diff options
Diffstat (limited to 'src/backend/executor/execUtils.c')
| -rw-r--r-- | src/backend/executor/execUtils.c | 39 |
1 files changed, 21 insertions, 18 deletions
diff --git a/src/backend/executor/execUtils.c b/src/backend/executor/execUtils.c index a1736766b26..638a4f73dfc 100644 --- a/src/backend/executor/execUtils.c +++ b/src/backend/executor/execUtils.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/executor/execUtils.c,v 1.115 2004/09/11 18:28:34 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/executor/execUtils.c,v 1.116 2004/09/30 23:21:23 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -682,28 +682,29 @@ ExecOpenIndices(ResultRelInfo *resultRelInfo) IndexInfo *ii; /* - * Open (and lock, if necessary) the index relation + * Open and lock the index relation + * + * If the index AM supports concurrent updates, obtain RowExclusiveLock + * to signify that we are updating the index. This locks out only + * operations that need exclusive access, such as relocating the index + * to a new tablespace. * * If the index AM is not safe for concurrent updates, obtain an * exclusive lock on the index to lock out other updaters as well - * as readers (index_beginscan places AccessShareLock). We will - * release this lock in ExecCloseIndices. - * - * If the index AM supports concurrent updates, we obtain no lock - * here at all, which is a tad weird, but safe since any critical - * operation on the index (like deleting it) will acquire - * exclusive lock on the parent table. Perhaps someday we should - * acquire RowExclusiveLock on the index here? + * as readers (index_beginscan places AccessShareLock). * * If there are multiple not-concurrent-safe indexes, all backends - * must lock the indexes in the same order or we will get - * deadlocks here during concurrent updates. This is guaranteed - * by RelationGetIndexList(), which promises to return the index - * list in OID order. + * must lock the indexes in the same order or we will get deadlocks + * here. This is guaranteed by RelationGetIndexList(), which promises + * to return the index list in OID order. + * + * The locks will be released in ExecCloseIndices. */ indexDesc = index_open(indexOid); - if (!indexDesc->rd_am->amconcurrent) + if (indexDesc->rd_am->amconcurrent) + LockRelation(indexDesc, RowExclusiveLock); + else LockRelation(indexDesc, AccessExclusiveLock); /* extract index key information from the index's pg_index info */ @@ -736,10 +737,12 @@ ExecCloseIndices(ResultRelInfo *resultRelInfo) for (i = 0; i < numIndices; i++) { if (indexDescs[i] == NULL) - continue; + continue; /* shouldn't happen? */ - /* Drop lock, if one was acquired by ExecOpenIndices */ - if (!indexDescs[i]->rd_am->amconcurrent) + /* Drop lock acquired by ExecOpenIndices */ + if (indexDescs[i]->rd_am->amconcurrent) + UnlockRelation(indexDescs[i], RowExclusiveLock); + else UnlockRelation(indexDescs[i], AccessExclusiveLock); index_close(indexDescs[i]); |