Fix another place that wasn't maintaining AND/OR flatness of an

tglsfdc · tglsfdc · commit 67af5bace5df · 2004-01-12T22:20:28.000Z
already-canonicalized qual expression.
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.163 2003/12/28 21:57:36 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.164 2004/01/12 22:20:28 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -380,6 +380,10 @@ preprocess_expression(Query *parse, Node *expr, int kind)
 	 * If it's a qual or havingQual, canonicalize it.  It seems most useful
 	 * to do this before applying eval_const_expressions, since the latter
 	 * can optimize flattened AND/ORs better than unflattened ones.
+	 *
+	 * Note: all processing of a qual expression after this point must be
+	 * careful to maintain AND/OR flatness --- that is, do not generate a
+	 * tree with AND directly under AND, nor OR directly under OR.
 	 */
 	if (kind == EXPRKIND_QUAL)
 	{
@@ -396,14 +400,6 @@ preprocess_expression(Query *parse, Node *expr, int kind)
 	 */
 	expr = eval_const_expressions(expr);
 
-	/*
-	 * If it's a qual or havingQual, convert it to implicit-AND format.
-	 * (We don't want to do this before eval_const_expressions, since the
-	 * latter would be unable to simplify a top-level AND correctly.)
-	 */
-	if (kind == EXPRKIND_QUAL)
-		expr = (Node *) make_ands_implicit((Expr *) expr);
-
 	/* Expand SubLinks to SubPlans */
 	if (parse->hasSubLinks)
 		expr = SS_process_sublinks(expr, (kind == EXPRKIND_QUAL));
@@ -417,6 +413,15 @@ preprocess_expression(Query *parse, Node *expr, int kind)
 	if (PlannerQueryLevel > 1)
 		expr = SS_replace_correlation_vars(expr);
 
+	/*
+	 * If it's a qual or havingQual, convert it to implicit-AND format.
+	 * (We don't want to do this before eval_const_expressions, since the
+	 * latter would be unable to simplify a top-level AND correctly.  Also,
+	 * SS_process_sublinks expects explicit-AND format.)
+	 */
+	if (kind == EXPRKIND_QUAL)
+		expr = (Node *) make_ands_implicit((Expr *) expr);
+
 	return expr;
 }
 
diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/subselect.c,v 1.86 2003/11/29 19:51:50 pgsql Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/subselect.c,v 1.87 2004/01/12 22:20:28 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -848,13 +848,58 @@ process_sublinks_mutator(Node *node, bool *isTopQual)
 	Assert(!IsA(node, Query));
 
 	/*
-	 * If we recurse down through anything other than a List node, we are
-	 * definitely not at top qual level anymore.
+	 * Because make_subplan() could return an AND or OR clause, we have to
+	 * take steps to preserve AND/OR flatness of a qual.  We assume the input
+	 * has been AND/OR flattened and so we need no recursion here.
+	 *
+	 * If we recurse down through anything other than an AND node,
+	 * we are definitely not at top qual level anymore.  (Due to the coding
+	 * here, we will not get called on the List subnodes of an AND, so no
+	 * check is needed for List.)
 	 */
-	if (IsA(node, List))
+	if (and_clause(node))
+	{
+		List   *newargs = NIL;
+		List   *l;
+
+		/* Still at qual top-level */
 		locTopQual = *isTopQual;
-	else
-		locTopQual = false;
+
+		foreach(l, ((BoolExpr *) node)->args)
+		{
+			Node *newarg;
+
+			newarg = process_sublinks_mutator(lfirst(l),
+											  (void *) &locTopQual);
+			if (and_clause(newarg))
+				newargs = nconc(newargs, ((BoolExpr *) newarg)->args);
+			else
+				newargs = lappend(newargs, newarg);
+		}
+		return (Node *) make_andclause(newargs);
+	}
+
+	/* otherwise not at qual top-level */
+	locTopQual = false;
+
+	if (or_clause(node))
+	{
+		List   *newargs = NIL;
+		List   *l;
+
+		foreach(l, ((BoolExpr *) node)->args)
+		{
+			Node *newarg;
+
+			newarg = process_sublinks_mutator(lfirst(l),
+											  (void *) &locTopQual);
+			if (or_clause(newarg))
+				newargs = nconc(newargs, ((BoolExpr *) newarg)->args);
+			else
+				newargs = lappend(newargs, newarg);
+		}
+		return (Node *) make_orclause(newargs);
+	}
 
 	return expression_tree_mutator(node,
 								   process_sublinks_mutator,
