v2-1-Add-checkpoint-and-redo-LSN-to-LogCheckpointEnd-l.patch

From 999cfd53ce4e16ccfff94c0022cd80fe8ff84be5 Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Tue, 28 Dec 2021 02:45:51 +0000
Subject: [PATCH v2] Add checkpoint and redo LSN to LogCheckpointEnd log
 message

It is useful (for debugging purposes) if the checkpoint end message
has the checkpoint LSN and REDO LSN. 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 1e1fbe957f..26eb2a22f3 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -8920,11 +8920,14 @@ LogCheckpointEnd(bool restartpoint)
 
 	if (restartpoint)
 		ereport(LOG,
-				(errmsg("restartpoint complete: wrote %d buffers (%.1f%%); "
+				(errmsg("restartpoint complete: location=%X/%X, REDO start location=%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->checkPoint),
+						LSN_FORMAT_ARGS(ControlFile->checkPointCopy.redo),
 						CheckpointStats.ckpt_bufs_written,
 						(double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers,
 						CheckpointStats.ckpt_segs_added,
@@ -8940,11 +8943,14 @@ LogCheckpointEnd(bool restartpoint)
 						(int) (CheckPointDistanceEstimate / 1024.0))));
 	else
 		ereport(LOG,
-				(errmsg("checkpoint complete: wrote %d buffers (%.1f%%); "
+				(errmsg("checkpoint complete: location=%X/%X, REDO start location=%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->checkPoint),
+						LSN_FORMAT_ARGS(ControlFile->checkPointCopy.redo),
 						CheckpointStats.ckpt_bufs_written,
 						(double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers,
 						CheckpointStats.ckpt_segs_added,
-- 
2.25.1