Teach planner about some cases where a restriction clause can be

propagated inside an outer join.  In particular, given
LEFT JOIN ON (A = B) WHERE A = constant, we cannot conclude that
B = constant at the top level (B might be null instead), but we
can nonetheless put a restriction B = constant into the quals for
B's relation, since no inner-side rows not meeting that condition
can contribute to the final result.  Similarly, given
FULL JOIN USING (J) WHERE J = constant, we can't directly conclude
that either input J variable = constant, but it's OK to push such
quals into each input rel.  Per recent gripe from Kim Bisgaard.
Along the way, remove 'valid_everywhere' flag from RestrictInfo,
as on closer analysis it was not being used for anything, and was
defined backwards anyway.

2 files changed, 13 insertions, 11 deletions

diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index 0a2ca0e5f33..2f906c6a472 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.115 2005/06/13 23:14:49 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.116 2005/07/02 23:00:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -87,6 +87,15 @@ typedef struct PlannerInfo
 	List	   *equi_key_list;	/* list of lists of equijoined
 								 * PathKeyItems */
 
+	List	   *left_join_clauses;	/* list of RestrictInfos for outer join
+									 * clauses w/nonnullable var on left */
+
+	List	   *right_join_clauses;	/* list of RestrictInfos for outer join
+									 * clauses w/nonnullable var on right */
+
+	List	   *full_join_clauses;	/* list of RestrictInfos for full outer
+									 * join clauses */
+
 	List	   *in_info_list;	/* list of InClauseInfos */
 
 	List	   *query_pathkeys; /* desired pathkeys for query_planner(),
@@ -95,6 +104,7 @@ typedef struct PlannerInfo
 	double		tuple_fraction;	/* tuple_fraction passed to query_planner */
 
 	bool		hasJoinRTEs;	/* true if any RTEs are RTE_JOIN kind */
+	bool		hasOuterJoins;	/* true if any RTEs are outer joins */
 	bool		hasHavingQual;	/* true if havingQual was non-null */
 } PlannerInfo;
 
@@ -695,10 +705,6 @@ typedef struct HashPath
  * joined, will also have is_pushed_down set because it will get attached to
  * some lower joinrel.
  *
- * We also store a valid_everywhere flag, which says that the clause is not
- * affected by any lower-level outer join, and therefore any conditions it
- * asserts can be presumed true throughout the plan tree.
- *
  * In general, the referenced clause might be arbitrarily complex.	The
  * kinds of clauses we can handle as indexscan quals, mergejoin clauses,
  * or hashjoin clauses are fairly limited --- the code for each kind of
@@ -725,8 +731,6 @@ typedef struct RestrictInfo
 
 	bool		is_pushed_down; /* TRUE if clause was pushed down in level */
 
-	bool		valid_everywhere;		/* TRUE if valid on every level */
-
 	/*
 	 * This flag is set true if the clause looks potentially useful as a
 	 * merge or hash join clause, that is if it is a binary opclause with
diff --git a/src/include/optimizer/restrictinfo.h b/src/include/optimizer/restrictinfo.h
index 20f51c58204..5a9c2f27224 100644
--- a/src/include/optimizer/restrictinfo.h
+++ b/src/include/optimizer/restrictinfo.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/restrictinfo.h,v 1.31 2005/06/09 04:19:00 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/restrictinfo.h,v 1.32 2005/07/02 23:00:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -19,11 +19,9 @@
 
 extern RestrictInfo *make_restrictinfo(Expr *clause,
 									   bool is_pushed_down,
-									   bool valid_everywhere,
 									   Relids required_relids);
 extern List *make_restrictinfo_from_bitmapqual(Path *bitmapqual,
-											   bool is_pushed_down,
-											   bool valid_everywhere);
+											   bool is_pushed_down);
 extern bool restriction_is_or_clause(RestrictInfo *restrictinfo);
 extern List *get_actual_clauses(List *restrictinfo_list);
 extern void get_actual_join_clauses(List *restrictinfo_list,