v5-0001-Add-checkpoint-and-redo-LSN-to-LogCheckpointEnd-l.patch

From beafea457cd80266c6e517862ed819da7b3c8ec0 Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Mon, 31 Jan 2022 16:51:47 +0000
Subject: [PATCH v5] Add checkpoint and redo LSN to LogCheckpointEnd log
 message

It is useful (for debugging purposes) if the checkpoint end message
has the checkpoint LSN(end) and REDO LSN(start). It gives more
context while analyzing checkpoint-related issues. The pg_controldata
gives the last checkpoint LSN and REDO LSN, but having this info
alongside the log message helps analyze issues that happened
previously, connect the dots and identify the root cause.
---
 src/backend/access/transam/xlog.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index dfe2a0bcce..71a5239619 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -8919,11 +8919,14 @@ LogCheckpointEnd(bool restartpoint)
 
 	if (restartpoint)
 		ereport(LOG,
-				(errmsg("restartpoint complete: wrote %d buffers (%.1f%%); "
+				(errmsg("restartpoint complete: lsn=%X/%X, redo lsn=%X/%X; "
+						"wrote %d buffers (%.1f%%); "
 						"%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_FORMAT_ARGS(ControlFile->checkPointCopy.redo),
+						LSN_FORMAT_ARGS(ControlFile->checkPoint),
 						CheckpointStats.ckpt_bufs_written,
 						(double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers,
 						CheckpointStats.ckpt_segs_added,
@@ -8939,11 +8942,14 @@ LogCheckpointEnd(bool restartpoint)
 						(int) (CheckPointDistanceEstimate / 1024.0))));
 	else
 		ereport(LOG,
-				(errmsg("checkpoint complete: wrote %d buffers (%.1f%%); "
+				(errmsg("checkpoint complete: lsn=%X/%X, redo lsn=%X/%X; "
+						"wrote %d buffers (%.1f%%); "
 						"%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_FORMAT_ARGS(ControlFile->checkPointCopy.redo),
+						LSN_FORMAT_ARGS(ControlFile->checkPoint),
 						CheckpointStats.ckpt_bufs_written,
 						(double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers,
 						CheckpointStats.ckpt_segs_added,
-- 
2.25.1