N. The expression should respect synchro guarantees: at least 50% of the cluster size + 1. The expression value is re-evaluated automatically inside of Tarantool when new replicas appear or old ones are removed (gh-5446).

Lua

  • Show JSON tokens themselves instead of token names T_* in the JSON decoder error messages (gh-4339).
  • Show a decoding context in the JSON decoder error messages (gh-4339).

Build

  • Deploy packages for Fedora 32 (gh-4966).
  • Deploy packages for Debian Bullseye (gh-5638).

Исправленные ошибки

Core

  • fiber.cond:wait() now correctly throws an error when a fiber is cancelled, instead of ignoring the timeout and returning without any signs of an error (gh-5013).
  • Fixed a memory corruption issue, which was most visible on macOS, but could affect any system (gh-5312).
  • A dynamic module now gets correctly unloaded from memory in case of an attempt to load a non-existing function from it (gh-5475).
  • A swim:quit() call now can’t result in a crash (gh-4570).
  • Snapshot recovery with no JSONPath or multikey indices involved now has normal performance (gh-4774).

Репликация

  • A false-positive “too long WAL write” message no longer appears for synchronous transactions (gh-5139).
  • A box.ctl.wait_rw() call could return when the instance was not in fact writable due to having foreign synchronous transactions. As a result, there was no proper way to wait until the automatically elected leader would become writable. Now box.ctl.wait_rw() works correctly (gh-5440).

SQL

  • Data changes in read-only mode are now forbidden (gh-5231).
  • Query execution now does not occasionally raise an unrelated error “Space ‘0’ does not exist” (gh-5592).
  • Coinciding names of temporary files (used to store data during execution) having two instances running on the same machine no longer cause a segfault (gh-5537).
  • The return value of ifnull() built-in function is now of a correct type.
  • SQL calling Lua functions with box calls inside can no longer result in a memory corruption (gh-5427).

LuaJIT

  • Dispatching __call metamethod no longer causes address clashing (gh-4518, gh-4649).
  • Fixed a false positive panic when yielding in debug hook (gh-5649).

Lua

  • An attempt to use a net.box connection which is not established yet now results in a correctly reported error (gh-4787).
  • Fixed a NULL dereference on error paths in merger which usually happened on a ‘wrong’ key_def (gh-5450).
  • Calling key_def.compare_with_key() with an invalid key no longer causes a segfault (gh-5307).
  • Fixed a hang which occured when tarantool ran a user script with the -e option and this script exited with an error (like with tarantool -e 'assert(false)') (gh-4983).

Memtx

Tarantool 2.5.2

Release: v. 2.5.2 Date: 2020-10-22 Tag: 2.5.2-1-gf63c43b

Общие сведения

This release resolves roughly 25 issues since the 2.5.2 version. There may be bugs in less common areas. If you find any, feel free to report an issue at GitHub.

Совместимость

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Изменения или добавления функциональности

Core

  • New function space:alter(options) to change some space settings without recreation nor touching _space space. Read more.

Module API

  • Exposed the box region, key_def and several other functions in order to implement external tuple.keydef and tuple.merger modules on top of them (gh-5273, gh-5384).

Исправленные ошибки

Core

  • Fixed a bug related to ignoring internal getaddrinfo errors on macOS in logger (gh-4138).
  • Fixed a crash when JSON tuple field access was used to get a multikey indexed field, and when a JSON contained [*] in the beginning (gh-5224).
  • Fixed msgpack extension types decoding error message (gh-5016).
  • Dropped restrictions on nullable multikey index root. They were introduced due to inaccuracy in multikey index realization. It is now fixed. Also all fields are now nullable by default as it was before 2.2.1 (gh-5192).
  • Fixed fibers switch-over to prevent JIT machinery misbehavior. Trace recording is aborted when fiber yields the execution. The yield occurring while the compiled code is being run (it’s likely a function with a yield underneath called via LuaJIT FFI) leads to the platform panic (gh-1700, gh-4491).
  • Fixed fibers switch-over to prevent implicit GC disabling. The yield occurring while user-defined __gc metamethod is running leads to the platform panic.

Репликация

  • Fixed a bug when a rolled back synchronous transaction could become committed after restart (gh-5140).
  • Fixed crash in synchronous replication when master’s local WAL write fails (gh-5146).
  • Instance will terminate if a synchronous transaction confirmation or rollback fail. Before it was undefined behavior (gh-5159).
  • Snapshot could contain changes from a rolled back synchronous transaction (gh-5167).
  • Fixed a crash when synchronous transaction’s rollback and confirm could be written simultaneously for the same LSN (gh-5185).
  • Fixed a crash when replica cleared synchronous transaction queue, while it was not empty on master (gh-5195).
  • During recovery of synchronous changes from snapshot the instance could crash (gh-5288).
  • Having synchronous rows in the snapshot could make the instance hang on recovery (gh-5298).
  • Anonymous replica could be registered and could prevent WAL files removal (gh-5287).
  • XlogGapError is not a critical error anymore. It means, box.info.replication will show upstream status as ‘loading’ if the error was found. The upstream will be restarted until the error is resolved automatically with a help of another instance, or until the replica is removed from box.cfg.replication (gh-5287).

LuaJIT

  • Fixed the error occurring on loading luajit-gdb.py with Python 2 (gh-4828).

Lua

  • Fixed a bug related to ignoring internal getaddrinfo errors. Now they can be thrown out by Lua socket functions (gh-4138).
  • Fixed: import of table.clear() method (gh-5210). Affected versions: 2.5.0-265-g3af79e70b (inclusive) to 2.5.1-52-ged9a156 (exclusive).
  • Fixed unhandled Lua error that may lead to memory leaks and inconsistencies in <space_object>:frommap(), <key_def_object>:compare(), <merge_source>:select() (gh-5382).

SQL

  • SQL view are not alterable anymore. Beforehand it led to undefined behavior.

Разное

  • Fixed potential lag on boot up procedure when system’s password database is slow in access (gh-5034).

Module API

  • Get rid of typedef redefinitions for compatibility with C99 (gh-5313).

Tarantool 2.5.1

Release: v. 2.5.1 Date: 2020-07-17 Tag: 2.5.1-1-g635f6e5

Общие сведения

2.5.1 is the beta version of the 2.5 release series.

This release introduces roughly 11 features and resolves 34 bugs since the 2.4.1 version. There may be bugs in less common areas. If you find any, feel free to report an issue at GitHub.

Notable changes are:

Совместимость

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

There are changes labeled with [Breaking change]. It means that the old behavior was considered error-prone and therefore changed to protect users from unintended mistakes. However, there is a little probability that someone can lean on the old behavior, and this label is to bring attention to the things that have been changed.

Изменения или добавления функциональности

Core

  • [Breaking change] box.session.push() parameter sync is deprecated and deleted. It does not work anymore, and a usage attempt leads to an error (gh-4689).
  • [Breaking change] Define new rules for implicit cast for assignment operation in SQL (gh-3809). Read more: Implicit string/numeric cast.
  • Symbols of the Tarantool executable are not masked anymore. Some private symbols may become visible and available for FFI and dlopen() + dlsym() (gh-2971).
  • Add ability to set up logging early without configuring the box engine (gh-689).
  • To retrieve information about memory usage, box.info.memory() can be used (gh-4688).

Vinyl

  • box.snapshot() now ignores throttling of the scheduler and forces the dump process immediately (gh-3519).

SQL

  • Use naming pattern “COLUMN_N” for automatically generated column’s names (gh-3962). Read more: Select list.

Репликация

  • Add box.info.replication_anon(). When called, it lists anonymous replicas in the same format as box.info.replication, the only exception is that anonymous replicas are indexed by their uuid strings (gh-4900).
  • Allow anonymous replicas to be followed by other ones (gh-4696).
  • Synchronous replication can be enabled per-space using the is_sync space option (gh-4842).

Build

  • Add initial support for OpenBSD (gh-4967).

Разное

  • Don’t start the ‘example’ instance after installing Tarantool (gh-4507).

    Before this release, the Tarantool package for Debian and Ubuntu automatically enable and start the ‘example’ instance, which listens on the TCP port 3301. Starting from this release, the instance file is installed to /etc/tarantool/instances.available/example.lua, but is not enabled by default and not started anymore. One may perform the following actions to enable and start it:

    ln -s /etc/tarantool/instances.available/example.lua \
    /etc/tarantool/instances.enabled/example.lua
systemctl start tarantool@example

    The existing configuration will not be updated automatically at package update, so manual actions are required to stop and disable the instance (if it is not needed, of course):

    systemctl stop tarantool@example
rm /etc/tarantool/instances.enabled/example.lua

  • When LTO is enabled, Luajit is built with it (gh-3743).

Исправленные ошибки

Core

  • Fixed assert outdated due to multikey index arrival (gh-5132).
  • Fixed a bug in altering a normal index to a functional one (n/a).
  • Fixed a couple of internal symbols dangling in global namespace _G (gh-4812).
  • Fixed bug when on_shutdown triggers were not executed after EOF (gh-4703).
  • Fixed inability to handle ULL constants in Lua mode console (gh-4682).
  • Fixed a bug in C module reloading (gh-4945).
  • Fixed confusing implicit requirements for tuple fields (gh-5027).
  • Added needed key validation to space_before_replace (gh-5017).
  • Fixed check of index field map size which led to crash (gh-5084).
  • Fixed NULL pointer dereference when merger is called via the binary protocol (say, via net.box) (gh-4954).
  • Fix wrong mpsgpack extension type in an error message at decoding (gh-5017).
  • Fixed crash when invalid JSON was used in update() (gh-5135).

Репликация

  • Fixed possible ER_TUPLE_FOUND error when bootstrapping replicas in an 1.10/2.1.1 cluster (gh-4924).
  • Fixed tx boundary check for half-applied txns (gh-5125).
  • Fixed replication tx boundaries after local space rework (gh-4928).

Lua

  • Added format string usage to form a CustomError message (gh-4903). Read more: Custom error.
  • Fixed error while closing socket.tcp_server socket (gh-4087).
  • Extended box.error objects reference counter to 64 bit to prevent possible overflow (gh-4902).
  • Refactored Lua table encoding: removed excess Lua function object and left protected Lua frame only for the case __serialize is a function to improve msgpack.encode() performance (no GH issue).
  • Improved Lua call procedure for the case of built-in functions. Prepared GCfunc object is used instead of temporary one, resulting in 3-6% garbage collection reduction.
  • Enabled luacheck in continuous integration (no GH issue).
  • Fixed warnings (two of them were real bugs!) found by luacheck in a source code (no GH issue).

SQL

  • Fixed wrong order of rows as a result of query containing column of SCALAR type in ORDER BY clause (gh-4697).
  • Fixed bug with the display of collation for scalar fields in <SELECT> result, when sql_full_metadata is enabled (gh-4755).
  • Block using HASH indexes in SQL since scheduler is unable to use it properly (gh-4659).
  • Fixed races and corner cases in box (re)configuration (gh-4231).

Vinyl

  • Fixed crash during compaction due to tuples with size exceeding vinyl_max_tuple_size setting (gh-4864).
  • Fixed crash during recovery of vinyl index due to the lack of file descriptors (gh-4805).
  • Fixed crash during executing upsert changing primary key in debug mode (gh-5005).
  • Fixed crash due to triggered dump process during secondary index creation (gh-5042).
  • Fixed crash/deadlock (depending on build type) during dump process scheduling and concurrent DDL operation (gh-4821).
  • Fixed crash during read of prepared but still not yet not committed statement (gh-3395).
  • Fixed squashing set and arithmetic upsert operations (gh-5106).
  • Created missing folders for vinyl spaces and indexes if needed to avoid confusing fails of tarantool started from backup (gh-5090).
  • Fixed crash during squash of many (more than 4000) upserts modifying the same key (gh-4957).

Memtx

  • Fixed concurrent replaces on index building. Tuples are now referenced on all needed execution paths (gh-4973).

Разное

  • Fixed a possible stacked diagnostics crash due to incorrect reference count (gh-4887).

Tarantool 2.4.3

Release: v. 2.4.3 Date: 2020-10-22 Tag: 2.4.3-1-g986fab7

Общие сведения

This release resolves roughly 13 issues since the 2.4.2 version. There may be bugs in less common areas. If you find any, feel free to report an issue at GitHub.

Совместимость

Tarantool 2.x is backward compatible with Tarantool 1.10.x in the binary data layout, client-server protocol, and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Изменения или добавления функциональности

Module API

  • Exposed the box region, key_def and several other functions in order to implement external tuple.keydef and tuple.merger modules on top of them (gh-5273, gh-5384).

Исправленные ошибки

Core

  • Fixed a crash when JSON tuple field access was used to get a multikey indexed field, and when a JSON contained [*] in the beginning (gh-5224).
  • Fixed msgpack extension types decoding error message (gh-5016).
  • Dropped restrictions on nullable multikey index root. They were introduced due to inaccuracy in multikey index realization. It is now fixed. Also all fields are now nullable by default as it was before 2.2.1 (gh-5192).
  • Fixed fibers switch-over to prevent JIT machinery misbehavior. Trace recording is aborted when fiber yields the execution. The yield occurring while the compiled code is being run (it’s likely a function with a yield underneath called via LuaJIT FFI) leads to the platform panic (gh-1700, gh-4491).
  • Fixed fibers switch-over to prevent implicit GC disabling. The yield occurring while user-defined __gc metamethod is running leads to the platform panic.

Репликация

  • Anonymous replica could be registered and could prevent WAL files removal (gh-5287).
  • XlogGapError is not a critical error anymore. It means, box.info.replication will show upstream status as ‘loading’ if the error was found. The upstream will be restarted until the error is resolved automatically with a help of another instance, or until the replica is removed from box.cfg.replication (gh-5287).

LuaJIT

  • Fixed the error occurring on loading luajit-gdb.py with Python2 (gh-4828).

Lua

  • Fixed unhandled Lua error that may lead to memory leaks and inconsistencies in <space_object>:frommap(), <key_def_object>:compare(), <merge_source>:select() (gh-5382).

SQL

  • SQL view are not alterable anymore. Beforehand it led to undefined behavior.

Разное

  • Fixed potential lag on boot up procedure when system’s password database is slow in access (gh-5034).

Module API

  • Get rid of typedef redefinitions for compatibility with C99 (gh-5313).

Tarantool 2.4.2

Release: v. 2.4.2 Date: 2020-07-17 Tag: 2.4.2-1-g3f00d29

Общие сведения

2.4.2 is the first stable version of the 2.4 release series. The label stable means we have all planned features implemented and we see no high-impact issues.

This release resolves roughly 32 issues since the latest beta version. There may be bugs in less common areas, please feel free to file an issue at GitHub.

Совместимость

Tarantool 2.x is backward compatible with Tarantool 1.10.x in binary data layout, client-server protocol and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Изменения или добавления функциональности

Core

  • box.session.push() parameter sync is deprecated. A warning is printed when the sync is used, but it still works. It is removed in the next version (gh-4689).

Разное

  • Don’t start ‘example’ instance after installing Tarantool (gh-4507).

    Before this release tarantool package for Debian and Ubuntu automatically enable and start ‘example’ instance, which listens on the TCP port 3301. Starting from this release the instance file is installed to /etc/tarantool/instances.available/example.lua, but is not enabled by default and not started anymore. One may perform the following actions to enable and start it:

    ln -s /etc/tarantool/instances.available/example.lua \
    /etc/tarantool/instances.enabled/example.lua
systemctl start tarantool@example

    Existing configuration will not be updated automatically at package update, so manual actions are required to stop and disable the instance (if it is not needed, of course):

    systemctl stop tarantool@example
rm /etc/tarantool/instances.enabled/example.lua

Исправленные ошибки

Core

  • Fixed a bug in altering a normal index to a functional one (n/a).
  • Fixed a couple of internal symbols dangling in global namespace _G (gh-4812).
  • Fixed bug when on_shutdown triggers were not executed after EOF (gh-4703).
  • Fixed inability to handle ULL constants in Lua mode console (gh-4682).
  • Fixed a bug in C module reloading (gh-4945).
  • Fixed assert outdated due to multikey index arrival (gh-5132).
  • Fixed confusing implicit requirements for tuple fields (gh-5027).
  • Added needed key validation to space_before_replace (gh-5017).
  • Fixed check of index field map size which led to crash (gh-5084).
  • Fixed NULL pointer dereference when merger is called via the binary protocol (say, via net.box) (gh-4954).
  • Fix wrong mpsgpack extension type in an error message at decoding (gh-5017).
  • Fixed crash when invalid JSON was used in update() (gh-5135).

Репликация

  • Fixed possible ER_TUPLE_FOUND error when bootstrapping replicas in an 1.10/2.1.1 cluster (gh-4924).
  • Fixed tx boundary check for half-applied txns (gh-5125).
  • Fixed replication tx boundaries after local space rework (gh-4928).

Lua

  • Added format string usage to form a CustomError message (gh-4903). Read more: Custom error.
  • Fixed error while closing socket.tcp_server socket (gh-4087).
  • Extended box.error objects reference counter to 64 bit to prevent possible overflow (gh-4902).

SQL

  • Fix wrong order of rows as a result of query containing column of SCALAR type in ORDER BY clause (gh-4697).
  • Fix bug with the display of collation for scalar fields in <SELECT> result, when sql_full_metadata is enabled (gh-4755).
  • Block using HASH indexes in SQL since scheduler is unable to use it properly (gh-4659).
  • Fixed races and corner cases in box (re)configuration (gh-4231).

Vinyl

  • Fixed crash during compaction due to tuples with size exceeding vinyl_max_tuple_size setting (gh-4864).
  • Fixed crash during recovery of vinyl index due to the lack of file descriptors (gh-4805).
  • Fixed crash during executing upsert changing primary key in debug mode (gh-5005).
  • Fixed crash due to triggered dump process during secondary index creation (gh-5042).
  • Fixed crash/deadlock (depending on build type) during dump process scheduling and concurrent DDL operation (gh-4821).
  • Fixed crash during read of prepared but not committed statement (gh-3395).
  • Fixed squashing set and arithmetic upsert operations (gh-5106).
  • Create missing folders for vinyl spaces and indexes if needed to avoid confusing fails of tarantool started from backup (gh-5090).
  • Fixed crash during squash of many (more than 4000) upserts modifying the same key (gh-4957).

Memtx

  • Fixed concurrent replaces on index building. Tuples are now referenced on all needed execution paths (gh-4973).

Tarantool 2.4.1

Release: v. 2.4.1 Date: 2020-04-20 Tag: 2.4.1-1-g6c75f80

Общие сведения

2.4.1 is the beta version of the 2.4 release series.

This release introduces roughly 20 features and resolves 92 bugs since the 2.3.1 version. There may be bugs in less common areas. If you find any, feel free to report an issue at GitHub.

Notable changes are:

Совместимость

Tarantool 2.x is backward compatible with Tarantool 1.10.x in binary data layout, client-server protocol and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Изменения или добавления функциональности

Core

Lua

  • Added popen built-in module (gh-4031).

    The module provides popen implementation that is integrated with tarantool’s event loop (like built-in fio and socket modules).

    It support bidirectional communication with a process: the module can feed input to a process and capture its output. This way it allows to run streaming programs (like grep) and even work interactively with outside REPL (say, python -i).

    A key feature of the implementation is that it uses vfork() under hood and so does not copy virtual memory tables. Copying of them may be quite time consuming: os.execute() takes ~2.5 seconds when 80 GiB is allocated for memtx. Moreover, when memory overcommit is disabled (which is default) it would be not possible to fork a process when more then half of available physical memory is mapped to tarantool’s process.

    The API should be considered as beta: it is quite basic and will be extended with convenience features. On the other hand, it may be changed in a backward-incompatible manner in the future releases if it will be valuable enough.

    For more details, refer to the popen module documentation.

  • fio descriptors are closed on garbage collection (gh-4727). Read more in description of fio.open().

  • fio.tempdir() uses the $TMPDIR environment variable as a path indication to create temporary directories (gh-4794).

  • Expose lua_checktuple function (gh-2553).

  • fiber.name maximal length is extended to 255 (gh-4394).

  • Add tarantoolctl rocks commands: build, config, download, init, lint, new_version, purge, which, write_rockspec (gh-4629). Read more in tarantoolctl-module_management.

Разное

  • box.info.listen: a new variable in the box.info. Shows the real port when bound to the port 0. For example, if the listen parameter of box.cfg is set to 127.0.0.1:0, the box.info.listen shows 127.0.0.1:<real_port> (gh-4620). Read more: box.info.listen.
  • sequence:current(): a new function to get the current sequence value without changing it (gh-4752). Read more: sequence_object:current().

Исправленные ошибки

Core

  • fiber.storage is cleaned between requests, and can be used as a request-local storage. Previously fiber.storage could contain some old values in the beginning of an iproto request execution, and it needed to be nullified manually. Now the cleanup is unneeded (gh-4662).
  • tuple/space/index:update()/upsert() were fixed not to turn a value into an infinity when a float value was added to or subtracted from a float column and exceeded the float value range (gh-4701).
  • Fix potential execution abort when operating the system runs under heavy memory load (gh-4722).
  • Make RTREE indexes handle the out of memory error: before this fix, OOM during the recovery of an RTREE index resulted in segmentation fault (gh-4619).
  • Fix the error message returned on using an already dropped sequence (gh-4753).
  • Add cancellation guard to avoid WAL thread stuck (gh-4127).
  • Fix execution abort when memtx_memory and vinyl_memory are set to more than 4398046510080 bytes. Now an error message is returned (gh-4705).
  • box.error.new() does not add a created error to the Tarantool’s diagnostic area anymore (gh-4778). Read more:
  • Add Lua output format support for box.session.push() (gh-4686).

Репликация

  • Fix rebootstrap procedure not working in case replica itself is listed in box.cfg.replication (gh-4759).
  • Fix possible user password leaking via replication logs (gh-4493).
  • Refactor vclock map to be exactly 4 bytes in size to fit all 32 replicas regardless of the compiler used (see in this commit).
  • Fix crash when the replication applier rollbacks a transaction (gh-4730, gh-4776).
  • Fix segmentation fault on master side when one of the replicas transitions from anonymous to normal (gh-4731).
  • Local space operations are now counted in 0th vclock component. Every instance may have its own 0-th vclock component not matching others’. Local space operations are not replicated at all, even as NOPs (gh-4114).
  • Gc consumers are now ordered by their vclocks and not by vclock signatures. Only the WALS that contain no entries needed by any of the consumers are deleted (gh-4114).

Lua

  • json: :decode() does not spoil instance’s options with per-call ones (when it is called with the second argument) (gh-4761).
  • Handle empty input for uri.format() properly (gh-4779).
  • os.environ() is now changed when os.setenv() is called (gh-4733).
  • netbox.self:call/eval() now returns the same types as netbox_connection:call/eval. Previously it could return a tuple or box.error cdata (gh-4513).
  • box.tuple.* namespace is cleaned up from private functions. box.tuple.is() description is added to documentation (gh-4684).
  • tarantoolctl rocks search: fix the --all flag (gh-4529).
  • tarantoolctl rocks remove: fix the --force flag (gh-3632).
  • libev: backport fix for listening for more then 1024 file descriptors on Mac OS (gh-3867).

SQL

  • Fix box.stat() behavior: now it collects statistics on the PREPARE and EXECUTE methods as expected (gh-4756).
  • Add ability to drop any table constraint using the following statement: ALTER TABLE  <table_name> DROP CONSTRAINT <constraint_name>. Previously, it was possible to drop only foreign key constraints with such a statement (gh-4120). Read more in Alter Table.
  • “No such constraint” error now contains the name of the table this constraint belongs to.
  • Add an empty body to the UNPREPARE IProto response (gh-4769).
  • Reset all the placeholders’ bound values after execution of a prepared statement (gh-4825).
  • The inserted values are inserted in the order in which they are given in case of INSERT into space with autoincrement (gh-4256).

LuaJIT

  • __pairs/__ipairs metamethods handling is removed since we faced the issues with the backward compatibility between Lua 5.1 and Lua 5.2 within Tarantool modules as well as other third party code (gh-4770).
  • Introduce luajit-gdb.py extension with commands for inspecting LuaJIT internals. The extension obliges one to provide gdbinfo for libluajit, otherwise loading fails. The extension provides the following commands:
    • lj-arch dumps values of LJ_64 and LJ_GC64 macro definitions
    • lj-tv dumps the type and GCobj info related to the given TValue
    • lj-str dumps the contents of the given GCstr
    • lj-tab dumps the contents of the given GCtab
    • lj-stack dumps Lua stack of the given lua_State
    • lj-state shows current VM, GC and JIT states
    • lj-gc shows current GC stats
  • Fix string to number conversion: current implementation respects the buffer length (gh-4773).
  • “FFI sandwich” (*) detection is introduced. If sandwich is detected while trace recording the recording is aborted. The sandwich detected while mcode execution leads to the platform panic.
  • luaJIT_setmode call is prohibited while mcode execution and leads to the platform panic.

(*) The following stack mix is called FFI sandwich: Lua-FFI -> C routine -> Lua-C API -> Lua VM.

This sort of re-entrancy is explicitly not supported by LuaJIT compiler. For more info see gh-4427.

Vinyl

  • Fix assertion fault due to triggered dump process during secondary index build (gh-4810).

Разное

  • Fix crashes at attempts to use -e and -l command line options concatenated with their values, like this: -eprint(100) (gh-4775).
  • Fix inability to upgrade from 2.1 if there was an automatically generated sequence (gh-4771).
  • Prettify the error message for user.grant(): no extra ’ ’ for universal privileges (gh-714).
  • Update libopenssl version to 1.1.1f since the previous one was EOLed (gh-4830).

Building from sources

Tarantool 2.3.3

Release: v. 2.3.3 Date: 2020-07-17 Tag: 2.3.3-1-g43af95e

Общие сведения

2.3.3 is the last stable version of the 2.3 release series. The label stable means we have all planned features implemented and we see no high-impact issues.

This release resolves roughly 26 issues since the latest stable version. There may be bugs in less common areas, please feel free to file an issue at GitHub.

Please note, this release contains no new features.

Совместимость

Tarantool 2.x is backward compatible with Tarantool 1.10.x in binary data layout, client-server protocol and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Исправленные ошибки

Core

  • Fixed a bug in altering a normal index to a functional one (n/a).
  • Fixed a couple of internal symbols dangling in global namespace _G (gh-4812).
  • Fixed bug when on_shutdown triggers were not executed after EOF (gh-4703).
  • Fixed a bug in C module reloading (gh-4945).
  • Fixed assert outdated due to multikey index arrival (gh-5132).
  • Fixed confusing implicit requirements for tuple fields (gh-5027).
  • Added needed key validation to space_before_replace (gh-5017).
  • Fixed check of index field map size which led to crash (gh-5084).
  • Fixed NULL pointer dereference when merger is called via the binary protocol (say, via net.box) (gh-4954).
  • Fixed crash when invalid JSON was used in update() (gh-5135).

Репликация

  • Fixed possible ER_TUPLE_FOUND error when bootstrapping replicas in an 1.10/2.1.1 cluster (gh-4924).
  • Fixed tx boundary check for half-applied txns (gh-5125).
  • Fixed replication tx boundaries after local space rework (gh-4928).

Lua

  • Fixed error while closing socket.tcp_server socket (gh-4087).

SQL

  • Fixed wrong order of rows as a result of query containing column of SCALAR type in ORDER BY clause (gh-4697).
  • Fixed bug with the display of collation for scalar fields in <SELECT> result, when sql_full_metadata is enabled (gh-4755).
  • Block using HASH indexes in SQL since scheduler is unable to use it properly (gh-4659).
  • Fixed races and corner cases in box (re)configuration (gh-4231).

Vinyl

  • Fixed crash during compaction due to tuples with size exceeding vinyl_max_tuple_size setting (gh-4864).
  • Fixed crash during recovery of vinyl index due to the lack of file descriptors (gh-4805).
  • Fixed crash during executing upsert changing primary key in debug mode (gh-5005).
  • Fixed crash due to triggered dump process during secondary index creation (gh-5042).
  • Fixed crash/deadlock (depending on build type) during dump process scheduling and concurrent DDL operation (gh-4821).
  • Fixed crash during read of prepared but still not yet not committed statement (gh-3395).
  • Fixed squashing set and arithmetic upsert operations (gh-5106).
  • Create missing folders for vinyl spaces and indexes if needed to avoid confusing fails of tarantool started from backup (gh-5090).
  • Fixed crash during squash of many (more than 4000) upserts modifying the same key (gh-4957).

Memtx

  • Fixed concurrent replaces on index building. Tuples are now referenced on all needed execution paths (gh-4973).

Tarantool 2.3.2

Release: v. 2.3.2 Date: 2020-04-20 Tag: 2.3.2-1-g9be641b

Общие сведения

2.3.2 is the first stable version of the 2.3 release series. The label stable means we have all planned features implemented and we see no high-impact issues.

This release resolves roughly 39 issues since the latest beta version. There may be bugs in less common areas, please feel free to file an issue at GitHub.

Please note, this release contains no new features.

Совместимость

Tarantool 2.x is backward compatible with Tarantool 1.10.x in binary data layout, client-server protocol and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Исправленные ошибки

Core

  • fiber.storage is cleaned between requests, and can be used as a request-local storage. Previously fiber.storage could contain some old values in the beginning of an iproto request execution, and it needed to be nullified manually. Now the cleanup is unneeded (gh-4662).
  • tuple/space/index:update()/upsert() were fixed not to turn a value into an infinity when a float value was added to or subtracted from a float column and exceeded the float value range (gh-4701).
  • Fix potential execution abort when operating the system runs under heavy memory load (gh-4722).
  • Make RTREE indexes handle the out of memory error: before this fix, OOM during the recovery of an RTREE index resulted in segmentation fault (gh-4619).
  • Fix the error message returned on using an already dropped sequence (gh-4753).
  • Add cancellation guard to avoid WAL thread stuck (gh-4127).
  • Fix execution abort when memtx_memory and vinyl_memory are set to more than 4398046510080 bytes. Now an error message is returned (gh-4705).
  • Add Lua output format support for box.session.push() (gh-4686).

Репликация

  • Fix rebootstrap procedure not working in case replica itself is listed in box.cfg.replication (gh-4759).
  • Fix possible user password leaking via replication logs (gh-4493).
  • Refactor vclock map to be exactly 4 bytes in size to fit all 32 replicas regardless of the compiler used (https://github.com/tarantool/tarantool/commit/e5679980aa5f813553a95ab7d31f111dd0893df6).
  • Fix crash when the replication applier rollbacks a transaction (gh-4730, gh-4776).
  • Fix segmentation fault on master side when one of the replicas transitions from anonymous to normal (gh-4731).
  • Local space operations are now counted in 0th vclock component. Every instance may have its own 0-th vclock component not matching others’. Local space operations are not replicated at all, even as NOPs (gh-4114).
  • Gc consumers are now ordered by their vclocks and not by vclock signatures. Only the WALS that contain no entries needed by any of the consumers are deleted (gh-4114).

Lua

  • json: :decode() does not spoil instance’s options with per-call ones (when it is called with the second argument) (gh-4761).
  • Handle empty input for uri.format() properly (gh-4779).
  • os.environ() is now changed when os.setenv() is called (gh-4733).
  • netbox.self:call/eval() now returns the same types as netbox_connection:call/eval. Previously it could return a tuple or box.error cdata (gh-4513).
  • box.tuple.* namespace is cleaned up from private functions. box.tuple.is() description is added to documentation (gh-4684).
  • tarantoolctl rocks search: fix the --all flag (gh-4529).
  • tarantoolctl rocks remove: fix the --force flag (gh-3632).
  • libev: backport fix for listening for more then 1024 file descriptors on Mac OS (gh-3867).

SQL

  • Fix box.stat() behavior: now it collects statistics on the PREPARE and EXECUTE methods as expected (gh-4756).
  • Add an empty body to the UNPREPARE IProto response (gh-4769).
  • Reset all the placeholders’ bound values after execution of a prepared statement (gh-4825).
  • The inserted values are inserted in the order in which they are given in case of INSERT into space with autoincrement (gh-4256).

HTTP client

  • When building Tarantool with bundled libcurl, link it with the c-ares library by default (gh-4591).

LuaJIT

  • __pairs/__ipairs metamethods handling is removed since we faced the issues with the backward compatibility between Lua 5.1 and Lua 5.2 within Tarantool modules as well as other third party code (gh-4770).
  • Introduce luajit-gdb.py extension with commands for inspecting LuaJIT internals. The extension obliges one to provide gdbinfo for libluajit, otherwise loading fails. The extension provides the following commands:
    • lj-arch dumps values of LJ_64 and LJ_GC64 macro definitions
    • lj-tv dumps the type and GCobj info related to the given TValue
    • lj-str dumps the contents of the given GCstr
    • lj-tab dumps the contents of the given GCtab
    • lj-stack dumps Lua stack of the given lua_State
    • lj-state shows current VM, GC and JIT states
    • lj-gc shows current GC stats
  • Fix string to number conversion: current implementation respects the buffer length (gh-4773).
  • “FFI sandwich” (*) detection is introduced. If sandwich is detected while trace recording the recording is aborted. The sandwich detected while mcode execution leads to the platform panic.
  • luaJIT_setmode call is prohibited while mcode execution and leads to the platform panic.

(*) The following stack mix is called FFI sandwich:

Lua-FFI -> C routine -> Lua-C API -> Lua VM

This sort of re-entrancy is explicitly not supported by LuaJIT compiler. For more info see gh-4427.

Vinyl

  • Fix assertion fault due to triggered dump process during secondary index build (gh-4810).

Разное

  • Fix crashes at attempts to use -e and -l command line options concatenated with their values, like this: -eprint(100) (gh-4775).
  • Fix inability to upgrade from 2.1 if there was an automatically generated sequence (gh-4771).
  • Update libopenssl version to 1.1.1f since the previous one was EOLed (gh-4830).

Building from sources

Tarantool 2.3.1

Release: v. 2.3.1 Date: 2019-12-31 Tag: 2.3.1-0-g5a1a220

Общие сведения

2.3.1 is the beta version of the 2.3 release series.

This release introduces roughly 38 features and resolves 102 bugs since the 2.2.1 version. There may be bugs in less common areas. If you find any, feel free to report an issue at GitHub.

Notable changes are:

Aside of that many other features have been implemented and considerable amount of bugs have been fixed.

Совместимость

Tarantool 2.x is backward compatible with Tarantool 1.10.x in binary data layout, client-server protocol and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Изменения или добавления функциональности

There are changes labeled with [Breaking change]. It means that the old behaviour was considered error-prone and therefore changed to protect users from unintended mistakes. However, there is a little probability that someone can lean on the old behaviour, and this label is to bring attention to the things that have been changed.

SQL

  • Introduce prepared statements support and prepared statements cache (gh-2592, gh-3292). Using of prepared statements allows to eliminate overhead of transmitting a statement text over a network and parsing it each time before execution. Aside of this, it allows to acquire binding parameters and result set columns metainformation prior to actual execution of a statement. This feature is vital for implementing standard DBMS APIs, such as ODBC and JDBC.

  • [Breaking change] Introduce _session_setting service space as replacement for PRAGMA keyword (gh-4511). All frontends (C, Lua, SQL, binary protocol) can use this space to access or update session settings. Removed count_changes, short_column_names, sql_compound_select_limit, vdbe_addoptrace pragmas. Transformed others into _session_settings tuples.

  • Extend SQL result set metadata (gh-4407), In addition to the name and type fields, the collation, is_nullable, is_autoincrement, and span fields are added. These new fields are shown when the full_metadata session setting is enabled but always sent via binary protocol.

  • Add an ability to disable check constraints (gh-4244). Example: ALTER TABLE foo {ENABLE|DISABLE} CHECK CONSTRAINT bar;. For details of using from Lua, refer to documentation.

  • AUTOINCREMENT for multipart primary key (gh-4217). The auto-increment feature can be set to any INTEGER or UNSIGNED field of PRIMARY KEY using one of the two ways:

    1. AUTOINCREMENT in column definition:

      CREATE TABLE t (i INT, a INT AUTOINCREMENT, PRIMARY KEY (i, a));
CREATE TABLE t (i INT AUTOINCREMENT, a INT, PRIMARY KEY (i, a));

    2. AUTOINCREMENT in PRIMARY KEY definition:

      CREATE TABLE t (i INT, a INT, PRIMARY KEY (i, a AUTOINCREMENT));
CREATE TABLE t (i INT, a INT, PRIMARY KEY (i AUTOINCREMENT, a));

  • Allow to create a view from any CTE (common table expression) using WITH clause (gh-4149).

  • Support user-defined functions in SQL. box.schema.func.create() API has been extended and should be used to make some function available in SQL. For details on fields added, refer to the description here: (doc-879). Usage of legacy mechanismbox.internal.sql_function_create is forbidden now (gh-2200, gh-2233, gh-4113).

  • Scalar functions MIN/MAX are renamed to LEAST/GREATEST (gh-4405)

  • Introduce WITH ENGINE clause for CREATE TABLE statement (gh-4422). To allow a user to specify engine as per table option, CREATE TABLE statement has been extended with optional WITH ENGINE = <engine_name> clause. This clause comes at the end of CREATE TABLE statement. For example:

    CREATE TABLE t_vinyl (id INT PRIMARY KEY) WITH ENGINE = 'vinyl';

    Refer also to SQL reference documentation.

  • Introduce DOUBLE type (gh-3812).

  • Display line and position in syntax errors (gh-2611).

  • Make constraint names unique within a table (gh-3503). The SQL standard requires PRIMARY KEY, UNIQUE, FOREIGN KEY and CHECK constraints to have the unique name within a table. Now Tarantool/SQL follows this requirement. Please refer to (doc-1053).

  • Optimization: a tuple already stores a map of offsets of indexed values. After the change, when a field after an indexed field is accessed, the tuple is decoded from the indexed field rather then from beginning (gh-4267).

Core

  • [Breaking change] Drop rows_per_wal option of box.cfg() in favor of wal_max_size (gh-3762).

  • Decimals can now be stored in spaces. The corresponding field type is introduced: decimal. Decimal values are also allowed in the scalar, any, and number fields. Decimal values can be indexed (gh-4333). Also refer to documentation on

  • Add support for decimals in update operations (gh-4413). tuple:update() and <space_object>:update() now support decimal operands for arithmetic operations (‘+’ and ‘-’). The syntax is as usual, for example:

    tarantool> d = box.tuple.new(decimal.new('1'))
---
...
tarantool> d:update{{'+', 1, decimal.new('0.5')}}
---
- [1.5]
...

    Insertion (‘!’) and assignment (‘=’) are also supported. See also the full description of the update() function in documentation.

  • Allow to encode/decode decimals to MsgPack and to encode to YAML and JSON. Part of (gh-4333); 485439e3; documentation: (doc-992).

  • Introduce field name and JSON path updates (gh-1261).

    Example of update by a field name: box.space.test:update({{'=', 'foo', 42}}).

    JSON path update allows to change a value that is nested inside an array or a map. It provides convenient syntax (that is also available for connectors), consumes less space in WAL than replace, and is faster than replaces written in Lua. Example: box.space.test:update({{'=', 'foo.bar[1]', 42}}). Please refer to documentation here: (doc-1051).

  • Introduce double field type. Part of (gh-3812). Though is not very usable in Lua, this new field type has been added in box as a base for the SQL DOUBLE type.

  • vinyl: don’t pin index for iterator lifetime (prerequisite for snapshot iterators). 02da82ea

  • vinyl: don’t exempt dropped indexes from dump and compaction (prerequisite for snapshot iterators). d7387ec9

Репликация

  • box.info().replication shows applier/replay’s latest error message. Now it also shows the errno description for system errors when it’s applicable (gh-4402).
  • Feed data from a memory during replica initial join (gh-1271). Aside of obvious speed up from reading from a memory instead of a disk, a read view that is acquired to perform an initial join may be a way more recent, that eliminates the need to play all xlog files since a last snapshot. Now relay need to send only changes that occur during initial join to finally join a replica.
  • Introduce a new replica type - anonymous replica (gh-3186). Anonymous replica is not present in cluster space and so there is no limitation for its count in a replica set. Anonymous replica is read-only, but can be deanonymized and enabled for writes. Please refer to documentation: (doc-1050) for API and details.

Lua

  • Expose require('tarantool').package which is ‘Tarantool’ for the community version and ‘Tarantool Enterprise’ for the enterprise version (gh-4408). This value is already displayed in a console greeting and in box.info().package, but it was not accessible from Lua before the first box.cfg{<...>} call.
  • decimal: add modulo operator (decimal.new(172.51) % 1 == 0.51), part of (gh-4403).
  • [Breaking change] JSON and msgpack serializers now raise an error when a depth of data nesting exceeds the encode_max_depth option value. The default value of the option has been increased from 32 to 128. The encode_deep_as_nil option is added to give an ability to set the old behaviour back (gh-4434). Notes:
    • These options can be set by using json.cfg({<...>}) or msgpack.cfg({<...>}).
    • box data modification functions (insert, replace, update and upsert) follow the options of the default msgpack serializer instance, and now these functions raise an error on too many levels of nested data by default rather than cut the data silently. This behaviour can be configured using msgpack.cfg({<...>}).
    • previously,box.tuple.new(), space:update(), space:upsert() and several other functions did not follow encode_max_depth option; now they do (see also the Bug fixed section).
    • previously,json.cfg and msgpack.cfg tables was not updated when an option had changed; now they show actual values (see also the Bug fixed section).
  • Show line and column in json.decode() errors (gh-3316).
  • Exit gracefully when a main script throws an error: notify systemd, log the error (gh-4382).
  • key_def: accept both field and fieldno in key_def.new(<...>) (gh-4519). Originally key_def.new(<...>) accepted only fieldno to allow creation with <index_object>.parts as argument. However, index definition format (<space_object>.create_index(<...>)) is different and requires field. Now both are supported.
  • Enable __pairs and __ipairs metamethods from Lua 5.2 (gh-4560). We still conform Lua 5.1 API that is not always compatible with Lua 5.2. The change is only about those metamethods.
  • Implement a new function fiber.top(). It returns a table with all fibers alive and lists their CPU consumption. For details, refer to documentation. (gh-2694)
  • Expose errno field for box.error objects representing system errors. Part of (gh-4402).

HTTP client

  • Add accept_encoding option for HTTP client. For details, refer to description here: (doc-1036). (gh-4232).
  • Add proxy server related options for HTTP client:
    • proxy
    • proxy_port
    • proxy_user_pwd
    • no_proxy For details, refer to description here: doc-896 (gh-4477, gh-4472).

Разное

  • tarantoolctl: allow to start instances with delayed box.cfg{} (gh-4435).
  • Add package builds and deployment for the following Linux distros:

Исправленные ошибки

SQL

  • Modify type of a binding value in query response metainformation: always return INTEGER rather than UNSIGNED, even for positive values. This is necessary for consistency with integer literal types. b7d595ac.
  • Reuse noSQL way to compare floating point values with integral ones. This allows to handle corner cases like SELECT 18446744073709551615.0 > 18446744073709551615 uniformly. 73a4a525.
  • Create or alter a table with a foreign key may lead to wrong bytecode generation that may cause a crash or wrong result (gh-4495).
  • Allow to update a scalar value using SQL in a space that was created from Lua and contains array, map or any fields (gh-4189). Note: Tarantool/SQL provides operations on scalar types and does not support ‘array’ and ‘map’ per se.
  • Allow nil to be returned from user-defined function (created with box.schema.func.create()). 1b39cbcf
  • Don’t drop a manually created sequence in DROP TABLE statement. a1155c8b
  • Remove grants associated with the table in DROP TABLE statement (gh-4546).
  • Fix segfault in sql_expr_coll() when SUBSTR() is called without arguments. 4c13972f
  • Fix converting of floating point values from range [2^63, 2^64] to integer (gh-4526).
  • Make type string case lower everywhere: in error messages, meta headers, and results of the typeof() SQL function. ee60d31d
  • Make theLENGTH() function to accept boolean argument (gh-4462).
  • Make implicit cast from BOOLEAN to TEXT to return uppercase for consistency with explicit cast (gh-4462).
  • Fix segfault on binding a value as LIKE argument (gh-4566).
  • For user-defined functions, verify that the returned value is of the type specified in the function definition (gh-4387).
  • Start using comprehensive serializer luaL_tofield() to prepare LUA arguments for user-defined functions. This allows to support cdata types returned from Lua function (gh-4387).
  • An error is raised when a user-defined function returns too many values (gh-4387).
  • Store a name of user-defined function in VDBE program instead of pointer. This allows to normally handle the situation when a user-defined function has been deleted to the moment of the VDBE code execution (gh-4176).
  • Fix casting of VARBINARY value to a NUMBER (gh-4356)
  • Print the data type instead of the data itself in diag_set() in case of binary data. The reason of this patch is that LibYAML converts the whole error message to base64 in case of non-printable symbols. Part of (gh-4356).
  • Remove ENGINE from the list of the reserved keywords and allow to use it for identifiers: we are going to use the word as a name of some fields for tables forming informational schema.
  • Fix segfault when LEAST() or GREATEST() built-in function is invoked without arguments (gh-4453).
  • Fix dirty memory access when constructing query plan involving search of floating point value in index over integer field (gh-4558).
  • INDEXED BY clause now obligates the query planner to choose provided index. 49fedfe3

Core

  • Make functional index creation transactional (gh-4401)
  • Detect a new invalid JSON path case (gh-4419)
  • Randomize the next checkpoint time after manual box.snapshot() execution also (gh-4432).
  • Fix memory leak in call/eval in case of a transaction is not committed (gh-4388)
  • Eliminate warning re strip_core option of box.cfg() on MacOS and FreeBSD (gh-4464)
  • The msgpack serializer that is under box.tuple.new() (called tuple serializer) now reflects options set by msgpack.cfg({<...>}). Part of (gh-4434). Aside of box.tuple.new() behaviour itself, it may affect tuple:frommap(), methods of key_def Lua module, tuple and table merger sources, net.box results of :select() and :execute() calls, and xlog Lua module.
  • box functions update and upsert now follow msgpack.cfg({encode_max_depth = <...>} option. Part of (gh-4434).
  • fiber: make sure the guard page is created; refuse to create a new fiber otherwise (gh-4541). It is possible in case of heavy memory usage, say, when there is no resources to split VMAs.
  • recovery: build secondary indices in the hot standby mode without waiting till the main instance termination (gh-4135).
  • Fix error message for incorrect return value of functional index extractor function (gh-4553).
    • Was: “Key format doesn’t match one defined in functional index ‘’ of space ‘’: supplied key type is invalid: expected boolean”
    • Now: “<…>: expected array”
  • JSON path index now consider is_nullable property when a space had a format (gh-4520).
  • Forbid 00000000-0000-0000-0000-000000000000 as the value of box.cfg({<...>}) options: replicaset_uuid and instance_uuid (gh-4282). It did not work as expected: the nil UUID was treated as absence of the value.
  • Update cache of universe privileges without reconnect (gh-2763).
  • net.box: fix memory leak in net_box:connect(<URI>) (gh-4588).
  • net.box: don’t fire the on_connect trigger on schema update (gh-4593). Also don’t fire the on_disconnect trigger if a connection never entered into the active state (e.g. when the first schema fetch is failed).
  • func: fix use-after-free on function unload. fa2893ea
  • Don’t destroy a session until box.session.on_disconnect(<...>) triggers are finished (gh-4627). This means, for example, that box.session.id() can be safely invoked from the on_disconnect trigger. Before this change box.session.id() returned garbage (usually 0) after yield in the on_disconnect trigger. Note: tarantool/queue module is affected by this problem in some scenarios. It is especially suggested to update Tarantool at least to this release if you’re using this module.
  • func: Fix box.schema.func.drop(<..>) to unload unused modules (gh-4648). Also fix box.schema.func.create(<..>) to avoid loading a module again when another function from the module is loaded.
  • Encode Lua number -2^63 as integer in msgpack.encode() and box’s functions (gh-4672).
  • Forbid to drop admin’s universe access. 2de398ff. Bootstrap and recovery work on behalf of admin and should be able to fill in the system spaces. Drop of admin’s access may lead to an unrecoverable cluster.
  • Refactor rope library to eliminate virtual calls to increase performance of the library (mainly for JSON path updates). baa4659c
  • Refactor update operation code to avoid extra region-related arguments to take some performance boost (mainly for JSON path updates). dba9dba7
  • Error logging has been removed in engine_find() to get rid of the error message duplication. 35177fe0.
  • decimal: Fix encoding of numbers with positive exponent. Follow-up (gh-692).
  • Increment schema version on DDL operations where it did not performed before: alter of trigger, check constraint and foreign key constraint. Part of (gh-2592).

Репликация

  • Stop relay on subscribe error (gh-4399).
  • Set last_row_time to now in relay_new and relay_start (gh-4431).
  • Do not abort replication on ER_UNKNOWN_REPLICA (gh-4455).
  • Enter orphan mode on manual replication configuration change (gh-4424).
  • Disallow bootstrap of read-only masters (gh-4321).
  • Prefer to bootstrap a replica from a fully bootstrapped instance rather than from an instance that is in the process of bootstrapping (gh-4527). This change enables the case when two nodes (B, C) are being bootstrapped simultaneously using the one that is already bootstrapped (A), while A is configured to replicate from {B, C} and B – from {A, C}.
  • Return immediately from box.cfg{<...>} when an instance is reconfigured with replication_connect_quorum = 0 (gh-3760). This change also fixes the behaviour of reconfiguration with non-zero replication_connect_quorum: box.cfg{<...>} returns immediately regardless of whether connections to upstreams are established.
  • Apply replication settings of box.cfg({<...>}) in a strict order (gh-4433).
  • Auto reconnect a replica if password is invalid (gh-4550).
  • box.session.su(<username>) now correctly reports an error for <username> longer than BOX_NAME_MAX which is 65000. 8b6bdb43
    • Was: ‘C++ exception’
    • Now: ‘name length <…> is greater than BOX_NAME_MAX’
  • Use empty password when a URI in box.cfg{replication = <...>} is like login@host:port (gh-4605). The behaviour matches the net.box’s one now. Explicit login:@host:port was necessary before, otherwise a replica displayed the following error: > Missing mandatory field ‘tuple’ in request
  • Fix segfault during replication configuration (box.cfg{replication = <...>} call) (gh-4440, gh-4576, gh-4586, gh-4643).
  • Cancel a replica joining thread forcefully on Tarantool instance exit (gh-4528).
  • Fix the applier to run the <space>.before_replace trigger during initial join (gh-4417).

Lua

  • Fix segfault on ffi.C._say() without filename (gh-4336).
  • Fix pwd.getpwall() and pwd.getgrall() hang on CentOS 6 and FreeBSD 12 (gh-4428, gh-4447).
  • json.encode() now follows encode_max_depth option for arrays that leads to a segfault on recursive Lua tables with numeric keys (gh-4366).
  • fio.mktree() now reports an error for existing non-directory file (gh-4439).
  • json.cfg and msgpack.cfg tables were not updated when an option is changed. Part of (gh-4434).
  • Fix handling of a socket read error in the console client (console.connect(<URI>) or tarantoolctl connect/enter <...>). 89ec1d97
  • Handle the “not enough memory” error gracefully when it is raised from lua_newthread() (gh-4556). There are several cases when a new Lua thread is created:
    • Start executing a Lua function call or an eval request (from a binary protocol, SQL or with box.func.<...>:call()).
    • Create of a new fiber.
    • Start execution of a trigger.
    • Start of encoding into a YAML format (yaml.encode()).
  • Fix stack-use-after-scope in json.decode() (gh-4637).
  • Allow to register several functions using box.schema.func.create(), whose names are different only in letters case (gh-4561). This make function names work consistently with other names in tarantool (except SQL, of course).
  • Fix decimal comparison with nil. Follow-up (gh-692).
  • Fix decimal comparison with box.NULL (gh-4454).
  • A pointer returned by msgpack.decode*(cdata<[char] const *>) functions can be assigned to buffer.rpos now (and the same for msgpackffi) (gh-3926). All those functions now return cdata<char *> or cdata<const char *> depending of a passed argument. Example of the code that did not work: res, buf.rpos = msgpack.decode(buf.rpos, buf:size()).
  • lua/pickle: fix typo that leads to reject of negative integers for ‘i’ (integer) and ‘N’ (big-endian integer) formats in pickle.pack(). e2d9f664

HTTP client

  • Use bundled libcurl rather than system-wide by default. (gh-4318, gh-4180, gh-4288, gh-4389, gh-4397). This closes several known problems that were fixed in recent libcurl versions, including segfaults, hangs, memory leaks and performance problems.
  • Fix assertion fail after a curl write error (gh-4232).
  • Disable verbose mode when {verbose = false} is passed. 72613bb0

Console Lua output

A new Lua output format is still in the alpha stage and has the known flaws, but we are working to make it rich and stable.

  • Output box.NULL as "box.NULL" rather than "cdata<void *>: NULL", part of (gh-3834) (in quotes for now, yes, due to (gh-4585)
  • Add semicolon (;) as responses delimiter (EOS, end of stream/statement), analogue of YAMLs end-of-document (...) marker. This is vital for remote clients to determine the end of a particular response, part of (gh-3834).
  • Fix hang in the console client (console.connect(<URI>) or tarantoolctl connect/enter <...>) after \set output lua[,block] command, part of (gh-3834). In order to overcome it, two changes have been made:
    • Parse \set output lua[,block] command on a client prior to sending it to a server, store current responses delimiter (EOS) and use it to determine end of responses.
    • Send \set output <...> command with a default output mode when establishing a connection (it is matter if different default modes are set).
  • Provide an ability to get or set current responses delimiter using console.eos([<...>]), part of (gh-3834).

LuaJIT

  • Fix fold machinery misbehaves (gh-4376).
  • Fix for debug.getinfo(1,'>S') (gh-3833).
  • Fix string.find recording (gh-4476).
  • Fix the “Data segment size exceeds process limit” error on FreeBSD/x64: do not change resource limits when it is not necessary (gh-4537).
  • fold: keep type of emitted CONV in sync with its mode. LuaJIT#524 This fixes the following assertion fail: > asm_conv: Assertion `((IRType)((ir->t).irt & IRT_TYPE)) != st’ failed

Разное

  • Support systemd’s NOTIFY_SOCKET on OS X (gh-4436).
  • Fix linking with static openssl library (gh-4437).
  • Get rid of warning re empty NOTIFY_SOCKET variable (gh-4305).
  • rocks: fix ‘invalid date format’ error when installing a packed rock (gh-4481).
  • Remove libyaml from rpm/deb dependencies, because we use bunbled version of libyaml for the packages (since 2.2.1) (gh-4442).
  • Fix CLI boolean options handling in tarantoolctl cat <...>, such as --show-system (gh-4076).
  • Fix segfault (out of bounds access) when a stack unwinding error occurs at backtrace printing (gh-4636). Backtrace is printed on the SIGFPE and SIGSEGV signals or when LuaJIT finds itself in the unrecoverable state (lua_atpanic()).
  • Clear terminal state on panic (gh-4466).
  • access: fix the invalid error type box.session.su() raises for a not found user
    • was: SystemError
    • now: ClientError

Building from sources

  • Fix for GCC 4.8.5, which is default version on CentOS 7 (gh-4438).
  • Fix OpenSSL linking problems on FreeBSD (gh-4490).
  • Fix linking problems on Mac OS when several toolchains are in PATH (gh-4587).
  • Fix GCC 9 warning on strncpy() (gh-4515).
  • Fix build on Mac with gcc and XCode 11 (gh-4580).
  • Fix LTO warnings that were treated as errors in a release build (gh-4512).

Tarantool 2.2.3

Release: v. 2.2.3 Date: 2020-04-20 Tag: 2.2.3-1-g98ecc90

Общие сведения

2.2.3 is the last stable version of the 2.2 release series. The label stable means we have all planned features implemented and we see no high-impact issues.

This release resolves roughly 34 issues since the latest stable version. There may be bugs in less common areas, please feel free to file an issue at GitHub.

Please note, this release contains no new features.

Совместимость

Tarantool 2.x is backward compatible with Tarantool 1.10.x in binary data layout, client-server protocol and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Исправленные ошибки

Core

  • fiber.storage is cleaned between requests, and can be used as a request-local storage. Previously fiber.storage could contain some old values in the beginning of an iproto request execution, and it needed to be nullified manually. Now the cleanup is unneeded (gh-4662).
  • tuple/space/index:update()/upsert() were fixed not to turn a value into an infinity when a float value was added to or subtracted from a float column and exceeded the float value range (gh-4701).
  • Fix potential execution abort when operating the system runs under heavy memory load (gh-4722).
  • Make RTREE indexes handle the out of memory error: before this fix, OOM during the recovery of an RTREE index resulted in segmentation fault (gh-4619).
  • Fix the error message returned on using an already dropped sequence (gh-4753).
  • Add cancellation guard to avoid WAL thread stuck (gh-4127).
  • Fix execution abort when memtx_memory and vinyl_memory are set to more than 4398046510080 bytes. Now an error message is returned (gh-4705).

Репликация

  • Fix rebootstrap procedure not working in case replica itself is listed in box.cfg.replication (gh-4759).
  • Fix possible user password leaking via replication logs (gh-4493).
  • Refactor vclock map to be exactly 4 bytes in size to fit all 32 replicas regardless of the compiler used (https://github.com/tarantool/tarantool/commit/e5679980aa5f813553a95ab7d31f111dd0893df6).
  • Fix crash when the replication applier rollbacks a transaction (gh-4730, (gh-4776).
  • Local space operations are now counted in 0th vclock component. Every instance may have its own 0-th vclock component not matching others’. Local space operations are not replicated at all, even as NOPs (gh-4114).
  • Gc consumers are now ordered by their vclocks and not by vclock signatures. Only the WALS that contain no entries needed by any of the consumers are deleted (gh-4114).

Lua

  • json: :decode() doesn’t spoil instance’s options with per-call ones (when it is called with the second argument) (gh-4761).
  • Handle empty input for uri.format() properly (gh-4779).
  • os.environ() is now changed when os.setenv() is called (gh-4733).
  • netbox.self:call/eval() now returns the same types as netbox_connection:call/eval. Previously it could return a tuple or box.error cdata (gh-4513).
  • box.tuple.* namespace is cleaned up from private functions. box.tuple.is() description is added to documentation (gh-4684).
  • tarantoolctl rocks search: fix the --all flag (gh-4529).
  • tarantoolctl rocks remove: fix the --force flag (gh-3632).
  • libev: backport fix for listening for more then 1024 file descriptors on Mac OS (gh-3867).

SQL

  • Fix box.stat() behavior: now it collects statistics on the PREPARE and EXECUTE methods as expected (gh-4756).
  • The inserted values are inserted in the order in which they are given in case of INSERT into space with autoincrement (gh-4256).

HTTP client

  • When building Tarantool with bundled libcurl, link it with the c-ares library by default (gh-4591).

LuaJIT

  • __pairs/__ipairs metamethods handling is removed since we faced the issues with the backward compatibility between Lua 5.1 and Lua 5.2 within Tarantool modules as well as other third party code (gh-4770).
  • Introduce luajit-gdb.py extension with commands for inspecting LuaJIT internals. The extension obliges one to provide gdbinfo for libluajit, otherwise loading fails. The extension provides the following commands:
    • lj-arch dumps values of LJ_64 and LJ_GC64 macro definitions
    • lj-tv dumps the type and GCobj info related to the given TValue
    • lj-str dumps the contents of the given GCstr
    • lj-tab dumps the contents of the given GCtab
    • lj-stack dumps Lua stack of the given lua_State
    • lj-state shows current VM, GC and JIT states
    • lj-gc shows current GC stats
  • Fix string to number conversion: current implementation respects the buffer length (gh-4773).
  • “FFI sandwich”(*) detection is introduced. If sandwich is detected
    while trace recording the recording is aborted. The sandwich detected while mcode execution leads to the platform panic.
  • luaJIT_setmode call is prohibited while mcode execution and leads to the platform panic.

(*) The following stack mix is called FFI sandwich:

Lua-FFI -> C routine -> Lua-C API -> Lua VM

This sort of re-entrancy is explicitly not supported by LuaJIT compiler. For more info see gh-4427.

Vinyl

  • Fix assertion fault due to triggered dump process during secondary index build (gh-4810).

Разное

  • Fix crashes at attempts to use -e and -l command line options concatenated with their values, like this: -eprint(100) (gh-4775).
  • Fix inability to upgrade from 2.1 if there was an automatically generated sequence (gh-4771).
  • Update libopenssl version to 1.1.1f since the previous one was EOLed (gh-4830).

Building from sources

Tarantool 2.2.2

Release: v. 2.2.2 Date: 2019-12-31 Tag: 2.2.2-0-g0a577ff

Общие сведения

2.2.2 is the first stable version of the 2.2 release series. The label stable means we have all planned features implemented and we see no high-impact issues.

This release resolves roughly 75 issues since the latest beta version. There may be bugs in less common areas, please feel free to file an issue at GitHub.

Совместимость

Tarantool 2.x is backward compatible with Tarantool 1.10.x in binary data layout, client-server protocol and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 2.x series.

Изменения или добавления функциональности

There are changes labeled with [Breaking change]. It means that the old behaviour was considered error-prone and therefore changed to protect users from unintended mistakes. However, there is a little probability that someone can lean on the old behaviour, and this label is to bring attention to the things that have been changed.

Core

  • [Breaking change] Drop rows_per_wal box.cfg() option in favor of wal_max_size (gh-3762)

Lua

  • [Breaking change] json and msgpack serializers now raise an error when a depth of data nesting exceeds encode_max_depth option value. The default value of the option is increased from 32 to 128. encode_deep_as_nil option was added to give ability to set the old behaviour back (gh-4434). Note: Those options can be set using json.cfg({<...>}) or msgpack.cfg({<...>}). Note: box data modification functions (insert, replace, update, upsert) follows options of default msgpack serializer instance and now they will raise an error by default on too nested data rather then cut them silently. This behaviour can be configured using msgpack.cfg({<...>}). Note: box.tuple.new(), space:update(), space:upsert() and several other functions did not follow encode_max_depth option, now they do (see also ‘Bug fixes’). Note: json.cfg and msgpack.cfg tables did not updated when an option is changed, now they show actual values (see also ‘Bug fixes’).
  • Show line and column in json.decode() errors (gh-3316)
  • Exit gracefully when a main script throws an error: notify systemd, log the error (gh-4382)
  • key_def: accept both field and fieldno in key_def.new(<...>) (gh-4519). Originally key_def.new(<...>) accepts only fieldno to allow creation with <index_object>.parts as argument. However index definition format (<space_object>.create_index(<...>)) is different and requires field. Now both are supported.
  • Enable __pairs and __ipairs metamethods from Lua 5.2 (gh-4560). We still conform Lua 5.1 API, which is not always compatible with Lua 5.2. The change is only about those metamethods.

Разное

  • tarantoolctl: allow to start instances with delayed box.cfg{} (gh-4435)
  • Add package builds and deployment for the following Linux distros:

Исправленные ошибки

SQL

  • Modify type of a binding value in a query response metainformation: always return INTEGER rather then UNSIGNED, even for positive values. This is necessary for consistency with integer literal types. c5246686.
  • Reuse noSQL way to compare floating point values with integral ones. This allows to handle corner cases like SELECT 18446744073709551615.0 > 18446744073709551615 uniformly. 12431ed4.
  • Create or alter of a table with a foreign key may lead to wrong bytecode generation that may cause a crash or wrong result (gh-4495)
  • Allow to update a scalar value using SQL in a space that was created from Lua and contains ‘array’, ‘map’ or ‘any’ field (gh-4189). Note: Tarantool/SQL provides operations on scalar types and does not support ‘array’ and ‘map’ per se.
  • INDEXED BY clause now obligates the query planner to choose provided index, 411be0f0
  • Fix dirty memory access when constructing query plan involving search of floating point value in index over integer field (gh-4558)

Core

  • Detect a new invalid json path case (gh-4419)
  • Randomize the next checkpoint time also after a manual box.snapshot() (gh-4432)
  • Fix memory leak in call / eval in the case when a transaction is not committed (gh-4388)
  • Eliminate warning re ‘strip_core’ box.cfg option on MacOS and FreeBSD (gh-4464)
  • The msgpack serializer that is under box.tuple.new() (called tuple serializer) did not reflect options set by msgpack.cfg({<...>}), part of (gh-4434). Aside of box.tuple.new() behaviour itself, it may affect tuple:frommap(), methods of key_def Lua module, tuple and table merger sources, net.box results of :select() and :execute() calls, xlog Lua module.
  • box’s update and upsert now follow msgpack.cfg({encode_max_depth = <...>} option, part of (gh-4434)
  • fiber: make sure the guard page is created, refuse to create a new fiber otherwise (gh-4541). It is possible in case of heavy memory pressure, say, when there is no resources to split VMAs.
  • recovery: build secondary indices in the hot standby mode without waiting till the main instance termination (gh-4135)
  • Fix error message for incorrect return value of functional index extractor function (gh-4553)
    • Was: «Key format doesn’t match one defined in functional index ‘’ of space ‘’: supplied key type is invalid: expected boolean’
    • Now: “<…>: expected array”
  • JSON path index did ignore is_nullable property when a space had a format (gh-4520)
  • Forbid 00000000-0000-0000-0000-000000000000 as replicaset_uuid and instance_uuid box.cfg({<...>}) options value, (gh-4282). It did not work as expected: the nil UUID was treated as absence of a value.
  • Update cache of universe privileges without reconnect (gh-2763)
  • net.box: fix memory leak in net_box:connect(<URI>) (gh-4588)
  • net.box: don’t fire on_connect trigger at schema update (gh-4593). Also don’t fire on_disconnect trigger if a connection never entered into ‘active’ state (e.g. when a first schema fetch is failed).
  • func: fix use after free on function unload, 64f4d06a
  • Fix bootstrap.snap file in order to overcome the following warning, (gh-4510) > xlog.c:1934 E> can’t open tx: bootstrap: has some data after eof marker at 5902
  • Don’t destroy a session until box.session.on_disconnect(<...>) triggers will be finished (gh-4627). This means that, say, box.session.id() can be safely invoked from the on_disconnect trigger. Before this change box.session.id() returns garbage (usually 0) after yield in the on_disconnect trigger. Note: tarantool/queue module is affected by this problem in some scenarious. It is especially suggested to update tarantool at least to this release if you’re using this module.
  • func: box.schema.func.drop(<..>) did not unload unused modules (gh-4648). Also box.schema.func.create(<..>) did load of a module again even when another function from the module is loaded.
  • Encode Lua number -2^63 as integer in msgpack.encode() and box’s functions (gh-4672)

Репликация

  • Stop relay on subscribe error (gh-4399)
  • Set last_row_time to now in relay_new and relay_start (gh-4431)
  • Do not abort replication on ER_UNKNOWN_REPLICA (gh-4455)
  • Enter orphan mode on manual replication configuration change (gh-4424)
  • Disallow bootstrap of read-only masters (gh-4321)
  • Prefer to bootstrap a replica from a fully bootstrapped instance rather than currently bootstrapping one (gh-4527). This change enables the case when two nodes (B, C) are being bootstrapped simultaneously using the one that is already bootstrapped (A), while A is configured to replicate from {B, C} and B from {A, C}.
  • Return immediately from box.cfg{<...>} when an instance is reconfigured with replication_connect_quorum = 0 (gh-3760) This change also fixes the behaviour of reconfiguration with non-zero replication_connect_quorum: box.cfg{<...>} returns immediately regardless of whether connections to upstreams are established.
  • Apply replication box.cfg({<...>}) settings in a strict order (gh-4433)
  • Auto reconnect a replica if password is invalid (gh-4550)
  • box.session.su(<username>) now reports an error correctly for <username> longer then BOX_NAME_MAX, which is 65000, 43e29191 Was: ‘C++ exception’ Now: ‘name length <…> is greater than BOX_NAME_MAX’
  • Use empty password when an URI in box.cfg{replication = <...>} is like login@host:port (gh-4605). The behaviour match net.box’s one now. Explicit login:@host:port was necessary before, otherwise a replica shows the following error: > Missing mandatory field ‘tuple’ in request
  • Fix segfault during replication configuration (box.cfg{replication = <...>} call) (gh-4440, gh-4576, gh-4586, gh-4643)

Lua

  • Fix segfault on ffi.C._say() without filename (gh-4336)
  • Fix pwd.getpwall() and pwd.getgrall() hang on CentOS 6 and FreeBSD 12 (gh-4428, gh-4447)
  • json.encode() now follows encode_max_depth option for arrays that leads to a segfault on recursive Lua tables with numeric keys (gh-4366)
  • fio.mktree() now reports an error for existing non-directory file (gh-4439)
  • Update json.cfg and msgpack.cfg tables when an option is changed, part of (gh-4434)
  • Fix handling of a socket read error on the console client (console.connect(<URI>) or tarantoolctl connect/enter <...>), b0b19992
  • Handle ‘not enough memory’ gracefully when it is raised from lua_newthread() (gh-4556). There are several places where a new Lua thread is created:
    • Start execution a Lua function call or an eval request (from a binary protocol, SQL or with box.func.<...>:call()).
    • Create of a new fiber.
    • Start execution of a trigger.
    • Start of encoding into a YAML format (yaml.encode()).
  • Fix stack-use-after-scope in json.decode() (gh-4637)

HTTP client

  • Use bundled libcurl rather than system-wide by default, (gh-4318, gh-4180, gh-4288, gh-4389, gh-4397). This closes several known problems that were fixed in recent libcurl versions, including segfaults, hangs, memory leaks and performance problems.
  • Disable verbose mode when {verbose = false} is passed, 5f3d9015
  • Fix assertion fail after curl write error (gh-4232)

Console Lua output

The new Lua output format is still in the alpha stage and has known flaws, but we are working to make it rich and stable.

  • Output box.NULL as "box.NULL" rather then "cdata<void *>: NULL", part of (gh-3834) (in quotes for now, yes, due to (gh-4585)
  • Add semicolon (;) as responses delimiter (EOS, end of stream/statement), analogue of YAMLs end-of-document (...) marker. This is vital for remote clients to determine an end of a particular response, part of (gh-3834).
  • Fix hang in the console client (console.connect(<URI>) or tarantoolctl connect/enter <...>) after \set output lua[,block] command, part of (gh-3834). In order to overcome it two changes were made:
    • Parse \set output lua[,block] command on a client prior to sending it to a server, store current responses delimiter (EOS) and use it to determine end of responses.
    • Send \set output <...> command with a default output mode when establishing a connection (it is matter if different default modes are set).
  • Provide ability to get or set current responses delimiter using console.eos([<...>]), part of (gh-3834)

LuaJIT

  • Fix fold machinery misbehaves (gh-4376)
  • Fix for debug.getinfo(1,'>S') (gh-3833)
  • Fix string.find recording (gh-4476)
  • Fixed ‘Data segment size exceeds process limit’ error on FreeBSD/x64: do not change resource limits when it is not necessary (gh-4537)
  • fold: keep type of emitted CONV in sync with its mode, LuaJIT#524 This fixes the following assertion fail: > asm_conv: Assertion `((IRType)((ir->t).irt & IRT_TYPE)) != st’ failed

Разное

  • Support systemd’s NOTIFY_SOCKET on OS X (gh-4436)
  • Fix linking with static openssl library (gh-4437)
  • Get rid of warning re empty NOTIFY_SOCKET variable (gh-4305)
  • rocks: fix ‘invalid date format’ error when installing a packed rock (gh-4481)
  • Remove libyaml from rpm/deb dependencies, because we use bunbled version of libyaml for the packages (since 2.2.1) (gh-4442)
  • Fix boolean CLI options handling in tarantoolctl cat <...>, such as --show-system (gh-4076)
  • Fix segfault (out of bounds access) when unwinding error occurs at backtrace printing (gh-4636). Backtrace is printed on SIGFPE and SIGSEGV signal or when LuaJIT find itself in unrecoverable state (lua_atpanic()).

Building from sources

  • Fix for GCC 4.8.5, which is default version on CentOS 7 (gh-4438)
  • Fix OpenSSL linking problems on FreeBSD (gh-4490)
  • Fix linking problems on Mac OS when several toolchains are in PATH (gh-4587)
  • Fix GCC 9 warning on strncpy() (gh-4515)

Tarantool 2.2.1

Release: v. 2.2.1. Release type: beta. Release date: 2019-08-02.

Overview

This is a beta version of the 2.2 series. The label «beta» means we have no critical issues and all planned features are there.

The goal of this release is to introduce new indexing features, extend SQL feature set, and improve integration with the core.

Compatibility

Tarantool 2.x обратно совместим с Tarantool 1.10.x в том, что касается структуры бинарных данных, клиент-серверного протокола и протокола репликации. Обновление можно произвести с помощью процедуры box.schema.upgrade().

Functionality added or changed

Tarantool 2.1.2 and earlier

Release: https://github.com/tarantool/tarantool/releases

Версия 2.1.2

Release type: stable. Release date: 2019-04-05.

Release: v. 2.1.2.

This is the first stable release in the 2.x series.

The goal of this release is to significantly extend SQL support and increase stability.

Изменения или добавления функциональности:

Версия 2.1.1

Release type: beta. Release date: 2018-11-14.

Release: v. 2.1.1.

This release resolves all major bugs since 2.0.4 alpha and extends Tarantool’s SQL feature set.

Версия 2.0.4

Тип версии: альфа. Дата выхода: 2018-02-15.

Release: v. 2.0.4.

This is a successor of the 1.8.x releases. It improves the overall stability of the SQL engine and has some new features.

Изменения или добавления функциональности:

  • Added support for SQL collations by incorporating libICU character set and collation library.
  • IPROTO interface was extended to support SQL queries.
  • net.box subsystem was extended to support SQL queries.
  • Enabled ANALYZE statement to produce correct results, necessary for efficient query plans.
  • Enabled savepoints functionality. SAVEPOINT statement works w/o issues.
  • Enabled ALTER TABLE ... RENAME statement.
  • Improved rules for identifier names: now fully consistent with Lua frontend.
  • Enabled support for triggers; trigger bodies now persist in Tarantool snapshots and survive server restart.
  • Significant performance improvements.

Tarantool 1.10.15

Released on 2023-02-20.

Overview

1.10.15 is the next stable release in the long-term support (LTS) version 1.10.x release series.

The label “stable” means there are 1.10.x-based applications running in production for quite a while without known crashes, incorrect results or other showstopper bugs.

This release introduces 2 improvements and resolves roughly 8 issues since the 1.10.14 version.

Compatibility

Tarantool 1.10.x is backward compatible with Tarantool 1.9.x in binary data layout, client-server protocol and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 1.10.x series.

Functionality added or changed

Build

  • OpenSUSE 15.1 and 15.2 are no longer supported.
  • Updated libcurl to version 7.87.0 (gh-8150).

Bugs fixed

Core

  • Fixed a bug when fields could be removed from a table stored in a variable when a logging function was called on this variable (for example, log.info(a)) (gh-3853).
  • Fixed a logging bug: when logging tables with fields that have reserved internal names (such as pid) in the plain log format, such fields weren’t logged (gh-3853).
  • Added the message field when logging tables without such field in the JSON log format (gh-3853).
  • Fixed an assertion on malformed JSON message written to the log (gh-7955).

Vinyl

  • Fixed a bug that could result in select() skipping an existing tuple after a rolled back delete() (gh-7947).

LuaJIT

Backported patches from vanilla LuaJIT trunk (gh-7230). In the scope of this activity, the following issues have been resolved:

  • Fix overflow check in unpack() optimized by a compiler.
  • Fix recording of tonumber() with cdata argument for failed conversions (gh-7655).
  • Fix concatenation operation on cdata. It always raises an error now.
  • Fix io.close() for already closed standard output.
  • Fix trace execution and stitching inside vmevent handler (gh-6782).
  • Fixed emit_loadi() on x86/x64 emitting xor between condition check and jump instructions.
  • Fix stack top for error message when raising the OOM error (gh-3840).
  • Disabled math.modf compilation due to its rare usage and difficulties with proper implementation of the corresponding JIT machinery.
  • Fixed inconsistent behaviour on signed zeros for JIT-compiled unary minus (gh-6976).
  • Fixed IR_HREF hash calculations for non-string GC objects for GC64.
  • Fixed assembling of type-check-only variant of IR_SLOAD.
  • Fixed the Lua stack dump command (lj-stack) not working on Python 2. Previously, it used arguments unpacking within the list initialization, which is not supported in Python 2 (gh-7458).

Backported patches from vanilla LuaJIT trunk (gh-8069). In the scope of this activity, the following issues have been resolved:

  • Fixed loop realigment for dual-number mode
  • Fixed os.date() for wider libc strftime() compatibility.

Fiber

  • Fixed the assertion fail in cord_on_yield (gh-6647).

Log

  • Fixed an incorrect facility value in syslog on Alpine (gh-8269).

Build

  • Fixed -Werror build fail on Clang 15 (gh-8110).

Tarantool 1.10.14

Released on 2022-08-08.

Overview

1.10.14 is the next stable release in the long-term support (LTS) version 1.10.x release series.

The label “stable” means there are 1.10.x-based applications running in production for quite a while without known crashes, incorrect results or other showstopper bugs.

This release introduces 10 improvements and resolves roughly 20 issues since the 1.10.13 version.

Compatibility

Tarantool 1.10.x is backward compatible with Tarantool 1.9.x in binary data layout, client-server protocol and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 1.10.x series.

Functionality added or changed

Build

  • Fedora 35 is now supported (gh-6692).
  • Fedora 36 is now supported.
  • Ubuntu 22.04 (Jammy Jellyfish) is now supported.
  • Fedora 30, 31, 32, and 33 are no longer supported.
  • Ubuntu 21.04 (Hirsute Hippo) is no longer supported.
  • Updated OpenSSL used for static builds to version 1.1.1n (gh-6947).
  • Updated OpenSSL used for static builds to version 1.1.1q.
  • Updated libcurl to version 7.83.0 (gh-6029).
  • Updated libcurl to version 7.84.0.
  • Updated libyaml to the version with fixed stack overflows.

Bugs fixed

Core

  • Fixed a memory leak in the interactive console (gh-6817).
  • Fixed an assertion fail when passing a tuple without the primary key fields to a before_replace trigger. Now the tuple format is checked before the execution of before_replace triggers and after each of them (gh-6780).
  • Now inserting a tuple with a wrong id field into the \_priv space returns the correct error (gh-6295).
  • Fixed a bug that was making all fibers created with fiber_attr_setstacksize() leak until the thread exit. Their stacks also leaked except when fiber_set_joinable(..., true) was used.
  • Fixed a crash that happened when Tarantool was launched with multiple -e or -l options without spaces between the options and their values (gh-5747).
  • Fixed the usage of box.session.peer() in box.session.on_disconnect() triggers. Now it’s safe to assume that box.session.peer() returns the address of the disconnected peer, not nil, as it used to (gh-7014).
  • Fixed a bug in the sequence cache that could result in an error creating a new sequence (gh-5306).

Vinyl

  • Immediate removal of compacted run files created after the last checkpoint optimization now works for the initial JOIN stage of a replica (gh-6568).
  • Fixed a crash during the recovery of a secondary index in case the primary index contains incompatible phantom tuples (gh-6778).
  • Fixed a bug in the vinyl upsert squashing optimization that could lead to a segmentation fault error (gh-5080).
  • Fixed a bug in the vinyl read iterator that could result in a significant performance degradation of range select requests in the presence of an intensive write workload (gh-5700).

Replication

  • Fixed replicas failing to bootstrap when the master has just restarted (gh-6966).

LuaJIT

  • Fixed the top part of Lua stack (red zone, free slots, top slot) unwinding in the lj-stack command.
  • Added the value of g->gc.mmudata field to lj-gc output.
  • Fixed a bug with string.char() builtin recording when no arguments are provided (gh-6371, gh-6548).
  • Actually made JIT respect the maxirconst trace limit while recording (gh-6548).
  • Backported patches from vanilla LuaJIT trunk (gh-6548, gh-7230). In the scope of this activity, the following issues have been resolved:
    • Fixed emitting for fuse load of constant in GC64 mode (gh-4095, gh-4199, gh-4614).
    • Now initialization of zero-filled struct is compiled (gh-4630, gh-5885).
    • Actually implemented maxirconst option for tuning JIT compiler.
    • Fixed JIT stack of Lua slots overflow during recording for metamethod calls.
    • Fixed bytecode dump unpatching for JLOOP in up-recursion compiled functions.
    • Fixed FOLD rule for strength reduction of widening in cdata indexing.
    • Fixed string.char() recording without arguments.
    • Fixed print() behaviour with the reloaded default metatable for numbers.
    • tonumber("-0") now saves the sign of number for conversion.
    • tonumber() now gives predictable results for negative non-base-10 numbers.
    • Fixed write barrier for debug.setupvalue() and lua_setupvalue().
    • jit.p now flushes and closes output file after run, not at program exit.
    • Fixed jit.p profiler interaction with GC finalizers.
    • Fixed the case for partial recording of vararg function body with the fixed number of result values in with LJ_GC64 (i.e. LJ_FR2 enabled) (gh-7172).
    • Fixed handling of errors during trace snapshot restore.

Box

  • Added the check of the iterator type in the select, count, and pairs methods of the index object. Iterator can now be passed to these methods directly: box.index.ALL, box.index.GT, and so on (gh-6501).

Recovery

  • With the force_recovery cfg option, Tarantool is now able to boot from snap/xlog combinations where xlog covers changes committed both before and after the snap was created. For example, 0...0.xlog that covers everything up to vclock {1: 15} and 0...09.snap corresponding to vclock {1: 9} (gh-6794).

Tarantool 1.10.13

Released on 2022-04-25.

Overview

1.10.13 is the next stable release in the long-term support (LTS) version 1.10.x release series.

The label “stable” means there are 1.10.x-based applications running in production for quite a while without known crashes, incorrect results or other showstopper bugs.

This release introduces 1 improvement and resolves roughly 13 issues since the 1.10.12 version.

Compatibility

Tarantool 1.10.x is backward compatible with Tarantool 1.9.x in binary data layout, client-server protocol and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 1.10.x series.

Functionality added or changed

Build

  • Support fedora-35 build (gh-6692).

Bugs fixed

Core

  • Fixed memory leak in interactive console (gh-6817).
  • Fixed an assertion fail when passing tuple without primary key fields to before_replace trigger. Now tuple format is checked before the execution of before_replace triggers and after each one (gh-6780).
  • Now inserting a tuple with the wrong id field into the _priv space returns the correct error (gh-6295).
  • Fixed a bug due to which all fibers created with fiber_attr_setstacksize() leaked until the thread exit. Their stacks also leaked except when fiber_set_joinable(..., true) was used.
  • Fixed a crash when Tarantool was launched with multiple -e or -l options without a space between the option and the value (gh-5747).

Vinyl

  • Immediate removal of compacted run files created after the last checkpoint optimization now works for replica’s initial JOIN stage (gh-6568).
  • Fixed crash during recovery of a secondary index in case the primary index contains incompatible phantom tuples (gh-6778).

Replication

  • Fixed replicas failing to bootstrap when master is just re-started (gh-6966).

LuaJIT

  • Fixed top part of Lua stack (red zone, free slots, top slot) unwinding in lj-stack command.
  • Added the value of g->gc.mmudata field to lj-gc output.
  • string.char() builtin recording is fixed in case when no arguments are given (gh-6371, gh-6548).
  • Actually made JIT respect maxirconst trace limit while recording (gh-6548).

Box

  • Added iterator type checking and allow passing iterator as a box.index.{ALL,GT,…} directly (gh-6501).

Recovery

  • When force_recovery cfg option is set, Tarantool is able to boot from snap/xlog combinations where xlog covers changes committed both before and after snap creation. For example, 0...0.xlog, covering everything up to vclock {1: 15} and 0...09.snap, corresponding to vclock {1: 9} (gh-6794).

Tarantool 1.10.12

Released on 2021-12-22.

Overview

1.10.12 is the next stable release in the long-term support (LTS) version 1.10.x release series.

The label “stable” means there are 1.10.x-based applications running in production for quite a while without known crashes, incorrect results or other showstopper bugs.

This release introduces 3 improvements and resolves roughly 10 issues since the 1.10.11 version.

Compatibility

Tarantool 1.10.x is backward compatible with Tarantool 1.9.x in binary data layout, client-server protocol and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 1.10.x series.

Functionality added or changed

Build

  • Stop support of Ubuntu Trusty (14.04). (gh-6502)
  • Bump debian package compatibility level to 10 (gh-5429). Bump minimal required debhelper to version 10 (except for Ubuntu Xenial).

Bugs fixed

Core

  • Fixed a crash caused by a race between box.session.push() and closing connection (gh-6520).
  • Fixed crash in case a fiber changing box.cfg.listen is woken up (gh-6480).
  • Fixed box.cfg.listen not reverted to the old address in case the new one is invalid (gh-6092).

Replication

  • Fixed replica reconnecting to a living master on any box.cfg{replication=...} change. Such reconnects could lead to replica failing to restore connection for replication_timeout seconds (gh-4669).

LuaJIT

  • Fixed the order VM registers are allocated by LuaJIT frontend in case of BC_ISGE and BC_ISGT (gh-6227).
  • Fixed inconsistency while searching for an error function when unwinding a C protected frame to handle a runtime error (e.g. an error in __gc handler).

Lua

  • When error is raised during encoding call results, auxiliary lightuserdata value is not removed from the main Lua coroutine stack. Prior to the fix it leads to undefined behaviour during the next usage of this Lua coroutine (gh-4617).
  • Fixed Lua C API misuse, when the error is raised during call results encoding on unprotected coroutine and expected to be catched on the different one, that is protected (gh-6248).

Triggers

  • Fixed possibility crash in case when trigger removes itself. Fixed possibility crash in case when someone destroy trigger, when it’s yield (gh-6266).

Build

  • The Debian package does not depend on binutils anymore (gh-6699).
  • Fix build errors with glibc-2.34 (gh-6686).

Tarantool 1.10.11

Released on 2021-08-19.

Overview

1.10.11 is the next stable release in the long-term support (LTS) version 1.10.x release series.

The label «stable» means there are 1.10.x-based applications running in production for quite a while without known crashes, incorrect results or other showstopper bugs.

This release introduces 2 improvements and resolves roughly 18 issues since version 1.10.10.

Compatibility

Tarantool 1.10.x is backward compatible with Tarantool 1.9.x in binary data layout, client-server protocol and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 1.10.x series.

Some changes are labeled as [Breaking change]. It means that the old behavior was considered error-prone and therefore changed to protect users from unintended mistakes. However, there is a small probability that someone can rely on the old behavior, and this label is to bring attention to the things that have been changed.

Functionality added or changed

LuaJIT

  • Introduced support for LJ_DUALNUM mode in luajit-gdb.py (gh-6224).

Build

  • Fedora 34 builds are now supported (gh-6074).
  • Fedora 28 and 29 builds are no longer supported.

Bugs fixed

Core

  • [Breaking change] fiber.wakeup() in Lua and fiber_wakeup() in C became NOP on the currently running fiber. Previously they allowed “ignoring” the next yield or sleep, which resulted in unexpected erroneous wake-ups. Calling these functions right before fiber.create() in Lua or fiber_start() in C could lead to a crash (in debug build) or undefined behaviour (in release build) (gh-6043).

    There was a single use case for the previous behaviour: rescheduling in the same event loop iteration, which is not the same as fiber.sleep(0) in Lua and fiber_sleep(0) in C. It could be done in the following way:

    in C:

    fiber_wakeup(fiber_self());
fiber_yield();

    and in Lua:

    fiber.self():wakeup()
fiber.yield()

    To get the same effect in C, one can now use fiber_reschedule(). In Lua, it is now impossible to reschedule the current fiber directly in the same event loop iteration. One can reschedule self through a second fiber, but it is strongly discouraged:

    -- do not use this code
local self = fiber.self()
fiber.new(function() self:wakeup() end)
fiber.sleep(0)

  • Fixed memory leak on box.on_commit() and box.on_rollback() (gh-6025).

  • Fixed invalid results of the json module’s encode function when it was used from the Lua garbage collector. For example, this could happen in functions used as ffi.gc() (gh-6050).

  • Fixed console client connection failure in case of request timeout (gh-6249).

  • Added a missing broadcast to net.box.future:discard() so that now fibers waiting for a request result wake up when the request is discarded (gh-6250).

  • Fixed a bug when iterators became invalid (up to crash) after schema change (gh-6147).

  • Fixed crash in case of reloading a compiled module when the new module lacks some functions present in the former code. In turn, this event triggers a fallback procedure where we restore old functions, but instead of restoring each function, we process a sole entry only, leading to the crash later when these restored functions are called (gh-5968).

Vinyl

  • Fixed possible keys divergence during secondary index build, which might lead to missing tuples (gh-6045).
  • Fix crash which may occur while switching read_only mode due to duplicating transaction in tx writer list (gh-5934).
  • Fixed the race between Vinyl garbage collection and compaction that resulted in a broken vylog and recovery failure (gh-5436).

Replication

  • Fixed replication occasionally stopping with ER_INVALID_MSGPACK when the replica is under high load (gh-4040).

LuaJIT

  • Fixed optimization for single-char strings in the IR_BUFPUT assembly routine.
  • Fixed slots alignment in the lj-stack command output when LJ_GC64 is enabled (gh-5876).
  • Fixed dummy frame unwinding in the lj-stack command.
  • Fixed detection of inconsistent renames even in the presence of sunk values (gh-4252, gh-5049, gh-5118).
  • Fixed the VM register allocation order provided by LuaJIT frontend in case of BC_ISGE and BC_ISGT (gh-6227).

Lua

  • When an error occurs during encoding call results, the auxiliary lightuserdata value is not removed from the main Lua coroutine stack. Before the fix, it led to undefined behaviour during the next usage of this Lua coroutine (gh-4617).
  • Fixed a Lua C API misuse when the error is raised during call results encoding in an unprotected coroutine and expected to be caught in a different, protected coroutine (gh-6248).

Triggers

  • Fixed a possible crash in case trigger removes itself. Fixed a possible crash in case someone destroys a trigger when it yields (gh-6266).

Tarantool 1.10.10

Released on 2021-04-21.

Общие сведения

1.10.10 is the next stable release in the long-term support (LTS) version 1.10.x release series.

The label «stable» means there are 1.10.x-based applications running in production for quite a while without known crashes, incorrect results or other showstopper bugs.

This release introduces 12 improvements and resolves roughly 3 issues since version 1.10.9.

Совместимость

Tarantool 1.10.x is backward compatible with Tarantool 1.9.x in binary data layout, client-server protocol and replication protocol.

Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 1.10.x series.

Изменения или добавления функциональности

Build

  • Tarantool build infrastructure now requires CMake version 3.1 or later.
  • Binary packages for Fedora 33 (gh-5502) are now available.
  • Binary packages for CentOS 6 and Debian Jessie won’t be published since this version.
  • Backported the -DENABLE_LTO=ON/OFF CMake option (gh-3117, gh-3743). It is useful for building packages for Fedora 33 (gh-5502).
  • The built-in zstd is upgraded from v1.3.3 to v1.4.8 (part of gh-5502).
  • libcurl symbols in the case of bundled libcurl are now exported (gh-5223, gh-5542).
  • SMTP and SMTPS protocols are now enabled in the bundled libcurl (gh-4559).
  • The libcurl headers are now shipped to system path ${PREFIX}/include/tarantool when libcurl is included as a bundled library or in a static build (gh-4559).

Тестирование

  • Tarantool CI/CD has migrated to GitHub Actions (gh-5662).
  • Implemented a self-sufficient LuaJIT testing environment. As a result, LuaJIT build system is now partially ported to CMake and all testing machinery is enclosed within the tarantool/luajit repository (gh-4862, gh-5470).
  • Python 3 is now the default in the test infrastructure (gh-5652).

Исправленные ошибки

Core

  • Extensive usage of uri and uuid modules with debug log level no longer leads to crashes or corrupted results of the functions from these modules. Same problem is resolved for using these modules from the callbacks passed to ffi.gc(), and for some functions from the modules fio, box.tuple, and iconv (gh-5632).

Lua

  • Fixed the -e option, when tarantool used to enter the interactive mode when stdin is a TTY. Now, tarantool -e 'print"Hello"' doesn’t enter the interactive mode, but just prints «Hello» and exits (gh-5040).

Build

  • Recovering with force_recovery option now deletes vylog files newer than the snapshot. It helps an instance recover after incidents during a checkpoint (gh-5823).

Tarantool 1.10.9

Release: v. 1.10.9

Date: 2020-12-30 Tag: 1.10.9-0-g720ffdd23

Общие сведения

1.10.9 is the next stable release in the long-term support (LTS) version 1.10.x release series. The label “stable” means there are 1.10.x-based applications running in production for quite a while without known crashes, incorrect results or other showstopper bugs.

This release introduces one improvement and resolves roughly 7 issues since the 1.10.8 version.

Совместимость

Tarantool 1.10.x is backward compatible with Tarantool 1.9.x in binary data layout, client-server protocol and replication protocol. Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 1.10.x series.

Изменения или добавления функциональности

Build

  • Deploy packages for Fedora 32 (gh-4966).
  • Deploy packages for Debian Bullseye (gh-5638).

Разное

  • Don’t start an ‘example’ instance after installing Tarantool (gh-4507).

    Before this release the tarantool package for Debian and Ubuntu used to automatically enable and start an „example“ instance, which would listen on the TCP port 3301. Since this release the instance file is installed to /etc/tarantool/instances.available/example.lua, but isn’t enabled by default and not started anymore. You can enable and start it with the following commands:

    ln -s /etc/tarantool/instances.available/example.lua \
    /etc/tarantool/instances.enabled/example.lua
systemctl start tarantool@example

    Existing configuration will not be updated automatically at package update. If you don’t the need example instance, you can stop and disable it with the following commands:

    systemctl stop tarantool@example
rm /etc/tarantool/instances.enabled/example.lua

Исправленные ошибки

Core

  • fiber.cond:wait() now correctly throws an error when a fiber is cancelled, instead of ignoring the timeout and returning without any signs of an error (gh-5013).
  • Fixed a memory corruption issue, which was most visible on macOS, but could affect any system (gh-5312).
  • A dynamic module now gets correctly unloaded from memory in case of an attempt to load a non-existing function from it (gh-5475).
  • The fiber region (the box region) won’t be invalidated on a read-only transaction (gh-5427, gh-5623).

LuaJIT

  • Dispatching __call metamethod no longer causes address clashing (gh-4518, (gh-4649).
  • Fixed a false positive panic when yielding in debug hook (gh-5649).

Lua

  • An attempt to use a net.box connection which is not established yet now results in a correctly reported error (gh-4787).
  • Fixed a hang which occurred when tarantool ran a user script with the -e option and this script exited with an error (like with tarantool -e 'assert(false)') (gh-4983).

Tarantool 1.10.8

Release: v. 1.10.8

Date: 2020-10-22 Tag: 1.10.8-1-ge69e130

Общие сведения

1.10.8 is the next stable release of the 1.10.x series. The label “stable” means there are 1.10.x-based applications running in production for quite a while without known crashes, incorrect results or other showstopper bugs.

This release resolves roughly 7 issues since the 1.10.7 version. There may be bugs in less common areas. If you find any, feel free to report an issue at GitHub.

Совместимость

Tarantool 1.10.x is backward compatible with Tarantool 1.9.x in binary data layout, client-server protocol and replication protocol. Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 1.10.x series.

Изменения или добавления функциональности

Module API

  • Exposed the box region, key_def and several other functions in order to implement external tuple.keydef and tuple.merger modules on top of them (gh-5273, gh-5384).

Исправленные ошибки

Core

  • Fixed fibers switch-over to prevent JIT machinery misbehavior. Trace recording is aborted when fiber yields the execution. The yield occurring while the compiled code is being run (it’s likely a function with a yield underneath called via LuaJIT FFI) leads to the platform panic (gh-1700, gh-4491).
  • Fixed fibers switch-over to prevent implicit GC disabling. The yield occurring while user-defined __gc metamethod is running leads to the platform panic.

Lua

  • Fixed unhandled Lua error that might lead to memory leaks and inconsistencies in <space_object>:frommap(), <key_def_object>:compare(), <merge_source>:select() (gh-5382).

LuaJIT

  • Fixed the error occurring on loading luajit-gdb.py with Python2 (gh-4828).

Разное

  • Fixed potential lag on boot up procedure when system’s password database is slow in access (gh-5034).

Module API

  • Get rid of typedef redefinitions for compatibility with C99 (gh-5313).

Tarantool 1.10.7

Release: v. 1.10.7

Date: 2020-07-17 Tag: 1.10.7-1-gb93a33a

Общие сведения

1.10.7 is the next stable release of the 1.10.x series. The label “stable” means there are 1.10.x-based applications running in production for quite a while without known crashes, incorrect results or other showstopper bugs.

This release resolves roughly 14 issues since 1.10.6. There may be bugs in less common areas. If you find any, feel free to report an issue at GitHub.

Совместимость

Tarantool 1.10.x is backward compatible with Tarantool 1.9.x in binary data layout, client-server protocol and replication protocol. Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 1.10.x series.

Исправленные ошибки

Core

  • Fixed a bug in C module reloading (gh-4945).
  • Fixed races and corner cases in box (re)configuration (gh-4231).
  • Fixed check of index field map size which led to crash (gh-5084).
  • Fixed wrong mpsgpack extension type in an error message at decoding (gh-5017).

Lua

  • Fixed error while closing socket.tcp_server socket (gh-4087).

LuaRocks

  • Don’t ruin rock name when freshly installing *.all.rock with dependencies (gh-4704).

Vinyl

  • Fixed crash during compaction due to tuples with size exceeding vinyl_max_tuple_size setting (gh-4864).
  • Fixed crash during recovery of vinyl index due to the lack of file descriptors (gh-4805).
  • Fixed crash during executing upsert changing primary key in debug mode (gh-5005).
  • Fixed crash due to triggered dump process during secondary index creation (gh-5042).
  • Fixed crash/deadlock (depending on build type) during dump process scheduling and concurrent DDL operation (gh-4821).
  • Fixed crash during read of prepared but still not yet not committed statement (gh-3395).
  • Fixed squashing set and arithmetic upsert operations (gh-5106).
  • Create missing folders for vinyl spaces and indexes if needed to avoid confusing fails of tarantool started from backup (gh-5090).
  • Fixed crash during squash of many (more than 4000) upserts modifying the same key (gh-4957).

Tarantool 1.10.6

Release: v. 1.10.6

Date: 2020-04-20 Tag: 1.10.6-1-g47c009a

Общие сведения

1.10.6 is the next stable release of the 1.10.x series. The label “stable” means there are 1.10.x-based applications running in production for quite a while without known crashes, incorrect results or other showstopper bugs.

This release resolves roughly 20 issues since 1.10.5. There may be bugs in less common areas. If you find any, feel free to report an issue at GitHub.

Совместимость

Tarantool 1.10.x is backward compatible with Tarantool 1.9.x in binary data layout, client-server protocol and replication protocol. Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 1.10.x series.

Исправленные ошибки

Core

  • fiber.storage is cleaned between requests, and can be used as a request-local storage. Previously fiber.storage could contain some old values in the beginning of an iproto request execution, and it needed to be nullified manually. Now the cleanup is unneeded (gh-4662).
  • tuple/space/index:update()/upsert() were fixed not to turn a value into an infinity when a float value was added to or subtracted from a float column and exceeded the float value range (gh-4701).
  • Make RTREE indexes handle the out of memory error: before this fix, OOM during the recovery of an RTREE index resulted in segmentation fault (gh-4619).
  • Add cancellation guard to avoid WAL thread stuck (gh-4127).

Репликация

  • Fix the rebootstrap procedure not working if the replica itself is listed in box.cfg.replication (gh-4759).
  • Fix possible user password leaking via replication logs (gh-4493).
  • Local space operations are now counted in 0th vclock component. Every instance may have its own 0-th vclock component not matching others’. Local space operations are not replicated at all, even as NOPs (gh-4114).
  • Gc consumers are now ordered by their vclocks and not by vclock signatures. Only the WALS that contain no entries needed by any of the consumers are deleted (gh-4114).

Lua

  • json: :decode() doesn’t spoil instance’s options with per-call ones (when it is called with the second argument) (gh-4761).
  • os.environ() is now changed when os.setenv() is called (gh-4733).
  • netbox.self:call/eval() now returns the same types as netbox_connection:call/eval. Previously it could return a tuple or box.error cdata (gh-4513).
  • libev: backport fix for listening for more then 1024 file descriptors on Mac OS (gh-3867).

HTTP client

  • When building Tarantool with bundled libcurl, link it with the c-ares library by default (gh-4591).

LuaJIT

  • __pairs/__ipairs metamethods handling is removed since we faced the issues with the backward compatibility between Lua 5.1 and Lua 5.2 within Tarantool modules as well as other third party code (gh-4770).
  • Introduce luajit-gdb.py extension with commands for inspecting LuaJIT internals. The extension obliges one to provide gdbinfo for libluajit, otherwise loading fails. The extension provides the following commands:
    • lj-arch dumps values of LJ_64 and LJ_GC64 macro definitions
    • lj-tv dumps the type and GCobj info related to the given TValue
    • lj-str dumps the contents of the given GCstr
    • lj-tab dumps the contents of the given GCtab
    • lj-stack dumps Lua stack of the given lua_State
    • lj-state shows current VM, GC and JIT states
    • lj-gc shows current GC stats
  • Fix string to number conversion: current implementation respects the buffer length (gh-4773).
  • “FFI sandwich”(*) detection is introduced. If sandwich is detected
    while trace recording the recording is aborted. The sandwich detected while mcode execution leads to the platform panic.
  • luaJIT_setmode call is prohibited while mcode execution and leads to the platform panic.

(*) The following stack mix is called FFI sandwich:

Lua-FFI -> C routine -> Lua-C API -> Lua VM

This sort of re-entrancy is explicitly not supported by LuaJIT compiler. For more info see (gh-4427).

Vinyl

  • Fix assertion fault due to triggered dump process during secondary index build (gh-4810).

Разное

  • Fix crashes at attempts to use -e and -l command line options concatenated with their values, like this: -eprint(100) (gh-4775).
  • Update libopenssl version to 1.1.1f since the previous one was EOLed (gh-4830).

Building from sources

  • Fix static build (-DBUILD_STATIC=ON) when libunwind depends on liblzma (gh-4551).

Tarantool 1.10.5

Release: v. 1.10.5

Date: 2020-01-14 Tag: 1.10.5-0-g83a2ae9

Общие сведения

1.10.5 is the next stable release of the 1.10.x series. The label “stable” means there are 1.10.x-based applications running in production for quite a while without known crashes, incorrect results or other showstopper bugs.

This release resolves roughly 30 issues since 1.10.4. There may be bugs in less common areas. If you find any, feel free to report an issue at GitHub.

Совместимость

Tarantool 1.10.x is backward compatible with Tarantool 1.9.x in binary data layout, client-server protocol and replication protocol. Please upgrade using the box.schema.upgrade() procedure to unlock all the new features of the 1.10.x series.

Изменения или добавления функциональности

Lua

  • Exit gracefully when a main script throws an error: notify systemd, log the error (gh-4382).
  • Enable __pairs and __ipairs metamethods from Lua 5.2 (gh-4560). We still conform Lua 5.1 API that is not always compatible with Lua 5.2. The change is only about those metamethods.

Разное

  • Add package builds and deployment for the following Linux distros:

Исправленные ошибки

Core

  • fiber: make sure the guard page is created; refuse to create a new fiber otherwise (gh-4541). It is possible in case of heavy memory usage, say, when there is no resources to split VMAs.
  • Forbid 00000000-0000-0000-0000-000000000000 as the value of box.cfg({<...>}) options: replicaset_uuid and instance_uuid (gh-4282). It did not work as expected: the nil UUID was treated as absence of the value.
  • Update cache of universe privileges without reconnect (gh-2763).
  • net.box: don’t fire the on_connect trigger on schema update (gh-4593). Also don’t fire the on_disconnect trigger if a connection never entered into the active state (e.g. when the first schema fetch is failed).
  • func: fix use-after-free on function unload. fce9cf96
  • Don’t destroy a session until box.session.on_disconnect(<...>) triggers are finished (gh-4627). This means, for example, that box.session.id() can be safely invoked from the on_disconnect trigger. Before this change box.session.id() returned garbage (usually 0) after yield in the on_disconnect trigger. Note: tarantool/queue module is affected by this problem in some scenarios. It is especially suggested to update Tarantool at least to this release if you’re using this module.
  • Handle OOM gracefully during allocating a buffer for binary protocol response. 5c5a4e2d
  • func: Fix box.schema.func.drop(<..>) to unload unused modules (gh-4648). Also fix box.schema.func.create(<..>) to avoid loading a module again when another function from the module is loaded.
  • Encode Lua number -2^63 as integer in msgpack.encode() and box’s functions (gh-4672).

Репликация

  • Prefer to bootstrap a replica from a fully bootstrapped instance rather than from an instance that is in the process of bootstrapping (gh-4527).

    This change enables the case when two nodes (B, C) are being bootstrapped simultaneously using the one that is already bootstrapped (A), while A is configured to replicate from {B, C} and B – from {A, C}.

  • Return immediately from box.cfg{<...>} when an instance is reconfigured with replication_connect_quorum = 0 (gh-3760).

    This change also fixes the behaviour of reconfiguration with non-zero replication_connect_quorum: box.cfg{<...>} returns immediately regardless of whether connections to upstreams are established.

  • Auto reconnect a replica if password is invalid (gh-4550).

  • Use empty password when a URI in box.cfg{replication = <...>} is like login@host:port (gh-4605).

    This behaviour matches the net.box’s one now. Explicit login:@host:port was necessary before, otherwise a replica displayed the following error:

    Missing mandatory field „tuple“ in request

  • Fix segfault during replication configuration (box.cfg{replication = <...>} call) (gh-4440, gh-4576, gh-4586, gh-4643).

  • Apply replication settings of box.cfg({<...>}) in the strict order (gh-4433).

Lua

  • Fix handling of a socket read error in the console client (console.connect(<URI>) or tarantoolctl connect/enter <...>). 1f86e6cc

  • Handle the “not enough memory” error gracefully when it is raised from lua_newthread() (gh-4556). There are several cases when a new Lua thread is created:

    • Start executing a Lua function call or an eval request (from a binary protocol, SQL or with box.func.<...>:call()).
    • Create of a new fiber.
    • Start execution of a trigger.
    • Start of encoding into a YAML format (yaml.encode()).

  • Fix stack-use-after-scope in json.decode() (gh-4637).

  • Allow to use cdata<struct ibuf *> (e.g. buffer.IBUF_SHARED) as the argument to msgpack.encode(). 6d38f0c5 Before this change the cdata<struct ibuf> type was allowed, but not the corresponding pointer type.

  • A pointer returned by msgpack.decode*(cdata<[char] const *>) functions can be assigned to buffer.rpos now (and the same for msgpackffi) (gh-3926).

    All those functions now return cdata<char *> or cdata<const char *> depending of a passed argument. Example of the code that did not work: res, buf.rpos = msgpack.decode(buf.rpos, buf:size()).

  • Fix race in fio.mktree() when two tarantool processes create the same directory tree simultaneously (gh-4660). This problem affects tarantool/cartrige, see cartrige#gh-382.

HTTP client

  • Disable verbose mode when {verbose = false} is passed. 28f8a5eb
  • Fix assertion fail after a curl write error (gh-4232).

LuaJIT

  • Fix the “Data segment size exceeds process limit” error on FreeBSD/x64: do not change resource limits when it is not necessary (gh-4537).

  • fold: keep type of emitted CONV in sync with its mode. LuaJIT#524 This fixes the following assertion fail:

    asm_conv: Assertion `((IRType)((ir->t).irt & IRT_TYPE)) != st’ failed

Разное

  • Fix CLI boolean options handling in tarantoolctl cat <...>, such as --show-system (gh-4076).
  • Fix segfault (out of bounds access) when a stack unwinding error occurs at backtrace printing (gh-4636). Backtrace is printed on SIGFPE and SIGSEGV signals or when LuaJIT finds itself in the unrecoverable state (lua_atpanic()).
  • Clear terminal state on panic (gh-4466).

Building from sources

  • Fix OpenSSL linking problems on FreeBSD (gh-4490).
  • Fix linking problems on Mac OS when several toolchains are in PATH (gh-4587).
  • Fix GCC 9 warning on strncpy() (gh-4515).

Tarantool 1.10

Release: v. 1.10.0

Версия 1.10.4

Тип версии: стабильная (lts). Дата выхода: 2019-09-26. Тег: 1-10-4.

Release: v. 1.10.4.

Общие сведения

1.10.4 представляет собой очередную стабильную (lts) версию в серии 1.10. Пометка «стабильная» означает, что некоторые системы в течение определенного времени успешно отработали в производственной среде без известных сбоев, ненадежных результатов и прочих неисправностей.

Данная версия содержит около 50 исправлений по сравнению с версией 1.10.3.

Совместимость

Tarantool 1.10.x обратно совместим с Tarantool 1.9.x в том, что касается структуры бинарных данных, клиент-серверного протокола и протокола репликации. Чтобы воспользоваться новыми функциями серии 1.10.x, обновите версию 1.9 с помощью процедуры box.schema.upgrade().

Изменения или добавления функциональности

Исправленные ошибки

Устаревшие функции

Версия 1.10.3

Тип версии: стабильная (lts). Дата выхода: 2019-04-01. Тег: 1-10-3.

Release: v. 1.10.3.

Общие сведения

1.10.3 представляет собой очередную стабильную (lts) версию в серии 1.10. Пометка «стабильная» означает, что некоторые системы в течение определенного времени успешно отработали в производственной среде без известных сбоев, ненадежных результатов и прочих неисправностей.

Данная версия содержит 69 исправлений по сравнению с версией 1.10.2.

Совместимость

Tarantool 1.10.x обратно совместим с Tarantool 1.9.x в том, что касается структуры бинарных данных, клиент-серверного протокола и протокола репликации. Чтобы воспользоваться новыми функциями серии 1.10.x, обновите версию 1.9 с помощью процедуры box.schema.upgrade().

Изменения или добавления функциональности

Исправленные ошибки

Устаревшие функции

Версия 1.10.2

Тип версии: стабильная (lts). Дата выхода: 2018-10-13. Тег: 1-10-2.

Release: v. 1.10.2.

Данная сборка представляет собой первую стабильную (lts) версию в серии 1.10. Кроме того, Tarantool 1.10.2 представляет собой мажорную версию, версия Tarantool 1.9.2 объявлена устаревшей. Это обновление содержит 95 исправлений по сравнению с версией 1.9.2.

Tarantool 1.10.x обратно совместим с Tarantool 1.9.x в том, что касается структуры бинарных данных, клиент-серверного протокола и протокола репликации. Обновление можно произвести с помощью процедуры box.schema.upgrade().

Цель данного релиза – значительно повысить стабильность vinyl'а и реализовать автоматическую повторную настройку набора реплик в Tarantool.

Изменения или добавления функциональности:

Tarantool 1.9

Release: v. 1.9.0

Версия 1.9.0

Тип версии: стабильная. Дата выхода: 2018-02-26. Тег: 1.9.0-4-g195d446.

Release: v. 1.9.0.

Эта версия следует за стабильной версией 1.7.6. Цель данной версии – повысить стабилизацию vinyl’а и репликации типа мастер-мастер, для чего предусмотрено значительное количество новых функций. Следуйте инструкциям по загрузке по ссылке https://tarantool.io/en/download/download.html для установки пакета для вашей операционной системы.

Изменения или добавления функциональности:

  • (Security) it is now possible to block/unblock users. (gh-2898).
  • (Security) new function box.session.euid() to return effective user. Effective user can be different from authenticated user in case of setuid functions or box.session.su. (gh-2994).
  • (Security) new super role, with superuser access. Grant „super“ to guest to disable access control. (gh-3022).
  • (Security) on_auth trigger is now fired in case of both successful and failed authentication. (gh-3039).
  • (Replication/recovery) new replication configuration algorithm: if replication doesn’t connect to replication_quorum peers in replication_connect_timeout seconds, the server start continues but the server enters the new orphan status, which is basically read-only, until the replicas connect to each other. (gh-3151 and gh-2958).
  • (Репликация/восстановление) после включения репликации при запуске сервер не начинает обработку запросов на запись до синхронизации со всеми подключенными узлами.
  • (Replication/recovery) it is now possible to explicitly set instance_uuid and replica set uuid as configuration parameters. (gh-2967).
  • (Replication/recovery) box.once() no longer fails on a read-only replica but waits. (gh-2537).
  • (Replication/recovery) force_recovery can now skip a corrupted xlog file. (gh-3076).
  • (Replication/recovery) improved replication monitoring: box.info.replication shows peer ip:port and correct replication lag even for idle peers. (gh-2753 and gh-2689).
  • (Application server) new before triggers which can be used for conflict resolution in master-master replication. (gh-2993).
  • (Application server) http client now correctly parses cookies and supports http+unix:// paths. (gh-3040 and gh-2801).
  • (Application server) fio rock now supports file_exists(), rename() works across filesystems, and read() without arguments reads the whole file. (gh-2924, gh-2751 and gh-2925).
  • (Сервер приложений) ошибки в модуле fio соответствуют стандартам вызова функции в Tarantool и всегда возвращают сообщение об ошибке вместе с флагом ошибки.
  • (Application server) digest rock now supports pbkdf2 password hashing algorithm, useful in PCI/DSS compliant applications. (gh-2874).
  • (Application server) box.info.memory() provides a high-level overview of server memory usage, including networking, Lua, transaction and index memory. (gh-934).
  • (Database) it is now possible to add missing tuple fields to an index, which is very useful when adding an index along with the evolution of the database schema. gh-2988).
  • (Database) lots of improvements in field type support when creating or altering spaces and indexes. (gh-2893, gh-3011 and gh-3008).
  • (Database) it is now possible to turn on is_nullable property on a field even if the space is not empty, the change is instantaneous. (gh-2973).
  • (Database) logging has been improved in many respects: individual messages (gh-1972, gh-2743, gh-2900), more logging in cases when it was useful (gh-3096, gh-2871).
  • (Vinyl storage engine) it is now possible to make a unique vinyl index non-unique without index rebuild. (gh-2449).
  • (Vinyl storage engine) improved UPDATE, REPLACE and recovery performance in presence of secondary keys. (gh-2289, gh-2875 and gh-3154).
  • (Vinyl storage engine) space:len() and space:bsize() now work for vinyl (although they are still not exact). (gh-3056).
  • (Vinyl storage engine) recovery speed has improved in presence of secondary keys. (gh-2099).
  • (Builds) Alpine Linux support. (gh-3067).

Tarantool 1.8

Release: v. 1.8.0

Версия 1.8.1

Release type: alpha. Release date: 2017-05-17. Tag: 1.8.1. Release: https://groups.google.com/forum/#!msg/tarantool-ru/XYaoqJpc544/mSvKrYwNAgAJ or v. 1.8.1.

This is an alpha release which delivers support for a substantial subset of the ISO/IEC 9075:2011 SQL standard, including joins, subqueries and views. SQL is a major feature of the 1.8 release series, in which we plan to add support for ODBC and JDBC connectors, SQL triggers, prepared statements, security and roles, and generally ensure SQL is a first class query language in Tarantool.

Изменения или добавления функциональности:

  • A new function box.sql.execute() (later changed to box.execute in Tarantool 2.1) was added to query Tarantool databases using SQL statements, e.g.:

    tarantool> box.sql.execute([[SELECT * FROM _schema]]);

  • SQL and Lua are fully interoperable.

  • New meta-commands introduced to Tarantool’s console.

    You can now set input language to either SQL or Lua, e.g.:

    tarantool> \set language sql
tarantool> SELECT * FROM _schema
tarantool> \set language lua
tarantool> print("Hello, world!")

  • Most SQL statements are supported:

    • CREATE/DROP TABLE/INDEX/VIEW

      tarantool> CREATE TABLE table1 (column1 INTEGER PRIMARY KEY, column2 VARCHAR(100));

    • INSERT/UPDATE/DELETE statements e.g.:

      tarantool> INSERT INTO table1 VALUES (1, 'A');
...
tarantool> UPDATE table1 SET column2 = 'B';
    • SELECT statements, including complex complicated variants which include

      multiple JOINs, nested SELECTs etc. e.g.:

      tarantool> SELECT sum(column1) FROM table1 WHERE column2 LIKE '_B' GROUP BY column2;

    • WITH statements e.g.

      tarantool> WITH cte AS ( SELECT SUBSTR(column2,1,2), column1 FROM table1 WHERE column1 >= 0) SELECT * FROM cte;

    • SQL schema is persistent, so it is able to survive snapshot()/restore() sequence.

    • SQL features are described in a tutorial.

Tarantool 1.7

Release: v. 1.7.0

Версия 1.7.6

Release type: stable. Release date: 2017-11-07. Tag: 1.7.6-0-g7b2945d6c. Release: https://groups.google.com/forum/#!topic/tarantool/hzc7O2YDZUc or v. 1.7.6.

Данная сборка представляет собой очередную стабильную версию в серии 1.7. Это обновление содержит более 75 исправлений по сравнению с версией 1.7.5.

Что нового в Tarantool 1.7.6?

Добавлены новые опции:

  • net_box (время ожидания),
  • функции string,
  • форматы для спейса (имена и типы полей, задаваемые пользователем),
  • base64 (опция urlsafe), а также
  • index creation (collation, is-nullable, field names).

Несовместимые изменения:

  • Layout of box.space._index has been extended to support is_nullable and collation features. All new indexes created on columns with is_nullable or collation properties will have the new definition format. Please update your client libraries if you plan to use these new features (gh-2802).
  • fiber_name() now raises an exception instead of truncating long fiber names. We found that some Lua modules such as expirationd use fiber.name() as a key to identify background tasks. If a name is truncated, this fact was silently missed. The new behavior allows to detect bugs caused by fiber.name() truncation. Please use fiber.name(name, { truncate = true }) to emulate the old behavior (gh-2622).
  • space:format() is now validated on DML operations. Previously space:format() was only used by client libraries, but starting from Tarantool 1.7.6, field types in space:format() are validated on the server side on every DML operation, and field names can be used in indexes and Lua code. If you used space:format() in a non-standard way, please update layout and type names according to the official documentation for space formats.

Изменения или добавления функциональности:

  • Гибридная модель данных без схемы + со схемой. Раньше версии Tarantool позволяли хранить произвольный набор документов в формате MessagePack в спейсах. Начиная с версии Tarantool 1.7.6, можно использовать space:format() для определения условий и ограничений схемы для кортежей в спейсах. Определенные типы полей автоматически проверяются при каждой DML-операции, а определенные имена полей могут использоваться вместо номеров полей в Lua-коде. Добавлена новая функция tuple:tomap() для конвертации кортежа в Lua-словарь пар ключ-значение.
  • Поддержка сортировки и Юникода. По умолчанию, когда Tarantool сопоставляет строки, он берет во внимание только числовое значение каждого байта в строке. Чтобы задействовать такое распределение, как в телефонных справочниках и словарях, в Tarantool версии 1.7.6 впервые поддерживается сортировка по Таблице сортировки символов Юникода по умолчанию (Default Unicode Collation Element Table (DUCET)) и в соответствии с правилами, описанными в Техническом стандарте Юникода №10 – Алгоритм сортировки по Юникоду (Unicode® Technical Standard #10 Unicode Collation Algorithm (UTS #10 UCA)). См. сортировку.
  • NULL values in unique and non-unique indexes. By default, all fields in Tarantool are «NOT NULL». Starting from Tarantool 1.7.6, you can use is_nullable option in space:format() or inside an index part definition to allow storing NULL in indexes. Tarantool partially implements three-valued logic from the SQL standard and allows storing multiple NULL values in unique indexes (gh-1557).
  • Sequences and a new implementation of auto_increment(). Tarantool 1.7.6 introduces new sequence number generators (like CREATE SEQUENCE in SQL). This feature is used to implement new persistent auto increment in spaces (gh-389).
  • Vinyl: introduced gap locks in Vinyl transaction manager. The new locking mechanism in Vinyl TX manager reduces the number of conflicts in transactions (gh-2671).
  • net.box: on_connect and on_disconnect triggers (gh-2858).
  • Structured logging in JSON format (gh-2795).
  • (Lua) Lua: string.strip() (gh-2785).
  • (Lua) added base64_urlsafe_encode() to digest module (gh-2777).
  • Log conflicted keys in master-master replication (gh-2779).
  • Allow to disable backtrace in fiber.info() (gh-2878).
  • Implemented tarantoolctl rocks make *.spec (gh-2846).
  • Extended the default loader to look for .rocks in the parent dir hierarchy (gh-2676).
  • SOL_TCP options support in socket:setsockopt() (gh-598).
  • Partial emulation of LuaSocket on top of Tarantool Socket (gh-2727).

Инструменты разработчика:

  • Интеграция с IntelliJ IDEA с поддержкой отладки. Появилась возможность использовать IntelliJ IDEA в качестве IDE для разработки и отладки Lua-приложений для Tarantool. См. Использование IDE.
  • Integration with MobDebug remote Lua debugger (gh-2728).
  • Configured /usr/bin/tarantool as an alternative Lua interpreter on Debian/Ubuntu (gh-2730).

Новые сторонние библиотеки:

  • smtp.client – поддержка SMTP по libcurl.

Версия 1.7.5

Release type: stable. Release date: 2017-08-22. Tag: 1.7.5. Release: doc-289 or v. 1.7.5.

Данная сборка представляет собой стабильную версию в серии 1.7. Это обновление содержит более 160 исправлений по сравнению с версией 1.7.4.

Изменения или добавления функциональности:

  • (Vinyl) a new force_recovery mode to recover broken disk files. Use box.cfg{force_recovery=true} to recover corrupted data files after hardware issues or power outages (gh-2253).
  • (Vinyl) index options can be changed on the fly without rebuild. Now page_size, run_size_ratio, run_count_per_level and bloom_fpr index options can be dynamically changed via index:alter(). The changes take effect in newly created data files only (gh-2109).
  • (Vinyl) improve box.info.vinyl() and index:info() output (gh-1662).
  • (Vinyl) introduce box.cfg.vinyl_timeout option to control quota throttling (gh-2014).
  • Memtx: stable index:pairs() iterators for the TREE index. TREE iterators are automatically restored to a proper position after index’s modifications (gh-1796).
  • (Memtx) predictable order for non-unique TREE indexes. Non-unique TREE indexes preserve the sort order for duplicate entries (gh-2476).
  • (Memtx+Vinyl) dynamic configuration of max tuple size. Now box.cfg.memtx_max_tuple_size and box.cfg.vinyl_max_tuple_size configuration options can be changed on the fly without need to restart the server (gh-2667).
  • (Memtx+Vinyl) new implementation. Space truncation doesn’t cause re-creation of all indexes any more (gh-618).
  • Extended the maximal length of all identifiers from 32 to 65k characters. Space, user and function names are not limited by 32 characters anymore (gh-944).
  • Heartbeat messages for replication. Replication client now sends the selective acknowledgments for processed records and automatically re-establish stalled connections. This feature also changes box.info.replication[replica_id].vclock. to display committed vclock of remote replica (gh-2484).
  • Keep track of remote replicas during WAL maintenance. Replication master now automatically preserves xlogs needed for remote replicas (gh-748).
  • Enabled box.tuple.new() to work without box.cfg() (gh-2047).
  • box.atomic(fun, …) wrapper to execute function in a transaction (gh-818).
  • box.session.type() helper to determine session type (gh-2642).
  • Hot code reload for stored C stored procedures. Use box.schema.func.reload('modulename.function') to reload dynamic shared libraries on the fly (gh-910).
  • string.hex() and str:hex() Lua API (gh-2522).
  • Package manager based on LuaRocks. Use tarantoolctl rocks install MODULENAME to install MODULENAME Lua module from https://rocks.tarantool.org/. (gh-2067).
  • Lua 5.1 command line options. Tarantool binary now supports „-i“, „-e“, „-m“ and „-l“ command line options (gh-1265).
  • Experimental GC64 mode for LuaJIT. GC64 mode allow to operate the full address space on 64-bit hosts. Enable via -DLUAJIT_ENABLE_GC64=ON compile-time configuration option (gh-2643).
  • Syslog logger now support non-blocking mode. box.cfg{log_nonblock=true} now also works for syslog logger (gh-2466).
  • Added a VERBOSE log level beyond INFO (gh-2467).
  • Tarantool now automatically makes snapshots every hour. Please set box.cfg{checkpoint_interval=0 to restore pre-1.7.5 behavior (gh-2496).
  • Increase precision for percentage ratios provided by box.slab.info() (gh-2082).
  • Stack traces now contain symbols names on all supported platforms. Previous versions of Tarantool didn’t display meaningful function names in fiber.info() on non-x86 platforms (gh-2103).
  • Allowed to create fiber with custom stack size from C API (gh-2438).
  • Added ipc_cond to public C API (gh-1451).

Новые сторонние библиотеки:

  • http.client (built-in) - libcurl-based HTTP client with SSL/TLS support (gh-2083).
  • iconv (built-in) - bindings for iconv (gh-2587).
  • authman - API для регистрации пользователя и входа в систему с использованием email и социальных сетей.
  • document - хранит вложенные документы в Tarantool.
  • synchronized - критические секции для Lua.

Версия 1.7.4

Тип версии: предварительная версия. Дата выхода: 2017-05-12. Тег версии: 1.7.4.

Release: v. 1.7.4 or https://groups.google.com/forum/#!topic/tarantool/3x88ATX9YbY

Данная сборка представляет собой предварительную версию перед выпуском нового релиза в серии 1.7. Движок vinyl, ключевой компонент 1.7.x, обладает полностью реализованной заявленной функциональностью.

Несовместимые изменения

  • Для поддержки vinyl были внесены следующие изменения в параметры box.cfg():

    • переименование snap_dir в memtx_dir
    • переименование slab_alloc_arena (гигабайты) в memtx_memory (байты), значение, используемое по умолчанию, изменилось с 1 Гб на 256 МБ
    • переименование slab_alloc_minimal в memtx_min_tuple_size
    • переименование slab_alloc_maximal в memtx_max_tuple_size
    • slab_alloc_factor больше не используется, не применимо в 1.7.x
    • переименование snapshot_count в checkpoint_count
    • переименование snapshot_period в checkpoint_interval
    • переименование logger в log
    • переименование logger_nonblock в log_nonblock
    • переименование logger_level в log_level
    • переименование replication_source в replication
    • panic_on_snap_error = true и panic_on_wal_error = true заменены force_recovery = false

    Until Tarantool 1.8, you can use deprecated parameters for both initial and runtime configuration, but such usage will print a warning in the server log (gh-1927 and gh-2042).

  • Hot standy mode is now off by default. Tarantool automatically detects another running instance in the same wal_dir and refuses to start. Use box.cfg {hot_standby = true} to enable the hot standby mode (gh-775).

  • UPSERT via a secondary key was banned to avoid unclear semantics (gh-2226).

  • box.info and box.info.replication format was changed to display information about upstream and downstream connections ((gh-723):

    • Добавление box.info.replication[instance_id].downstream.vclock для отображения последней строки, отправленной на удаленную реплику.
    • Добавление box.info.replication[instance_id].id.
    • Добавление box.info.replication[instance_id].lsn.
    • Перемещение box.info.replication[instance_id].{vclock,status,error} в box.info.replication[instance_id].upstream.{vclock,status,error}.
    • Включение всех зарегистрированных реплик из box.space._cluster в вывод box.info.replication.
    • Переименование box.info.server.id в box.info.id
    • Переименование box.info.server.lsn в box.info.lsn
    • Переименование box.info.server.uuid в box.info.uuid
    • Переименование box.info.cluster.signature в box.info.signature
    • Возврат значения nil вместо -1 функциями box.info.id и box.info.lsn во время начальной настройки кластера.

  • net.box: добавление запрошенные параметров во все запросы:

    • изменение conn.call(func_name, arg1, arg2,...) на conn.call(func_name, {arg1, arg2, ...}, opts)
    • изменение conn.eval(func_name, arg1, arg2,...) на conn.eval(func_name, {arg1, arg2, ...}, opts)

  • Все запросы поддерживают параметры timeout = <seconds>``(время задержки в секундах), ``buffer = <ibuf> (буфер).

  • Добавление опции connect_timeout в netbox.connect().

  • netbox:timeout() and conn:timeout() are now deprecated. Use netbox.connect(host, port, { call_16 = true }) for 1.6.x-compatible behavior (gh-2195).

  • systemd configuration changed to support Type=Notify / sd_notify(). Now systemctl start tarantool@INSTANCE will wait until Tarantool has started and recovered from xlogs. The recovery status is reported to systemctl status tarantool@INSTANCE (gh-1923).

  • log module now doesn’t prefix all messages with the full path to tarantool binary when used without box.cfg() (gh-1876).

  • require('log').logger_pid() was renamed to require('log').pid() (gh-2917).

  • Removed Lua 5.0 compatible defines and functions (gh-2396):

    • luaL_Reg заменяет удаленный luaL_reg
    • lua_objlen(L, i) заменяет удаленный luaL_getn(L, i)
    • Удаление luaL_setn(L, i, j) (пустая операция)
    • luaL_ref(L, lock) заменяет удаленный lua_ref(L, lock)
    • lua_rawgeti(L, LUA_REGISTRYINDEX, (ref)) заменяет удаленный lua_getref(L,ref)
    • luaL_unref(L, ref) заменяет удаленный lua_unref(L, ref).
    • math.fmod() заменяет удаленный math.mod()
    • string.gmatch() заменяет удаленный string.gfind()

Изменения или добавления функциональности:

  • (Vinyl) multi-level compaction. The compaction scheduler now groups runs of the same range into levels to reduce the write amplification during compaction. This design allows Vinyl to support 1:100+ ram:disk use-cases (gh-1821).

  • (Vinyl) bloom filters for sorted runs. Bloom filter is a probabilistic data structure which can be used to test whether a requested key is present in a run file without reading the actual file from the disk. Bloom filter may have false-positive matches but false-negative matches are impossible. This feature reduces the number of seeks needed for random lookups and speeds up REPLACE/DELETE with enabled secondary keys (gh-1919).

  • (Vinyl) key-level cache for point lookups and range queries. Vinyl storage engine caches selected keys and key ranges instead of entire disk pages like in traditional databases. This approach is more efficient because the cache is not polluted with raw disk data (gh-1692).

  • (Vinyl) implemented`). Now all in-memory indexes of a space store pointers to the same tuples instead of cached secondary key index data. This feature significantly reduces the memory footprint in case of secondary keys (gh-1908).

  • (Vinyl) new implementation of initial state transfer of JOIN command in replication protocol. New replication protocol fixes problems with consistency and secondary keys. We implemented a special kind of low-cost database-wide read-view to avoid dirty reads in JOIN procedure. This trick wasn’t not possible in traditional B-Tree based databases (gh-2001).

  • (Vinyl) index-wide mems/runs. Removed ranges from in-memory and and the stop layer of LSM tree on disk (gh-2209).

  • (Vinyl) coalesce small ranges. Before dumping or compacting a range, consider coalescing it with its neighbors (gh-1735).

  • (Vinyl) implemented transnational journal for metadata. Now information about all Vinyl files is logged in a special .vylog file (gh-1967).

  • (Vinyl) implemented consistent secondary keys (gh-2410).

  • (Memtx+Vinyl) implemented low-level Lua API to create consistent backups. of Memtx + Vinyl data. The new feature provides box.backup.start()/stop() functions to create backups of all spaces. box.backup.start() pauses the Tarantool garbage collector and returns the list of files to copy. These files then can be copied be any third-party tool, like cp, ln, tar, rsync, etc. box.backup.stop() lets the garbage collector continue. Created backups can be restored instantly by copying into a new directory and starting a new Tarantool instance. No special preparation, conversion or unpacking is needed (gh-1916).

  • (Vinyl) added statistics for background workers to box.info.vinyl() (gh-2005).

  • (Memtx+Vinyl) reduced the memory footprint for indexes which keys are sequential and start from the first field. This optimization was necessary for secondary keys in Vinyl, but we optimized Memtx as well (gh-2046).

  • LuaJIT was rebased on the latest 2.1.0b3 with out patches (gh-2396):

    • Добавлен бэкенд для JIT-компилятора для архитектуры ARM64
    • Добавлен бэкенд и интерпретатор для JIT-компилятора для архитектуры MIPS64
    • Добавлены некоторые расширения для Lua 5.2 и Lua 5.3
    • Исправление нескольких ошибок
    • Удалены устаревшие функции Lua 5.0 (см. несовместимые изменения выше).

  • Запущен новый умный алгоритм хеширования строк в LuaJIT, чтобы избежать замедления работы в случае множества коллизий. Разработали Юрий Соколов (@funny-falcon) и Ник Заварицкий (@mejedi). См. https://github.com/tarantool/luajit/pull/2.

  • box.snapshot() now updates mtime of a snapshot file if there were no changes to the database since the last snapshot. (gh-2045).

  • Implemented space:bsize() to return the memory size utilized by all tuples of the space. Contributed by Roman Tokarev (@rtokarev). (gh-2043).

  • Новые функции Lua/C вынесены в общедоступный API:

    • luaT_pushtuple, luaT_istuple (gh-1878)
    • luaT_error, luaT_call, luaT_cpcall (gh-2291)
    • luaT_state (gh-2416)

  • Exported new Box/C functions to public API: box_key_def, box_tuple_format, tuple_compare(), tuple_compare_with_key(). (gh-2225).

  • xlogs now can be rotated based on size (wal_max_size) as well as the number of written rows (rows_per_wal). (gh-173).

  • Added string.split(), string.startswith(), string.endswith(), string.ljust(), string.rjust(), string.center() API (gh-2211, gh-2214, gh-2415).

  • Added table.copy() and table.deepcopy() functions. (gh-2212).

  • Added pwd module to work with UNIX users and groups. (gh-2213).

  • Removed noisy «client unix/: connected» messages from logs. Use box.session.on_connect()/on_disconnect() triggers instead. (gh-1938).

    Триггеры box.session.on_connect()/on_disconnect()/on_auth() также срабатывают для подключений административной консоли.

  • tarantoolctl: eval, enter, connect commands now support UNIX pipes (gh-672).

  • tarantoolctl: improved error messages and added a new man page (gh-1488).

  • tarantoolctl: added filter by replica_id to cat and play commands (gh-2301).

  • tarantoolctl: start, stop and restart commands now redirect to systemctl start/stop/restart when systemd is enabled (gh-2254).

  • net.box: added buffer = <buffer> per-request option to store raw MessagePack responses into a C buffer (gh-2195).

  • net.box: added connect_timeout option (gh-2054).

  • net.box: added on_schema_reload() hook (gh-2021).

  • net.box: exposed conn.schema_version and space.connection to API (gh-2412).

  • log: debug()/info()/warn()/error() now doesn’t fail on formatting errors (gh-889).

  • crypto: added HMAC support. Contributed by Andrey Kulikov (@amdei) (gh-725).

Версия 1.7.3

Тип версии: бета. Дата выхода: 2016-12-24. Тег версии: 1.7.3-0-gf0c92aa.

Release: v. 1.7.3

Данная сборка представляет собой вторую бета-версию в серии 1.7.

Несовместимые изменения:

  • Broken coredump() Lua function was removed. Use gdb -batch -ex "generate-core-file" -p $PID instead (gh-1886).
  • Vinyl disk layout was changed since 1.7.2 to add ZStandard compression and improve the performance of secondary keys. Use the replication mechanism to upgrade from 1.7.2 beta (gh-1656).

Изменения или добавления функциональности:

  • Значительный прогресс в стабилизации движка базы данных Vinyl:
    • Исправлены большинство известных отказов системы и ошибок, выдающих плохие результаты.
    • Замена формата всех файлов с данными на XLOG/SNAP.
    • Использование механизма компрессии ZStandard для всех файлов с данными.
    • Сжатие операций UPSERT на лету и объединение горячих клавиш с помощью фонового файбера.
    • Значительное улучшение производительности index:pairs() и index:count().
    • Удаление ненужных конфликтов из транзакций.
    • Уровень In-memory по большей части заменен структурами данных memtx.
    • В большинстве случаев используются специализированные распределители ресурсов.
  • Мы все еще активно работаем над Vinyl’ом и планируем добавить многоуровневое слияние и улучшить производительность в работе со вторичными ключами в версии 1.7.4. Это подразумевает изменение формата данных.
  • Support for DML requests for space:on_replace() triggers (gh-587).
  • UPSERT can be used with the empty list of operations (gh-1854).
  • Lua functions to manipulate environment variables (gh-1718).
  • Lua library to read Tarantool snapshots and xlogs (gh-1782).
  • New play and cat commands in tarantoolctl (gh-1861).
  • Улучшена поддержка большого количества активных сетевых клиентов. Проблема #5#1892.
  • Support for space:pairs(key, iterator-type) syntax (gh-1875).
  • Automatic cluster bootstrap now also works without authorization (gh-1589).
  • Replication retries to connect to master indefinitely (gh-1511).
  • Temporary spaces now work with box.cfg { read_only = true } (gh-1378).
  • The maximum length of space names increased to 64 bytes (was 32) (gh-2008).

Версия 1.7.2

Тип версии: бета. Дата выхода: 2016-09-29. Тег версии: 1.7.2-1-g92ed6c4.

Release: https://groups.google.com/forum/#!topic/tarantool-ru/qUYUesEhRQg or v. 1.7.2

Данная сборка представляет собой версию в серии 1.7.

Несовместимые изменения:

  • A new binary protocol command for CALL, which no more restricts a function to returning an array of tuples and allows returning an arbitrary MsgPack/JSON result, including scalars, nil and void (nothing). The old CALL is left intact for backward compatibility. It will be removed in the next major release. All programming language drivers will be gradually changed to use the new CALL (gh-1296).

Изменения или добавления функциональности:

  • Разработка движка базы данных Vinyl, наконец, перешла в бета-стадию. В данной версии исправлены более 90 ошибок в Vinyl’е, в частности, удаление непредсказуемых скачков задержки отклика, все известные отказы системы и ошибки, выдающие плохие результаты или их отсутствие.
    • новая архитектура на основе кооперативной многозадачности для устранения скачков задержки отклика,
    • поддержка непоследовательных составных ключей,
    • поддержка вторичных ключей,
    • поддержка auto_increment(),
    • типы полей в индексах: number (число), integer (целое число), scalar (скаляр),
    • операции INSERT, REPLACE и UPDATE возвращают новый кортеж, как в memtx’е.
  • Мы все еще активно работаем над Vinyl’ом и планируем добавить механизм компрессии zstd и новый распределитель ресурсов для Vinyl’а в версии 1.7.3. Это подразумевает изменение формата данных, который планируется внедрить до того, как версия 1.7 станет общедоступной.
  • Tab-based autocompletion in the interactive console, require('console').connect(), tarantoolctl enter and tarantoolctl connect commands (gh-86 and gh-1790). Use the TAB key to auto complete the names of Lua variables, functions and meta-methods.
  • A new implementation of net.box improving performance and solving problems when the Lua garbage collector handles dead connections (gh-799, gh-800, gh-1138 and gh-1750).
  • Появилась компрессия снимков memtx и xlog-файлов на лету с использованием быстрого алгоритма компрессии ZStandard. Компрессия настраивается автоматически для получения оптимального соотношения между использованием ЦП и пропускной способностью диска.
  • fiber.cond() - a new synchronization mechanism for cooperative multitasking (gh-1731).
  • Tarantool теперь можно устанавливать из универсальных Snappy-пакетов (http://snapcraft.io/) с помощью команды snap install tarantool --channel=beta.

Новые модули и пакеты:

  • curl - неблокирующие привязки для libcurl
  • prometheus - сборщик метрик Prometheus для Tarantool
  • gis - полнофункциональное геопространственное расширение для Tarantool
  • mqtt - клиент MQTT-протокола для Tarantool
  • luaossl - самый полноценный OpenSSL-модуль во вселенной Lua

Устаревшие, удаленные и несовместимые функции:

  • num and str fields type names are deprecated, use unsigned and string instead (gh-1534).

  • space:inc() and space:dec() were removed (deprecated in 1.6.x) (gh-1289).

  • fiber:cancel() is now asynchronous and doesn’t wait for the fiber to end (gh-1732).

  • Implicit error-prone tostring() was removed from digest API (gh-1591).

  • Поддержка SHA-0 (digest.sha()) прекращается по причине обновления OpenSSL.

  • net.box now uses one-based indexes for space.name.index[x].parts (gh-1729).

  • Бинарный файл Tarantool будет динамически связываться с libssl.so во время компиляции вместо загрузки во время выполнения.

  • Пакеты Debian и Ubuntu будут использовать встроенную конфигурацию systemd вместе с вышедшими из употребления скриптами sysvinit.

    В systemd появляется возможность управления несколькими экземплярами. Чтобы обновить, выполните следующие действия:

    1. Установите новые пакеты версии 1.7.2.
    2. Убедитесь в наличии файла ИМЯ_ЭКЗЕМПЛЯРА.lua в директории /etc/tarantool/instances.enabled.
    3. Остановите ЭКЗЕМПЛЯР с помощью tarantoolctl stop ИМЯ_ЭКЗЕМПЛЯРА.
    4. Запустите ЭКЗЕМПЛЯР с помощью systemctl start tarantool@ИМЯ_ЭКЗЕМПЛЯРА.
    5. Включите ЭКЗЕМПЛЯР во время загрузки системы с помощью systemctl enable tarantool@ИМЯ_ЭКЗЕМПЛЯРА.
    6. Введите команду systemctl disable tarantool; update-rc.d tarantool remove, чтобы отключить надстройки, совместимые с sysvinit.

    Refer to (gh-1291), comment and the administration chapter for additional information.

  • Debian and Ubuntu packages start a ready-to-use example.lua instance on a clean installation of the package. The default instance grants universe permissions for guest user and listens on «localhost:3313».

  • Пакеты для Fedora 22 объявлены устаревшими (прекращение поддержки).

Версия 1.7.1

Тип версии: альфа. Дата выхода: 2016-07-11.

Release: https://groups.google.com/forum/#!topic/tarantool/KGYj3VKJKb8 or v. 1.7.1

Данная сборка представляет собой первую альфа-версию в серии 1.7. Основной функцией данной версии является новый движок базы данных под названием «vinyl». Vinyl представляет собой оптимизированный для записи движок базы данных, который позволяет сохранять объем сохраняемых данных, превышающий объем доступной памяти в 10-100 раз. Vinyl является продолжением движка Sophia из версии 1.6, а именно ответвлением и дальним родственником Sophia Дмитрия Симоненко. Новый Vinyl заменяет Sophia. Он реализован в виде журнально-структурированного дерева со слиянием (log-structured merge tree – LSM-tree). Однако усовершенствование таких традиционных недостатков журнально-структурированных хранилищ, как низкая производительность при чтении и непредсказуемая задержка во времени при записи, стоит больших усилий. Отдельный индекс секционирован по диапазонам между многими структурами данных LSM, в каждой из который находятся собственные буферы оперативной памяти регулируемого размера. Секционирование по диапазонам позволяет осуществить слияние LSM-уровней, чтобы добиться большей детализации, а также отдать приоритет горячим диапазонам по отношению к холодным в том, что касается доступа к ресурсам, таким как оперативная память и ввод-вывод. Планировщик слияний предназначен для сведения времени задержки записи к минимуму, а также для поддержания производительности при чтении в приемлемых пределах. На сегодняшний день Vinyl поддерживает только первичные индексы. Индекс может состоять из 256 частей, как в MemTX’е, по сравнению с 8 в Sophia. Поддерживает чтение по компонентам ключа. Вскоре ожидается поддержка непоследовательных составных ключей, а также вторичных ключей. Наше намерение заключается в том, чтобы убрать любые ограничения, которые есть сейчас в Vinyl’е, чтобы сделать его полноценным компонентом Tarantool.

Изменения или добавления функциональности:

  • Дисковый движок, который в более ранних версиях Tarantool назывался sophia или phia, заменен новым движком под названием vinyl.
  • Добавлены новые типы индексируемых полей.
  • Обновлена версия LuaJIT.
  • Поддерживается автоматическая настройка набора реплик, что существенно упрощает настройку нового набора реплик.
  • Функция space_object:inc() объявлена устаревшей.
  • Функция space_object:dec() объявлена устаревшей.
  • Добавлена функция space_object:bsize().
  • Удалена функция box.coredump(), аналог см. в главе Создание дампов памяти.
  • Добавлена опция настройки hot_standby (горячий резерв).
  • Исправленные или переименованные конфигурационные параметры:
    • slab_alloc_arena (в гигабайтах) в memtx_memory (в байтах),
    • slab_alloc_minimal в memtx_min_tuple_size,
    • slab_alloc_maximal в memtx_max_tuple_size,
    • replication_source в replication,
    • snap_dir в memtx_dir,
    • logger в log,
    • logger_nonblock в log_nonblock,
    • snapshot_count в checkpoint_count,
    • snapshot_period в checkpoint_interval,
    • panic_on_wal_error и panic_on_snap_error объединены в force_recovery.
  • В версиях Tarantool до 1.8 можно использовать устаревшие параметры как для начальной, так и для рабочей конфигурации, но в таком случае Tarantool выдаст предупреждение. Также можно указывать как устаревшие, так и новые параметры при условии, что их значения согласованы. В противном случае, Tarantool выдаст ошибку.
  • У кластера репликации появилась возможность автоматической настройки, что существенно упрощает настройку нового кластера.
  • Новые индексируемые типы данных: INTEGER (целое число) и SCALAR (скаляр).
  • Рефакторинг кода и улучшение производительности.
  • LuaJIT обновлен до версии 2.1-beta116.

Tarantool 1.6

Release: v. 1.6.0

Версия 1.6.9

Release type: maintenance. Release date: 2016-09-27. Release tag: 1.6.9-4-gcc9ddd7. Release: v. 1.6.9

Since February 15, 2017, due to Tarantool issue (gh-2040) there no longer is a storage engine named sophia. It will be superseded in version 1.7 by the vinyl storage engine.

Несовместимые изменения:

  • Поддержка SHA-0 (digest.sha()) прекращается по причине обновления OpenSSL.
  • Бинарный файл Tarantool будет динамически связываться с libssl.so во время компиляции вместо загрузки во время выполнения.
  • Пакеты для Fedora 22 объявлены устаревшими (прекращение поддержки).

Изменения или добавления функциональности:

  • Tab-based autocompletion in the interactive console (gh-86).
  • LUA_PATH and LUA_CPATH environment variables taken into account, like in PUC-RIO Lua (gh-1428).
  • Search for .dylib as well as for .so libraries in OS X (gh-810).
  • A new box.cfg { read_only = true } option to emulate master-slave behavior (gh-246).
  • if_not_exists = true option added to box.schema.user.grant (gh-1683).
  • clock_realtime()/monotonic() functions added to the public C API (gh-1455).
  • space:count(key, opts) introduced as an alias for space.index.primary:count(key, opts) (gh-1391).
  • Upgrade script for 1.6.4 -> 1.6.8 -> 1.6.9 (gh-1281).
  • Support for OpenSSL 1.1 (gh-1722).

Новые модули и пакеты:

  • curl - неблокирующие привязки для libcurl
  • prometheus - сборщик метрик Prometheus для Tarantool
  • gis – полнофункциональное геопространственное расширение для Tarantool.
  • mqtt – клиент MQTT-протокола для Tarantool
  • luaossl - самый полноценный OpenSSL-модуль во вселенной Lua

Версия 1.6.8

Release type: maintenance. Release date: 2016-02-25. Release tag: 1.6.8-525-ga571ac0. Release: v. 1.6.8

Несовместимые изменения:

  • RPM-пакеты для CentOS 7 / RHEL 7 Fedora 22+ будут использовать встроенную конфигурацию systemd без устаревших скриптов sysvinit. В systemd появляется возможность управления несколькими экземплярами. Чтобы обновить, выполните следующие действия:

    1. Убедитесь в наличии файла ИМЯ_ЭКЗЕМПЛЯРА.lua в директории /etc/tarantool/instances.available.
    2. Остановите ЭКЗЕМПЛЯР с помощью tarantoolctl stop ИМЯ_ЭКЗЕМПЛЯРА.
    3. Запустите ЭКЗЕМПЛЯР с помощью systemctl start tarantool@ИМЯ_ЭКЗЕМПЛЯРА.
    4. Enable INSTANCENAME during system boot using systemctl enable tarantool@INTANCENAME.

    Директория /etc/tarantool/instance.enabled больше не используется для платформ, запускаемых по systemd.

    Для получения дополнительной информации см. главу по администрированию серверной части.

  • Sophia was upgraded to v2.1 to fix upsert, memory corruption and other bugs. Sophia v2.1 doesn’t support old v1.1 data format. Please use Tarantool replication to upgrade (gh-1222).

  • Ubuntu Vivid, Fedora 20, Fedora 21 объявлены устаревшими по причине прекращения поддержки.

  • i686-пакеты объявлены устаревшими. Используйте наши спецификации по RPM и DEB для сборки на своей инфраструктуре.

  • Обновите yum.repos.d и/или apt sources.list.d в соответствии с инструкциями по ссылке http://tarantool.org/download.html

Изменения или добавления функциональности:

  • Tarantool 1.6.8 fully supports ARMv7 and ARMv8 (aarch64) processors. Now it is possible to use Tarantool on a wide range of consumer devices, starting from popular Raspberry PI 2 to coin-size embedded boards and no-name mini-micro-nano-PCs (gh-1153). (Also qemu works well, but we don’t have real hardware to check.)

  • Tuple comparator functions were optimized, providing up to 30% performance boost when an index key consists of 2, 3 or more parts (gh-969).

  • Tuple allocator changes give another 15% performance improvement (gh-1298).

  • Replication relay performance was improved by reducing the amount of data directory re-scans (gh-1150).

  • A random delay was introduced into snapshot daemon, reducing the chance that multiple instances take a snapshot at the same time (gh-732).

  • Движок базы данных Sophia был обновлен до версии 2.1:

    • изоляция сериализуемых снимков (SSI – Serializable Snapshot Isolation),
    • режим хранения в оперативной памяти,
    • режим хранения без кэша,
    • режим хранения в кэше с подключением к базе данных,
    • внедренный AMQ-фильтр,
    • режим LRU (удаление страниц, которые дольше всего не использовались),
    • отдельная компрессия горячих и холодных данных,
    • внедрение снимков для быстрого восстановления,
    • реорганизация и исправление ошибок в upsert,
    • новые метрики производительности.

    Обратите внимание на «Несовместимые изменения» выше.

  • Allow to remove servers with non-zero LSN from _cluster space (gh-1219).

  • net.box now automatically reloads space and index definitions (gh-1183).

  • The maximal number of indexes in space was increased to 128 (gh-1311).

  • New native systemd configuration with support of instance management and daemon supervision (CentOS 7 and Fedora 22+ only). Please note «Incompatible changes» above (gh-1264).

  • Пакет Tarantool принят в официальный репозиторий Fedora (https://apps.fedoraproject.org/packages/tarantool).

  • Пакет Tarantool (OS X) принят в официальный репозиторий Homebrew (https://formulae.brew.sh/formula/tarantool).

  • Clang compiler support was added on FreeBSD. (gh-786).

  • Support for musl libc, used by Alpine Linux and Docker images, was added (gh-1249).

  • Добавлена поддержка GCC 6.0.

  • Получили поддержку Ubuntu Wily, Xenial и Fedora 22, 23 и 24, для которых мы создаем официальные пакеты.

  • box.info.cluster.uuid can be used to retrieve cluster UUID (gh-1117).

  • Многочисленные исправления в документации, добавлена документация по пакетам syslog, clock, fiber.storage, встроенное практическое задание получило обновление.

Новые модули и пакеты:

  • Tarantool перешел на новую облачную инфраструктуру на основе Docker. Новый инструмент интеграции разработки buildbot значительно уменьшает время передачи коммитов в пакеты. Официальные репозитории по ссылке http://tarantool.org теперь содержат последнюю версию сервера, модулей и коннекторов. См. http://github.com/tarantool/build
  • Репозитории по ссылке http://tarantool.org/download.html were был перенесены в облачное хранилище http://packagecloud.io (при поддержке Amazon AWS). Благодарим packagecloud.io за поддержку свободного ПО!
  • memcached – внедрение текстового и бинарного протокола memcached для Tarantool. Превращает Tarantool в memcached с доступом к базе данных с репликацией по схеме мастер-мастер. См. https://github.com/tarantool/memcached
  • migrate – модуль Tarantool для миграции с версии 1.5 на версию 1.6. См. https://github.com/bigbes/migrate
  • cqueues – асинхронный Lua-каркас для работы по сети с потоками и уведомлениями (разработал @daurnimator). Проблема 1204.

Версия 1.6.7

Release type: maintenance. Release date: 2015-11-17. Release: v. 1.6.7 Incompatible changes:

  • Изменился синтаксис команды upsert, и из нее был удален дополнительный аргумент key. Первичный ключ для поиска всегда берется из кортежа, который является вторым аргументом в upsert. upsert() добавили довольно поздно в рабочем цикле, и в проекте была очевидная ошибка, которую нам пришлось исправлять. Извините.
  • Функцию fiber.channel.broadcast() удалили, потому что ее никто не использовал, и она работала некорректно.
  • Команда reload утилиты tarantoolctl переименована в``eval``.

Изменения или добавления функциональности:

  • Опция logger допускает синтаксис для вывода в системный журнал syslog. Используйте синтаксис URI, чтобы определить место назначения журнала: в файл, в конвейер или syslog.
  • replication_source принимает массив URI, так что в каждой реплике может быть до 30 узлов.
  • RTREE-индекс принимает два типа функций distance: euclid и manhattan.
  • fio.abspath() – новая функция в модуле fio для конвертации относительного пути в абсолютный.
  • Название процесса теперь можно определить с помощью встроенного модуля title.
  • В данной версии используется LuaJIT 2.1.

Новые сторонние библиотеки:

  • memcached помогает Tarantool понимать бинарный протокол Memcached. Поддержка текстового протокола находится в процессе разработки и будет добавлена в отдельный модуль без изменений основных компонентов.

Версия 1.6.6

Release type: maintenance. Release date: 2015-08-28. Release: v. 1.6.6

Tarantool версии 1.6 больше не получает значимых новых функций, но продолжает поддерживаться. Разработчики сосредоточили свои усилия на версии 1.9.

Несовместимые изменения:

  • Появляется новая схема системного спейса _index для размещения многомерных RTREE-индексов. Tarantool 1.6.6 нормально работает со старыми снимками и системными спейсами, но нельзя будет запустить Tarantool версии 1.6.5 с директорий, созданной в Tarantool версии 1.6.6, как нельзя будет ввести запрос в Tarantool 1.6.6 с net.box версии 1.6.5.
  • Переименование box.info.snapshot_pid в box.info.snapshot_in_progress

Изменения или добавления функциональности:

  • Потоковая архитектура для работы по сети. Сетевой ввод-вывод окончательно переведен на отдельный поток, что увеличит производительность отдельного экземпляра до 50%.
  • Потоковая архитектура для создания контрольных точек. Tarantool больше не делает ответвлений для создания снимка, а использует отдельный поток, получая доступ к данным с помощью вида постоянного просмотра. Это помогает устранить скачки задержки отклика во время создания снимков.
  • Хранимые процедуры на языках C/C++. Хранимые процедуры на языках C/C++ дают скорость (в 3-4 раза больше по сравнению с Lua-версией по нашим подсчетам), а также возможность неограниченного расширения. Поскольку процедуры C/C++ выполняются там же, где располагается база данных, они могут с легкостью повредить базу данных. См. API для языка C.
  • Многомерный RTREE-индекс. RTREE-индекс теперь поддерживает большое количество измерений (до 32). Cтруктура данных RTREE была оптимизирована так, чтобы действительно использовать R*-TREE. Мы работаем над дальнейшим улучшением индекса, в частности, над функцией конфигурации расстояния. См. https://github.com/tarantool/tarantool/wiki/R-tree-index-quick-start-and-usage
  • Sophia 2.1.1 с поддержкой компрессии и составных первичных ключей. См. https://groups.google.com/forum/#!topic/sophia-database/GfcbEC7ksRg
  • New upsert command available in the binary protocol and in stored functions. The key advantage of upsert is that it’s much faster with write-optimized storage (sophia storage engine), but some caveats exists as well. See (gh-905) for details. Even though upsert performance advantage is most prominent with sophia engine, it works with all storage engines.
  • Better memory diagnostics information for fibers, tuple and index arena. Try a new command box.slab.stats(), for detailed information about tuple/index slabs, fiber.info() now displays information about memory used by the fiber.
  • Операции update и delete работают с использованием вторичного индекса, если индекс уникальный.
  • Триггеры для аутентификации. Установите триггеры box.session.on_auth для отслеживания событий аутентификации. API для триггеров улучшили, чтобы он отображал все заданные триггеры, старые триггеры легко удалить.
  • Разнообразные улучшения производительности встроенного модуля net.box.
  • Оптимизация производительности BITSET-индекса.
  • panic_on_wal_error представляет собой динамический параметр конфигурации.
  • Поле iproto sync доступно в Lua как session.sync().
  • box.once() – новый метод для вызова кода однократно в течение срока жизни экземпляра и набора реплик. Используйте once() для настройки спейсов и пользователей, а также для обновления схемы в эксплуатационной среде.
  • box.error.last() возвращает последнюю ошибку в сессии.

Новые сторонние библиотеки:

  • Следующие модули LuaJIT 2.0 теперь являются встроенными: jit.*, jit.dump, jit.util, jit.vmdef. См. http://luajit.org/ext_jit.html
  • strict – встроенный пакет, который запрещает использование необъявленных переменных в Lua. Работа ведется в таком режиме, когда Tarantool компилируется с отладкой. Чтобы включить/отключить этот режим, используйте require('strict').on()/require('strict').off() соответственно.
  • pg и mysql – модули, доступные по ссылке http://rocks.tarantool.org – работают с MySQL и PostgreSQL из Tarantool.
  • gperftools rock, available at http://rocks.tarantool.org - getting performance data using Google’s gperf from Tarantool.
  • csv – встроенный модуль для разбора и загрузки данных в формате CSV (значения, разделенные запятыми).

Поддержка новой платформы:

Enterprise SDK changelog

Versioning policy

A Tarantool Enterprise SDK version consists of two parts:

<TARANTOOL_BASE_VERSION>-r<REVISION>

For example: 2.11.1-0-gc42d9735b-r589.

616

613

609

606

605

598

595

589

579

577

563

557

553

549

545

543

542

541

540

539

538

537

536

535

534

533

532

531

530

529

528

527

526

525

524

523

522

521

520

Release SDK by tags:

519

r518

r517

r516

r515

r514

r513

r512

r511

r510

r502

r498

r467

Breaking changes

  • Default audit log format was changed to CSV.

Functionality added or changed

Enterprise

  • Implemented user-defined audit events. Now it’s possible to log custom messages to the audit log from Lua (gh-65).
  • [Breaking change] Switched the default audit log format to CSV. The format can be switched back to JSON using the new box.cfg.audit_format configuration option (gh-66).
  • Implemented the audit log filter. Now, it’s possible to enable logging only for a subset of all audit events using the new box.cfg.audit_filter configuration option (gh-67).

Core

  • Implement constraints and foreign keys. Now a user can create function constraints and foreign key relations (gh-6436).
  • Changed log level of some information messages from critical to info (gh-4675).
  • Added predefined system events: box.status, box.id, box.election and box.schema (gh-6260).
  • Introduced transaction isolation levels in Lua and IPROTO (gh-6930).

Vinyl

  • Disabled the deferred DELETE optimization in Vinyl to avoid possible performance degradation of secondary index reads. Now, to enable the optimization, one has to set the defer_deletes flag in space options (gh-4501).

Lua

  • Added support of console autocompletion for net.box objects stream and future (gh-6305).

Datetime

  • Parse method to allow converting string literals in extended iso-8601
    or rfc3339 formats (gh-6731).
  • The range of supported years has been extended in all parsers to cover
    fully -5879610-06-22..5879611-07-11 (gh-6731).

Build

  • Added bundling of GNU libunwind to support backtrace feature on AARCH64 architecture and distributives that don’t provide libunwind package.
  • Re-enabled backtrace feature for all RHEL distributions by default, except for AARCH64 architecture and ancient GCC versions, which lack compiler features required for backtrace (gh-4611).

Bugs fixed

Enterprise

  • Disabled audit log unless explicitly configured (gh-39). Before this change, audit events were written to stderr if box.cfg.audit_log wasn’t set. Now, audit log is disabled in this case.
  • Disabled audit logging of replicated events (gh-59). Now, replicated events (for example, user creation) are logged only on the origin, never on a replica.

Core

  • Banned DDL operations in space on_replace triggers, since they could lead to a crash (gh-6920).
  • Fixed a bug due to which all fibers created with fiber_attr_setstacksize() leaked until the thread exit. Their stacks also leaked except when fiber_set_joinable(..., true) was used.
  • Fixed a crash in mvcc connected with secondary index conflict (gh-6452).
  • Fixed a bug which resulted in wrong space count (gh-6421).
  • Select in RO transaction now reads confirmed data, like a standalone (auotcommit) select does (gh-6452).

Replication

  • Fixed potential obsolete data write in synchronious replication due to race in accessing terms while disk write operation is in progress and not yet completed.
  • Fixed replicas failing to bootstrap when master is just re-started (gh-6966).

Lua

  • Fixed the behavior of tarantool console on SIGINT. Now Ctrl+C discards the current input and prints the new prompt (gh-2717).

Triggers

  • Fixed assertion or segfault when MP_EXT received via net.box (gh-6766).
  • Now ROUND() properly support INTEGER and DECIMAL as the first argument (gh-6988).

Datetime

  • Intervals received after datetime arithmetic operations may be improperly normalized if result was negative

    tarantool> date.now() - date.now()
---
- -1.000026000 seconds
...

    I.e. 2 immediately called date.now() produce very close values, whose difference should be close to 0, not 1 second (gh-6882).

Net.box

  • Changed the type of the error returned by net.box on timeout from ClientError to TimedOut (gh-6144).

r457

r455

Tarantool release policy

Введение

Релизная политика Tarantool меняется, чтобы стать более понятной. Вводится новый формат версионирования, похожий на семантическое версионирование (SemVer), а также новый жизненный цикл версий, предполагающий больше серий с долгосрочной поддержкой. В этом документе подробно рассказано о новой релизной политике, правилах версионирования и жизненном цикле релизных серий.

Новая релизная политика заменяет старую для следующих серий:

Вот самые важные нововведения:

Ниже вы найдете подробные сведения о новой политике версионирования.

Политика версионирования

Релизные серии и версии

В основе новой релизной политики Tarantool лежит поддержка нескольких релизных серий. У каждой серии свой жизненный цикл, и в нее входят как предварительные, так и релизные версии.

Что такое релизная серия?
Релизная серия — это ряд версий для разработки и производственной эксплуатации. Эта последовательность версий линейно развивается по определенному плану. У каждой серии свой жизненный цикл, а версии в ней обладают некоторой гарантией совместимости друг с другом и с версиями других серий. Срок поддержки каждой серии — минимум два года с выхода первого релиза.
Что такое релизная версия?

Релизная версия, или релиз — это тщательно протестированный и готовый к производственной эксплуатации дистрибутив Tarantool, привязанный к определенному коммиту. Номер релиза состоит из трех частей:

MAJOR.MINOR.PATCH

Каждое число соответствует одному из трех типов релизных версий, о чем подробно рассказано ниже.

Мажорный релиз

Мажорная релизная версия — это первый релиз в своей релизной серии. Релиз включает в себя новую функциональность и может нарушать обратную совместимость с прежними версиями. Каждый следующий мажорный релиз получает номер, в котором изменено первое число:

MAJOR.0.0

3.0.0
Минорный релиз

В минорном релизе могут вводиться новые функциональные возможности. Тем не менее он гарантированно будет совместим с более ранними версиями серии. Могут быть также исправлены ошибки. Каждый следующий минорный релиз получает номер, в котором изменено второе число:

MAJOR.MINOR.0

3.1.0
3.2.0
Патч

Патч (patch release) исправляет ошибки предыдущих версий, но не добавляет новую функциональность. Каждый следующий патч получает номер, в котором изменено третье число:

MAJOR.MINOR.PATCH

3.0.1
3.0.2

Релизы отвечают ряду требований:

  • Каждый релиз предварительно тестировался и обкатывался во внутренних проектах, пока не исчезли все сомнения в его стабильности.
  • Исправлены все обнаруженные ошибки в стандартных сценариях использования.
  • Нет регрессии, то есть нет новых ошибок в функциональности из прошлых релизов. В случае мажорного релиза, нет регрессии в функциональности из предыдущей серии.

Backwards compatibility is guaranteed between all versions in the same release series. It is also appreciated, but not guaranteed between different release series (major number changes). See compatibility guarantees page for details.

Предварительные версии

Что такое предварительная версия?

Предварительными называются версии, опубликованные для тестирования и обкатки, но не предназначенные для производственной эксплуатации. Эти версии нумеруются по тому же принципу, что и релизы, но имеют суффикс:

MAJOR.MINOR.PATCH-suffix

Ниже подробно рассказывается о четырех типах предварительных версий.

Dev-сборка

Dev-сборка (development build) отражает определенный этап разработки продукта. Такие сборки используются только в процессе разработки и внутреннего тестирования.

Dev-сборки обозначаются суффиксом, полученным командой $(git describe --always --long)-dev:

MAJOR.MINOR.PATCH-describe-dev

2.10.2-149-g1575f3c07-dev
3.0.0-alpha1-14-gxxxxxxxxx-dev
3.0.0-entrypoint-17-gxxxxxxxxx-dev
3.1.2-5-gxxxxxxxxx-dev
Альфа-версия

В альфа-версию (alpha version) включена часть функциональных возможностей, запланированных в релизной серии. Альфа-версия может быть неполной или нестабильной, а также не обладать обратной совместимостью с предыдущей серией.

Альфа-версии предназначены для пользователей, готовых попробовать новую серию на раннем этапе, а также для тех, кто разрабатывает зависимые компоненты — коннекторы и модули.

MAJOR.MINOR.PATCH-alphaN

3.0.0-alpha1
3.0.0-alpha2
Бета-версия

В бета-версию (beta version) включены все функциональные возможности, запланированные в релизной серии. Бета-версия подходит, чтобы начать разработку нового приложения.

Бета-версия позволяет проверить, насколько готова к выпуску та или иная функциональная возможность. На основании этого принимается решение, доработать ли эту возможность, удалить или заменить. Бета-версия может содержать известные ошибки новой функциональности, а также регрессионные ошибки в распространенных сценариях использования.

MAJOR.MINOR.PATCH-betaN

3.0.0-beta1
3.0.0-beta2

Note that the development of 2.10.0, the first release under the new policy, starts with version 2.10.0-beta1.

Релиз-кандидат

В релиз-кандидате (release candidate, RC) исправляются ошибки и совершенствуется функциональность. Он также помогает собирать отзывы перед публикацией релиза. Набор функциональных возможностей в релиз-кандидате такой же, как в бета-версии. Известные ошибки в типичных сценариях использования устранены, регрессионных ошибок нет.

Релиз-кандидат подходит для использования в предпроизводственной среде (staging).

MAJOR.MINOR.PATCH-rcN

3.0.0-rc1
3.0.0-rc2
3.0.1-rc1

Жизненный цикл релизной серии

Каждая релизная серия проходит три стадии:

Ранняя разработка

Стадия ранней разработки (early development) продолжается до выхода мажорного релиза. На этой стадии публикуются альфа- и бета-версии, а также релиз-кандидаты.

Стадия разделена на два этапа:

  1. Разработка и проверка новой функциональности в альфа- и бета-версиях. На этом этапе функциональные возможности могут добавляться и в некоторых случаях удаляться.
  2. Стабилизация. С момента выхода первого релиз-кандидата набор функциональных возможностей не меняется.

Поддержка

Эта стадия начинается, когда выходит первый релиз. Теперь в релизной серии могут появляться только изменения, не нарушающие обратную совместимость.

На этой стадии устраняются известные проблемы безопасности и исправляются регрессионные ошибки, возникшие в серии.

Патчи для регрессионных и других ошибок выпускаются, пока серия не перейдет со стадии поддержки на стадию прекращения поддержки (end of life, EOL).

Решение о том, исправить ли конкретную ошибку в релизной серии, принимается в зависимости от того, насколько проблема серьезна, сложно ли будет ее устранить в предыдущих версиях и нарушит ли исправление обратную совместимость.

На этой стадии в релизной серии могут выпускаться новые функциональные возможности, но все они будут обратно совместимы с предыдущими версиями. Кроме того, может быть выпущен релиз-кандидат, чтобы собрать отзывы пользователей перед выходом релиза.

В течение периода поддержки в релизной серии выпускаются обновления для новых версий дистрибутивов Linux.

Срок поддержки для каждой серии — как минимум два года.

Прекращение поддержки

Стадия прекращения поддержки (end of life, EOL) для серии наступает, когда опубликован последний релиз в этой серии. После этого серия прекращает обновляться.

Для серий, достигших этой стадии, поддержка не гарантируется. Скорее всего, для них не будут выходить обновления, связанные с работой модулей, коннекторов и инструментов.

Стадия прекращения поддержки для релизной серии может наступить только тогда, когда большинство производственных сред, с которыми Tarantool работает по SLA и другим соглашениям, обновится до более новой серии.

Версии по стадиям жизненного цикла

Стадия Типы версий Примеры
Ранняя разработка Альфа, бета, релиз-кандидат 
3.0.0-alpha1
3.0.0-beta1
3.0.0-rc1
3.0.0-dev
Поддержка Релиз-кандидат, релиз 
3.0.0
3.0.1-rc1
3.0.1-dev
Прекращение поддержки – –

Пример релизной серии

На стадии ранней разработки последовательность версий в релизной серии может быть такой:

3.0.0-alpha1
3.0.0-alpha2
...
3.0.0-alpha7

3.0.0-beta1
...
3.0.0-beta5

3.0.0-rc1
...
3.0.0-rc4

3.0.0 (релиз)

Как только выпущен первый релиз, серия переходит на стадию поддержки. Дальнейшие версии могут быть опубликованы в такой последовательности:

3.0.0 (релиз новой основной версии)

3.0.1-rc1
...
3.0.1-rc4
3.0.1 (релиз с исправлением ошибок, но без функциональных изменений)

3.1.0-rc1
...
3.1.0-rc6
3.1.0 (релиз с новыми функциональными возможностями и, вероятно, дополнительными исправлениями)

Со временем стадия поддержки подходит к концу, и релизная серия выходит на стадию прекращения поддержки (end of life, EOL). С этого момента новые версии не выпускаются.

Примечание

See all currently supported Tarantool versions in Releases.

Compatibility guarantees

Backwards compatibility is guaranteed between all versions in the same release series. It is also appreciated but not guaranteed between different release series (major number changes). Pre-releases and releases of one release series are compatible in all senses defined below (any release with any release):

Binary data layout

Any newer release (its runtime) is backward compatible with any older one. It means the more recent release can work on top of data (*.xlog, *.snap, *.vylog, *.run) from the older one. All functionality of the older release can work in this configuration. The same compatibility is maintained between release series as well.

An attempt to use a new feature results in one of the options:

Binary protocol

All binary protocol requests operational in an older release keep working in a newer one. Responses have the same format, but mappings may contain fields not present in the older release.

A net.box client of an older release can work with a server running a newer release. However, net.box features introduced in the newer release won’t work. A net.box client of a newer release is fully operational with a server running a older release. However, only the features implemented in the older release will work.

Replication protocol

An instance running on a newer release can work as:

The database schema upgrade (box.schema.upgrade()) must be performed when all replicaset instances run on the same Tarantool version. An application should not lean on internal schema representation because it can be changed with the upgrade.

Lua code

If a code is processed on an older release, it will operate with the same effect on a newer one. However, only meaningful code counts. If any code throws an error but starts doing something useful, the change is considered compatible.

There is still room for new functionality: adding new options (fields in a table argument), new arguments to the end, more fields to a return table, and more return values (multireturn).

Adding a new built-in module or a new global value is considered as a compatible change.

Adding a new field to an existing metatable is okay if the field is not listed in the Lua 5.1 Reference Manual. Otherwise, it should be proven that it won’t break any meaningful code.

Examples of compatible changes:

Examples of incompatible changes:

SQL code

If any request is processed on an older release, it will operate with the same effect on a newer one (except the requests that always lead to an error).

Examples of compatible changes:

Technically, those changes may break some working code in case of a name clash, but the probability of it is negligible.

Examples of incompatible changes:

C code

If a module or a C stored procedure runs on an older release, it will operate with the same effect on a newer one.

It is okay to add a new function or structure to the public C API. It must use one of the Tarantool prefixes (box_, fiber_, luaT_, luaM_ and so on) or some new prefix.

A symbol from a used library must not be exported directly because the library may be used in a module by itself, and the clash can lead to problems. Exception: when the whole public API of the library is exported (as for libcurl).

Do not introduce new functions or structures with the lua_ and luaL_ prefixes. Those prefixes are for the Lua runtime. Use luaT_ for Tarantool-specific functions, and luaM_ for general-purpose ones.

Contributing

How to get involved in Tarantool

What is Tarantool?

Tarantool is an open source database that can store everything in RAM. Use Tarantool as a cache with the ability to save data to disk. Tarantool serves up to a million requests per second, allows for secondary index searches, and has SQL support.

In Tarantool, you can execute code alongside data. This allows for faster operations. Implement any business logic in Lua. Get rid of stale entries, sync with other data sources, implement an HTTP service.

Go to Getting Started and try Tarantool.

How to get help?

We have a special Telegram chat for contributors. We speak Russian and English in the chat.

This is the easiest way to get your questions answered. Many people are afraid to ask questions because they believe they are «wasting the experts“ time,» but we don’t really think so. Contributors are important to us.

We also have a Stack Overflow tag.

Join the chat and ask questions.

How to leave feedback, ideas, or suggestions?

You can leave your feedback or share ideas in different ways:

See an example of a feature request.

To talk to our team about a product, go to one of our chats:

If Telegram is inconvenient for you or simply isn’t working, you can leave your comment on tarantool.io. Fill out the form at the bottom of the site and leave your email. We read every request and respond to them usually within 2 days.

How to contribute

There are many ways to contribute to Tarantool:

Tarantool ecosystem

Tarantool has a large ecosystem of tools. We divide the ecosystem into four large blocks:

To start contributing, check the «good first issue» tag in the issues section of any of our repositories. These are beginner to intermediate tasks that will help you get comfortable with the tool.

See the list of tasks for the tarantool/tarantool repository.

There is a review queue in each of our repositories, so your changes may not be reviewed immediately. We usually give the first answer within two days. Depending on the ticket and its complexity, the review time may take a week or more.

Please do not hesitate to tag the maintainer in your GitHub ticket.

Read on to learn about contributing to different ecosystem blocks.

Documentation: How to report and fix problems

There are several ways to improve the documentation:

Some Tarantool projects have their documentation in the code repository. This is typical for modules, for example, metrics. This is done on purpose, so the developers themselves can update it faster. You can find instructions for building such documentation in the code repository.

If you find that the documentation provided in the README of a module or a connector is incomplete or wrong, the best way to influence this is to fix it yourself. Clone the repository, fix the bug, and suggest changes in a pull request. It will take you five minutes but it will help the whole community.

If you cannot fix it for any reason, create a ticket in the repository and report the error. It will be fixed promptly.

How to contribute to modules

Tarantool is a database with an embedded application server. This means you can write any code in C or Lua and pack it in distributable modules.

We have official and unofficial modules. Here are some of our official modules:

Official modules are provided in our organization on GitHub.

All modules are distributed through our package manager, which is pre-installed with Tarantool. That also applies to unofficial modules, which means that other users can get your module easily.

If you want to add your module to our GitHub organization, send us a message on Telegram.

Contributing to an existing module

Tasks for contributors can be found in the issues section of any repository under the «good first issue» tag. These tasks are beginner or intermediate in terms of difficulty level, so you can comfortably get used to the module of your interest.

Check the currently open tasks for the HTTP Server module.

Please see our Lua style guide.

You can find the contact of the current maintainer in the MAINTAINERS file, located in the root of the repository. If there is no such file, please let us know. We will respond within two days.

If you see that the project does not have a maintainer or is inactive, you can become its maintainer yourself. See the How to become a maintainer section.

Creating a new module

You can also create custom modules and share them with the community. Look at the module template and write your own.

How to contribute to Tarantool Core

Tarantool is written mostly in C. Some parts are in C++ and Lua. Your contributions to Tarantool Core may take longer to review because we want the code to be reliable.

To start:

In Tarantool development, we strive to follow the standards laid out in our style and contribution guides. These documents explain how to format your code and commits as well as how to write tests without breaking anything accidentally.

The guidelines also help you create patches that are easy to check, which allows quickly pushing changes to master.

Please read about our code review procedure before making your first commit.

You can suggest a patch using the fork and pull mechanism on GitHub: Make changes to your copy of the repository and submit it to us for review. Check the GitHub documentation to learn how to do it.

How to write tests

A database is a product that is expected to be as reliable as possible. We at Tarantool created test-run, a dedicated test framework for developing scripts that test Tarantool itself.

Writing your own test is not difficult. Check out the following examples:

We also have a CI workflow that automatically checks build and test coverage for new changes on all supported operating systems. The workflow is launched after every commit to the repository.

We have many tasks for QA specialists. Our QA team provides test coverage for our products, helps develop the test framework, and introduces and maintains new tools to test the stability of our releases.

For modules, we use luatest— our fork of a framework popular in the Lua community, enhanced and optimized for our tasks. See examples. of writing tests for a module.

How to contribute to language connectors

A connector is a library that provides an API to access Tarantool from a programming language. Tarantool uses its own binary protocol for access, and the connector’s task is to transfer user requests to the database and application server in the required format.

Data access connectors have already been implemented for all major languages. If you want to write your own connector, you first need to familiarize yourself with the Tarantool binary protocol. Read the protocol description to learn more.

We consider the following connectors as references:

You can look at them to understand how to do it right.

Some connectors in the Tarantool ecosystem are supported by the Tarantool team. Others are developed and supported exclusively by the community. All of them have their pros and cons. See the complete list of connectors and their recommended versions.

If you are using a community connector and want to implement new features for it or fix a bug, send your PRs via GitHub to the connector repository.

If you have questions for the author of the connector, check the MAINTAINERS file for the repository maintainer’s contact. If there is no such file, send us a message on Telegram. We will help you figure it out. We usually answer within one day.

How to contribute to tools

The Tarantool ecosystem has tools that facilitate the workflow, help with application deployment, or allow working with Kubernetes.

Here are some of the tools created by the Tarantool team:

These tools can be installed via standard package managers: ansible galaxy, yum, or apt-get.

If you have a tool that might go well in our curated Awesome Tarantool list, read the guide for contributors and submit a pull request.

How to become a maintainer

Maintainers are people who can merge PRs or commit to master. We expect maintainers to answer questions and tickets on time as well as do code reviews.

If you need to get a review but no one responds within a week, take a look at the Maintainers section of the repository’s README.md. Write to the person listed there. If you have not received an answer within 3–4 days, you can escalate the question on Telegram.

A repository may have no maintainers (empty Maintainers list in README.md), or the existing maintainers may be inactive. In this case, you can become a maintainer yourself. We think it’s better if the repository is maintained by a newbie than if the repository is dead. So don’t be shy: we love maintainers and help them figure it all out.

All you need to do is fill out this form. Tell us what repository you want to access, the reason (inactivity, the maintainer is not responding), and how to contact you. We will consider your application in 1 day and either give you the rights or tell you what else needs to be done.

How to write release notes

Below are some best practices to make changelogs consistent, neat, and human-oriented.

Language

Note that these guidelines differ from the best practice for commit message titles that suggests using the imperative mood.

Formatting

In release notes, use the following Sphinx syntax when referring to a specific version of Tarantool:

Tarantool :tarantool-release:`2.10.0`.
This is a link to the release notes on GitHub.

The result looks like this:

Tarantool v. 2.10.0. This is a link to the release notes on GitHub.

Building to contribute

To build Tarantool from source files, you need the following tools:

Quick build

To install all required dependencies, build Tarantool and run tests, choose your OS and follow the instructions:

Some additional steps might be useful:

Ubuntu/Debian

$ apt-get -y install git build-essential cmake autoconf automake libtool make \
  zlib1g-dev libreadline-dev libncurses5-dev libssl-dev libunwind-dev libicu-dev \
  python3 python3-yaml python3-six python3-gevent

$ git clone https://github.com/tarantool/tarantool.git --recursive

$ cd tarantool

$ git submodule update --init --recursive

$ make clean         # unnecessary, added for good luck
$ rm CMakeCache.txt  # unnecessary, added for good luck

$ mkdir build && cd build

$ # start initiating with build type=RelWithDebInfo
$ cmake .. -DCMAKE_BUILD_TYPE=RelWithDebInfo

$ make

$ make test

Fedora

$ dnf install -y git gcc gcc-c++ cmake  autoconf automake libtool make \
  readline-devel ncurses-devel openssl-devel zlib-devel libunwind-devel libicu-devel \
  python3-pyyaml python3-six python3-gevent

$ git clone https://github.com/tarantool/tarantool.git --recursive

$ cd tarantool

$ git submodule update --init --recursive

$ make clean         # unnecessary, added for good luck
$ rm CMakeCache.txt  # unnecessary, added for good luck

$ mkdir build && cd build

$ # start initiating with build type=RelWithDebInfo
$ cmake .. -DCMAKE_BUILD_TYPE=RelWithDebInfo

$ make

$ make test

RHEL/CentOS 7

$ yum install -y python-pip
$ yum install -y epel-release

$ curl -s https://packagecloud.io/install/repositories/packpack/backports/script.rpm.sh | bash

$ yum install -y git gcc cmake3  autoconf automake libtool make gcc-c++ zlib-devel \
  readline-devel ncurses-devel openssl-devel libunwind-devel libicu-devel \
  python3-pyyaml python3-six python3-gevent

$ git clone https://github.com/tarantool/tarantool.git --recursive

$ cd tarantool

$ git submodule update --init --recursive

$ make clean         # unnecessary, added for good luck
$ rm CMakeCache.txt  # unnecessary, added for good luck

$ mkdir build && cd build

$ # start initiating with build type=RelWithDebInfo
$ cmake3 .. -DCMAKE_BUILD_TYPE=RelWithDebInfo

$ make

$ make test

CentOS 8

$ dnf install -y epel-release

$ dnf install -y git gcc cmake3  autoconf automake libtool libarchive make gcc-c++ \
  zlib-devel readline-devel ncurses-devel openssl-devel libunwind-devel libicu-devel \
  python3-pyyaml python3-six python3-gevent

$ git clone https://github.com/tarantool/tarantool.git --recursive

$ cd tarantool

$ git submodule update --init --recursive

$ make clean         # unnecessary, added for good luck
$ rm CMakeCache.txt  # unnecessary, added for good luck

$ mkdir build && cd build

$ # start initiating with build type=RelWithDebInfo
$ cmake .. -DCMAKE_BUILD_TYPE=RelWithDebInfo

$ make

$ make test

Mac OS

This instruction is for those who use Homebrew. Refer to the full instruction for Mac OS if you use MacPorts.

$ xcode-select --install
$ xcode-select -switch /Applications/Xcode.app/Contents/Developer

$ git clone https://github.com/tarantool/tarantool.git --recursive

$ cd tarantool

$ git submodule update --init --recursive

$ brew install git openssl readline curl icu4c libiconv zlib cmake autoconf automake libtool

$ pip install --user -r test-run/requirements.txt

$ make clean         # unnecessary, added for good luck
$ rm CMakeCache.txt  # unnecessary, added for good luck

$ mkdir build && cd build

$ # start initiating with build type=RelWithDebInfo
$ cmake .. -DCMAKE_BUILD_TYPE=RelWithDebInfo

$ make

$ make test

FreeBSD

$ git clone https://github.com/tarantool/tarantool.git --recursive

$ cd tarantool

$ git submodule update --init --recursive

$ pkg install -y git cmake autoconf automake libtool gmake readline icu

$ pip install --user -r test-run/requirements.txt

$ make clean         # unnecessary, added for good luck
$ rm CMakeCache.txt  # unnecessary, added for good luck

$ mkdir build && cd build

$ # start initiating with build type=RelWithDebInfo
$ cmake .. -DCMAKE_BUILD_TYPE=RelWithDebInfo

$ gmake

$ gmake test

Additional steps

-DENABLE_DIST=ON for tarantoolctl installation

Важно

tarantoolctl is deprecated in favor of tt CLI. Find the instructions on switching from tarantoolctl to tt in Migration from tarantoolctl to tt.

The CMake option for hinting that the result will be distributed is -DENABLE_DIST=ON. With this option, make install installs tarantoolctl files in addition to tarantool files.

Make RPM and Debian packages

This step is optional. It’s only for people who want to redistribute Tarantool. We highly recommend to use official packages from the tarantool.org web-site. However, you can build RPM and Debian packages using PackPack. Consult Build RPM or Deb package using packpack for details.

Verify your Tarantool installation

$ # если tarantool установлен локально после сборки
$ tarantool
$ # - ИЛИ -
$ # если tarantool не установлен локально после сборки
$ ./src/tarantool

Tarantool запустится в интерактивном режиме.

Добавление собственного модуля

На этой странице рассказано, как создать модуль для Tarantool, а затем разместить его на странице модулей Tarantool <http://tarantool.org/rocks.html>`_ и включить его в официальные образы Tarantool для Docker.

Чтобы узнать, как разработать несложный Lua-модуль для локального использования, прочитайте практическое руководство.

Чтобы помочь разработчикам, мы создали modulekit, набор шаблонов для создания Tarantool-модулей на Lua и C.

Примечание

Чтобы использовать modulekit, необходимо предварительно установить пакет tarantool-dev. Например, в Ubuntu выполните команду:

$ sudo apt-get install tarantool-dev

Добавление собственного модуля на Lua

Подробную информацию и примеры см. в README в ветке «luakit» репозитория tarantool/modulekit.

Добавление собственного модуля на C

В некоторых случаях может потребоваться создание Tarantool-модуля на C, а не на Lua, например, для работы со специальным оборудованием или низкоуровневыми системными интерфейсами.

Подробную информацию и примеры см. в README в ветке «ckit» репозитория tarantool/modulekit.

Примечание

Вы можете аналогичным образом создавать модули на C++ при условии, что в их коде не будут выбрасываться исключения.

Рекомендации

Рекомендации для разработчиков

Как работать над дефектами

На любой, даже незначительный дефект, меняющий видимое для пользователя поведение сервера, необходимо составить отчет об ошибке. Сообщите о дефекте на GitHub.

Когда вы сообщаете об ошибке, постарайтесь сразу же приступить к тестовому сценарию. Установите текущую контрольную точку для исправления ошибки и укажите серию. Назначьте задачу на себя. Укажите статус «In progress» (выполняется). Как только патч готов, укажите статус ошибки «In review» (на рассмотрении) и отправьте версию с исправленными ошибками на рассмотрение.

После успешного рассмотрения кода опубликуйте патч и укажите статус «Closed» (закрыт).

Патчи для исправления ошибок должны содержать ссылку на страницу нужной задачи на GitHub или на идентификатор задачи. Каждому патчу должен соответствовать отдельный тест. Если в текущем окружении создать подходящий тест затруднительно, следует предупредить тестировщиков.

Когда ваш патч доходит до главной ветки проекта, нужно сделать следующее:

Как писать сообщение о коммите

Любой коммит следует описать в полезном сообщении. Следуйте нижеприведенным рекомендациям при коммитах в любой репозиторий Tarantool на GitHub.

  1. Отделяйте тему от тела сообщения пустой строкой.
  2. Постарайтесь ограничить тему сообщения примерно 50 символами.
  3. Начните тему сообщения с прописной буквы, если ей не предшествует префикс с именем подсистемы и точка с запятой:
    • memtx:
    • vinyl:
    • xlog:
    • replication:
    • recovery:
    • iproto:
    • net.box:
    • lua:
    • sql:
  4. Не заканчивайте тему сообщения точкой.
  5. Не пишите «gh-xx», «closes #xxx» в строке темы.
  6. В теме сообщения используйте повелительное наклонение. Правильно оформленная тема Git-коммита должна корректно дополнять следующее предложение: «Если применить, коммит /здесь тема сообщения/».
  7. Уместите тело сообщения в примерно 72 символа.
  8. Используйте тело сообщения, чтобы объяснить, что и почему, а не как.
  9. Привяжите задачи на GitHub в последних строках (см. как).
  10. Используйте настоящие имя и адрес электронной почты. Членам проектной команды Tarantool рекомендуется указывать почту на @tarantool.org, но это необязательно.

Шаблон:

Кратко сформулируйте изменения в пределах 50 символов.

При необходимости, более подробные объяснения.
Уместите детали в примерно 72 символов.
Иногда первая строка считается темой
коммита, а остальной текст -- телом сообщения.
Критически важна пустая строка, которая отделяет тему от тела сообщения
(если только тело не отсутствует совсем); различные средства, такие как `log`,
`shortlog` и `rebase` могут их перепутать, если нет разделения.

Объясните проблему, которую решает данный коммит. Уделите внимание тому, почему
вы вносите эти изменения, а не как (это объясняется в коде).
Есть ли побочные эффекты или другие неочевидные последствия применения этих
изменений? Здесь можно объяснить их.

Следующие абзацы идут после пустых строк.

- Можно также использовать элементы в списке.

- Как правило, в качестве маркера применяется дефис или звездочка, которой предшествует
  пробел, а между строками вставляются пустые строки, но в данном случае
  условные обозначения могут разниться.

Fixes #123
Closes #456
Needed for #859
See also #343, #789

Некоторые реальные примеры:

Based on [1] and [2].

Documentation & Localization guidelines

These guidelines aim to help the team and external contributors write, translate, publish, and collaborate on the Tarantool documentation.

The guidelines are a work in progress, and we welcome all contributions.

Оглавление:

Language and style

General style

Concise is good

People usually read technical documentation because they want something up and running quickly. Write simpler, more concise sentences.

Split the content into smaller paragraphs to improve readability. This will also eliminate the need for using |br| and help us translate content faster. Any paragraph over 6 sentences is large.

Keep your audience in mind

Consider your audience’s level. A getting started guide should be written in simpler terms than an advanced internals description.

If you choose to use metaphors to clarify a concept, make sure they are relatable for an international audience of IT professionals.

Don’t say «we»

Only use the pronoun «we» in entry-level texts like getting started guides. In other cases, avoid using «we», because it is unclear who that is exactly. Consider how Gentoo does it.

Stick to the facts

Use measurable facts instead of personal judgments. Different users may have different ideas of what «often», «slow», or «small» means.

Bad example: This parameter is rarely updated.

Good example: This parameter is updated every two hours or more rarely.

Refer to absolute time

Temporal adverbs like «today», «currently», «now», «in the future», etc. are relative – that is, they are based on the time the documentation is created.

Instead of these words, use absolute terms like version numbers or years. The meaning of those terms doesn’t change over time.

If technical documentation is tied semantically to the time it was created, it increases the risk of the documentation becoming obsolete.

Bad example: Previously, the functionality worked differently. Currently, it supports SSL.

Good example: Before version x.y.z, the functionality worked differently. Since version x.y.z, it supports SSL.

Express one idea in a sentence

Say exactly one thing in a sentence. If you want to define or clarify something, do it in a separate sentence. Simple sentences are easier to read, understand and translate.

Don’t Do
Dogs (I have three of them) are my favorite animals. Their names are Ace, Bingo and Charm; Charm is the youngest one. Dogs are my favorite animals. I have three of them. Their names are Ace, Bingo and Charm. Charm is the youngest one.
memtx (in-memory движок базы данных) используется по умолчанию, который был первым. memtx is an in-memory storage engine. It is the default and was the first to arrive.
The replica set from where the bucket is being migrated is called the source; the target replica set where the bucket is being migrated to is called the destination. The replica set from where the bucket is being migrated is called the source. The target replica set where the bucket is being migrated to is called the destination.

Put examples next to theory

It’s best if examples immediately follow the concept they illustrate. The readers wouldn’t want to look for the examples in a different part of the article.

Specify link text

When you provide a link, clearly specify where it leads. In this way, you will not mislead the reader.

Bad example:

For more details, click here.

Use this.

Good example:

For more details, refer to the documentation on making links.

Use full link names.

Formatting

Use lists and tables

Lists and tables help split heavy content into manageable chunks.

To make tables maintainable and easy to translate, use the list-table directive, as described in the Tarantool table markup reference.

Translators find it hard to work with content «drawn» with ASCII characters, because it requires adjusting the number of spaces and manually counting characters.

Bad example:

Don't "draw" tables with ASCII characters

Good example:

Use the "list-table" directive instead

Format code as code

Format large code fragments using the code-block directive, indicating the language. For shorter code snippets, make sure that only code goes in the backticks. Non-code shouldn’t be formatted as code, because this confuses users (and translators, too). Check our guidelines on writing about code.

For more about formatting, check out the Tarantool markup reference.

Word choice

Экземпляр или сервер

We say «instance» rather than «server» to refer to a Tarantool server instance. This keeps the manual terminology consistent with names like /etc/tarantool/instances.enabled in the Tarantool environment.

Wrong usage: «Replication allows multiple Tarantool servers to work with copies of the same database.»

Correct usage: «Replication allows multiple Tarantool instances to work with copies of the same database.»

Don’t use i.e. and e.g.

Don’t use the following contractions:

  • «i.e.»—from the Latin «id est». Use «that is» or «which means» instead.
  • «e.g.»—from the Latin «exempli gratia». Use «for example» or «such as» instead.

Many people, especially non-native English speakers, aren’t familiar with the «i.e.» and «e.g.» contractions or don’t know the difference between them. For this reason, it’s best to avoid using them.

Spelling and punctuation

Tarantool capitalization

The word «Tarantool» is capitalized because it’s a product name. The only context where it can start with a lowercase «t» is code. Learn more about code formatting in Tarantool documentation.

Британский или американский вариант английского

Use the US English spelling.

Check your spelling and punctuation

Consider checking spelling, grammar, and punctuation with special tools like LanguageTool or Grammarly.

Dashes

Special symbols like dashes, quotation marks, and apostrophes look the same across all Tarantool documentation in a single language. This is because the documentation builder renders specific character sequences in the source into correct typographic characters.

Tarantool documentarians are recommended to use the en dash (–) only. Type two hyphens to insert it: --. Add spaces on both sides of the dash. Don’t use a single hyphen as a dash.

Use the dash for the following purposes:

  • To separate extra information.
  • To mark a break in a sentence.
  • To mark ranges like 4–16 GB (don’t surround the dash with spaces in this case).

When indicating a range like code element 1–code element 2, escape the series of hyphens using character-level inline markup. Otherwise, the RST interpreter will perceive the dash as part of the RST syntax:

``box.begin()``\--``box.commit()``

Ending punctuation in lists and tables

The following recommendations are for the English language only. You can find similar guidelines for the Russian language in the external reference for Russian proofreaders.

Lists

There are two kinds of lists:

  • Where each item forms a complete sentence.
  • Where each item is a phrase of three or less words or a term.

In the former case, start each item with a capital letter and end with a period. In the latter case, start it with a lowercase letter and add no ending punctuation (no period, no comma, no semicolon).

A list should be formatted uniformly: choose the first or second rule for all items in a list.

The above rules are adapted from the Microsoft style guide.

The sentence preceding a list can end either with a semicolon or a period.

Don’t add redundant conjunctions like «and»/»or» before the last list item.

General English punctuation rules still apply for text in lists.

Tables

For the text in cells, use periods or other end punctuation only if the cells contain complete sentences or a mixture of fragments and sentences. (This is also a Microsoft guideline for the English language.)

Besides, make sure that your table punctuation is consistent – either all similar list/table items end with a period or they all don’t. In the example below, all items in the second column don’t have ending punctuation. Meanwhile, all items in the fourth column end with a period, because they are a mix of fragments and sentences:

Items in one column have similar ending punctuation

To learn more about table formatting, check the table markup reference.

Localization

This section covers the specifics of localizing Tarantool into Russian. If you are translating Tarantool docs into Russian, be sure to check out our translation guidelines.

Contents:

State of localization

Repository State Volume, words
Tarantool Community Edition doc 352 000
Tarantool Ansible Role tarantool-ansible-role 11 000
Tarantool Enterprise Edition tarantool-enterprise 6 000
Tarantool Data Grid tarantool-data-grid 4 000
Tarantool Metrics tarantool-metrics 4 000
Tarantool C++ Driver tarantool-cpp 4 000
Tarantool Kubernetes Operator tarantool-kubernetes-operator 2 750
Tarantool Luatest tarantool-luatest 750
Tarantool Graphana Dashboard tarantool-graphana-dashboard 500

Glossaries

Term [en] Term [ru] Description [en] Description [ru]  
space спейс A space is a container for tuples.    
tuple кортеж A tuple plays the same role as a “row” or a “record”. The number of tuples in a space is unlimited. Tuples in Tarantool are stored as MsgPack arrays.    
Tarantool Tarantool НЕ ПЕРЕВОДИТЬ    
primary index первичный индекс The first index defined on a space is called the primary key index, and it must be unique. All other indexes are called secondary indexes, and they may be non-unique. https://www.tarantool.io/en/doc/latest/book/box/data_model/#indexes    
fiber файбер A fiber is a set of instructions which are executed with cooperative multitasking. Fibers managed by the fiber module are associated with a user-supplied function called the fiber function. https://www.tarantool.io/en/doc/latest/reference/reference_lua/fiber/#fibers    
Tarantool garbage collector сборщик мусора в Tarantool A garbage collector fiber runs in the background on the master storages of each replica set. It starts deleting the contents of the bucket in the GARBAGE state part by part. Once the bucket is empty, its record is deleted from the _bucket system space. https://www.tarantool.io/en/doc/latest/reference/reference_rock/vshard/vshard_admin/#garbage-collector    
Lua garbage collector сборщик мусора на Lua Lua manages memory automatically by running a garbage collector from time to time to collect all dead objects (that is, objects that are no longer accessible from Lua). https://www.lua.org/manual/5.1/manual.html#2.10    
storage engine движок базы данных A storage engine is a set of very-low-level routines which actually store and retrieve tuple values. https://www.tarantool.io/en/doc/latest/book/box/engines/    
thread поток A thread of execution is the smallest sequence of programmed instructions that can be managed independently by a scheduler, which is typically a part of the operating system.    
Lua application Lua-приложение, приложение на языке Lua Tarantool’s native language for writing applications is Lua.    
memtx memtx      
instance экземпляр      
implicit casting неявное приведение типов      
database база данных      
Release policy Релизная политика A set of rules for releasing and naming new distributions of Tarantool: where we add new features and where we don’t, how we give them numbers, what versions are suitable to use in production.    
field поле Fields are distinct data values, contained in a tuple. They play the same role as «row columns» or «record fields» in relational databases.    
leader election выборы лидера (in a replica set, by the Raft algorithm)    
replica set набор реплик      
heartbeat контрольный сигнал      
functionality функциональность      
log журнал      
node узел      
follower реплика      
small allocator аллокатор small   https://github.com/tarantool/small  
patch патч      
breaking change критическое изменение      
parser парсер      
UUID UUID      
data type тип данных      
alias алиас   или псевдоним?  
push выполнить push      
MVCC (механизм) MVCC      
dirty read «грязное чтение»   в кавычках  
snapshot снимок (данных)      
keywords ключевые слова      
identifier имя, идентификатор      
clause предложение, блок (SQL) A clause in SQL is a part of a query that lets you filter or customizes how you want your data to be queried to you.    
expression выражение      
predicate предикат (SQL) Predicates, which specify conditions that can be evaluated to SQL three-valued logic (3VL) (true/false/unknown) or Boolean truth values and are used to limit the effects of statements and queries, or to change program flow.    
query запрос (SQL) Queries retrieve the data based on specific criteria. A query is a statement that returns a result set (possibly empty).    
result set результат запроса (SQL) An SQL result set is a set of rows from a database, as well as metadata about the query such as the column names, and the types and sizes of each column. A result set is effectively a table.    
statement инструкция (SQL) A statement is any text that the database engine recognizes as a valid command. (SQL) Любой текст, который распознаётся движком БД как команда. Инструкция состоит из ключевых слов и выражений языка SQL, которые предписывают Tarantool выполнять какие-либо действия с базой данных.  
    Tarantool: A statement consists of SQL-language keywords and expressions that direct Tarantool to do something with a database. https://www.tarantool.io/en/doc/latest/reference/reference_sql/sql_user_guide/#statements»    
batch пакет (инструкций) (SQL) A series of SQL statements sent to the server at once is called a batch. (SQL) Серия SQL-инструкций (statements), отправляемая на сервер вместе  
production configuration конфигурация производственной среды      
deployment развертывание Transforming a mechanical, electrical, or computer system from a packaged to an operational state. IT infrastructure deployment typically involves defining the sequence of operations or steps, often referred to as a deployment plan, that must be carried to deliver changes into a target system environment.    
roll back отменить   транзакцию  
deploy to production   IT infrastructure deployment typically involves defining the sequence of operations or steps, often referred to as a deployment plan, that must be carried to deliver changes into a target system environment. Production environment is a setting where software and other products are actually put into operation for their intended uses by end users    
operations эксплуатация (DevOps) Information technology operations, or IT operations, are the set of all processes and services that are both provisioned by an IT staff to their internal or external clients and used by themselves, to run themselves as a business.    
to deploy   Transforming a mechanical, electrical, or computer system from a packaged to an operational state. IT infrastructure deployment typically involves defining the sequence of operations or steps, often referred to as a deployment plan, that must be carried to deliver changes into a target system environment.    
deployment plan   A sequence of operations or steps that must be carried to deliver changes into a target system environment.    
production environment производственная среда Production environment is a term used mostly by developers to describe the setting where software and other products are actually put into operation for their intended uses by end users.    
failover восстановление после сбоев In computing and related technologies such as networking, failover is switching to a redundant or standby computer server, system, hardware component or network upon the failure or abnormal termination of the previously active application, server, system, hardware component, or network.    
directory директория      
bucket сегмент      
select выберите, выбрать To select a checkbox    

Localization guidelines

Use this guide when localizing Tarantool into Russian.

Tone of voice

General voice

We address IT specialists fairly knowledgeable in their respective fields. The goal of our translations is to help these people understand how to use Tarantool. Think of us as their colleagues and address them as such. Be professional but friendly. Don’t command or patronize. Use colloquial speech but avoid being too familiar. It’s all about the golden mean.

Gender neutrality

Use gender-neutral expressions like «сделать самостоятельно» instead of «сделать самому», etc.

Term choice

Though not all of our readers may be fluent in English, they write in English-based programming languages and are used to seeing error messages in English. Therefore, if they see an unfamiliar and/or more archaic Russian term for a familiar concept, they might have trouble correlating them.

We don’t want our audience to feel confused, so we prefer newer terms. We also provide the English equivalent for a term if it is used in the article for the first time.

If you feel like an older Russian term may sound more familiar for a part of the audience (for example, those with a math background), consider adding it in parentheses along with the English equivalent. Don’t repeat the parentheses throughout the text. A similar rule applies to introducing terms in Tarantool documentation.

Term choice examples

  First time All following times
state machine машина состояний (конечный автомат, state machine) машина состояний
write-ahead log; WAL журнал упреждающей записи (write-ahead log, WAL) журнал упреждающей записи; WAL; журнал WAL (using a descriptor)

Best practices

Be creative

Please avoid word-for-word translations. Let the resulting text sound as though it was originally written in Russian.

Less is more

Be concise and don’t repeat yourself. Fewer words are the best option most of the time.

Don’t Do
Профиль доступа можно назначить для любой роли пользователя, созданной администратором. А к ролям по умолчанию привязать профили доступа не получится, поскольку такие роли редактировать нельзя. Профиль доступа можно назначить для любой роли пользователя, созданной администратором. Исключение составляют роли по умолчанию, поскольку их нельзя редактировать.

Topic and focus

Avoid English word order.

The Russian speech is structured with topic and focus (тема и рема). The topic is the given in the sentence, something we already know. The focus is whatever new/important information is provided in the sentence about the topic. In written Russian, the focus most often stands at the end of the sentence, while in English, sentences may start with it.

It is recommended to use systemd for managing the application instances and accessing log entries. Для управления экземплярами приложения и доступа к записям журнала рекомендуется использовать systemd.
Do not specify working directories of the instances in this configuration. Не указывайте в этой конфигурации рабочие директории экземпляров.

No bureaucratese

Avoid overly formal, bureaucratic language whenever possible. Prefer verbs over verbal nouns, and don’t use «являться» and «осуществляться» unless it’s absolutely necessary.

To learn how to clear your Russian texts of bureaucratese, check Timur Anikin’s training «The Writing Dead».

Don’t Do
Сообщение исчезнет, как только вы покинете данную страницу. Сообщение исчезнет, как только вы покинете страницу.
Проверка истечения срока действия паролей производится раз в 30 минут. Раз в 30 минут система проверяет, не истек ли срок действия паролей.

Consistency

Use one term for one concept throughout the article. For example, only translate production as «производственная среда» and not as «эксплуатационная среда» throughout your article. It’s not about synonyms, but about terms: we don’t want people to get confused.

Avoid elliptical sentences

  Don’t Do
Defaults to root. По умолчанию — root. Значение по умолчанию — root.

Pronoun collocations

Do all the pronouns point to the exact nouns you want them to?

Example (how not to): Прежде чем добавить запись в конфигурацию, укажите к ней путь.

In the example, it is not quite clear what «к ней» means – to the record or to the configuration. For more on this issue, check out the writers“ reference at «Ошибкариум».

Be critical towards your text

Don’t forget to proofread your translation. Check your text at least twice.

Be nice to your peers

If you review others’ translations, be gentle and kind. Everyone makes mistakes, and nobody likes to be punished for them. You can use phrasings like «I suggest» or «it’s a good idea to… .»

Defining and using terms

What are concepts and terms

To write well about a certain subject matter, one needs to know its details and use the right, carefully selected words for them. These details are called concepts, and the words for them are called terms.

concept

A concept is the idea of an object, attribute, or action. It is independent of languages, audience, and products. It just exists.

For example, a large database can be partitioned into smaller instances. Those instances are easier to operate, and their throughput often exceeds the throughput of a single large database instance. The instances can exchange data to keep it consistent between them.

term

A term is a word explicitly selected by the authors of a particular text to denote a concept in a particular language for a particular audience.

For example, in Tarantool, we use the term «[database] sharding» to denote the concept described in the previous example.

Use preferred terms

The purpose of using terms is writing concisely and unambiguously, which is good for the readers. But selecting terms is hard. Often, the community favors two or more terms for one concept, so there’s no obvious choice. Selecting and consistently using any of them is much better than not making a choice and using a random term every time. This is why it’s also helpful to restrict the usage of some terms explicitly.

restricted term

A restricted term is a word that the authors explicitly prohibited to use for denoting a concept. Such a word is sometimes used as a term for the same concept elsewhere – in the community, in books, or in other product documentation. Sometimes this word is used to denote a similar but different concept. In this case, the right choice of terms helps us differentiate between concepts.

For example, in Tarantool, we don’t use the term «[database] segmentation» to denote what we call «database sharding.» Nevertheless, other authors might do so. We also use the term «[database] partitioning» to denote a wider concept, which includes sharding among other things.

Define terms by explaining concepts

We always want to document definitions for the most important concepts, as well as for concepts unique to Tarantool.

Define every term in the document that you find most appropriate for it. You don’t have to create a dedicated glossary page containing all the definitions.

To define a term, use the glossary directive in the following way:

..  glossary::

    term
        definition text

    term2
        definition text

There can be several glossary directives in a Sphinx documentation project and even in a single document. This page has two of them, for example.

The Sphinx documentation has an extensive glossary that can be used as a reference.

Introduce terms on first entry

When you use a term in a document for the first time, define it and provide synonyms, a translation, examples, and/or links. It will help readers learn the term and understand the concept behind it.

  1. Define the term or give a link to the definition.

    Database sharding is a type of horizontal partitioning.

    To give a link to the definition, use the term role:

    For example, this is a link to the definition of :term:`concept`.
Like any rST role, it can have :term:`custom text <concept>`.

    The resulting output will look like this:

    For example, this is a link to the definition of concept. Like any rST role, it can have custom text.

    With acronyms, you can also use the abbr role:

    Delete the corresponding :abbr:`PVC (persistent volume claim)`...

    It produces a tooltip link: PVC.

  2. Provide synonyms, including the restricted terms. Only do it on the first entry of a term.

    Database sharding (also known as …) is a type of…

  3. When writing in Russian, it’s good to add the corresponding English term. Readers may be more familiar with it or can search it online.

    Шардирование (сегментирование, sharding) — это…

  4. Give examples or links to extra reading where you can.

Markup reference

Tarantool documentation is built via the Sphinx engine and is written in reStructuredText. This section will guide you through our typical documentation formatting cases.

Оглавление:

General syntax guidelines

Basic syntax

Paragraphs contain text and may contain inline markup: emphasis, strong emphasis, interpreted text, inline literals.

Text can be organized in bullet-lists:

*   This is a bullet list.

*   Bullets can be "*", "+", or "-".

    -   Lists can be nested. And it is good to indent them with 4 spaces.

or in enumerated lists:

1.  This is an enumerated list.

2.  Tarantool build uses only arabic numbers as enumerators.

#.  You can put #. instead of point numbers and Sphinx will
    recognize it as an enumerated list.

Перенос текста

It’s good practice to wrap lines in documentation source text. It makes source better readable and results in lesser git diff’s. The recommended limit is 80 characters per line for plain text.

In new documents, try to wrap lines by sentences, or by parts of a complex sentence. Don’t wrap formatted text if it affects rST readability and/or HTML output. However, wrapping with proper indentation shouldn’t break things.

Отступы

In rST, indents play exactly the same role as in Python: they denote object boundaries and nesting.

For example, a list starts with a marker, then come some spaces and text. From there, all lines relating to that list item must be at the same indentation level. We can continue the list item by creating a second paragraph in it. To do that we have to leave it at the same level.

We can put a new object inside: another list, or a block of code. Then we have to indent 4 more spaces.

It’s best if all indents are multiples of 4 spaces, even in lists. Otherwise the document is not consistent. Also, it is much easier to put indents with tabs than manually.

Note that you have to use two or three spaces instead of one. It is allowed in rST markup:

|...|...|...|...
*   unordered list
#.  ordered list
..  directive::
|...|...|...|...

Пример:

|...|...|...|...
#.  List item 1.
    Paragraph continues.

    Second paragraph.

#.  List item 2.

    *   Nested list item.

        ..  code-block:: bash

            # this code block is in a nested list item

    *   Another nested list item.
|...|...|...|...

Resulting output:

  1. List item 1. Paragraph continues.

    Second paragraph.

  2. List item 2.

    • Nested list item.

      # this code block is in a nested list item

    • Another nested list item.

Добавление комментариев

Sometimes we may need to leave comments in an rST file. To make Sphinx ignore some text during processing, use the following per-line notation with .. // as the comment marker:

.. // здесь комментарий

The starting characters .. // do not interfere with the other rST markup, and they are easy to find both visually and using grep. To find comments in source files, go ahead with something like this:

$ grep -n "\.\. //" doc/reference/**/*.rst
doc/reference/reference_lua/box.rst:47:.. // moved to "User Guide > 5. Server administration":
doc/reference/reference_lua/box.rst:48:.. // /book/box/triggers
...

If you’re working with PyCharm or other similar IDE, links in the console will be clickable and will lead right to the source file and string. Check it out!

clickable links in the console

These comments don’t work properly in nested documentation, though. For example, if you leave a comment in module -> object -> method, Sphinx ignores the comment and all nested content that follows in the method description.

Headings

Heading markup

We use the following markup for headings:

Level 1 heading
===============

Level 2 heading
---------------

Level 3 heading
~~~~~~~~~~~~~~~

Level 4 heading
^^^^^^^^^^^^^^^

The underlining should be exactly the same length as the heading text above it. Mismatching length will result in a build warning.

Sphinx allows using other characters and styles to format headings. Indeed, using this markup consistently helps us better reuse and move content. It also helps us recognize the heading level immediately without reading the whole document and calculating levels.

If you’re going to make a 4th or 5th level heading, you probably need to split the document instead.

Title headings

The top-level heading of each document plays the important role of a document title. Title’s text is used in several places:

ard to navigate in a hierarchy of more than three heading levels.

Tables

Tables are very useful and rST markup offers different ways to create them.

We prefer list-tables because they allow you to put as much content as you need without painting ASCII-style borders:

..  container:: table

    ..  list-table::
        :widths: 25 75
        :header-rows: 1

        *   -   Name
            -   Use

        *   -   :doc:`/reference/reference_lua/box_ctl/wait_ro`
            -   Wait until ``box.info.ro`` is true

This is how the table will look like:

Имя Назначение
box.ctl.wait_ro() Дождаться, пока не будет выполнено box.info.ro

Notice that we use * and then - in tables because it is more readable when rows and columns marked differently.

Writing about code

When writing articles, you need to format code specially, separating it from other text. This document will guide you through typical cases when it is recommended to use code highlighting.

Defining what code is

In general, code is any text, processed by a machine. It is also probably code if the expression contains characters that ordinary words do not have, such as _, {}, [ ], .. Also, you should format the expression as code if it fits at least one of the items in the list below:

Items we don’t format as code:

Keep in mind that grammar doesn’t apply to code, even inline.

Code blocks and inline code

If you have to choose between inline code and code block highlighting, pay attention to the following guidelines:

Code snippets

Use code blocks when you have to highlight multiple lines of code. Also, use it if your code snippet contains a standalone element that is not a part of the article’s text.

For code snippets, we use the code-block:: language directive. You can enable syntax highlighting if you specify the language for the snippet. The most commonly used highlighting languages are:

  • tarantoolsession – interactive Tarantool session, where command lines start with tarantool> prompt.
  • console – interactive console session, where command lines start with $ or #.
  • lua, bash or c for programming languages.
  • text for cases when we want the code block to have no highlighting.

Sphinx uses the Pygments library for highlighting source code. For a complete list of possible languages, see the list of Pygments lexers.

For example, a code snippet in Lua:

..  code-block:: lua

    for page in paged_iter("X", 10) do
      print("New Page. Number Of Tuples = " .. #page)
      for i=1,#page,1 do print(page[i]) end
    end

Lua syntax is highlighted in the output:

for page in paged_iter("X", 10) do
  print("New Page. Number Of Tuples = " .. #page)
  for i=1,#page,1 do print(page[i]) end
end

Note that in code blocks you can write comments and translate them:

..  //Here is the first comment.
..  //Here is the second comment.

Inline code

Use inline code when you need to wrap a short snippet of code in text, such as variable name or function definition. Keep in mind that inline code doesn’t have syntax highlighting.

To format some inline text as code, enclose it with double ` characters or use the :code: role:

*   Formatting code with backticks: ``echo "Hello world!"``.

*   Formatting code with a role: :code:`echo "Hello world!"`.

Both options produce the same output:

  • Formatting code with backticks: echo "Hello world!".
  • Formatting code with a role: echo "Hello world!".

Notes on using inline-code

  • If you have expressions such as id==4, you should format the whole expression as code inline. Also, you can use the words «equals», «doesn’t equal» or other similar words without formatting expression as code. Both variants are correct.
  • Inline code can be used to highlight expressions that are hard to read, for example, words containing il, Il or O0.

Highlighting variables in code

If you need to mark up a placeholder inside code inline, use the :samp: or our custom :extsamp: role, like this:

:samp:`{space_object}:insert(\\{ffi.cast('double', {value})\\})`

:extsamp:`{*{space_object}*}:insert({ffi.cast('double', {**{value}**})})`

And you will get this:

space_object:insert({ffi.cast('double', value)})

space_object:insert({ffi.cast('double', value)})

Notice two backslashes before the curly brackets in the first line. They are needed to escape curly brackets from Lua syntax.

As you can see, :extsamp: extends the abilities of :samp:. It allows you to highlight placeholders in both italics and bold and avoid escaping curly brackets. :extsamp: has the following syntax:

If you need to mark up a placeholder in code block, use the following syntax:

..  cssclass:: highlight
..  parsed-literal::

    :samp:`box.space.{space-name}:create_index('{index-name}')`

The output will look like this:

box.space.space-name:create_index('index-name')

Formatting file and directory names

If you need to highlight some file standalone name or path to file in text, use the :file: role. You can use curly braces inside this role to mark up a replaceable part:

:file:`/usr/bin/example.py`

:file:`/usr/{dirname}/example.py`

:file:`/usr/{dirname}/{filename.ext}`

And you will get this:

/usr/bin/example.py

/usr/dirname/example.py

/usr/dirname/filename.ext

Referring to GUI elements

To mention a GUI element, use the :guilabel: directive:

Click the :guilabel:`OK` button.

Admonitions

Sometimes you need to highlight a piece of information. For this purpose we use admonitions.

In Tarantool we have 3 variants of css-style for admonitions:

The docutils documentation offers many more variants for admonitions, but for now these three are enough for us. If you think that it is time to create the new style for some of these types, feel free to contribute or contact us to create a task.

Documenting the API

This document contains general guidelines for describing the Tarantool API, as well as examples and templates.

Style

Please write as simply as possible. Describe functionality using short sentences in the present simple tense. A short sentence consists of no more than two clauses. Consider using LanguageTool or Grammarly to check your English. For more style-related specifics, consult the Language and style section.

Indicating the version

For every new module, function, or method, specify the version it first appears in.

For a new parameter, specify the version it first appears in if this parameter is a «feature» and the version it’s been introduced in differs from the version introducing the function/method and all other parameters.

To specify the version, use the following Sphinx directive:

Since :doc:`2.10.0 </release/2.10.0>`.
This is a link to the release notes on the Tarantool documentation website.

The result looks like this:

Since Tarantool 2.10.0. This is a link to the release notes on the Tarantool documentation website.

Language of the general description

Use one of the two options:

Checklist

Each list item is a characteristic to be described. Some items can be optional.

Function or method

See module function example, class method example.

Function and method parameters

If the parameter is optional, make sure it is enclosed in square brackets in the function declaration (in the «heading»). Do not mark parameters additionally as «optional» or «required»:

..  function:: format(URI-components-table[, include-password])

    Construct a URI from components.

    :param URI-components-table: a series of ``name:value`` pairs, one for each component
    :param include-password: boolean. If this is supplied and is ``true``, then
                             the password component is rendered in clear text,
                             otherwise it is omitted.

Configuration parameters

Configuration parameters are not to be confused with class and method parameters. Configuration parameters are passed to Tarantool via the command line or in an initialization file. You can find a list of Tarantool configuration parameters in the configuration reference.

See configuration parameter example.

Documenting possible errors

In the «Possible errors» section of a function or class method, consider explaining what happens if any parameter hasn’t been defined or has the wrong value.

Examples and templates

Module functions

We use the Sphinx directives .. module:: and .. function:: to describe functions of Tarantool modules:

..  module:: fiber

..  function:: create(function [, function-arguments])

    Create and start a fiber. The fiber is created and begins to run immediately.

    :param function: the function to be associated with the fiber
    :param function-arguments: what will be passed to function.

    :return: created fiber object
    :rtype: userdata

    **Example:**

    ..  code-block:: tarantoolsession

        tarantool> fiber = require('fiber')
        ---
        ...
        tarantool> function function_name()
                 >   print("I'm a fiber")
                 > end
        ---
        ...
        tarantool> fiber_object = fiber.create(function_name); print("Fiber started")
        I'm a fiber
        Fiber started
        ---
        ...

The resulting output looks like this:

fiber.create(function[, function-arguments])

Create and start a fiber. The fiber is created and begins to run immediately.

Параметры:
  • function – the function to be associated with the fiber
  • function-arguments – what will be passed to function.
Return:

created fiber object
Rtype:

userdata

Example:

tarantool> fiber = require('fiber')
---
...
tarantool> function function_name()
         >   print("I'm a fiber")
         > end
---
...
tarantool> fiber_object = fiber.create(function_name); print("Fiber started")
I'm a fiber
Fiber started
---
...

Class methods and data

Methods are described similarly to functions, but the .. class:: directive, unlike .. module::, requires nesting.

As for data, it’s enough to write the description, the return type, and an example.

Here is the example documentation describing the method and data of the index_object class:

..  class:: index_object

    ..  method:: get(key)

        Search for a tuple :ref:`via the given index <box_index-note>`.

        :param index_object index_object: :ref:`object reference
                                          <app_server-object_reference>`
        :param scalar/table      key: values to be matched against the index key

        :return: the tuple whose index-key fields are equal to the passed key values
        :rtype:  tuple

        **Possible errors:**

        * No such index
        * Wrong type
        * More than one tuple matches

        **Complexity factors:** index size, index type.
        See also :ref:`space_object:get() <box_space-get>`.

        **Example:**

        ..  code-block:: tarantoolsession

            tarantool> box.space.tester.index.primary:get(2)
            ---
            - [2, 'Music']
            ...

    ..  data:: unique

        True if the index is unique, false if the index is not unique.

        :rtype: boolean

        ..  code-block:: tarantoolsession

            tarantool> box.space.tester.index.primary.unique
            ---
            - true
            ...

And the resulting output looks like this:

object index_object
index_object:get(key)

Search for a tuple via the given index.

Параметры:
Return:

the tuple whose index-key fields are equal to the passed key values
Rtype:

tuple

Possible errors:

  • No such index
  • Wrong type
  • More than one tuple matches

Complexity factors: index size, index type. See also space_object:get().

Example:

tarantool> box.space.tester.index.primary:get(2)
---
- [2, 'Music']
...
index_object.unique

True if the index is unique, false if the index is not unique.

Rtype:boolean 
tarantool> box.space.tester.index.primary.unique
---
- true
...

Configuration parameters

Example:

.. _cfg_basic-vinyl_dir:

.. confval:: vinyl_dir

    Since version 1.7.1.

    A directory where vinyl files or subdirectories will be stored. Can be
    relative to :ref:`work_dir <cfg_basic-work_dir>`. If not specified, defaults
    to ``work_dir``.

    |
    | Type: string

Result:

vinyl_dir

Since version 1.7.1.

A directory where vinyl files or subdirectories will be stored. Can be relative to work_dir. If not specified, defaults to work_dir.


Type: string

Images

Images are useful in explanations of concepts and structures. When you introduce a term or describe a structure of multiple interconnected parts (such as a cluster), consider illustrating it with a diagram. If you are explaining how to use a GUI, check if a screenshot can make the doc clearer.

Note that illustrations should complement the text, not replace it. Even with an image, the text should be enough for readers to understand the topic.

Don’t overuse images: they are harder to support than text. Use them only if they bring an obvious benefit.

Diagrams

There is a basic set of diagram elements – blocks, arrows, and other – to use in Tarantool docs. It is stored in this Miro board. It also provides basic rules for creating diagrams.

Size

There are two sizes of diagram elements:

  • M – bigger elements to use in diagrams with a small number of elements.
  • S – smaller elements to use in diagrams with a big number of elements.

Avoid changing the size of diagram elements unless it’s absolutely necessary.

The diagrams should have the same width. This guarantees that their elements have the same size on pages. The examples in the Miro board have frames of the right width. Copy the frame and and place your diagram in it without changing the frame width.

Exporting

To save the diagram to a file:

  1. Make the frame transparent so that it isn’t shown in the resulting image (set its color to «no color»).
  2. Select all elements together with the frame and click Copy as image in the context menu (under the three dots). The image will be copied to the clipboard.
  3. Paste the image from the clipboard to any graphic editor, for example, GIMP.
  4. Remove the Miro logo in the bottom right corner.
  5. Export/save the image to PNG.

Screenshots

Take screenshots with any tool you like.

Ensure screenshot consistency on the page:

Markup

Insert the images using the image directive:

..  image:: images/example_diagram.png
    :alt: Example diagram alt text

Result:

Example diagram alt text

Building Tarantool Docs

How to build Tarantool documentation using Docker

See Docker

Prepare for work

First of all, pull the image for building the docs.

docker pull tarantool/doc-builder:fat-4.3

Next, initialize a Makefile for your OS:

docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "cmake ."

Update submodules and generate documentation sources from code

A big part of documentation sources comes from several other projects, connected as Git submodules. To include their latest contents in the docs, run these two steps.

  1. Update the submodules:

    git submodule update --init
git fetch --recurse-submodules
git submodule update --remote --checkout

    This will initialize Git submodules and update them to the top of the stable branch in each repository.

    git submodule update can sometimes fail, for example, when you have changes in submodules“ files. You can reinitialize submodules to fix the problem.

    Caution: all untracked changes in submodules will be lost!

    git submodule deinit -f .
git submodule update --init

    Note that there’s an option to update submodule repositories with a make command. However, it’s intended for use in a CI environment and not on a local machine.

    docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make pull-modules"

  2. Build the submodules content:

    docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make build-modules"

    This command will do two things:

    1. Generate documentation source files from the source code
    2. Copy these files to the right places under the ./doc/ directory.

    If you’re editing submodules locally, repeat this step to view the updated results.

Now you’re ready to build and preview the documentation locally.

Build and run the documentation on your machine

When editing the documentation, you can set up a live-reload server. It will build your documentation and serve it on 127.0.0.1:8000. Every time you make changes in the source files, it will rebuild the docs and refresh the browser page.

docker run --rm -it -p 8000:8000 -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make autobuild"

First build will take some time. When it’s done, open 127.0.0.1:8000 in the browser. Now when you make changes, they will be rebuilt in a few seconds, and the browser tab with preview will reload automatically.

You can also build the docs manually with make html, and then serve them using python3 built-in server:

docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make html"
docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make html-ru"
python3 -m http.server --directory output/html

or python2 built-in server:

cd output/html
python -m SimpleHTTPServer

then go to localhost:8000 in your browser.

There are other commands which can run in the tarantool/doc-builder container:

docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make html"
docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make html-ru"
docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make singlehtml"
docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make singlehtml-ru"
docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make pdf"
docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make pdf-ru"
docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make json"
docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make json-ru"
docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make epub"
docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make epub-ru"
docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make update-po"

Linkcheck

There’s a specific build mode which checks internal and external links instead of producing a document.

docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make linkcheck"

If you need to save the linkcheck’s report in a file, you can use the following trick:

docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make linkcheck" 2>&1 | tee linkcheck.log

Here 2>&1 redirects the stderr output to stdout, and then tee both shows in on screen and writes to a file.

Vale

Tarantool documentation uses the Vale linter for checking grammar, style, and word usage. Its configuration is placed in the vale.ini file located in the root project directory.

To enable RST support in Vale, you need to install Sphinx. Then, you can enable Vale integration in your IDE, for example:

Localization

Terms:

To update the translation files, run the make update-po task:

docker run --rm -it -v $(pwd):/doc tarantool/doc-builder:fat-4.3 sh -c "make update-po"

Translate the strings in the updated files and then commit the changes.

How to contribute

To contribute to documentation, use the REST format for drafting and submit your updates as a pull request via GitHub.

To comply with the writing and formatting style, use the guidelines provided in the documentation, common sense and existing documents.

Notes:

Sphinx-build warnings reference

This document will guide you through the warnings that can be raised by Sphinx while building the docs.

Below are the most frequent warnings and the ways to solve them.

Bullet list ends without a blank line; unexpected unindent

Similar warning: Block quote ends without a blank line; unexpected unindent

Пример:

*   The last point of bullet list
This text should start after a blank line

Решение:

*   The last point of bullet list

This text should start after a blank line

Could not lex literal_block as «…». Highlighting skipped

This warning means that there’s a code-block with an unknown lexer. Most probably, it’s a typo. Check out the full list of Pygments lexers for the right spelling.

Пример:

..  code-block:: cxx

    // some code here

Решение:

..  code-block:: cpp

    // some code here

However, sometimes there’s no appropriate lexer or the code snippet can’t be lexed properly. In that case, use code-block:: text.

Duplicate explicit target name: «…»

Пример:

*   `Install <https://git-scm.com/book/en/v2/Getting-Started-Installing-Git>`_
    ``git``, the version control system.

*   `Install <https://linuxize.com/post/how-to-unzip-files-in-linux/>`_
    the ``unzip`` utility.

Решение:

Sphinx-builder raises warnings when we call different targets the same name. Sphinx developers recommend using double underlines __ in such cases to avoid this.

*   `Install <https://git-scm.com/book/en/v2/Getting-Started-Installing-Git>`__
    ``git``, the version control system.

*   `Install <https://linuxize.com/post/how-to-unzip-files-in-linux/>`__
    the ``unzip`` utility.

Document isn’t included in any toctree

This warning means that you forgot to put the document name in the toctree.

Решение:

If you don’t want to include the document in a toctree, place the :orphan: directive at the top of the file. If this file is already included somewhere or reused, add it to the _includes directory. Sphinx ignores everything in this directory because we list it among exclude_patterns in conf.py.

Duplicate label «…», other instance in «…/…/…»

This happens if you include the contents of a file into another file, when the included file has tags in it. In this, Sphinx thinks the tags are repeated.

Решение:

As in the previous case, add the file to _includes or avoid using tags in it.

Toctree contains reference to nonexisting document „…“

Пример:

This may happen when you refer to a wrong path to a document.

Решение:

Check the path.

If the path points to a submodule, check that you’ve built the submodules content before building docs.

Unexpected indentation

The reStructuredText syntax is based on indentation, much like in Python. All lines in a block of content must be equally indented. An increase or decrease in indentation denotes the end of the current block and the beginning of a new one.

Пример:

Note: In the following examples, dots stand for indentation spaces. For example, |..| denotes a two-space indentation.

|..|* (Engines) Improve dump start/stop logging. When initiating memory dump, print
how much memory is going to be dumped, the expected dump rate, ETA, and the recent
write rate.

Решение:

*|...|(Engines) Improve dump start/stop logging. When initiating memory dump, print
|....|how much memory is going to be dumped, the expected dump rate, ETA, and the recent
|....|write rate.

См. также:

Unknown document

Пример:

:doc:`reference/reference_lua/box_space/update`

Решение:

Sphinx did not recognize the file path correctly due to a missing slash at the beginning, so let’s just put it there:

:doc:`/reference/reference_lua/box_space/update`

Documentation infrastructure

This section of the documentation guidelines discusses some of the support activities that ensure the correct building of documentation.

Adding submodules

The documentation source files are mainly stored in the documentation repository. However, in some cases, they are stored in the repositories of other Tarantool-related products or modules, such as Monitoring.

If you are working with source files from a product or module repository, add that repository as a submodule to the documentation repository and configure other necessary settings. This will ensure that the entire body of Tarantool documentation, presented on the official website, is built properly.

Here is how to do that:

1. Add a submodule

First, we need to add the repository with content source files as a submodule.

  1. Make sure you are in the root directory of the documentation repository.

  2. In the ./modules directory, add the new submodule:

    cd modules
git submodule add https://<path_to_submodule_repository>
cd ..

  3. Check that the new submodule is in the .gitmodules file, for example:

[submodule "modules/metrics"]
   path = modules/metrics
   url = https://github.com/tarantool/metrics.git

2. Update build_submodules.sh

Now define what directories and files are to be copied from the submodule repository to the documentation repository before building documentation. These settings are defined in the build_submodules.sh file in the root directory of the documentation repository.

Here are some real submodule examples that show the logic of the settings.

metrics

The content source files for the metrics submodule are in the ./doc/monitoring directory of the submodule repository. In the final documentation view, the content should appear in the Monitoring chapter (https://www.tarantool.io/en/doc/latest/book/monitoring/).

To make this work:

  • Create a directory at ./doc/book/monitoring/.
  • Copy the entire content of the ./modules/metrics/doc/monitoring/ directory to ./doc/book/monitoring/.

Here are the corresponding lines in build_submodules.sh:

monitoring_root="${project_root}/modules/metrics/doc/monitoring" #
monitoring_dest="${project_root}/doc/book"

mkdir -p "${monitoring_dest}"
yes | cp -rf "${monitoring_root}" "${monitoring_dest}/"

The ${project_root} variable is defined earlier in the file as project_root=$(pwd). This is because the documentation build has to start from the documentation repository root directory.

3. Update .gitignore

Finally, add paths to the copied directories and files to .gitignore.

Git workflow

Branching

Use one branch for a single task, unless you’re fixing typos or markup on several pages. Long commit histories are hard to manage and sometimes end up stale.

Start a new branch from the last commit on latest. Make sure to update your local version of latest with git pull. Otherwise, you may have to rebase later.

Name your branch so it’s clear what you’re doing. Examples:

Важно

It is not recommended to submit PRs to the documentation repository from forks. Because of a GitHub failsafe mechanism, it is impossible to view changes from a fork on the development website.

Creating branches directly in the repository results in a more convenient workflow.

Linking issues and PRs

When a PR is linked to an issue:

Specify the issue(s) you want to close in the description of your PR. GitHub will connect them if you use specific keywords. Here are some of them:

If your PR closes more than one issue, mention each of them:

Resolves #1300, resolves #1234, resolves tarantool/doc#100

Commit messages

Good examples

  • git commit -m "Expand section on msgpack"
  • git commit -m "Add details on IPROTO_BALLOT"
  • git commit -m "Create new structure"
  • git commit -m "Improve grammar"

Bad examples

  • git commit -m "Fix gh-2007, second commit"
  • git commit -m “Changed the file box_protocol.rst”
  • git commit -m "added more list items"

Selecting a reviewer

Ideally, a PR should have two reviewers: a subject matter expert (SME) and a documentarian. The SME checks the facts, and the documentarian checks the language and style.

If you’re not sure who the SME for an issue is, try the following:

Merging

Merge when your document is ready and good enough. For external contributors, merging is blocked until a reviewer’s approval.

Руководство по написанию кода на C

Для управления версиями мы используем Git. Разработки ведутся в ветке, используемой по умолчанию (сейчас master). Наш Git-репозиторий находится на GitHub, его можно выгрузить с помощью git clone git://github.com/tarantool/tarantool.git (анонимный пользователь получит доступ только для чтения).

Если у вас есть вопросы о внутреннем устройстве Tarantool, задайте их на StackOverflow или напрямую разработчикам Tarantool в Telegram.

Общие рекомендации

Стиль разработки проекта основан на стиле программирования ядра Linux.

Кроме того, мы даем дополнительные рекомендации, которые либо специфичны для Tarantool, либо отличаются от рекомендаций по программированию ядра Linux. Ниже приведен стиль программирования ядра Linux, переработанный с учетом особенностей разработки Tarantool.

Стиль программирования Tarantool

В этом документе описан приоритетный стиль программирования Tarantool для разработчиков и участников сообщества. Мы настаиваем на соблюдении этих правил, чтобы наш код был последовательным и понятным любому разработчику.

Глава 1: Отступы

Табуляция составляет 8 символов (8 символов табуляции, а не 8 пробелов), то есть отступы будут также составлять 8 символов. Появляются отступники, которые призывают делать отступы в 4 (или даже 2!) символа, а это сродни попытке округлить число Пи до 3.

Обоснование: Основная идея отступов состоит в том, чтобы показать, где начинается и заканчивается логический блок кода. Особенно если вы смотрите на один и тот же код в течение 20 часов, трудно не заметить пользу больших отступов.

Некоторые могут возразить, что отступ в 8 символов делает код слишком широким, особенно на 80-знаковой строке терминала. Ответ: Если вам понадобилось более трех уровней отступа, вы что-то делаете неправильно, и вам следует переписать этот участок.

Отступы в 8 символов облегчают чтение кода. Кроме того, по ним можно понять, когда у вас становится слишком много вложенных функций.

Лучше всего упростить несколько уровней отступов в операторе switch, выравнивая switch и его вспомогательные метки case в одном столбце вместо того, чтобы использовать двойные отступы для меток case, например:

switch (suffix) {
case 'G':
case 'g':
  mem <<= 30;
  break;
case 'M':
case 'm':
  mem <<= 20;
  break;
case 'K':
case 'k':
  mem <<= 10;
  /* fall through */
default:
  break;
}

Не размещайте несколько операторов на одной строке, если вам нечего скрывать:

if (condition) do_this;
  do_something_everytime;

И не размещайте несколько операторов присваивания на одной строке. Избегайте сложных выражений.

Пробелы используются только в комментариях и документации, но никогда — для отступов, и приведенный выше пример сломан намеренно.

Найдите достойный редактор и не оставляйте пробелы в конце строки.

Глава 2: Разрыв длинных строк

Смысл стиля программирования заключается в читаемости и удобстве сопровождения с использованием общедоступных средств.

Длина строк ограничена 80 символами, и этому следует уделить особое внимание. Для комментариев установлен тот же лимит в 80 символов.

Операторы длиной более 80 символов будут разбиты на логические части. Можно сделать исключение, если это значительно повысит читаемость и не скроет информацию. Последующие части значительно короче основной и сильно смещены вправо. То же относится к заголовкам функций с длинным списком аргументов.

Глава 3: Фигурные скобки и пробелы

Другая проблемой, которая всегда возникает в программировании на C, — размещение фигурных скобок. В отличие от отступов, есть несколько технических обоснований, чтобы выбрать один способ, а не другой, но всё же предпочтительно, как нам показали великие Керниган и Ричи, поместить открывающую скобку в конце строки, а закрывающую в начале новой строки:

if (x is true) {
  we do y
}

Это применимо ко всем блокам операторов без функций (if, switch, for, while, do), например:

switch (action) {
case KOBJ_ADD:
  return "add";
case KOBJ_REMOVE:
  return "remove";
case KOBJ_CHANGE:
  return "change";
default:
  return NULL;
}

И только в особенных случаях, а именно для функций, открывающая скобка размещается в начале следующей строки:

int
function(int x)
{
  body of function
}

Отступники по всему миру утверждали, что такая несогласованность … ну … несогласованна, но все здравомыслящие люди знают: (a) K&R правы, (б) K&R правы. Кроме того, функции в любом случае будут особенными (в C их нельзя вложить).

Обратите внимание, что за закрывающей скобкой на отдельной строке ничего нет; кроме тех случаев, когда за ней следует продолжение того же оператора, то есть while в do-операторе или else в if-операторе, например:

do {
  body of do-loop
} while (condition);

и

if (x == y) {
  ..
} else if (x > y) {
  ...
} else {
  ....
}

Обоснование: K&R.

Кроме того, обратите внимание, что такое расположение скобок также сводит к минимуму количество пустых (или почти пустых) строк без потери читаемости. Таким образом, поскольку новые строки на экране — это не возобновляемый ресурс (вспомним о 25-строчных экранах терминала), у вас будет больше пустых строк для комментариев.

Не используйте лишние фигурные скобки, если нужен всего один оператор.

if (condition)
  action();

и

if (condition)
  do_this();
else
  do_that();

Это не применимо, если только одна ветка условного оператора — это отдельный оператор. В последнем случае используйте фигурные скобки в обеих ветках:

if (condition) {
  do_this();
  do_that();
} else {
  otherwise();
}

Глава 3.1: Пробелы

В том, что касается пробелов, стиль программирования Tarantool зависит (в основном) от использования функции или ключевого слова. Используйте пробел после (большинства) ключевых слов. Значимые исключения: sizeof, typeof, alignof и __attribute__, — которые похожи на функции (и обычно используются с круглыми скобками, хотя они и не обязательны, как в объявлении sizeof info после struct fileinfo info;).

Итак, вставляйте пробелы после этих ключевых слов:

if, switch, case, for, do, while

но не после sizeof, typeof, alignof или __attribute__. Например:

s = sizeof(struct file);

Не добавляйте пробелы вокруг (внутри) выражений в круглых скобках. Этот пример неправильный:

s = sizeof( struct file );

Объявляя данных типа указателя или функцию, которая возвращает тип указателя, лучше использовать * рядом с именем данных или именем функции, а не рядом с именем типа. Примеры:

char *linux_banner;
unsigned long long memparse(char *ptr, char **retptr);
char *match_strdup(substring_t *s);

Добавляйте по одному пробелу вокруг (с каждой стороны) большинства знаков двухместных и трехместных операций, например, любое из следующих:

=  +  -  <  >  *  /  %  |  &  ^  <=  >=  ==  !=  ?  :

но не добавляйте пробелы после знаков одноместных операций:

&  *  +  -  ~  !  sizeof  typeof  alignof  __attribute__  defined

не нужны пробелы перед знаками одноместных операций увеличения или уменьшения постфикса:

++  --

не нужны пробелы после знаков одноместных операций увеличения или уменьшения префикса:

++  --

и не нужны пробелы вокруг знаков элементов структуры . и ->.

Не отделяйте оператор приведения от аргумента пробелом, например (ssize_t)inj->iparam.

Не оставляйте пробелы на концах строк. Некоторые редакторы с smart отступом вставляют пробелы в начале новых строк, поэтому вы можете сразу ввести следующую строку кода. Однако некоторые такие редакторы не удаляют пробелы, если вы не пишете там код, например, если вы оставите пустую строку. В результате имеем строки с пробелами в конце.

Git предупредит, если патчи содержат пробелы в конце строк, и может по желанию удалить пробелы за вас; однако, в серии патчей, это может привести к тому, что последующие патчи в серии не применятся, поскольку изменены контекстные строки.

Глава 4: Именование

C — это спартанский язык, и именование должно быть спартанским. В отличие от разработчиков на Modula-2 и Pascal, разработчики на языке C не используют забавные имена, такие как ThisVariableIsATemporaryCounter. Разработчик на языке C назвал бы такую переменную tmp, что намного легче написать и не сложнее понять.

ОДНАКО, хотя на имена со смешанным регистром смотрят неодобрительно, обязательным требованием будут описательные имена глобальных переменных. Назвать глобальную функцию foo — это оскорбление.

У ГЛОБАЛЬНЫХ переменных (которые надо использовать, только если без них нельзя обойтись) должны быть описательные имена, равно как и у глобальных функций. Если у вас есть функция, которая подсчитывает количество активных пользователей, нужно назвать ее count_active_users() или как-то похоже, не стоит называть ее cntusr().

Кодирование типа функции в названии (так называемая венгерская нотация) — это признак плохого тона, поскольку компилятор в любом случае знает типы и может их проверять, и это только путает программиста. Неудивительно, что MicroSoft делает глючные программы.

Имена ЛОКАЛЬНЫХ переменных должны быть короткими и точными. Если у вас есть счетчик случайных целых чисел, его следует называть i. Назвать его loop_counter непродуктивно, если нет никаких шансов, что его перепутают. Аналогично tmp может быть практически любой переменной, которая используется для хранения временного значения.

Если вы боитесь перепутать имена своих локальных переменных, у вас другая проблема, которая называется синдромом дисбаланса гормона роста функций. См. Главу 6 (Функции).

Для именования функций у нас есть такое правило:

  • new/delete для функций, которые выделяют + инициализируют и удаляют + освобождают объект,
  • create/destroy для функций, которые инициализируют/удаляют объект, но не занимаются управлением памятью,
  • init/free для функций, которые инициализируют/удаляют библиотеки и подсистемы.

Глава 5: Директива Typedef

Не используйте что-то вроде vps_t. Будет ошибкой использовать typedef для определения структур и указателей. Если вы видите в исходном коде

vps_t a;

что это означает? И наоборот, если говорится

struct virtual_container *a;

можно действительно понять, что такое a.

Многие думают, что typedef способствует читаемости. Это не так. Эту директиву нужно использовать для:

  1. Непрозрачных объектов (где typedef активно используется для сокрытия объекта).

    Пример: pte_t и другие непрозрачные объекты, доступ к которым можно получить с помощью соответствующих функций доступа.

    Примечание

    Непрозрачность и функции доступа сами по себе не слишком хороши. Мы используем их для pte_t и т. п., потому что на самом деле там нет никакой информации для скачивания.

  2. Явные целочисленные типы, где абстракция помогает не перепутать, int это или long.

    u8/u16/u32 — вполне нормальные typedef, хотя они больше подходят для пункта 4.

    Примечание

    Опять же — для этого должна быть причина. Если есть «unsigned long», нет причины вводить typedef unsigned long myflags_t;

    но если есть четкая причина, почему при определенных обстоятельствах может быть unsigned int, а в других случаях может быть unsigned long, то на здоровье — используйте typedef.

  3. Когда вы используете разрыв, чтобы буквально создать новый тип для проверки типов.

  4. Новые типы, идентичные стандартным типам C99, в определенных исключительных обстоятельствах.

    Хотя глазам и мозгу нужно лишь короткое время, чтобы привыкнуть к стандартным типам, например uint32_t, некоторые в любом случае возражают против их использования.

    При редактировании существующего кода, в котором уже используется один или другой набор типов, следует придерживаться выбранного типа.

Возможно, есть и другие случаи, но основное правило состоит в следующем: НИКОГДА НЕ используйте typedef, если вы не соблюдаете одно из этих правил.

В общем, указатель или структура, содержащие элементы, к которым можно получить прямой доступ, никогда не должны быть typedef.

Глава 6: Функции

Функции должны быть короткими и приятными, и выполнять только одно действие. Они должны помещаться на одном или двух экранах текста (размер экрана ISO/ANSI 80x24, как мы все знаем) и выполнять одно действие, но делать это хорошо.

Максимальная длина функции обратно пропорциональна сложности функции и уровню отступов. Итак, если у вас есть концептуально простая функция, которая представляет собой лишь один длинный (но простой) оператор вариант case, где вам нужно делать много мелочей для множества разных случаев, длинная функция — это нормально.

Однако, если у вас есть сложная функция, и вы подозреваете, что не слишком одаренный старшеклассник может даже не понять, о чем эта функция, следует придерживаться ограничений. Используйте вспомогательные функции с описательными именами (можно попросить компилятор встроить их, если считаете, что это критически важно для производительности, и он, вероятно, справится лучше).

Другим критерием функции является количество локальных переменных. Их не должно быть больше 5-10, или вы делаете что-то неправильно. Продумайте функцию заново и разбейте ее на более мелкие части. Человеческий мозг обычно легко отслеживает около 7 разных вещей, а больше — и он уже запутается. Вы знаете, что сейчас вы гений, но, возможно, через пару недель вам захочется понять, что именно вы делали.

В прототипах функций включайте имена параметров с типами данных. Хотя для языка C это и не требуется, но рекомендуется для Tarantool, потому что это простой способ добавить ценную информацию для читателя.

Обратите внимание, что тип возвращаемого значения функции располагается перед именем и сигнатурой функции.

Глава 7: Централизованный выход из функции

Хотя некоторые объявили аналог оператора goto устаревшим, его часто используют компиляторы в виде инструкции безусловной передачи управления.

Оператор goto пригодится, когда функция производит выход из нескольких мест и необходимо выполнить какие-то общие действия, такие как очистка. Если очистка не нужна, пусть функция возвращается напрямую.

Выбирайте имена меток, которые объясняют, что делает goto или почему. Пример хорошего имени: out_free_buffer:, если goto освобождает буфер. Избегайте таких имен из GW-BASIC, как err1: и err2:, поскольку вам придется перенумеровать их, если вы будете добавлять или удалять пути выхода, и в любом случае они затрудняют проверку.

Обоснование использования goto:

  • безусловные операторы легче понять и выполнять
  • уменьшается глубина вложения
  • предотвращаются ошибки по причине отсутствия обновления отдельных точек выхода при внесении изменений
  • уменьшает объем работы компилятора для оптимизации избыточного кода ;)
int
fun(int a)
{
  int result = 0;
  char *buffer;

  buffer = kmalloc(SIZE, GFP_KERNEL);
  if (!buffer)
    return -ENOMEM;

  if (condition1) {
    while (loop1) {
      ...
    }
    result = 1;
    goto out_free_buffer;
  }
  ...
out_free_buffer:
  kfree(buffer);
  return result;
}

Распространенный тип ошибок, о котором следует помнить, — однократное использование err, что выглядит так:

err:
  kfree(foo->bar);
  kfree(foo);
  return ret;

Ошибка в этом коде заключается в том, что на некоторых путях выхода foo принимает значение NULL. Обычно это можно исправить разделением ошибки на две метки err_free_bar: и err_free_foo::

err_free_bar:
 kfree(foo->bar);
err_free_foo:
 kfree(foo);
 return ret;

В идеале следует моделировать ошибки, чтобы проверить все пути выхода.

Глава 8: Комментирование

Комментарии полезны, но есть и опасность чрезмерного комментирования. НИКОГДА не пытайтесь объяснить в комментарии, КАК работает ваш код: гораздо лучше написать код так, чтобы принцип работы был очевиден, а объяснять плохо написанный код — это пустая трата времени.

Как правило, желательно, чтобы комментарии поясняли, ЧТО делает ваш код, а не КАК. Кроме того, постарайтесь не размещать комментарии внутри тела функции: если функция настолько сложна, что нужно отдельно комментировать ее части, скорее всего, вам надо вернуться к главе 6. Можно давать небольшие комментарии, чтобы отметить что-то особенно умное (или уродливое) или предупредить об этом, но старайтесь избегать лишнего. Вместо этого поставьте комментарии во главе функции, сообщите людям, что она делает, и, возможно, ПОЧЕМУ она это делает.

При комментировании функций Tarantool C API используйте систему комментирования Doxygen (разновидность Javadoc): то есть @tag, а не \\tag. Основные используемые теги: @param, @retval, @return, @see, @note и @todo.

Каждая функция, за исключением, пожалуй, очень короткой и очевидной, должна быть прокомментирована. Пример комментария функции может выглядеть следующим образом:

/**
 * Запись всех данных в дескриптор.
 *
 * Эта функция аналогична 'write' во всём кроме того, что она обеспечивает
 * запись всех данных в файл, если не возникает ошибка,
 * которую нельзя игнорировать.
 *
 * @retval 0  Выполнено
 * @retval 1 Ошибка (не EINTR)
 */
static int
write_all(int fd, void *data, size_t len);

Также важно комментировать типы данных независимо от того, базовые это типы или производные. Для этого используйте только одно объявление данных в строке (без запятой для объявления массива данных). Это оставляет вам место для небольшого комментария к каждому пункту с объяснением его использования.

Доступные структуры и важные элементы структуры также должны быть прокомментированы.

В C комментарии внутри и снаружи функции должны отличаться тем, как они начинаются. Все остальное — неправильно. Ниже приведены правильные примеры. /** используется для комментирования документации, /* — для локальных незадокументированных комментариев. Однако разница уже неявная, поэтому правило простое: снаружи функции используйте /**, внутри — /*.

/**
 * Комментарий снаружи функции, вариант 1.
 */

/** Комментарий снаружи функции, вариант 2. */

int
function()
{
    /* Комментарий внутри функции, вариант 1. */

    /*
     * Комментарий внутри функции, вариант 2.
     */
}

Если объявление функции и ее реализация разделены, то комментарий к функции должен относиться к части объявления функции. Обычно в файле заголовка. Не дублируйте комментарий.

Комментарий и сигнатура функции должны быть согласованы. Перепроверьте, что имена параметров те же, что и в комментарии, и означают одно и то же. Особенно, если вы изменили один из них, — убедитесь, что вы изменили и другой.

Глава 9: Макросы, перечисления и уровни регистровых передач (RTL)

Имена макросов, определяющих постоянные и метки в перечислениях, пишутся заглавными буквами.

#define CONSTANT 0x12345

Рекомендуется использовать перечисления при определении нескольких связанных постоянных.

Ценятся имена макросов, написанные ЗАГЛАВНЫМИ буквами, но похожие на функции макросы можно называть, используя буквы в нижнем регистре.

Как правило, рекомендуется использовать встроенные функции для макросов, похожих на функции.

Макросы с несколькими операторами должны быть заключены в блок do - while:

#define macrofun(a, b, c)       \
  do {                          \
    if (a == 5)                 \
      do_this(b, c);            \
  } while (0)

Во время использования макросов постарайтесь избегать следующего:

  1. Макросы, которые влияют на поток управления:

    #define FOO(x)                  \
  do {                          \
    if (blah(x) < 0)            \
      return -EBUGGERED;        \
  } while (0)

    это очень плохая идея. Он выглядит как вызов функции, но выходит из вызывающей функции; не ломайте внутреннего анализатора у того, кто будет читать код.

  2. Макросы, которые зависят от наличия локальной переменной с магическим именем:

    #define FOO(val) bar(index, val)

    могут показаться хорошей идеей, но они сбивают с толку, когда читаешь код, и такой код склонен ломаться от, казалось бы, невинных изменений.

  3. Макросы с аргументами, которые используются как l-значения: FOO(x) = y;. Это вам аукнется, если кто-то, например, сделает FOO встроенной функцией.

  4. Потеря приоритета: макросы, определяющие постоянные с использованием выражений, должны заключать выражение в круглые скобки. Остерегайтесь аналогичных проблем с макросами с использованием параметров.

    #define CONSTANT 0x4000
#define CONSTEXP (CONSTANT | 3)

  5. Конфликты в пространствах имен при определении локальных переменных в макросах, напоминающих функции:

    #define FOO(x)            \
({                        \
  typeof(x) ret;          \
  ret = calc_ret(x);      \
  (ret);                  \
})

    ret — обычное имя для локальной переменной; имя __foo_ret вряд ли вызовет конфликт с уже существующей переменной.

Глава 10: Выделение памяти

Лучше использовать специализированные генераторы, такие как region, mempool, smalloc, вместо malloc()/free()``для любых операций выделения памяти большого объема. Многократное использование ``malloc()/free() может привести к фрагментации памяти, чего следует избегать.

Всегда освобождайте всю выделенную память, даже выделенную при запуске. Мы стремимся к тому, чтобы valgrind не находил утечек памяти, и в большинстве случаев так же легко освободить выделенную память по free(), как и записать подавление valgrind. Освобождение всей выделенной памяти также помогает динамическому балансированию нагрузки: предполагается, что подключаемый модуль может динамически загружаться и выгружаться несколько раз, перезагрузка не должна приводить к утечке памяти.

Глава 11: Болезнь встраивания (inline)

Похоже, что распространено ошибочное представление о том, что в gcc есть волшебная опция ускорения, называемая встраиванием inline. Хотя использование встроенных строк может быть оправдано, довольно часто это не так. Избыток ключевого слова inline приводит к увеличению ядра, что в свою очередь, замедляет работу системы в целом из-за большего объема отпечатка icache для процессора и просто потому, что для pagecache доступно меньше памяти. Просто подумайте: непопадание в pagecache вызывает поиск по диску, который легко занимает 5 миллисекунд. Есть МНОГО циклов процессора, которые могут пройти в эти 5 миллисекунд.

Общее правило состоит в том, чтобы не вводить встраивание в функции, содержащие больше трех строк кода. Исключением из этого правила являются случаи, когда параметр известен как постоянная времени компиляции, и в результате вы знаете, что компилятор сможет оптимизировать большую часть ваших функций во время компиляции.

Часто утверждают, что беспроигрышным вариантом будет встраивание статических функций, используемых только один раз, поскольку нет компромиссов пространства. Хотя это технически правильно, gcc способен автоматически встраивать их, а проблема удаления встроенного, если появляется второй пользователь, перевешивает потенциальную ценность подсказки для gcc делать что-то, что он сделал бы в любом случае.

Глава 12: Возвращаемые значения и имена функций

Функции могут возвращать значения множества различных типов, и одним из наиболее распространенных является значение, которое указывает, была функция выполнена или нет.

В 99.99999% случаев в Tarantool при выполнении функции возвращается 0, в случае ошибки — ненулевое значение (обычно -1). Ошибки сохраняются в рабочей области диагностики (одна на файбер). Результатом функции никогда не будет код ошибки.

Функции, возвращаемое значение которых является фактическим результатом вычисления, а не указанием того, удалось ли выполнить вычисление, не подпадают под это правило. Обычно они указывают на сбой, возвращая некое недопустимое значение. Типичными примерами будут функции, возвращающие указатели; чтобы сообщить об ошибке, они используют NULL.

Глава 13: Редакторские строки режима (modelines) и прочий хлам

Некоторые редакторы могут интерпретировать встроенную в исходные файлы информацию о конфигурации, указанную специальными маркерами. Например, emacs интерпретирует строки, помеченные следующим образом:

-*- mode: c -*-

Или так:

/*
Local Variables:
compile-command: "gcc -DMAGIC_DEBUG_FLAG foo.c"
End:
*/

Vim интерпретирует маркеры, которые выглядят так:

/* vim:set sw=8 noet */

Не включайте их в исходные файлы. У людей есть свои собственные настройки редакторов, и ваши исходные файлы не должны их переопределять. Это относится к маркерам для отступов и конфигурации режима. У других людей могут быть свои собственные режимы или другие волшебные методы для правильной работы отступов.

Глава 14: Условная компиляция

По возможности не используйте препроцессорные директивы (#if, #ifdef) в файлах .c. Это затрудняет чтение кода и понимание логики. Вместо этого используйте такие директивы в файле заголовка, чтобы определить функции, используемые в этих файлах .c с заглушками в виде холостых команд в случае #else, а затем вызывайте эти функции безусловно из файлов .c. Компилятор не будет генерировать код для вызовов заглушек, при этом результат останется таким же, но логику будет проще понять.

Лучше компилировать целые функции, а не части функций или части выражений. Вместо того, чтобы вставить #ifdef в выражение, выделите часть или все выражение в отдельную вспомогательную функцию и примените условие к этой функции.

Если у вас есть функция или переменная, которая может не использоваться в конкретной конфигурации, и компилятор предупредит о том, что она использоваться не будет, не компилируйте ее и используйте для этого #if.

В конце любого крупного блока #if или #ifdef (более нескольких строк) после #endif в той же строке поместите комментарий, отмечающий используемое условное выражение. Например:

#ifdef CONFIG_SOMETHING
...
#endif /* CONFIG_SOMETHING */

Глава 15: Файлы заголовка

В заголовках используйте #pragma once. Для защиты заголовков мы используем такую конструкцию:

#ifndef THE_HEADER_IS_INCLUDED
#define THE_HEADER_IS_INCLUDED

// ... код заголовка ...

#endif // THE_HEADER_IS_INCLUDED

Работает нормально, но имя защиты THE_HEADER_IS_INCLUDED обычно перестает действовать при перемещении или переименовании файла. Это особенно неудобно, если у нескольких файлов одинаковое имя в проекте, но разные пути. Например, у нас есть 3 файла error.h, а это значит, что для каждого из них нужно придумать новое имя защиты заголовка, и не забыть обновить их при перемещении или переименовании файлов.

По этой причине мы и используем #pragma once во всем новом коде, что сокращает файл заголовка до такого:

#pragma once

// ... код заголовка ...

Глава 16: Прочие положения

  • Мы не применяем оператор ! к значениям, отличным от boolean. То есть, чтобы проверить, не равно ли целое число 0, вы используете != 0. Чтобы проверить, что указатель не NULL, используете != NULL. То же самое для ==.
  • Допускаются расширения GNU C99. Можно смешивать операторы и объявления в выражениях.
  • Не слишком актуальный список всех расширений семейства языка C можно найти по ссылке: http://gcc.gnu.org/onlinedocs/gcc-4.3.5/gcc/C-Extensions.html

Приложение I: Источники

Руководство по написанию кода на Python

Введение

Данный документ описывает соглашение о том, как писать код для языка Python, включая стандартную библиотеку, входящую в состав Python. Посмотрите также на сопутствующую PEP (Python enhanced proposal – заявку на улучшение языка Python), описывающую, какого стиля следует придерживаться при написании кода на C в реализации языка Python [1].

Данный документ, а также PEP 257 (Документирование кода) созданы на основе оригинала рекомендаций Гуидо ван Россума с добавлениями от Барри [2].

A Foolish Consistency is the Hobgoblin of Little Minds («Безрассудная согласованность сбивает с толку мелкие умы»)

Одна из ключевых идей Гвидо заключается в том, что код читается намного чаще, чем пишется. И рекомендации по стилю программирования предназначены улучшить читаемость кода и сделать его согласованным во множестве проектов на языке Python. Как написано в PEP 20, «Читаемость имеет значение».

В руководстве речь идет о согласованности. Согласованность с руководством очень важна. Согласованность внутри проекта еще важнее. А согласованность в пределах модуля или функции – самое важное.

Но очень важно понимать, когда можно отойти от рекомендаций, потому что руководство неприменимо. Если вы сомневаетесь, используйте свой опыт. Просто посмотрите на другие примеры и решите, какой выглядит лучше. И не бойтесь спросить!

Правила можно нарушить по одной из этих причин:

  1. Если применение правила сделает код менее читаемым даже для того, кто привык читать код, написанный по правилам.
  2. Чтобы не отступать по стилю от уже написанного не по правилам кода (возможно, в силу исторических причин) – впрочем, это может быть возможность причесать чужой код (в стиле XP).

Размещение кода

Отступы

Используйте 4 пробела на каждый уровень отступа.

Если вы не хотите наводить путаницу в очень старом коде, можете продолжать использовать отступы в 8 пробелов.

Продолжения строк должны выравнивать переносимые элементы либо вертикально, используя подразумевающееся объединение строк в скобках (круглых, квадратных или фигурных), либо с использованием висячего отступа. При использовании висячего отступа необходимо применять следующие соображения: на первой строке не должно быть аргументов, а остальные строки должны четко восприниматься как продолжение строки.

Правильно:

# выравнивание по открывающему разделителю
foo = long_function_name(var_one, var_two,
                         var_three, var_four)

# больше отступов, чтобы данный сегмент отличался от остальных.
def long_function_name(
        var_one, var_two, var_three,
        var_four):
    print(var_one)

Неправильно:

# запрещены аргументы на первой строке, если не используется вертикальное выравнивание
foo = long_function_name(var_one, var_two,
    var_three, var_four)

# необходимы дополнительные отступы для четких отличий
def long_function_name(
    var_one, var_two, var_three,
    var_four):
    print(var_one)

Возможно:

# Нет необходимости в дополнительных отступах.
foo = long_function_name(
  var_one, var_two,
  var_three, var_four)

Закрывающие круглые/квадратные/фигурные скобки в многострочных конструкциях могут находиться либо под первым символом последней строки списка (не пробелом), например:

my_list = [
    1, 2, 3,
    4, 5, 6,
    ]
result = some_function_that_takes_arguments(
    'a', 'b', 'c',
    'd', 'e', 'f',
    )

либо под первым символом строки, с которой начинается многострочная конструкция:

my_list = [
    1, 2, 3,
    4, 5, 6,
]
result = some_function_that_takes_arguments(
    'a', 'b', 'c',
    'd', 'e', 'f',
)

Табуляция или пробелы?

Никогда не смешивайте символы табуляции и пробелы.

Самый распространенный способ отступов в Python – пробелы. На втором месте – отступы только с использованием табуляции. Код, в котором используются и те, и другие типы отступов, следует исправить так, чтобы отступы в нем были расставлены только с помощью пробелов. При вызове интерпретатора в командной строке с параметром -t он выдаст предупреждение в случае использовании смешанного стиля в отступах. Запустив интерпретатор с параметром -tt, вы получите в этих местах ошибки. Рекомендуем использовать эти опции!

В новых проектах для отступов настоятельно рекомендуется использовать только пробелы. Во многих редакторах можно легко это делать.

Максимальная длина строки

Ограничьте максимальную длину строки 79 символами.

Пока еще есть немало устройств, где длина строки ограничена 80 символами; к тому же, ограничив ширину окна 80 символами, мы можем расположить несколько окон рядом друг с другом. Автоматический перенос строк на таких устройствах нарушит форматирование, и код будет труднее понять. Поэтому ограничьте длину строки 79 символами. Для длинных блоков текста (строки документации или комментарии) рекомендуется ограничиваться 72 символами.

Предпочтительный способ переноса длинных строк – использование подразумевающегося продолжения строки между обычными, квадратными и фигурными скобками. Длинные строки можно разбить на несколько строк в скобках. Это лучше, чем использовать обратную косую черту для продолжения строки.

Обратную косую черту можно использовать время от времени. Например, длинный оператор with не может работать с неявными продолжениями, так что обратная косая черта здесь подойдет:

with open('/path/to/some/file/you/want/to/read') as file_1, \
        open('/path/to/some/file/being/written', 'w') as file_2:
    file_2.write(file_1.read())

Еще один такой случай – операторы assert.

Делайте правильные отступы для перенесенной строки. Предпочтительнее вставить перенос строки после логического оператора, а не перед ним. Например:

class Rectangle(Blob):

    def __init__(self, width, height,
                 color='black', emphasis=None, highlight=0):
        if (width == 0 and height == 0 and
            color == 'red' and emphasis == 'strong' or
            highlight > 100):
            raise ValueError("sorry, you lose")
        if width == 0 and height == 0 and (color == 'red' or
                                           emphasis is None):
            raise ValueError("I don't think so -- values are %s, %s" %
                             (width, height))
        Blob.__init__(self, width, height,
                      color, emphasis, highlight)

Пустые строки

Отделяйте функции верхнего уровня и определения классов двумя пустыми строками.

Определения методов в пределах класса отделяйте одной пустой строкой.

Также можно добавлять пустые строки (не слишком часто) для выделения групп связанных функций. Пустые строки не стоит добавлять между несколькими связанными программами в одну строку (например, в формальной реализации).

Не слишком часто можно добавлять пустые строки в коде функций, чтобы отделить друг от друга логические части.

Python расценивает символ control+L (или ^L) как пробел. Многие редакторы обрабатывают его как разрыв страницы, поэтому его можно использовать для выделения логических части в файле на разных страницах. Обратите внимание, что не все редакторы распознают control+L и могут на его месте отображать другой символ.

Кодировка (PEP 263)

В коде ядра Python всегда должна использоваться кодировка ASCII или Latin-1 (также известную как ISO-8859-1). Начиная с версии Python 3.0, предпочтительной является кодировка UTF-8, а не Latin-1 (см. PEP 3120).

Для файлов с ASCII не следует объявлять кодировку. Используйте Latin-1 (или UTF-8), только если необходимо указать в комментарии или строке документации имя автора, содержащее в себе символ из Latin-1. В остальных случаях рекомендуется использовать управляющие символы x, u или U, чтобы вставить в строку символы не из ASCII.

Начиная с версии Python 3.0 и выше, в стандартной библиотеке действует следующая политика (см. PEP 3131): все идентификаторы в стандартной библиотеке Python ДОЛЖНЫ содержать только ASCII-символы и означать английские слова везде, где это возможно (во многих случаях используются сокращения или неанглийские технические термины). Кроме того, строки и комментарии также должны содержать лишь ASCII-символы. Исключения составляют: (a) тестовые сценарии для тестирования функций программы в других кодировках, и (b) имена авторов. Авторы, в именах которых есть буквы не из латинского алфавита, должны транслитерировать свои имена в латиницу.

В проектах с открытым кодом для широкой аудитории также рекомендуется использовать это правило.

Импорт

  • Импорт разных модулей должен быть на разных строках, например:

    Yes: import os
     import sys

No:  import sys, os

    В то же время, можно писать вот так:

    from subprocess import Popen, PIPE

  • Импорт всегда нужно делать в начале файла сразу после комментариев к модулю и строк документации, перед объявлением глобальных переменных и постоянных.

    Группируйте импорты в следующем порядке:

    1. импорты стандартной библиотеки
    2. импорты сторонних библиотек
    3. импорты модулей текущего проекта

    Между группами импортов вставляйте пустую строку.

    Указывайте все необходимые спецификации __all__ после импортов.

  • Относительные импорты крайне не рекомендуются. Всегда указывайте абсолютный путь к модулю для всех видов импорта. Даже сейчас, когда PEP 328 реализован в версии Python 2.5, явно использовать относительные импорты не рекомендуется. Абсолютные импорты более независимы и, как правило, обладают лучшей читаемостью.

  • При импорте класса из модуля с классами, обычно можно писать так:

    from myclass import MyClass
from foo.bar.yourclass import YourClass

    Если такое написание вызывает конфликт локальных имен, пишите:

    import myclass
import foo.bar.yourclass

    И используйте «myclass.MyClass» и «foo.bar.yourclass.YourClass».

Пробелы в выражениях и операторах

Наболевшие вопросы

Избегайте использования пробелов в следующих ситуациях:

  • Перед круглыми, фигурными и квадратными скобками и после них:

    Yes: spam(ham[1], {eggs: 2})
No:  spam( ham[ 1 ], { eggs: 2 } )

  • Сразу перед запятой, точкой с запятой, двоеточием:

    Yes: if x == 4: print x, y; x, y = y, x
No:  if x == 4 : print x , y ; x , y = y , x

  • Сразу перед открывающей скобкой, после которой начинается список аргументов при вызове функции:

    Yes: spam(1)
No:  spam (1)

  • Сразу перед открывающей скобкой, после которой идет индекс или срез:

    Yes: dict['key'] = list[index]
No:  dict ['key'] = list [index]

  • Больше одного пробела вокруг оператора присваивания (или другого) для того, чтобы выровнять его с другим оператором:

    Правильно:

    x = 1
y = 2
long_variable = 3

    Неправильно:

    x             = 1
y             = 2
long_variable = 3

Прочие рекомендации

  • Всегда окружайте эти знаки двухместных операций пробелами по одному с каждой стороны: присваивание (=), комбинированное присваивание (+=, -= и т.д.), сравнения (==, <, >, !=, <>, <=, >=, in, not in, is, is not), логические операторы (and, or, not).

  • Если используются знаки операций с разными приоритетами, рассмотрите возможность добавить пробелы вокруг операций с самым низким приоритетом. Судите сами, однако, никогда не используйте больше одного пробела, и всегда используйте одинаковое количество пробелов по обе стороны от знака.

    Правильно:

    i = i + 1
submitted += 1
x = x*2 - 1
hypot2 = x*x + y*y
c = (a+b) * (a-b)

    Неправильно:

    i=i+1
submitted +=1
x = x * 2 - 1
hypot2 = x * x + y * y
c = (a + b) * (a - b)

  • Не используйте пробелы для отделения знака =, когда он употребляется для обозначения аргумента ключевого слова или значения параметра по умолчанию.

    Правильно:

    def complex(real, imag=0.0):
    return magic(r=real, i=imag)

    Неправильно:

    def complex(real, imag = 0.0):
    return magic(r = real, i = imag)

  • Не рекомендуется использовать составные операторы (несколько операторов в одной строке).

    Правильно:

    if foo == 'blah':
    do_blah_thing()
do_one()
do_two()
do_three()

    Скорее неправильно:

    if foo == 'blah': do_blah_thing()
do_one(); do_two(); do_three()

  • Иногда можно разместить тело цикла if/for/while в той же строке, но если операторов несколько, никогда так не делайте. И избегайте свертывания таких длинных строк!

    Скорее неправильно:

    if foo == 'blah': do_blah_thing()
for x in lst: total += x
while t < 10: t = delay()

    Точно неправильно:

    if foo == 'blah': do_blah_thing()
else: do_non_blah_thing()

try: something()
finally: cleanup()

do_one(); do_two(); do_three(long, argument,
                             list, like, this)

if foo == 'blah': one(); two(); three()

Комментарии

Комментарии, которые противоречат коду, хуже, чем отсутствие комментариев. Всегда считайте первоочередной задачей исправить комментарии, если меняется код!

Комментарии должны представлять собой законченные предложения. Если комментарием будет фраза или предложение, первое слово должно быть написано с заглавной буквы, если только это не идентификатор, который пишется со строчной буквы (никогда не меняйте регистр идентификаторов!).

Если комментарий короткий, точку в конце предложения можно опустить. Блок комментариев обычно состоит из одного или более абзацев, составленных из полных предложений, поэтому каждое предложение должно заканчиваться точкой.

После точки в конце предложения следует ставить два пробела.

Если вы пишете на английском языке, не забывайте о рекомендациях Странка и Уайта по стилю.

Разработчики на языке Python из неанглоязычных стран, пишите комментарии на английском, если только вы не уверены на 120%, что ваш код никогда не будут читать люди, не знающие вашего родного языка.

Блок комментариев

Блок комментариев обычно сопровождает фрагмент кода (или весь код), который за ним следует, и находится на том же уровне отступов, что и сам код. Каждая строка блока комментариев должна начинаться с символа # и одного пробела после него (если только в самом тексте комментария нет отступов).

Абзацы в пределах блока комментариев отделяются строкой, состоящей из одного символа #.

Комментарии в строке с кодом

Старайтесь реже использовать подобные комментарии.

Встроенный комментарий находится в той же строке, что и оператор. Такие комментарии должны отделяться от оператора хотя бы двумя пробелами. Они должны начинаться с символа # и одного пробела.

Комментарии в строке с кодом не нужны и в действительности отвлекают от чтения, если они объясняют очевидное. Не пишите так:

x = x + 1                 # Увеличение x

Иногда, впрочем, они полезны:

x = x + 1                 # Место для рамки окна

Строки документации

Соглашения о написании хорошей документации (docstrings) увековечены в PEP 257.

  • Пишите документацию для всех доступных модулей, функций, классов, методов. Строки документации необязательны для внутренних методов, но нужно добавить комментарий о том, что делает метод. Комментарий должен идти после строки def.

  • PEP 257 объясняет, как правильно и хорошо писать документацию. Следует отметить, что очень важно, чтобы закрывающие """ стояли на отдельной строке, а предпочтительно, чтобы перед ними была и пустая строка, например:

    """Return a foobang

Optional plotz says to frobnicate the bizbaz first.

"""

  • Для однострочной документации можно оставить закрывающие """ на той же строке.

Контроль версий

Если вам нужно использовать Subversion, CVS или RCS в ваших исходных кодах, делайте это следующим образом:

__version__ = "$Revision$"
# $Source$

Эти строки следует указывать после документации модуля перед любым другим кодом, отделяя их пустыми строками сверху и снизу.

Соглашения по именованию

Соглашения по именованию переменных в Python довольно запущены, поэтому полной согласованности невозможно будет добиться. Тем не менее, ниже мы приводим список рекомендованных стандартов именования. Новые модули и пакеты (включая сторонние) должны быть написаны в соответствии с этими стандартами, но если уже существующая библиотека написана в другом стиле, предпочтительно поддерживать согласованность.

Описание: Стили имен

Существует много различных стилей именования. Полезно распознавать, какой стиль именования используется независимо от того, для чего он используется.

Обычно различают следующие стили именования:

  • b (отдельная строчная буква)

  • B (отдельная заглавная буква)

  • lowercase (слово в нижнем регистре)

  • lower_case_with_underscores (слова из строчных букв с символами подчеркивания)

  • UPPERCASE (заглавные буквы)

  • UPPERCASE_WITH_UNDERSCORES (слова из заглавных букв с символами подчеркивания)

  • CapitalizedWords (слова с заглавными буквами, или CapWords, или CamelCase – называется так, потому что прописные буквы внутри слова напоминают горбы верблюда [3]). Иногда называется StudlyCaps.

    Примечание: когда вы используете аббревиатуры в стиле CapWords, пишите все буквы аббревиатуры заглавными. HTTPServerError выглядит лучше, чем HttpServerError.

  • mixedCase (отличается от CapitalizedWords тем, что первое слово начинается со строчной буквы!)

  • Capitalized_Words_With_Underscores (слова с заглавными буквами и символами подчеркивания – уродливо!)

Еще есть стиль, в котором к именам из одной логической группы добавляется короткий уникальный префикс. Этот стиль редко используется в Python, но упомянем его для полноты изложения. Например, функция os.stat() возвращает кортеж, имена в котором традиционно выглядят так: st_mode, st_size, st_mtime и так далее. (Так сделано, чтобы подчеркнуть соответствие этих полей структуре системных вызовов POSIX, что помогает знакомым с ней разработчикам).

В библиотеке X11 используется префикс Х для всех доступных функций. В Python этот стиль считается лишним, потому что перед полями и именами методов стоит имя объекта, а перед именами функций стоит имя модуля.

Кроме того, используются следующие специальные формы записи имен с добавлением символа подчеркивания в начало или конец имени (их можно использовать с любым типом регистра):

  • _single_leading_underscore: слабый индикатор «для внутреннего пользования». Например, from M import * не будет импортировать объекты, имена которых начинаются с символа подчеркивания.

  • single_trailing_underscore_: используется по соглашению во избежание конфликтов с ключевыми словами Python, например:

    Tkinter.Toplevel(master, class_='ClassName')

  • __double_leading_underscore: изменяет имя атрибута класса (в классе FooBar, __boo становится _FooBar__boo; см. ниже).

  • __double_leading_and_trailing_underscore__: «волшебные» объекты или атрибуты, которые находятся в live in в пространствах имен, управляемых пользователем. Например, __init__, __import__ или __file__. Не придумывайте такие имена, используйте их только так, как написано в документации.

Предписания: соглашения по именованию

Имена, которых следует избегать

Никогда не используйте символы „l“ (строчная латинская буква эль), „O“ (заглавная латинская буква о) или „I“ (заглавная латинская буква ай) в качестве однобуквенных имен переменных.

В некоторых шрифтах эти символы неотличимы от цифр один и ноль. Если нельзя обойтись без „l“, пишите вместо нее „L“.

Имена модулей и пакетов

Имена модулей должны быть короткими и состоять из строчных букв. Можно использовать и символы подчеркивания, если это улучшает читаемость. Имена пакетов Python также должны быть короткими и состоять из строчных букв, но здесь символы подчеркивания не приветствуются.

Так как имена модулей отображаются в именах файлов, а некоторые файловые системы являются нечувствительными к регистру символов и обрезают длинные имена, очень важно использовать достаточно короткие имена модулей – это не проблема в Unix, но может стать проблемой при переносе кода в старые версии Windows, Mac или DOS.

Если для модуля расширения, написанного на С или C++, есть сопутствующий Python-модуль, содержащий интерфейс более высокого уровня (например, более объектно-ориентированный), модуль С/С++ начинается с символа подчеркивания (например, _socket).

Имена классов

Все имена классов должны соответствовать CapWords почти без исключений. Классы для внутреннего использования могут также начинаться с символа подчеркивания.

Имена исключений

Так как исключения должны быть классами, к исключениям применяются правила именования классов. Однако вы можете добавить суффикс «Error» в конце имени (если исключение действительно является ошибкой).

Имена глобальных переменных

(Будем надеяться, что такие имена используются только в пределах одного модуля.) Применяются те же правила, что и для имен функций.

В модули, которые предназначены для использования с помощью from M import *, следует добавить механизм __all__, чтобы предотвратить экспорт глобальных переменных, или же использовать старое соглашение, добавляя перед именами таких глобальных переменных один символ подчеркивания (которым можно обозначить глобальные переменные, которые используются только внутри модуля).

Имена функций

Имена функций должны состоять из строчных букв, а слова разделяться символами подчеркивания, чтобы улучшить читаемость.

mixedCase допускается только в тех местах, где уже преобладает такой стиль (например, threading.py), для обратной совместимости.

Аргументы функций и методов

Всегда используйте self в качестве первого аргумента метода экземпляра.

Всегда используйте cls в качестве первого аргумента метода класса.

Если имя аргумента функции конфликтует с зарезервированным ключевым словом, обычно лучше добавить в конец имени символ подчеркивания, а не сокращать слово или искажать его. Таким образом, class_ лучше, чем clss. (Возможно, будет лучше избегать конфликта имен путем подбора синонима).

Имена методов и переменные экземпляров

Используйте тот же стиль, что и для имен функций: они должны состоять из строчных букв, а слова разделяться символами подчеркивания, чтобы улучшить читаемость.

Используйте только один символ подчеркивания в начале слова для внутренних методов и переменных экземпляров.

Чтобы избежать конфликта имен с подклассами, добавьте два символа подчеркивания в начале слова, чтобы включить механизм изменения имен в Python.

Python изменяет эти имена: если в классе Foo есть атрибут с именем __a, к нему нельзя обратиться через Foo.__a. (Настойчивый пользователь всё равно может получить доступ через Foo._Foo__a.) Вообще, двойное подчеркивание в начале имени должно использоваться только во избежание конфликта имен с атрибутами классов, предназначенных для разделения на подклассы.

Примечание: есть некоторые разногласия по поводу использования имен __names (см. ниже).

Постоянные

Постоянные обычно объявляются на уровне модуля и записываются только заглавными буквами, а слова разделяются символами подчеркивания. Например: MAX_OVERFLOW, TOTAL.

Проектирование наследования

Обязательно решите, каким должен быть метод класса или переменная экземпляра класса (в общем, атрибут) – доступными (public) или внутренними (non-public). Если вы сомневаетесь, делайте их внутренними. Потом будет проще открыть к ним доступ, чем наоборот.

Доступные атрибуты – это такие атрибуты, которые будут использовать потребители ваших классов, и вы должны быть уверены в обратной совместимости. Внутренние атрибуты, в свою очередь, не предназначены для использования третьими лицами, поэтому вы можете не гарантировать, что не измените или не удалите эти атрибуты.

Мы не используем термин «закрытый» (private), потому что на самом деле в Python таких атрибутов не бывает (без ненужных дополнительных усилий).

Другой тип атрибутов классов принадлежит так называемому API подклассов (в других языках они часто называются защищенными – «protected»). Некоторые классы предназначены для наследования другими классами, которые расширяют или изменяют поведение базового класса. Когда вы проектируете такой класс, решите и явным образом укажите, какие атрибуты являются доступными (public), какие относятся к API подклассов (subclass API), а какие используются только базовым классом.

С учетом вышесказанного, сформулируем рекомендации:

  • В начале имени доступных атрибутов не должно быть символов подчеркивания.

  • Если имя доступного атрибута конфликтует с ключевым словом языка, добавьте в конец имени один символ подчеркивания. Это более предпочтительно, чем сокращать слово или искажать его (однако, у этого правила есть исключение: „cls“ – это предпочтительное написание любой переменной или аргумента, который означает класс, а особенно первого аргумента метода класса).

    Примечание 1:

    См. рекомендации по именам аргументов выше для методов класса.

  • Назовите простые открытые атрибуты понятными именами и не пишите сложные методы доступа и изменения (accessor/mutator). Следует помнить, что в Python очень легко расширить поведение функции, если потребуется. В этом случае используйте свойства (properties), чтобы скрыть функциональную реализацию за синтаксисом доступа к атрибутам.

    Примечание 1:

    Свойства работают только в классах нового стиля (new-style classes).

    Примечание 2:

    Постарайтесь избавиться от побочных эффектов, связанных с функциональным поведением, хотя такие вещи, как кэширование, вполне допустимы.

    Примечание 3:

    Избегайте использовать вычислительно затратные операции, потому что из-за записи с помощью атрибутов создается впечатление, что доступ происходит (относительно) быстро.

  • Если ваш класс предназначен для разделения на подклассы, но некоторые атрибуты не должны наследоваться подклассами, подумайте о добавлении в имена двух символов подчеркивания в начале и ни одного в конце. Механизм изменения имен в Python сработает так, что имя класса добавится к имени такого атрибута. Это позволит избежать конфликта имен, если в подклассах случайно появятся атрибуты с такими же именами.

    Примечание 1:

    Обратите внимание, что только имена простых классов используются в измененном имени, поэтому если в подклассе будет то же имя класса и имя атрибута, то снова возникнет конфликт имен.

    Примечание 2:

    Механизм изменения имен может затруднить отладку или работу с __getattr__(). Тем не менее, алгоритм хорошо документирован и легко реализуется вручную.

    Примечание 3:

    Не всем нравится механизм изменения имен. Постарайтесь достичь компромисса между необходимостью избежать конфликта имен и возможностью доступа к этим атрибутам.

Использованная литература

[1]ван Россум Гвидо. PEP 7, Руководство по программированию на языке C
[2]Руководство Барри по GNU Mailman
[3]Страница Википедии о CamelCase

Lua style guide

Для вдохновения:

Programming style is art. There is some arbitrariness to the rules, but there are sound rationales for them. It is useful not only to provide sound advice on style but to understand the underlying rationale behind the style recommendations:

The Zen of Python is good. Understand it and use wisely:

Красивое лучше, чем уродливое.
Явное лучше, чем неявное.
Простое лучше, чем сложное.
Сложное лучше, чем запутанное.
Плоское лучше, чем вложенное.
Разреженное лучше, чем плотное.
Читаемость имеет значение.
Особые случаи не настолько особые, чтобы нарушать правила.
При этом практичность важнее безупречности.
Ошибки никогда не должны замалчиваться.
Если не замалчиваются явно.
Встретив двусмысленность, отбрось искушение угадать.
Должен существовать один – и, желательно, только один – очевидный способ сделать это.
Хотя он поначалу может быть и не очевиден.
Сейчас лучше, чем никогда.
Хотя никогда зачастую лучше, чем прямо сейчас.
Если реализацию сложно объяснить – идея плоха.
Если реализацию легко объяснить – идея, возможно, хороша.
Пространства имен – отличная штука! Сделаем побольше!

https://www.python.org/dev/peps/pep-0020/

Indentation and formatting

Avoid global variables

Avoid using global variables. In exceptional cases, start the name of such a variable with _G, add a prefix, or add a table instead of a prefix:

-- Very bad
function bad_global_example()
end

function good_local_example()
end
-- Good
_G.modulename_good_local_example = good_local_example

-- Better
_G.modulename = {}
_G.modulename.good_local_example = good_local_example

Always use a prefix to avoid name conflicts.

Именование

Идиомы и шаблоны

Всегда пользуйтесь круглыми скобками при вызове функций, за исключением множественных случаев (распространенные идиомы в Lua):

Avoid the following constructions:

Avoid implicit casting to boolean in if conditions like if x then or if not x then. Such expressions will likely result in troubles with box.NULL. Instead of those conditions, use if x ~= nil then and if x == nil then.

Модули

Don’t start modules with license/authors/descriptions, you can write it in LICENSE/AUTHORS/README files. To write modules, use one of the two patterns (don’t use modules()):

local M = {}

function M.foo()
    ...
end

function M.bar()
    ...
end

return M

или

local function foo()
    ...
end

local function bar()
    ...
end

return {
    foo = foo,
    bar = bar,
}

Комментирование

Don’t forget to comment your Lua code. You shouldn’t comment Lua syntax (assume that the reader already knows the Lua language). Instead, tell about functions/variable names/etc.

Start a sentence with a capital letter and end with a period.

Многострочные комментарии: используйте соответствующие скобки (--[[ ]]--) вместо простых (--[[ ]]).

Public function comments:

--- Copy any table (shallow and deep version).
-- * deepcopy: copies all levels
-- * shallowcopy: copies only first level
-- Supports __copy metamethod for copying custom tables with metatables.
-- @function gsplit
-- @table         inp  original table
-- @shallow[opt]  sep  flag for shallow copy
-- @returns            table (copy)

Тестирование

Use the tap module for writing efficient tests. Example of a test file:

#!/usr/bin/env tarantool

local test = require('tap').test('table')
test:plan(31)

do
    -- Check basic table.copy (deepcopy).
    local example_table = {
        { 1, 2, 3 },
        { "help, I'm very nested", { { { } } } }
    }

    local copy_table = table.copy(example_table)

    test:is_deeply(
            example_table,
            copy_table,
            "checking, that deepcopy behaves ok"
    )
    test:isnt(
            example_table,
            copy_table,
            "checking, that tables are different"
    )
    test:isnt(
            example_table[1],
            copy_table[1],
            "checking, that tables are different"
    )
    test:isnt(
            example_table[2],
            copy_table[2],
            "checking, that tables are different"
    )
    test:isnt(
            example_table[2][2],
            copy_table[2][2],
            "checking, that tables are different"
    )
    test:isnt(
            example_table[2][2][1],
            copy_table[2][2][1],
            "checking, that tables are different"
    )
end

<...>

os.exit(test:check() and 0 or 1)

When you test your code, the output will be something like this:

TAP version 13
1..31
ok - checking, that deepcopy behaves ok
ok - checking, that tables are different
ok - checking, that tables are different
ok - checking, that tables are different
ok - checking, that tables are different
ok - checking, that tables are different
...

Error handling

Принимайте разнообразные значения и выдавайте строго определенные.

With error handling, this means that you must provide an error object as the second multi-return value in case of error. The error object can be a string, a Lua table, cdata, or userdata. In the latter three cases, it must have a __tostring metamethod defined.

В случае ошибки нулевое значение nil должно быть первым возвращаемым значением. В таком случае ошибку трудно игнорировать.

При проверке возвращаемых значений функции проверяйте сначала первый аргумент. Если это nil, ищите ошибку во втором аргументе:

local data, err = foo()
if data == nil then
    return nil, err
end
return bar(data)

Unless the performance of your code is paramount, try to avoid using more than two return values.

In rare cases, you may want to return nil as a legal return value. In this case, it’s OK to check for error first and then for return:

local data, err = foo()
if err == nil then
    return data
end
return nil, err

luacheck

Для проверки стиля кода Tarantool использует luacheck. Он анализирует различные аспекты кода, например неиспользуемые переменные, и иногда проверяет больше аспектов, чем нужно. Поэтому есть соглашение игнорировать некоторые предупреждения, которые выдает luacheck:

"212/self",   -- Неиспользуемый аргумент <self>.
"411",        -- Переопределение локальной переменной.
"421",        -- Переопределение локальной переменной на вложенном уровне.
"431",        -- Переопределение значения, заданного ранее, в функции.
"432",        -- Перегрузка аргумента на вложенном уровне.