Fix relation-to-view conversion so that it doesn't try to convert a plain

relation to a view when you create an ON INSERT/UPDATE/DELETE rule ...

diff --git a/src/backend/rewrite/rewriteDefine.c b/src/backend/rewrite/rewriteDefine.c
index 8444bd9138423c985097d50837ba4087c393507a..da0d84ad9d5eda303e18bfe91e94b8973afb0d49 100644 (file)
--- a/src/backend/rewrite/rewriteDefine.c
+++ b/src/backend/rewrite/rewriteDefine.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteDefine.c,v 1.51 2000/09/12 04:49:09 momjian Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteDefine.c,v 1.52 2000/09/12 20:38:09 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -200,40 +200,16 @@ DefineQueryRewrite(RuleStmt *stmt)
        foreach(l, action)
        {
                query = (Query *) lfirst(l);
-               if (query->resultRelation == 1)
+               if (query->resultRelation == PRS2_OLD_VARNO)
                {
                        elog(ERROR, "rule actions on OLD currently not supported"
                                 "\n\tuse views or triggers instead");
                }
-               if (query->resultRelation == 2)
+               if (query->resultRelation == PRS2_NEW_VARNO)
                {
                        elog(ERROR, "rule actions on NEW currently not supported"
                                 "\n\tuse triggers instead");
                }
-
-               if (event_relation->rd_rel->relkind != RELKIND_VIEW)
-               {
-                       HeapScanDesc  scanDesc;
-                       HeapTuple         tuple;
-                       /*
-                        * A relation is about to become a view.
-                        * check that the relation is empty because
-                        * the storage for the relation is going to
-                        * be deleted.
-                        */
-
-                       scanDesc = heap_beginscan(event_relation, 0, SnapshotNow, 0, NULL);
-                       tuple = heap_getnext(scanDesc, 0);
-                       if (HeapTupleIsValid(tuple))
-                               elog(ERROR, "relation %s is not empty. Cannot convert to view", event_obj->relname);
-
-                       /* don't need heap_freetuple because we never got a valid tuple */
-                       heap_endscan(scanDesc);
-
-
-                       RelisBecomingView = true;
-               }
-
        }
 
        /*
@@ -333,7 +309,6 @@ DefineQueryRewrite(RuleStmt *stmt)
                /*
                 * ... and finally the rule must be named _RETviewname.
                 */
-
                expected_name = MakeRetrieveViewRuleName(event_obj->relname);
                if (strcmp(expected_name, stmt->rulename) != 0)
                {
@@ -341,6 +316,29 @@ DefineQueryRewrite(RuleStmt *stmt)
                                 event_obj->relname, expected_name);
                }
                pfree(expected_name);
+
+               /*
+                * Are we converting a relation to a view?
+                *
+                * If so, check that the relation is empty because the storage
+                * for the relation is going to be deleted.
+                */
+               if (event_relation->rd_rel->relkind != RELKIND_VIEW)
+               {
+                       HeapScanDesc  scanDesc;
+                       HeapTuple         tuple;
+
+                       scanDesc = heap_beginscan(event_relation, 0, SnapshotNow, 0, NULL);
+                       tuple = heap_getnext(scanDesc, 0);
+                       if (HeapTupleIsValid(tuple))
+                               elog(ERROR, "Relation \"%s\" is not empty. Cannot convert it to view",
+                                        event_obj->relname);
+
+                       /* don't need heap_freetuple because we never got a valid tuple */
+                       heap_endscan(scanDesc);
+
+                       RelisBecomingView = true;
+               }
        }
 
        /*
@@ -363,7 +361,7 @@ DefineQueryRewrite(RuleStmt *stmt)
                                 is_instead, event_attype);
 
        /* discard rule if it's null action and not INSTEAD; it's a no-op */
-       if (action != NULL || is_instead)
+       if (action != NIL || is_instead)
        {
                Relation        relationRelation;
                HeapTuple       tuple;
@@ -382,8 +380,8 @@ DefineQueryRewrite(RuleStmt *stmt)
 
                /*
                 * Set pg_class 'relhasrules' field TRUE for event relation.
-                * Also modify the 'relkind' field to show that the relation is
-                * now a view.
+                * If appropriate, also modify the 'relkind' field to show that
+                * the relation is now a view.
                 *
                 * Important side effect: an SI notice is broadcast to force all
                 * backends (including me!) to update relcache entries with the new
@@ -398,8 +396,8 @@ DefineQueryRewrite(RuleStmt *stmt)
                 */
                relationRelation = heap_openr(RelationRelationName, RowExclusiveLock);
                tuple = SearchSysCacheTupleCopy(RELOID,
-                                                                       ObjectIdGetDatum(ev_relid),
-                                                                       0, 0, 0);
+                                                                               ObjectIdGetDatum(ev_relid),
+                                                                               0, 0, 0);
                Assert(HeapTupleIsValid(tuple));
 
                /* Do the update */
@@ -420,12 +418,12 @@ DefineQueryRewrite(RuleStmt *stmt)
 
        /*
         * IF the relation is becoming a view, delete the storage
-        * files associated with it.
+        * files associated with it.  NB: we had better have AccessExclusiveLock
+        * to do this ...
         */
        if (RelisBecomingView)
                smgrunlink(DEFAULT_SMGR, event_relation);
 
-
        /* Close rel, but keep lock till commit... */
        heap_close(event_relation, NoLock);
 }