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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>ALTER 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-alteraggregate.html" title="ALTER AGGREGATE" /><link rel="next" href="sql-alterconversion.html" title="ALTER CONVERSION" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">ALTER COLLATION</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sql-alteraggregate.html" title="ALTER AGGREGATE">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 11.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="sql-alterconversion.html" title="ALTER CONVERSION">Next</a></td></tr></table><hr></hr></div><div class="refentry" id="SQL-ALTERCOLLATION"><div class="titlepage"></div><a id="id-1.9.3.5.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">ALTER COLLATION</span></h2><p>ALTER COLLATION — change the definition of a collation</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">
ALTER COLLATION <em class="replaceable"><code>name</code></em> REFRESH VERSION
ALTER COLLATION <em class="replaceable"><code>name</code></em> RENAME TO <em class="replaceable"><code>new_name</code></em>
ALTER COLLATION <em class="replaceable"><code>name</code></em> OWNER TO { <em class="replaceable"><code>new_owner</code></em> | CURRENT_USER | SESSION_USER }
ALTER COLLATION <em class="replaceable"><code>name</code></em> SET SCHEMA <em class="replaceable"><code>new_schema</code></em>
</pre></div><div class="refsect1" id="id-1.9.3.5.5"><h2>Description</h2><p>
<code class="command">ALTER COLLATION</code> changes the definition of a
collation.
</p><p>
You must own the collation to use <code class="command">ALTER COLLATION</code>.
To alter the owner, you must also be a direct or indirect member of the new
owning role, and that role must have <code class="literal">CREATE</code> privilege on
the collation's schema. (These restrictions enforce that altering the
owner doesn't do anything you couldn't do by dropping and recreating the
collation. However, a superuser can alter ownership of any collation
anyway.)
</p></div><div class="refsect1" id="id-1.9.3.5.6"><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>name</code></em></span></dt><dd><p>
The name (optionally schema-qualified) of an existing collation.
</p></dd><dt><span class="term"><em class="replaceable"><code>new_name</code></em></span></dt><dd><p>
The new name of the collation.
</p></dd><dt><span class="term"><em class="replaceable"><code>new_owner</code></em></span></dt><dd><p>
The new owner of the collation.
</p></dd><dt><span class="term"><em class="replaceable"><code>new_schema</code></em></span></dt><dd><p>
The new schema for the collation.
</p></dd><dt><span class="term"><code class="literal">REFRESH VERSION</code></span></dt><dd><p>
Update the collation's version.
See <a class="xref" href="sql-altercollation.html#SQL-ALTERCOLLATION-NOTES" title="Notes">Notes</a> below.
</p></dd></dl></div></div><div class="refsect1" id="SQL-ALTERCOLLATION-NOTES"><h2>Notes</h2><p>
When using collations provided by the ICU library, the ICU-specific version
of the collator is recorded in the system catalog when the collation object
is created. When the collation is used, the current version is
checked against the recorded version, and a warning is issued when there is
a mismatch, for example:
</p><pre class="screen">
WARNING: collation "xx-x-icu" has version mismatch
DETAIL: The collation in the database was created using version 1.2.3.4, but the operating system provides version 2.3.4.5.
HINT: Rebuild all objects affected by this collation and run ALTER COLLATION pg_catalog."xx-x-icu" REFRESH VERSION, or build PostgreSQL with the right library version.
</pre><p>
A change in collation definitions can lead to corrupt indexes and other
problems because the database system relies on stored objects having a
certain sort order. Generally, this should be avoided, but it can happen
in legitimate circumstances, such as when
using <code class="command">pg_upgrade</code> to upgrade to server binaries linked
with a newer version of ICU. When this happens, all objects depending on
the collation should be rebuilt, for example,
using <code class="command">REINDEX</code>. When that is done, the collation version
can be refreshed using the command <code class="literal">ALTER COLLATION ... REFRESH
VERSION</code>. This will update the system catalog to record the
current collator version and will make the warning go away. Note that this
does not actually check whether all affected objects have been rebuilt
correctly.
</p><p>
The following query can be used to identify all collations in the current
database that need to be refreshed and the objects that depend on them:
</p><pre class="programlisting">
SELECT pg_describe_object(refclassid, refobjid, refobjsubid) AS "Collation",
pg_describe_object(classid, objid, objsubid) AS "Object"
FROM pg_depend d JOIN pg_collation c
ON refclassid = 'pg_collation'::regclass AND refobjid = c.oid
WHERE c.collversion <> pg_collation_actual_version(c.oid)
ORDER BY 1, 2;
</pre><p>
</p></div><div class="refsect1" id="id-1.9.3.5.8"><h2>Examples</h2><p>
To rename the collation <code class="literal">de_DE</code> to
<code class="literal">german</code>:
</p><pre class="programlisting">
ALTER COLLATION "de_DE" RENAME TO german;
</pre><p>
</p><p>
To change the owner of the collation <code class="literal">en_US</code> to
<code class="literal">joe</code>:
</p><pre class="programlisting">
ALTER COLLATION "en_US" OWNER TO joe;
</pre></div><div class="refsect1" id="id-1.9.3.5.9"><h2>Compatibility</h2><p>
There is no <code class="command">ALTER COLLATION</code> statement in the SQL
standard.
</p></div><div class="refsect1" id="id-1.9.3.5.10"><h2>See Also</h2><span class="simplelist"><a class="xref" href="sql-createcollation.html" title="CREATE COLLATION"><span class="refentrytitle">CREATE 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-alteraggregate.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="sql-commands.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="sql-alterconversion.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">ALTER AGGREGATE </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> ALTER CONVERSION</td></tr></table></div></body></html>
