Hi, all
I've noticed an inconsistency in the LSN format printed by pg_waldump,
specifically concerning the lsn: and prev fields in the output.
$ pg_waldump /tmp/pgdata02/pg_wal/00000001000000000000000A 2>/dev/null
|grep 'AB10260'
rmgr: XLOG len (rec/tot): 114/ 114, tx: 0, lsn:
0/0AB10260, prev 0/0AB10228, desc: CHECKPOINT_SHUTDOWN redo 0/AB10260; ...
^
^
In the output above, the LSN 0/AB10260 and 0/0AB10260 refer to the same logical
LSN, but are presented with a different number of leading zeros in the lower
32-bit part.
Upon further investigation, I grepped the source code for the format specifier
used:
$ grep '%X\/%08X' -rn src/
src/bin/pg_waldump/pg_waldump.c:558: printf("rmgr: %-11s len (rec/tot):
%6u/%6u, tx: %10u, lsn: %X/%08X, prev %X/%08X, ",
This inconsistency, while minor, could be confusing when cross-referencing
LSNs within pg_waldump's own output or when parsing it programmatically.
--
Regards,
Japin Li
>From b38d020375481ae54aaf745bee58b7c1a074274b Mon Sep 17 00:00:00 2001
From: Li Jianping <[email protected]>
Date: Tue, 1 Jul 2025 17:42:48 +0800
Subject: [PATCH v1] Fix inconsistent LSN format in pg_waldump
---
src/bin/pg_waldump/pg_waldump.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/bin/pg_waldump/pg_waldump.c b/src/bin/pg_waldump/pg_waldump.c
index 51fb76efc48..5cf55be896d 100644
--- a/src/bin/pg_waldump/pg_waldump.c
+++ b/src/bin/pg_waldump/pg_waldump.c
@@ -555,7 +555,7 @@ XLogDumpDisplayRecord(XLogDumpConfig *config, XLogReaderState *record)
XLogRecGetLen(record, &rec_len, &fpi_len);
- printf("rmgr: %-11s len (rec/tot): %6u/%6u, tx: %10u, lsn: %X/%08X, prev %X/%08X, ",
+ printf("rmgr: %-11s len (rec/tot): %6u/%6u, tx: %10u, lsn: %X/%X, prev %X/%X, ",
desc->rm_name,
rec_len, XLogRecGetTotalLen(record),
XLogRecGetXid(record),
--
2.43.0
