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Fix WAL replay of locking an updated tuple 

We were resetting the tuple's HEAP_HOT_UPDATED flag as well as t_ctid on
WAL replay of a tuple-lock operation, which is incorrect when the tuple
is already updated.

Back-patch to 9.3.  The clearing of both header elements was there
previously, but since no update could be present on a tuple that was
being locked, it was harmless.

Bug reported by Peter Geoghegan and Greg Stark in
CAM3SWZTMQiCi5PV5OWHb+bYkUcnCk=O67w0cSswPvV7XfUcU5g@mail.gmail.com and
CAM-w4HPTOeMT4KP0OJK+mGgzgcTOtLRTvFZyvD0O4aH-7dxo3Q@mail.gmail.com
respectively; diagnosis by Andres Freund.
This commit is contained in:
Alvaro Herrera 2014-02-27 11:13:39 -03:00
parent 00976f202c
commit 6bfa88acd3
1 changed files with 11 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
src/backend/access/heap/heapam.c
View File

@ -8016,11 +8016,19 @@ heap_xlog_lock(XLogRecPtr lsn, XLogRecord *record)
fix_infomask_from_infobits(xlrec->infobits_set, &htup->t_infomask,
&htup->t_infomask2);
HeapTupleHeaderClearHotUpdated(htup);
/*
* Clear relevant update flags, but only if the modified infomask says
* there's no update.
*/
if (HEAP_XMAX_IS_LOCKED_ONLY(htup->t_infomask))
{
HeapTupleHeaderClearHotUpdated(htup);
/* Make sure there is no forward chain link in t_ctid */
htup->t_ctid = xlrec->target.tid;
}
HeapTupleHeaderSetXmax(htup, xlrec->locking_xid);
HeapTupleHeaderSetCmax(htup, FirstCommandId, false);
/* Make sure there is no forward chain link in t_ctid */
htup->t_ctid = xlrec->target.tid;
PageSetLSN(page, lsn);
MarkBufferDirty(buffer);
UnlockReleaseBuffer(buffer);