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.\" This is -*-nroff-*-
.\" XXX standard disclaimer belongs here....
.\" $Header: /cvsroot/pgsql/doc/src/sgml/ref/postgres-ref.sgml,v 1.1 1999/05/26 17:25:38 thomas Exp $
.TH POSTGRESQL UNIX 05/19/99 PostgreSQL PostgreSQL
.SH NAME
postgres - the Postgres backend server
.SH SYNOPSIS
.BR "postgres"
[\c
.BR "-B"
n_buffers]
[\c
.BR "-C"
]
[\c
.BR "-D"
data_directory]
[\c
.BR "-E"
]
[\c
.BR "-F"
]
[\c
.BR "-O"
]
[\c
.BR "-Q"
]
[\c
.BR "-S kbytes"
]
[\c
.BR "-d"
debug_level]
[\c
.BR "-e"
]
[\c
.BR "-o"
output_file]
[\c
.BR "-s"
]
[\c
.BR "-v protocol"
]
[dbname]
.in -5n
.SH DESCRIPTION
The Postgres backend server can be executed directly from the user shell.
This should be done only while debugging by the DBA, and should not be
done while other Postgres backends are being managed by a
.IR postmaster
on this set of databases.
.PP
Some of the switches explained in this man page can be passed to the backend
through the "database options" field of a connection request, and thus can be
set for a particular backend without going to the trouble of restarting the
postmaster. This is particularly handy for debugging-related switches.
.PP
The optional argument
.IR dbname
specifies the name of the database to be accessed.
.IR Dbname
defaults to the value of the
.SM USER
environment variable.
.PP
The
.IR postgres
server understands the following command-line options:
.TP
.BR "-B" " n_buffers"
If the backend is running under the
.IR postmaster ,
.IR "n_buffers"
is the number of shared-memory buffers that the
.IR "postmaster"
has allocated for the backend server processes that it starts. If the
backend is running standalone, this specifies the number of buffers to
allocate. This value defaults to 64 buffers, where each buffer is 8k bytes
(or whatever BLCKSZ is set to in config.h).
.TP
.BR "-C"
Do not show server version number.
.TP
.BR "-D" " data_directory"
This option specifies the pathname of the directory that contains the
database system data (the tables, the catalogs, etc.). If you don't
specify this option, Postgres uses the value of the PGDATA environment
variable. You must either specify a -D option or set PGDATA.
The data directory pathname for a database system is normally determined when
the database system is created with
.IR initdb ,
with a --pgdata option to
.IR initdb .
.TP
.BR "-E"
Echo all queries.
.TP
.BR "-F"
Disable automatic fsync() call after each transaction.
This option improves performance, but an operating system crash
while a transaction is in progress will probably cause data loss.
.TP
.BR "-O"
Override restrictions, so system table structures can be modified(pg_*).
.TP
.BR "-Q"
Specifies \*(lqquiet\*(rq mode.
.TP
.BR "-S" " kbytes"
Specifies the amount of memory to be used by internal sorts and hashes
before resorting to temporary disk files. The value is specified in
kilobytes, and defaults to 512 kilobytes. Note that for a complex query,
several sorts and/or hashes might be running in parallel, and each one
will be allowed to use as much as -S kilobytes before it starts to put
data into temporary files.
.TP
.BR "-e"
The
.IR "-e"
option controls how dates are input to and output from the database.
.IP
If the
.IR "-e"
option is supplied, then all dates passed to and from the frontend
processes will be assumed to be in
.IR "European"
format ie.
.IR "DD-MM-YYYY"
otherwise dates are input and output in
.IR "American"
format ie.
.IR "MM-DD-YYYY"
.TP
.BR "-d" " debug_level"
Turns on debugging at the numeric level
.IR "debug_level" .
Turning on debugging will cause query, parse trees, and query plans to
be displayed.
.TP
.BR "-o" " output_file"
Sends all debugging and error output to
.IR output_file .
If the backend is running under the
.IR postmaster ,
error messages are still sent to the frontend process as well as to
.IR output_file ,
but debugging output is sent to the controlling tty of the
.IR postmaster
(since only one file descriptor can be sent to an actual file).
.TP
.BR "-s"
Print time information and other statistics at the end of each query.
This is useful for benchmarking or for use in tuning the number of
buffers.
.TP
.BR "-v" " protocol"
Specifies the number of the frontend/backend protocol to be used for this
particular session.
.SH "DEVELOPER COMMAND OPTIONS"
There are several other options that may be specified, used mainly
for debugging purposes. These are listed here only for the use by
Postgres system developers.
.BR "Use of any of these options is highly discouraged" .
Furthermore, any of these options may disappear or change at any time.
.TP
.BR "-A" "n|r|b|Q\fIn\fP|X\fIn\fP"
.IP
This option generates a tremendous amount of output.
.TP
.BR "-L"
Turns off the locking system.
.TP
.BR "-N"
Disables use of newline as a query delimiter.
.TP
.BR "-f"
Forbids the use of particular scan and join methods:
.IR s " and " i
disable sequential and index scans respectively, while
.IR n ", " m " and " h
disable nested-loop, merge and hash joins respectively.
(Neither sequential scans nor nested-loop joins can be disabled completely;
the -fs and -fn options simply discourage the optimizer from using those
plan types if it has any other alternative.)
.TP
.BR "-i"
Prevents query execution, but shows the plan tree.
.TP
.BR "-p" " databasename"
Indicates to the backend server that it has been started by a
.IR postmaster
and make different assumptions about buffer pool management, file
descriptors, etc. Switches following -p are restricted to those
considered "secure".
.TP
.BR "-t" "pa[rser]|pl[anner]|e[xecutor]"
Print timing statistics for each query relating to each of the major
system modules. This option cannot be used with
.BR "-s" .
.SH "SEE ALSO"
ipcclean(1),
psql(1),
postmaster(1).
.SH "DIAGNOSTICS"
Of the nigh-infinite number of error messages you may see when you
execute the backend server directly, the most common will probably be:
.TP
.BR "semget: No space left on device"
If you see this message, you should run the
.IR ipcclean
command. After doing this, try starting
.IR postgres
again. If this still doesn't work, you probably need to configure
your kernel for shared memory and semaphores as described in the
installation notes.
doc/src/sgml/ref/postmaster.sgml 0 → 100644
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<refentry id="APP-POSTMASTER">
<refmeta>
<refentrytitle>
<application>postmaster</application>
</refentrytitle>
<refmiscinfo>Application</refmiscinfo>
</refmeta>
<refnamediv>
<refname id="postmaster">
<application>postmaster</application>
</refname>
<refpurpose>
Run the <productname>Postgres</productname> multi-user backend
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<refsynopsisdivinfo>
<date>1999-05-19</date>
</refsynopsisdivinfo>
<synopsis>
postmaster [ -B <replaceable class="parameter">nBuffers</replaceable> ]
[ -D <replaceable class="parameter">DataDir</replaceable> ] [-N <replaceable class="parameter">nBackends</replaceable> ] [ -S ]
[ -d [ <replaceable class="parameter">DebugLevel</replaceable> ] ]
[ -i ] [ -o <replaceable class="parameter">BackendOptions</replaceable> ] [ -p <replaceable class="parameter">port</replaceable> ]
postmaster [ -n | -s ] ...
</synopsis>
<refsect2 id="R2-APP-POSTMASTER-1">
<refsect2info>
<date>1999-05-19</date>
</refsect2info>
<title>
Inputs
</title>
<para>
<application>postmaster</application> accepts the following command line arguments:
<variablelist>
<varlistentry>
<term>
-B <replaceable class="parameter">nBuffers</replaceable>
</term>
<listitem>
<para>
The number of shared-memory buffers for the
<application>postmaster</application>
to allocate and manage for the backend server processes that it
starts. This value defaults to 64 buffers, where each buffer is 8k bytes
(or whatever BLCKSZ is set to in config.h).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
-D <replaceable class="parameter">DataDir</replaceable>
</term>
<listitem>
<para>
Specifies the directory to use as the root of the tree of database
directories. If -D is not given, the default data directory name is
the value of the environment variable
<envar>PGDATA</envar>.
If <envar>PGDATA</envar> is not set, then the directory used is
<filename>$POSTGRESHOME/data</filename>.
If neither environment variable is set and this command-line
option is not specified, the default directory that was
set at compile-time is used.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
-N <replaceable class="parameter">nBackends</replaceable>
</term>
<listitem>
<para>
The maximum number of backend server processes that this postmaster
is allowed to start. In the default configuration, this value
is usually set
to 32, and can be set as high as 1024 if your system will support that
many processes. Both the default and upper limit values can be altered
when building <productname>Postgres</productname> (see src/include/config.h).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
-S
</term>
<listitem>
<para>
Specifies that the <application>postmaster</application>
process should start up in silent mode. That is, it will disassociate
from the user's (controlling) tty and start its own process group.
This should not be used in combination with debugging options because
any messages printed to standard output and standard error are
discarded.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
-d [ <replaceable class="parameter">DebugLevel</replaceable> ]
</term>
<listitem>
<para>
The optional argument <replaceable class="parameter">DebugLevel</replaceable>
determines the amount of debugging output the backend servers will
produce.
If <replaceable class="parameter">DebugLevel</replaceable>
is one, the postmaster will trace all connection traffic,
and nothing else.
For levels two and higher,
debugging is turned on in the backend process and the postmaster
displays more information,
including the backend environment and process traffic.
Note that if no file is specified for backend servers to
send their debugging output then this output will appear on the
controlling tty of their parent <application>postmaster</application>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
-i
</term>
<listitem>
<para>
This enables TCP/IP or Internet domain socket communication.
Without this option, only local Unix domain socket communication is
possible.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
-o <replaceable class="parameter">BackendOptions</replaceable>
</term>
<listitem>
<para>
The
<literal>postgres</literal>
options specified in
<replaceable class="parameter">BackendOptions</replaceable>
are passed to all backend server processes started by this
<application>postmaster</application>.
If the option string contains any spaces, the entire string must be
quoted.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
-p <replaceable class="parameter">port</replaceable>
</term>
<listitem>
<para>
Specifies the TCP/IP port or local Unix domain socket file extension
on which the <application>postmaster</application>
is to listen for connections from frontend 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 when Postgres was
compiled (normally 5432). If you specify a port other than the
default port then all frontend applications (including
<application>psql</application>) must specify the same
port using either command-line options or
<envar>PGPORT</envar>.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
<para>
A few command line options are available for debugging in the case
when a backend dies abnormally.
These options control the behavior of the
<application>postmaster</application> in this situation, and
<emphasis>neither option is intended for use in
ordinary operation</emphasis>.
</para>
<para>
The ordinary strategy for this situation is to notify all other
backends that they must terminate and then reinitialize the shared
memory and semaphores. This is because an errant backend could have
corrupted some shared state before terminating.
</para>
<para>
These special-case options are:
<variablelist>
<varlistentry>
<term>
-n
</term>
<listitem>
<para>
If the <literal>-n</literal>
option is supplied, then the
<application>postmaster</application>
does not reinitialize shared data structures. A knowledgable system
programmer can then use the
<application>shmemdoc</application>
program to examine shared memory and semaphore state.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
-s
</term>
<listitem>
<para>
<application>postmaster</application>
will stop all other backend processes by sending the signal
<literal>SIGSTOP</literal>,
but will not cause them to terminate. This permits system programmers
to collect core dumps from all backend processes by hand.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect2>
<refsect2 id="R2-APP-POSTMASTER-1">
<refsect2info>
<date>1999-05-19</date>
</refsect2info>
<title>
Outputs
</title>
<para>
<variablelist>
<!--
<varlistentry>
<term>
FindBackend: could not find a backend to execute...
</term>
<listitem>
<para>
If you see this message, you do not have the
<application>postgres</application>
executable in your path. Add the directory in which
<application>postgres</application> resides to
your path.
</para>
</listitem>
</varlistentry>
-->
<varlistentry>
<term>
semget: No space left on device
</term>
<listitem>
<para>
If you see this message, you should run the
<application>ipcclean</application>
command. After doing this, try starting
<application>postmaster</application>
again. If this still doesn't work, you probably need to configure
your kernel for shared memory and semaphores as described in the
installation notes. If you run multiple instances of
<application>postmaster</application>
on a single host, or have a kernel with particularly small shared memory
and/or semaphore limits, you may have to reconfigure your kernel to increase
its shared memory or semaphore parameters.
<tip>
<para>
You may be able to postpone
reconfiguring your kernel by decreasing -B to reduce
<productname>Postgres</productname>' shared memory
consumption, or by reducing -N to reduce Postgres' semaphore
consumption.
</para>
</tip>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
StreamServerPort: cannot bind to port
</term>
<listitem>
<para>
If you see this message, you should be certain that there is no other
<application>postmaster</application>
process already running. The easiest way to determine this is by
using the command
<programlisting>
% ps -ax | grep postmaster
</programlisting>
on BSD-based systems, or
<programlisting>
% ps -e | grep postmast
</programlisting>
for System V-like or POSIX-compliant systems such as HP-UX.
</para>
<para>
If you
are sure that no other
<application>postmaster</application>
processes are running and you still get this error, try specifying a
different port using the
<literal>-p</literal>
option. You may also get this error if you terminate the
<application>postmaster</application>
and immediately restart it using the same port; in this case, you must
simply wait a few seconds until the operating system closes the port
before trying again. Finally, you may get this error if you specify
a port number that your operating system considers to be reserved.
For example, many versions of Unix consider port numbers under 1024 to
be <firstterm>trusted</firstterm>
and only permit the Unix superuser to access them.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
IpcMemoryAttach: shmat() failed: Permission denied
</term>
<listitem>
<para>
A likely explanation is that another user attempted to start a
<application>postmaster</application>
process on the same port which acquired shared resources and then
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
a single host. If there are no other
<application>postmaster</application>
processes currently running (see above), run
<application>ipcclean</application>
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.
You can run more than one postmaster on a machine only if each one has a
separate directory and port number.
</para>
<refsect1 id="R1-APP-VACUUMDB-2">
<refsect1info>
<date>1998-10-04</date>
</refsect1info>
<title>
Notes
</title>
<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>
<refsect1 id="R1-APP-VACUUMDB-3">
<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>.
</refsect1>
</refentry>
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sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
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sgml-local-ecat-files:nil
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