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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 EXTENSION</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-createeventtrigger.html" title="CREATE EVENT TRIGGER" /><link rel="next" href="sql-createforeigndatawrapper.html" title="CREATE FOREIGN DATA WRAPPER" /></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">CREATE EXTENSION</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sql-createeventtrigger.html" title="CREATE EVENT TRIGGER">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-createforeigndatawrapper.html" title="CREATE FOREIGN DATA WRAPPER">Next</a></td></tr></table><hr></hr></div><div class="refentry" id="SQL-CREATEEXTENSION"><div class="titlepage"></div><a id="id-1.9.3.64.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">CREATE EXTENSION</span></h2><p>CREATE EXTENSION — install an extension</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">
CREATE EXTENSION [ IF NOT EXISTS ] <em class="replaceable"><code>extension_name</code></em>
[ WITH ] [ SCHEMA <em class="replaceable"><code>schema_name</code></em> ]
[ VERSION <em class="replaceable"><code>version</code></em> ]
[ FROM <em class="replaceable"><code>old_version</code></em> ]
[ CASCADE ]
</pre></div><div class="refsect1" id="id-1.9.3.64.5"><h2>Description</h2><p>
<code class="command">CREATE EXTENSION</code> loads a new extension into the current
database. There must not be an extension of the same name already loaded.
</p><p>
Loading an extension essentially amounts to running the extension's script
file. The script will typically create new <acronym class="acronym">SQL</acronym> objects such as
functions, data types, operators and index support methods.
<code class="command">CREATE EXTENSION</code> additionally records the identities
of all the created objects, so that they can be dropped again if
<code class="command">DROP EXTENSION</code> is issued.
</p><p>
Loading an extension requires the same privileges that would be
required to create its component objects. For most extensions this
means superuser or database owner privileges are needed.
The user who runs <code class="command">CREATE EXTENSION</code> becomes the
owner of the extension for purposes of later privilege checks, as well
as the owner of any objects created by the extension's script.
</p></div><div class="refsect1" id="id-1.9.3.64.6"><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 an extension with the same name already
exists. A notice is issued in this case. Note that there is no
guarantee that the existing extension is anything like the one that
would have been created from the currently-available script file.
</p></dd><dt><span class="term"><em class="replaceable"><code>extension_name</code></em></span></dt><dd><p>
The name of the extension to be
installed. <span class="productname">PostgreSQL</span> will create the
extension using details from the file
<code class="literal">SHAREDIR/extension/</code><em class="replaceable"><code>extension_name</code></em><code class="literal">.control</code>.
</p></dd><dt><span class="term"><em class="replaceable"><code>schema_name</code></em></span></dt><dd><p>
The name of the schema in which to install the extension's
objects, given that the extension allows its contents to be
relocated. The named schema must already exist.
If not specified, and the extension's control file does not specify a
schema either, the current default object creation schema is used.
</p><p>
If the extension specifies a <code class="literal">schema</code> parameter in its
control file, then that schema cannot be overridden with
a <code class="literal">SCHEMA</code> clause. Normally, an error will be raised if
a <code class="literal">SCHEMA</code> clause is given and it conflicts with the
extension's <code class="literal">schema</code> parameter. However, if
the <code class="literal">CASCADE</code> clause is also given,
then <em class="replaceable"><code>schema_name</code></em> is
ignored when it conflicts. The
given <em class="replaceable"><code>schema_name</code></em> will be
used for installation of any needed extensions that do not
specify <code class="literal">schema</code> in their control files.
</p><p>
Remember that the extension itself is not considered to be within any
schema: extensions have unqualified names that must be unique
database-wide. But objects belonging to the extension can be within
schemas.
</p></dd><dt><span class="term"><em class="replaceable"><code>version</code></em></span></dt><dd><p>
The version of the extension to install. This can be written as
either an identifier or a string literal. The default version is
whatever is specified in the extension's control file.
</p></dd><dt><span class="term"><em class="replaceable"><code>old_version</code></em></span></dt><dd><p>
<code class="literal">FROM</code> <em class="replaceable"><code>old_version</code></em>
must be specified when, and only when, you are attempting to install
an extension that replaces an <span class="quote">“<span class="quote">old style</span>”</span> module that is just
a collection of objects not packaged into an extension. This option
causes <code class="command">CREATE EXTENSION</code> to run an alternative installation
script that absorbs the existing objects into the extension, instead
of creating new objects. Be careful that <code class="literal">SCHEMA</code> specifies
the schema containing these pre-existing objects.
</p><p>
The value to use for <em class="replaceable"><code>old_version</code></em> is determined by the
extension's author, and might vary if there is more than one version
of the old-style module that can be upgraded into an extension.
For the standard additional modules supplied with pre-9.1
<span class="productname">PostgreSQL</span>, use <code class="literal">unpackaged</code>
for <em class="replaceable"><code>old_version</code></em> when
updating a module to extension style.
</p></dd><dt><span class="term"><code class="literal">CASCADE</code></span></dt><dd><p>
Automatically install any extensions that this extension depends on
that are not already installed. Their dependencies are likewise
automatically installed, recursively. The <code class="literal">SCHEMA</code> clause,
if given, applies to all extensions that get installed this way.
Other options of the statement are not applied to
automatically-installed extensions; in particular, their default
versions are always selected.
</p></dd></dl></div></div><div class="refsect1" id="id-1.9.3.64.7"><h2>Notes</h2><p>
Before you can use <code class="command">CREATE EXTENSION</code> to load an extension
into a database, the extension's supporting files must be installed.
Information about installing the extensions supplied with
<span class="productname">PostgreSQL</span> can be found in
<a class="link" href="contrib.html" title="Appendix F. Additional Supplied Modules">Additional Supplied Modules</a>.
</p><p>
The extensions currently available for loading can be identified from the
<a class="link" href="view-pg-available-extensions.html" title="52.65. pg_available_extensions"><code class="structname">pg_available_extensions</code></a>
or
<a class="link" href="view-pg-available-extension-versions.html" title="52.66. pg_available_extension_versions"><code class="structname">pg_available_extension_versions</code></a>
system views.
</p><p>
For information about writing new extensions, see
<a class="xref" href="extend-extensions.html" title="38.16. Packaging Related Objects into an Extension">Section 38.16</a>.
</p></div><div class="refsect1" id="id-1.9.3.64.8"><h2>Examples</h2><p>
Install the <a class="link" href="hstore.html" title="F.16. hstore">hstore</a> extension into the
current database:
</p><pre class="programlisting">
CREATE EXTENSION hstore;
</pre><p>
</p><p>
Update a pre-9.1 installation of <code class="literal">hstore</code> into
extension style:
</p><pre class="programlisting">
CREATE EXTENSION hstore SCHEMA public FROM unpackaged;
</pre><p>
Be careful to specify the schema in which you installed the existing
<code class="literal">hstore</code> objects.
</p></div><div class="refsect1" id="id-1.9.3.64.9"><h2>Compatibility</h2><p>
<code class="command">CREATE EXTENSION</code> is a <span class="productname">PostgreSQL</span>
extension.
</p></div><div class="refsect1" id="id-1.9.3.64.10"><h2>See Also</h2><span class="simplelist"><a class="xref" href="sql-alterextension.html" title="ALTER EXTENSION"><span class="refentrytitle">ALTER EXTENSION</span></a>, <a class="xref" href="sql-dropextension.html" title="DROP EXTENSION"><span class="refentrytitle">DROP EXTENSION</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-createeventtrigger.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-createforeigndatawrapper.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">CREATE EVENT TRIGGER </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> CREATE FOREIGN DATA WRAPPER</td></tr></table></div></body></html>
