From 75d091a0d70e0fce075ed284bd4ed741ca84a0f9 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 25 Aug 2007 19:08:19 +0000 Subject: [PATCH] Fix brain fade in DefineIndex(): it was continuing to access the table's relcache entry after having heap_close'd it. This could lead to misbehavior if a relcache flush wiped out the cache entry meanwhile. In 8.2 there is a very real risk of CREATE INDEX CONCURRENTLY using the wrong relid for locking and waiting purposes. I think the bug is only cosmetic in 8.0 and 8.1, because their transgression is limited to using RelationGetRelationName(rel) in an ereport message immediately after heap_close, and there's no way (except with special debugging options) for a cache flush to occur in that interval. Not quite sure that it's cosmetic in 7.4, but seems best to patch anyway. Found by trying to run the regression tests with CLOBBER_CACHE_ALWAYS enabled. Maybe we should try to do that on a regular basis --- it's awfully slow, but perhaps some fast buildfarm machine could do it once in awhile. --- src/backend/commands/indexcmds.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c index 943662f8f8..d79e73f59d 100644 --- a/src/backend/commands/indexcmds.c +++ b/src/backend/commands/indexcmds.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/commands/indexcmds.c,v 1.161 2007/07/17 05:02:00 neilc Exp $ + * $PostgreSQL: pgsql/src/backend/commands/indexcmds.c,v 1.162 2007/08/25 19:08:19 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -428,8 +428,6 @@ DefineIndex(RangeVar *heapRelation, relationId, accessMethodName, accessMethodId, amcanorder, isconstraint); - heap_close(rel, NoLock); - /* * Report index creation if appropriate (delay this till after most of the * error checks) @@ -441,6 +439,10 @@ DefineIndex(RangeVar *heapRelation, primary ? "PRIMARY KEY" : "UNIQUE", indexRelationName, RelationGetRelationName(rel)))); + /* save lockrelid for below, then close rel */ + heaprelid = rel->rd_lockInfo.lockRelId; + heap_close(rel, NoLock); + indexRelationId = index_create(relationId, indexRelationName, indexRelationId, indexInfo, accessMethodId, tablespaceId, classObjectId, @@ -468,7 +470,6 @@ DefineIndex(RangeVar *heapRelation, * because there are no operations that could change its state while we * hold lock on the parent table. This might need to change later. */ - heaprelid = rel->rd_lockInfo.lockRelId; LockRelationIdForSession(&heaprelid, ShareUpdateExclusiveLock); CommitTransactionCommand(); -- 2.40.0