From 159dcdc121523d10aa6bf1030c35052a3a8c5e2b Mon Sep 17 00:00:00 2001
From: Nathan Bossart <nathan@postgresql.org>
Date: Wed, 18 Jun 2025 11:08:26 -0500
Subject: [PATCH v7 5/5] add flush_unlogged option to checkpoint command

---
 doc/src/sgml/ref/checkpoint.sgml      | 26 ++++++++++++++++++++++++++
 src/backend/postmaster/checkpointer.c |  4 ++++
 src/bin/psql/tab-complete.in.c        |  2 +-
 src/test/regress/expected/stats.out   |  2 +-
 src/test/regress/sql/stats.sql        |  2 +-
 5 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/doc/src/sgml/ref/checkpoint.sgml b/doc/src/sgml/ref/checkpoint.sgml
index d66aa967afc..8054de78a9b 100644
--- a/doc/src/sgml/ref/checkpoint.sgml
+++ b/doc/src/sgml/ref/checkpoint.sgml
@@ -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>
@@ -75,6 +76,17 @@ CHECKPOINT [ ( option [, ...] ) ]
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>FLUSH_UNLOGGED</literal></term>
+    <listitem>
+     <para>
+      Normally, <command>CHECKPOINT</command> does not flush data files for
+      unlogged relations.  This option, which is disabled by default, enables
+      flushing unlogged relations.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>MODE</literal></term>
     <listitem>
@@ -92,6 +104,20 @@ 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>
 
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index 723322e3e03..a3e4e70ad66 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -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\"", opt->defname),
 						 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));
 }
 
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 177615aff27..a3f46a205ec 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -3137,7 +3137,7 @@ 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");
 	}
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 02cdc3cbcf6..6ebcc292834 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -930,7 +930,7 @@ DROP TABLE test_stats_temp;
 -- While at it, test checkpoint options.  Note that we don't test MODE SPREAD
 -- because it would prolong the test.
 CHECKPOINT (MODE FAST);
-CHECKPOINT;
+CHECKPOINT (FLUSH_UNLOGGED);
 SELECT num_requested > :rqst_ckpts_before FROM pg_stat_checkpointer;
  ?column? 
 ----------
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 5ed71d7054e..dab19918056 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -443,7 +443,7 @@ DROP TABLE test_stats_temp;
 -- While at it, test checkpoint options.  Note that we don't test MODE SPREAD
 -- because it would prolong the test.
 CHECKPOINT (MODE FAST);
-CHECKPOINT;
+CHECKPOINT (FLUSH_UNLOGGED);
 
 SELECT num_requested > :rqst_ckpts_before FROM pg_stat_checkpointer;
 SELECT wal_bytes > :wal_bytes_before FROM pg_stat_wal;
-- 
2.39.5 (Apple Git-154)