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. Tarantool generates UUIDs following the rules for RFC 4122 version 4 variant 1.

API Reference

Below is list of all uuid functions and members.

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'}}})

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([byte-order])¶

Parameters:	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
Return:	a UUID
Rtype:	16-byte string

uuid.str()¶

Return:	a UUID
Rtype:	36-byte binary string

uuid.fromstr(uuid-str)¶

Parameters:	uuid-str (string) – UUID in 36-byte hexadecimal string
Return:	converted UUID
Rtype:	cdata

uuid.frombin(uuid-bin[, byte-order])¶

Parameters:	uuid-bin (string) – UUID in 16-byte binary string 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.
Return:	converted UUID
Rtype:	cdata

uuid.is_uuid(value)¶

Since version 2.6.1.

Parameters:	value – a value to check
Return:	true if the specified value is a UUID, and false otherwise
Rtype:	bool

object uuid_object¶

uuid_object:bin([byte-order])¶

Parameters:	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.
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
...