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VACUUM must make sure that a HEAP_MARKED_FOR_UPDATE tuple gets marked

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as either HEAP_XMAX_COMMITTED or HEAP_XMAX_INVALID once the updating
transaction is gone.  Otherwise some other transaction may come along
and try to test the commit status of t_xmax later --- which could be
after VACUUM has recycled the CLOG status for that xact.  Bug introduced
in post-beta4 bug fix.
This commit is contained in:
Tom Lane 2002-01-11 20:07:03 +00:00
parent eb5e8bae26
commit 5ab0ad5c7e
1 changed files with 16 additions and 2 deletions
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18
src/backend/utils/time/tqual.c
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@ -8,7 +8,7 @@
* *
* *
* IDENTIFICATION * IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.45 2001/12/19 17:18:39 tgl Exp $ * $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.46 2002/01/11 20:07:03 tgl Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -742,7 +742,21 @@ HeapTupleSatisfiesVacuum(HeapTupleHeader tuple, TransactionId OldestXmin)
if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE) if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
{ {
/* "deleting" xact really only marked it for update */ /*
* "Deleting" xact really only marked it for update, so the tuple
* is live in any case. However, we must make sure that either
* XMAX_COMMITTED or XMAX_INVALID gets set once the xact is gone;
* otherwise it is unsafe to recycle CLOG status after vacuuming.
*/
if (!(tuple->t_infomask & HEAP_XMAX_COMMITTED))
{
if (TransactionIdIsInProgress(tuple->t_xmax))
return HEAPTUPLE_LIVE;
if (TransactionIdDidCommit(tuple->t_xmax))
tuple->t_infomask |= HEAP_XMAX_COMMITTED;
else /* it's either aborted or crashed */
tuple->t_infomask |= HEAP_XMAX_INVALID;
}
return HEAPTUPLE_LIVE; return HEAPTUPLE_LIVE;
} }