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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-16 19:46:48 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-16 19:46:48 +0000
commit311bcfc6b3acdd6fd152798c7f287ddf74fa2a98 (patch)
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postgresql-15-311bcfc6b3acdd6fd152798c7f287ddf74fa2a98.zip
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+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>CREATE COLLATION</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="sql-createcast.html" title="CREATE CAST" /><link rel="next" href="sql-createconversion.html" title="CREATE CONVERSION" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">CREATE COLLATION</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sql-createcast.html" title="CREATE CAST">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><th width="60%" align="center">SQL Commands</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="sql-createconversion.html" title="CREATE CONVERSION">Next</a></td></tr></table><hr /></div><div class="refentry" id="SQL-CREATECOLLATION"><div class="titlepage"></div><a id="id-1.9.3.59.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">CREATE COLLATION</span></h2><p>CREATE COLLATION — define a new collation</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">
+CREATE COLLATION [ IF NOT EXISTS ] <em class="replaceable"><code>name</code></em> (
+ [ LOCALE = <em class="replaceable"><code>locale</code></em>, ]
+ [ LC_COLLATE = <em class="replaceable"><code>lc_collate</code></em>, ]
+ [ LC_CTYPE = <em class="replaceable"><code>lc_ctype</code></em>, ]
+ [ PROVIDER = <em class="replaceable"><code>provider</code></em>, ]
+ [ DETERMINISTIC = <em class="replaceable"><code>boolean</code></em>, ]
+ [ VERSION = <em class="replaceable"><code>version</code></em> ]
+)
+CREATE COLLATION [ IF NOT EXISTS ] <em class="replaceable"><code>name</code></em> FROM <em class="replaceable"><code>existing_collation</code></em>
+</pre></div><div class="refsect1" id="SQL-CREATECOLLATION-DESCRIPTION"><h2>Description</h2><p>
+ <code class="command">CREATE COLLATION</code> defines a new collation using
+ the specified operating system locale settings,
+ or by copying an existing collation.
+ </p><p>
+ To be able to create a collation, you must
+ have <code class="literal">CREATE</code> privilege on the destination schema.
+ </p></div><div class="refsect1" id="id-1.9.3.59.6"><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">IF NOT EXISTS</code></span></dt><dd><p>
+ Do not throw an error if a collation with the same name already exists.
+ A notice is issued in this case. Note that there is no guarantee that
+ the existing collation is anything like the one that would have been created.
+ </p></dd><dt><span class="term"><em class="replaceable"><code>name</code></em></span></dt><dd><p>
+ The name of the collation. The collation name can be
+ schema-qualified. If it is not, the collation is defined in the
+ current schema. The collation name must be unique within that
+ schema. (The system catalogs can contain collations with the
+ same name for other encodings, but these are ignored if the
+ database encoding does not match.)
+ </p></dd><dt><span class="term"><em class="replaceable"><code>locale</code></em></span></dt><dd><p>
+ This is a shortcut for setting <code class="symbol">LC_COLLATE</code>
+ and <code class="symbol">LC_CTYPE</code> at once. If you specify this,
+ you cannot specify either of those parameters.
+ </p></dd><dt><span class="term"><em class="replaceable"><code>lc_collate</code></em></span></dt><dd><p>
+ Use the specified operating system locale for
+ the <code class="symbol">LC_COLLATE</code> locale category.
+ </p></dd><dt><span class="term"><em class="replaceable"><code>lc_ctype</code></em></span></dt><dd><p>
+ Use the specified operating system locale for
+ the <code class="symbol">LC_CTYPE</code> locale category.
+ </p></dd><dt><span class="term"><em class="replaceable"><code>provider</code></em></span></dt><dd><p>
+ Specifies the provider to use for locale services associated with this
+ collation. Possible values
+ are: <code class="literal">icu</code>,<a id="id-1.9.3.59.6.2.6.2.1.2" class="indexterm"></a>
+ <code class="literal">libc</code>.
+ <code class="literal">libc</code> is the default.
+ The available choices depend on the operating system and build options.
+ </p></dd><dt><span class="term"><code class="literal">DETERMINISTIC</code></span></dt><dd><p>
+ Specifies whether the collation should use deterministic comparisons.
+ The default is true. A deterministic comparison considers strings that
+ are not byte-wise equal to be unequal even if they are considered
+ logically equal by the comparison. PostgreSQL breaks ties using a
+ byte-wise comparison. Comparison that is not deterministic can make the
+ collation be, say, case- or accent-insensitive. For that, you need to
+ choose an appropriate <code class="literal">LC_COLLATE</code> setting
+ <span class="emphasis"><em>and</em></span> set the collation to not deterministic here.
+ </p><p>
+ Nondeterministic collations are only supported with the ICU provider.
+ </p></dd><dt><span class="term"><em class="replaceable"><code>version</code></em></span></dt><dd><p>
+ Specifies the version string to store with the collation. Normally,
+ this should be omitted, which will cause the version to be computed
+ from the actual version of the collation as provided by the operating
+ system. This option is intended to be used
+ by <code class="command">pg_upgrade</code> for copying the version from an
+ existing installation.
+ </p><p>
+ See also <a class="xref" href="sql-altercollation.html" title="ALTER COLLATION"><span class="refentrytitle">ALTER COLLATION</span></a> for how to handle
+ collation version mismatches.
+ </p></dd><dt><span class="term"><em class="replaceable"><code>existing_collation</code></em></span></dt><dd><p>
+ The name of an existing collation to copy. The new collation
+ will have the same properties as the existing one, but it
+ will be an independent object.
+ </p></dd></dl></div></div><div class="refsect1" id="SQL-CREATECOLLATION-NOTES"><h2>Notes</h2><p>
+ <code class="command">CREATE COLLATION</code> takes a <code class="literal">SHARE ROW
+ EXCLUSIVE</code> lock, which is self-conflicting, on the
+ <code class="structname">pg_collation</code> system catalog, so only one
+ <code class="command">CREATE COLLATION</code> command can run at a time.
+ </p><p>
+ Use <code class="command">DROP COLLATION</code> to remove user-defined collations.
+ </p><p>
+ See <a class="xref" href="collation.html#COLLATION-CREATE" title="24.2.2.3. Creating New Collation Objects">Section 24.2.2.3</a> for more information on how to create collations.
+ </p><p>
+ When using the <code class="literal">libc</code> collation provider, the locale must
+ be applicable to the current database encoding.
+ See <a class="xref" href="sql-createdatabase.html" title="CREATE DATABASE"><span class="refentrytitle">CREATE DATABASE</span></a> for the precise rules.
+ </p></div><div class="refsect1" id="SQL-CREATECOLLATION-EXAMPLES"><h2>Examples</h2><p>
+ To create a collation from the operating system locale
+ <code class="literal">fr_FR.utf8</code>
+ (assuming the current database encoding is <code class="literal">UTF8</code>):
+</p><pre class="programlisting">
+CREATE COLLATION french (locale = 'fr_FR.utf8');
+</pre><p>
+ </p><p>
+ To create a collation using the ICU provider using German phone book sort order:
+</p><pre class="programlisting">
+CREATE COLLATION german_phonebook (provider = icu, locale = 'de-u-co-phonebk');
+</pre><p>
+ </p><p>
+ To create a collation from an existing collation:
+</p><pre class="programlisting">
+CREATE COLLATION german FROM "de_DE";
+</pre><p>
+ This can be convenient to be able to use operating-system-independent
+ collation names in applications.
+ </p></div><div class="refsect1" id="SQL-CREATECOLLATION-COMPAT"><h2>Compatibility</h2><p>
+ There is a <code class="command">CREATE COLLATION</code> statement in the SQL
+ standard, but it is limited to copying an existing collation. The
+ syntax to create a new collation is
+ a <span class="productname">PostgreSQL</span> extension.
+ </p></div><div class="refsect1" id="SQL-CREATECOLLATION-SEEALSO"><h2>See Also</h2><span class="simplelist"><a class="xref" href="sql-altercollation.html" title="ALTER COLLATION"><span class="refentrytitle">ALTER COLLATION</span></a>, <a class="xref" href="sql-dropcollation.html" title="DROP COLLATION"><span class="refentrytitle">DROP COLLATION</span></a></span></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="sql-createcast.html" title="CREATE CAST">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="sql-createconversion.html" title="CREATE CONVERSION">Next</a></td></tr><tr><td width="40%" align="left" valign="top">CREATE CAST </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="40%" align="right" valign="top"> CREATE CONVERSION</td></tr></table></div></body></html> \ No newline at end of file
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