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 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.

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

Create the hello directory for your application and go to this directory:
```
$ mkdir hello
$ cd hello
```
Initialize a new Go module:
```
$ go mod init example/hello
```
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

Declare the main() function:
```
func main() {

}
```

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

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

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

Версия:

Go

Sample database configuration

Starting a sample database application

Developing a client application

Creating an application

Importing „go-tarantool“ packages

Connecting to the database

Manipulating data

Inserting data

Querying data

Updating data

Deleting data

Executing stored procedures

Closing the connection

Starting a client application

Community Go connectors