diff options
Diffstat (limited to 'src/backend/access/index/indexam.c')
| -rw-r--r-- | src/backend/access/index/indexam.c | 29 |
1 files changed, 23 insertions, 6 deletions
diff --git a/src/backend/access/index/indexam.c b/src/backend/access/index/indexam.c index bd2e3bdd06e..c1e61ff2bda 100644 --- a/src/backend/access/index/indexam.c +++ b/src/backend/access/index/indexam.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/access/index/indexam.c,v 1.86 2005/10/15 02:49:09 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/access/index/indexam.c,v 1.87 2005/12/03 05:51:00 tgl Exp $ * * INTERFACE ROUTINES * index_open - open an index relation by relation OID @@ -111,6 +111,7 @@ do { \ } while(0) static IndexScanDesc index_beginscan_internal(Relation indexRelation, + bool need_index_lock, int nkeys, ScanKey key); @@ -229,16 +230,23 @@ index_insert(Relation indexRelation, * heapRelation link (nor the snapshot). However, the caller had better * be holding some kind of lock on the heap relation in any case, to ensure * no one deletes it (or the index) out from under us. + * + * Most callers should pass need_index_lock = true to cause the index code + * to take AccessShareLock on the index for the duration of the scan. But + * if it is known that a lock is already held on the index, pass false to + * skip taking an unnecessary lock. */ IndexScanDesc index_beginscan(Relation heapRelation, Relation indexRelation, + bool need_index_lock, Snapshot snapshot, int nkeys, ScanKey key) { IndexScanDesc scan; - scan = index_beginscan_internal(indexRelation, nkeys, key); + scan = index_beginscan_internal(indexRelation, need_index_lock, + nkeys, key); /* * Save additional parameters into the scandesc. Everything else was set @@ -259,12 +267,14 @@ index_beginscan(Relation heapRelation, */ IndexScanDesc index_beginscan_multi(Relation indexRelation, + bool need_index_lock, Snapshot snapshot, int nkeys, ScanKey key) { IndexScanDesc scan; - scan = index_beginscan_internal(indexRelation, nkeys, key); + scan = index_beginscan_internal(indexRelation, need_index_lock, + nkeys, key); /* * Save additional parameters into the scandesc. Everything else was set @@ -281,6 +291,7 @@ index_beginscan_multi(Relation indexRelation, */ static IndexScanDesc index_beginscan_internal(Relation indexRelation, + bool need_index_lock, int nkeys, ScanKey key) { IndexScanDesc scan; @@ -291,13 +302,15 @@ index_beginscan_internal(Relation indexRelation, RelationIncrementReferenceCount(indexRelation); /* - * Acquire AccessShareLock for the duration of the scan + * Acquire AccessShareLock for the duration of the scan, unless caller + * says it already has lock on the index. * * Note: we could get an SI inval message here and consequently have to * rebuild the relcache entry. The refcount increment above ensures that * we will rebuild it and not just flush it... */ - LockRelation(indexRelation, AccessShareLock); + if (need_index_lock) + LockRelation(indexRelation, AccessShareLock); /* * LockRelation can clean rd_aminfo structure, so fill procedure after @@ -315,6 +328,9 @@ index_beginscan_internal(Relation indexRelation, Int32GetDatum(nkeys), PointerGetDatum(key))); + /* Save flag to tell index_endscan whether to release lock */ + scan->have_lock = need_index_lock; + return scan; } @@ -380,7 +396,8 @@ index_endscan(IndexScanDesc scan) /* Release index lock and refcount acquired by index_beginscan */ - UnlockRelation(scan->indexRelation, AccessShareLock); + if (scan->have_lock) + UnlockRelation(scan->indexRelation, AccessShareLock); RelationDecrementReferenceCount(scan->indexRelation); |