<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >Shutting Down the Server</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="Server Run-time Environment" HREF="runtime.html"><LINK REL="PREVIOUS" TITLE="Managing Kernel Resources" HREF="kernel-resources.html"><LINK REL="NEXT" TITLE="Encryption Options" HREF="encryption-options.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="kernel-resources.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="runtime.html" >Fast Backward</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" >Chapter 16. Server Run-time Environment</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="runtime.html" >Fast Forward</A ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="encryption-options.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="POSTMASTER-SHUTDOWN" >16.6. Shutting Down the Server</A ></H1 ><A NAME="AEN19308" ></A ><P > There are several ways to shut down the database server. You control the type of shutdown by sending different signals to the <TT CLASS="COMMAND" >postmaster</TT > process. <P ></P ></P><DIV CLASS="VARIABLELIST" ><DL ><DT ><SPAN CLASS="SYSTEMITEM" >SIGTERM</SPAN ><A NAME="AEN19316" ></A ></DT ><DD ><P > After receiving <SPAN CLASS="SYSTEMITEM" >SIGTERM</SPAN >, the server disallows new connections, but lets existing sessions end their work normally. It shuts down only after all of the sessions terminate normally. This is the <I CLASS="FIRSTTERM" >Smart Shutdown</I >. </P ></DD ><DT ><SPAN CLASS="SYSTEMITEM" >SIGINT</SPAN ><A NAME="AEN19325" ></A ></DT ><DD ><P > The server disallows new connections and sends all existing server processes <SPAN CLASS="SYSTEMITEM" >SIGTERM</SPAN >, which will cause them to abort their current transactions and exit promptly. It then waits for the server processes to exit and finally shuts down. This is the <I CLASS="FIRSTTERM" >Fast Shutdown</I >. </P ></DD ><DT ><SPAN CLASS="SYSTEMITEM" >SIGQUIT</SPAN ><A NAME="AEN19334" ></A ></DT ><DD ><P > This is the <I CLASS="FIRSTTERM" >Immediate Shutdown</I >, which will cause the <TT CLASS="COMMAND" >postmaster</TT > process to send a <SPAN CLASS="SYSTEMITEM" >SIGQUIT</SPAN > to all child processes and exit immediately, without properly shutting itself down. The child processes likewise exit immediately upon receiving <SPAN CLASS="SYSTEMITEM" >SIGQUIT</SPAN >. This will lead to recovery (by replaying the WAL log) upon next start-up. This is recommended only in emergencies. </P ></DD ></DL ></DIV ><P> </P ><P > The <A HREF="app-pg-ctl.html" ><SPAN CLASS="APPLICATION" >pg_ctl</SPAN ></A > program provides a convenient interface for sending these signals to shut down the server. </P ><P > Alternatively, you can send the signal directly using <TT CLASS="COMMAND" >kill</TT >. The <ACRONYM CLASS="ACRONYM" >PID</ACRONYM > of the <TT CLASS="COMMAND" >postmaster</TT > process can be found using the <TT CLASS="COMMAND" >ps</TT > program, or from the file <TT CLASS="FILENAME" >postmaster.pid</TT > in the data directory. For example, to do a fast shutdown: </P><PRE CLASS="SCREEN" >$ <KBD CLASS="USERINPUT" >kill -INT `head -1 /usr/local/pgsql/data/postmaster.pid`</KBD ></PRE ><P> </P ><DIV CLASS="IMPORTANT" ><BLOCKQUOTE CLASS="IMPORTANT" ><P ><B >Important: </B > It is best not to use <SPAN CLASS="SYSTEMITEM" >SIGKILL</SPAN > to shut down the server. Doing so will prevent the server from releasing shared memory and semaphores, which may then have to be done manually before a new server can be started. Furthermore, <SPAN CLASS="SYSTEMITEM" >SIGKILL</SPAN > kills the <TT CLASS="COMMAND" >postmaster</TT > process without letting it relay the signal to its subprocesses, so it will be necessary to kill the individual subprocesses by hand as well. </P ></BLOCKQUOTE ></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="kernel-resources.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="encryption-options.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Managing Kernel Resources</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="runtime.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Encryption Options</TD ></TR ></TABLE ></DIV ></BODY ></HTML >