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Repair problems with VACUUM destroying t_ctid chains too soon, and with
insufficient paranoia in code that follows t_ctid links. (We must do both because even with VACUUM doing it properly, the intermediate state with a dangling t_ctid link is visible concurrently during lazy VACUUM, and could be seen afterwards if either type of VACUUM crashes partway through.) Also try to improve documentation about what's going on. Patch is a bit bulky because passing the XMAX information around required changing the APIs of some low-level heapam.c routines, but it's not conceptually very complicated. Per trouble report from Teodor and subsequent analysis. This needs to be back-patched, but I'll do that after 8.1 beta is out.
1 parent 97bb6e8 commit f57e3f4

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10 files changed

+521
-266
lines changed

10 files changed

+521
-266
lines changed

‎src/backend/access/heap/heapam.c

Lines changed: 189 additions & 93 deletions
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‎src/backend/commands/async.c

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
99
* IDENTIFICATION
10-
* $PostgreSQL: pgsql/src/backend/commands/async.c,v 1.123 2005/06/17 22:32:43 tgl Exp $
10+
* $PostgreSQL: pgsql/src/backend/commands/async.c,v 1.124 2005/08/20 00:39:53 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -550,8 +550,9 @@ AtCommit_Notify(void)
550550
}
551551
else if (listener->notification == 0)
552552
{
553-
ItemPointerData ctid;
554553
HTSU_Result result;
554+
ItemPointerData update_ctid;
555+
TransactionId update_xmax;
555556

556557
rTuple = heap_modifytuple(lTuple, tdesc,
557558
value, nulls, repl);
@@ -573,7 +574,7 @@ AtCommit_Notify(void)
573574
* heap_update calls.
574575
*/
575576
result = heap_update(lRel, &lTuple->t_self, rTuple,
576-
&ctid,
577+
&update_ctid, &update_xmax,
577578
GetCurrentCommandId(), InvalidSnapshot,
578579
false /* no wait for commit */ );
579580
switch (result)
@@ -585,7 +586,6 @@ AtCommit_Notify(void)
585586

586587
case HeapTupleMayBeUpdated:
587588
/* done successfully */
588-
589589
#ifdef NOT_USED /* currently there are no indexes */
590590
CatalogUpdateIndexes(lRel, rTuple);
591591
#endif

‎src/backend/commands/trigger.c

Lines changed: 20 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
99
* IDENTIFICATION
10-
* $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.191 2005/08/12 01:35:57 tgl Exp $
10+
* $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.192 2005/08/20 00:39:54 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -1592,14 +1592,18 @@ GetTupleForTrigger(EState *estate, ResultRelInfo *relinfo,
15921592
if (newSlot != NULL)
15931593
{
15941594
HTSU_Result test;
1595+
ItemPointerData update_ctid;
1596+
TransactionId update_xmax;
1597+
1598+
*newSlot = NULL;
15951599

15961600
/*
15971601
* lock tuple for update
15981602
*/
1599-
*newSlot = NULL;
1600-
tuple.t_self = *tid;
16011603
ltrmark:;
1602-
test = heap_lock_tuple(relation, &tuple, &buffer, cid,
1604+
tuple.t_self = *tid;
1605+
test = heap_lock_tuple(relation, &tuple, &buffer,
1606+
&update_ctid, &update_xmax, cid,
16031607
LockTupleExclusive, false);
16041608
switch (test)
16051609
{
@@ -1617,15 +1621,18 @@ ltrmark:;
16171621
ereport(ERROR,
16181622
(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
16191623
errmsg("could not serialize access due to concurrent update")));
1620-
else if (!(ItemPointerEquals(&(tuple.t_self), tid)))
1624+
else if (!ItemPointerEquals(&update_ctid, &tuple.t_self))
16211625
{
1622-
TupleTableSlot *epqslot = EvalPlanQual(estate,
1623-
relinfo->ri_RangeTableIndex,
1624-
&(tuple.t_self));
1625-
1626-
if (!(TupIsNull(epqslot)))
1626+
/* it was updated, so look at the updated version */
1627+
TupleTableSlot *epqslot;
1628+
1629+
epqslot = EvalPlanQual(estate,
1630+
relinfo->ri_RangeTableIndex,
1631+
&update_ctid,
1632+
update_xmax);
1633+
if (!TupIsNull(epqslot))
16271634
{
1628-
*tid = tuple.t_self;
1635+
*tid = update_ctid;
16291636
*newSlot = epqslot;
16301637
goto ltrmark;
16311638
}
@@ -1639,7 +1646,7 @@ ltrmark:;
16391646

16401647
default:
16411648
ReleaseBuffer(buffer);
1642-
elog(ERROR, "invalid heap_lock_tuple status: %d", test);
1649+
elog(ERROR, "unrecognized heap_lock_tuple status: %u", test);
16431650
return NULL; /* keep compiler quiet */
16441651
}
16451652
}
@@ -1659,6 +1666,7 @@ ltrmark:;
16591666
tuple.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
16601667
tuple.t_len = ItemIdGetLength(lp);
16611668
tuple.t_self = *tid;
1669+
tuple.t_tableOid = RelationGetRelid(relation);
16621670
}
16631671

16641672
result = heap_copytuple(&tuple);

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