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165565cd94
WAL and the interaction of the new full_page_writes parameter with PITR. The too-small WAL first sect1 has been merged with the one following sect1 for clarity. Some minor comments have been made in the WAL config section also. Passes SGML make and proofread for typos. Files changed: patching file doc/src/sgml/backup.sgml patching file doc/src/sgml/config.sgml patching file doc/src/sgml/wal.sgml Simon Riggs
4270 lines
174 KiB
Plaintext
4270 lines
174 KiB
Plaintext
<!--
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$PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.26 2005/10/13 17:32:42 momjian Exp $
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-->
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<chapter Id="runtime-config">
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<title>Run-time Configuration</title>
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<indexterm>
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<primary>configuration</primary>
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<secondary>of the server</secondary>
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</indexterm>
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<para>
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There are many configuration parameters that affect the behavior of
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the database system. In the first section of this chapter, we
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describe how to set configuration chapters. The subsequent sections
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discuss each parameter in detail.
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</para>
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<sect1 id="config-setting">
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<title>Setting Parameters</title>
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<para>
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All parameter names are case-insensitive. Every parameter takes a
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value of one of four types: boolean, integer, floating point,
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or string. Boolean values may be written as <literal>ON</literal>,
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<literal>OFF</literal>, <literal>TRUE</literal>,
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<literal>FALSE</literal>, <literal>YES</literal>,
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<literal>NO</literal>, <literal>1</literal>, <literal>0</literal>
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(all case-insensitive) or any unambiguous prefix of these.
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</para>
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<para>
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One way to set these parameters is to edit the file
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<filename>postgresql.conf</><indexterm><primary>postgresql.conf</></>,
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which is normally kept in the data directory. (<command>initdb</>
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installs a default copy there.) An example of what this file might look
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like is:
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<programlisting>
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# This is a comment
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log_connections = yes
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log_destination = 'syslog'
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search_path = '$user, public'
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</programlisting>
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One parameter is specified per line. The equal sign between name and
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value is optional. Whitespace is insignificant and blank lines are
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ignored. Hash marks (<literal>#</literal>) introduce comments
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anywhere. Parameter values that are not simple identifiers or
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numbers must be single-quoted. To embed a single quote in a parameter
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value, write either two quotes (preferred) or backslash-quote.
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</para>
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<para>
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<indexterm>
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<primary>SIGHUP</primary>
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</indexterm>
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The configuration file is reread whenever the
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<command>postmaster</command> process receives a
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<systemitem>SIGHUP</> signal (which is most easily sent by means
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of <literal>pg_ctl reload</>). The <command>postmaster</command>
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also propagates this signal to all currently running server
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processes so that existing sessions also get the new
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value. Alternatively, you can send the signal to a single server
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process directly. Some parameters can only be set at server start;
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any changes to their entries in the configuration file will be ignored
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until the server is restarted.
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</para>
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<para>
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A second way to set these configuration parameters is to give them
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as a command line option to the <command>postmaster</command>, such as:
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<programlisting>
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postmaster -c log_connections=yes -c log_destination='syslog'
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</programlisting>
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Command-line options override any conflicting settings in
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<filename>postgresql.conf</filename>. Note that this means you won't
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be able to change the value on-the-fly by editing
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<filename>postgresql.conf</filename>, so while the command-line
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method may be convenient, it can cost you flexibility later.
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</para>
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<para>
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Occasionally it is useful to give a command line option to
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one particular session only. The environment variable
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<envar>PGOPTIONS</envar> can be used for this purpose on the
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client side:
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<programlisting>
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env PGOPTIONS='-c geqo=off' psql
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</programlisting>
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(This works for any <application>libpq</>-based client application, not
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just <application>psql</application>.) Note that this won't work for
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parameters that are fixed when the server is started or that must be
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specified in <filename>postgresql.conf</filename>.
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</para>
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<para>
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Furthermore, it is possible to assign a set of option settings to
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a user or a database. Whenever a session is started, the default
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settings for the user and database involved are loaded. The
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commands <xref linkend="sql-alteruser" endterm="sql-alteruser-title">
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and <xref linkend="sql-alterdatabase" endterm="sql-alterdatabase-title">,
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respectively, are used to configure these settings. Per-database
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settings override anything received from the
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<command>postmaster</command> command-line or the configuration
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file, and in turn are overridden by per-user settings; both are
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overridden by per-session options.
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</para>
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<para>
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Some parameters can be changed in individual <acronym>SQL</acronym>
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sessions with the <xref linkend="SQL-SET" endterm="SQL-SET-title">
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command, for example:
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<screen>
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SET ENABLE_SEQSCAN TO OFF;
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</screen>
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If <command>SET</> is allowed, it overrides all other sources of
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values for the parameter. Some parameters cannot be changed via
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<command>SET</command>: for example, if they control behavior that
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cannot reasonably be changed without restarting
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<productname>PostgreSQL</productname>. Also, some parameters can
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be modified via <command>SET</command> or <command>ALTER</> by superusers,
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but not by ordinary users.
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</para>
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<para>
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The <xref linkend="SQL-SHOW" endterm="SQL-SHOW-title">
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command allows inspection of the current values of all parameters.
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</para>
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<para>
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The virtual table <structname>pg_settings</structname>
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(described in <xref linkend="view-pg-settings">) also allows
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displaying and updating session run-time parameters. It is equivalent
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to <command>SHOW</> and <command>SET</>, but can be more convenient
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to use because it can be joined with other tables, or selected from using
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any desired selection condition.
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</para>
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</sect1>
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<sect1 id="runtime-config-file-locations">
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<title>File Locations</title>
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<para>
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In addition to the <filename>postgresql.conf</filename> file
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already mentioned, <productname>PostgreSQL</productname> uses
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two other manually-edited configuration files, which control
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client authentication (their use is discussed in <xref
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linkend="client-authentication">). By default, all three
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configuration files are stored in the database cluster's data
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directory. The options described in this section allow the
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configuration files to be placed elsewhere. (Doing so can ease
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administration. In particular it is often easier to ensure that
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the configuration files are properly backed-up when they are
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kept separate.)
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</para>
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<variablelist>
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<varlistentry id="guc-data-directory" xreflabel="data_directory">
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<term><varname>data_directory</varname> (<type>string</type>)</term>
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<indexterm>
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<primary><varname>data_directory</> configuration parameter</primary>
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</indexterm>
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<listitem>
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<para>
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Specifies the directory to use for data storage.
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This option can only be set at server start.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="guc-config-file" xreflabel="config_file">
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<term><varname>config_file</varname> (<type>string</type>)</term>
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<indexterm>
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<primary><varname>config_file</> configuration parameter</primary>
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</indexterm>
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<listitem>
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<para>
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Specifies the main server configuration file
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(customarily called <filename>postgresql.conf</>).
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This option can only be set on the postmaster command line.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="guc-hba-file" xreflabel="hba_file">
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<term><varname>hba_file</varname> (<type>string</type>)</term>
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<indexterm>
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<primary><varname>hba_file</> configuration parameter</primary>
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</indexterm>
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<listitem>
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<para>
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Specifies the configuration file for host-based authentication
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(customarily called <filename>pg_hba.conf</>).
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This option can only be set at server start.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="guc-ident-file" xreflabel="ident_file">
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<term><varname>ident_file</varname> (<type>string</type>)</term>
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<indexterm>
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<primary><varname>ident_file</> configuration parameter</primary>
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</indexterm>
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<listitem>
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<para>
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Specifies the configuration file for
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<application>ident</> authentication
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(customarily called <filename>pg_ident.conf</>).
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This option can only be set at server start.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="guc-external-pid-file" xreflabel="external_pid_file">
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<term><varname>external_pid_file</varname> (<type>string</type>)</term>
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<indexterm>
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<primary><varname>external_pid_file</> configuration parameter</primary>
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</indexterm>
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<listitem>
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<para>
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Specifies the name of an additional process-id (PID) file that the
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<application>postmaster</> should create for use by server
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administration programs.
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This option can only be set at server start.
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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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In a default installation, none of the above options are set explicitly.
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Instead, the
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data directory is specified by the <option>-D</option> command-line
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option or the <envar>PGDATA</envar> environment variable, and the
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configuration files are all found within the data directory.
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</para>
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<para>
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If you wish to keep the configuration files elsewhere than the
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data directory, the postmaster's <option>-D</option>
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command-line option or <envar>PGDATA</envar> environment variable
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must point to the directory containing the configuration files,
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and the <varname>data_directory</> option must be set in
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<filename>postgresql.conf</filename> (or on the command line) to show
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where the data directory is actually located. Notice that
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<varname>data_directory</> overrides <option>-D</option> and
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<envar>PGDATA</envar> for the location
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of the data directory, but not for the location of the configuration
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files.
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</para>
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<para>
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If you wish, you can specify the configuration file names and locations
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individually using the options <varname>config_file</>,
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<varname>hba_file</> and/or <varname>ident_file</>.
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<varname>config_file</> can only be specified on the
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<command>postmaster</command> command line, but the others can be
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set within the main configuration file. If all three options plus
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<varname>data_directory</> are explicitly set, then it is not necessary
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to specify <option>-D</option> or <envar>PGDATA</envar>.
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</para>
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<para>
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When setting any of these options, a relative path will be interpreted
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with respect to the directory in which the <command>postmaster</command>
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is started.
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</para>
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</sect1>
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<sect1 id="runtime-config-connection">
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<title>Connections and Authentication</title>
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<sect2 id="runtime-config-connection-settings">
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<title>Connection Settings</title>
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<variablelist>
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<varlistentry id="guc-listen-addresses" xreflabel="listen_addresses">
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<term><varname>listen_addresses</varname> (<type>string</type>)</term>
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<indexterm>
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<primary><varname>listen_addresses</> configuration parameter</primary>
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</indexterm>
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<listitem>
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<para>
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Specifies the TCP/IP address(es) on which the server is
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to listen for connections from client applications.
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The value takes the form of a comma-separated list of host names
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and/or numeric IP addresses. The special entry <literal>*</>
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corresponds to all available IP interfaces.
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If the list is empty, the server does not listen on any IP interface
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at all, in which case only Unix-domain sockets can be used to connect
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to it.
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The default value is <systemitem class="systemname">localhost</>,
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which allows only local <quote>loopback</> connections to be made.
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This parameter can only be set at server start.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="guc-port" xreflabel="port">
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<term><varname>port</varname> (<type>integer</type>)</term>
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<indexterm>
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<primary><varname>port</> configuration parameter</primary>
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</indexterm>
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<listitem>
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<para>
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The TCP port the server listens on; 5432 by default. Note that the
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same port number is used for all IP addresses the server listens on.
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This parameter can only be set at server start.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="guc-max-connections" xreflabel="max_connections">
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<term><varname>max_connections</varname> (<type>integer</type>)</term>
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<indexterm>
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<primary><varname>max_connections</> configuration parameter</primary>
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</indexterm>
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<listitem>
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<para>
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Determines the maximum number of concurrent connections to the
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database server. The default is typically 100, but may be less
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if your kernel settings will not support it (as determined
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during <application>initdb</>). This parameter can only be
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set at server start.
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</para>
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<para>
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Increasing this parameter may cause <productname>PostgreSQL</>
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to request more <systemitem class="osname">System V</> shared
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memory or semaphores than your operating system's default configuration
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allows. See <xref linkend="sysvipc"> for information on how to
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adjust those parameters, if necessary.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="guc-superuser-reserved-connections"
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xreflabel="superuser_reserved_connections">
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<term><varname>superuser_reserved_connections</varname>
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(<type>integer</type>)</term>
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<indexterm>
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<primary><varname>superuser_reserved_connections</> configuration parameter</primary>
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</indexterm>
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<listitem>
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<para>
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Determines the number of connection <quote>slots</quote> that
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are reserved for connections by <productname>PostgreSQL</>
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superusers. At most <xref linkend="guc-max-connections">
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connections can ever be active simultaneously. Whenever the
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number of active concurrent connections is at least
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<varname>max_connections</> minus
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<varname>superuser_reserved_connections</varname>, new
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connections will be accepted only for superusers.
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</para>
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<para>
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The default value is 2. The value must be less than the value of
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<varname>max_connections</varname>. This parameter can only be
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set at server start.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="guc-unix-socket-directory" xreflabel="unix_socket_directory">
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<term><varname>unix_socket_directory</varname> (<type>string</type>)</term>
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<indexterm>
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<primary><varname>unix_socket_directory</> configuration parameter</primary>
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</indexterm>
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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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server 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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This parameter can only be set at server start.
|
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="guc-unix-socket-group" xreflabel="unix_socket_group">
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<term><varname>unix_socket_group</varname> (<type>string</type>)</term>
|
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<indexterm>
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<primary><varname>unix_socket_group</> configuration parameter</primary>
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</indexterm>
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<listitem>
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<para>
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Sets the owning group of the Unix-domain socket. (The owning
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user of the socket is always the user that starts the
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server.) In combination with the option
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<varname>unix_socket_permissions</varname> this can be used as
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an additional access control mechanism for Unix-domain connections.
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By default this is the empty string, which uses the default
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group for the current user. This option can only be set at
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server start.
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</para>
|
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</listitem>
|
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</varlistentry>
|
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<varlistentry id="guc-unix-socket-permissions" xreflabel="unix_socket_permissions">
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|
<term><varname>unix_socket_permissions</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>unix_socket_permissions</> configuration parameter</primary>
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</indexterm>
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<listitem>
|
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<para>
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Sets the access permissions of the Unix-domain socket. Unix-domain
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|
sockets use the usual Unix file system permission set.
|
|
The option value is expected to be a numeric mode
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|
specification in the form accepted by the
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|
<function>chmod</function> and <function>umask</function>
|
|
system calls. (To use the customary octal format the number
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|
must start with a <literal>0</literal> (zero).)
|
|
</para>
|
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|
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<para>
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The default permissions are <literal>0777</literal>, meaning
|
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anyone can connect. Reasonable alternatives are
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<literal>0770</literal> (only user and group, see also
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<varname>unix_socket_group</varname>) and <literal>0700</literal>
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|
(only user). (Note that for a Unix-domain socket, only write
|
|
permission matters and so there is no point in setting or revoking
|
|
read or execute permissions.)
|
|
</para>
|
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|
|
<para>
|
|
This access control mechanism is independent of the one
|
|
described in <xref linkend="client-authentication">.
|
|
</para>
|
|
|
|
<para>
|
|
This option can only be set at server start.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-bonjour-name" xreflabel="bonjour_name">
|
|
<term><varname>bonjour_name</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>bonjour_name</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Specifies the <productname>Bonjour</productname> broadcast
|
|
name. By default, the computer name is used, specified as an
|
|
empty string ''. This option is ignored if the server was not
|
|
compiled with <productname>Bonjour</productname> support. This
|
|
option can only be set at server start.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-tcp-keepalives-idle" xreflabel="tcp_keepalives_idle">
|
|
<term><varname>tcp_keepalives_idle</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>tcp_keepalives_idle</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
On systems that support the TCP_KEEPIDLE socket option, specifies the
|
|
number of seconds between sending keepalives on an otherwise idle
|
|
connection. A value of 0 uses the system default. If TCP_KEEPIDLE is
|
|
not supported, this parameter must be 0. This option is ignored for
|
|
connections made via a Unix-domain socket.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
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|
|
<varlistentry id="guc-tcp-keepalives-interval" xreflabel="tcp_keepalives_interval">
|
|
<term><varname>tcp_keepalives_interval</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>tcp_keepalives_interval</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
On systems that support the TCP_KEEPINTVL socket option, specifies how
|
|
long, in seconds, to wait for a response to a keepalive before
|
|
retransmitting. A value of 0 uses the system default. If TCP_KEEPINTVL
|
|
is not supported, this parameter must be 0. This option is ignored
|
|
for connections made via a Unix-domain socket.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-tcp-keepalives-count" xreflabel="tcp_keepalives_count">
|
|
<term><varname>tcp_keepalives_count</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>tcp_keepalives_count</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
On systems that support the TCP_KEEPCNT socket option, specifies how
|
|
many keepalives may be lost before the connection is considered dead.
|
|
A value of 0 uses the system default. If TCP_KEEPCNT is not
|
|
supported, this parameter must be 0. This option is ignored
|
|
for connections made via a Unix-domain socket.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
<sect2 id="runtime-config-connection-security">
|
|
<title>Security and Authentication</title>
|
|
|
|
<variablelist>
|
|
<varlistentry id="guc-authentication-timeout" xreflabel="authentication_timeout">
|
|
<term><varname>authentication_timeout</varname> (<type>integer</type>)</term>
|
|
<indexterm><primary>timeout</><secondary>client authentication</></indexterm>
|
|
<indexterm><primary>client authentication</><secondary>timeout during</></indexterm>
|
|
<indexterm>
|
|
<primary><varname>authentication_timeout</> configuration parameter</primary>
|
|
</indexterm>
|
|
|
|
<listitem>
|
|
<para>
|
|
Maximum time to complete client authentication, in seconds. If a
|
|
would-be client has not completed the authentication protocol in
|
|
this much time, the server breaks the connection. This prevents
|
|
hung clients from occupying a connection indefinitely. This
|
|
option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> file. The default is 60.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-ssl" xreflabel="ssl">
|
|
<term><varname>ssl</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>ssl</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Enables <acronym>SSL</> connections. Please read
|
|
<xref linkend="ssl-tcp"> before using this. The default
|
|
is <literal>off</>. This parameter can only be set at server
|
|
start.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-password-encryption" xreflabel="password_encryption">
|
|
<term><varname>password_encryption</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>password_encryption</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
When a password is specified in <xref
|
|
linkend="sql-createuser" endterm="sql-createuser-title"> or
|
|
<xref linkend="sql-alteruser" endterm="sql-alteruser-title">
|
|
without writing either <literal>ENCRYPTED</> or
|
|
<literal>UNENCRYPTED</>, this option determines whether the
|
|
password is to be encrypted. The default is <literal>on</>
|
|
(encrypt the password).
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-krb-server-keyfile" xreflabel="krb_server_keyfile">
|
|
<term><varname>krb_server_keyfile</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>krb_server_keyfile</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the location of the Kerberos server key file. See
|
|
<xref linkend="kerberos-auth"> for details. This parameter
|
|
can only be set at server start.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-krb-srvname" xreflabel="krb_srvname">
|
|
<term><varname>krb_srvname</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>krb_srvname</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the Kerberos service name. See <xref linkend="kerberos-auth">
|
|
for details. This parameter can only be set at server start.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-krb-server-hostname" xreflabel="krb_server_hostname">
|
|
<term><varname>krb_server_hostname</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>krb_server_hostname</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the hostname part of the service principal.
|
|
This, combined with <varname>krb_srvname</>, is used to generate
|
|
the complete service principal, that is
|
|
<varname>krb_srvname</><literal>/</><varname>krb_server_hostname</><literal>@</>REALM.
|
|
</para>
|
|
<para>
|
|
If not set, the default is to allow any service principal matching an entry
|
|
in the keytab. See <xref linkend="kerberos-auth"> for details.
|
|
This parameter can only be set at server start.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-krb-caseins-users" xreflabel="krb_caseins_users">
|
|
<term><varname>krb_caseins_users</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>krb_caseins_users</varname> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets whether Kerberos usernames should be treated case-insensitively.
|
|
The default is <literal>off</> (case sensitive). This parameter
|
|
can only be set at server start.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-db-user-namespace" xreflabel="db_user_namespace">
|
|
<term><varname>db_user_namespace</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>db_user_namespace</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
This enables per-database user names. It is off by default.
|
|
</para>
|
|
|
|
<para>
|
|
If this is on, you should create users as <literal>username@dbname</>.
|
|
When <literal>username</> is passed by a connecting client,
|
|
<literal>@</> and the database name are appended to the user
|
|
name and that database-specific user name is looked up by the
|
|
server. Note that when you create users with names containing
|
|
<literal>@</> within the SQL environment, you will need to
|
|
quote the user name.
|
|
</para>
|
|
|
|
<para>
|
|
With this option enabled, you can still create ordinary global
|
|
users. Simply append <literal>@</> when specifying the user
|
|
name in the client. The <literal>@</> will be stripped off
|
|
before the user name is looked up by the server.
|
|
</para>
|
|
|
|
<note>
|
|
<para>
|
|
This feature is intended as a temporary measure until a
|
|
complete solution is found. At that time, this option will
|
|
be removed.
|
|
</para>
|
|
</note>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
</sect1>
|
|
|
|
<sect1 id="runtime-config-resource">
|
|
<title>Resource Consumption</title>
|
|
|
|
<sect2 id="runtime-config-resource-memory">
|
|
<title>Memory</title>
|
|
|
|
<variablelist>
|
|
<varlistentry id="guc-shared-buffers" xreflabel="shared_buffers">
|
|
<term><varname>shared_buffers</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>shared_buffers</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the number of shared memory buffers used by the database
|
|
server. The default is typically 1000, but may be less if your
|
|
kernel settings will not support it (as determined during
|
|
<application>initdb</>). Each buffer is 8192 bytes, unless a
|
|
different value of <symbol>BLCKSZ</symbol> was chosen when building
|
|
the server. This setting must be at least 16, as well as at
|
|
least twice the value of <xref linkend="guc-max-connections">;
|
|
however, settings significantly higher than the minimum are
|
|
usually needed for good performance. Values of a few thousand
|
|
are recommended for production installations. This option can
|
|
only be set at server start.
|
|
</para>
|
|
|
|
<para>
|
|
Increasing this parameter may cause <productname>PostgreSQL</>
|
|
to request more <systemitem class="osname">System V</> shared
|
|
memory than your operating system's default configuration
|
|
allows. See <xref linkend="sysvipc"> for information on how to
|
|
adjust those parameters, if necessary.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-temp-buffers" xreflabel="temp_buffers">
|
|
<term><varname>temp_buffers</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>temp_buffers</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the maximum number of temporary buffers used by each database
|
|
session. These are session-local buffers used only for access
|
|
to temporary tables. The default is 1000. The setting can
|
|
be changed within individual sessions, but only up until the
|
|
first use of temporary tables within a session; subsequent
|
|
attempts to change the value will have no effect on that session.
|
|
</para>
|
|
|
|
<para>
|
|
A session will allocate temporary buffers as needed up to the limit
|
|
given by <varname>temp_buffers</>. The cost of setting a large
|
|
value in sessions that do not actually need a lot of temporary
|
|
buffers is only a buffer descriptor, or about 64 bytes, per
|
|
increment in <varname>temp_buffers</>. However if a buffer is
|
|
actually used an additional 8192 bytes will be consumed for it
|
|
(or in general, <symbol>BLCKSZ</symbol> bytes).
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-max-prepared-transactions" xreflabel="max_prepared_transactions">
|
|
<term><varname>max_prepared_transactions</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>max_prepared_transactions</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the maximum number of transactions that can be in the
|
|
<quote>prepared</> state simultaneously (see <xref
|
|
linkend="sql-prepare-transaction"
|
|
endterm="sql-prepare-transaction-title">).
|
|
Setting this parameter to zero disables the prepared-transaction
|
|
feature.
|
|
The default is 5.
|
|
This option can only be set at server start.
|
|
</para>
|
|
|
|
<para>
|
|
If you are not using prepared transactions, this parameter may as
|
|
well be set to zero. If you are using them, you will probably
|
|
want <varname>max_prepared_transactions</varname> to be at least
|
|
as large as <xref linkend="guc-max-connections">, to avoid unwanted
|
|
failures at the prepare step.
|
|
</para>
|
|
|
|
<para>
|
|
Increasing this parameter may cause <productname>PostgreSQL</>
|
|
to request more <systemitem class="osname">System V</> shared
|
|
memory than your operating system's default configuration
|
|
allows. See <xref linkend="sysvipc"> for information on how to
|
|
adjust those parameters, if necessary.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-work-mem" xreflabel="work_mem">
|
|
<term><varname>work_mem</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>work_mem</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Specifies the amount of memory to be used by internal sort operations
|
|
and hash tables before switching to temporary disk files. The value is
|
|
specified in kilobytes, and defaults to 1024 kilobytes (1 MB).
|
|
Note that for a complex query, several sort or hash operations might be
|
|
running in parallel; each one will be allowed to use as much memory
|
|
as this value specifies before it starts to put data into temporary
|
|
files. Also, several running sessions could be doing such operations
|
|
concurrently. So the total memory used could be many
|
|
times the value of <varname>work_mem</varname>; it is necessary to
|
|
keep this fact in mind when choosing the value. Sort operations are
|
|
used for <literal>ORDER BY</>, <literal>DISTINCT</>, and
|
|
merge joins.
|
|
Hash tables are used in hash joins, hash-based aggregation, and
|
|
hash-based processing of <literal>IN</> subqueries.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-maintenance-work-mem" xreflabel="maintenance_work_mem">
|
|
<term><varname>maintenance_work_mem</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>maintenance_work_mem</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Specifies the maximum amount of memory to be used in maintenance
|
|
operations, such as <command>VACUUM</command>, <command>CREATE
|
|
INDEX</>, and <command>ALTER TABLE ADD FOREIGN KEY</>.
|
|
The value is specified in kilobytes, and defaults to 16384 kilobytes
|
|
(16 MB). Since only one of these operations can be executed at
|
|
a time by a database session, and an installation normally doesn't
|
|
have very many of them happening concurrently, it's safe to set this
|
|
value significantly larger than <varname>work_mem</varname>. Larger
|
|
settings may improve performance for vacuuming and for restoring
|
|
database dumps.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-max-stack-depth" xreflabel="max_stack_depth">
|
|
<term><varname>max_stack_depth</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>max_stack_depth</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Specifies the maximum safe depth of the server's execution stack.
|
|
The ideal setting for this parameter is the actual stack size limit
|
|
enforced by the kernel (as set by <literal>ulimit -s</> or local
|
|
equivalent), less a safety margin of a megabyte or so. The safety
|
|
margin is needed because the stack depth is not checked in every
|
|
routine in the server, but only in key potentially-recursive routines
|
|
such as expression evaluation. Setting the parameter higher than
|
|
the actual kernel limit will mean that a runaway recursive function
|
|
can crash an individual backend process. The default setting is
|
|
2048 KB (two megabytes), which is conservatively small and unlikely
|
|
to risk crashes. However, it may be too small to allow execution
|
|
of complex functions.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
<sect2 id="runtime-config-resource-fsm">
|
|
<title>Free Space Map</title>
|
|
|
|
<indexterm>
|
|
<primary>free space map</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
These parameters control the size of the shared <firstterm>free space
|
|
map</>, which tracks the locations of unused space in the database.
|
|
An undersized free space map may cause the database to consume
|
|
increasing amounts of disk space over time, because free space that
|
|
is not in the map cannot be re-used; instead <productname>PostgreSQL</>
|
|
will request more disk space from the operating system when it needs
|
|
to store new data.
|
|
The last few lines displayed by a database-wide <command>VACUUM VERBOSE</>
|
|
command can help in determining if the current settings are adequate.
|
|
A <literal>NOTICE</> message is also printed during such an operation
|
|
if the current settings are too low.
|
|
</para>
|
|
|
|
<para>
|
|
Increasing these parameters may cause <productname>PostgreSQL</>
|
|
to request more <systemitem class="osname">System V</> shared
|
|
memory than your operating system's default configuration
|
|
allows. See <xref linkend="sysvipc"> for information on how to
|
|
adjust those parameters, if necessary.
|
|
</para>
|
|
|
|
<variablelist>
|
|
<varlistentry id="guc-max-fsm-pages" xreflabel="max_fsm_pages">
|
|
<term><varname>max_fsm_pages</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>max_fsm_pages</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the maximum number of disk pages for which free space will
|
|
be tracked in the shared free-space map. Six bytes of shared memory
|
|
are consumed for each page slot. This setting must be more than
|
|
16 * <varname>max_fsm_relations</varname>. The default is 20000.
|
|
This option can only be set at server start.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-max-fsm-relations" xreflabel="max_fsm_relations">
|
|
<term><varname>max_fsm_relations</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>max_fsm_relations</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the maximum number of relations (tables and indexes) for which
|
|
free space will be tracked in the shared free-space map. Roughly
|
|
seventy bytes of shared memory are consumed for each slot.
|
|
The default is 1000.
|
|
This option can only be set at server start.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
<sect2 id="runtime-config-resource-kernel">
|
|
<title>Kernel Resource Usage</title>
|
|
<variablelist>
|
|
|
|
<varlistentry id="guc-max-files-per-process" xreflabel="max_files_per_process">
|
|
<term><varname>max_files_per_process</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>max_files_per_process</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the maximum number of simultaneously open files allowed to each
|
|
server subprocess. The default is 1000. If the kernel is enforcing
|
|
a safe per-process limit, you don't need to worry about this setting.
|
|
But on some platforms (notably, most BSD systems), the kernel will
|
|
allow individual processes to open many more files than the system
|
|
can really support when a large number of processes all try to open
|
|
that many files. If you find yourself seeing <quote>Too many open
|
|
files</> failures, try reducing this setting.
|
|
This option can only be set at server start.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-preload-libraries" xreflabel="preload_libraries">
|
|
<term><varname>preload_libraries</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>preload_libraries</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
This variable specifies one or more shared libraries that are
|
|
to be preloaded at server start. A parameterless
|
|
initialization function can optionally be called for each
|
|
library. To specify that, add a colon and the name of the
|
|
initialization function after the library name. For example
|
|
<literal>'$libdir/mylib:mylib_init'</literal> would cause
|
|
<literal>mylib</> to be preloaded and <literal>mylib_init</>
|
|
to be executed. If more than one library is to be loaded,
|
|
separate their names with commas.
|
|
</para>
|
|
|
|
<para>
|
|
If a specified library or initialization function is not found,
|
|
the server will fail to start.
|
|
</para>
|
|
|
|
<para>
|
|
<productname>PostgreSQL</productname> procedural language
|
|
libraries may be preloaded in this way, typically by using the
|
|
syntax <literal>'$libdir/plXXX:plXXX_init'</literal> where
|
|
<literal>XXX</literal> is <literal>pgsql</>, <literal>perl</>,
|
|
<literal>tcl</>, or <literal>python</>.
|
|
</para>
|
|
|
|
<para>
|
|
By preloading a shared library (and initializing it if
|
|
applicable), the library startup time is avoided when the
|
|
library is first used. However, the time to start each new
|
|
server process may increase slightly, even if that process never
|
|
uses the library. So this option is recommended only for
|
|
libraries that will be used in most sessions.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
|
|
<sect2 id="runtime-config-resource-vacuum-cost">
|
|
<title id="runtime-config-resource-vacuum-cost-title">
|
|
Cost-Based Vacuum Delay
|
|
</title>
|
|
|
|
<para>
|
|
During the execution of <xref linkend="sql-vacuum"
|
|
endterm="sql-vacuum-title"> and <xref linkend="sql-analyze"
|
|
endterm="sql-analyze-title"> commands, the system maintains an
|
|
internal counter that keeps track of the estimated cost of the
|
|
various I/O operations that are performed. When the accumulated
|
|
cost reaches a limit (specified by
|
|
<varname>vacuum_cost_limit</varname>), the process performing
|
|
the operation will sleep for a while (specified by
|
|
<varname>vacuum_cost_delay</varname>). Then it will reset the
|
|
counter and continue execution.
|
|
</para>
|
|
|
|
<para>
|
|
The intent of this feature is to allow administrators to reduce
|
|
the I/O impact of these commands on concurrent database
|
|
activity. There are many situations in which it is not very
|
|
important that maintenance commands like
|
|
<command>VACUUM</command> and <command>ANALYZE</command> finish
|
|
quickly; however, it is usually very important that these
|
|
commands do not significantly interfere with the ability of the
|
|
system to perform other database operations. Cost-based vacuum
|
|
delay provides a way for administrators to achieve this.
|
|
</para>
|
|
|
|
<para>
|
|
This feature is disabled by default. To enable it, set the
|
|
<varname>vacuum_cost_delay</varname> variable to a nonzero
|
|
value.
|
|
</para>
|
|
|
|
<variablelist>
|
|
<varlistentry id="guc-vacuum-cost-delay" xreflabel="vacuum_cost_delay">
|
|
<term><varname>vacuum_cost_delay</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>vacuum_cost_delay</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
The length of time, in milliseconds, that the process will sleep
|
|
when the cost limit has been exceeded.
|
|
The default value is 0, which disables the cost-based vacuum
|
|
delay feature. Positive values enable cost-based vacuuming.
|
|
Note that on many systems, the effective resolution
|
|
of sleep delays is 10 milliseconds; setting
|
|
<varname>vacuum_cost_delay</varname> to a value that is
|
|
not a multiple of 10 may have the same results as setting it
|
|
to the next higher multiple of 10.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-vacuum-cost-page-hit" xreflabel="vacuum_cost_page_hit">
|
|
<term><varname>vacuum_cost_page_hit</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>vacuum_cost_page_hit</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
The estimated cost for vacuuming a buffer found in the shared buffer
|
|
cache. It represents the cost to lock the buffer pool, lookup
|
|
the shared hash table and scan the content of the page. The
|
|
default value is 1.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-vacuum-cost-page-miss" xreflabel="vacuum_cost_page_miss">
|
|
<term><varname>vacuum_cost_page_miss</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>vacuum_cost_page_miss</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
The estimated cost for vacuuming a buffer that has to be read from
|
|
disk. This represents the effort to lock the buffer pool,
|
|
lookup the shared hash table, read the desired block in from
|
|
the disk and scan its content. The default value is 10.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-vacuum-cost-page-dirty" xreflabel="vacuum_cost_page_dirty">
|
|
<term><varname>vacuum_cost_page_dirty</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>vacuum_cost_page_dirty</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
The estimated cost charged when vacuum modifies a block that was
|
|
previously clean. It represents the extra I/O required to
|
|
flush the dirty block out to disk again. The default value is
|
|
20.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-vacuum-cost-limit" xreflabel="vacuum_cost_limit">
|
|
<term><varname>vacuum_cost_limit</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>vacuum_cost_limit</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
The accumulated cost that will cause the vacuuming process to sleep.
|
|
The default value is 200.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
|
|
<note>
|
|
<para>
|
|
There are certain operations that hold critical locks and should
|
|
therefore complete as quickly as possible. Cost-based vacuum
|
|
delays do not occur during such operations. Therefore it is
|
|
possible that the cost accumulates far higher than the specified
|
|
limit. To avoid uselessly long delays in such cases, the actual
|
|
delay is calculated as <varname>vacuum_cost_delay</varname> *
|
|
<varname>accumulated_balance</varname> /
|
|
<varname>vacuum_cost_limit</varname> with a maximum of
|
|
<varname>vacuum_cost_delay</varname> * 4.
|
|
</para>
|
|
</note>
|
|
</sect2>
|
|
|
|
<sect2 id="runtime-config-resource-background-writer">
|
|
<title>Background Writer</title>
|
|
|
|
<para>
|
|
Beginning in <productname>PostgreSQL</> 8.0, there is a separate server
|
|
process called the <firstterm>background writer</>, whose sole function
|
|
is to issue writes of <quote>dirty</> shared buffers. The intent is
|
|
that server processes handling user queries should seldom or never have
|
|
to wait for a write to occur, because the background writer will do it.
|
|
This arrangement also reduces the performance penalty associated with
|
|
checkpoints. The background writer will continuously trickle out dirty
|
|
pages to disk, so that only a few pages will need to be forced out when
|
|
checkpoint time arrives, instead of the storm of dirty-buffer writes that
|
|
formerly occurred at each checkpoint. However there is a net overall
|
|
increase in I/O load, because where a repeatedly-dirtied page might
|
|
before have been written only once per checkpoint interval, the
|
|
background writer might write it several times in the same interval.
|
|
In most situations a continuous low load is preferable to periodic
|
|
spikes, but the parameters discussed in this subsection can be used to tune
|
|
the behavior for local needs.
|
|
</para>
|
|
|
|
<variablelist>
|
|
<varlistentry id="guc-bgwriter-delay" xreflabel="bgwriter_delay">
|
|
<term><varname>bgwriter_delay</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>bgwriter_delay</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Specifies the delay between activity rounds for the
|
|
background writer. In each round the writer issues writes
|
|
for some number of dirty buffers (controllable by the
|
|
following parameters). It then sleeps for <varname>bgwriter_delay</>
|
|
milliseconds, and repeats. The default value is 200. Note
|
|
that on many systems, the effective resolution of sleep
|
|
delays is 10 milliseconds; setting <varname>bgwriter_delay</>
|
|
to a value that is not a multiple of 10 may have the same
|
|
results as setting it to the next higher multiple of 10.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-bgwriter-lru-percent" xreflabel="bgwriter_lru_percent">
|
|
<term><varname>bgwriter_lru_percent</varname> (<type>floating point</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>bgwriter_lru_percent</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
To reduce the probability that server processes will need to issue
|
|
their own writes, the background writer tries to write buffers that
|
|
are likely to be recycled soon. In each round, it examines up to
|
|
<varname>bgwriter_lru_percent</> of the buffers that are nearest to
|
|
being recycled, and writes any that are dirty.
|
|
The default value is 1.0 (this is a percentage of the total number
|
|
of shared buffers).
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-bgwriter-lru-maxpages" xreflabel="bgwriter_lru_maxpages">
|
|
<term><varname>bgwriter_lru_maxpages</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>bgwriter_lru_maxpages</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
In each round, no more than this many buffers will be written
|
|
as a result of scanning soon-to-be-recycled buffers.
|
|
The default value is 5.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-bgwriter-all-percent" xreflabel="bgwriter_all_percent">
|
|
<term><varname>bgwriter_all_percent</varname> (<type>floating point</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>bgwriter_all_percent</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
To reduce the amount of work that will be needed at checkpoint time,
|
|
the background writer also does a circular scan through the entire
|
|
buffer pool, writing buffers that are found to be dirty.
|
|
In each round, it examines up to
|
|
<varname>bgwriter_all_percent</> of the buffers for this purpose.
|
|
The default value is 0.333 (this is a percentage of the total number
|
|
of shared buffers). With the default <varname>bgwriter_delay</>
|
|
setting, this will allow the entire shared buffer pool to be scanned
|
|
about once per minute.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-bgwriter-all-maxpages" xreflabel="bgwriter_all_maxpages">
|
|
<term><varname>bgwriter_all_maxpages</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>bgwriter_all_maxpages</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
In each round, no more than this many buffers will be written
|
|
as a result of the scan of the entire buffer pool. (If this
|
|
limit is reached, the scan stops, and resumes at the next buffer
|
|
during the next round.)
|
|
The default value is 5.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
|
|
<para>
|
|
Smaller values of <varname>bgwriter_all_percent</varname> and
|
|
<varname>bgwriter_all_maxpages</varname> reduce the extra I/O load
|
|
caused by the background writer, but leave more work to be done
|
|
at checkpoint time. To reduce load spikes at checkpoints,
|
|
increase these two values.
|
|
Similarly, smaller values of <varname>bgwriter_lru_percent</varname> and
|
|
<varname>bgwriter_lru_maxpages</varname> reduce the extra I/O load
|
|
caused by the background writer, but make it more likely that server
|
|
processes will have to issue writes for themselves, delaying interactive
|
|
queries.
|
|
To disable background writing entirely,
|
|
set both <varname>maxpages</varname> values and/or both
|
|
<varname>percent</varname> values to zero.
|
|
</para>
|
|
</sect2>
|
|
</sect1>
|
|
|
|
<sect1 id="runtime-config-wal">
|
|
<title>Write Ahead Log</title>
|
|
|
|
<para>
|
|
See also <xref linkend="wal-configuration"> for details on WAL
|
|
tuning.
|
|
</para>
|
|
|
|
<sect2 id="runtime-config-wal-settings">
|
|
<title>Settings</title>
|
|
<variablelist>
|
|
|
|
<varlistentry id="guc-fsync" xreflabel="fsync">
|
|
<indexterm>
|
|
<primary><varname>fsync</> configuration parameter</primary>
|
|
</indexterm>
|
|
<term><varname>fsync</varname> (<type>boolean</type>)</term>
|
|
<listitem>
|
|
<para>
|
|
If this option is on, the <productname>PostgreSQL</> server
|
|
will use the <function>fsync()</> system call in several places
|
|
to make sure that updates are physically written to disk. This
|
|
insures that a database cluster will recover to a
|
|
consistent state after an operating system or hardware crash.
|
|
</para>
|
|
|
|
<para>
|
|
However, using <function>fsync()</function> results in a
|
|
performance penalty: when a transaction is committed,
|
|
<productname>PostgreSQL</productname> must wait for the
|
|
operating system to flush the write-ahead log to disk. When
|
|
<varname>fsync</varname> is disabled, the operating system is
|
|
allowed to do its best in buffering, ordering, and delaying
|
|
writes. This can result in significantly improved performance.
|
|
However, if the system crashes, the results of the last few
|
|
committed transactions may be lost in part or whole. In the
|
|
worst case, unrecoverable data corruption may occur.
|
|
(Crashes of the database server itself are <emphasis>not</>
|
|
a risk factor here. Only an operating-system-level crash
|
|
creates a risk of corruption.)
|
|
</para>
|
|
|
|
<para>
|
|
Due to the risks involved, there is no universally correct
|
|
setting for <varname>fsync</varname>. Some administrators
|
|
always disable <varname>fsync</varname>, while others only
|
|
turn it off for bulk loads, where there is a clear restart
|
|
point if something goes wrong, whereas some administrators
|
|
always leave <varname>fsync</varname> enabled. The default is
|
|
to enable <varname>fsync</varname>, for maximum reliability.
|
|
If you trust your operating system, your hardware, and your
|
|
utility company (or your battery backup), you can consider
|
|
disabling <varname>fsync</varname>.
|
|
</para>
|
|
|
|
<para>
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> file. If this option
|
|
is <literal>off</>, consider also turning off
|
|
<varname>guc-full-page-writes</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-wal-sync-method" xreflabel="wal_sync_method">
|
|
<term><varname>wal_sync_method</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>wal_sync_method</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Method used for forcing WAL updates out to disk. Possible
|
|
values are:
|
|
</para>
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para>
|
|
<literal>open_datasync</> (write WAL files with <function>open()</> option <symbol>O_DSYNC</>)
|
|
</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>
|
|
<literal>fdatasync</> (call <function>fdatasync()</> at each commit),
|
|
</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>
|
|
<literal>fsync</> (call <function>fsync()</> at each commit)
|
|
</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>
|
|
<literal>fsync_writethrough</> (force write-through of any disk write cache)
|
|
</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>
|
|
<literal>open_sync</> (write WAL files with <function>open()</> option <symbol>O_SYNC</>)
|
|
</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
<para>
|
|
Not all of these choices are available on all platforms.
|
|
The top-most supported option is used as the default.
|
|
If <varname>fsync</varname> is off then this setting is irrelevant.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-full-page-writes" xreflabel="full_page_writes">
|
|
<indexterm>
|
|
<primary><varname>full_page_writes</> configuration parameter</primary>
|
|
</indexterm>
|
|
<term><varname>full_page_writes</varname> (<type>boolean</type>)</term>
|
|
<listitem>
|
|
<para>
|
|
A page write in process during an operating system crash might
|
|
be only partially written to disk, leading to an on-disk page
|
|
that contains a mix of old and new data. During recovery, the
|
|
row changes stored in WAL are not enough to completely restore
|
|
the page.
|
|
</para>
|
|
|
|
<para>
|
|
When this option is on, the <productname>PostgreSQL</> server
|
|
writes full pages to WAL when they are first modified after a
|
|
checkpoint so crash recovery is possible. Turning this option off
|
|
might lead to a corrupt system after an operating system crash
|
|
or power failure because uncorrected partial pages might contain
|
|
inconsistent or corrupt data. The risks are less but similar to
|
|
<varname>fsync</>.
|
|
</para>
|
|
|
|
<para>
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> file. The default is
|
|
<literal>on</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-wal-buffers" xreflabel="wal_buffers">
|
|
<term><varname>wal_buffers</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>wal_buffers</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Number of disk-page buffers allocated in shared memory for WAL data.
|
|
The default is 8. The setting need only be large enough to hold
|
|
the amount of WAL data generated by one typical transaction, since
|
|
the data is flushed to disk at every transaction commit.
|
|
This option can only be set at server start.
|
|
</para>
|
|
|
|
<para>
|
|
Increasing this parameter may cause <productname>PostgreSQL</>
|
|
to request more <systemitem class="osname">System V</> shared
|
|
memory than your operating system's default configuration
|
|
allows. See <xref linkend="sysvipc"> for information on how to
|
|
adjust those parameters, if necessary.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-commit-delay" xreflabel="commit_delay">
|
|
<term><varname>commit_delay</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>commit_delay</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Time delay between writing a commit record to the WAL buffer
|
|
and flushing the buffer out to disk, in microseconds. A
|
|
nonzero delay can allow multiple transactions to be committed
|
|
with only one <function>fsync()</function> system call, if
|
|
system load is high enough that additional transactions become
|
|
ready to commit within the given interval. But the delay is
|
|
just wasted if no other transactions become ready to
|
|
commit. Therefore, the delay is only performed if at least
|
|
<varname>commit_siblings</varname> other transactions are
|
|
active at the instant that a server process has written its
|
|
commit record. The default is zero (no delay).
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-commit-siblings" xreflabel="commit_siblings">
|
|
<term><varname>commit_siblings</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>commit_siblings</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Minimum number of concurrent open transactions to require
|
|
before performing the <varname>commit_delay</> delay. A larger
|
|
value makes it more probable that at least one other
|
|
transaction will become ready to commit during the delay
|
|
interval. The default is five.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
<sect2 id="runtime-config-wal-checkpoints">
|
|
<title>Checkpoints</title>
|
|
|
|
<variablelist>
|
|
<varlistentry id="guc-checkpoint-segments" xreflabel="checkpoint_segments">
|
|
<term><varname>checkpoint_segments</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>checkpoint_segments</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Maximum distance between automatic WAL checkpoints, in log
|
|
file segments (each segment is normally 16 megabytes). The
|
|
default is three. This option can only be set at server start
|
|
or in the <filename>postgresql.conf</filename> file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-checkpoint-timeout" xreflabel="checkpoint_timeout">
|
|
<term><varname>checkpoint_timeout</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>checkpoint_timeout</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Maximum time between automatic WAL checkpoints, in
|
|
seconds. The default is 300 seconds. This option can only be
|
|
set at server start or in the <filename>postgresql.conf</>
|
|
file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-checkpoint-warning" xreflabel="checkpoint_warning">
|
|
<term><varname>checkpoint_warning</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>checkpoint_warning</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Write a message to the server log if checkpoints caused by
|
|
the filling of checkpoint segment files happen closer together
|
|
than this many seconds. The default is 30 seconds.
|
|
Zero turns off the warning.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
<sect2 id="runtime-config-wal-archiving">
|
|
<title>Archiving</title>
|
|
|
|
<variablelist>
|
|
<varlistentry id="guc-archive-command" xreflabel="archive_command">
|
|
<term><varname>archive_command</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>archive_command</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
The shell command to execute to archive a completed segment of
|
|
the WAL file series. If this is an empty string (the default),
|
|
WAL archiving is disabled. Any <literal>%p</> in the string is
|
|
replaced by the absolute path of the file to archive, and any
|
|
<literal>%f</> is replaced by the file name only. Use
|
|
<literal>%%</> to embed an actual <literal>%</> character in the
|
|
command. For more information see <xref
|
|
linkend="backup-archiving-wal">. This option can only be set at
|
|
server start or in the <filename>postgresql.conf</filename>
|
|
file.
|
|
</para>
|
|
<para>
|
|
It is important for the command to return a zero exit status if
|
|
and only if it succeeds. Examples:
|
|
<programlisting>
|
|
archive_command = 'cp "%p" /mnt/server/archivedir/"%f"'
|
|
archive_command = 'copy "%p" /mnt/server/archivedir/"%f"' # Windows
|
|
</programlisting>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
</sect1>
|
|
|
|
<sect1 id="runtime-config-query">
|
|
<title>Query Planning</title>
|
|
|
|
<sect2 id="runtime-config-query-enable">
|
|
<title>Planner Method Configuration</title>
|
|
|
|
<para>
|
|
These configuration parameters provide a crude method of
|
|
influencing the query plans chosen by the query optimizer. If
|
|
the default plan chosen by the optimizer for a particular query
|
|
is not optimal, a temporary solution may be found by using one
|
|
of these configuration parameters to force the optimizer to
|
|
choose a different plan. Turning one of these settings off
|
|
permanently is seldom a good idea, however.
|
|
Better ways to improve the quality of the
|
|
plans chosen by the optimizer include adjusting the <xref
|
|
linkend="runtime-config-query-constants"
|
|
endterm="runtime-config-query-constants-title">, running <xref
|
|
linkend="sql-analyze" endterm="sql-analyze-title"> more
|
|
frequently, increasing the value of the <xref
|
|
linkend="guc-default-statistics-target"> configuration parameter,
|
|
and increasing the amount of statistics collected for
|
|
specific columns using <command>ALTER TABLE SET
|
|
STATISTICS</command>.
|
|
</para>
|
|
|
|
<variablelist>
|
|
<varlistentry id="guc-enable-bitmapscan" xreflabel="enable_bitmapscan">
|
|
<term><varname>enable_bitmapscan</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary>bitmap scan</primary>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary><varname>enable_bitmapscan</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Enables or disables the query planner's use of bitmap-scan plan
|
|
types. The default is <literal>on</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-enable-hashagg" xreflabel="enable_hashagg">
|
|
<term><varname>enable_hashagg</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>enable_hashagg</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Enables or disables the query planner's use of hashed
|
|
aggregation plan types. The default is <literal>on</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-enable-hashjoin" xreflabel="enable_hashjoin">
|
|
<term><varname>enable_hashjoin</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>enable_hashjoin</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Enables or disables the query planner's use of hash-join plan
|
|
types. The default is <literal>on</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-enable-indexscan" xreflabel="enable_indexscan">
|
|
<term><varname>enable_indexscan</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary>index scan</primary>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary><varname>enable_indexscan</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Enables or disables the query planner's use of index-scan plan
|
|
types. The default is <literal>on</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-enable-mergejoin" xreflabel="enable_mergejoin">
|
|
<term><varname>enable_mergejoin</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>enable_mergejoin</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Enables or disables the query planner's use of merge-join plan
|
|
types. The default is <literal>on</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-enable-nestloop" xreflabel="enable_nestloop">
|
|
<term><varname>enable_nestloop</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>enable_nestloop</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Enables or disables the query planner's use of nested-loop join
|
|
plans. It's not possible to suppress nested-loop joins entirely,
|
|
but turning this variable off discourages the planner from using
|
|
one if there are other methods available. The default is
|
|
<literal>on</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-enable-seqscan" xreflabel="enable_seqscan">
|
|
<term><varname>enable_seqscan</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary>sequential scan</primary>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary><varname>enable_seqscan</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Enables or disables the query planner's use of sequential scan
|
|
plan types. It's not possible to suppress sequential scans
|
|
entirely, but turning this variable off discourages the planner
|
|
from using one if there are other methods available. The
|
|
default is <literal>on</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-enable-sort" xreflabel="enable_sort">
|
|
<term><varname>enable_sort</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>enable_sort</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Enables or disables the query planner's use of explicit sort
|
|
steps. It's not possible to suppress explicit sorts entirely,
|
|
but turning this variable off discourages the planner from
|
|
using one if there are other methods available. The default
|
|
is <literal>on</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-enable-tidscan" xreflabel="enable_tidscan">
|
|
<term><varname>enable_tidscan</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>enable_tidscan</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Enables or disables the query planner's use of <acronym>TID</>
|
|
scan plan types. The default is <literal>on</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
<sect2 id="runtime-config-query-constants">
|
|
<title id="runtime-config-query-constants-title">
|
|
Planner Cost Constants
|
|
</title>
|
|
|
|
<note>
|
|
<para>
|
|
Unfortunately, there is no well-defined method for determining
|
|
ideal values for the family of <quote>cost</quote> variables that
|
|
appear below. You are encouraged to experiment and share
|
|
your findings.
|
|
</para>
|
|
</note>
|
|
|
|
<variablelist>
|
|
|
|
<varlistentry id="guc-effective-cache-size" xreflabel="effective_cache_size">
|
|
<term><varname>effective_cache_size</varname> (<type>floating point</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>effective_cache_size</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the planner's assumption about the effective size of the
|
|
disk cache that is available to a single index scan. This is
|
|
factored into estimates of the cost of using an index; a
|
|
higher value makes it more likely index scans will be used, a
|
|
lower value makes it more likely sequential scans will be
|
|
used. When setting this parameter you should consider both
|
|
<productname>PostgreSQL</productname>'s shared buffers and the
|
|
portion of the kernel's disk cache that will be used for
|
|
<productname>PostgreSQL</productname> data files. Also, take
|
|
into account the expected number of concurrent queries using
|
|
different indexes, since they will have to share the available
|
|
space. This parameter has no effect on the size of shared
|
|
memory allocated by <productname>PostgreSQL</productname>, nor
|
|
does it reserve kernel disk cache; it is used only for
|
|
estimation purposes. The value is measured in disk pages,
|
|
which are normally 8192 bytes each. The default is 1000.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-random-page-cost" xreflabel="random_page_cost">
|
|
<term><varname>random_page_cost</varname> (<type>floating point</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>random_page_cost</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the planner's estimate of the cost of a
|
|
nonsequentially fetched disk page. This is measured as a
|
|
multiple of the cost of a sequential page fetch. A higher
|
|
value makes it more likely a sequential scan will be used, a
|
|
lower value makes it more likely an index scan will be
|
|
used. The default is four.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-cpu-tuple-cost" xreflabel="cpu_tuple_cost">
|
|
<term><varname>cpu_tuple_cost</varname> (<type>floating point</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>cpu_tuple_cost</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the planner's estimate of the cost of processing
|
|
each row during a query. This is measured as a fraction of
|
|
the cost of a sequential page fetch. The default is 0.01.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-cpu-index-tuple-cost" xreflabel="cpu_index_tuple_cost">
|
|
<term><varname>cpu_index_tuple_cost</varname> (<type>floating point</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>cpu_index_tuple_cost</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the planner's estimate of the cost of processing
|
|
each index row during an index scan. This is measured as a
|
|
fraction of the cost of a sequential page fetch. The default
|
|
is 0.001.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-cpu-operator-cost" xreflabel="cpu_operator_cost">
|
|
<term><varname>cpu_operator_cost</varname> (<type>floating point</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>cpu_operator_cost</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the planner's estimate of the cost of processing each
|
|
operator in a <literal>WHERE</> clause. This is measured as a fraction of
|
|
the cost of a sequential page fetch. The default is 0.0025.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
|
|
</sect2>
|
|
<sect2 id="runtime-config-query-geqo">
|
|
<title>Genetic Query Optimizer</title>
|
|
|
|
<variablelist>
|
|
|
|
<varlistentry id="guc-geqo" xreflabel="geqo">
|
|
<indexterm>
|
|
<primary>genetic query optimization</primary>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary>GEQO</primary>
|
|
<see>genetic query optimization</see>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary><varname>geqo</> configuration parameter</primary>
|
|
</indexterm>
|
|
<term><varname>geqo</varname> (<type>boolean</type>)</term>
|
|
<listitem>
|
|
<para>
|
|
Enables or disables genetic query optimization, which is an
|
|
algorithm that attempts to do query planning without
|
|
exhaustive searching. This is on by default. The
|
|
<varname>geqo_threshold</varname> variable provides a more
|
|
granular way to disable GEQO for certain classes of queries.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-geqo-threshold" xreflabel="geqo_threshold">
|
|
<term><varname>geqo_threshold</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>geqo_threshold</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Use genetic query optimization to plan queries with at least
|
|
this many <literal>FROM</> items involved. (Note that an outer
|
|
<literal>JOIN</> construct counts as only one <literal>FROM</>
|
|
item.) The default is 12. For simpler queries it is usually best
|
|
to use the deterministic, exhaustive planner, but for queries with
|
|
many tables the deterministic planner takes too long.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-geqo-effort" xreflabel="geqo_effort">
|
|
<term><varname>geqo_effort</varname>
|
|
(<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>geqo_effort</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Controls the trade off between planning time and query plan
|
|
efficiency in GEQO. This variable must be an integer in the
|
|
range from 1 to 10. The default value is 5. Larger values
|
|
increase the time spent doing query planning, but also
|
|
increase the likelihood that an efficient query plan will be
|
|
chosen.
|
|
</para>
|
|
|
|
<para>
|
|
<varname>geqo_effort</varname> doesn't actually do anything
|
|
directly; it is only used to compute the default values for
|
|
the other variables that influence GEQO behavior (described
|
|
below). If you prefer, you can set the other parameters by
|
|
hand instead.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-geqo-pool-size" xreflabel="geqo_pool_size">
|
|
<term><varname>geqo_pool_size</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>geqo_pool_size</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Controls the pool size used by GEQO. The pool size is the
|
|
number of individuals in the genetic population. It must be
|
|
at least two, and useful values are typically 100 to 1000. If
|
|
it is set to zero (the default setting) then a suitable
|
|
default is chosen based on <varname>geqo_effort</varname> and
|
|
the number of tables in the query.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-geqo-generations" xreflabel="geqo_generations">
|
|
<term><varname>geqo_generations</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>geqo_generations</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Controls the number of generations used by GEQO. Generations
|
|
specifies the number of iterations of the algorithm. It must
|
|
be at least one, and useful values are in the same range as
|
|
the pool size. If it is set to zero (the default setting)
|
|
then a suitable default is chosen based on
|
|
<varname>geqo_pool_size</varname>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-geqo-selection-bias" xreflabel="geqo_selection_bias">
|
|
<term><varname>geqo_selection_bias</varname> (<type>floating point</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>geqo_selection_bias</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Controls the selection bias used by GEQO. The selection bias
|
|
is the selective pressure within the population. Values can be
|
|
from 1.50 to 2.00; the latter is the default.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
<sect2 id="runtime-config-query-other">
|
|
<title>Other Planner Options</title>
|
|
|
|
<variablelist>
|
|
|
|
<varlistentry id="guc-default-statistics-target" xreflabel="default_statistics_target">
|
|
<term><varname>default_statistics_target</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>default_statistics_target</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the default statistics target for table columns that have
|
|
not had a column-specific target set via <command>ALTER TABLE
|
|
SET STATISTICS</>. Larger values increase the time needed to
|
|
do <command>ANALYZE</>, but may improve the quality of the
|
|
planner's estimates. The default is 10. For more information
|
|
on the use of statistics by the <productname>PostgreSQL</>
|
|
query planner, refer to <xref linkend="planner-stats">.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-constraint-exclusion" xreflabel="constraint_exclusion">
|
|
<term><varname>constraint_exclusion</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary>constraint exclusion</primary>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary><varname>constraint_exclusion</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Enables or disables the query planner's use of table constraints to
|
|
limit table access. The default is <literal>off</>.
|
|
</para>
|
|
|
|
<para>
|
|
When this parameter is <literal>on</>, the planner compares query
|
|
conditions with table CHECK constraints, and omits scanning tables
|
|
where the conditions contradict the constraints. (Presently
|
|
this is done only for child tables of inheritance scans.) For
|
|
example:
|
|
|
|
<programlisting>
|
|
CREATE TABLE parent(key integer, ...);
|
|
CREATE TABLE child1000(check (key between 1000 and 1999)) INHERITS(parent);
|
|
CREATE TABLE child2000(check (key between 2000 and 2999)) INHERITS(parent);
|
|
...
|
|
SELECT * FROM parent WHERE key = 2400;
|
|
</programlisting>
|
|
|
|
With constraint exclusion enabled, this SELECT will not scan
|
|
<structname>child1000</> at all. This can improve performance when
|
|
inheritance is used to build partitioned tables.
|
|
</para>
|
|
|
|
<para>
|
|
Currently, <varname>constraint_exclusion</> defaults to
|
|
<literal>off</>, because it risks incorrect results if
|
|
query plans are cached --- if a table constraint is changed or dropped,
|
|
the previously generated plan might now be wrong, and there is no
|
|
built-in mechanism to force re-planning. (This deficiency will
|
|
probably be addressed in a future
|
|
<productname>PostgreSQL</productname> release.) Another reason
|
|
for keeping it off is that the constraint checks are relatively
|
|
expensive, and in many circumstances will yield no savings.
|
|
It is recommended to turn this on only if you are actually using
|
|
partitioned tables designed to take advantage of the feature.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-from-collapse-limit" xreflabel="from_collapse_limit">
|
|
<term><varname>from_collapse_limit</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>from_collapse_limit</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
The planner will merge sub-queries into upper queries if the
|
|
resulting <literal>FROM</literal> list would have no more than
|
|
this many items. Smaller values reduce planning time but may
|
|
yield inferior query plans. The default is 8. It is usually
|
|
wise to keep this less than <xref linkend="guc-geqo-threshold">.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-join-collapse-limit" xreflabel="join_collapse_limit">
|
|
<term><varname>join_collapse_limit</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>join_collapse_limit</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
The planner will rewrite explicit inner <literal>JOIN</>
|
|
constructs into lists of <literal>FROM</> items whenever a
|
|
list of no more than this many items in total would
|
|
result. Prior to <productname>PostgreSQL</> 7.4, joins
|
|
specified via the <literal>JOIN</literal> construct would
|
|
never be reordered by the query planner. The query planner has
|
|
subsequently been improved so that inner joins written in this
|
|
form can be reordered; this configuration parameter controls
|
|
the extent to which this reordering is performed.
|
|
<note>
|
|
<para>
|
|
At present, the order of outer joins specified via the
|
|
<literal>JOIN</> construct is never adjusted by the query
|
|
planner; therefore, <varname>join_collapse_limit</> has no
|
|
effect on this behavior. The planner may be improved to
|
|
reorder some classes of outer joins in a future release of
|
|
<productname>PostgreSQL</productname>.
|
|
</para>
|
|
</note>
|
|
</para>
|
|
|
|
<para>
|
|
By default, this variable is set the same as
|
|
<varname>from_collapse_limit</varname>, which is appropriate
|
|
for most uses. Setting it to 1 prevents any reordering of
|
|
inner <literal>JOIN</>s. Thus, the explicit join order
|
|
specified in the query will be the actual order in which the
|
|
relations are joined. The query planner does not always choose
|
|
the optimal join order; advanced users may elect to
|
|
temporarily set this variable to 1, and then specify the join
|
|
order they desire explicitly. Another consequence of setting
|
|
this variable to 1 is that the query planner will behave more
|
|
like the <productname>PostgreSQL</productname> 7.3 query
|
|
planner, which some users might find useful for backward
|
|
compatibility reasons.
|
|
</para>
|
|
|
|
<para>
|
|
Setting this variable to a value between 1 and
|
|
<varname>from_collapse_limit</varname> might be useful to
|
|
trade off planning time against the quality of the chosen plan
|
|
(higher values produce better plans).
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
</sect1>
|
|
|
|
<sect1 id="runtime-config-logging">
|
|
<title>Error Reporting and Logging</title>
|
|
|
|
<indexterm zone="runtime-config-logging">
|
|
<primary>server log</primary>
|
|
</indexterm>
|
|
|
|
<sect2 id="runtime-config-logging-where">
|
|
<title>Where To Log</title>
|
|
|
|
<indexterm zone="runtime-config-logging-where">
|
|
<primary>where to log</primary>
|
|
</indexterm>
|
|
|
|
<variablelist>
|
|
|
|
<varlistentry id="guc-log-destination" xreflabel="log_destination">
|
|
<term><varname>log_destination</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>log_destination</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
<productname>PostgreSQL</productname> supports several methods
|
|
for logging server messages, including
|
|
<systemitem>stderr</systemitem> and
|
|
<systemitem>syslog</systemitem>. On Windows,
|
|
<systemitem>eventlog</systemitem> is also supported. Set this
|
|
option to a list of desired log destinations separated by
|
|
commas. The default is to log to <systemitem>stderr</systemitem>
|
|
only.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> configuration file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-redirect-stderr" xreflabel="redirect_stderr">
|
|
<term><varname>redirect_stderr</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>redirect_stderr</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
This option allows messages sent to <application>stderr</> to be
|
|
captured and redirected into log files.
|
|
This option, in combination with logging to <application>stderr</>,
|
|
is often more useful than
|
|
logging to <application>syslog</>, since some types of messages
|
|
may not appear in <application>syslog</> output (a common example
|
|
is dynamic-linker failure messages).
|
|
This option can only be set at server start.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-log-directory" xreflabel="log_directory">
|
|
<term><varname>log_directory</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>log_directory</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
When <varname>redirect_stderr</> is enabled, this option
|
|
determines the directory in which log files will be created.
|
|
It may be specified as an absolute path, or relative to the
|
|
cluster data directory.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> configuration file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-log-filename" xreflabel="log_filename">
|
|
<term><varname>log_filename</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>log_filename</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
When <varname>redirect_stderr</varname> is enabled, this option
|
|
sets the file names of the created log files. The value
|
|
is treated as a <systemitem>strftime</systemitem> pattern,
|
|
so <literal>%</literal>-escapes
|
|
can be used to specify time-varying file names.
|
|
If no <literal>%</literal>-escapes are present,
|
|
<productname>PostgreSQL</productname> will
|
|
append the epoch of the new log file's open time. For example,
|
|
if <varname>log_filename</varname> were <literal>server_log</literal>, then the
|
|
chosen file name would be <literal>server_log.1093827753</literal>
|
|
for a log starting at Sun Aug 29 19:02:33 2004 MST.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> configuration file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-log-rotation-age" xreflabel="log_rotation_age">
|
|
<term><varname>log_rotation_age</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>log_rotation_age</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
When <varname>redirect_stderr</varname> is enabled, this option
|
|
determines the maximum lifetime of an individual log file.
|
|
After this many minutes have elapsed, a new log file will
|
|
be created. Set to zero to disable time-based creation of
|
|
new log files.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> configuration file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-log-rotation-size" xreflabel="log_rotation_size">
|
|
<term><varname>log_rotation_size</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>log_rotation_size</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
When <varname>redirect_stderr</varname> is enabled, this option
|
|
determines the maximum size of an individual log file.
|
|
After this many kilobytes have been emitted into a log file,
|
|
a new log file will be created. Set to zero to disable size-based
|
|
creation of new log files.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> configuration file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-log-truncate-on-rotation" xreflabel="log_truncate_on_rotation">
|
|
<term><varname>log_truncate_on_rotation</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>log_truncate_on_rotation</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
When <varname>redirect_stderr</varname> is enabled, this option will cause
|
|
<productname>PostgreSQL</productname> to truncate (overwrite),
|
|
rather than append to, any existing log file of the same name.
|
|
However, truncation will occur only when a new file is being opened
|
|
due to time-based rotation, not during server startup or size-based
|
|
rotation. When off, pre-existing files will be appended to in
|
|
all cases. For example, using this option in combination with
|
|
a <varname>log_filename</varname> like <literal>postgresql-%H.log</literal>
|
|
would result in generating twenty-four hourly log files and then
|
|
cyclically overwriting them.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> configuration file.
|
|
</para>
|
|
<para>
|
|
Example: To keep 7 days of logs, one log file per day named
|
|
<literal>server_log.Mon</literal>, <literal>server_log.Tue</literal>,
|
|
etc, and automatically overwrite last week's log with this week's log,
|
|
set <varname>log_filename</varname> to <literal>server_log.%a</literal>,
|
|
<varname>log_truncate_on_rotation</varname> to <literal>on</literal>, and
|
|
<varname>log_rotation_age</varname> to <literal>1440</literal>.
|
|
</para>
|
|
<para>
|
|
Example: To keep 24 hours of logs, one log file per hour, but
|
|
also rotate sooner if the log file size exceeds 1GB, set
|
|
<varname>log_filename</varname> to <literal>server_log.%H%M</literal>,
|
|
<varname>log_truncate_on_rotation</varname> to <literal>on</literal>,
|
|
<varname>log_rotation_age</varname> to <literal>60</literal>, and
|
|
<varname>log_rotation_size</varname> to <literal>1000000</literal>.
|
|
Including <literal>%M</> in <varname>log_filename</varname> allows
|
|
any size-driven rotations that may occur to select a filename
|
|
different from the hour's initial filename.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-syslog-facility" xreflabel="syslog_facility">
|
|
<term><varname>syslog_facility</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>syslog_facility</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
When logging to <application>syslog</> is enabled, this option
|
|
determines the <application>syslog</application>
|
|
<quote>facility</quote> to be used. You may choose
|
|
from <literal>LOCAL0</>, <literal>LOCAL1</>,
|
|
<literal>LOCAL2</>, <literal>LOCAL3</>, <literal>LOCAL4</>,
|
|
<literal>LOCAL5</>, <literal>LOCAL6</>, <literal>LOCAL7</>;
|
|
the default is <literal>LOCAL0</>. See also the
|
|
documentation of your system's
|
|
<application>syslog</application> daemon.
|
|
This option can only be set at server start.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-syslog-ident" xreflabel="syslog_ident">
|
|
<term><varname>syslog_ident</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>syslog_identity</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
When logging to <application>syslog</> is enabled, this option
|
|
determines the program name used to identify
|
|
<productname>PostgreSQL</productname> messages in
|
|
<application>syslog</application> logs. The default is
|
|
<literal>postgres</literal>.
|
|
This option can only be set at server start.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
<sect2 id="runtime-config-logging-when">
|
|
<title>When To Log</title>
|
|
|
|
<variablelist>
|
|
|
|
<varlistentry id="guc-client-min-messages" xreflabel="client_min_messages">
|
|
<term><varname>client_min_messages</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>client_min_messages</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Controls which message levels are sent to the client.
|
|
Valid values are <literal>DEBUG5</>,
|
|
<literal>DEBUG4</>, <literal>DEBUG3</>, <literal>DEBUG2</>,
|
|
<literal>DEBUG1</>, <literal>LOG</>, <literal>NOTICE</>,
|
|
<literal>WARNING</>, and <literal>ERROR</>. Each level
|
|
includes all the levels that follow it. The later the level,
|
|
the fewer messages are sent. The default is
|
|
<literal>NOTICE</>. Note that <literal>LOG</> has a different
|
|
rank here than in <varname>log_min_messages</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-log-min-messages" xreflabel="log_min_messages">
|
|
<term><varname>log_min_messages</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>log_min_messages</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Controls which message levels are written to the server log.
|
|
Valid values are <literal>DEBUG5</>, <literal>DEBUG4</>,
|
|
<literal>DEBUG3</>, <literal>DEBUG2</>, <literal>DEBUG1</>,
|
|
<literal>INFO</>, <literal>NOTICE</>, <literal>WARNING</>,
|
|
<literal>ERROR</>, <literal>LOG</>, <literal>FATAL</>, and
|
|
<literal>PANIC</>. Each level includes all the levels that
|
|
follow it. The later the level, the fewer messages are sent
|
|
to the log. The default is <literal>NOTICE</>. Note that
|
|
<literal>LOG</> has a different rank here than in
|
|
<varname>client_min_messages</>.
|
|
Only superusers can change this setting.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-log-error-verbosity" xreflabel="log_error_verbosity">
|
|
<term><varname>log_error_verbosity</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>log_error_verbosity</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Controls the amount of detail written in the server log for each
|
|
message that is logged. Valid values are <literal>TERSE</>,
|
|
<literal>DEFAULT</>, and <literal>VERBOSE</>, each adding more
|
|
fields to displayed messages.
|
|
Only superusers can change this setting.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-log-min-error-statement" xreflabel="log_min_error_statement">
|
|
<term><varname>log_min_error_statement</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>log_min_error_statement</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Controls whether or not the SQL statement that causes an error
|
|
condition will also be recorded in the server log. All SQL
|
|
statements that cause an error of the specified level or
|
|
higher are logged. The default is
|
|
<literal>PANIC</literal> (effectively turning this feature
|
|
off for normal use). Valid values are <literal>DEBUG5</literal>,
|
|
<literal>DEBUG4</literal>, <literal>DEBUG3</literal>,
|
|
<literal>DEBUG2</literal>, <literal>DEBUG1</literal>,
|
|
<literal>INFO</literal>, <literal>NOTICE</literal>,
|
|
<literal>WARNING</literal>, <literal>ERROR</literal>,
|
|
<literal>FATAL</literal>, and <literal>PANIC</literal>. For
|
|
example, if you set this to <literal>ERROR</literal> then all
|
|
SQL statements causing errors, fatal errors, or panics will be
|
|
logged. Enabling this option can be helpful in tracking down
|
|
the source of any errors that appear in the server log.
|
|
Only superusers can change this setting.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-log-min-duration-statement" xreflabel="log_min_duration_statement">
|
|
<term><varname>log_min_duration_statement</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>log_min_duration_statement</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Logs the statement and its duration on a single log line if its
|
|
duration is greater than or equal to the specified number of
|
|
milliseconds. Setting this to zero will print all statements
|
|
and their durations. Minus-one (the default) disables the
|
|
feature. For example, if you set it to <literal>250</literal>
|
|
then all SQL statements that run 250ms or longer will be
|
|
logged. Enabling this option can be useful in tracking down
|
|
unoptimized queries in your applications. This setting is
|
|
independent of <varname>log_statement</varname> and
|
|
<varname>log_duration</varname>. Only superusers can change
|
|
this setting.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-silent-mode" xreflabel="silent_mode">
|
|
<term><varname>silent_mode</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>silent_mode</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Runs the server silently. If this option is set, the server
|
|
will automatically run in background and any controlling
|
|
terminals are disassociated (same effect as
|
|
<command>postmaster</>'s <option>-S</option> option).
|
|
The server's standard output and standard error are redirected
|
|
to <literal>/dev/null</>, so any messages sent to them will be lost.
|
|
Unless <application>syslog</> logging is selected or
|
|
<varname>redirect_stderr</> is enabled, using this option
|
|
is discouraged because it makes it impossible to see error messages.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
|
|
<para>
|
|
Here is a list of the various message severity levels used in
|
|
these settings:
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><literal>DEBUG[1-5]</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Provides information for use by developers.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>INFO</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Provides information implicitly requested by the user,
|
|
e.g., during <command>VACUUM VERBOSE</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>NOTICE</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Provides information that may be helpful to users, e.g.,
|
|
truncation of long identifiers and the creation of indexes as part
|
|
of primary keys.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>WARNING</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Provides warnings to the user, e.g., <command>COMMIT</>
|
|
outside a transaction block.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>ERROR</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Reports an error that caused the current command to abort.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>LOG</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Reports information of interest to administrators, e.g.,
|
|
checkpoint activity.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>FATAL</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Reports an error that caused the current session to abort.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>PANIC</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Reports an error that caused all sessions to abort.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
|
|
</sect2>
|
|
<sect2 id="runtime-config-logging-what">
|
|
<title>What To Log</title>
|
|
|
|
<variablelist>
|
|
|
|
<varlistentry>
|
|
<term><varname>debug_print_parse</varname> (<type>boolean</type>)</term>
|
|
<term><varname>debug_print_rewritten</varname> (<type>boolean</type>)</term>
|
|
<term><varname>debug_print_plan</varname> (<type>boolean</type>)</term>
|
|
<term><varname>debug_pretty_print</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>debug_print_parse</> configuration parameter</primary>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary><varname>debug_print_rewritten</> configuration parameter</primary>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary><varname>debug_print_plan</> configuration parameter</primary>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary><varname>debug_pretty_print</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
These options enable various debugging output to be emitted.
|
|
For each executed query, they print
|
|
the resulting parse tree, the query rewriter output, or the
|
|
execution plan. <varname>debug_pretty_print</varname> indents
|
|
these displays to produce a more readable but much longer
|
|
output format. <varname>client_min_messages</varname> or
|
|
<varname>log_min_messages</varname> must be
|
|
<literal>DEBUG1</literal> or lower to actually send this output
|
|
to the client or the server log, respectively.
|
|
These options are off by default.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-log-connections" xreflabel="log_connections">
|
|
<term><varname>log_connections</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>log_connections</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
This outputs a line to the server log detailing each successful
|
|
connection. This is off by default, although it is probably very
|
|
useful. Some client programs, like <application>psql</>, attempt
|
|
to connect twice while determining if a password is required, so
|
|
duplicate <quote>connection received</> messages do not
|
|
necessarily indicate a problem. This option can only be set at
|
|
server start or in the <filename>postgresql.conf</> configuration file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-log-disconnections" xreflabel="log_disconnections">
|
|
<term><varname>log_disconnections</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>log_disconnections</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
This outputs a line in the server log similar to
|
|
<varname>log_connections</varname> but at session termination,
|
|
and includes the duration of the session. This is off by
|
|
default. This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> configuration file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
|
|
<varlistentry id="guc-log-duration" xreflabel="log_duration">
|
|
<term><varname>log_duration</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>log_duration</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Causes the duration of every completed statement which satisfies
|
|
<varname>log_statement</> to be logged. When using this option,
|
|
if you are not using <application>syslog</>, it is recommended
|
|
that you log the PID or session ID using <varname>log_line_prefix</>
|
|
so that you can link the statement to the
|
|
duration using the process ID or session ID. The default is
|
|
<literal>off</>. Only superusers can change this setting.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-log-line-prefix" xreflabel="log_line_prefix">
|
|
<term><varname>log_line_prefix</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>log_line_prefix</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
This is a <function>printf</>-style string that is output at the
|
|
beginning of each log line. The default is an empty string.
|
|
Each recognized escape is replaced as outlined
|
|
below - anything else that looks like an escape is ignored. Other
|
|
characters are copied straight to the log line. Some escapes are
|
|
only recognised by session processes, and do not apply to
|
|
background processes such as the postmaster. <application>Syslog</>
|
|
produces its own
|
|
time stamp and process ID information, so you probably do not want to
|
|
use those escapes if you are using <application>syslog</>.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> configuration file.
|
|
|
|
<informaltable>
|
|
<tgroup cols="3">
|
|
<thead>
|
|
<row>
|
|
<entry>Escape</entry>
|
|
<entry>Effect</entry>
|
|
<entry>Session only</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
<row>
|
|
<entry><literal>%u</literal></entry>
|
|
<entry>User name</entry>
|
|
<entry>yes</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%d</literal></entry>
|
|
<entry>Database name</entry>
|
|
<entry>yes</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%r</literal></entry>
|
|
<entry>Remote host name or IP address, and remote port</entry>
|
|
<entry>yes</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%h</literal></entry>
|
|
<entry>Remote Hostname or IP address</entry>
|
|
<entry>yes</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%p</literal></entry>
|
|
<entry>Process ID</entry>
|
|
<entry>no</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%t</literal></entry>
|
|
<entry>Time stamp (no milliseconds)</entry>
|
|
<entry>no</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%m</literal></entry>
|
|
<entry>Time stamp with milliseconds</entry>
|
|
<entry>no</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%i</literal></entry>
|
|
<entry>Command tag: This is the command that generated the log line.</entry>
|
|
<entry>yes</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%c</literal></entry>
|
|
<entry>Session ID: A unique identifier for each session.
|
|
It is 2 4-byte hexadecimal numbers (without leading zeros)
|
|
separated by a dot. The numbers
|
|
are the session start time and the process ID, so this can also
|
|
be used as a space saving way of printing these items.</entry>
|
|
<entry>yes</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%l</literal></entry>
|
|
<entry>Number of the log line for each process, starting at 1</entry>
|
|
<entry>no</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%s</literal></entry>
|
|
<entry>Session start time stamp</entry>
|
|
<entry>yes</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%x</literal></entry>
|
|
<entry>Transaction ID</entry>
|
|
<entry>yes</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%q</literal></entry>
|
|
<entry>Does not produce any output, but tells non-session
|
|
processes to stop at this point in the string. Ignored by
|
|
session processes.</entry>
|
|
<entry>no</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%%</literal></entry>
|
|
<entry>Literal <literal>%</></entry>
|
|
<entry>no</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</informaltable>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-log-statement" xreflabel="log_statement">
|
|
<term><varname>log_statement</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>log_statement</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Controls which SQL statements are logged. Valid values are
|
|
<literal>none</>, <literal>ddl</>, <literal>mod</>, and
|
|
<literal>all</>. <literal>ddl</> logs all data definition
|
|
commands like <literal>CREATE</>, <literal>ALTER</>, and
|
|
<literal>DROP</> commands. <literal>mod</> logs all
|
|
<literal>ddl</> statements, plus <literal>INSERT</>,
|
|
<literal>UPDATE</>, <literal>DELETE</>, <literal>TRUNCATE</>,
|
|
and <literal>COPY FROM</>. <literal>PREPARE</> and
|
|
<literal>EXPLAIN ANALYZE</> statements are also logged if their
|
|
contained command is of an appropriate type.
|
|
</para>
|
|
<para>
|
|
The default is <literal>none</>. Only superusers can change this
|
|
setting.
|
|
</para>
|
|
|
|
<note>
|
|
<para>
|
|
The <command>EXECUTE</command> statement is not considered a
|
|
<literal>ddl</> or <literal>mod</> statement. When it is logged,
|
|
only the name of the prepared statement is reported, not the
|
|
actual prepared statement.
|
|
</para>
|
|
|
|
<para>
|
|
When a function is defined in the
|
|
<application>PL/pgSQL</application>server-side language, any queries
|
|
executed by the function will only be logged the first time that the
|
|
function is invoked in a particular session. This is because
|
|
<application>PL/pgSQL</application> keeps a cache of the
|
|
query plans produced for the SQL statements in the function.
|
|
</para>
|
|
</note>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-log-hostname" xreflabel="log_hostname">
|
|
<term><varname>log_hostname</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>log_hostname</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
By default, connection log messages only show the IP address of the
|
|
connecting host. Turning on this option causes logging of the
|
|
host name as well. Note that depending on your host name resolution
|
|
setup this might impose a non-negligible performance penalty. This
|
|
option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
</sect1>
|
|
|
|
<sect1 id="runtime-config-statistics">
|
|
<title>Runtime Statistics</title>
|
|
|
|
<sect2 id="runtime-config-statistics-monitor">
|
|
<title>Statistics Monitoring</title>
|
|
<variablelist>
|
|
|
|
<varlistentry>
|
|
<term><varname>log_statement_stats</varname> (<type>boolean</type>)</term>
|
|
<term><varname>log_parser_stats</varname> (<type>boolean</type>)</term>
|
|
<term><varname>log_planner_stats</varname> (<type>boolean</type>)</term>
|
|
<term><varname>log_executor_stats</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>log_statement_stats</> configuration parameter</primary>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary><varname>log_parser_stats</> configuration parameter</primary>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary><varname>log_planner_stats</> configuration parameter</primary>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary><varname>log_executor_stats</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
For each query, write performance statistics of the respective
|
|
module to the server log. This is a crude profiling
|
|
instrument. <varname>log_statement_stats</varname> reports total
|
|
statement statistics, while the others report per-module statistics.
|
|
<varname>log_statement_stats</varname> cannot be enabled together with
|
|
any of the per-module options. All of these options are disabled by
|
|
default. Only superusers can change these settings.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
|
|
</sect2>
|
|
<sect2 id="runtime-config-statistics-collector">
|
|
<title>Query and Index Statistics Collector</title>
|
|
<variablelist>
|
|
|
|
<varlistentry id="guc-stats-start-collector" xreflabel="stats_start_collector">
|
|
<term><varname>stats_start_collector</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>stats_start_collector</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Controls whether the server should start the
|
|
statistics-collection subprocess. This is on by default, but
|
|
may be turned off if you know you have no interest in
|
|
collecting statistics. This option can only be set at server
|
|
start.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-stats-command-string" xreflabel="stats_command_string">
|
|
<term><varname>stats_command_string</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>stats_command_string</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Enables the collection of statistics on the currently
|
|
executing command of each session, along with the time at
|
|
which that command began execution. This option is off by
|
|
default. Note that even when enabled, this information is not
|
|
visible to all users, only to superusers and the user owning
|
|
the session being reported on; so it should not represent a
|
|
security risk. This data can be accessed via the
|
|
<structname>pg_stat_activity</structname> system view; refer
|
|
to <xref linkend="monitoring"> for more information.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-stats-block-level" xreflabel="stats_block_level">
|
|
<term><varname>stats_block_level</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>stats_block_level</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Enables the collection of block-level statistics on database
|
|
activity. This option is disabled by default. If this option
|
|
is enabled, the data that is produced can be accessed via the
|
|
<structname>pg_stat</structname> and
|
|
<structname>pg_statio</structname> family of system views;
|
|
refer to <xref linkend="monitoring"> for more information.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-stats-row-level" xreflabel="stats_row_level">
|
|
<term><varname>stats_row_level</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>stats_row_level</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Enables the collection of row-level statistics on database
|
|
activity. This option is disabled by default. If this option
|
|
is enabled, the data that is produced can be accessed via the
|
|
<structname>pg_stat</structname> and
|
|
<structname>pg_statio</structname> family of system views;
|
|
refer to <xref linkend="monitoring"> for more information.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-stats-reset-on-server-start" xreflabel="stats_reset_on_server_start">
|
|
<term><varname>stats_reset_on_server_start</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>stats_reset_on_server_start</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
If on, collected statistics are zeroed out whenever the server
|
|
is restarted. If off, statistics are accumulated across server
|
|
restarts. The default is <literal>off</>. This option can only
|
|
be set at server start.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
</sect1>
|
|
|
|
<sect1 id="runtime-config-autovacuum">
|
|
<title>Automatic Vacuuming</title>
|
|
|
|
<indexterm>
|
|
<primary>autovacuum</primary>
|
|
<secondary>global configuration parameters</secondary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
These settings control the default behavior for the <firstterm>autovacuum
|
|
daemon</firstterm>. Please refer to <xref linkend="autovacuum"> for
|
|
more information.
|
|
</para>
|
|
|
|
<variablelist>
|
|
|
|
<varlistentry id="guc-autovacuum" xreflabel="autovacuum">
|
|
<term><varname>autovacuum</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>autovacuum</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Controls whether the server should start the
|
|
autovacuum subprocess. This is off by default.
|
|
<varname>stats_start_collector</> and <varname>stats_row_level</>
|
|
must also be on for this to start.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-autovacuum-naptime" xreflabel="autovacuum_naptime">
|
|
<term><varname>autovacuum_naptime</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>autovacuum_naptime</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Specifies the delay between activity rounds for the autovacuum
|
|
subprocess. In each round the subprocess examines one database
|
|
and issues <command>VACUUM</> and <command>ANALYZE</> commands
|
|
as needed for tables in that database. The delay is measured
|
|
in seconds, and the default is 60.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-autovacuum-vacuum-threshold" xreflabel="autovacuum_vacuum_threshold">
|
|
<term><varname>autovacuum_vacuum_threshold</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>autovacuum_vacuum_threshold</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Specifies the minimum number of updated or deleted tuples needed
|
|
to trigger a <command>VACUUM</> in any one table.
|
|
The default is 1000.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> file.
|
|
This setting can be overridden for individual tables by entries in
|
|
<structname>pg_autovacuum</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-autovacuum-analyze-threshold" xreflabel="autovacuum_analyze_threshold">
|
|
<term><varname>autovacuum_analyze_threshold</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>autovacuum_analyze_threshold</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Specifies the minimum number of inserted, updated or deleted tuples
|
|
needed to trigger an <command>ANALYZE</> in any one table.
|
|
The default is 500.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> file.
|
|
This setting can be overridden for individual tables by entries in
|
|
<structname>pg_autovacuum</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-autovacuum-vacuum-scale-factor" xreflabel="autovacuum_vacuum_scale_factor">
|
|
<term><varname>autovacuum_vacuum_scale_factor</varname> (<type>floating point</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>autovacuum_vacuum_scale_factor</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Specifies a fraction of the table size to add to
|
|
<varname>autovacuum_vacuum_threshold</varname>
|
|
when deciding whether to trigger a <command>VACUUM</>.
|
|
The default is 0.4.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> file.
|
|
This setting can be overridden for individual tables by entries in
|
|
<structname>pg_autovacuum</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-autovacuum-analyze-scale-factor" xreflabel="autovacuum_analyze_scale_factor">
|
|
<term><varname>autovacuum_analyze_scale_factor</varname> (<type>floating point</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>autovacuum_analyze_scale_factor</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Specifies a fraction of the table size to add to
|
|
<varname>autovacuum_analyze_threshold</varname>
|
|
when deciding whether to trigger an <command>ANALYZE</>.
|
|
The default is 0.2.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> file.
|
|
This setting can be overridden for individual tables by entries in
|
|
<structname>pg_autovacuum</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-autovacuum-vacuum-cost-delay" xreflabel="autovacuum_vacuum_cost_delay">
|
|
<term><varname>autovacuum_vacuum_cost_delay</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>autovacuum_vacuum_cost_delay</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Specifies the cost delay value that will be used in automatic
|
|
<command>VACUUM</> operations. If -1 is specified (which is the
|
|
default), the regular
|
|
<xref linkend="guc-vacuum-cost-delay"> value will be used.
|
|
This setting can be overridden for individual tables by entries in
|
|
<structname>pg_autovacuum</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-autovacuum-vacuum-cost-limit" xreflabel="autovacuum_vacuum_cost_limit">
|
|
<term><varname>autovacuum_vacuum_cost_limit</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>autovacuum_vacuum_cost_limit</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Specifies the cost limit value that will be used in automatic
|
|
<command>VACUUM</> operations. If -1 is specified (which is the
|
|
default), the regular
|
|
<xref linkend="guc-vacuum-cost-limit"> value will be used.
|
|
This setting can be overridden for individual tables by entries in
|
|
<structname>pg_autovacuum</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect1>
|
|
|
|
<sect1 id="runtime-config-client">
|
|
<title>Client Connection Defaults</title>
|
|
|
|
<sect2 id="runtime-config-client-statement">
|
|
<title>Statement Behavior</title>
|
|
<variablelist>
|
|
|
|
<varlistentry id="guc-search-path" xreflabel="search_path">
|
|
<term><varname>search_path</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>search_path</> configuration parameter</primary>
|
|
</indexterm>
|
|
<indexterm><primary>path</><secondary>for schemas</></>
|
|
<listitem>
|
|
<para>
|
|
This variable specifies the order in which schemas are searched
|
|
when an object (table, data type, function, etc.) is referenced by a
|
|
simple name with no schema component. When there are objects of
|
|
identical names in different schemas, the one found first
|
|
in the search path is used. An object that is not in any of the
|
|
schemas in the search path can only be referenced by specifying
|
|
its containing schema with a qualified (dotted) name.
|
|
</para>
|
|
|
|
<para>
|
|
The value for <varname>search_path</varname> has to be a comma-separated
|
|
list of schema names. If one of the list items is
|
|
the special value <literal>$user</literal>, then the schema
|
|
having the name returned by <function>SESSION_USER</> is substituted, if there
|
|
is such a schema. (If not, <literal>$user</literal> is ignored.)
|
|
</para>
|
|
|
|
<para>
|
|
The system catalog schema, <literal>pg_catalog</>, is always
|
|
searched, whether it is mentioned in the path or not. If it is
|
|
mentioned in the path then it will be searched in the specified
|
|
order. If <literal>pg_catalog</> is not in the path then it will
|
|
be searched <emphasis>before</> searching any of the path items.
|
|
It should also be noted that the temporary-table schema,
|
|
<literal>pg_temp_<replaceable>nnn</></>, is implicitly searched before any of
|
|
these.
|
|
</para>
|
|
|
|
<para>
|
|
When objects are created without specifying a particular target
|
|
schema, they will be placed in the first schema listed
|
|
in the search path. An error is reported if the search path is
|
|
empty.
|
|
</para>
|
|
|
|
<para>
|
|
The default value for this parameter is
|
|
<literal>'$user, public'</literal> (where the second part will be
|
|
ignored if there is no schema named <literal>public</>).
|
|
This supports shared use of a database (where no users
|
|
have private schemas, and all share use of <literal>public</>),
|
|
private per-user schemas, and combinations of these. Other
|
|
effects can be obtained by altering the default search path
|
|
setting, either globally or per-user.
|
|
</para>
|
|
|
|
<para>
|
|
The current effective value of the search path can be examined
|
|
via the <acronym>SQL</acronym> function
|
|
<function>current_schemas()</>. This is not quite the same as
|
|
examining the value of <varname>search_path</varname>, since
|
|
<function>current_schemas()</> shows how the requests
|
|
appearing in <varname>search_path</varname> were resolved.
|
|
</para>
|
|
|
|
<para>
|
|
For more information on schema handling, see <xref linkend="ddl-schemas">.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-default-tablespace" xreflabel="default_tablespace">
|
|
<term><varname>default_tablespace</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>default_tablespace</> configuration parameter</primary>
|
|
</indexterm>
|
|
<indexterm><primary>tablespace</><secondary>default</></>
|
|
<listitem>
|
|
<para>
|
|
This variable specifies the default tablespace in which to create
|
|
objects (tables and indexes) when a <command>CREATE</> command does
|
|
not explicitly specify a tablespace.
|
|
</para>
|
|
|
|
<para>
|
|
The value is either the name of a tablespace, or an empty string
|
|
to specify using the default tablespace of the current database.
|
|
If the value does not match the name of any existing tablespace,
|
|
<productname>PostgreSQL</> will automatically use the default
|
|
tablespace of the current database.
|
|
</para>
|
|
|
|
<para>
|
|
For more information on tablespaces,
|
|
see <xref linkend="manage-ag-tablespaces">.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-check-function-bodies" xreflabel="check_function_bodies">
|
|
<term><varname>check_function_bodies</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>check_function_bodies</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
This parameter is normally on. When set to <literal>off</>, it
|
|
disables validation of the function body string during <xref
|
|
linkend="sql-createfunction"
|
|
endterm="sql-createfunction-title">. Disabling validation is
|
|
occasionally useful to avoid problems such as forward references
|
|
when restoring function definitions from a dump.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-default-transaction-isolation" xreflabel="default_transaction_isolation">
|
|
<indexterm>
|
|
<primary>transaction isolation level</primary>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary><varname>default_transaction_isolation</> configuration parameter</primary>
|
|
</indexterm>
|
|
<term><varname>default_transaction_isolation</varname> (<type>string</type>)</term>
|
|
<listitem>
|
|
<para>
|
|
Each SQL transaction has an isolation level, which can be
|
|
either <quote>read uncommitted</quote>, <quote>read
|
|
committed</quote>, <quote>repeatable read</quote>, or
|
|
<quote>serializable</quote>. This parameter controls the
|
|
default isolation level of each new transaction. The default
|
|
is <quote>read committed</quote>.
|
|
</para>
|
|
|
|
<para>
|
|
Consult <xref linkend="mvcc"> and <xref
|
|
linkend="sql-set-transaction"
|
|
endterm="sql-set-transaction-title"> for more information.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-default-transaction-read-only" xreflabel="default_transaction_read_only">
|
|
<indexterm>
|
|
<primary>read-only transaction</primary>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary><varname>default_transaction_read_only</> configuration parameter</primary>
|
|
</indexterm>
|
|
|
|
<term><varname>default_transaction_read_only</varname> (<type>boolean</type>)</term>
|
|
<listitem>
|
|
<para>
|
|
A read-only SQL transaction cannot alter non-temporary tables.
|
|
This parameter controls the default read-only status of each new
|
|
transaction. The default is <literal>off</> (read/write).
|
|
</para>
|
|
|
|
<para>
|
|
Consult <xref linkend="sql-set-transaction"
|
|
endterm="sql-set-transaction-title"> for more information.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-statement-timeout" xreflabel="statement_timeout">
|
|
<term><varname>statement_timeout</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>statement_timeout</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Abort any statement that takes over the specified number of
|
|
milliseconds. If <varname>log_min_error_statement</> is set to
|
|
<literal>ERROR</> or lower, the statement that timed out will also be
|
|
logged. A value of zero (the default) turns off the
|
|
limitation.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
<sect2 id="runtime-config-client-format">
|
|
<title>Locale and Formatting</title>
|
|
|
|
<variablelist>
|
|
|
|
<varlistentry id="guc-datestyle" xreflabel="DateStyle">
|
|
<term><varname>DateStyle</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>DateStyle</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the display format for date and time values, as well as the
|
|
rules for interpreting ambiguous date input values. For
|
|
historical reasons, this variable contains two independent
|
|
components: the output format specification (<literal>ISO</>,
|
|
<literal>Postgres</>, <literal>SQL</>, or <literal>German</>)
|
|
and the input/output specification for year/month/day ordering
|
|
(<literal>DMY</>, <literal>MDY</>, or <literal>YMD</>). These
|
|
can be set separately or together. The keywords <literal>Euro</>
|
|
and <literal>European</> are synonyms for <literal>DMY</>; the
|
|
keywords <literal>US</>, <literal>NonEuro</>, and
|
|
<literal>NonEuropean</> are synonyms for <literal>MDY</>. See
|
|
<xref linkend="datatype-datetime"> for more information. The
|
|
default is <literal>ISO, MDY</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-timezone" xreflabel="timezone">
|
|
<term><varname>timezone</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>timezone</> configuration parameter</primary>
|
|
</indexterm>
|
|
<indexterm><primary>time zone</></>
|
|
<listitem>
|
|
<para>
|
|
Sets the time zone for displaying and interpreting time
|
|
stamps. The default is 'unknown', which means to use whatever
|
|
the system environment specifies as the time zone. See <xref
|
|
linkend="datatype-datetime"> for more information.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-australian-timezones" xreflabel="australian_timezones">
|
|
<term><varname>australian_timezones</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>australian_timezones</> configuration parameter</primary>
|
|
</indexterm>
|
|
<indexterm><primary>time zone</><secondary>Australian</></>
|
|
<listitem>
|
|
<para>
|
|
If set to on, <literal>ACST</literal>,
|
|
<literal>CST</literal>, <literal>EST</literal>, and
|
|
<literal>SAT</literal> are interpreted as Australian time
|
|
zones rather than as North/South American time zones and
|
|
Saturday. The default is <literal>off</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-extra-float-digits" xreflabel="extra_float_digits">
|
|
<indexterm>
|
|
<primary>significant digits</primary>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary>floating-point</primary>
|
|
<secondary>display</secondary>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary><varname>extra_float_digits</> configuration parameter</primary>
|
|
</indexterm>
|
|
|
|
<term><varname>extra_float_digits</varname> (<type>integer</type>)</term>
|
|
<listitem>
|
|
<para>
|
|
This parameter adjusts the number of digits displayed for
|
|
floating-point values, including <type>float4</>, <type>float8</>,
|
|
and geometric data types. The parameter value is added to the
|
|
standard number of digits (<literal>FLT_DIG</> or <literal>DBL_DIG</>
|
|
as appropriate). The value can be set as high as 2, to include
|
|
partially-significant digits; this is especially useful for dumping
|
|
float data that needs to be restored exactly. Or it can be set
|
|
negative to suppress unwanted digits.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-client-encoding" xreflabel="client_encoding">
|
|
<term><varname>client_encoding</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>client_encoding</> configuration parameter</primary>
|
|
</indexterm>
|
|
<indexterm><primary>character set</></>
|
|
<listitem>
|
|
<para>
|
|
Sets the client-side encoding (character set).
|
|
The default is to use the database encoding.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-lc-messages" xreflabel="lc_messages">
|
|
<term><varname>lc_messages</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>lc_messages</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the language in which messages are displayed. Acceptable
|
|
values are system-dependent; see <xref linkend="locale"> for
|
|
more information. If this variable is set to the empty string
|
|
(which is the default) then the value is inherited from the
|
|
execution environment of the server in a system-dependent way.
|
|
</para>
|
|
|
|
<para>
|
|
On some systems, this locale category does not exist. Setting
|
|
this variable will still work, but there will be no effect.
|
|
Also, there is a chance that no translated messages for the
|
|
desired language exist. In that case you will continue to see
|
|
the English messages.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-lc-monetary" xreflabel="lc_monetary">
|
|
<term><varname>lc_monetary</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>lc_monetary</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the locale to use for formatting monetary amounts, for
|
|
example with the <function>to_char</function> family of
|
|
functions. Acceptable values are system-dependent; see <xref
|
|
linkend="locale"> for more information. If this variable is
|
|
set to the empty string (which is the default) then the value
|
|
is inherited from the execution environment of the server in a
|
|
system-dependent way.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-lc-numeric" xreflabel="lc_numeric">
|
|
<term><varname>lc_numeric</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>lc_numeric</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the locale to use for formatting numbers, for example
|
|
with the <function>to_char</function> family of
|
|
functions. Acceptable values are system-dependent; see <xref
|
|
linkend="locale"> for more information. If this variable is
|
|
set to the empty string (which is the default) then the value
|
|
is inherited from the execution environment of the server in a
|
|
system-dependent way.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-lc-time" xreflabel="lc_time">
|
|
<term><varname>lc_time</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>lc_time</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Sets the locale to use for formatting date and time values.
|
|
(Currently, this setting does nothing, but it may in the
|
|
future.) Acceptable values are system-dependent; see <xref
|
|
linkend="locale"> for more information. If this variable is
|
|
set to the empty string (which is the default) then the value
|
|
is inherited from the execution environment of the server in a
|
|
system-dependent way.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
|
|
</sect2>
|
|
<sect2 id="runtime-config-client-other">
|
|
<title>Other Defaults</title>
|
|
|
|
<variablelist>
|
|
|
|
<varlistentry id="guc-explain-pretty-print" xreflabel="explain_pretty_print">
|
|
<term><varname>explain_pretty_print</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>explain_pretty_print</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Determines whether <command>EXPLAIN VERBOSE</> uses the
|
|
indented or non-indented format for displaying detailed
|
|
query-tree dumps. The default is <literal>on</>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-dynamic-library-path" xreflabel="dynamic_library_path">
|
|
<term><varname>dynamic_library_path</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>dynamic_library_path</> configuration parameter</primary>
|
|
</indexterm>
|
|
<indexterm><primary>dynamic loading</></>
|
|
<listitem>
|
|
<para>
|
|
If a dynamically loadable module needs to be opened and the
|
|
file name specified in the <command>CREATE FUNCTION</command> or
|
|
<command>LOAD</command> command
|
|
does not have a directory component (i.e. the
|
|
name does not contain a slash), the system will search this
|
|
path for the required file.
|
|
</para>
|
|
|
|
<para>
|
|
The value for <varname>dynamic_library_path</varname> has to be a
|
|
list of absolute directory paths separated by colons (or semi-colons
|
|
on Windows). If a list element starts
|
|
with the special string <literal>$libdir</literal>, the
|
|
compiled-in <productname>PostgreSQL</productname> package
|
|
library directory is substituted for <literal>$libdir</literal>. This
|
|
is where the modules provided by the standard
|
|
<productname>PostgreSQL</productname> distribution are installed.
|
|
(Use <literal>pg_config --pkglibdir</literal> to find out the name of
|
|
this directory.) For example:
|
|
<programlisting>
|
|
dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir'
|
|
</programlisting>
|
|
or, in a Windows environment:
|
|
<programlisting>
|
|
dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
|
|
</programlisting>
|
|
</para>
|
|
|
|
<para>
|
|
The default value for this parameter is
|
|
<literal>'$libdir'</literal>. If the value is set to an empty
|
|
string, the automatic path search is turned off.
|
|
</para>
|
|
|
|
<para>
|
|
This parameter can be changed at run time by superusers, but a
|
|
setting done that way will only persist until the end of the
|
|
client connection, so this method should be reserved for
|
|
development purposes. The recommended way to set this parameter
|
|
is in the <filename>postgresql.conf</filename> configuration
|
|
file.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
</sect1>
|
|
|
|
<sect1 id="runtime-config-locks">
|
|
<title>Lock Management</title>
|
|
|
|
<variablelist>
|
|
|
|
<varlistentry id="guc-deadlock-timeout" xreflabel="deadlock_timeout">
|
|
<indexterm>
|
|
<primary>deadlock</primary>
|
|
<secondary>timeout during</secondary>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary>timeout</primary>
|
|
<secondary>deadlock</secondary>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary><varname>deadlock_timeout</> configuration parameter</primary>
|
|
</indexterm>
|
|
|
|
<term><varname>deadlock_timeout</varname> (<type>integer</type>)</term>
|
|
<listitem>
|
|
<para>
|
|
This is the amount of time, in milliseconds, to wait on a lock
|
|
before checking to see if there is a deadlock condition. The
|
|
check for deadlock is relatively slow, so the server doesn't run
|
|
it every time it waits for a lock. We (optimistically?) assume
|
|
that deadlocks are not common in production applications and
|
|
just wait on the lock for a while before starting the check for a
|
|
deadlock. Increasing this value reduces the amount of time
|
|
wasted in needless deadlock checks, but slows down reporting of
|
|
real deadlock errors. The default is 1000 (i.e., one second),
|
|
which is probably about the smallest value you would want in
|
|
practice. On a heavily loaded server you might want to raise it.
|
|
Ideally the setting should exceed your typical transaction time,
|
|
so as to improve the odds that a lock will be released before
|
|
the waiter decides to check for deadlock.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-max-locks-per-transaction" xreflabel="max_locks_per_transaction">
|
|
<term><varname>max_locks_per_transaction</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>max_locks_per_transaction</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
The shared lock table is created with room to describe locks on
|
|
<varname>max_locks_per_transaction</varname> *
|
|
(<xref linkend="guc-max-connections"> +
|
|
<xref linkend="guc-max-prepared-transactions">) objects;
|
|
hence, no more than this many distinct objects can
|
|
be locked at any one time. (Thus, this parameter's name may be
|
|
confusing: it is not a hard limit on the number of locks taken
|
|
by any one transaction, but rather a maximum average value.)
|
|
The default, 64, has historically
|
|
proven sufficient, but you might need to raise this value if you
|
|
have clients that touch many different tables in a single
|
|
transaction. This option can only be set at server start.
|
|
</para>
|
|
|
|
<para>
|
|
Increasing this parameter may cause <productname>PostgreSQL</>
|
|
to request more <systemitem class="osname">System V</> shared
|
|
memory than your operating system's default configuration
|
|
allows. See <xref linkend="sysvipc"> for information on how to
|
|
adjust those parameters, if necessary.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect1>
|
|
|
|
<sect1 id="runtime-config-compatible">
|
|
<title>Version and Platform Compatibility</title>
|
|
|
|
<sect2 id="runtime-config-compatible-version">
|
|
<title>Previous PostgreSQL Versions</title>
|
|
<variablelist>
|
|
|
|
<varlistentry id="guc-add-missing-from" xreflabel="add_missing_from">
|
|
<term><varname>add_missing_from</varname> (<type>boolean</type>)</term>
|
|
<indexterm><primary>FROM</><secondary>missing</></>
|
|
<indexterm>
|
|
<primary><varname>add_missing_from</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
When on, tables that are referenced by a query will be
|
|
automatically added to the <literal>FROM</> clause if not
|
|
already present. This behavior does not comply with the SQL
|
|
standard and many people dislike it because it can mask mistakes
|
|
(such as referencing a table where you should have referenced
|
|
its alias). The default is <literal>off</>. This variable can be
|
|
enabled for compatibility with releases of
|
|
<productname>PostgreSQL</> prior to 8.1, where this behavior was
|
|
allowed by default.
|
|
</para>
|
|
|
|
<para>
|
|
Note that even when this variable is enabled, a warning
|
|
message will be emitted for each implicit <literal>FROM</>
|
|
entry referenced by a query. Users are encouraged to update
|
|
their applications to not rely on this behavior, by adding all
|
|
tables referenced by a query to the query's <literal>FROM</>
|
|
clause (or its <literal>USING</> clause in the case of
|
|
<command>DELETE</>).
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-regex-flavor" xreflabel="regex_flavor">
|
|
<term><varname>regex_flavor</varname> (<type>string</type>)</term>
|
|
<indexterm><primary>regular expressions</></>
|
|
<indexterm>
|
|
<primary><varname>regex_flavor</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
The regular expression <quote>flavor</> can be set to
|
|
<literal>advanced</>, <literal>extended</>, or <literal>basic</>.
|
|
The default is <literal>advanced</>. The <literal>extended</>
|
|
setting may be useful for exact backwards compatibility with
|
|
pre-7.4 releases of <productname>PostgreSQL</>. See
|
|
<xref linkend="posix-syntax-details"> for details.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-sql-inheritance" xreflabel="sql_inheritance">
|
|
<term><varname>sql_inheritance</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>sql_inheritance</> configuration parameter</primary>
|
|
</indexterm>
|
|
<indexterm><primary>inheritance</></>
|
|
<listitem>
|
|
<para>
|
|
This controls the inheritance semantics, in particular whether
|
|
subtables are included by various commands by default. They were
|
|
not included in versions prior to 7.1. If you need the old
|
|
behavior you can set this variable to <literal>off</>, but in
|
|
the long run you are encouraged to change your applications to
|
|
use the <literal>ONLY</literal> key word to exclude subtables.
|
|
See <xref linkend="ddl-inherit"> for more information about
|
|
inheritance.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-default-with-oids" xreflabel="default_with_oids">
|
|
<term><varname>default_with_oids</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>default_with_oids</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
This controls whether <command>CREATE TABLE</command> and
|
|
<command>CREATE TABLE AS</command> include an OID column in
|
|
newly-created tables, if neither <literal>WITH OIDS</literal>
|
|
nor <literal>WITHOUT OIDS</literal> is specified. It also
|
|
determines whether OIDs will be included in tables created by
|
|
<command>SELECT INTO</command>. In <productname>PostgreSQL</>
|
|
8.1 <varname>default_with_oids</> is disabled by default; in
|
|
prior versions of <productname>PostgreSQL</productname>, it
|
|
was on by default.
|
|
</para>
|
|
|
|
<para>
|
|
The use of OIDs in user tables is considered deprecated, so
|
|
most installations should leave this variable disabled.
|
|
Applications that require OIDs for a particular table should
|
|
specify <literal>WITH OIDS</literal> when creating the
|
|
table. This variable can be enabled for compatibility with old
|
|
applications that do not follow this behavior.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-escape-string-warning" xreflabel="escape_string_warning">
|
|
<term><varname>escape_string_warning</varname> (<type>boolean</type>)</term>
|
|
<indexterm><primary>strings</><secondary>escape</></>
|
|
<indexterm>
|
|
<primary><varname>escape_string_warning</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
When on, a warning is issued if a backslash (<literal>\</>)
|
|
appears in an ordinary string literal (<literal>'...'</>
|
|
syntax). The default is <literal>off</>.
|
|
</para>
|
|
<para>
|
|
Escape string syntax (<literal>E'...'</>) should be used for
|
|
escapes, because in future versions of
|
|
<productname>PostgreSQL</productname> ordinary strings will have
|
|
the standard-conforming behavior of treating backslashes
|
|
literally.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
<sect2 id="runtime-config-compatible-clients">
|
|
<title>Platform and Client Compatibility</title>
|
|
<variablelist>
|
|
|
|
<varlistentry id="guc-transform-null-equals" xreflabel="transform_null_equals">
|
|
<term><varname>transform_null_equals</varname> (<type>boolean</type>)</term>
|
|
<indexterm><primary>IS NULL</></>
|
|
<indexterm>
|
|
<primary><varname>transform_null_equals</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
When on, expressions of the form <literal><replaceable>expr</> =
|
|
NULL</literal> (or <literal>NULL =
|
|
<replaceable>expr</></literal>) are treated as
|
|
<literal><replaceable>expr</> IS NULL</literal>, that is, they
|
|
return true if <replaceable>expr</> evaluates to the null value,
|
|
and false otherwise. The correct SQL-spec-compliant behavior of
|
|
<literal><replaceable>expr</> = NULL</literal> is to always
|
|
return null (unknown). Therefore this option defaults to
|
|
<literal>off</>.
|
|
</para>
|
|
|
|
<para>
|
|
However, filtered forms in <productname>Microsoft
|
|
Access</productname> generate queries that appear to use
|
|
<literal><replaceable>expr</> = NULL</literal> to test for
|
|
null values, so if you use that interface to access the database you
|
|
might want to turn this option on. Since expressions of the
|
|
form <literal><replaceable>expr</> = NULL</literal> always
|
|
return the null value (using the correct interpretation) they are not
|
|
very useful and do not appear often in normal applications, so
|
|
this option does little harm in practice. But new users are
|
|
frequently confused about the semantics of expressions
|
|
involving null values, so this option is not on by default.
|
|
</para>
|
|
|
|
<para>
|
|
Note that this option only affects the exact form <literal>= NULL</>,
|
|
not other comparison operators or other expressions
|
|
that are computationally equivalent to some expression
|
|
involving the equals operator (such as <literal>IN</literal>).
|
|
Thus, this option is not a general fix for bad programming.
|
|
</para>
|
|
|
|
<para>
|
|
Refer to <xref linkend="functions-comparison"> for related information.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect2>
|
|
</sect1>
|
|
|
|
<sect1 id="runtime-config-preset">
|
|
<title>Preset Options</title>
|
|
|
|
<para>
|
|
The following <quote>parameters</> are read-only, and are determined
|
|
when <productname>PostgreSQL</productname> is compiled or when it is
|
|
installed. As such, they have been excluded from the sample
|
|
<filename>postgresql.conf</> file. These options report
|
|
various aspects of <productname>PostgreSQL</productname> behavior
|
|
that may be of interest to certain applications, particularly
|
|
administrative front-ends.
|
|
</para>
|
|
|
|
<variablelist>
|
|
|
|
<varlistentry id="guc-block-size" xreflabel="block_size">
|
|
<term><varname>block_size</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>block_size</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Reports the size of a disk block. It is determined by the value
|
|
of <literal>BLCKSZ</> when building the server. The default
|
|
value is 8192 bytes. The meaning of some configuration
|
|
variables (such as <xref linkend="guc-shared-buffers">) is
|
|
influenced by <varname>block_size</varname>. See <xref
|
|
linkend="runtime-config-resource"> for information.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-integer-datetimes" xreflabel="integer_datetimes">
|
|
<term><varname>integer_datetimes</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>integer_datetimes</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Reports whether <productname>PostgreSQL</productname> was built
|
|
with support for 64-bit-integer dates and times. It is set by
|
|
configuring with <literal>--enable-integer-datetimes</literal>
|
|
when building <productname>PostgreSQL</productname>. The
|
|
default value is <literal>off</literal>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-lc-collate" xreflabel="lc_collate">
|
|
<term><varname>lc_collate</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>lc_collate</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Reports the locale in which sorting of textual data is done.
|
|
See <xref linkend="locale"> for more information.
|
|
The value is determined when the database cluster is initialized.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-lc-ctype" xreflabel="lc_ctype">
|
|
<term><varname>lc_ctype</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>lc_ctype</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Reports the locale that determines character classifications.
|
|
See <xref linkend="locale"> for more information.
|
|
The value is determined when the database cluster is initialized.
|
|
Ordinarily this will be the same as <varname>lc_collate</varname>,
|
|
but for special applications it might be set differently.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-max-function-args" xreflabel="max_function_args">
|
|
<term><varname>max_function_args</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>max_function_args</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Reports the maximum number of function arguments. It is determined by
|
|
the value of <literal>FUNC_MAX_ARGS</> when building the server. The
|
|
default value is 100.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-max-identifier-length" xreflabel="max_identifier_length">
|
|
<term><varname>max_identifier_length</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>max_identifier_length</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Reports the maximum identifier length. It is determined as one
|
|
less than the value of <literal>NAMEDATALEN</> when building
|
|
the server. The default value of <literal>NAMEDATALEN</> is
|
|
64; therefore the default
|
|
<varname>max_identifier_length</varname> is 63.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-max-index-keys" xreflabel="max_index_keys">
|
|
<term><varname>max_index_keys</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>max_index_keys</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Reports the maximum number of index keys. It is determined by
|
|
the value of <literal>INDEX_MAX_KEYS</> when building the server. The
|
|
default value is 32.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-server-encoding" xreflabel="server_encoding">
|
|
<term><varname>server_encoding</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>server_encoding</> configuration parameter</primary>
|
|
</indexterm>
|
|
<indexterm><primary>character set</></>
|
|
<listitem>
|
|
<para>
|
|
Reports the database encoding (character set).
|
|
It is determined when the database is created. Ordinarily,
|
|
clients need only be concerned with the value of <xref
|
|
linkend="guc-client-encoding">.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-server-version" xreflabel="server_version">
|
|
<term><varname>server_version</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>server_version</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Reports the version number of the server. It is determined by the
|
|
value of <literal>PG_VERSION</> when building the server.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-standard-conforming-strings" xreflabel="standard_conforming_strings">
|
|
<term><varname>standard_conforming_strings</varname> (<type>boolean</type>)</term>
|
|
<indexterm><primary>strings</><secondary>escape</></>
|
|
<indexterm>
|
|
<primary><varname>standard_conforming_strings</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Reports whether ordinary string literals
|
|
(<literal>'...'</>) treat backslashes literally, as specified in
|
|
the SQL standard. The value is currently always <literal>off</>,
|
|
indicating that backslashes are treated as escapes. It is planned
|
|
that this will change to <literal>on</> in a future
|
|
<productname>PostgreSQL</productname> release when string literal
|
|
syntax changes to meet the standard. Applications may check this
|
|
parameter to determine how string literals will be processed.
|
|
The presence of this parameter can also be taken as an indication
|
|
that the escape string syntax (<literal>E'...'</>) is supported.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</sect1>
|
|
|
|
<sect1 id="runtime-config-custom">
|
|
<title>Customized Options</title>
|
|
|
|
<para>
|
|
This feature was designed to allow options not normally known to
|
|
<productname>PostgreSQL</productname> to be added by add-on modules
|
|
(such as procedural languages). This allows add-on modules to be
|
|
configured in the standard ways.
|
|
</para>
|
|
|
|
<variablelist>
|
|
|
|
<varlistentry id="guc-custom-variable-classes" xreflabel="custom_variable_classes">
|
|
<term><varname>custom_variable_classes</varname> (<type>string</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>custom_variable_classes</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
This variable specifies one or several class names to be used for
|
|
custom variables, in the form of a comma-separated list. A custom
|
|
variable is a variable not normally known
|
|
to <productname>PostgreSQL</productname> proper but used by some
|
|
add-on module. Such variables must have names consisting of a class
|
|
name, a dot, and a variable name. <varname>custom_variable_classes</>
|
|
specifies all the class names in use in a particular installation.
|
|
This option can only be set at server start or in the
|
|
<filename>postgresql.conf</filename> configuration file.
|
|
</para>
|
|
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
|
|
<para>
|
|
The difficulty with setting custom variables in
|
|
<filename>postgresql.conf</> is that the file must be read before add-on
|
|
modules have been loaded, and so custom variables would ordinarily be
|
|
rejected as unknown. When <varname>custom_variable_classes</> is set,
|
|
the server will accept definitions of arbitrary variables within each
|
|
specified class. These variables will be treated as placeholders and
|
|
will have no function until the module that defines them is loaded. When a
|
|
module for a specific class is loaded, it will add the proper variable
|
|
definitions for its class name, convert any placeholder
|
|
values according to those definitions, and issue warnings for any
|
|
placeholders of its class that remain (which presumably would be
|
|
misspelled configuration variables).
|
|
</para>
|
|
|
|
<para>
|
|
Here is an example of what <filename>postgresql.conf</> might contain
|
|
when using custom variables:
|
|
|
|
<programlisting>
|
|
custom_variable_classes = 'plr,plperl'
|
|
plr.path = '/usr/lib/R'
|
|
plperl.use_strict = true
|
|
plruby.use_strict = true # generates error: unknown class name
|
|
</programlisting>
|
|
</para>
|
|
</sect1>
|
|
|
|
<sect1 id="runtime-config-developer">
|
|
<title>Developer Options</title>
|
|
|
|
<para>
|
|
The following options are intended for work on the
|
|
<productname>PostgreSQL</productname> source, 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.
|
|
As such, they have been excluded from the sample
|
|
<filename>postgresql.conf</> file. Note that many of these
|
|
options require special source compilation flags to work at all.
|
|
</para>
|
|
|
|
<variablelist>
|
|
<varlistentry id="guc-debug-assertions" xreflabel="debug_assertions">
|
|
<term><varname>debug_assertions</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>debug_assertions</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Turns on various assertion checks. This is a debugging aid. If
|
|
you are experiencing strange problems or crashes you might want
|
|
to turn this on, as it might expose programming mistakes. To use
|
|
this option, the macro <symbol>USE_ASSERT_CHECKING</symbol>
|
|
must be defined when <productname>PostgreSQL</productname> is
|
|
built (accomplished by the <command>configure</command> option
|
|
<option>--enable-cassert</option>). Note that
|
|
<varname>debug_assertions</varname> defaults to <literal>on</>
|
|
if <productname>PostgreSQL</productname> has been built with
|
|
assertions enabled.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-pre-auth-delay" xreflabel="pre_auth_delay">
|
|
<term><varname>pre_auth_delay</varname> (<type>integer</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>pre_auth_delay</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
If nonzero, a delay of this many seconds occurs just after a new
|
|
server process is forked, before it conducts the authentication
|
|
process. This is intended to give an opportunity to attach to the
|
|
server process with a debugger to trace down misbehavior in
|
|
authentication.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-trace-notify" xreflabel="trace_notify">
|
|
<term><varname>trace_notify</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>trace_notify</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Generates a great amount of debugging output for the
|
|
<command>LISTEN</command> and <command>NOTIFY</command>
|
|
commands. <xref linkend="guc-client-min-messages"> or
|
|
<xref linkend="guc-log-min-messages"> must be
|
|
<literal>DEBUG1</literal> or lower to send this output to the
|
|
client or server log, respectively.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-trace-sort" xreflabel="trace_sort">
|
|
<term><varname>trace_sort</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>trace_sort</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
If on, emit information about resource usage during sort operations.
|
|
This option is only available if the <symbol>TRACE_SORT</symbol> macro
|
|
was defined when <productname>PostgreSQL</productname> was compiled.
|
|
(However, <symbol>TRACE_SORT</symbol> is currently defined by default.)
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>trace_locks</varname> (<type>boolean</type>)</term>
|
|
<term><varname>trace_lwlocks</varname> (<type>boolean</type>)</term>
|
|
<term><varname>trace_userlocks</varname> (<type>boolean</type>)</term>
|
|
<term><varname>trace_lock_oidmin</varname> (<type>boolean</type>)</term>
|
|
<term><varname>trace_lock_table</varname> (<type>boolean</type>)</term>
|
|
<term><varname>debug_deadlocks</varname> (<type>boolean</type>)</term>
|
|
<term><varname>log_btree_build_stats</varname> (<type>boolean</type>)</term>
|
|
<listitem>
|
|
<para>
|
|
Various other code tracing and debugging options.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-wal-debug" xreflabel="wal_debug">
|
|
<term><varname>wal_debug</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>wal_debug</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
If on, emit WAL-related debugging output. This option is
|
|
only available if the <symbol>WAL_DEBUG</symbol> macro was
|
|
defined when <productname>PostgreSQL</productname> was
|
|
compiled.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="guc-zero-damaged-pages" xreflabel="zero_damaged_pages">
|
|
<term><varname>zero_damaged_pages</varname> (<type>boolean</type>)</term>
|
|
<indexterm>
|
|
<primary><varname>zero_damaged_pages</> configuration parameter</primary>
|
|
</indexterm>
|
|
<listitem>
|
|
<para>
|
|
Detection of a damaged page header normally causes
|
|
<productname>PostgreSQL</> to report an error, aborting the current
|
|
command. Setting <varname>zero_damaged_pages</> to on causes
|
|
the system to instead report a warning, zero out the damaged page,
|
|
and continue processing. This behavior <emphasis>will destroy data</>,
|
|
namely all the rows on the damaged page. But it allows you to get
|
|
past the error and retrieve rows from any undamaged pages that may
|
|
be present in the table. So it is useful for recovering data if
|
|
corruption has occurred due to hardware or software error. You should
|
|
generally not set this on until you have given up hope of recovering
|
|
data from the damaged page(s) of a table. The
|
|
default setting is <literal>off</>, and it can only be changed
|
|
by a superuser.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</sect1>
|
|
<sect1 id="runtime-config-short">
|
|
<title>Short Options</title>
|
|
|
|
<para>
|
|
For convenience there are also single letter command-line option switches
|
|
available for some parameters. They are described in <xref
|
|
linkend="runtime-config-short-table">.
|
|
</para>
|
|
|
|
<table id="runtime-config-short-table">
|
|
<title>Short option key</title>
|
|
<tgroup cols="2">
|
|
<thead>
|
|
<row>
|
|
<entry>Short option</entry>
|
|
<entry>Equivalent</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><option>-B <replaceable>x</replaceable></option></entry>
|
|
<entry><literal>shared_buffers = <replaceable>x</replaceable></></entry>
|
|
</row>
|
|
<row>
|
|
<entry><option>-d <replaceable>x</replaceable></option></entry>
|
|
<entry><literal>log_min_messages = DEBUG<replaceable>x</replaceable></></entry>
|
|
</row>
|
|
<row>
|
|
<entry><option>-F</option></entry>
|
|
<entry><literal>fsync = off</></entry>
|
|
</row>
|
|
<row>
|
|
<entry><option>-h <replaceable>x</replaceable></option></entry>
|
|
<entry><literal>listen_addresses = <replaceable>x</replaceable></></entry>
|
|
</row>
|
|
<row>
|
|
<entry><option>-i</option></entry>
|
|
<entry><literal>listen_addresses = '*'</></entry>
|
|
</row>
|
|
<row>
|
|
<entry><option>-k <replaceable>x</replaceable></option></entry>
|
|
<entry><literal>unix_socket_directory = <replaceable>x</replaceable></></entry>
|
|
</row>
|
|
<row>
|
|
<entry><option>-l</option></entry>
|
|
<entry><literal>ssl = on</></entry>
|
|
</row>
|
|
<row>
|
|
<entry><option>-N <replaceable>x</replaceable></option></entry>
|
|
<entry><literal>max_connections = <replaceable>x</replaceable></></entry>
|
|
</row>
|
|
<row>
|
|
<entry><option>-p <replaceable>x</replaceable></option></entry>
|
|
<entry><literal>port = <replaceable>x</replaceable></></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry>
|
|
<option>-fb</option>, <option>-fh</option>, <option>-fi</option>,
|
|
<option>-fm</option>, <option>-fn</option>,
|
|
<option>-fs</option>, <option>-ft</option><footnote
|
|
id="fn.runtime-config-short">
|
|
<para>
|
|
For historical reasons, these options must be passed to
|
|
the individual server process via the <option>-o</option>
|
|
<command>postmaster</command> option, for example,
|
|
<screen>
|
|
$ <userinput>postmaster -o '-S 1024 -s'</userinput>
|
|
</screen>
|
|
or via <envar>PGOPTIONS</envar> from the client side, as
|
|
explained above.
|
|
</para>
|
|
</footnote>
|
|
</entry>
|
|
<entry>
|
|
<literal>enable_bitmapscan = off</>,
|
|
<literal>enable_hashjoin = off</>,
|
|
<literal>enable_indexscan = off</>,
|
|
<literal>enable_mergejoin = off</>,
|
|
<literal>enable_nestloop = off</>,
|
|
<literal>enable_seqscan = off</>,
|
|
<literal>enable_tidscan = off</>
|
|
</entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><option>-s</option><footnoteref linkend="fn.runtime-config-short"></entry>
|
|
<entry><literal>log_statement_stats = on</></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><option>-S <replaceable>x</replaceable></option><footnoteref linkend="fn.runtime-config-short">
|
|
</entry>
|
|
<entry><literal>work_mem = <replaceable>x</replaceable></></entry>
|
|
</row>
|
|
|
|
<row>
|
|
<entry><option>-tpa</option>, <option>-tpl</option>, <option>-te</option><footnoteref linkend="fn.runtime-config-short"></entry>
|
|
<entry><literal>log_parser_stats = on</>,
|
|
<literal>log_planner_stats = on</>,
|
|
<literal>log_executor_stats = on</></entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
</sect1>
|
|
</chapter>
|
|
|
|
<!-- 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:
|
|
-->
|