diff options
Diffstat (limited to 'src/backend/access/index/indexam.c')
| -rw-r--r-- | src/backend/access/index/indexam.c | 49 |
1 files changed, 43 insertions, 6 deletions
diff --git a/src/backend/access/index/indexam.c b/src/backend/access/index/indexam.c index 869e5e1e690..6ad242c0c39 100644 --- a/src/backend/access/index/indexam.c +++ b/src/backend/access/index/indexam.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/access/index/indexam.c,v 1.35 1999/07/16 04:58:28 momjian Exp $ + * $Header: /cvsroot/pgsql/src/backend/access/index/indexam.c,v 1.36 1999/09/18 19:06:04 tgl Exp $ * * INTERFACE ROUTINES * index_open - open an index relation by relationId @@ -129,26 +129,49 @@ * index_open - open an index relation by relationId * * presently the relcache routines do all the work we need - * to open/close index relations. + * to open/close index relations. However, callers of index_open + * expect it to succeed, so we need to check for a failure return. + * + * Note: we acquire no lock on the index. An AccessShareLock is + * acquired by index_beginscan (and released by index_endscan). * ---------------- */ Relation index_open(Oid relationId) { - return RelationIdGetRelation(relationId); + Relation r; + + r = RelationIdGetRelation(relationId); + + if (! RelationIsValid(r)) + elog(ERROR, "Index %u does not exist", relationId); + + if (r->rd_rel->relkind != RELKIND_INDEX) + elog(ERROR, "%s is not an index relation", r->rd_rel->relname.data); + + return r; } /* ---------------- * index_openr - open a index relation by name * - * presently the relcache routines do all the work we need - * to open/close index relations. + * As above, but lookup by name instead of OID. * ---------------- */ Relation index_openr(char *relationName) { - return RelationNameGetRelation(relationName); + Relation r; + + r = RelationNameGetRelation(relationName); + + if (! RelationIsValid(r)) + elog(ERROR, "Index '%s' does not exist", relationName); + + if (r->rd_rel->relkind != RELKIND_INDEX) + elog(ERROR, "%s is not an index relation", r->rd_rel->relname.data); + + return r; } /* ---------------- @@ -223,6 +246,16 @@ index_beginscan(Relation relation, RELATION_CHECKS; GET_REL_PROCEDURE(beginscan, ambeginscan); + RelationIncrementReferenceCount(relation); + + /* ---------------- + * Acquire AccessShareLock for the duration of the scan + * + * 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(relation, AccessShareLock); scandesc = (IndexScanDesc) @@ -260,7 +293,11 @@ index_endscan(IndexScanDesc scan) fmgr(procedure, scan); + /* Release lock and refcount acquired by index_beginscan */ + UnlockRelation(scan->relation, AccessShareLock); + + RelationDecrementReferenceCount(scan->relation); } /* ---------------- |