From e5b86c93b66b5caeb25a65bae26b04fc7a068957 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Fri, 16 Sep 2011 14:47:27 -0400 Subject: Avoid unnecessary page-level SSI lock check in heap_insert(). As observed by Heikki, we need not conflict on heap page locks during an insert; heap page locks are only aggregated tuple locks, they don't imply locking "gaps" as index page locks do. So we can avoid some unnecessary conflicts, and also do the SSI check while not holding exclusive lock on the target buffer. Kevin Grittner, reviewed by Jeff Davis. Back-patch to 9.1. --- src/backend/access/heap/heapam.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) (limited to 'src') diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c index 450bb15ff8d..cc8b45fd489 100644 --- a/src/backend/access/heap/heapam.c +++ b/src/backend/access/heap/heapam.c @@ -1921,17 +1921,22 @@ heap_insert(Relation relation, HeapTuple tup, CommandId cid, else heaptup = tup; + /* + * We're about to do the actual insert -- but check for conflict first, + * to avoid possibly having to roll back work we've just done. + * + * For a heap insert, we only need to check for table-level SSI locks. + * Our new tuple can't possibly conflict with existing tuple locks, and + * heap page locks are only consolidated versions of tuple locks; they do + * not lock "gaps" as index page locks do. So we don't need to identify + * a buffer before making the call. + */ + CheckForSerializableConflictIn(relation, NULL, InvalidBuffer); + /* Find buffer to insert this tuple into */ buffer = RelationGetBufferForTuple(relation, heaptup->t_len, InvalidBuffer, options, bistate); - /* - * We're about to do the actual insert -- check for conflict at the - * relation or buffer level first, to avoid possibly having to roll back - * work we've just done. - */ - CheckForSerializableConflictIn(relation, NULL, buffer); - /* NO EREPORT(ERROR) from here till changes are logged */ START_CRIT_SECTION(); -- cgit v1.2.3