- Modifies LOCKTAG to include a 'classId'. Relation receive a classId of

RelOid_pg_class, and transaction locks XactLockTableId. RelId is renamed
to objId.

- LockObject() and UnlockObject() functions created, and their use
sprinkled throughout the code to do descent locking for domains and
types. They accept lock modes AccessShare and AccessExclusive, as we
only really need a 'read' and 'write' lock at the moment.  Most locking
cases are held until the end of the transaction.

This fixes the cases Tom mentioned earlier in regards to locking with
Domains.  If the patch is good, I'll work on cleaning up issues with
other database objects that have this problem (most of them).

Rod Taylor

src/include/storage/lock.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: lock.h,v 1.69 2003/02/18 02:13:24 momjian Exp $
+ * $Id: lock.h,v 1.70 2003/02/19 04:02:54 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -100,13 +100,14 @@ typedef struct LOCKMETHODTABLE
  */
 typedef struct LOCKTAG
 {
-	Oid			relId;
+	Oid			objId;
+	Oid			classId;
 	Oid			dbId;
 	union
 	{
 		BlockNumber blkno;
 		TransactionId xid;
-	}			objId;
+	}			objsubId;
 
 	/*
 	 * offnum should be part of objId.tupleId above, but would increase