Fallout from changing index locking rules: we can reduce the strength

of locking used by REINDEX.  REINDEX needs only ShareLock on the parent
table, same as CREATE INDEX, plus an exclusive lock on the specific index
being processed.

1 files changed, 9 insertions, 2 deletions

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index ba58251919b..ed76fe8fb8c 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/plancat.c,v 1.96 2004/08/29 05:06:44 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/plancat.c,v 1.97 2004/10/01 17:11:50 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -90,7 +90,14 @@ get_relation_info(Oid relationObjectId, RelOptInfo *rel)
 			int			i;
 			int16		amorderstrategy;
 
-			/* Extract info from the relation descriptor for the index */
+			/*
+			 * Extract info from the relation descriptor for the index.
+			 *
+			 * Note that we take no lock on the index; we assume our lock on
+			 * the parent table will protect the index's schema information.
+			 * When and if the executor actually uses the index, it will take
+			 * a lock as needed to protect the access to the index contents.
+			 */
 			indexRelation = index_open(indexoid);
 			index = indexRelation->rd_index;