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postmaster.sgml

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    • Bruce Momjian's avatar
      a033daf5
      Commit to match discussed elog() changes. Only update is that LOG is · a033daf5
      Bruce Momjian authored
      now just below FATAL in server_min_messages.  Added more text to
      highlight ordering difference between it and client_min_messages.
      
      ---------------------------------------------------------------------------
      
      REALLYFATAL => PANIC
      STOP => PANIC
      New INFO level the prints to client by default
      New LOG level the prints to server log by default
      Cause VACUUM information to print only to the client
      NOTICE => INFO where purely information messages are sent
      DEBUG => LOG for purely server status messages
      DEBUG removed, kept as backward compatible
      DEBUG5, DEBUG4, DEBUG3, DEBUG2, DEBUG1 added
      DebugLvl removed in favor of new DEBUG[1-5] symbols
      New server_min_messages GUC parameter with values:
              DEBUG[5-1], INFO, NOTICE, ERROR, LOG, FATAL, PANIC
      New client_min_messages GUC parameter with values:
              DEBUG[5-1], LOG, INFO, NOTICE, ERROR, FATAL, PANIC
      Server startup now logged with LOG instead of DEBUG
      Remove debug_level GUC parameter
      elog() numbers now start at 10
      Add test to print error message if older elog() values are passed to elog()
      Bootstrap mode now has a -d that requires an argument, like postmaster
      a033daf5
      History
      Commit to match discussed elog() changes. Only update is that LOG is
      Bruce Momjian authored
      now just below FATAL in server_min_messages.  Added more text to
      highlight ordering difference between it and client_min_messages.
      
      ---------------------------------------------------------------------------
      
      REALLYFATAL => PANIC
      STOP => PANIC
      New INFO level the prints to client by default
      New LOG level the prints to server log by default
      Cause VACUUM information to print only to the client
      NOTICE => INFO where purely information messages are sent
      DEBUG => LOG for purely server status messages
      DEBUG removed, kept as backward compatible
      DEBUG5, DEBUG4, DEBUG3, DEBUG2, DEBUG1 added
      DebugLvl removed in favor of new DEBUG[1-5] symbols
      New server_min_messages GUC parameter with values:
              DEBUG[5-1], INFO, NOTICE, ERROR, LOG, FATAL, PANIC
      New client_min_messages GUC parameter with values:
              DEBUG[5-1], LOG, INFO, NOTICE, ERROR, FATAL, PANIC
      Server startup now logged with LOG instead of DEBUG
      Remove debug_level GUC parameter
      elog() numbers now start at 10
      Add test to print error message if older elog() values are passed to elog()
      Bootstrap mode now has a -d that requires an argument, like postmaster
    postmaster.sgml 16.83 KiB
    <!--
    $Header: /cvsroot/pgsql/doc/src/sgml/ref/postmaster.sgml,v 1.27 2002/03/02 21:39:16 momjian Exp $
    PostgreSQL documentation
    -->
    
    <refentry id="app-postmaster">
     <docinfo>
      <date>2000-12-25</date>
     </docinfo>
    
     <refmeta>
      <refentrytitle id="APP-POSTMASTER-TITLE"><application>postmaster</application></refentrytitle>
      <manvolnum>1</manvolnum>
      <refmiscinfo>Application</refmiscinfo>
     </refmeta>
    
     <refnamediv>
      <refname id="postmaster-ref">postmaster</refname>
      <refpurpose><productname>PostgreSQL</productname> multiuser database server</refpurpose>
     </refnamediv>
    
     <refsynopsisdiv>
      <cmdsynopsis>
       <command>postmaster</command>
       <arg>-A <group choice="plain"><arg>0</arg><arg>1</arg></group></arg>
       <arg>-B <replaceable>nbuffers</replaceable></arg>
       <arg>-c <replaceable>name</replaceable>=<replaceable>value</replaceable></arg>
       <arg>-d <replaceable>debug-level</replaceable></arg>
       <arg>-D <replaceable>datadir</replaceable></arg>
       <arg>-F</arg>
       <arg>-h <replaceable>hostname</replaceable></arg>
       <arg>-i</arg>
       <arg>-k <replaceable>directory</replaceable></arg>
       <arg>-l</arg>
       <arg>-N <replaceable>max-connections</replaceable></arg>
       <arg>-o <replaceable>extra-options</replaceable></arg>
       <arg>-p <replaceable>port</replaceable></arg>
       <arg>-S</arg>
       <arg>--<replaceable>name</replaceable>=<replaceable>value</replaceable></arg>
       <group><arg>-n</arg><arg>-s</arg></group>
      </cmdsynopsis>
     </refsynopsisdiv>
    
     <refsect1>
      <title>Description</title>
    
      <para>
       <application>postmaster</application> is the
       <productname>PostgreSQL</productname> multiuser database server.
       In order for a client application to access a database it connects
       (over a network or locally) to a running
       <application>postmaster</application>.  The
       <application>postmaster</application> then starts a separate server
       process (<quote><xref linkend="app-postgres"></quote>) to handle
       the connection.  The <application>postmaster</application> also
       manages the communication among server processes.
      </para>
    
      <para>
       By default the <application>postmaster</application> starts in the
       foreground and prints log messages to the standard output.  In
       practical applications the <application>postmaster</application>
       should be started as a background process, perhaps at boot time.
      </para>
    
      <para>
       One <application>postmaster</application> always manages the data
       from exactly one database cluster.  A database cluster is a
       collection of databases that is stored at a common file system
       location.  When the postmaster starts it needs to know the location
       of the database cluster files (<quote>data area</quote>).  This is
       done with the <option>-D</option> invocation option or the
       <envar>PGDATA</envar> environment variable; there is no default.
       More than one postmaster process can run on a system at one time,
       as long as they use different data areas and different
       communication ports (see below).  A data area is created with <xref
       linkend="app-initdb">.
      </para>
    
      <refsect2 id="app-postmaster-options">
       <title>Options</title>
       <para>
        <application>postmaster</application> accepts the following
        command line arguments.  For a detailed discussion of the options
        consult the <citetitle>Administrator's Guide</citetitle>.  You can
        also save typing most of these options by setting up a
        configuration file.
        
        <variablelist>
         <varlistentry>
          <term>-A 0|1</term>
          <listitem>
           <para>
            Enables run-time assert checks, which is a debugging aid to
            detect programming mistakes.  This is only available if it was
            enabled during compilation.  If so, the default is on.
           </para>
          </listitem>
         </varlistentry>
    
         <varlistentry>
          <term>-B <replaceable class="parameter">nbuffers</replaceable></term>
          <listitem>
           <para>
    	Sets the number of shared buffers for use by the server
    	processes.  This value defaults to 64 buffers, where each
    	buffer is 8 kB.
           </para>
          </listitem>
         </varlistentry>
    
         <varlistentry>
          <term>-c <replaceable>name</replaceable>=<replaceable>value</replaceable></term>
          <listitem>
           <para>
            Sets a named run-time parameter. Consult the
            <citetitle>Administrator's Guide</citetitle> for a list and
            descriptions.  Most of the other command line options are in
            fact short forms of such a parameter assignment.  <option>-c</>
    	can appear multiple times to set multiple parameters.
           </para>
          </listitem>
         </varlistentry>
    
         <varlistentry>
          <term>-d <replaceable>debug-level</replaceable></term>
          <listitem>
           <para>
            Sets the debug level.  The higher this value is set, the more
            debugging output is written to the server log.  Values are from
    	1 to 5.
           </para>
          </listitem>
         </varlistentry>
    
         <varlistentry>
          <term>-D <replaceable class="parameter">datadir</replaceable></term>
          <listitem>
           <para>
    	Specifies the file system location of the data directory.  See
    	discussion above.
           </para>
          </listitem>
         </varlistentry>
    
         <varlistentry>
          <term>-F</term>
          <listitem>
           <para>
            Disables <function>fsync</function> calls for performance
            improvement, at the risk of data corruption in event of a
    	system crash.  Read the detailed documentation before using this!
           </para>
          </listitem>
         </varlistentry>
    
         <varlistentry>
          <term>-h <replaceable class="parameter">hostname</replaceable></term>
          <listitem>
           <para>
    	Specifies the TCP/IP host name or address on which the
    	<application>postmaster</application> is to listen for
    	connections from client applications.  Defaults to
    	listening on all configured addresses (including
            <systemitem class="systemname">localhost</systemitem>).
           </para>
          </listitem>
         </varlistentry>
    
         <varlistentry>
          <term>-i</term>
          <listitem>
           <para>
            Allows clients to connect via TCP/IP (Internet domain)
    	connections.  Without this option, only local Unix domain
    	socket connections are accepted.
           </para>
          </listitem>
         </varlistentry>
    
         <varlistentry>
          <term>-k <replaceable class="parameter">directory</replaceable></term>
          <listitem>
           <para>
    	Specifies the directory of the Unix-domain socket on which the
    	<application>postmaster</application> is to listen for
    	connections from client applications.  The default is normally
    	<filename>/tmp</filename>, but can be changed at build time.
           </para>
          </listitem>
         </varlistentry>
    
         <varlistentry>
          <term>-l</term>
          <listitem>
           <para>
    	Enables secure connections using SSL.  The <option>-i</option>
    	option is also required.  You must have compiled with SSL
    	enabled to use this option.
           </para>
          </listitem>
         </varlistentry>
    
         <varlistentry>
          <term>-N <replaceable class="parameter">max-connections</replaceable></term>
          <listitem>
           <para>
    	Sets the maximum number of client connections that this
    	<application>postmaster</application> will accept.  By
    	default, this value is 32, but it can be set as high as your
    	system will support.  (Note that
    	<option>-B</option> is required to be at least twice
    	<option>-N</option>.  See the <citetitle>Administrator's
    	Guide</citetitle> for a discussion of system resource requirements
    	for large numbers of client connections.)
           </para>
          </listitem>
         </varlistentry>
    
         <varlistentry>
          <term>-o <replaceable class="parameter">extra-options</replaceable></term>
          <listitem>
           <para>
    	The command line-style options specified in <replaceable
    	class="parameter">extra-options</replaceable> are passed to
    	all backend server processes started by this
    	<application>postmaster</application>.  See <xref
    	linkend="app-postgres"> for possibilities.  If the option
    	string contains any spaces, the entire string must be quoted.
           </para>
          </listitem>
         </varlistentry>
    
         <varlistentry>
          <term>-p <replaceable class="parameter">port</replaceable></term>
          <listitem>
           <para>
    	Specifies the TCP/IP port or local Unix domain socket file
    	extension on which the <application>postmaster</application>
    	is to listen for connections from client applications.
    	Defaults to the value of the <envar>PGPORT</envar> environment
    	variable, or if <envar>PGPORT</envar> is not set, then
    	defaults to the value established during compilation (normally
    	5432).  If you specify a port other than the default port,
    	then all client applications must specify the same port using
    	either command-line options or <envar>PGPORT</envar>.
           </para>
          </listitem>
         </varlistentry>
    
         <varlistentry>
          <term>-S</term>
          <listitem>
           <para>
    	Specifies that the <application>postmaster</application>
    	process should start up in silent mode.  That is, it will
    	disassociate from the user's (controlling) terminal, start its
    	own process group, and redirect its standard output and
    	standard error to <filename>/dev/null</filename>.
           </para>
           <para>
            Using this switch discards all logging output, which is
    	probably not what you want, since it makes it very difficult
    	to troubleshoot problems.  See below for a better way to start
    	the <application>postmaster</application> in the background.
           </para>
          </listitem>
         </varlistentry>
    
         <varlistentry>
          <term>--<replaceable>name</replaceable>=<replaceable>value</replaceable></term>
          <listitem>
           <para>
            Sets a named run-time parameter; a shorter form of
            <option>-c</>.
           </para>
          </listitem>
         </varlistentry>
    
        </variablelist>
       </para>
    
       <para>
        Two additional command line options are available for debugging
        problems that cause a backend to die abnormally.  These options
        control the behavior of the <application>postmaster</application>
        in this situation, and <emphasis>neither option is intended for
        use in ordinary operation</emphasis>.
       </para>
    
       <para>
        The ordinary strategy for this situation is to notify all other
        backends that they must terminate and then reinitialize the shared
        memory and semaphores.  This is because an errant backend could
        have corrupted some shared state before terminating.
       </para>
    
       <para>
        These special-case options are:
    
        <variablelist>
         <varlistentry>
          <term>-n</term>
          <listitem>
           <para>
    	<application>postmaster</application>
    	will not reinitialize shared data structures.  A knowledgeable system
    	programmer can then use a debugger
    	to examine shared memory and semaphore state.
           </para>
         </listitem>
        </varlistentry>
    
        <varlistentry>
          <term>-s</term>
          <listitem>
           <para>
    	<application>postmaster</application>
    	will stop all other backend processes by sending the signal
    	<literal>SIGSTOP</literal>,
    	but will not cause them to terminate.  This permits system programmers
    	to collect core dumps from all backend processes by hand.
           </para>
          </listitem>
         </varlistentry>
        </variablelist>
       </para>
      </refsect2>
    
      <refsect2 id="R2-APP-POSTMASTER-2">
       <title>
        Outputs
       </title>
       <para>
    
        <variablelist>
         <varlistentry>
          <term><computeroutput>
    semget: No space left on device
           </computeroutput></term>
          <listitem>
           <para>
    	If you see this message, you should run the
    	<application>ipcclean</application>
    	command.  After doing so, try starting
    	<application>postmaster</application>
    	again.  If this still doesn't work, you probably need to configure
    	your kernel for shared memory and semaphores as described in the
    	installation notes.  If you run multiple instances of
    	<application>postmaster</application>
    	on a single host, or have a kernel with particularly small shared memory
    	and/or semaphore limits, you may have to reconfigure your kernel to increase
    	its shared memory or semaphore parameters.
    
    	<tip>
    	 <para>
    	  You may be able to postpone
    	  reconfiguring your kernel by decreasing <option>-B</option> to reduce
    	  the shared memory consumption of <productname>PostgreSQL</>,
    	  and/or by reducing <option>-N</option> to reduce the semaphore
    	  consumption.
    	 </para>
    	</tip>
           </para>
          </listitem>
         </varlistentry>
    
         <varlistentry>
          <term><computeroutput>
    StreamServerPort: cannot bind to port
           </computeroutput></term>
          <listitem>
           <para>
    	If you see this message, you should make certain that there is no
    	other <application>postmaster</application>
    	process already running on the same port number.  The easiest way to
    	determine this is by using the command
    <screen>
    <prompt>$</prompt> <userinput>ps ax | grep postmaster</userinput>
    </screen>
            or
    <screen>
    <prompt>$</prompt> <userinput>ps -e | grep postmaster</userinput>
    </screen>
    	depending on your system.
           </para>
    
           <para>
    	If you 
    	are sure that no other
    	<application>postmaster</application>
    	processes are running and you still get this error, try specifying a
    	different port using the
    	<literal>-p</literal>
    	option.  You may also get this error if you terminate the
    	<application>postmaster</application>
    	and immediately restart it using the same port; in this case, you must
    	simply wait a few seconds until the operating system closes the port
    	before trying again.  Finally, you may get this error if you specify
    	a port number that your operating system considers to be reserved.
    	For example, many versions of Unix consider port numbers under 1024 to
    	be <firstterm>trusted</firstterm>
    	and only permit the Unix superuser to access them.
           </para>
          </listitem>
         </varlistentry>
        </variablelist>
       </para>
      </refsect2>
     </refsect1>
    
     <refsect1>
      <title>Notes</title>
      
      <para>
       If at all possible, <emphasis>do not</emphasis> use
       <literal>SIGKILL</literal> to kill the
       <application>postmaster</application>.  This will prevent
       <application>postmaster</application> from freeing the system
       resources (e.g., shared memory and semaphores) that it holds before
       terminating.
      </para>
    
      <para>
       To terminate the <application>postmaster</application> normally,
       the signals <literal>SIGTERM</literal>, <literal>SIGINT</literal>,
       or <literal>SIGQUIT</literal> can be used.  The first will wait for
       all clients to terminate before quitting, the second will
       forcefully disconnect all clients, and the third will quit
       immediately without proper shutdown, resulting in a recovery run
       during restart.
      </para>
    
      <para>
       The utility command <xref linkend="app-pg-ctl"> can be used to
       start and shut down the <application>postmaster</application>
       safely and comfortably.
      </para>
    
      <para>
       The <option>--</> options will not work on FreeBSD or OpenBSD.
       Use <option>-c</> instead. This is a bug in the affected operating
       systems; a future release of <productname>PostgreSQL</productname> will
       provide a workaround if this is not fixed.
      </para>
    
     </refsect1>
    
     <refsect1 id="app-postmaster-usage">
      <title>Usage</title>
      <para>
       To start <application>postmaster</application> in the background
       using default values, type:
    
    <screen>
    <prompt>$</prompt> <userinput>nohup postmaster &gt;logfile 2&gt;&amp;1 &lt;/dev/null &amp;</userinput>
    </screen>
      </para>
    
      <para>
       To start <application>postmaster</application> with a specific
       port:
    <screen>
    <prompt>$</prompt> <userinput>postmaster -p 1234</userinput>
    </screen>
       This command will start up <application>postmaster</application>
       communicating through the port 1234. In order to connect to this
       <application>postmaster</application> using psql, you would need to
       run it as
    <screen>
    <prompt>$</prompt> <userinput>psql -p 1234</userinput>
    </screen>
       or set the environment variable <envar>PGPORT</envar>:
    <screen>
    <prompt>$</prompt> <userinput>export PGPORT=1234</userinput>
    <prompt>$</prompt> <userinput>psql</userinput>
    </screen>
      </para>
    
      <para>
       Named runtime parameters can be set in either of these styles:
    <screen>
    <prompt>$</prompt> <userinput>postmaster -c sort_mem=1234</userinput>
    <prompt>$</prompt> <userinput>postmaster --sort-mem=1234</userinput>
    </screen>
       Either form overrides whatever setting might exist for <literal>sort_mem</>
       in <filename>postgresql.conf</>.  Notice that underscores in parameter
       names can be written as either underscore or dash on the command line.
      </para>
    
      <tip>
      <para>
       Except for short-term experiments,
       it's probably better practice to edit the setting in
       <filename>postgresql.conf</> than to rely on a command-line switch
       to set a parameter.
      </para>
      </tip>
     </refsect1>
    </refentry>
    
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