postmaster.sgml

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

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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 (the <quote>data area</quote>).
   More than one <command>postmaster</command> process can run on a system
   at one time, so long as they use different data areas and different
   communication ports (see below).  A data area is created with <xref
   linkend="app-initdb">.
  </para>

  <para>
   When the <command>postmaster</command> starts it needs 
   to know the location of the data area.
   The location must be specified by the <option>-D</option> option
   or the <envar>PGDATA</envar> environment variable; there is no default.
   Typically, <option>-D</option> or <envar>PGDATA</envar> points
   directly to the data area directory created by <application>initdb</>.
   Other possible file layouts are discussed in
   <xref linkend="runtime-config-file-locations">.
  </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 option is only available if
        assertions were enabled when <productname>PostgreSQL</> was
        compiled. 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.  The default value of this parameter is chosen
	automatically by <application>initdb</application>; refer to <xref
	linkend="runtime-config-resource-memory"> for more information.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-c <replaceable>name</replaceable>=<replaceable>value</replaceable></option></term>
      <listitem>
       <para>
        Sets a named run-time parameter. The configuration parameters
        supported by <productname>PostgreSQL</productname> are
        described in <xref linkend="runtime-config">. 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 or
        configuration file(s).  See
        <xref linkend="runtime-config-file-locations"> for details.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-F</option></term>
      <listitem>
       <para>
        Disables <function>fsync</function> calls for improved
        performance, at the risk of data corruption in the event of a
        system crash.  Specifying this option is equivalent to
        disabling the <xref linkend="guc-fsync"> configuration
        parameter. 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 TCP/IP
        connections from client applications.  The value can also be a
        comma-separated list of addresses, or <literal>*</> to specify
        listening on all available interfaces.  An empty value
        specifies not listening on any IP addresses, in which case
        only Unix-domain sockets can be used to connect to the
        <command>postmaster</command>.  Defaults to listening only on
        <systemitem class="systemname">localhost</systemitem>.
        Specifying this option is equivalent to setting the <xref
        linkend="guc-listen-addresses"> configuration parameter.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-i</option></term>
      <listitem>
       <para>
        Allows remote clients to connect via TCP/IP (Internet domain)
        connections.  Without this option, only local connections are
        accepted.  This option is equivalent to setting
        <varname>listen_addresses</> to <literal>*</> in
        <filename>postgresql.conf</> or via <option>-h</>.
       </para>
       <para>
        This option is deprecated since it does not allow access to the
        full functionality of <xref linkend="guc-listen-addresses">.
        It's usually better to set <varname>listen_addresses</> directly.
       </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 <acronym>SSL</acronym>.
	<productname>PostgreSQL</productname> must have been compiled with
	support for <acronym>SSL</acronym> for this option to be
	available. For more information on using <acronym>SSL</acronym>,
	refer to <xref linkend="ssl-tcp">.
       </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.) Specifying this option is equivalent to setting the
	<xref linkend="guc-max-connections"> configuration parameter.
       </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.