1999-05-26 19:25:38 +02:00
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<refentry id="APP-POSTMASTER">
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<refmeta>
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<refentrytitle>
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<application>postmaster</application>
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</refentrytitle>
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<refmiscinfo>Application</refmiscinfo>
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</refmeta>
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<refnamediv>
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1999-05-27 17:49:15 +02:00
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<refname id="postmaster-ref">
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1999-05-26 19:25:38 +02:00
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<application>postmaster</application>
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</refname>
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<refpurpose>
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Run the <productname>Postgres</productname> multi-user backend
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</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<refsynopsisdivinfo>
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<date>1999-05-19</date>
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</refsynopsisdivinfo>
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<synopsis>
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1999-05-27 17:49:15 +02:00
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postmaster [ -B <replaceable class="parameter">nBuffers</replaceable> ] [ -D <replaceable class="parameter">DataDir</replaceable> ] [ -i ]
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postmaster [ -B <replaceable class="parameter">nBuffers</replaceable> ] [ -D <replaceable class="parameter">DataDir</replaceable> ] [ -N <replaceable class="parameter">nBackends</replaceable> ] [ -S ]
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[ -d [ <replaceable class="parameter">DebugLevel</replaceable> ] [ -i ] [ -o <replaceable class="parameter">BackendOptions</replaceable> ] [ -p <replaceable class="parameter">port</replaceable> ]
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1999-05-26 19:25:38 +02:00
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postmaster [ -n | -s ] ...
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</synopsis>
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<refsect2 id="R2-APP-POSTMASTER-1">
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<refsect2info>
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<date>1999-05-19</date>
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</refsect2info>
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<title>
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Inputs
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</title>
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<para>
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<application>postmaster</application> accepts the following command line arguments:
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<variablelist>
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<varlistentry>
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<term>
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-B <replaceable class="parameter">nBuffers</replaceable>
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</term>
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<listitem>
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<para>
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The number of shared-memory buffers for the
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<application>postmaster</application>
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to allocate and manage for the backend server processes that it
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starts. This value defaults to 64 buffers, where each buffer is 8k bytes
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(or whatever BLCKSZ is set to in config.h).
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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>
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-D <replaceable class="parameter">DataDir</replaceable>
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</term>
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<listitem>
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<para>
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Specifies the directory to use as the root of the tree of database
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directories. If -D is not given, the default data directory name is
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the value of the environment variable
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<envar>PGDATA</envar>.
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If <envar>PGDATA</envar> is not set, then the directory used is
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<filename>$POSTGRESHOME/data</filename>.
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If neither environment variable is set and this command-line
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option is not specified, the default directory that was
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set at compile-time is used.
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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>
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-N <replaceable class="parameter">nBackends</replaceable>
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</term>
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<listitem>
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<para>
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The maximum number of backend server processes that this postmaster
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is allowed to start. In the default configuration, this value
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is usually set
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to 32, and can be set as high as 1024 if your system will support that
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many processes. Both the default and upper limit values can be altered
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when building <productname>Postgres</productname> (see src/include/config.h).
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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>
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-S
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</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 disassociate
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from the user's (controlling) tty and start its own process group.
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This should not be used in combination with debugging options because
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any messages printed to standard output and standard error are
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discarded.
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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>
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-d [ <replaceable class="parameter">DebugLevel</replaceable> ]
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</term>
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<listitem>
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<para>
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The optional argument <replaceable class="parameter">DebugLevel</replaceable>
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determines the amount of debugging output the backend servers will
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produce.
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If <replaceable class="parameter">DebugLevel</replaceable>
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is one, the postmaster will trace all connection traffic,
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and nothing else.
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For levels two and higher,
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debugging is turned on in the backend process and the postmaster
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displays more information,
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including the backend environment and process traffic.
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Note that if no file is specified for backend servers to
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send their debugging output then this output will appear on the
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controlling tty of their parent <application>postmaster</application>.
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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>
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-i
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</term>
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<listitem>
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<para>
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This enables TCP/IP or Internet domain socket communication.
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Without this option, only local Unix domain socket communication is
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possible.
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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>
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-o <replaceable class="parameter">BackendOptions</replaceable>
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</term>
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<listitem>
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<para>
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The
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<literal>postgres</literal>
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options specified in
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<replaceable class="parameter">BackendOptions</replaceable>
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are passed to all backend server processes started by this
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<application>postmaster</application>.
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If the option string contains any spaces, the entire string must be
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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>
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-p <replaceable class="parameter">port</replaceable>
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</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 extension
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on which the <application>postmaster</application>
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is to listen for connections from frontend applications. Defaults to
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the value of the
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<envar>PGPORT</envar>
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environment variable, or if <envar>PGPORT</envar>
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is not set, then defaults to the value established when Postgres was
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compiled (normally 5432). If you specify a port other than the
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default port then all frontend applications (including
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<application>psql</application>) must specify the same
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port using either command-line options or
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<envar>PGPORT</envar>.
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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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A few command line options are available for debugging in the case
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when a backend dies abnormally.
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These options control the behavior of the
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<application>postmaster</application> in this situation, and
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<emphasis>neither option is intended for use in
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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 have
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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>
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-n
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</term>
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<listitem>
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<para>
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<application>postmaster</application>
|
1999-05-27 17:49:15 +02:00
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will not reinitialize shared data structures. A knowledgable system
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1999-05-26 19:25:38 +02:00
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programmer can then use the
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<application>shmemdoc</application>
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program 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>
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-s
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</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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|
1999-05-27 17:49:15 +02:00
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|
|
<refsect2 id="R2-APP-POSTMASTER-2">
|
1999-05-26 19:25:38 +02:00
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<refsect2info>
|
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<date>1999-05-19</date>
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</refsect2info>
|
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<title>
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Outputs
|
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</title>
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<para>
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<variablelist>
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<!--
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<varlistentry>
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<term>
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FindBackend: could not find a backend to execute...
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</term>
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<listitem>
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<para>
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If you see this message, you do not have the
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<application>postgres</application>
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executable in your path. Add the directory in which
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<application>postgres</application> resides to
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your path.
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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>
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semget: No space left on device
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</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 this, 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 -B to reduce
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<productname>Postgres</productname>' shared memory
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consumption, or by reducing -N to reduce Postgres' 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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<varlistentry>
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<term>
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StreamServerPort: cannot bind to port
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</term>
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<listitem>
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<para>
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If you see this message, you should be certain that there is no other
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<application>postmaster</application>
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process already running. The easiest way to determine this is by
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using the command
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|
|
|
<programlisting>
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% ps -ax | grep postmaster
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</programlisting>
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on BSD-based systems, or
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<programlisting>
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% ps -e | grep postmast
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</programlisting>
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for System V-like or POSIX-compliant systems such as HP-UX.
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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
|
|
|
|
be <firstterm>trusted</firstterm>
|
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|
|
and only permit the Unix superuser to access them.
|
|
|
|
</para>
|
|
|
|
</listitem>
|
|
|
|
</varlistentry>
|
|
|
|
|
|
|
|
<varlistentry>
|
|
|
|
<term>
|
|
|
|
IpcMemoryAttach: shmat() failed: Permission denied
|
|
|
|
</term>
|
|
|
|
<listitem>
|
|
|
|
<para>
|
|
|
|
A likely explanation is that another user attempted to start a
|
|
|
|
<application>postmaster</application>
|
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|
|
process on the same port which acquired shared resources and then
|
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|
|
died. Since Postgres shared memory keys are based on the port number
|
|
|
|
assigned to the
|
|
|
|
<application>postmaster</application>,
|
|
|
|
such conflicts are likely if there is more than one installation on
|
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|
|
a single host. If there are no other
|
|
|
|
<application>postmaster</application>
|
|
|
|
processes currently running (see above), run
|
|
|
|
<application>ipcclean</application>
|
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|
|
and try again. If other <application>postmaster</application>
|
|
|
|
images
|
|
|
|
are running, you will have to find the owners of those processes to
|
|
|
|
coordinate the assignment of port numbers and/or removal of unused
|
|
|
|
shared memory segments.
|
|
|
|
</para>
|
|
|
|
</listitem>
|
|
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
|
|
</para>
|
|
|
|
</refsect2>
|
|
|
|
</refsynopsisdiv>
|
|
|
|
|
|
|
|
<refsect1 id="R1-APP-POSTMASTER-1">
|
|
|
|
<refsect1info>
|
|
|
|
<date>1999-05-19</date>
|
|
|
|
</refsect1info>
|
|
|
|
<title>
|
|
|
|
Description
|
|
|
|
</title>
|
|
|
|
|
|
|
|
<para>
|
|
|
|
<application>postmaster</application>
|
|
|
|
manages the communication between frontend and backend processes, as
|
|
|
|
well as allocating the shared buffer pool and SysV semaphores
|
|
|
|
(on machines without a test-and-set instruction).
|
|
|
|
<application>postmaster</application>
|
|
|
|
does not itself interact with the user and should be started as a
|
|
|
|
background process.
|
|
|
|
</para>
|
|
|
|
|
|
|
|
<para>
|
|
|
|
<emphasis>Only one postmaster should be running at a time in a given
|
|
|
|
<productname>Postgres</productname> installation.</emphasis>
|
|
|
|
Here, an installation means a database directory and
|
|
|
|
<application>postmaster</application> port number.
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|
You can run more than one postmaster on a machine only if each one has a
|
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|
separate directory and port number.
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</para>
|
1999-05-27 17:49:15 +02:00
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</refsect1>
|
1999-05-26 19:25:38 +02:00
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|
1999-05-27 17:49:15 +02:00
|
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|
<refsect1 id="R1-APP-POSTMASTER-2">
|
1999-05-26 19:25:38 +02:00
|
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|
<refsect1info>
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|
|
<date>1998-10-04</date>
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|
</refsect1info>
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|
|
|
<title>
|
|
|
|
Notes
|
|
|
|
</title>
|
|
|
|
|
|
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|
<para>
|
|
|
|
If at all possible,
|
|
|
|
<emphasis>do not</emphasis>
|
|
|
|
use <literal>SIGKILL</literal>
|
|
|
|
when killing the <application>postmaster</application>.
|
|
|
|
<literal>SIGHUP</literal>,
|
|
|
|
<literal>SIGINT</literal>,
|
|
|
|
or
|
|
|
|
<literal>SIGTERM</literal>
|
|
|
|
(the default signal for
|
|
|
|
<application>kill</application>(1))"
|
|
|
|
should be used instead. Using
|
|
|
|
|
|
|
|
<programlisting>
|
|
|
|
% kill -KILL
|
|
|
|
</programlisting>
|
|
|
|
|
|
|
|
or its alternative form
|
|
|
|
|
|
|
|
<programlisting>
|
|
|
|
% kill -9
|
|
|
|
</programlisting>
|
|
|
|
|
|
|
|
will prevent <application>postmaster</application>
|
|
|
|
from freeing the system resources (e.g., shared memory and semaphores)
|
|
|
|
that it holds before dying. This prevents you from having to deal with
|
|
|
|
the problem with shared memory described earlier.
|
|
|
|
</para>
|
|
|
|
|
|
|
|
<para>
|
|
|
|
Useful utilities for dealing with shared memory problems include
|
|
|
|
<application>ipcs(1)</application>,
|
|
|
|
<application>ipcrm(1</application>), and
|
|
|
|
<application>ipcclean(1)</application>.
|
|
|
|
</para>
|
|
|
|
</refsect1>
|
|
|
|
|
1999-05-27 17:49:15 +02:00
|
|
|
<refsect1 id="R1-APP-POSTMASTER-3">
|
1999-05-26 19:25:38 +02:00
|
|
|
<refsect1info>
|
|
|
|
<date>1998-10-04</date>
|
|
|
|
</refsect1info>
|
|
|
|
<title>
|
|
|
|
Usage
|
|
|
|
</title>
|
|
|
|
<para>
|
|
|
|
To start <application>postmaster</application> using default
|
|
|
|
values, type:
|
|
|
|
|
|
|
|
<programlisting>
|
|
|
|
% nohup postmaster >logfile 2>&1 &
|
|
|
|
</programlisting>
|
|
|
|
|
|
|
|
This command will start up <application>postmaster</application>
|
|
|
|
on the default port (5432). This is the
|
|
|
|
simplest and most common way to start the
|
|
|
|
<application>postmaster</application>.
|
|
|
|
</para>
|
|
|
|
|
|
|
|
<para>
|
|
|
|
To start <application>postmaster</application> with a specific port
|
|
|
|
and executable name:
|
|
|
|
|
|
|
|
<programlisting>
|
|
|
|
% nohup postmaster -p 1234 &
|
|
|
|
</programlisting>
|
|
|
|
|
|
|
|
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
|
|
|
|
|
|
|
|
<programlisting>
|
|
|
|
% psql -p 1234
|
|
|
|
</programlisting>
|
|
|
|
|
|
|
|
or set the environment variable <envar>PGPORT</envar>:
|
|
|
|
|
|
|
|
<programlisting>
|
|
|
|
% setenv PGPORT 1234
|
|
|
|
% psql
|
|
|
|
</programlisting>.
|
1999-05-27 17:49:15 +02:00
|
|
|
</para>
|
1999-05-26 19:25:38 +02:00
|
|
|
</refsect1>
|
|
|
|
</refentry>
|
|
|
|
|
|
|
|
<!-- Keep this comment at the end of the file
|
|
|
|
Local variables:
|
|
|
|
mode: sgml
|
|
|
|
sgml-omittag:nil
|
|
|
|
sgml-shorttag:t
|
|
|
|
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
|
|
|
|
End:
|
|
|
|
-->
|