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;