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<!--
doc/src/sgml/ref/discard.sgml
PostgreSQL documentation
-->
<refentry id="sql-discard">
<indexterm zone="sql-discard">
<primary>DISCARD</primary>
</indexterm>
<refmeta>
<refentrytitle>DISCARD</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>DISCARD</refname>
<refpurpose>discard session state</refpurpose>
</refnamediv>
<refsynopsisdiv>
<synopsis>
DISCARD { ALL | PLANS | SEQUENCES | TEMPORARY | TEMP }
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>DISCARD</command> releases internal resources associated with a
database session. This command is useful for partially or fully
resetting the session's state. There are several subcommands to
release different types of resources; the <command>DISCARD ALL</command>
variant subsumes all the others, and also resets additional state.
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><literal>PLANS</literal></term>
<listitem>
<para>
Releases all cached query plans, forcing re-planning to occur
the next time the associated prepared statement is used.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>SEQUENCES</literal></term>
<listitem>
<para>
Discards all cached sequence-related state,
including <function>currval()</function>/<function>lastval()</function>
information and any preallocated sequence values that have not
yet been returned by <function>nextval()</function>.
(See <xref linkend="sql-createsequence"/> for a description of
preallocated sequence values.)
</para>
</listitem>
</varlistentry>
<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>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>
CLOSE ALL;
SET SESSION AUTHORIZATION DEFAULT;
RESET ALL;
DEALLOCATE ALL;
UNLISTEN *;
SELECT pg_advisory_unlock_all();
DISCARD PLANS;
DISCARD TEMP;
DISCARD SEQUENCES;
</programlisting></para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para>
<command>DISCARD ALL</command> 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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