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Add MODE option to CHECKPOINT command.

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This option may be set to FAST (the default) to request the
checkpoint be completed as fast as possible, or SPREAD to request
the checkpoint be spread over a longer interval (based on the
checkpoint-related configuration parameters).  Note that the server
may consolidate the options for concurrently requested checkpoints.
For example, if one session requests a "fast" checkpoint and
another requests a "spread" checkpoint, the server may perform one
"fast" checkpoint.

Author: Christoph Berg <myon@debian.org>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Fujii Masao <masao.fujii@oss.nttdata.com>
Reviewed-by: Laurenz Albe <laurenz.albe@cybertec.at>
Reviewed-by: Dilip Kumar <dilipbalaut@gmail.com>
Discussion: https://postgr.es/m/aDnaKTEf-0dLiEfz%40msg.df7cb.de
This commit is contained in:
Nathan Bossart
2025-07-11 11:51:25 -05:00
parent a4f126516e
commit 2f698d7f4b
5 changed files with 79 additions and 12 deletions
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35
doc/src/sgml/ref/checkpoint.sgml
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@ -24,6 +24,8 @@ PostgreSQL documentation
CHECKPOINT [ ( option [, ...] ) ]
<phrase>where <replaceable class="parameter">option</replaceable> can be one of:</phrase>
MODE { FAST | SPREAD }
</synopsis>
</refsynopsisdiv>
@ -39,14 +41,24 @@ CHECKPOINT [ ( option [, ...] ) ]
</para>
<para>
The <command>CHECKPOINT</command> command forces a fast
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"/>)
@ -63,8 +75,25 @@ CHECKPOINT [ ( option [, ...] ) ]
<refsect1>
<title>Parameters</title>
<para>
</para>
<variablelist>
<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>
</variablelist>
</refsect1>
<refsect1>