{"kind": "locale", "major": "18", "item": {"slug": "collation-pg-c-utf8", "name": "pg_c_utf8", "name_zh": "", "category": "Bootstrap collations", "summary": "sorts by Unicode code point; Unicode and POSIX character semantics", "aliases": [], "content_hash": "ee9ce9cef4d69ebefb37b11082a3c1788ad6f9247e99f8405768a22cdb09cd78", "versions": {"17": {"facts": [{"label": "Collisdeterministic", "value": "t"}, {"label": "Collcollate", "value": "_null_"}, {"label": "Collctype", "value": "_null_"}, {"label": "Colllocale", "value": "C.UTF-8"}, {"label": "Collicurules", "value": "_null_"}, {"label": "Collversion", "value": "1"}, {"label": "Collname", "value": "pg_c_utf8"}, {"label": "Collprovider", "value": "b"}, {"label": "Collencoding", "value": "6"}], "tables": [], "aliases": [], "catalog": {"oid": "811", "descr": "sorts by Unicode code point; Unicode and POSIX character semantics", "collname": "pg_c_utf8", "collctype": "_null_", "collowner": "POSTGRES", "colllocale": "C.UTF-8", "collcollate": "_null_", "collversion": "1", "collencoding": "6", "collicurules": "_null_", "collprovider": "b", "collnamespace": "pg_catalog", "collisdeterministic": "t"}, "related": [{"url": "/wiki/locale/provider-builtin/?v=17", "label": "builtin provider"}], "release": {"ref": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "label": "17.11", "major": "17", "channel": "stable", "revision": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979", "source_sha256": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979", "catalog_fingerprint": "4bbe3ac77becd618478f66aec420a533e9017be356c5c1d51a4b17f0fd497c07"}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "label": "Matching PostgreSQL source archive", "sha256": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, {"url": "/docs/17/collation.html#COLLATION-MANAGING-STANDARD", "path": "collation.html", "label": "PostgreSQL 17 English manual", "sha256": "67aac7b4c281b861af98f8f644ba2c3381358ffed48a74134fc269d0ae968029"}], "sections": [], "signature": "", "attributes": {"collname": "pg_c_utf8", "collctype": "_null_", "colllocale": "C.UTF-8", "collcollate": "_null_", "collversion": "1", "collencoding": "6", "collicurules": "_null_", "collprovider": "b", "collisdeterministic": "t"}, "source_oid": "811", "description": ["sorts by Unicode code point; Unicode and POSIX character semantics"], "manual_html": "<div class=\"sect3\" id=\"COLLATION-MANAGING-STANDARD\">\n<div class=\"titlepage\">\n<div>\n<div>\n<h4 class=\"title\">23.2.2.1.\u00a0Standard Collations </h4>\n</div>\n</div>\n</div>\n<p>On all platforms, the following collations are supported:</p>\n<div class=\"variablelist\">\n<dl class=\"variablelist\">\n<dt><span class=\"term\"><code class=\"literal\">unicode</code></span></dt>\n<dd>\n<p>This SQL standard collation sorts using the Unicode Collation Algorithm with the Default Unicode Collation Element Table. It is available in all encodings. ICU support is required to use this collation, and behavior may change if Postgres is built with a different version of ICU. (This collation has the same behavior as the ICU root locale; see <a class=\"xref\" href=\"/docs/17/collation.html#COLLATION-MANAGING-PREDEFINED-ICU-UND-X-ICU\"><code class=\"literal\">und-x-icu</code> (for <span class=\"quote\">\u201c<span class=\"quote\">undefined</span>\u201d</span>)</a>.)</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">ucs_basic</code></span></dt>\n<dd>\n<p>This SQL standard collation sorts using the Unicode code point values rather than natural language order, and only the ASCII letters <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">A</code></span>\u201d</span> through <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">Z</code></span>\u201d</span> are treated as letters. The behavior is efficient and stable across all versions. Only available for encoding <code class=\"literal\">UTF8</code>. (This collation has the same behavior as the libc locale specification <code class=\"literal\">C</code> in <code class=\"literal\">UTF8</code> encoding.)</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">pg_c_utf8</code></span></dt>\n<dd>\n<p>This collation sorts by Unicode code point values rather than natural language order. For the functions <code class=\"function\">lower</code>, <code class=\"function\">initcap</code>, and <code class=\"function\">upper</code>, it uses Unicode simple case mapping. For pattern matching (including regular expressions), it uses the POSIX Compatible variant of Unicode <a class=\"ulink\" href=\"https://www.unicode.org/reports/tr18/#Compatibility_Properties\">Compatibility Properties</a>. Behavior is efficient and stable within a <span class=\"productname\">Postgres</span> major version. This collation is only available for encoding <code class=\"literal\">UTF8</code>.</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">C</code> (equivalent to <code class=\"literal\">POSIX</code>)</span></dt>\n<dd>\n<p>The <code class=\"literal\">C</code> and <code class=\"literal\">POSIX</code> collations are based on <span class=\"quote\">\u201c<span class=\"quote\">traditional C</span>\u201d</span> behavior. They sort by byte values rather than natural language order, and only the ASCII letters <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">A</code></span>\u201d</span> through <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">Z</code></span>\u201d</span> are treated as letters. The behavior is efficient and stable across all versions for a given database encoding, but behavior may vary between different database encodings.</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">default</code></span></dt>\n<dd>\n<p>The <code class=\"literal\">default</code> collation selects the locale specified at database creation time.</p>\n</dd>\n</dl>\n</div>\n<p>Additional collations may be available depending on operating system support. The efficiency and stability of these additional collations depend on the collation provider, the provider version, and the locale.</p>\n</div>", "manual_path": "/docs/17/collation.html#COLLATION-MANAGING-STANDARD", "comparison_data": {"locale": "C.UTF-8", "collname": "pg_c_utf8", "collversion": "1", "collencoding": "6", "collprovider": "b", "collisdeterministic": "t"}, "comparison_hash": "9153f324be6b35decf20e2644732eb05bfe93f68adf8c02af9034bc155103011"}, "18": {"facts": [{"label": "Collisdeterministic", "value": "t"}, {"label": "Collcollate", "value": "_null_"}, {"label": "Collctype", "value": "_null_"}, {"label": "Colllocale", "value": "C.UTF-8"}, {"label": "Collicurules", "value": "_null_"}, {"label": "Collversion", "value": "1"}, {"label": "Collname", "value": "pg_c_utf8"}, {"label": "Collprovider", "value": "b"}, {"label": "Collencoding", "value": "6"}], "tables": [], "aliases": [], "catalog": {"oid": "811", "descr": "sorts by Unicode code point; Unicode and POSIX character semantics", "collname": "pg_c_utf8", "collctype": "_null_", "collowner": "POSTGRES", "colllocale": "C.UTF-8", "collcollate": "_null_", "collversion": "1", "collencoding": "6", "collicurules": "_null_", "collprovider": "b", "collnamespace": "pg_catalog", "collisdeterministic": "t"}, "related": [{"url": "/wiki/locale/provider-builtin/?v=18", "label": "builtin provider"}], "release": {"ref": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "label": "18.6", "major": "18", "channel": "stable", "revision": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f", "source_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f", "catalog_fingerprint": "65c93d6048ef30e61023a84f9680fa6a92b1c383b7eb226741170077eb078502"}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "label": "Matching PostgreSQL source archive", "sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "/docs/18/collation.html#COLLATION-MANAGING-STANDARD", "path": "collation.html", "label": "PostgreSQL 18 English manual", "sha256": "c98cbca2b2235a896f7fe438a88a99b8d6b9d1f50bdb49fe2794e9982a50797f"}], "sections": [], "signature": "", "attributes": {"collname": "pg_c_utf8", "collctype": "_null_", "colllocale": "C.UTF-8", "collcollate": "_null_", "collversion": "1", "collencoding": "6", "collicurules": "_null_", "collprovider": "b", "collisdeterministic": "t"}, "source_oid": "811", "description": ["sorts by Unicode code point; Unicode and POSIX character semantics"], "manual_html": "<div class=\"sect3\" id=\"COLLATION-MANAGING-STANDARD\">\n<div class=\"titlepage\">\n<div>\n<div>\n<h4 class=\"title\">23.2.2.1.\u00a0Standard Collations </h4>\n</div>\n</div>\n</div>\n<p>On all platforms, the following collations are supported:</p>\n<div class=\"variablelist\">\n<dl class=\"variablelist\">\n<dt><span class=\"term\"><code class=\"literal\">unicode</code></span></dt>\n<dd>\n<p>This SQL standard collation sorts using the Unicode Collation Algorithm with the Default Unicode Collation Element Table. It is available in all encodings. ICU support is required to use this collation, and behavior may change if <span class=\"productname\">PostgreSQL</span> is built with a different version of ICU. (This collation has the same behavior as the ICU root locale; see <a class=\"xref\" href=\"/docs/18/collation.html#COLLATION-MANAGING-PREDEFINED-ICU-UND-X-ICU\"><code class=\"literal\">und-x-icu</code> (for <span class=\"quote\">\u201c<span class=\"quote\">undefined</span>\u201d</span>)</a>.)</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">ucs_basic</code></span></dt>\n<dd>\n<p>This SQL standard collation sorts using the Unicode code point values rather than natural language order, and only the ASCII letters <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">A</code></span>\u201d</span> through <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">Z</code></span>\u201d</span> are treated as letters. The behavior is efficient and stable across all versions. Only available for encoding <code class=\"literal\">UTF8</code>. (This collation has the same behavior as the libc locale specification <code class=\"literal\">C</code> in <code class=\"literal\">UTF8</code> encoding.)</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">pg_unicode_fast</code></span></dt>\n<dd>\n<p>This collation sorts by Unicode code point values rather than natural language order. For the functions <code class=\"function\">lower</code>, <code class=\"function\">initcap</code>, and <code class=\"function\">upper</code> it uses Unicode full case mapping. For pattern matching (including regular expressions), it uses the Standard variant of Unicode <a class=\"ulink\" href=\"https://www.unicode.org/reports/tr18/#Compatibility_Properties\">Compatibility Properties</a>. Behavior is efficient and stable within a <span class=\"productname\">Postgres</span> major version. It is only available for encoding <code class=\"literal\">UTF8</code>.</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">pg_c_utf8</code></span></dt>\n<dd>\n<p>This collation sorts by Unicode code point values rather than natural language order. For the functions <code class=\"function\">lower</code>, <code class=\"function\">initcap</code>, and <code class=\"function\">upper</code>, it uses Unicode simple case mapping. For pattern matching (including regular expressions), it uses the POSIX Compatible variant of Unicode <a class=\"ulink\" href=\"https://www.unicode.org/reports/tr18/#Compatibility_Properties\">Compatibility Properties</a>. Behavior is efficient and stable within a <span class=\"productname\">PostgreSQL</span> major version. This collation is only available for encoding <code class=\"literal\">UTF8</code>.</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">C</code> (equivalent to <code class=\"literal\">POSIX</code>)</span></dt>\n<dd>\n<p>The <code class=\"literal\">C</code> and <code class=\"literal\">POSIX</code> collations are based on <span class=\"quote\">\u201c<span class=\"quote\">traditional C</span>\u201d</span> behavior. They sort by byte values rather than natural language order, and only the ASCII letters <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">A</code></span>\u201d</span> through <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">Z</code></span>\u201d</span> are treated as letters. The behavior is efficient and stable across all versions for a given database encoding, but behavior may vary between different database encodings.</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">default</code></span></dt>\n<dd>\n<p>The <code class=\"literal\">default</code> collation selects the locale specified at database creation time.</p>\n</dd>\n</dl>\n</div>\n<p>Additional collations may be available depending on operating system support. The efficiency and stability of these additional collations depend on the collation provider, the provider version, and the locale.</p>\n</div>", "manual_path": "/docs/18/collation.html#COLLATION-MANAGING-STANDARD", "comparison_data": {"locale": "C.UTF-8", "collname": "pg_c_utf8", "collversion": "1", "collencoding": "6", "collprovider": "b", "collisdeterministic": "t"}, "comparison_hash": "9153f324be6b35decf20e2644732eb05bfe93f68adf8c02af9034bc155103011"}, "19": {"facts": [{"label": "Collisdeterministic", "value": "t"}, {"label": "Collcollate", "value": "_null_"}, {"label": "Collctype", "value": "_null_"}, {"label": "Colllocale", "value": "C.UTF-8"}, {"label": "Collicurules", "value": "_null_"}, {"label": "Collversion", "value": "1"}, {"label": "Collname", "value": "pg_c_utf8"}, {"label": "Collprovider", "value": "b"}, {"label": "Collencoding", "value": "6"}], "tables": [], "aliases": [], "catalog": {"oid": "811", "descr": "sorts by Unicode code point; Unicode and POSIX character semantics", "collname": "pg_c_utf8", "collctype": "_null_", "collowner": "POSTGRES", "colllocale": "C.UTF-8", "collcollate": "_null_", "collversion": "1", "collencoding": "6", "collicurules": "_null_", "collprovider": "b", "collnamespace": "pg_catalog", "collisdeterministic": "t"}, "related": [{"url": "/wiki/locale/provider-builtin/?v=19", "label": "builtin provider"}], "release": {"ref": "https://ftp.postgresql.org/pub/source/v19beta4/postgresql-19beta4.tar.bz2", "label": "19beta4", "major": "19", "channel": "preview", "revision": "83157ee9c599d03b2f7a3d73ef3a56ec24e0e79cc2b3501a64d1364f56398c86", "source_sha256": "83157ee9c599d03b2f7a3d73ef3a56ec24e0e79cc2b3501a64d1364f56398c86", "catalog_fingerprint": "62fbf1a3689dbe8bf7e6b3372cfe6fbf867581427b3858a94c8419b77a4d2d1d"}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v19beta4/postgresql-19beta4.tar.bz2", "label": "Matching PostgreSQL source archive", "sha256": "83157ee9c599d03b2f7a3d73ef3a56ec24e0e79cc2b3501a64d1364f56398c86"}, {"url": "/docs/19/collation.html#COLLATION-MANAGING-STANDARD", "path": "collation.html", "label": "PostgreSQL 19 English manual", "sha256": "2eef5fdde9bbc23617bb28de2a76a46c48b5a51662dc9212b1ceb56a85199a5e"}], "sections": [], "signature": "", "attributes": {"collname": "pg_c_utf8", "collctype": "_null_", "colllocale": "C.UTF-8", "collcollate": "_null_", "collversion": "1", "collencoding": "6", "collicurules": "_null_", "collprovider": "b", "collisdeterministic": "t"}, "source_oid": "811", "description": ["sorts by Unicode code point; Unicode and POSIX character semantics"], "manual_html": "<div class=\"sect3\" id=\"COLLATION-MANAGING-STANDARD\">\n<div class=\"titlepage\">\n<div>\n<div>\n<h4 class=\"title\">23.2.2.1.\u00a0Standard Collations </h4>\n</div>\n</div>\n</div>\n<p>On all platforms, the following collations are supported:</p>\n<div class=\"variablelist\">\n<dl class=\"variablelist\">\n<dt><span class=\"term\"><code class=\"literal\">unicode</code></span></dt>\n<dd>\n<p>This SQL standard collation sorts using the Unicode Collation Algorithm with the Default Unicode Collation Element Table. It is available in all encodings. ICU support is required to use this collation, and behavior may change if <span class=\"productname\">PostgreSQL</span> is built with a different version of ICU. (This collation has the same behavior as the ICU root locale; see <a class=\"xref\" href=\"/docs/19/collation.html#COLLATION-MANAGING-PREDEFINED-ICU-UND-X-ICU\"><code class=\"literal\">und-x-icu</code> (for <span class=\"quote\">\u201c<span class=\"quote\">undefined</span>\u201d</span>)</a>.)</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">ucs_basic</code></span></dt>\n<dd>\n<p>This SQL standard collation sorts using the Unicode code point values rather than natural language order, and only the ASCII letters <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">A</code></span>\u201d</span> through <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">Z</code></span>\u201d</span> are treated as letters. The behavior is efficient and stable across all versions. Only available for encoding <code class=\"literal\">UTF8</code>. (This collation has the same behavior as the libc locale specification <code class=\"literal\">C</code> in <code class=\"literal\">UTF8</code> encoding.)</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">pg_unicode_fast</code></span></dt>\n<dd>\n<p>This collation sorts by Unicode code point values rather than natural language order. For the functions <code class=\"function\">lower</code>, <code class=\"function\">initcap</code>, and <code class=\"function\">upper</code> it uses Unicode full case mapping. For pattern matching (including regular expressions), it uses the Standard variant of Unicode <a class=\"ulink\" href=\"https://www.unicode.org/reports/tr18/#Compatibility_Properties\">Compatibility Properties</a>. Behavior is efficient and stable within a <span class=\"productname\">Postgres</span> major version. It is only available for encoding <code class=\"literal\">UTF8</code>.</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">pg_c_utf8</code></span></dt>\n<dd>\n<p>This collation sorts by Unicode code point values rather than natural language order. For the functions <code class=\"function\">lower</code>, <code class=\"function\">initcap</code>, and <code class=\"function\">upper</code>, it uses Unicode simple case mapping. For pattern matching (including regular expressions), it uses the POSIX Compatible variant of Unicode <a class=\"ulink\" href=\"https://www.unicode.org/reports/tr18/#Compatibility_Properties\">Compatibility Properties</a>. Behavior is efficient and stable within a <span class=\"productname\">PostgreSQL</span> major version. This collation is only available for encoding <code class=\"literal\">UTF8</code>.</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">C</code> (equivalent to <code class=\"literal\">POSIX</code>)</span></dt>\n<dd>\n<p>The <code class=\"literal\">C</code> and <code class=\"literal\">POSIX</code> collations are based on <span class=\"quote\">\u201c<span class=\"quote\">traditional C</span>\u201d</span> behavior. They sort by byte values rather than natural language order, and only the ASCII letters <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">A</code></span>\u201d</span> through <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">Z</code></span>\u201d</span> are treated as letters. The behavior is efficient and stable across all versions for a given database encoding, but behavior may vary between different database encodings.</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">default</code></span></dt>\n<dd>\n<p>The <code class=\"literal\">default</code> collation selects the locale specified at database creation time.</p>\n</dd>\n</dl>\n</div>\n<p>Additional collations may be available depending on operating system support. The efficiency and stability of these additional collations depend on the collation provider, the provider version, and the locale.</p>\n</div>", "manual_path": "/docs/19/collation.html#COLLATION-MANAGING-STANDARD", "comparison_data": {"locale": "C.UTF-8", "collname": "pg_c_utf8", "collversion": "1", "collencoding": "6", "collprovider": "b", "collisdeterministic": "t"}, "comparison_hash": "9153f324be6b35decf20e2644732eb05bfe93f68adf8c02af9034bc155103011"}, "20": {"facts": [{"label": "Collisdeterministic", "value": "t"}, {"label": "Collcollate", "value": "_null_"}, {"label": "Collctype", "value": "_null_"}, {"label": "Colllocale", "value": "C.UTF-8"}, {"label": "Collicurules", "value": "_null_"}, {"label": "Collversion", "value": "1"}, {"label": "Collname", "value": "pg_c_utf8"}, {"label": "Collprovider", "value": "b"}, {"label": "Collencoding", "value": "6"}], "tables": [], "aliases": [], "catalog": {"oid": "811", "descr": "sorts by Unicode code point; Unicode and POSIX character semantics", "collname": "pg_c_utf8", "collctype": "_null_", "collowner": "POSTGRES", "colllocale": "C.UTF-8", "collcollate": "_null_", "collversion": "1", "collencoding": "6", "collicurules": "_null_", "collprovider": "b", "collnamespace": "pg_catalog", "collisdeterministic": "t"}, "related": [{"url": "/wiki/locale/provider-builtin/?v=20", "label": "builtin provider"}], "release": {"ref": "https://ftp.postgresql.org/pub/snapshot/dev/postgresql-snapshot.tar.bz2", "label": "20devel", "major": "20", "channel": "devel", "revision": "4d3346909b201ac1648232cf290462a7070c119326f56196f1f0253ed80fae41", "source_sha256": "4d3346909b201ac1648232cf290462a7070c119326f56196f1f0253ed80fae41", "catalog_fingerprint": "398fbb9f262264053c02fbf79f88be0a6770c1473faa6ecd5931d6ec41b8258b", "source_snapshot_utc": "26-Sep-2026 20:22"}, "sources": [{"url": "https://ftp.postgresql.org/pub/snapshot/dev/postgresql-snapshot.tar.bz2", "label": "Matching PostgreSQL source archive", "sha256": "4d3346909b201ac1648232cf290462a7070c119326f56196f1f0253ed80fae41"}, {"url": "/docs/devel/collation.html#COLLATION-MANAGING-STANDARD", "path": "collation.html", "label": "PostgreSQL 20 English manual", "sha256": "3a5f2e6c1df8548d2a7d1f654dfc8fe598c1ce90f62169c3a2d11d8c736f940e"}], "sections": [], "signature": "", "attributes": {"collname": "pg_c_utf8", "collctype": "_null_", "colllocale": "C.UTF-8", "collcollate": "_null_", "collversion": "1", "collencoding": "6", "collicurules": "_null_", "collprovider": "b", "collisdeterministic": "t"}, "source_oid": "811", "description": ["sorts by Unicode code point; Unicode and POSIX character semantics"], "manual_html": "<div class=\"sect3\" id=\"COLLATION-MANAGING-STANDARD\">\n<div class=\"titlepage\">\n<div>\n<div>\n<h4 class=\"title\">23.2.2.1.\u00a0Standard Collations </h4>\n</div>\n</div>\n</div>\n<p>On all platforms, the following collations are supported:</p>\n<div class=\"variablelist\">\n<dl class=\"variablelist\">\n<dt><span class=\"term\"><code class=\"literal\">unicode</code></span></dt>\n<dd>\n<p>This SQL standard collation sorts using the Unicode Collation Algorithm with the Default Unicode Collation Element Table. It is available in all encodings. ICU support is required to use this collation, and behavior may change if <span class=\"productname\">PostgreSQL</span> is built with a different version of ICU. (This collation has the same behavior as the ICU root locale; see <a class=\"xref\" href=\"/docs/devel/collation.html#COLLATION-MANAGING-PREDEFINED-ICU-UND-X-ICU\"><code class=\"literal\">und-x-icu</code> (for <span class=\"quote\">\u201c<span class=\"quote\">undefined</span>\u201d</span>)</a>.)</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">ucs_basic</code></span></dt>\n<dd>\n<p>This SQL standard collation sorts using the Unicode code point values rather than natural language order, and only the ASCII letters <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">A</code></span>\u201d</span> through <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">Z</code></span>\u201d</span> are treated as letters. The behavior is efficient and stable across all versions. Only available for encoding <code class=\"literal\">UTF8</code>. (This collation has the same behavior as the libc locale specification <code class=\"literal\">C</code> in <code class=\"literal\">UTF8</code> encoding.)</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">pg_unicode_fast</code></span></dt>\n<dd>\n<p>This collation sorts by Unicode code point values rather than natural language order. For the functions <code class=\"function\">lower</code>, <code class=\"function\">initcap</code>, and <code class=\"function\">upper</code> it uses Unicode full case mapping. For pattern matching (including regular expressions), it uses the Standard variant of Unicode <a class=\"ulink\" href=\"https://www.unicode.org/reports/tr18/#Compatibility_Properties\">Compatibility Properties</a>. Behavior is efficient and stable within a <span class=\"productname\">Postgres</span> major version. It is only available for encoding <code class=\"literal\">UTF8</code>.</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">pg_c_utf8</code></span></dt>\n<dd>\n<p>This collation sorts by Unicode code point values rather than natural language order. For the functions <code class=\"function\">lower</code>, <code class=\"function\">initcap</code>, and <code class=\"function\">upper</code>, it uses Unicode simple case mapping. For pattern matching (including regular expressions), it uses the POSIX Compatible variant of Unicode <a class=\"ulink\" href=\"https://www.unicode.org/reports/tr18/#Compatibility_Properties\">Compatibility Properties</a>. Behavior is efficient and stable within a <span class=\"productname\">PostgreSQL</span> major version. This collation is only available for encoding <code class=\"literal\">UTF8</code>.</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">C</code> (equivalent to <code class=\"literal\">POSIX</code>)</span></dt>\n<dd>\n<p>The <code class=\"literal\">C</code> and <code class=\"literal\">POSIX</code> collations are based on <span class=\"quote\">\u201c<span class=\"quote\">traditional C</span>\u201d</span> behavior. They sort by byte values rather than natural language order, and only the ASCII letters <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">A</code></span>\u201d</span> through <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">Z</code></span>\u201d</span> are treated as letters. The behavior is efficient and stable across all versions for a given database encoding, but behavior may vary between different database encodings.</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">default</code></span></dt>\n<dd>\n<p>The <code class=\"literal\">default</code> collation selects the locale specified at database creation time.</p>\n</dd>\n</dl>\n</div>\n<p>Additional collations may be available depending on operating system support. The efficiency and stability of these additional collations depend on the collation provider, the provider version, and the locale.</p>\n</div>", "manual_path": "/docs/devel/collation.html#COLLATION-MANAGING-STANDARD", "comparison_data": {"locale": "C.UTF-8", "collname": "pg_c_utf8", "collversion": "1", "collencoding": "6", "collprovider": "b", "collisdeterministic": "t"}, "comparison_hash": "9153f324be6b35decf20e2644732eb05bfe93f68adf8c02af9034bc155103011"}}}, "snapshot": {"facts": [{"label": "Collisdeterministic", "value": "t"}, {"label": "Collcollate", "value": "_null_"}, {"label": "Collctype", "value": "_null_"}, {"label": "Colllocale", "value": "C.UTF-8"}, {"label": "Collicurules", "value": "_null_"}, {"label": "Collversion", "value": "1"}, {"label": "Collname", "value": "pg_c_utf8"}, {"label": "Collprovider", "value": "b"}, {"label": "Collencoding", "value": "6"}], "tables": [], "aliases": [], "catalog": {"oid": "811", "descr": "sorts by Unicode code point; Unicode and POSIX character semantics", "collname": "pg_c_utf8", "collctype": "_null_", "collowner": "POSTGRES", "colllocale": "C.UTF-8", "collcollate": "_null_", "collversion": "1", "collencoding": "6", "collicurules": "_null_", "collprovider": "b", "collnamespace": "pg_catalog", "collisdeterministic": "t"}, "related": [{"url": "/wiki/locale/provider-builtin/?v=18", "label": "builtin provider"}], "release": {"ref": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "label": "18.6", "major": "18", "channel": "stable", "revision": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f", "source_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f", "catalog_fingerprint": "65c93d6048ef30e61023a84f9680fa6a92b1c383b7eb226741170077eb078502"}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "label": "Matching PostgreSQL source archive", "sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "/docs/18/collation.html#COLLATION-MANAGING-STANDARD", "path": "collation.html", "label": "PostgreSQL 18 English manual", "sha256": "c98cbca2b2235a896f7fe438a88a99b8d6b9d1f50bdb49fe2794e9982a50797f"}], "sections": [], "signature": "", "attributes": {"collname": "pg_c_utf8", "collctype": "_null_", "colllocale": "C.UTF-8", "collcollate": "_null_", "collversion": "1", "collencoding": "6", "collicurules": "_null_", "collprovider": "b", "collisdeterministic": "t"}, "source_oid": "811", "description": ["sorts by Unicode code point; Unicode and POSIX character semantics"], "manual_html": "<div class=\"sect3\" id=\"COLLATION-MANAGING-STANDARD\">\n<div class=\"titlepage\">\n<div>\n<div>\n<h4 class=\"title\">23.2.2.1.\u00a0Standard Collations </h4>\n</div>\n</div>\n</div>\n<p>On all platforms, the following collations are supported:</p>\n<div class=\"variablelist\">\n<dl class=\"variablelist\">\n<dt><span class=\"term\"><code class=\"literal\">unicode</code></span></dt>\n<dd>\n<p>This SQL standard collation sorts using the Unicode Collation Algorithm with the Default Unicode Collation Element Table. It is available in all encodings. ICU support is required to use this collation, and behavior may change if <span class=\"productname\">PostgreSQL</span> is built with a different version of ICU. (This collation has the same behavior as the ICU root locale; see <a class=\"xref\" href=\"/docs/18/collation.html#COLLATION-MANAGING-PREDEFINED-ICU-UND-X-ICU\"><code class=\"literal\">und-x-icu</code> (for <span class=\"quote\">\u201c<span class=\"quote\">undefined</span>\u201d</span>)</a>.)</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">ucs_basic</code></span></dt>\n<dd>\n<p>This SQL standard collation sorts using the Unicode code point values rather than natural language order, and only the ASCII letters <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">A</code></span>\u201d</span> through <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">Z</code></span>\u201d</span> are treated as letters. The behavior is efficient and stable across all versions. Only available for encoding <code class=\"literal\">UTF8</code>. (This collation has the same behavior as the libc locale specification <code class=\"literal\">C</code> in <code class=\"literal\">UTF8</code> encoding.)</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">pg_unicode_fast</code></span></dt>\n<dd>\n<p>This collation sorts by Unicode code point values rather than natural language order. For the functions <code class=\"function\">lower</code>, <code class=\"function\">initcap</code>, and <code class=\"function\">upper</code> it uses Unicode full case mapping. For pattern matching (including regular expressions), it uses the Standard variant of Unicode <a class=\"ulink\" href=\"https://www.unicode.org/reports/tr18/#Compatibility_Properties\">Compatibility Properties</a>. Behavior is efficient and stable within a <span class=\"productname\">Postgres</span> major version. It is only available for encoding <code class=\"literal\">UTF8</code>.</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">pg_c_utf8</code></span></dt>\n<dd>\n<p>This collation sorts by Unicode code point values rather than natural language order. For the functions <code class=\"function\">lower</code>, <code class=\"function\">initcap</code>, and <code class=\"function\">upper</code>, it uses Unicode simple case mapping. For pattern matching (including regular expressions), it uses the POSIX Compatible variant of Unicode <a class=\"ulink\" href=\"https://www.unicode.org/reports/tr18/#Compatibility_Properties\">Compatibility Properties</a>. Behavior is efficient and stable within a <span class=\"productname\">PostgreSQL</span> major version. This collation is only available for encoding <code class=\"literal\">UTF8</code>.</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">C</code> (equivalent to <code class=\"literal\">POSIX</code>)</span></dt>\n<dd>\n<p>The <code class=\"literal\">C</code> and <code class=\"literal\">POSIX</code> collations are based on <span class=\"quote\">\u201c<span class=\"quote\">traditional C</span>\u201d</span> behavior. They sort by byte values rather than natural language order, and only the ASCII letters <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">A</code></span>\u201d</span> through <span class=\"quote\">\u201c<span class=\"quote\"><code class=\"literal\">Z</code></span>\u201d</span> are treated as letters. The behavior is efficient and stable across all versions for a given database encoding, but behavior may vary between different database encodings.</p>\n</dd>\n<dt><span class=\"term\"><code class=\"literal\">default</code></span></dt>\n<dd>\n<p>The <code class=\"literal\">default</code> collation selects the locale specified at database creation time.</p>\n</dd>\n</dl>\n</div>\n<p>Additional collations may be available depending on operating system support. The efficiency and stability of these additional collations depend on the collation provider, the provider version, and the locale.</p>\n</div>", "manual_path": "/docs/18/collation.html#COLLATION-MANAGING-STANDARD", "comparison_data": {"locale": "C.UTF-8", "collname": "pg_c_utf8", "collversion": "1", "collencoding": "6", "collprovider": "b", "collisdeterministic": "t"}, "comparison_hash": "9153f324be6b35decf20e2644732eb05bfe93f68adf8c02af9034bc155103011"}, "comparison": {"left": "17", "right": "18", "status": "unchanged", "diff": ""}}