postmaster.sgml

PostgreSQL7.4.6 for Linux

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$Header: /cvsroot/pgsql/doc/src/sgml/ref/postmaster.sgml,v 1.41 2003/10/16 17:38:01 momjian Exp $
PostgreSQL documentation
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<refentry id="app-postmaster">
 <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>

 <indexterm zone="app-postmaster">
  <primary>postmaster</primary>
 </indexterm>

 <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>
   <command>postmaster</command> 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
   <command>postmaster</command>.  The
   <command>postmaster</command> then starts a separate server
   process (<quote><xref linkend="app-postgres"></quote>) to handle
   the connection.  The <command>postmaster</command> also
   manages the communication among server processes.
  </para>

  <para>
   By default the <command>postmaster</command> starts in the
   foreground and prints log messages to the standard error stream.  In
   practical applications the <command>postmaster</command>
   should be started as a background process, perhaps at boot time.
  </para>

  <para>
   One <command>postmaster</command> 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 <command>postmaster</command> 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 <command>postmaster</command> 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>
 </refsect1>

 <refsect1 id="app-postmaster-options">
  <title>Options</title>

   <para>
    <command>postmaster</command> accepts the following
    command line arguments.  For a detailed discussion of the options
    consult <xref linkend="runtime-config">.  You can also save typing most of these
    options by setting up a configuration file.
    
    <variablelist>
     <varlistentry>
      <term><option>-A 0|1</option></term>
      <listitem>
       <para>
        Enables run-time assertion 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><option>-B <replaceable class="parameter">nbuffers</replaceable></option></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><option>-c <replaceable>name</replaceable>=<replaceable>value</replaceable></option></term>
      <listitem>
       <para>
        Sets a named run-time parameter. Consult <xref linkend="runtime-config"> 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><option>-d <replaceable>debug-level</replaceable></option></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><option>-D <replaceable class="parameter">datadir</replaceable></option></term>
      <listitem>
       <para>
	Specifies the file system location of the data directory.  See
	discussion above.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-F</option></term>
      <listitem>
       <para>
        Disables <function>fsync</function> calls for performance
        improvement, at the risk of data corruption in event of a
        system crash.  This option corresponds to setting
        <literal>fsync=false</> in <filename>postgresql.conf</>. Read the detailed
        documentation before using this!
       </para>
       <para>
        <option>--fsync=true</option> has the opposite effect
        of this option.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-h <replaceable class="parameter">hostname</replaceable></option></term>
      <listitem>
       <para>
	Specifies the IP host name or address on which the
	<command>postmaster</command> 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><option>-i</option></term>
      <listitem>
       <para>
        Allows clients to connect via TCP/IP (Internet domain)
	connections.  Without this option, only local Unix domain
        socket connections are accepted. This option corresponds
        to setting <literal>tcpip_socket=true</> in <filename>postgresql.conf</>.
       </para>
       <para>
        <option>--tcpip-socket=false</option> has the opposite
        effect of this option.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-k <replaceable class="parameter">directory</replaceable></option></term>
      <listitem>
       <para>
	Specifies the directory of the Unix-domain socket on which the
	<command>postmaster</command> 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><option>-l</option></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><option>-N <replaceable class="parameter">max-connections</replaceable></option></term>
      <listitem>
       <para>
	Sets the maximum number of client connections that this
	<command>postmaster</command> 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 <xref linkend="kernel-resources"> for a discussion of
	system resource requirements for large numbers of client
	connections.)
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-o <replaceable class="parameter">extra-options</replaceable></option></term>
      <listitem>
       <para>
	The command line-style options specified in <replaceable
	class="parameter">extra-options</replaceable> are passed to
	all server processes started by this
	<command>postmaster</command>.  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><option>-p <replaceable class="parameter">port</replaceable></option></term>
      <listitem>
       <para>
	Specifies the TCP/IP port or local Unix domain socket file
	extension on which the <command>postmaster</command>
	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><option>-S</option></term>
      <listitem>
       <para>
	Specifies that the <command>postmaster</command>
	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 <command>postmaster</command> in the background.
       </para>
       <para>
        <option>--silent-mode=false</option> has the opposite effect
        of this option.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>--<replaceable>name</replaceable>=<replaceable>value</replaceable></option></term>
      <listitem>
       <para>
        Sets a named run-time parameter; a shorter form of
        <option>-c</>.
       </para>
      </listitem>
     </varlistentry>