a2822fb933
When a btree index contains all columns required by the query, and the visibility map shows that all tuples on a target heap page are visible-to-all, we don't need to fetch that heap page. This patch depends on the previous patches that made the visibility map reliable. There's a fair amount left to do here, notably trying to figure out a less chintzy way of estimating the cost of an index-only scan, but the core functionality seems ready to commit. Robert Haas and Ibrar Ahmed, with some previous work by Heikki Linnakangas.
826 lines
29 KiB
Plaintext
826 lines
29 KiB
Plaintext
<!--
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doc/src/sgml/ref/postgres-ref.sgml
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PostgreSQL documentation
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-->
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<refentry id="app-postgres">
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<refmeta>
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<refentrytitle><application>postgres</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>postgres</refname>
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<refpurpose><productname>PostgreSQL</productname> database server</refpurpose>
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</refnamediv>
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<indexterm zone="app-postgres">
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<primary>postgres</primary>
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</indexterm>
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<refsynopsisdiv>
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<cmdsynopsis>
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<command>postgres</command>
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<arg rep="repeat"><replaceable>option</></arg>
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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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|
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<para>
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<command>postgres</command> is the
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<productname>PostgreSQL</productname> database server. In order
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for a client application to access a database it connects (over a
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network or locally) to a running <command>postgres</command> instance.
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The <command>postgres</command> instance then starts a separate server
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process to handle the connection.
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</para>
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<para>
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One <command>postgres</command> instance always manages the data of
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exactly one database cluster. A database cluster is a collection
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of databases that is stored at a common file system location (the
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<quote>data area</quote>). More than one
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<command>postgres</command> instance can run on a system at one
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time, so long as they use different data areas and different
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communication ports (see below). When
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<command>postgres</command> starts it needs to know the location
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of the data area. The location must be specified by the
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<option>-D</option> option or the <envar>PGDATA</envar> environment
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|
variable; there is no default. Typically, <option>-D</option> or
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<envar>PGDATA</envar> points directly to the data area directory
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created by <xref linkend="app-initdb">. Other possible file layouts are
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discussed in <xref linkend="runtime-config-file-locations">.
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</para>
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|
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|
<para>
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By default <command>postgres</command> starts in the
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foreground and prints log messages to the standard error stream. In
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practical applications <command>postgres</command>
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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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The <command>postgres</command> command can also be called in
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single-user mode. The primary use for this mode is during
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bootstrapping by <xref linkend="app-initdb">. Sometimes it is used
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for debugging or disaster recovery; note that running a single-user
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|
server is not truly suitable for debugging the server, since no
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realistic interprocess communication and locking will happen.
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|
When invoked in single-user
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|
mode from the shell, the user can enter queries and the results
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will be printed to the screen, but in a form that is more useful
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|
for developers than end users. In the single-user mode,
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|
the session user will be set to the user with ID 1, and implicit
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|
superuser powers are granted to this user.
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|
This user does not actually have to exist, so the single-user mode
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can be used to manually recover from certain
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|
kinds of accidental damage to the system catalogs.
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|
</para>
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</refsect1>
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|
|
|
<refsect1 id="app-postgres-options">
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|
<title>Options</title>
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|
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|
<para>
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<command>postgres</command> accepts the following command-line
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arguments. For a detailed discussion of the options consult <xref
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linkend="runtime-config">. You can save typing most of these
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|
options by setting up a configuration file. Some (safe) options
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|
can also be set from the connecting client in an
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|
application-dependent way to apply only for that session. For
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|
example, if the environment variable <envar>PGOPTIONS</envar> is
|
|
set, then <application>libpq</>-based clients will pass that
|
|
string to the server, which will interpret it as
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|
<command>postgres</command> command-line options.
|
|
</para>
|
|
|
|
<refsect2>
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|
<title>General Purpose</title>
|
|
|
|
<variablelist>
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|
<varlistentry>
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|
<term><option>-A 0|1</option></term>
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<listitem>
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<para>
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Enables run-time assertion checks, which is a debugging aid to
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|
detect programming mistakes. This option is only available if
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|
assertions were enabled when <productname>PostgreSQL</> was
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|
compiled. If so, the default is on.
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|
</para>
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|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
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|
<term><option>-B <replaceable class="parameter">nbuffers</replaceable></option></term>
|
|
<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. The default value of this parameter is chosen
|
|
automatically by <application>initdb</application>.
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|
Specifying this option is equivalent to setting the
|
|
<xref linkend="guc-shared-buffers"> configuration parameter.
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|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
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|
<term><option>-c <replaceable>name</replaceable>=<replaceable>value</replaceable></option></term>
|
|
<listitem>
|
|
<para>
|
|
Sets a named run-time parameter. The configuration parameters
|
|
supported by <productname>PostgreSQL</productname> are
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|
described in <xref linkend="runtime-config">. Most of the
|
|
other command line options are in fact short forms of such a
|
|
parameter assignment. <option>-c</> can appear multiple times
|
|
to set multiple parameters.
|
|
</para>
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|
</listitem>
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|
</varlistentry>
|
|
|
|
<varlistentry>
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|
<term><option>-C <replaceable>name</replaceable></option></term>
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|
<listitem>
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|
<para>
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|
Returns the value of a named run-time parameter, and exits.
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|
(See the <option>-c</> option above for details.) This can
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|
be used on a running server, and returns values from
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|
<filename>postgresql.conf</>, modified by any parameters
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|
supplied in this invocation. It does not reflect parameters
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|
supplied when the cluster was started.
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|
</para>
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|
</listitem>
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|
</varlistentry>
|
|
|
|
<varlistentry>
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|
<term><option>-d <replaceable>debug-level</replaceable></option></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
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|
from 1 to 5. It is also possible to pass <literal>-d
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|
0</literal> for a specific session, which will prevent the
|
|
server log level of the parent <command>postgres</> process from being
|
|
propagated to this session.
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|
</para>
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|
</listitem>
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|
</varlistentry>
|
|
|
|
<varlistentry>
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|
<term><option>-D <replaceable class="parameter">datadir</replaceable></option></term>
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<listitem>
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<para>
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|
Specifies the file system location of the data directory or
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|
configuration file(s). See
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|
<xref linkend="runtime-config-file-locations"> for details.
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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><option>-e</option></term>
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<listitem>
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<para>
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|
Sets the default date style to <quote>European</quote>, that is
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<literal>DMY</> ordering of input date fields. This also causes
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|
the day to be printed before the month in certain date output formats.
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See <xref linkend="datatype-datetime"> for more information.
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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><option>-F</option></term>
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<listitem>
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<para>
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|
Disables <function>fsync</function> calls for improved
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|
performance, at the risk of data corruption in the event of a
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|
system crash. Specifying this option is equivalent to
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|
disabling the <xref linkend="guc-fsync"> configuration
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|
parameter. Read the detailed documentation before using this!
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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><option>-h <replaceable class="parameter">hostname</replaceable></option></term>
|
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<listitem>
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|
<para>
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|
Specifies the IP host name or address on which
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|
<command>postgres</command> is to listen for TCP/IP
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|
connections from client applications. The value can also be a
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|
comma-separated list of addresses, or <literal>*</> to specify
|
|
listening on all available interfaces. An empty value
|
|
specifies not listening on any IP addresses, in which case
|
|
only Unix-domain sockets can be used to connect to the
|
|
server. Defaults to listening only on
|
|
<systemitem class="systemname">localhost</systemitem>.
|
|
Specifying this option is equivalent to setting the <xref
|
|
linkend="guc-listen-addresses"> configuration parameter.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>-i</option></term>
|
|
<listitem>
|
|
<para>
|
|
Allows remote clients to connect via TCP/IP (Internet domain)
|
|
connections. Without this option, only local connections are
|
|
accepted. This option is equivalent to setting
|
|
<varname>listen_addresses</> to <literal>*</> in
|
|
<filename>postgresql.conf</> or via <option>-h</>.
|
|
</para>
|
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<para>
|
|
This option is deprecated since it does not allow access to the
|
|
full functionality of <xref linkend="guc-listen-addresses">.
|
|
It's usually better to set <varname>listen_addresses</> directly.
|
|
</para>
|
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</listitem>
|
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</varlistentry>
|
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|
|
<varlistentry>
|
|
<term><option>-k <replaceable class="parameter">directory</replaceable></option></term>
|
|
<listitem>
|
|
<para>
|
|
Specifies the directory of the Unix-domain socket on which
|
|
<command>postgres</command> is to listen for
|
|
connections from client applications. The default is normally
|
|
<filename>/tmp</filename>, but can be changed at build time.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>-l</option></term>
|
|
<listitem>
|
|
<para>
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|
Enables secure connections using <acronym>SSL</acronym>.
|
|
<productname>PostgreSQL</productname> must have been compiled with
|
|
support for <acronym>SSL</acronym> for this option to be
|
|
available. For more information on using <acronym>SSL</acronym>,
|
|
refer to <xref linkend="ssl-tcp">.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>-N <replaceable class="parameter">max-connections</replaceable></option></term>
|
|
<listitem>
|
|
<para>
|
|
Sets the maximum number of client connections that this
|
|
server will accept. The default value of this parameter is chosen
|
|
automatically by <application>initdb</application>.
|
|
Specifying this option is equivalent to setting the
|
|
<xref linkend="guc-max-connections"> configuration parameter.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>-o <replaceable class="parameter">extra-options</replaceable></option></term>
|
|
<listitem>
|
|
<para>
|
|
The command-line-style options specified in <replaceable
|
|
class="parameter">extra-options</replaceable> are passed to
|
|
all server processes started by this
|
|
<command>postgres</command> process. If the option string contains
|
|
any spaces, the entire string must be quoted.
|
|
</para>
|
|
|
|
<para>
|
|
The use of this option is obsolete; all command-line options
|
|
for server processes can be specified directly on the
|
|
<command>postgres</command> command line.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>-p <replaceable class="parameter">port</replaceable></option></term>
|
|
<listitem>
|
|
<para>
|
|
Specifies the TCP/IP port or local Unix domain socket file
|
|
extension on which <command>postgres</command>
|
|
is to listen for connections from client applications.
|
|
Defaults to the value of the <envar>PGPORT</envar> environment
|
|
variable, or if <envar>PGPORT</envar> is not set, then
|
|
defaults to the value established during compilation (normally
|
|
5432). If you specify a port other than the default port,
|
|
then all client applications must specify the same port using
|
|
either command-line options or <envar>PGPORT</envar>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>-s</option></term>
|
|
<listitem>
|
|
<para>
|
|
Print time information and other statistics at the end of each command.
|
|
This is useful for benchmarking or for use in tuning the number of
|
|
buffers.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>-S</option> <replaceable class="parameter">work-mem</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
Specifies the amount of memory to be used by internal sorts and hashes
|
|
before resorting to temporary disk files. See the description of the
|
|
<varname>work_mem</> configuration parameter in <xref
|
|
linkend="runtime-config-resource-memory">.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>--<replaceable>name</replaceable>=<replaceable>value</replaceable></option></term>
|
|
<listitem>
|
|
<para>
|
|
Sets a named run-time parameter; a shorter form of
|
|
<option>-c</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>--describe-config</option></term>
|
|
<listitem>
|
|
<para>
|
|
This option dumps out the server's internal configuration variables,
|
|
descriptions, and defaults in tab-delimited <command>COPY</> format.
|
|
It is designed primarily for use by administration tools.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect2>
|
|
|
|
<refsect2>
|
|
<title>Semi-internal Options</title>
|
|
|
|
<para>
|
|
The options described here are used
|
|
mainly for debugging purposes, and in some cases to assist with
|
|
recovery of severely damaged databases. There should be no reason
|
|
to use them in a production database setup. They are listed
|
|
here only for use by <productname>PostgreSQL</productname>
|
|
system developers. Furthermore, these options might
|
|
change or be removed in a future release without notice.
|
|
</para>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><option>-f</option> <literal>{ s | i | o | b | t | n | m | h }</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Forbids the use of particular scan and join methods:
|
|
<literal>s</literal> and <literal>i</literal>
|
|
disable sequential and index scans respectively,
|
|
<literal>o</literal>, <literal>b</literal> and <literal>t</literal>
|
|
disable index-only scans, bitmap index scans, and TID scans
|
|
respectively, while
|
|
<literal>n</literal>, <literal>m</literal>, and <literal>h</literal>
|
|
disable nested-loop, merge and hash joins respectively.
|
|
</para>
|
|
|
|
<para>
|
|
Neither sequential scans nor nested-loop joins can be disabled
|
|
completely; the <literal>-fs</literal> and
|
|
<literal>-fn</literal> options simply discourage the optimizer
|
|
from using those plan types if it has any other alternative.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>-n</option></term>
|
|
<listitem>
|
|
<para>
|
|
This option is for debugging problems that cause a server
|
|
process to die abnormally. The ordinary strategy in this
|
|
situation is to notify all other server processes that they
|
|
must terminate and then reinitialize the shared memory and
|
|
semaphores. This is because an errant server process could
|
|
have corrupted some shared state before terminating. This
|
|
option specifies that <command>postgres</command> will
|
|
not reinitialize shared data structures. A knowledgeable
|
|
system programmer can then use a debugger to examine shared
|
|
memory and semaphore state.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>-O</option></term>
|
|
<listitem>
|
|
<para>
|
|
Allows the structure of system tables to be modified. This is
|
|
used by <command>initdb</command>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>-P</option></term>
|
|
<listitem>
|
|
<para>
|
|
Ignore system indexes when reading system tables, but still update
|
|
the indexes when modifying the tables. This is useful when
|
|
recovering from damaged system indexes.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>-t</option> <literal>pa[rser] | pl[anner] | e[xecutor]</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Print timing statistics for each query relating to each of the
|
|
major system modules. This option cannot be used together
|
|
with the <option>-s</option> option.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>-T</option></term>
|
|
<listitem>
|
|
<para>
|
|
This option is for debugging problems that cause a server
|
|
process to die abnormally. The ordinary strategy in this
|
|
situation is to notify all other server processes that they
|
|
must terminate and then reinitialize the shared memory and
|
|
semaphores. This is because an errant server process could
|
|
have corrupted some shared state before terminating. This
|
|
option specifies that <command>postgres</command> will
|
|
stop all other server 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 server processes by hand.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>-v</option> <replaceable class="parameter">protocol</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
Specifies the version number of the frontend/backend protocol
|
|
to be used for a particular session. This option is for
|
|
internal use only.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>-W</option> <replaceable class="parameter">seconds</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
A delay of this many seconds occurs when a new server process
|
|
is started, after it conducts the authentication procedure.
|
|
This is intended to give an opportunity to attach to the
|
|
server process with a debugger.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect2>
|
|
|
|
<refsect2>
|
|
<title>Options for Single-User Mode</title>
|
|
|
|
<para>
|
|
The following options only apply to the single-user mode.
|
|
</para>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><option>--single</option></term>
|
|
<listitem>
|
|
<para>
|
|
Selects the single-user mode. This must be the first argument
|
|
on the command line.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><replaceable class="parameter">database</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
Specifies the name of the database to be accessed. This must be
|
|
the last argument on the command line. If it is
|
|
omitted it defaults to the user name.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>-E</option></term>
|
|
<listitem>
|
|
<para>
|
|
Echo all commands.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>-j</option></term>
|
|
<listitem>
|
|
<para>
|
|
Disables use of newline as a statement delimiter.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><option>-r</option> <replaceable class="parameter">filename</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
Send all server log output to <replaceable
|
|
class="parameter">filename</replaceable>. In normal multiuser
|
|
mode, this option is ignored, and <systemitem>stderr</> is
|
|
used by all processes.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect2>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Environment</title>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><envar>PGCLIENTENCODING</envar></term>
|
|
|
|
<listitem>
|
|
<para>
|
|
Default character encoding used by clients. (The clients can
|
|
override this individually.) This value can also be set in the
|
|
configuration file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><envar>PGDATA</envar></term>
|
|
|
|
<listitem>
|
|
<para>
|
|
Default data directory location
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><envar>PGDATESTYLE</envar></term>
|
|
|
|
<listitem>
|
|
<para>
|
|
Default value of the <xref linkend="guc-datestyle"> run-time
|
|
parameter. (The use of this environment variable is deprecated.)
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><envar>PGPORT</envar></term>
|
|
|
|
<listitem>
|
|
<para>
|
|
Default port number (preferably set in the configuration file)
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><envar>TZ</envar></term>
|
|
|
|
<listitem>
|
|
<para>
|
|
Server time zone
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Diagnostics</title>
|
|
|
|
<para>
|
|
A failure message mentioning <literal>semget</> or
|
|
<literal>shmget</> probably indicates you need to configure your
|
|
kernel to provide adequate shared memory and semaphores. For more
|
|
discussion see <xref linkend="kernel-resources">. You might be able
|
|
to postpone reconfiguring your kernel by decreasing <xref
|
|
linkend="guc-shared-buffers"> to reduce the shared memory
|
|
consumption of <productname>PostgreSQL</>, and/or by reducing
|
|
<xref linkend="guc-max-connections"> to reduce the semaphore
|
|
consumption.
|
|
</para>
|
|
|
|
<para>
|
|
A failure message suggesting that another server is already running
|
|
should be checked carefully, for example by using the command
|
|
<screen>
|
|
<prompt>$</prompt> <userinput>ps ax | grep postgres</userinput>
|
|
</screen>
|
|
or
|
|
<screen>
|
|
<prompt>$</prompt> <userinput>ps -ef | grep postgres</userinput>
|
|
</screen>
|
|
depending on your system. If you are certain that no conflicting
|
|
server is running, you can remove the lock file mentioned in the
|
|
message and try again.
|
|
</para>
|
|
|
|
<para>
|
|
A failure message indicating inability to bind to a port might
|
|
indicate that that port is already in use by some
|
|
non-<productname>PostgreSQL</productname> process. You might also
|
|
get this error if you terminate <command>postgres</command>
|
|
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 might 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 <quote>trusted</quote> and only permit
|
|
the Unix superuser to access them.
|
|
</para>
|
|
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Notes</title>
|
|
|
|
<para>
|
|
The utility command <xref linkend="app-pg-ctl"> can be used to
|
|
start and shut down the <command>postgres</command> server
|
|
safely and comfortably.
|
|
</para>
|
|
|
|
<para>
|
|
If at all possible, <emphasis>do not</emphasis> use
|
|
<literal>SIGKILL</literal> to kill the main
|
|
<command>postgres</command> server. Doing so will prevent
|
|
<command>postgres</command> from freeing the system
|
|
resources (e.g., shared memory and semaphores) that it holds before
|
|
terminating. This might cause problems for starting a fresh
|
|
<command>postgres</command> run.
|
|
</para>
|
|
|
|
<para>
|
|
To terminate the <command>postgres</command> server normally, the
|
|
signals <literal>SIGTERM</literal>, <literal>SIGINT</literal>, or
|
|
<literal>SIGQUIT</literal> can be used. The first will wait for
|
|
all clients to terminate before quitting, the second will
|
|
forcefully disconnect all clients, and the third will quit
|
|
immediately without proper shutdown, resulting in a recovery run
|
|
during restart.
|
|
</para>
|
|
|
|
<para>
|
|
The <literal>SIGHUP</literal> signal will reload
|
|
the server configuration files. It is also possible to send
|
|
<literal>SIGHUP</literal> to an individual server process, but that
|
|
is usually not sensible.
|
|
</para>
|
|
|
|
<para>
|
|
To cancel a running query, send the <literal>SIGINT</literal> signal
|
|
to the process running that command.
|
|
</para>
|
|
|
|
<para>
|
|
The <command>postgres</command> server uses <literal>SIGTERM</literal>
|
|
to tell subordinate server processes to quit normally and
|
|
<literal>SIGQUIT</literal> to terminate without the normal cleanup.
|
|
These signals <emphasis>should not</emphasis> be used by users. It
|
|
is also unwise to send <literal>SIGKILL</literal> to a server
|
|
process — the main <command>postgres</command> process will
|
|
interpret this as a crash and will force all the sibling processes
|
|
to quit as part of its standard crash-recovery procedure.
|
|
</para>
|
|
</refsect1>
|
|
|
|
<refsect1 id="app-postgres-bugs">
|
|
<title>Bugs</title>
|
|
<para>
|
|
The <option>--</> options will not work on <systemitem
|
|
class="osname">FreeBSD</> or <systemitem class="osname">OpenBSD</>.
|
|
Use <option>-c</> instead. This is a bug in the affected operating
|
|
systems; a future release of <productname>PostgreSQL</productname>
|
|
will provide a workaround if this is not fixed.
|
|
</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Usage</title>
|
|
|
|
<para>
|
|
To start a single-user mode server, use a command like
|
|
<screen>
|
|
<userinput>postgres --single -D /usr/local/pgsql/data <replaceable>other-options</> my_database</userinput>
|
|
</screen>
|
|
Provide the correct path to the database directory with <option>-D</>, or
|
|
make sure that the environment variable <envar>PGDATA</> is set.
|
|
Also specify the name of the particular database you want to work in.
|
|
</para>
|
|
|
|
<para>
|
|
Normally, the single-user mode server treats newline as the command
|
|
entry terminator; there is no intelligence about semicolons,
|
|
as there is in <application>psql</>. To continue a command
|
|
across multiple lines, you must type backslash just before each
|
|
newline except the last one.
|
|
</para>
|
|
|
|
<para>
|
|
But if you use the <option>-j</> command line switch, then newline does
|
|
not terminate command entry. In this case, the server will read the standard input
|
|
until the end-of-file (<acronym>EOF</>) marker, then
|
|
process the input as a single command string. Backslash-newline is not
|
|
treated specially in this case.
|
|
</para>
|
|
|
|
<para>
|
|
To quit the session, type <acronym>EOF</acronym>
|
|
(<keycombo action="simul"><keycap>Control</><keycap>D</></>, usually).
|
|
If you've
|
|
used <option>-j</>, two consecutive <acronym>EOF</>s are needed to exit.
|
|
</para>
|
|
|
|
<para>
|
|
Note that the single-user mode server does not provide sophisticated
|
|
line-editing features (no command history, for example).
|
|
Single-User mode also does not do any background processing, like
|
|
automatic checkpoints.
|
|
|
|
</para>
|
|
</refsect1>
|
|
|
|
<refsect1 id="app-postgres-examples">
|
|
<title>Examples</title>
|
|
|
|
<para>
|
|
To start <command>postgres</command> in the background
|
|
using default values, type:
|
|
|
|
<screen>
|
|
<prompt>$</prompt> <userinput>nohup postgres >logfile 2>&1 </dev/null &</userinput>
|
|
</screen>
|
|
</para>
|
|
|
|
<para>
|
|
To start <command>postgres</command> with a specific
|
|
port, e.g. 1234:
|
|
<screen>
|
|
<prompt>$</prompt> <userinput>postgres -p 1234</userinput>
|
|
</screen>
|
|
To connect to this server using <application>psql</>, specify this port with the -p option:
|
|
<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>postgres -c work_mem=1234</userinput>
|
|
<prompt>$</prompt> <userinput>postgres --work-mem=1234</userinput>
|
|
</screen>
|
|
Either form overrides whatever setting might exist for
|
|
<varname>work_mem</> in <filename>postgresql.conf</>. Notice that
|
|
underscores in parameter names can be written as either underscore
|
|
or dash on the command line. 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>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>See Also</title>
|
|
|
|
<para>
|
|
<xref linkend="app-initdb">,
|
|
<xref linkend="app-pg-ctl">
|
|
</para>
|
|
</refsect1>
|
|
</refentry>
|