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<sect1 id="functions-uuid">
<title>UUID Functions</title>
<indexterm zone="functions-uuid">
<primary>UUID</primary>
<secondary>generating</secondary>
</indexterm>
<indexterm>
<primary>gen_random_uuid</primary>
</indexterm>
<indexterm>
<primary>uuidv4</primary>
</indexterm>
<indexterm>
<primary>uuidv7</primary>
</indexterm>
<indexterm>
<primary>uuid_extract_timestamp</primary>
</indexterm>
<indexterm>
<primary>uuid_extract_version</primary>
</indexterm>
<para>
<xref linkend="func_uuid_gen_table"/> shows the <productname>PostgreSQL</productname>
functions that can be used to generate UUIDs.
</para>
<table id="func_uuid_gen_table">
<title><acronym>UUID</acronym> Generation Functions</title>
<tgroup cols="1">
<thead>
<row>
<entry role="func_table_entry">
<para role="func_signature">
Function
</para>
<para>
Description
</para>
<para>
Example(s)
</para>
</entry>
</row>
</thead>
<tbody>
<row>
<entry role="func_table_entry">
<para role="func_signature">
<type>gen_random_uuid</type>
<returnvalue>uuid</returnvalue>
</para>
<para role="func_signature">
<type>uuidv4</type>
<returnvalue>uuid</returnvalue>
</para>
<para>
Generate a version 4 (random) UUID.
</para>
<para>
<literal>gen_random_uuid()</literal>
<returnvalue>5b30857f-0bfa-48b5-ac0b-5c64e28078d1</returnvalue>
</para>
<para>
<literal>uuidv4()</literal>
<returnvalue>b42410ee-132f-42ee-9e4f-09a6485c95b8</returnvalue>
</para>
</entry>
</row>
<row>
<entry role="func_table_entry">
<para role="func_signature">
<type>uuidv7</type>
( <optional> <parameter>shift</parameter> <type>interval</type> </optional> )
<returnvalue>uuid</returnvalue>
</para>
<para>
Generate a version 7 (time-ordered) UUID. The timestamp is computed using UNIX timestamp
with millisecond precision + sub-millisecond timestamp + random. The optional parameter
<parameter>shift</parameter> will shift the computed timestamp by the given <type>interval</type>.
</para>
<para>
<literal>uuidv7()</literal>
<returnvalue>019535d9-3df7-79fb-b466-fa907fa17f9e</returnvalue>
</para>
</entry>
</row>
</tbody>
</tgroup>
</table>
<note>
<para>
The <xref linkend="uuid-ossp"/> module provides additional functions that
implement other standard algorithms for generating UUIDs.
</para>
</note>
<para>
<xref linkend="func_uuid_extract_table"/> shows the <productname>PostgreSQL</productname>
functions that can be used to extract information from UUIDs.
</para>
<table id="func_uuid_extract_table">
<title><acronym>UUID</acronym> Extraction Functions</title>
<tgroup cols="1">
<thead>
<row>
<entry role="func_table_entry">
<para role="func_signature">
Function
</para>
<para>
Description
</para>
<para>
Example(s)
</para>
</entry>
</row>
</thead>
<tbody>
<row>
<entry role="func_table_entry">
<para role="func_signature">
<type>uuid_extract_timestamp</type>
( <type>uuid</type> )
<returnvalue>timestamp with time zone</returnvalue>
</para>
<para>
Extracts a <type>timestamp with time zone</type> from UUID
version 1 and 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.
</para>
<para>
<literal>uuid_extract_timestamp('019535d9-3df7-79fb-b466-&zwsp;fa907fa17f9e'::uuid)</literal>
<returnvalue>2025-02-23 21:46:24.503-05</returnvalue>
</para>
</entry>
</row>
<row>
<entry role="func_table_entry">
<para role="func_signature">
<type>uuid_extract_version</type>
( <type>uuid</type> )
<returnvalue>smallint</returnvalue>
</para>
<para>
Extracts the version from a UUID of the variant described by
<ulink url="https://datatracker.ietf.org/doc/html/rfc9562">RFC 9562</ulink>. For
other variants, this function returns null. For example, for a UUID
generated by <function>gen_random_uuid</function>, this function will
return 4.
</para>
<para>
<literal>uuid_extract_version('41db1265-8bc1-4ab3-992f-&zwsp;885799a4af1d'::uuid)</literal>
<returnvalue>4</returnvalue>
</para>
<para>
<literal>uuid_extract_version('019535d9-3df7-79fb-b466-&zwsp;fa907fa17f9e'::uuid)</literal>
<returnvalue>7</returnvalue>
</para>
</entry>
</row>
</tbody>
</tgroup>
</table>
<para>
<productname>PostgreSQL</productname> also provides the usual comparison
operators shown in <xref linkend="functions-comparison-op-table"/> for
UUIDs.
</para>
<para>
See <xref linkend="datatype-uuid"/> for details on the data type
<type>uuid</type> in <productname>PostgreSQL</productname>.
</para>
</sect1>
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