> For the complete documentation index, see [llms.txt](https://docs.postgresql.tw/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.postgresql.tw/the-sql-language/functions/functions-uuid.md).

# 9.14. UUID Functions \#

[Table 9.45](#FUNC_UUID_GEN_TABLE) shows the PostgreSQL functions that can be used to generate UUIDs.

**Table 9.45. UUID Generation Functions**

| <p>Function</p><p>Description</p><p>Example(s)</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| <p><code>gen\_random\_uuid</code> ( ) → <code>uuid</code></p><p><code>uuidv4</code> ( ) → <code>uuid</code></p><p>Generates a version 4 (random) UUID</p><p><code>gen\_random\_uuid()</code> → <code>5b30857f-0bfa-48b5-ac0b-5c64e28078d1</code></p><p><code>uuidv4()</code> → <code>b42410ee-132f-42ee-9e4f-09a6485c95b8</code></p>                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| <p><code>uuidv7</code> ( \[ <em><code>shift</code></em> <code>interval</code> ] ) → <code>uuid</code></p><p>Generates a version 7 (time-ordered) UUID. The timestamp is computed using UNIX timestamp with millisecond precision + sub-millisecond timestamp + random. The optional parameter <em><code>shift</code></em> will shift the computed timestamp by the given <code>interval</code>. Infinite interval values are not accepted. The shifted timestamp must fall within the range supported by UUID version 7's 48-bit millisecond timestamp field: from 1970-01-01 00:00:00 UTC to approximately year 10889. An error is raised if the resulting timestamp is outside this range.</p><p><code>uuidv7()</code> → <code>019535d9-3df7-79fb-b466-fa907fa17f9e</code></p> |

<br>

## Note

The [uuid-ossp](/appendixes/contrib/uuid-ossp.md) module provides additional functions that implement other standard algorithms for generating UUIDs.

[Table 9.46](#FUNC_UUID_EXTRACT_TABLE) shows the PostgreSQL functions that can be used to extract information from UUIDs.

**Table 9.46. UUID Extraction Functions**

| <p>Function</p><p>Description</p><p>Example(s)</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| <p><code>uuid\_extract\_timestamp</code> ( <code>uuid</code> ) → <code>timestamp with time zone</code></p><p>Extracts a <code>timestamp with time zone</code> from a UUID of version 1 or 7. For other versions, this function returns null. Note that the extracted timestamp is not necessarily exactly equal to the time the UUID was generated; this depends on the implementation that generated the UUID.</p><p><code>uuid\_extract\_timestamp('019535d9-3df7-79fb-b466-​fa907fa17f9e'::uuid)</code> → <code>2025-02-23 21:46:24.503-05</code></p>                                                          |
| <p><code>uuid\_extract\_version</code> ( <code>uuid</code> ) → <code>smallint</code></p><p>Extracts the version from a UUID of one of the variants described by <a href="https://datatracker.ietf.org/doc/html/rfc9562">RFC 9562</a>. For other variants, this function returns null. For example, for a UUID generated by <code>gen\_random\_uuid()</code>, this function will return 4.</p><p><code>uuid\_extract\_version('41db1265-8bc1-4ab3-992f-​885799a4af1d'::uuid)</code> → <code>4</code></p><p><code>uuid\_extract\_version('019535d9-3df7-79fb-b466-​fa907fa17f9e'::uuid)</code> → <code>7</code></p> |

<br>

PostgreSQL also provides the usual comparison operators shown in [Table 9.1](/the-sql-language/functions/functions-comparison.md#FUNCTIONS-COMPARISON-OP-TABLE) for UUIDs.

See [Section 8.12](/the-sql-language/datatype/datatype-uuid.md) for details on the data type `uuid` in PostgreSQL.

***

原文：[PostgreSQL 18.6 Documentation](https://www.postgresql.org/docs/18/functions-uuid.html)（英文原文，待翻譯）


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