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<!--
doc/src/sgml/ref/unlisten.sgml
PostgreSQL documentation
-->
<refentry id="sql-unlisten">
<indexterm zone="sql-unlisten">
<primary>UNLISTEN</primary>
</indexterm>
<refmeta>
<refentrytitle>UNLISTEN</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>UNLISTEN</refname>
<refpurpose>stop listening for a notification</refpurpose>
</refnamediv>
<refsynopsisdiv>
<synopsis>
UNLISTEN { <replaceable class="parameter">channel</replaceable> | * }
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>UNLISTEN</command> is used to remove an existing
registration for <command>NOTIFY</command> events.
<command>UNLISTEN</command> cancels any existing registration of
the current <productname>PostgreSQL</productname> session as a
listener on the notification channel named <replaceable
class="parameter">channel</replaceable>. The special wildcard
<literal>*</literal> cancels all listener registrations for the
current session.
</para>
<para>
<xref linkend="sql-notify"/>
contains a more extensive
discussion of the use of <command>LISTEN</command> and
<command>NOTIFY</command>.
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">channel</replaceable></term>
<listitem>
<para>
Name of a notification channel (any identifier).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>*</literal></term>
<listitem>
<para>
All current listen registrations for this session are cleared.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para>
You can unlisten something you were not listening for; no warning or error
will appear.
</para>
<para>
At the end of each session, <command>UNLISTEN *</command> is
automatically executed.
</para>
<para>
A transaction that has executed <command>UNLISTEN</command> cannot be
prepared for two-phase commit.
</para>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
To make a registration:
<programlisting>
LISTEN virtual;
NOTIFY virtual;
Asynchronous notification "virtual" received from server process with PID 8448.
</programlisting>
</para>
<para>
Once <command>UNLISTEN</command> has been executed, further <command>NOTIFY</command>
messages will be ignored:
<programlisting>
UNLISTEN virtual;
NOTIFY virtual;
-- no NOTIFY event is received
</programlisting></para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
There is no <command>UNLISTEN</command> command in the SQL standard.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-listen"/></member>
<member><xref linkend="sql-notify"/></member>
</simplelist>
</refsect1>
</refentry>
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