diff options
Diffstat (limited to 'doc/src/sgml/ref')
| -rw-r--r-- | doc/src/sgml/ref/checkpoint.sgml | 68 | ||||
| -rw-r--r-- | doc/src/sgml/ref/pg_basebackup.sgml | 3 |
2 files changed, 68 insertions, 3 deletions
diff --git a/doc/src/sgml/ref/checkpoint.sgml b/doc/src/sgml/ref/checkpoint.sgml index db011a47d04..cd981cf2cab 100644 --- a/doc/src/sgml/ref/checkpoint.sgml +++ b/doc/src/sgml/ref/checkpoint.sgml @@ -21,7 +21,12 @@ PostgreSQL documentation <refsynopsisdiv> <synopsis> -CHECKPOINT +CHECKPOINT [ ( option [, ...] ) ] + +<phrase>where <replaceable class="parameter">option</replaceable> can be one of:</phrase> + + FLUSH_UNLOGGED [ <replaceable class="parameter">boolean</replaceable> ] + MODE { FAST | SPREAD } </synopsis> </refsynopsisdiv> @@ -37,15 +42,25 @@ CHECKPOINT </para> <para> - The <command>CHECKPOINT</command> command forces an immediate + By default, the <command>CHECKPOINT</command> command forces a fast checkpoint when the command is issued, without waiting for a regular checkpoint scheduled by the system (controlled by the settings in <xref linkend="runtime-config-wal-checkpoints"/>). + To request the checkpoint be spread over a longer interval, set the + <literal>MODE</literal> option to <literal>SPREAD</literal>. <command>CHECKPOINT</command> is not intended for use during normal operation. </para> <para> + The server may consolidate concurrently requested checkpoints. Such + consolidated requests will contain a combined set of options. For example, + if one session requests a fast checkpoint and another requests a spread + checkpoint, the server may combine those requests and perform one fast + checkpoint. + </para> + + <para> If executed during recovery, the <command>CHECKPOINT</command> command will force a restartpoint (see <xref linkend="wal-configuration"/>) rather than writing a new checkpoint. @@ -59,6 +74,55 @@ CHECKPOINT </refsect1> <refsect1> + <title>Parameters</title> + + <variablelist> + <varlistentry> + <term><literal>FLUSH_UNLOGGED</literal></term> + <listitem> + <para> + Normally, <command>CHECKPOINT</command> does not flush dirty buffers of + unlogged relations. This option, which is disabled by default, enables + flushing unlogged relations to disk. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>MODE</literal></term> + <listitem> + <para> + When set to <literal>FAST</literal>, which is the default, the requested + checkpoint will be completed as fast as possible, which may result in a + significantly higher rate of I/O during the checkpoint. + </para> + <para> + <literal>MODE</literal> can also be set to <literal>SPREAD</literal> to + request the checkpoint be spread over a longer interval (controlled via + the settings in <xref linkend="runtime-config-wal-checkpoints"/>), like a + regular checkpoint scheduled by the system. This can reduce the rate of + I/O during the checkpoint. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><replaceable class="parameter">boolean</replaceable></term> + <listitem> + <para> + Specifies whether the selected option should be turned on or off. + You can write <literal>TRUE</literal>, <literal>ON</literal>, or + <literal>1</literal> to enable the option, and <literal>FALSE</literal>, + <literal>OFF</literal>, or <literal>0</literal> to disable it. The + <replaceable class="parameter">boolean</replaceable> value can also + be omitted, in which case <literal>TRUE</literal> is assumed. + </para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> <title>Compatibility</title> <para> diff --git a/doc/src/sgml/ref/pg_basebackup.sgml b/doc/src/sgml/ref/pg_basebackup.sgml index 9659f76042c..fecee08b0a5 100644 --- a/doc/src/sgml/ref/pg_basebackup.sgml +++ b/doc/src/sgml/ref/pg_basebackup.sgml @@ -500,8 +500,9 @@ PostgreSQL documentation <term><option>--checkpoint={fast|spread}</option></term> <listitem> <para> - Sets checkpoint mode to fast (immediate) or spread (the default) + Sets checkpoint mode to fast or spread (see <xref linkend="backup-lowlevel-base-backup"/>). + The default is spread. </para> </listitem> </varlistentry> |