Fix the plan-invalidation mechanism to treat regclass constants that refer to

a relation as a reason to invalidate a plan when the relation changes.  This
handles scenarios such as dropping/recreating a sequence that is referenced by
nextval('seq') in a cached plan.  Rather than teach plancache.c all about
digging through plan trees to find regclass Consts, we charge the planner's
setrefs.c with making a list of the relation OIDs on which each plan depends.
That way the list can be built cheaply during a plan tree traversal that has
to happen anyway.  Per bug #3662 and subsequent discussion.

src/backend/nodes/copyfuncs.c

@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.382 2007/09/03 18:46:30 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.383 2007/10/11 18:05:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -83,6 +83,7 @@ _copyPlannedStmt(PlannedStmt *from)
 	COPY_BITMAPSET_FIELD(rewindPlanIDs);
 	COPY_NODE_FIELD(returningLists);
 	COPY_NODE_FIELD(rowMarks);
+	COPY_NODE_FIELD(relationOids);
 	COPY_SCALAR_FIELD(nParamExec);
 
 	return newnode;

src/backend/nodes/outfuncs.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.314 2007/08/31 01:44:05 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.315 2007/10/11 18:05:27 tgl Exp $
  *
  * NOTES
  *	  Every node type that can appear in stored rules' parsetrees *must*
@@ -250,6 +250,7 @@ _outPlannedStmt(StringInfo str, PlannedStmt *node)
 	WRITE_BITMAPSET_FIELD(rewindPlanIDs);
 	WRITE_NODE_FIELD(returningLists);
 	WRITE_NODE_FIELD(rowMarks);
+	WRITE_NODE_FIELD(relationOids);
 	WRITE_INT_FIELD(nParamExec);
 }
 
@@ -1300,6 +1301,7 @@ _outPlannerGlobal(StringInfo str, PlannerGlobal *node)
 	WRITE_NODE_FIELD(subrtables);
 	WRITE_BITMAPSET_FIELD(rewindPlanIDs);
 	WRITE_NODE_FIELD(finalrtable);
+	WRITE_NODE_FIELD(relationOids);
 }
 
 static void

src/backend/optimizer/plan/planner.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.222 2007/09/20 17:56:31 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.223 2007/10/11 18:05:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -134,6 +134,7 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 	glob->subrtables = NIL;
 	glob->rewindPlanIDs = NULL;
 	glob->finalrtable = NIL;
+	glob->relationOids = NIL;
 	glob->transientPlan = false;
 
 	/* Determine what fraction of the plan is likely to be scanned */
@@ -194,6 +195,7 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 	result->rewindPlanIDs = glob->rewindPlanIDs;
 	result->returningLists = root->returningLists;
 	result->rowMarks = parse->rowMarks;
+	result->relationOids = glob->relationOids;
 	result->nParamExec = list_length(glob->paramlist);
 
 	return result;
@@ -1184,7 +1186,8 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 		List	   *rlist;
 
 		Assert(parse->resultRelation);
-		rlist = set_returning_clause_references(parse->returningList,
+		rlist = set_returning_clause_references(root->glob,
+												parse->returningList,
 												result_plan,
 												parse->resultRelation);
 		root->returningLists = list_make1(rlist);

src/backend/utils/cache/plancache.c

@@ -33,7 +33,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/cache/plancache.c,v 1.11 2007/09/20 17:56:31 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/cache/plancache.c,v 1.12 2007/10/11 18:05:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -921,26 +921,17 @@ PlanCacheCallback(Datum arg, Oid relid)
 			foreach(lc2, plan->stmt_list)
 			{
 				PlannedStmt *plannedstmt = (PlannedStmt *) lfirst(lc2);
-				ListCell   *lc3;
 
 				Assert(!IsA(plannedstmt, Query));
 				if (!IsA(plannedstmt, PlannedStmt))
 					continue;			/* Ignore utility statements */
-				foreach(lc3, plannedstmt->rtable)
+				if ((relid == InvalidOid) ? plannedstmt->relationOids != NIL :
+					list_member_oid(plannedstmt->relationOids, relid))
 				{
-					RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc3);
-
-					if (rte->rtekind != RTE_RELATION)
-						continue;
-					if (relid == rte->relid || relid == InvalidOid)
-					{
-						/* Invalidate the plan! */
-						plan->dead = true;
-						break;		/* out of rangetable scan */
-					}
-				}
-				if (plan->dead)
+					/* Invalidate the plan! */
+					plan->dead = true;
 					break;			/* out of stmt_list scan */
+				}
 			}
 		}
 		else

src/include/nodes/plannodes.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/plannodes.h,v 1.95 2007/09/20 17:56:32 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/plannodes.h,v 1.96 2007/10/11 18:05:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -70,6 +70,8 @@ typedef struct PlannedStmt
 
 	List	   *rowMarks;		/* a list of RowMarkClause's */
 
+	List	   *relationOids;	/* OIDs of relations the plan depends on */
+
 	int			nParamExec;		/* number of PARAM_EXEC Params used */
 } PlannedStmt;
 

src/include/nodes/relation.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.146 2007/09/20 17:56:32 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.147 2007/10/11 18:05:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -72,6 +72,8 @@ typedef struct PlannerGlobal
 
 	List	   *finalrtable;	/* "flat" rangetable for executor */
 
+	List	   *relationOids;	/* OIDs of relations the plan depends on */
+
 	bool		transientPlan;	/* redo plan when TransactionXmin changes? */
 } PlannerGlobal;
 

src/include/optimizer/planmain.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/planmain.h,v 1.102 2007/10/04 20:44:47 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/planmain.h,v 1.103 2007/10/11 18:05:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -96,7 +96,8 @@ extern RestrictInfo *build_implied_join_equality(Oid opno,
 extern Plan *set_plan_references(PlannerGlobal *glob,
 								 Plan *plan,
 								 List *rtable);
-extern List *set_returning_clause_references(List *rlist,
+extern List *set_returning_clause_references(PlannerGlobal *glob,
+								List *rlist,
 								Plan *topplan,
 								Index resultRelation);
 extern void fix_opfuncids(Node *node);

src/test/regress/expected/plancache.out

@@ -202,3 +202,20 @@ drop schema s1 cascade;
 NOTICE:  drop cascades to table s1.abc
 drop schema s2 cascade;
 NOTICE:  drop cascades to table abc
+-- Check that invalidation deals with regclass constants
+create temp sequence seq;
+prepare p2 as select nextval('seq');
+execute p2;
+ nextval 
+---------
+       1
+(1 row)
+
+drop sequence seq;
+create temp sequence seq;
+execute p2;
+ nextval 
+---------
+       1
+(1 row)
+

src/test/regress/sql/plancache.sql

@@ -123,3 +123,17 @@ execute p1;
 
 drop schema s1 cascade;
 drop schema s2 cascade;
+
+-- Check that invalidation deals with regclass constants
+
+create temp sequence seq;
+
+prepare p2 as select nextval('seq');
+
+execute p2;
+
+drop sequence seq;
+
+create temp sequence seq;
+
+execute p2;