Quick hack to fix Oliver Elphick's problem with subselects in an

inheritance query: make duplicate copies of subplans in adjust_inherited_attrs.
When we redesign querytrees we really gotta do something about this
issue of whether querytrees are read-only and can share substructure
or not.

diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 968b9ded7801d70cb11425b184af3364a05c4ca2..0b173466cf98061a3add13f850ba9e750dd9f4e0 100644 (file)
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -14,7 +14,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.61 2001/03/22 03:59:38 momjian Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.62 2001/03/27 18:02:19 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -679,7 +679,7 @@ adjust_inherited_attrs_mutator(Node *node,
            adjust_inherited_attrs_mutator((Node *) oldinfo->clause, context);
 
        newinfo->subclauseindices = NIL;
-       newinfo->eval_cost = -1;/* reset this too */
+       newinfo->eval_cost = -1;        /* reset this too */
        newinfo->left_pathkey = NIL;    /* and these */
        newinfo->right_pathkey = NIL;
        newinfo->left_dispersion = -1;
@@ -692,6 +692,29 @@ adjust_inherited_attrs_mutator(Node *node,
     * NOTE: we do not need to recurse into sublinks, because they should
     * already have been converted to subplans before we see them.
     */
+
+   /*
+    * BUT: although we don't need to recurse into subplans, we do need to
+    * make sure that they are copied, not just referenced as
+    * expression_tree_mutator will do by default.  Otherwise we'll have the
+    * same subplan node referenced from each arm of the inheritance APPEND
+    * plan, which will cause trouble in the executor.  This is a kluge
+    * that should go away when we redesign querytrees.
+    */
+   if (is_subplan(node))
+   {
+       SubPlan    *subplan;
+
+       /* Copy the node and process subplan args */
+       node = expression_tree_mutator(node, adjust_inherited_attrs_mutator,
+                                      (void *) context);
+       /* Make sure we have separate copies of subplan and its rtable */
+       subplan = (SubPlan *) ((Expr *) node)->oper;
+       subplan->plan = copyObject(subplan->plan);
+       subplan->rtable = copyObject(subplan->rtable);
+       return node;
+   }
+
    return expression_tree_mutator(node, adjust_inherited_attrs_mutator,
                                   (void *) context);
 }