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600 lines
19 KiB
Plaintext
<!--
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$Header: /cvsroot/pgsql/doc/src/sgml/ref/postmaster.sgml,v 1.31 2002/07/28 15:22:21 petere Exp $
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PostgreSQL documentation
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-->
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<refentry id="app-postmaster">
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<refmeta>
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<refentrytitle id="APP-POSTMASTER-TITLE"><application>postmaster</application></refentrytitle>
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<manvolnum>1</manvolnum>
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<refmiscinfo>Application</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname id="postmaster-ref">postmaster</refname>
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<refpurpose><productname>PostgreSQL</productname> multiuser database server</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<cmdsynopsis>
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<command>postmaster</command>
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<arg>-A <group choice="plain"><arg>0</arg><arg>1</arg></group></arg>
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<arg>-B <replaceable>nbuffers</replaceable></arg>
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<arg>-c <replaceable>name</replaceable>=<replaceable>value</replaceable></arg>
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<arg>-d <replaceable>debug-level</replaceable></arg>
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<arg>-D <replaceable>datadir</replaceable></arg>
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<arg>-F</arg>
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<arg>-h <replaceable>hostname</replaceable></arg>
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<arg>-i</arg>
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<arg>-k <replaceable>directory</replaceable></arg>
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<arg>-l</arg>
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<arg>-N <replaceable>max-connections</replaceable></arg>
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<arg>-o <replaceable>extra-options</replaceable></arg>
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<arg>-p <replaceable>port</replaceable></arg>
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<arg>-S</arg>
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<arg>--<replaceable>name</replaceable>=<replaceable>value</replaceable></arg>
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<group><arg>-n</arg><arg>-s</arg></group>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>
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<application>postmaster</application> is the
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<productname>PostgreSQL</productname> multiuser database server.
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In order for a client application to access a database it connects
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(over a network or locally) to a running
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<application>postmaster</application>. The
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<application>postmaster</application> then starts a separate server
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process (<quote><xref linkend="app-postgres"></quote>) to handle
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the connection. The <application>postmaster</application> also
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manages the communication among server processes.
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</para>
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<para>
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By default the <application>postmaster</application> starts in the
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foreground and prints log messages to the standard output. In
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practical applications the <application>postmaster</application>
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should be started as a background process, perhaps at boot time.
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</para>
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<para>
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One <application>postmaster</application> always manages the data
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from exactly one database cluster. A database cluster is a
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collection of databases that is stored at a common file system
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location. When the postmaster starts it needs to know the location
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of the database cluster files (<quote>data area</quote>). This is
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done with the <option>-D</option> invocation option or the
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<envar>PGDATA</envar> environment variable; there is no default.
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More than one postmaster process can run on a system at one time,
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as long as they use different data areas and different
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communication ports (see below). A data area is created with <xref
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linkend="app-initdb">.
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</para>
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<refsect2 id="app-postmaster-options">
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<title>Options</title>
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<para>
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<application>postmaster</application> accepts the following
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command line arguments. For a detailed discussion of the options
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consult the <citetitle>Administrator's Guide</citetitle>. You can
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also save typing most of these options by setting up a
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configuration file.
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<variablelist>
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<varlistentry>
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<term>-A 0|1</term>
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<listitem>
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<para>
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Enables run-time assert checks, which is a debugging aid to
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detect programming mistakes. This is only available if it was
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enabled during compilation. If so, the default is on.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>-B <replaceable class="parameter">nbuffers</replaceable></term>
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<listitem>
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<para>
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Sets the number of shared buffers for use by the server
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processes. This value defaults to 64 buffers, where each
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buffer is 8 kB.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>-c <replaceable>name</replaceable>=<replaceable>value</replaceable></term>
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<listitem>
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<para>
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Sets a named run-time parameter. Consult the
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<citetitle>Administrator's Guide</citetitle> for a list and
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descriptions. Most of the other command line options are in
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fact short forms of such a parameter assignment. <option>-c</>
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can appear multiple times to set multiple parameters.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>-d <replaceable>debug-level</replaceable></term>
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<listitem>
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<para>
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Sets the debug level. The higher this value is set, the more
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debugging output is written to the server log. Values are from
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1 to 5.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>-D <replaceable class="parameter">datadir</replaceable></term>
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<listitem>
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<para>
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Specifies the file system location of the data directory. See
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discussion above.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>-F</term>
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<listitem>
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<para>
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Disables <function>fsync</function> calls for performance
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improvement, at the risk of data corruption in event of a
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system crash. This parameter corresponds to setting
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fsync=false in postgresql.conf. Read the detailed
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documentation before using this!
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</para>
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<para>
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<option>--fsync=true</option> has the opposite effect
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of this option.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>-h <replaceable class="parameter">hostname</replaceable></term>
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<listitem>
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<para>
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Specifies the TCP/IP host name or address on which the
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<application>postmaster</application> is to listen for
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connections from client applications. Defaults to
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listening on all configured addresses (including
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<systemitem class="systemname">localhost</systemitem>).
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>-i</term>
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<listitem>
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<para>
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Allows clients to connect via TCP/IP (Internet domain)
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connections. Without this option, only local Unix domain
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socket connections are accepted. This option corresponds
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to setting tcpip_socket=true in postgresql.conf.
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</para>
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<para>
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<option>--tcpip_socket=false</option> has the opposite
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effect of this option.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>-k <replaceable class="parameter">directory</replaceable></term>
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<listitem>
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<para>
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Specifies the directory of the Unix-domain socket on which the
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<application>postmaster</application> is to listen for
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connections from client applications. The default is normally
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<filename>/tmp</filename>, but can be changed at build time.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>-l</term>
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<listitem>
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<para>
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Enables secure connections using SSL. The <option>-i</option>
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option is also required. You must have compiled with SSL
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enabled to use this option.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>-N <replaceable class="parameter">max-connections</replaceable></term>
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<listitem>
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<para>
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Sets the maximum number of client connections that this
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<application>postmaster</application> will accept. By
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default, this value is 32, but it can be set as high as your
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system will support. (Note that
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<option>-B</option> is required to be at least twice
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<option>-N</option>. See the <citetitle>Administrator's
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Guide</citetitle> for a discussion of system resource requirements
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for large numbers of client connections.)
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>-o <replaceable class="parameter">extra-options</replaceable></term>
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<listitem>
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<para>
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The command line-style options specified in <replaceable
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class="parameter">extra-options</replaceable> are passed to
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all backend server processes started by this
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<application>postmaster</application>. See <xref
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linkend="app-postgres"> for possibilities. If the option
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string contains any spaces, the entire string must be quoted.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>-p <replaceable class="parameter">port</replaceable></term>
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<listitem>
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<para>
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Specifies the TCP/IP port or local Unix domain socket file
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extension on which the <application>postmaster</application>
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is to listen for connections from client applications.
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Defaults to the value of the <envar>PGPORT</envar> environment
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variable, or if <envar>PGPORT</envar> is not set, then
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defaults to the value established during compilation (normally
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5432). If you specify a port other than the default port,
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then all client applications must specify the same port using
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either command-line options or <envar>PGPORT</envar>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>-S</term>
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<listitem>
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<para>
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Specifies that the <application>postmaster</application>
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process should start up in silent mode. That is, it will
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disassociate from the user's (controlling) terminal, start its
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own process group, and redirect its standard output and
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standard error to <filename>/dev/null</filename>.
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</para>
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<para>
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Using this switch discards all logging output, which is
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probably not what you want, since it makes it very difficult
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to troubleshoot problems. See below for a better way to start
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the <application>postmaster</application> in the background.
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</para>
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<para>
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<option>--silent_mode=false</option> has the opposite effect
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of this option.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>--<replaceable>name</replaceable>=<replaceable>value</replaceable></term>
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<listitem>
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<para>
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Sets a named run-time parameter; a shorter form of
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<option>-c</>.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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<para>
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Two additional command line options are available for debugging
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problems that cause a backend to die abnormally. These options
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control the behavior of the <application>postmaster</application>
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in this situation, and <emphasis>neither option is intended for
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use in ordinary operation</emphasis>.
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</para>
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<para>
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The ordinary strategy for this situation is to notify all other
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backends that they must terminate and then reinitialize the shared
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memory and semaphores. This is because an errant backend could
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have corrupted some shared state before terminating.
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</para>
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<para>
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These special-case options are:
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<variablelist>
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<varlistentry>
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<term>-n</term>
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<listitem>
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<para>
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<application>postmaster</application>
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will not reinitialize shared data structures. A knowledgeable system
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programmer can then use a debugger
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to examine shared memory and semaphore state.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>-s</term>
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<listitem>
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<para>
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<application>postmaster</application>
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will stop all other backend processes by sending the signal
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<literal>SIGSTOP</literal>,
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but will not cause them to terminate. This permits system programmers
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to collect core dumps from all backend processes by hand.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</refsect2>
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</refsect1>
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<refsect1>
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<title>Environment</title>
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<variablelist>
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<varlistentry>
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<term><envar>PGCLIENTENCODING</envar></term>
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<listitem>
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<para>
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Default character encoding used by clients. (The clients may
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override this invidiually.) This value can also be set in the
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configuration file.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><envar>PGDATA</envar></term>
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<listitem>
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<para>
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Default data direction location
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><envar>PGDATASTYLE</envar></term>
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<listitem>
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<para>
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Default value of the <literal>datestyle</literal> run-time
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parameter. (The use of this environment variable is deprecated.)
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><envar>PGPORT</envar></term>
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<listitem>
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<para>
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Default port (preferrably set in the configuration file)
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><envar>TZ</envar></term>
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<listitem>
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<para>
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Server time zone
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>others</term>
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<listitem>
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<para>
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Other environment variables may be used to designate alternative
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data storage locations. See the <citetitle>Administrator's
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Guide</citetitle> for more information.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Diagnostics</title>
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<para>
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<variablelist>
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<varlistentry>
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<term><computeroutput>
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semget: No space left on device
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</computeroutput></term>
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<listitem>
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<para>
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If you see this message, you should run the
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<application>ipcclean</application>
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command. After doing so, try starting
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<application>postmaster</application>
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again. If this still doesn't work, you probably need to configure
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your kernel for shared memory and semaphores as described in the
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installation notes. If you run multiple instances of
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<application>postmaster</application>
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on a single host, or have a kernel with particularly small shared memory
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and/or semaphore limits, you may have to reconfigure your kernel to increase
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its shared memory or semaphore parameters.
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<tip>
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<para>
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You may be able to postpone
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reconfiguring your kernel by decreasing <option>-B</option> to reduce
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the shared memory consumption of <productname>PostgreSQL</>,
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and/or by reducing <option>-N</option> to reduce the semaphore
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consumption.
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</para>
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</tip>
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</para>
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</listitem>
|
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</varlistentry>
|
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|
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<varlistentry>
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<term><computeroutput>
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StreamServerPort: cannot bind to port
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</computeroutput></term>
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<listitem>
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<para>
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If you see this message, you should make certain that there is no
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other <application>postmaster</application>
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process already running on the same port number. The easiest way to
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determine this is by using the command
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<screen>
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<prompt>$</prompt> <userinput>ps ax | grep postmaster</userinput>
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</screen>
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or
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<screen>
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<prompt>$</prompt> <userinput>ps -e | grep postmaster</userinput>
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</screen>
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depending on your system.
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</para>
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<para>
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If you
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are sure that no other
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<application>postmaster</application>
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processes are running and you still get this error, try specifying a
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different port using the
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<literal>-p</literal>
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option. You may also get this error if you terminate the
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<application>postmaster</application>
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and immediately restart it using the same port; in this case, you must
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simply wait a few seconds until the operating system closes the port
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before trying again. Finally, you may get this error if you specify
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a port number that your operating system considers to be reserved.
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For example, many versions of Unix consider port numbers under 1024 to
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be <firstterm>trusted</firstterm>
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and only permit the Unix superuser to access them.
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</para>
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</listitem>
|
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</varlistentry>
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</variablelist>
|
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</para>
|
|
</refsect1>
|
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|
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<refsect1>
|
|
<title>Notes</title>
|
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|
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<para>
|
|
If at all possible, <emphasis>do not</emphasis> use
|
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<literal>SIGKILL</literal> to kill the
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<application>postmaster</application>. This will prevent
|
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<application>postmaster</application> from freeing the system
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resources (e.g., shared memory and semaphores) that it holds before
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terminating.
|
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</para>
|
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|
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<para>
|
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To terminate the <application>postmaster</application> normally,
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the signals <literal>SIGTERM</literal>, <literal>SIGINT</literal>,
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or <literal>SIGQUIT</literal> can be used. The first will wait for
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all clients to terminate before quitting, the second will
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forcefully disconnect all clients, and the third will quit
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immediately without proper shutdown, resulting in a recovery run
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during restart.
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</para>
|
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|
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<para>
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The utility command <xref linkend="app-pg-ctl"> can be used to
|
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start and shut down the <application>postmaster</application>
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safely and comfortably.
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</para>
|
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<para>
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The <option>--</> options will not work on FreeBSD or OpenBSD.
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Use <option>-c</> instead. This is a bug in the affected operating
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systems; a future release of <productname>PostgreSQL</productname> will
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provide a workaround if this is not fixed.
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</para>
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|
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</refsect1>
|
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|
|
<refsect1 id="app-postmaster-examples">
|
|
<title>Examples</title>
|
|
<para>
|
|
To start <application>postmaster</application> in the background
|
|
using default values, type:
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|
|
<screen>
|
|
<prompt>$</prompt> <userinput>nohup postmaster >logfile 2>&1 </dev/null &</userinput>
|
|
</screen>
|
|
</para>
|
|
|
|
<para>
|
|
To start <application>postmaster</application> with a specific
|
|
port:
|
|
<screen>
|
|
<prompt>$</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>$</prompt> <userinput>psql</userinput>
|
|
</screen>
|
|
</para>
|
|
|
|
<para>
|
|
Named run-time parameters can be set in either of these styles:
|
|
<screen>
|
|
<prompt>$</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>
|
|
|
|
<!-- Keep this comment at the end of the file
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|
Local variables:
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mode: sgml
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sgml-omittag:nil
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|
sgml-shorttag:t
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|
sgml-minimize-attributes:nil
|
|
sgml-always-quote-attributes:t
|
|
sgml-indent-step:1
|
|
sgml-indent-data:t
|
|
sgml-parent-document:nil
|
|
sgml-default-dtd-file:"../reference.ced"
|
|
sgml-exposed-tags:nil
|
|
sgml-local-catalogs:"/usr/lib/sgml/catalog"
|
|
sgml-local-ecat-files:nil
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|
End:
|
|
-->
|