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Add FLUSH_UNLOGGED option to CHECKPOINT command.

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This option, which is disabled by default, can be used to request
the checkpoint also flush dirty buffers of unlogged relations.  As
with the MODE option, the server may consolidate the options for
concurrently requested checkpoints.  For example, if one session
uses (FLUSH_UNLOGGED FALSE) and another uses (FLUSH_UNLOGGED TRUE),
the server may perform one checkpoint with FLUSH_UNLOGGED enabled.

Author: Christoph Berg <myon@debian.org>
Reviewed-by: Laurenz Albe <laurenz.albe@cybertec.at>
Reviewed-by: Fujii Masao <masao.fujii@oss.nttdata.com>
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 2f698d7f4b
commit 8d33fbacba
5 changed files with 35 additions and 5 deletions
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26
doc/src/sgml/ref/checkpoint.sgml
View File

@ -25,6 +25,7 @@ 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>
@ -76,6 +77,17 @@ CHECKPOINT [ ( option [, ...] ) ]
<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>
@ -93,6 +105,20 @@ CHECKPOINT [ ( option [, ...] ) ]
</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>

4
src/backend/postmaster/checkpointer.c
View File

@ -989,6 +989,7 @@ void
ExecCheckpoint(ParseState *pstate, CheckPointStmt *stmt)
{
bool fast = true;
bool unlogged = false;
foreach_ptr(DefElem, opt, stmt->options)
{
@ -1004,6 +1005,8 @@ ExecCheckpoint(ParseState *pstate, CheckPointStmt *stmt)
errmsg("unrecognized MODE option \"%s\"", mode),
parser_errposition(pstate, opt->location)));
}
else if (strcmp(opt->defname, "flush_unlogged") == 0)
unlogged = defGetBoolean(opt);
else
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
@ -1022,6 +1025,7 @@ ExecCheckpoint(ParseState *pstate, CheckPointStmt *stmt)
RequestCheckpoint(CHECKPOINT_WAIT |
(fast ? CHECKPOINT_FAST : 0) |
(unlogged ? CHECKPOINT_FLUSH_UNLOGGED : 0) |
(RecoveryInProgress() ? 0 : CHECKPOINT_FORCE));
}

2
src/bin/psql/tab-complete.in.c
View File

@ -3165,7 +3165,7 @@ match_previous_words(int pattern_id,
* one word, so the above test is correct.
*/
if (ends_with(prev_wd, '(') || ends_with(prev_wd, ','))
COMPLETE_WITH("MODE");
COMPLETE_WITH("MODE", "FLUSH_UNLOGGED");
else if (TailMatches("MODE"))
COMPLETE_WITH("FAST", "SPREAD");
}

4
src/test/regress/expected/stats.out
View File

@ -937,8 +937,8 @@ CHECKPOINT (MODE WRONG);
ERROR: unrecognized MODE option "wrong"
LINE 1: CHECKPOINT (MODE WRONG);
^
CHECKPOINT (MODE FAST);
CHECKPOINT;
CHECKPOINT (MODE FAST, FLUSH_UNLOGGED FALSE);
CHECKPOINT (FLUSH_UNLOGGED);
SELECT num_requested > :rqst_ckpts_before FROM pg_stat_checkpointer;
?column?
----------

4
src/test/regress/sql/stats.sql
View File

@ -444,8 +444,8 @@ DROP TABLE test_stats_temp;
-- because it would prolong the test.
CHECKPOINT (WRONG);
CHECKPOINT (MODE WRONG);
CHECKPOINT (MODE FAST);
CHECKPOINT;
CHECKPOINT (MODE FAST, FLUSH_UNLOGGED FALSE);
CHECKPOINT (FLUSH_UNLOGGED);
SELECT num_requested > :rqst_ckpts_before FROM pg_stat_checkpointer;
SELECT wal_bytes > :wal_bytes_before FROM pg_stat_wal;