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Commit04103e0

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Modify uses of RelationFlushRelation and RelationCacheInvalidate so that
we *always* rebuild, rather than deleting, an invalidated relcache entrythat has positive refcount. Otherwise an SI cache overrun leads todangling Relation pointers all over the place!
1 parent98c6e81 commit04103e0

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2 files changed

+27
-9
lines changed

2 files changed

+27
-9
lines changed

‎src/backend/utils/cache/inval.c

Lines changed: 5 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/utils/cache/inval.c,v 1.32 2000/01/26 05:57:17 momjian Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/utils/cache/inval.c,v 1.33 2000/01/29 19:51:59 tgl Exp $
1212
*
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* Note - this code is real crufty...
1414
*
@@ -548,15 +548,16 @@ CacheIdInvalidate(Index cacheId,
548548
/* --------------------------------
549549
*ResetSystemCaches
550550
*
551-
*this blows away all tuples in the system catalog caches and
552-
*all the cached relation descriptors (and closes the files too).
551+
*This blows away all tuples in the system catalog caches and
552+
*all the cached relation descriptors (and closes their files too).
553+
*Relation descriptors that have positive refcounts are then rebuilt.
553554
* --------------------------------
554555
*/
555556
staticvoid
556557
ResetSystemCaches()
557558
{
558559
ResetSystemCache();
559-
RelationCacheInvalidate(false);
560+
RelationCacheInvalidate(true);
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}
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562563
/* --------------------------------

‎src/backend/utils/cache/relcache.c

Lines changed: 22 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
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*
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* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/utils/cache/relcache.c,v 1.87 2000/01/26 05:57:17 momjian Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/utils/cache/relcache.c,v 1.88 2000/01/29 19:51:59 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -1406,14 +1406,26 @@ RelationIdInvalidateRelationCacheByRelationId(Oid relationId)
14061406
*/
14071407
if (PointerIsValid(relation)&& !relation->rd_myxactonly)
14081408
{
1409-
1409+
#if1
1410+
/*
1411+
* Seems safest just to NEVER flush rels with positive refcounts.
1412+
* I think the code only had that proviso as a rather lame method of
1413+
* cleaning up unused relcache entries that had dangling refcounts
1414+
* (following elog(ERROR) with an open rel). Now we rely on
1415+
* RelationCacheAbort to clean up dangling refcounts, so there's no
1416+
* good reason to ever risk flushing a rel with positive refcount.
1417+
* IMHO anyway --- tgl 1/29/00.
1418+
*/
1419+
RelationFlushRelation(&relation, true);
1420+
#else
14101421
/*
14111422
* The boolean onlyFlushReferenceCountZero in RelationFlushReln()
14121423
* should be set to true when we are incrementing the command
14131424
* counter and to false when we are starting a new xaction. This
14141425
* can be determined by checking the current xaction status.
14151426
*/
14161427
RelationFlushRelation(&relation,CurrentXactInProgress());
1428+
#endif
14171429
}
14181430
}
14191431

@@ -1436,7 +1448,7 @@ RelationFlushIndexes(Relation *r,
14361448
if (relation->rd_rel->relkind==RELKIND_INDEX&&/* XXX style */
14371449
(!OidIsValid(accessMethodId)||
14381450
relation->rd_rel->relam==accessMethodId))
1439-
RelationFlushRelation(&relation,false);
1451+
RelationFlushRelation(&relation,true);
14401452
}
14411453

14421454
#endif
@@ -1469,9 +1481,14 @@ RelationIdInvalidateRelationCacheByAccessMethodId(Oid accessMethodId)
14691481
* Will blow away either all the cached relation descriptors or
14701482
* those that have a zero reference count.
14711483
*
1484+
* CAUTION: this is only called with onlyFlushReferenceCountZero=true
1485+
* at present, so that relation descriptors with positive refcounts
1486+
* are rebuilt rather than clobbered. It would only be safe to use a
1487+
* "false" parameter in a totally idle backend with no open relations.
1488+
*
14721489
* This is currently used only to recover from SI message buffer overflow,
1473-
* soonlyFlushReferenceCountZero is always false. We do not blow away
1474-
*transaction-local relations, since they cannot betargets of SI updates.
1490+
* sowe do not blow away transaction-local relations; they cannot be
1491+
* targets of SI updates.
14751492
*/
14761493
void
14771494
RelationCacheInvalidate(boolonlyFlushReferenceCountZero)

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