v8-0001-Log-checkpoint-request-flags-in-checkpoint-comple.patch

From d9f3cbf8502124550f4e5378f17d3a4b3c449c82 Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Tue, 17 Feb 2026 12:27:34 +0900
Subject: [PATCH v8] Log checkpoint request flags in checkpoint completion
 messages.

Checkpoint completion log messages include more detail than checkpoint
start messages, but previously omitted the checkpoint request flags,
which were only logged at checkpoint start. As a result, users had to
correlate completion messages with earlier start messages to see
the full context.

This commit includes the checkpoint request flags in the checkpoint
completion log message as well. This duplicates some information,
but makes the completion message self-contained and easier to interpret.

Author: Soumya S Murali <soumyamurali.work@gmail.com>
Reviewed-by: Michael Banck <mbanck@gmx.net>
Reviewed-by: Yuan Li <carol.li2025@outlook.com>
Reviewed-by: Fujii Masao <masao.fujii@gmail.com>
Discussion: https://postgr.es/m/CAMtXxw9tPwV=NBv5S9GZXMSKPeKv5f9hRhSjZ8__oLsoS5jcuA@mail.gmail.com
---
 src/backend/access/transam/xlog.c | 60 ++++++++++++++++++-------------
 1 file changed, 35 insertions(+), 25 deletions(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 13ec6225b85..13cce9b49f1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6768,6 +6768,28 @@ ShutdownXLOG(int code, Datum arg)
 	}
 }
 
+/*
+ * Format checkpoint request flags as a space-separated string for
+ * log messages.
+ */
+static const char *
+CheckpointFlagsString(int flags)
+{
+	static char buf[128];
+
+	snprintf(buf, sizeof(buf), "%s%s%s%s%s%s%s%s",
+			 (flags & CHECKPOINT_IS_SHUTDOWN) ? " shutdown" : "",
+			 (flags & CHECKPOINT_END_OF_RECOVERY) ? " end-of-recovery" : "",
+			 (flags & CHECKPOINT_FAST) ? " fast" : "",
+			 (flags & CHECKPOINT_FORCE) ? " force" : "",
+			 (flags & CHECKPOINT_WAIT) ? " wait" : "",
+			 (flags & CHECKPOINT_CAUSE_XLOG) ? " wal" : "",
+			 (flags & CHECKPOINT_CAUSE_TIME) ? " time" : "",
+			 (flags & CHECKPOINT_FLUSH_UNLOGGED) ? " flush-unlogged" : "");
+
+	return buf;
+}
+
 /*
  * Log start of a checkpoint.
  */
@@ -6776,35 +6798,21 @@ LogCheckpointStart(int flags, bool restartpoint)
 {
 	if (restartpoint)
 		ereport(LOG,
-		/* translator: the placeholders show checkpoint options */
-				(errmsg("restartpoint starting:%s%s%s%s%s%s%s%s",
-						(flags & CHECKPOINT_IS_SHUTDOWN) ? " shutdown" : "",
-						(flags & CHECKPOINT_END_OF_RECOVERY) ? " end-of-recovery" : "",
-						(flags & CHECKPOINT_FAST) ? " fast" : "",
-						(flags & CHECKPOINT_FORCE) ? " force" : "",
-						(flags & CHECKPOINT_WAIT) ? " wait" : "",
-						(flags & CHECKPOINT_CAUSE_XLOG) ? " wal" : "",
-						(flags & CHECKPOINT_CAUSE_TIME) ? " time" : "",
-						(flags & CHECKPOINT_FLUSH_UNLOGGED) ? " flush-unlogged" : "")));
+		/* translator: the placeholder shows checkpoint options */
+				(errmsg("restartpoint starting:%s",
+						CheckpointFlagsString(flags))));
 	else
 		ereport(LOG,
-		/* translator: the placeholders show checkpoint options */
-				(errmsg("checkpoint starting:%s%s%s%s%s%s%s%s",
-						(flags & CHECKPOINT_IS_SHUTDOWN) ? " shutdown" : "",
-						(flags & CHECKPOINT_END_OF_RECOVERY) ? " end-of-recovery" : "",
-						(flags & CHECKPOINT_FAST) ? " fast" : "",
-						(flags & CHECKPOINT_FORCE) ? " force" : "",
-						(flags & CHECKPOINT_WAIT) ? " wait" : "",
-						(flags & CHECKPOINT_CAUSE_XLOG) ? " wal" : "",
-						(flags & CHECKPOINT_CAUSE_TIME) ? " time" : "",
-						(flags & CHECKPOINT_FLUSH_UNLOGGED) ? " flush-unlogged" : "")));
+		/* translator: the placeholder shows checkpoint options */
+				(errmsg("checkpoint starting:%s",
+						CheckpointFlagsString(flags))));
 }
 
 /*
  * Log end of a checkpoint.
  */
 static void
-LogCheckpointEnd(bool restartpoint)
+LogCheckpointEnd(bool restartpoint, int flags)
 {
 	long		write_msecs,
 				sync_msecs,
@@ -6854,12 +6862,13 @@ LogCheckpointEnd(bool restartpoint)
 	 */
 	if (restartpoint)
 		ereport(LOG,
-				(errmsg("restartpoint complete: wrote %d buffers (%.1f%%), "
+				(errmsg("restartpoint complete:%s: wrote %d buffers (%.1f%%), "
 						"wrote %d SLRU buffers; %d WAL file(s) added, "
 						"%d removed, %d recycled; write=%ld.%03d s, "
 						"sync=%ld.%03d s, total=%ld.%03d s; sync files=%d, "
 						"longest=%ld.%03d s, average=%ld.%03d s; distance=%d kB, "
 						"estimate=%d kB; lsn=%X/%08X, redo lsn=%X/%08X",
+						CheckpointFlagsString(flags),
 						CheckpointStats.ckpt_bufs_written,
 						(double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers,
 						CheckpointStats.ckpt_slru_written,
@@ -6878,12 +6887,13 @@ LogCheckpointEnd(bool restartpoint)
 						LSN_FORMAT_ARGS(ControlFile->checkPointCopy.redo))));
 	else
 		ereport(LOG,
-				(errmsg("checkpoint complete: wrote %d buffers (%.1f%%), "
+				(errmsg("checkpoint complete:%s: wrote %d buffers (%.1f%%), "
 						"wrote %d SLRU buffers; %d WAL file(s) added, "
 						"%d removed, %d recycled; write=%ld.%03d s, "
 						"sync=%ld.%03d s, total=%ld.%03d s; sync files=%d, "
 						"longest=%ld.%03d s, average=%ld.%03d s; distance=%d kB, "
 						"estimate=%d kB; lsn=%X/%08X, redo lsn=%X/%08X",
+						CheckpointFlagsString(flags),
 						CheckpointStats.ckpt_bufs_written,
 						(double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers,
 						CheckpointStats.ckpt_slru_written,
@@ -7480,7 +7490,7 @@ CreateCheckPoint(int flags)
 		TruncateSUBTRANS(GetOldestTransactionIdConsideredRunning());
 
 	/* Real work is done; log and update stats. */
-	LogCheckpointEnd(false);
+	LogCheckpointEnd(false, flags);
 
 	/* Reset the process title */
 	update_checkpoint_display(flags, false, true);
@@ -7951,7 +7961,7 @@ CreateRestartPoint(int flags)
 		TruncateSUBTRANS(GetOldestTransactionIdConsideredRunning());
 
 	/* Real work is done; log and update stats. */
-	LogCheckpointEnd(true);
+	LogCheckpointEnd(true, flags);
 
 	/* Reset the process title */
 	update_checkpoint_display(flags, true, true);
-- 
2.51.2