Fix for bug #795: two clauses that seem redundant are not really, if

one is pushed down into an outer join and the other is not.

diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c
index 49e2f1f0a2d8cd28fe69f96cb9526d1a62f1e265..a07a208ecfffa5226b309503ec8984ba965c2069 100644 (file)
--- a/src/backend/optimizer/util/relnode.c
+++ b/src/backend/optimizer/util/relnode.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.39 2002/09/04 20:31:22 momjian Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.40 2002/10/12 22:24:49 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -28,7 +28,8 @@ static List *new_join_tlist(List *tlist, int first_resdomno);
 static List *build_joinrel_restrictlist(Query *root,
                           RelOptInfo *joinrel,
                           RelOptInfo *outer_rel,
-                          RelOptInfo *inner_rel);
+                          RelOptInfo *inner_rel,
+                          JoinType jointype);
 static void build_joinrel_joinlist(RelOptInfo *joinrel,
                       RelOptInfo *outer_rel,
                       RelOptInfo *inner_rel);
@@ -334,7 +335,8 @@ build_join_rel(Query *root,
            *restrictlist_ptr = build_joinrel_restrictlist(root,
                                                           joinrel,
                                                           outer_rel,
-                                                          inner_rel);
+                                                          inner_rel,
+                                                          jointype);
        return joinrel;
    }
 
@@ -419,7 +421,8 @@ build_join_rel(Query *root,
    restrictlist = build_joinrel_restrictlist(root,
                                              joinrel,
                                              outer_rel,
-                                             inner_rel);
+                                             inner_rel,
+                                             jointype);
    if (restrictlist_ptr)
        *restrictlist_ptr = restrictlist;
    build_joinrel_joinlist(joinrel, outer_rel, inner_rel);
@@ -508,6 +511,7 @@ new_join_tlist(List *tlist,
  * 'joinrel' is a join relation node
  * 'outer_rel' and 'inner_rel' are a pair of relations that can be joined
  *     to form joinrel.
+ * 'jointype' is the type of join used.
  *
  * build_joinrel_restrictlist() returns a list of relevant restrictinfos,
  * whereas build_joinrel_joinlist() stores its results in the joinrel's
@@ -522,7 +526,8 @@ static List *
 build_joinrel_restrictlist(Query *root,
                           RelOptInfo *joinrel,
                           RelOptInfo *outer_rel,
-                          RelOptInfo *inner_rel)
+                          RelOptInfo *inner_rel,
+                          JoinType jointype)
 {
    List       *result = NIL;
    List       *rlist;
@@ -553,6 +558,11 @@ build_joinrel_restrictlist(Query *root,
     * one clause that checks equality between any set member on the left
     * and any member on the right; by transitivity, all the rest are then
     * equal.
+    *
+    * Weird special case: if we have two clauses that seem redundant
+    * except one is pushed down into an outer join and the other isn't,
+    * then they're not really redundant, because one constrains the
+    * joined rows after addition of null fill rows, and the other doesn't.
     */
    foreach(item, rlist)
    {
@@ -576,7 +586,9 @@ build_joinrel_restrictlist(Query *root,
 
                if (oldrinfo->mergejoinoperator != InvalidOid &&
                    rinfo->left_pathkey == oldrinfo->left_pathkey &&
-                   rinfo->right_pathkey == oldrinfo->right_pathkey)
+                   rinfo->right_pathkey == oldrinfo->right_pathkey &&
+                   (rinfo->ispusheddown == oldrinfo->ispusheddown ||
+                    !IS_OUTER_JOIN(jointype)))
                {
                    redundant = true;
                    break;