nocfbot-0011-define-cost.txt

From 613d2b9cc310f9e55c71ef16555b9c42401c46b9 Mon Sep 17 00:00:00 2001
From: Henson Choi <assam258@gmail.com>
Date: Sun, 1 Mar 2026 19:09:27 +0900
Subject: [PATCH] Add RPR DEFINE expression cost to WindowAgg cost estimation

---
 src/backend/optimizer/path/costsize.c | 29 +++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 89ca4e08bf1..a10fb802d0e 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -103,6 +103,7 @@
 #include "optimizer/placeholder.h"
 #include "optimizer/plancat.h"
 #include "optimizer/restrictinfo.h"
+#include "optimizer/rpr.h"
 #include "parser/parsetree.h"
 #include "utils/lsyscache.h"
 #include "utils/selfuncs.h"
@@ -3227,7 +3228,35 @@ cost_windowagg(Path *path, PlannerInfo *root,
 	 * many rows the window function will fetch, it's hard to do better.  In
 	 * any case, it's a good estimate for all the built-in window functions,
 	 * so we'll just do this for now.
+	 *
+	 * Moreover, if row pattern recognition is used, we charge the DEFINE
+	 * expressions once per tuple for each variable that appears in PATTERN.
 	 */
+	if (winclause->rpPattern)
+	{
+		List	   *pattern_vars;
+		ListCell   *lc2;
+		QualCost	defcosts;
+
+		pattern_vars = collectPatternVariables(winclause->rpPattern);
+
+		foreach(lc2, pattern_vars)
+		{
+			char	   *ptname = strVal(lfirst(lc2));
+
+			foreach_node(TargetEntry, def, winclause->defineClause)
+			{
+				if (!strcmp(ptname, def->resname))
+				{
+					cost_qual_eval_node(&defcosts, (Node *) def->expr, root);
+					startup_cost += defcosts.startup;
+					total_cost += defcosts.per_tuple * input_tuples;
+				}
+			}
+		}
+		list_free_deep(pattern_vars);
+	}
+
 	foreach(lc, windowFuncs)
 	{
 		WindowFunc *wfunc = lfirst_node(WindowFunc, lc);
-- 
2.50.1 (Apple Git-155)