Refactor planner's pathkeys data structure to create a separate, explicit

representation of equivalence classes of variables.  This is an extensive
rewrite, but it brings a number of benefits:
* planner no longer fails in the presence of "incomplete" operator families
that don't offer operators for every possible combination of datatypes.
* avoid generating and then discarding redundant equality clauses.
* remove bogus assumption that derived equalities always use operators
named "=".
* mergejoins can work with a variety of sort orders (e.g., descending) now,
instead of tying each mergejoinable operator to exactly one sort order.
* better recognition of redundant sort columns.
* can make use of equalities appearing underneath an outer join.

1 files changed, 9 insertions, 35 deletions

diff --git a/src/backend/optimizer/util/joininfo.c b/src/backend/optimizer/util/joininfo.c
index 2971282bf3f..e58903c5d0a 100644
--- a/src/backend/optimizer/util/joininfo.c
+++ b/src/backend/optimizer/util/joininfo.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/joininfo.c,v 1.46 2007/01/05 22:19:32 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/joininfo.c,v 1.47 2007/01/20 20:45:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -16,6 +16,7 @@
 
 #include "optimizer/joininfo.h"
 #include "optimizer/pathnode.h"
+#include "optimizer/paths.h"
 
 
 /*
@@ -55,6 +56,13 @@ have_relevant_joinclause(PlannerInfo *root,
 	}
 
 	/*
+	 * We also need to check the EquivalenceClass data structure, which
+	 * might contain relationships not emitted into the joininfo lists.
+	 */
+	if (!result && rel1->has_eclass_joins && rel2->has_eclass_joins)
+		result = have_relevant_eclass_joinclause(root, rel1, rel2);
+
+	/*
 	 * It's possible that the rels correspond to the left and right sides
 	 * of a degenerate outer join, that is, one with no joinclause mentioning
 	 * the non-nullable side.  The above scan will then have failed to locate
@@ -124,37 +132,3 @@ add_join_clause_to_rels(PlannerInfo *root,
 	}
 	bms_free(tmprelids);
 }
-
-/*
- * remove_join_clause_from_rels
- *	  Delete 'restrictinfo' from all the joininfo lists it is in
- *
- * This reverses the effect of add_join_clause_to_rels.  It's used when we
- * discover that a join clause is redundant.
- *
- * 'restrictinfo' describes the join clause
- * 'join_relids' is the list of relations participating in the join clause
- *				 (there must be more than one)
- */
-void
-remove_join_clause_from_rels(PlannerInfo *root,
-							 RestrictInfo *restrictinfo,
-							 Relids join_relids)
-{
-	Relids		tmprelids;
-	int			cur_relid;
-
-	tmprelids = bms_copy(join_relids);
-	while ((cur_relid = bms_first_member(tmprelids)) >= 0)
-	{
-		RelOptInfo *rel = find_base_rel(root, cur_relid);
-
-		/*
-		 * Remove the restrictinfo from the list.  Pointer comparison is
-		 * sufficient.
-		 */
-		Assert(list_member_ptr(rel->joininfo, restrictinfo));
-		rel->joininfo = list_delete_ptr(rel->joininfo, restrictinfo);
-	}
-	bms_free(tmprelids);
-}