From 547a8aaa7d4fffd686c75b1e00b1c11c0980aabc Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Mon, 16 Feb 2026 17:16:59 +0200 Subject: [PATCH] Don't reset 'latest_page_number' when replaying multixid truncation 'latest_page_number' is set to the correct value, according to nextOffset, early at system startup. Contrary to the comment, it hence should be set up correctly by the time we get to WAL replay. This fixes a failure to replay WAL generated on older minor versions, before commit 789d65364c (18.2, 17.8, 16.12, 15.16, 14.21). The failure occurs after a truncation record has been replayed and looks like this: FATAL: could not access status of transaction 858112 DETAIL: Could not read from file "pg_multixact/offsets/000D" at offset 24576: read too few bytes. CONTEXT: WAL redo at 3/2A3AB408 for MultiXact/CREATE_ID: 858111 offset 6695072 nmembers 5: 1048228 (sh) 1048271 (keysh) 1048316 (sh) 1048344 (keysh) 1048370 (sh) Reported-by: Sebastian Webber Reviewed-by: Andrey Borodin Reviewed-by: Kirill Reshke Discussion: https://www.postgresql.org/message-id/20260214090150.GC2297@p46.dedyn.io;lightning.p46.dedyn.io Backpatch-through: 14-18 --- src/backend/access/transam/multixact.c | 9 --------- src/include/access/slru.h | 4 +++- 2 files changed, 3 insertions(+), 10 deletions(-) diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c index e5f5d098668..cd8eb1898af 100644 --- a/src/backend/access/transam/multixact.c +++ b/src/backend/access/transam/multixact.c @@ -3438,7 +3438,6 @@ multixact_redo(XLogReaderState *record) else if (info == XLOG_MULTIXACT_TRUNCATE_ID) { xl_multixact_truncate xlrec; - int pageno; memcpy(&xlrec, XLogRecGetData(record), SizeOfMultiXactTruncate); @@ -3463,14 +3462,6 @@ multixact_redo(XLogReaderState *record) SetMultiXactIdLimit(xlrec.endTruncOff, xlrec.oldestMultiDB, false); PerformMembersTruncation(xlrec.startTruncMemb, xlrec.endTruncMemb); - - /* - * During XLOG replay, latest_page_number isn't necessarily set up - * yet; insert a suitable value to bypass the sanity test in - * SimpleLruTruncate. - */ - pageno = MultiXactIdToOffsetPage(xlrec.endTruncOff); - MultiXactOffsetCtl->shared->latest_page_number = pageno; PerformOffsetsTruncation(xlrec.startTruncOff, xlrec.endTruncOff); LWLockRelease(MultiXactTruncationLock); diff --git a/src/include/access/slru.h b/src/include/access/slru.h index dd52e8cec7e..558f7d9abb2 100644 --- a/src/include/access/slru.h +++ b/src/include/access/slru.h @@ -93,7 +93,9 @@ typedef struct SlruSharedData /* * latest_page_number is the page number of the current end of the log; * this is not critical data, since we use it only to avoid swapping out - * the latest page. + * the latest page. (An exception: an accurate latest_page_number is + * needed on pg_multixact/offsets to replay WAL generated with older minor + * versions correctly. See RecordNewMultiXact().) */ int latest_page_number;