From 817f74600d0d015309596762c9e4a07e0ac8fdbf 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 | 10 ---------- src/include/access/slru.h | 4 +++- 2 files changed, 3 insertions(+), 11 deletions(-) diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c index d5ac2d87380..08a1d08b547 100644 --- a/src/backend/access/transam/multixact.c +++ b/src/backend/access/transam/multixact.c @@ -3577,7 +3577,6 @@ multixact_redo(XLogReaderState *record) else if (info == XLOG_MULTIXACT_TRUNCATE_ID) { xl_multixact_truncate xlrec; - int64 pageno; memcpy(&xlrec, XLogRecGetData(record), SizeOfMultiXactTruncate); @@ -3602,15 +3601,6 @@ 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); - pg_atomic_write_u64(&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 d5ca3447208..f8bf1f1430f 100644 --- a/src/include/access/slru.h +++ b/src/include/access/slru.h @@ -110,7 +110,9 @@ 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().) */ pg_atomic_uint64 latest_page_number;