Suppress subquery pullup and pushdown when the subquery has any

set-returning functions in its target list.  This ensures that we
won't rewrite the query in a way that places set-returning functions
into quals (WHERE clauses).  Cf. bug reports from Joe Conway.

Author: tglsfdc

src/backend/optimizer/path/allpaths.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/allpaths.c,v 1.82 2001/11/05 17:46:25 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/allpaths.c,v 1.83 2001/12/10 22:54:12 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -305,7 +305,14 @@ set_subquery_pathlist(Query *root, RelOptInfo *rel,
 	 * checking that seems more work than it's worth.  In any case, a
 	 * plain DISTINCT is safe to push down past.)
 	 *
-	 * 3. We do not push down clauses that contain subselects, mainly because
+	 * 3. If the subquery has any ITER nodes (ie, functions returning sets)
+	 * in its target list, we do not push down any quals, since the quals
+	 * might refer to those tlist items, which would mean we'd introduce
+	 * functions-returning-sets into the subquery's WHERE/HAVING quals.
+	 * (It'd be sufficient to not push down quals that refer to those
+	 * particular tlist items, but that's much clumsier to check.)
+	 *
+	 * 4. We do not push down clauses that contain subselects, mainly because
 	 * I'm not sure it will work correctly (the subplan hasn't yet
 	 * transformed sublinks to subselects).
 	 *
@@ -318,7 +325,8 @@ set_subquery_pathlist(Query *root, RelOptInfo *rel,
 	if (subquery->setOperations == NULL &&
 		subquery->limitOffset == NULL &&
 		subquery->limitCount == NULL &&
-		!has_distinct_on_clause(subquery))
+		!has_distinct_on_clause(subquery) &&
+		!contain_iter_clause((Node *) subquery->targetList))
 	{
 		/* OK to consider pushing down individual quals */
 		List	   *upperrestrictlist = NIL;

src/backend/optimizer/plan/planner.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.113 2001/11/05 17:46:26 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.114 2001/12/10 22:54:12 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -461,6 +461,15 @@ is_simple_subquery(Query *subquery)
 		subquery->limitCount)
 		return false;
 
+	/*
+	 * Don't pull up a subquery that has any set-returning functions in
+	 * its targetlist.  Otherwise we might well wind up inserting
+	 * set-returning functions into places where they mustn't go,
+	 * such as quals of higher queries.
+	 */
+	if (contain_iter_clause((Node *) subquery->targetList))
+		return false;
+
 	/*
 	 * Hack: don't try to pull up a subquery with an empty jointree.
 	 * query_planner() will correctly generate a Result plan for a

src/backend/optimizer/util/clauses.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.91 2001/11/05 17:46:26 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.92 2001/12/10 22:54:12 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -47,6 +47,7 @@ typedef struct
 
 static bool contain_agg_clause_walker(Node *node, void *context);
 static bool pull_agg_clause_walker(Node *node, List **listptr);
+static bool contain_iter_clause_walker(Node *node, void *context);
 static bool contain_subplans_walker(Node *node, void *context);
 static bool pull_subplans_walker(Node *node, List **listptr);
 static bool check_subplans_for_ungrouped_vars_walker(Node *node,
@@ -450,6 +451,39 @@ pull_agg_clause_walker(Node *node, List **listptr)
 }
 
 
+/*****************************************************************************
+ *		Iter clause manipulation
+ *****************************************************************************/
+
+/*
+ * contain_iter_clause
+ *	  Recursively search for Iter nodes within a clause.
+ *
+ *	  Returns true if any Iter found.
+ *
+ * XXX Iter is a crock.  It'd be better to look directly at each function
+ * or operator to see if it can return a set.  However, that would require
+ * a lot of extra cycles as things presently stand.  The return-type info
+ * for function and operator nodes should be extended to include whether
+ * the return is a set.
+ */
+bool
+contain_iter_clause(Node *clause)
+{
+	return contain_iter_clause_walker(clause, NULL);
+}
+
+static bool
+contain_iter_clause_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Iter))
+		return true;			/* abort the tree traversal and return
+								 * true */
+	return expression_tree_walker(node, contain_iter_clause_walker, context);
+}
+
 /*****************************************************************************
  *		Subplan clause manipulation
  *****************************************************************************/

src/include/optimizer/clauses.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: clauses.h,v 1.49 2001/11/05 17:46:34 momjian Exp $
+ * $Id: clauses.h,v 1.50 2001/12/10 22:54:12 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -42,6 +42,8 @@ extern List *make_ands_implicit(Expr *clause);
 extern bool contain_agg_clause(Node *clause);
 extern List *pull_agg_clause(Node *clause);
 
+extern bool contain_iter_clause(Node *clause);
+
 extern bool contain_subplans(Node *clause);
 extern List *pull_subplans(Node *clause);
 extern void check_subplans_for_ungrouped_vars(Query *query);