v1-0002-doc-Clarify-CHECKPOINT-handling-of-unlogged-buffe.patch

From 8e18462c160a45ebf0cec535b6ab48c0fed942c4 Mon Sep 17 00:00:00 2001
From: "Chao Li (Evan)" <lic@highgo.com>
Date: Mon, 25 May 2026 14:30:41 +0800
Subject: [PATCH v1 2/2] doc: Clarify CHECKPOINT handling of unlogged buffers

The CHECKPOINT reference page still described checkpoints as flushing all
data files, which became misleading after adding the FLUSH_UNLOGGED
option. By default, manual checkpoints flush dirty buffers for permanent
relations but do not flush dirty buffers of unlogged relations.

Update the description to mention that exception and point readers to
FLUSH_UNLOGGED when they want unlogged buffers flushed too.

Author: Chao Li <lic@highgo.com>
---
 doc/src/sgml/ref/checkpoint.sgml | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/doc/src/sgml/ref/checkpoint.sgml b/doc/src/sgml/ref/checkpoint.sgml
index cd981cf2cab..a43a1913b41 100644
--- a/doc/src/sgml/ref/checkpoint.sgml
+++ b/doc/src/sgml/ref/checkpoint.sgml
@@ -35,8 +35,10 @@ CHECKPOINT [ ( option [, ...] ) ]
 
   <para>
    A checkpoint is a point in the write-ahead log sequence at which
-   all data files have been updated to reflect the information in the
-   log.  All data files will be flushed to disk.  Refer to
+   data files for permanent relations have been updated to reflect the
+   information in the log.  Those data files will be flushed to disk.
+   Dirty buffers of unlogged relations are normally not flushed unless
+   <literal>FLUSH_UNLOGGED</literal> is specified.  Refer to
    <xref linkend="wal-configuration"/> for more details about what happens
    during a checkpoint.
   </para>
-- 
2.50.1 (Apple Git-155)