Remove the Query structure from the executor's API. This allows us to stop

storing mostly-redundant Query trees in prepared statements, portals, etc.
To replace Query, a new node type called PlannedStmt is inserted by the
planner at the top of a completed plan tree; this carries just the fields of
Query that are still needed at runtime.  The statement lists kept in portals
etc. now consist of intermixed PlannedStmt and bare utility-statement nodes
--- no Query.  This incidentally allows us to remove some fields from Query
and Plan nodes that shouldn't have been there in the first place.

Still to do: simplify the execution-time range table; at the moment the
range table passed to the executor still contains Query trees for subqueries.

initdb forced due to change of stored rules.

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 1.136 2007/02/19 07:03:33 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.137 2007/02/20 17:32:17 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -110,6 +110,10 @@ typedef struct PlannerInfo
 	List	   *join_rel_list;	/* list of join-relation RelOptInfos */
 	struct HTAB *join_rel_hash; /* optional hashtable for join relations */
 
+	List	   *resultRelations;	/* integer list of RT indexes, or NIL */
+
+	List	   *returningLists;		/* list of lists of TargetEntry, or NIL */
+
 	List	   *init_plans;				/* init subplans for query */
 
 	List	   *eq_classes;				/* list of active EquivalenceClasses */