<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >pg_listener</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REV="MADE" HREF="mailto:pgsql-docs@postgresql.org"><LINK REL="HOME" TITLE="PostgreSQL 8.0.11 Documentation" HREF="index.html"><LINK REL="UP" TITLE="System Catalogs" HREF="catalogs.html"><LINK REL="PREVIOUS" TITLE="pg_largeobject" HREF="catalog-pg-largeobject.html"><LINK REL="NEXT" TITLE="pg_namespace" HREF="catalog-pg-namespace.html"><LINK REL="STYLESHEET" TYPE="text/css" HREF="stylesheet.css"><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"><META NAME="creation" CONTENT="2007-02-02T03:57:22"></HEAD ><BODY CLASS="SECT1" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="5" ALIGN="center" VALIGN="bottom" >PostgreSQL 8.0.11 Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="catalog-pg-largeobject.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="catalogs.html" >Fast Backward</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" >Chapter 41. System Catalogs</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="catalogs.html" >Fast Forward</A ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="catalog-pg-namespace.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="CATALOG-PG-LISTENER" >41.20. <TT CLASS="STRUCTNAME" >pg_listener</TT ></A ></H1 ><A NAME="AEN53787" ></A ><P > The catalog <TT CLASS="STRUCTNAME" >pg_listener</TT > supports the <A HREF="sql-listen.html" ><I >LISTEN</I ></A > and <A HREF="sql-notify.html" ><I >NOTIFY</I ></A > commands. A listener creates an entry in <TT CLASS="STRUCTNAME" >pg_listener</TT > for each notification name it is listening for. A notifier scans <TT CLASS="STRUCTNAME" >pg_listener</TT > and updates each matching entry to show that a notification has occurred. The notifier also sends a signal (using the PID recorded in the table) to awaken the listener from sleep. </P ><DIV CLASS="TABLE" ><A NAME="AEN53795" ></A ><P ><B >Table 41-20. <TT CLASS="STRUCTNAME" >pg_listener</TT > Columns</B ></P ><TABLE BORDER="1" CLASS="CALSTABLE" ><COL><COL><COL><COL><THEAD ><TR ><TH >Name</TH ><TH >Type</TH ><TH >References</TH ><TH >Description</TH ></TR ></THEAD ><TBODY ><TR ><TD ><TT CLASS="STRUCTFIELD" >relname</TT ></TD ><TD ><TT CLASS="TYPE" >name</TT ></TD ><TD > </TD ><TD >Notify condition name. (The name need not match any actual relation in the database; the name <TT CLASS="STRUCTFIELD" >relname</TT > is historical.) </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >listenerpid</TT ></TD ><TD ><TT CLASS="TYPE" >int4</TT ></TD ><TD > </TD ><TD >PID of the server process that created this entry.</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >notification</TT ></TD ><TD ><TT CLASS="TYPE" >int4</TT ></TD ><TD > </TD ><TD > Zero if no event is pending for this listener. If an event is pending, the PID of the server process that sent the notification. </TD ></TR ></TBODY ></TABLE ></DIV ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="catalog-pg-largeobject.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="catalog-pg-namespace.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><TT CLASS="STRUCTNAME" >pg_largeobject</TT ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="catalogs.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><TT CLASS="STRUCTNAME" >pg_namespace</TT ></TD ></TR ></TABLE ></DIV ></BODY ></HTML >