Module uuid

Overview

A “UUID” is a Universally unique identifier. If an application requires that a value be unique only within a single computer or on a single database, then a simple counter is better than a UUID, because getting a UUID is time-consuming (it requires a syscall). For clusters of computers, or widely distributed applications, UUIDs are better.

Index

Below is list of all uuid functions and members.

uuid.nil

A nil object

uuid.new()

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'}})

Now you can insert uuids into the space:

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]
...

Return:	a UUID
Rtype:	cdata

uuid.__call()

Return:	a UUID
Rtype:	cdata

uuid.bin()

Return:	a UUID
Rtype:	16-byte string

uuid.str()

Return:	a UUID
Rtype:	36-byte binary string

uuid.fromstr(uuid_str)

Parameters:	uuid_str – UUID in 36-byte hexadecimal string
Return:	converted UUID
Rtype:	cdata

uuid.frombin(uuid_bin)

Parameters:	uuid_str – UUID in 16-byte binary string
Return:	converted UUID
Rtype:	cdata

object uuid_object

uuid_object:bin([byte-order])

byte-order can be one of next flags:

• ‘l’ - little-endian,
• ‘b’ - big-endian,
• ‘h’ - endianness depends on host (default),
• ‘n’ - endianness depends on network

Parameters:	byte-order (string) – one of 'l', 'b', 'h' or 'n'.
Return:	UUID converted from cdata input value.
Rtype:	16-byte binary string

uuid_object:str()

Return:	UUID converted from cdata input value.
Rtype:	36-byte hexadecimal string

uuid_object:isnil()

The all-zero UUID value can be expressed as uuid.NULL, or as uuid.fromstr('00000000-0000-0000-0000-000000000000'). The comparison with an all-zero value can also be expressed as uuid_with_type_cdata == uuid.NULL.

Return:	true if the value is all zero, otherwise false.
Rtype:	bool

Example

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
...