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 968b9de..0b17346 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);
 }