<!-- doc/src/sgml/contrib.sgml -->

<appendix id="contrib">
 <title>Additional Supplied Modules</title>

 <para>
  This appendix contains information regarding the modules that
  can be found in the <literal>contrib</literal> directory of the
  <productname>PostgreSQL</> distribution.
  These include porting tools, analysis utilities,
  and plug-in features that are not part of the core PostgreSQL system,
  mainly because they address a limited audience or are too experimental
  to be part of the main source tree.  This does not preclude their
  usefulness.
 </para>

 <para>
  When building from the source distribution, these modules are not built
  automatically, unless you build the "world" target
  (see <xref linkend="build">).
  You can build and install all of them by running:
<screen>
<userinput>gmake</userinput>
<userinput>gmake install</userinput>
</screen>
  in the <literal>contrib</literal> directory of a configured source tree;
  or to build and install
  just one selected module, do the same in that module's subdirectory.
  Many of the modules have regression tests, which can be executed by
  running:
<screen>
<userinput>gmake installcheck</userinput>
</screen>
  once you have a <productname>PostgreSQL</> server running.  (Note that
  <literal>gmake check</> is not supported; you must have an operational
  database server to perform these tests, and you must have built and
  installed the module(s) to be tested.)
 </para>

 <para>
  If you are using a pre-packaged version of <productname>PostgreSQL</>,
  these modules are typically made available as a separate subpackage,
  such as <literal>postgresql-contrib</>.
 </para>

 <para>
  Many modules supply new user-defined functions, operators, or types.
  To make use of one of these modules, after you have installed the code
  you need to register the new SQL objects in the database system.
  In <productname>PostgreSQL</> 9.1 and later, this is done by executing
  a <xref linkend="sql-createextension"> command.  In a fresh database,
  you can simply do

<programlisting>
CREATE EXTENSION <replaceable>module_name</>;
</programlisting>

  This command must be run by a database superuser.  This registers the
  new SQL objects in the current database only, so you need to run this
  command in each database that you want
  the module's facilities to be available in.  Alternatively, run it in
  database <literal>template1</> so that the extension will be copied into
  subsequently-created databases by default.
 </para>

 <para>
  Many modules allow you to install their objects in a schema of your
  choice.  To do that, add <literal>SCHEMA
  <replaceable>schema_name</></literal> to the <command>CREATE EXTENSION</>
  command.  By default, the objects will be placed in your current creation
  target schema, typically <literal>public</>.
 </para>

 <para>
  If your database was brought forward by dump and reload from a pre-9.1
  version of <productname>PostgreSQL</>, and you had been using the pre-9.1
  version of the module in it, you should instead do

<programlisting>
CREATE EXTENSION <replaceable>module_name</> FROM unpackaged;
</programlisting>

  This will update the pre-9.1 objects of the module into a proper
  <firstterm>extension</> object.  Future updates to the module will be
  managed by <xref linkend="sql-alterextension">.
  For more information about extension updates, see
  <xref linkend="extend-extensions">.
 </para>

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</appendix>
