From afaa6b982115ad490326be2c66c577f6195f0067 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 30 Apr 2007 00:14:54 +0000
Subject: [PATCH] Marginal performance hack: avoid unnecessary work in
 expression_tree_mutator. We can just palloc, instead of using makeNode, when
 we are going to overwrite the whole node anyway in the FLATCOPY macro.  Also,
 use FLATCOPY instead of copyObject for common node types Var and Const.

---
 src/backend/optimizer/util/clauses.c | 29 ++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 8b646516de..417cecff8e 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.242 2007/04/27 22:05:48 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.243 2007/04/30 00:14:54 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -3770,12 +3770,12 @@ expression_tree_mutator(Node *node,
 	 */
 
 #define FLATCOPY(newnode, node, nodetype)  \
-	( (newnode) = makeNode(nodetype), \
+	( (newnode) = (nodetype *) palloc(sizeof(nodetype)), \
 	  memcpy((newnode), (node), sizeof(nodetype)) )
 
 #define CHECKFLATCOPY(newnode, node, nodetype)	\
 	( AssertMacro(IsA((node), nodetype)), \
-	  (newnode) = makeNode(nodetype), \
+	  (newnode) = (nodetype *) palloc(sizeof(nodetype)), \
 	  memcpy((newnode), (node), sizeof(nodetype)) )
 
 #define MUTATE(newfield, oldfield, fieldtype)  \
@@ -3789,15 +3789,36 @@ expression_tree_mutator(Node *node,
 
 	switch (nodeTag(node))
 	{
+		/*
+		 * Primitive node types with no expression subnodes.  Var and Const
+		 * are frequent enough to deserve special cases, the others we just
+		 * use copyObject for.
+		 */
 		case T_Var:
+			{
+				Var	   *var = (Var *) node;
+				Var	   *newnode;
+
+				FLATCOPY(newnode, var, Var);
+				return (Node *) newnode;
+			}
+			break;
 		case T_Const:
+			{
+				Const	   *oldnode = (Const *) node;
+				Const	   *newnode;
+
+				FLATCOPY(newnode, oldnode, Const);
+				/* XXX we don't bother with datumCopy; should we? */
+				return (Node *) newnode;
+			}
+			break;
 		case T_Param:
 		case T_CoerceToDomainValue:
 		case T_CaseTestExpr:
 		case T_SetToDefault:
 		case T_RangeTblRef:
 		case T_OuterJoinInfo:
-			/* primitive node types with no expression subnodes */
 			return (Node *) copyObject(node);
 		case T_Aggref:
 			{
-- 
2.40.0