In a nestloop inner indexscan, it's OK to use pushed-down baserestrictinfo

clauses even if it's an outer join.  This is a corner case since such
clauses could only arise from weird OUTER JOIN ON conditions, but worth
fixing.  Per example from Ron at cheapcomplexdevices.com.

diff --git a/src/backend/optimizer/path/indxpath.c b/src/backend/optimizer/path/indxpath.c
index c74e530e2b7af8d15a49378604f16a321dc14a9f..159960764fb4693d4df7b93ac8c5ae271ff54d48 100644 (file)
--- a/src/backend/optimizer/path/indxpath.c
+++ b/src/backend/optimizer/path/indxpath.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/optimizer/path/indxpath.c,v 1.195 2005/11/30 17:10:19 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/optimizer/path/indxpath.c,v 1.196 2005/12/06 16:50:36 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1357,27 +1357,9 @@ find_clauses_for_join(PlannerInfo *root, RelOptInfo *rel,
                      Relids outer_relids, bool isouterjoin)
 {
    List       *clause_list = NIL;
-   bool        jfound = false;
    Relids      join_relids;
    ListCell   *l;
 
-   /*
-    * We can always use plain restriction clauses for the rel.  We scan these
-    * first because we want them first in the clause list for the convenience
-    * of remove_redundant_join_clauses, which can never remove non-join
-    * clauses and hence won't be able to get rid of a non-join clause if it
-    * appears after a join clause it is redundant with.
-    */
-   foreach(l, rel->baserestrictinfo)
-   {
-       RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
-
-       /* Can't use pushed-down clauses in outer join */
-       if (isouterjoin && rinfo->is_pushed_down)
-           continue;
-       clause_list = lappend(clause_list, rinfo);
-   }
-
    /* Look for joinclauses that are usable with given outer_relids */
    join_relids = bms_union(rel->relids, outer_relids);
 
@@ -1385,22 +1367,30 @@ find_clauses_for_join(PlannerInfo *root, RelOptInfo *rel,
    {
        RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
 
-       /* Can't use pushed-down clauses in outer join */
+       /* Can't use pushed-down join clauses in outer join */
        if (isouterjoin && rinfo->is_pushed_down)
            continue;
        if (!bms_is_subset(rinfo->required_relids, join_relids))
            continue;
 
        clause_list = lappend(clause_list, rinfo);
-       jfound = true;
    }
 
    bms_free(join_relids);
 
    /* if no join clause was matched then forget it, per comments above */
-   if (!jfound)
+   if (clause_list == NIL)
        return NIL;
 
+   /*
+    * We can also use any plain restriction clauses for the rel.  We put
+    * these at the front of the clause list for the convenience of
+    * remove_redundant_join_clauses, which can never remove non-join clauses
+    * and hence won't be able to get rid of a non-join clause if it appears
+    * after a join clause it is redundant with.
+    */
+   clause_list = list_concat(list_copy(rel->baserestrictinfo), clause_list);
+
    /*
     * We may now have clauses that are known redundant.  Get rid of 'em.
     */