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Commitb6c4b58

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Fix a couple of bugs with wal_log_hints.
1. Replay of the WAL record for setting a bit in the visibility mapcontained an assertion that a full-page image of that record type can onlyoccur with checksums enabled. But it can also happen with wal_log_hints, soremove the assertion. Unlike checksums, wal_log_hints can be changed on thefly, so it would be complicated to figure out if it was enabled at the timethat the WAL record was generated.2. wal_log_hints has the same effect on the locking needed to read the LSNof a page as data checksums. BufferGetLSNAtomic() didn't get the memo.Backpatch to 9.4, where wal_log_hints was added.
1 parent8364510 commitb6c4b58

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2 files changed

+8
-9
lines changed

2 files changed

+8
-9
lines changed

‎src/backend/access/heap/heapam.c

Lines changed: 7 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -7413,12 +7413,11 @@ heap_xlog_visible(XLogRecPtr lsn, XLogRecord *record)
74137413
ResolveRecoveryConflictWithSnapshot(xlrec->cutoff_xid,xlrec->node);
74147414

74157415
/*
7416-
* If heap block was backed up, restore it. This can only happen with
7417-
* checksums enabled.
7416+
* If heap block was backed up, restore it.(This can only happen with
7417+
* checksumsor wal_log_hintsenabled).
74187418
*/
74197419
if (record->xl_info&XLR_BKP_BLOCK(1))
74207420
{
7421-
Assert(DataChecksumsEnabled());
74227421
(void)RestoreBackupBlock(lsn,record,1, false, false);
74237422
}
74247423
else
@@ -7441,11 +7440,11 @@ heap_xlog_visible(XLogRecPtr lsn, XLogRecord *record)
74417440

74427441
/*
74437442
* We don't bump the LSN of the heap page when setting the
7444-
* visibility map bit (unless checksumsare enabled, in which case
7445-
* we must), because that would generate an unworkable volume of
7446-
* full-page writes. This exposes us to torn page hazards, but
7447-
* since we're not inspecting the existing page contents in any
7448-
* way, we don't care.
7443+
* visibility map bit (unless checksumsor wal_log_hints is
7444+
*enabled, in which casewe must), because that would generate an
7445+
*unworkable volume offull-page writes. This exposes us to torn
7446+
*page hazards, butsince we're not inspecting the existing page
7447+
*contents in anyway, we don't care.
74497448
*
74507449
* However, all operations that clear the visibility map bit *do*
74517450
* bump the LSN, and those operations will only be replayed if the

‎src/backend/storage/buffer/bufmgr.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2125,7 +2125,7 @@ BufferGetLSNAtomic(Buffer buffer)
21252125
/*
21262126
* If we don't need locking for correctness, fastpath out.
21272127
*/
2128-
if (!DataChecksumsEnabled()||BufferIsLocal(buffer))
2128+
if (!XLogHintBitIsNeeded()||BufferIsLocal(buffer))
21292129
returnPageGetLSN(page);
21302130

21312131
/* Make sure we've got a real buffer, and that we hold a pin on it. */

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