Make sure make_rels_by_clause_joins doesn't return multiple references

to same joinrel.  Although make_rels_by_joins doesn't mind, GEQO has
an Assert that doesn't like this.

diff --git a/src/backend/optimizer/path/joinrels.c b/src/backend/optimizer/path/joinrels.c
index 74cc0365bbd8f9df5ee61091cbfc16d66e17d3a6..17a6288b920a7870efd2ece126d48d22fcde06f6 100644 (file)
--- a/src/backend/optimizer/path/joinrels.c
+++ b/src/backend/optimizer/path/joinrels.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinrels.c,v 1.48 2000/09/29 18:21:32 tgl Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinrels.c,v 1.49 2000/12/18 06:50:51 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -262,9 +262,18 @@ make_rels_by_clause_joins(Query *root,
            RelOptInfo *other_rel = (RelOptInfo *) lfirst(j);
 
            if (is_subseti(unjoined_relids, other_rel->relids))
-               result = lcons(make_join_rel(root, old_rel, other_rel,
-                                            JOIN_INNER),
-                              result);
+           {
+               RelOptInfo *jrel;
+
+               jrel = make_join_rel(root, old_rel, other_rel, JOIN_INNER);
+               /*
+                * Avoid entering same joinrel into our output list more
+                * than once.  (make_rels_by_joins doesn't really care,
+                * but GEQO does.)
+                */
+               if (!ptrMember(jrel, result))
+                   result = lcons(jrel, result);
+           }
        }
    }
 
@@ -297,9 +306,16 @@ make_rels_by_clauseless_joins(Query *root,
        RelOptInfo *other_rel = (RelOptInfo *) lfirst(i);
 
        if (nonoverlap_setsi(other_rel->relids, old_rel->relids))
-           result = lcons(make_join_rel(root, old_rel, other_rel,
-                                        JOIN_INNER),
-                          result);
+       {
+           RelOptInfo *jrel;
+
+           jrel = make_join_rel(root, old_rel, other_rel, JOIN_INNER);
+           /*
+            * As long as given other_rels are distinct, don't need
+            * to test to see if jrel is already part of output list.
+            */
+           result = lcons(jrel, result);
+       }
    }
 
    return result;