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<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/discard.sgml,v 1.6 2010/04/03 07:23:00 petere Exp $
PostgreSQL documentation
-->
<refentry id="SQL-DISCARD">
<refmeta>
<refentrytitle>DISCARD</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>DISCARD</refname>
<refpurpose>discard session state</refpurpose>
</refnamediv>
<indexterm zone="sql-discard">
<primary>DISCARD</primary>
</indexterm>
<refsynopsisdiv>
<synopsis>
DISCARD { ALL | PLANS | TEMPORARY | TEMP }
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>DISCARD</> releases internal resources associated with a
database session. These resources are normally released at the end
of the session.
</para>
<para>
<command>DISCARD TEMP</> drops all temporary tables created in the
current session. <command>DISCARD PLANS</> releases all internally
cached query plans. <command>DISCARD ALL</> resets a session to
its original state, discarding temporary resources and resetting
session-local configuration changes.
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><literal>TEMPORARY</literal> or <literal>TEMP</literal></term>
<listitem>
<para>
Drops all temporary tables created in the current session.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>PLANS</literal></term>
<listitem>
<para>
Releases all cached query plans.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>ALL</literal></term>
<listitem>
<para>
Releases all temporary resources associated with the current
session and resets the session to its initial state.
Currently, this has the same effect as executing the following sequence
of statements:
<programlisting>
SET SESSION AUTHORIZATION DEFAULT;
RESET ALL;
DEALLOCATE ALL;
CLOSE ALL;
UNLISTEN *;
SELECT pg_advisory_unlock_all();
DISCARD PLANS;
DISCARD TEMP;
</programlisting>
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para>
<command>DISCARD ALL</> cannot be executed inside a transaction block.
</para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
<command>DISCARD</command> is a <productname>PostgreSQL</productname> extension.
</para>
</refsect1>
</refentry>
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