From b6c4b58ac52aa9046c45bd8c2c9fc8925087c8d3 Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Fri, 26 Jun 2015 12:38:24 +0300 Subject: [PATCH] Fix a couple of bugs with wal_log_hints. 1. Replay of the WAL record for setting a bit in the visibility map contained an assertion that a full-page image of that record type can only occur with checksums enabled. But it can also happen with wal_log_hints, so remove the assertion. Unlike checksums, wal_log_hints can be changed on the fly, so it would be complicated to figure out if it was enabled at the time that the WAL record was generated. 2. wal_log_hints has the same effect on the locking needed to read the LSN of a page as data checksums. BufferGetLSNAtomic() didn't get the memo. Backpatch to 9.4, where wal_log_hints was added. --- src/backend/access/heap/heapam.c | 15 +++++++-------- src/backend/storage/buffer/bufmgr.c | 2 +- 2 files changed, 8 insertions(+), 9 deletions(-) diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c index 2209db1d96b..2e3b9d2c2b7 100644 --- a/src/backend/access/heap/heapam.c +++ b/src/backend/access/heap/heapam.c @@ -7413,12 +7413,11 @@ heap_xlog_visible(XLogRecPtr lsn, XLogRecord *record) ResolveRecoveryConflictWithSnapshot(xlrec->cutoff_xid, xlrec->node); /* - * If heap block was backed up, restore it. This can only happen with - * checksums enabled. + * If heap block was backed up, restore it. (This can only happen with + * checksums or wal_log_hints enabled). */ if (record->xl_info & XLR_BKP_BLOCK(1)) { - Assert(DataChecksumsEnabled()); (void) RestoreBackupBlock(lsn, record, 1, false, false); } else @@ -7441,11 +7440,11 @@ heap_xlog_visible(XLogRecPtr lsn, XLogRecord *record) /* * We don't bump the LSN of the heap page when setting the - * visibility map bit (unless checksums are enabled, in which case - * we must), because that would generate an unworkable volume of - * full-page writes. This exposes us to torn page hazards, but - * since we're not inspecting the existing page contents in any - * way, we don't care. + * visibility map bit (unless checksums or wal_log_hints is + * enabled, in which case we must), because that would generate an + * unworkable volume of full-page writes. This exposes us to torn + * page hazards, but since we're not inspecting the existing page + * contents in any way, we don't care. * * However, all operations that clear the visibility map bit *do* * bump the LSN, and those operations will only be replayed if the diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c index 19ec7eb231e..18013d59ebf 100644 --- a/src/backend/storage/buffer/bufmgr.c +++ b/src/backend/storage/buffer/bufmgr.c @@ -2125,7 +2125,7 @@ BufferGetLSNAtomic(Buffer buffer) /* * If we don't need locking for correctness, fastpath out. */ - if (!DataChecksumsEnabled() || BufferIsLocal(buffer)) + if (!XLogHintBitIsNeeded() || BufferIsLocal(buffer)) return PageGetLSN(page); /* Make sure we've got a real buffer, and that we hold a pin on it. */ -- 2.39.5