Improve sublink pullup code to handle ANY/EXISTS sublinks that are at top

level of a JOIN/ON clause, not only at top level of WHERE.  (However, we
can't do this in an outer join's ON clause, unless the ANY/EXISTS refers
only to the nullable side of the outer join, so that it can effectively
be pushed down into the nullable side.)  Per request from Kevin Grittner.

In passing, fix a bug in the initial implementation of EXISTS pullup:
it would Assert if the EXIST's WHERE clause used a join alias variable.
Since we haven't yet flattened join aliases when this transformation
happens, it's necessary to include join relids in the computed set of
RHS relids.

src/backend/optimizer/plan/initsplan.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.141 2008/08/14 18:47:59 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.142 2008/08/17 01:19:59 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -778,7 +778,9 @@ distribute_qual_to_rels(PlannerInfo *root, Node *clause,
 				root->hasPseudoConstantQuals = true;
 				/* if not below outer join, push it to top of tree */
 				if (!below_outer_join)
-					relids = get_relids_in_jointree((Node *) root->parse->jointree);
+					relids =
+						get_relids_in_jointree((Node *) root->parse->jointree,
+											   false);
 			}
 		}
 	}

src/backend/optimizer/plan/planner.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.241 2008/08/14 18:47:59 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.242 2008/08/17 01:19:59 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -268,14 +268,13 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
 	root->append_rel_list = NIL;
 
 	/*
-	 * Look for ANY and EXISTS SubLinks at the top level of WHERE, and try to
-	 * transform them into joins.  Note that this step only handles SubLinks
-	 * originally at top level of WHERE; if we pull up any subqueries below,
-	 * their SubLinks are processed just before pulling them up.
+	 * Look for ANY and EXISTS SubLinks in WHERE and JOIN/ON clauses, and try
+	 * to transform them into joins.  Note that this step does not descend
+	 * into subqueries; if we pull up any subqueries below, their SubLinks are
+	 * processed just before pulling them up.
 	 */
 	if (parse->hasSubLinks)
-		parse->jointree->quals = pull_up_sublinks(root,
-												  parse->jointree->quals);
+		pull_up_sublinks(root);
 
 	/*
 	 * Scan the rangetable for set-returning functions, and inline them

src/include/optimizer/prep.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/prep.h,v 1.61 2008/08/14 18:48:00 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/prep.h,v 1.62 2008/08/17 01:20:00 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -21,12 +21,12 @@
 /*
  * prototypes for prepjointree.c
  */
-extern Node *pull_up_sublinks(PlannerInfo *root, Node *node);
+extern void pull_up_sublinks(PlannerInfo *root);
 extern void inline_set_returning_functions(PlannerInfo *root);
 extern Node *pull_up_subqueries(PlannerInfo *root, Node *jtnode,
 				   bool below_outer_join, bool append_rel_member);
 extern void reduce_outer_joins(PlannerInfo *root);
-extern Relids get_relids_in_jointree(Node *jtnode);
+extern Relids get_relids_in_jointree(Node *jtnode, bool include_joins);
 extern Relids get_relids_for_join(PlannerInfo *root, int joinrelid);
 
 /*

src/include/optimizer/subselect.h

@@ -5,7 +5,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/subselect.h,v 1.32 2008/08/14 18:48:00 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/subselect.h,v 1.33 2008/08/17 01:20:00 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -15,9 +15,13 @@
 #include "nodes/plannodes.h"
 #include "nodes/relation.h"
 
-extern Node *convert_ANY_sublink_to_join(PlannerInfo *root, SubLink *sublink);
-extern Node *convert_EXISTS_sublink_to_join(PlannerInfo *root,
-											SubLink *sublink, bool under_not);
+extern bool convert_ANY_sublink_to_join(PlannerInfo *root, SubLink *sublink,
+										Relids available_rels,
+										Node **new_qual, List **fromlist);
+extern bool convert_EXISTS_sublink_to_join(PlannerInfo *root, SubLink *sublink,
+										   bool under_not,
+										   Relids available_rels,
+										   Node **new_qual, List **fromlist);
 extern Node *SS_replace_correlation_vars(PlannerInfo *root, Node *expr);
 extern Node *SS_process_sublinks(PlannerInfo *root, Node *expr, bool isQual);
 extern void SS_finalize_plan(PlannerInfo *root, Plan *plan,