From 81a9b83b9d61704e85d97bc79b10ac6a00d73def Mon Sep 17 00:00:00 2001
From: Henson Choi <assam258@gmail.com>
Date: Wed, 4 Mar 2026 15:53:33 +0900
Subject: [PATCH 5/8] Disable run condition pushdown for RPR windows


diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index 90275e25872..b67c35af39a 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -2453,6 +2453,17 @@ find_window_run_conditions(Query *subquery, AttrNumber attno,
 	wclause = (WindowClause *) list_nth(subquery->windowClause,
 										wfunc->winref - 1);
 
+	/*
+	 * If a DEFINE clause exists, we cannot push down a run condition. In the
+	 * case, a window partition (or frame) is divided into multiple reduced
+	 * frames and each frame should be evaluated to the end of the partition
+	 * (or full frame end). This means we cannot apply the run condition
+	 * optimization because it stops evaluation window functions in certain
+	 * cases.
+	 */
+	if (wclause->defineClause != NIL)
+		return false;
+
 	req.type = T_SupportRequestWFuncMonotonic;
 	req.window_func = wfunc;
 	req.window_clause = wclause;
diff --git a/src/test/regress/expected/rpr_base.out b/src/test/regress/expected/rpr_base.out
index ae6d9c9b937..a7c536625f1 100644
--- a/src/test/regress/expected/rpr_base.out
+++ b/src/test/regress/expected/rpr_base.out
@@ -2465,7 +2465,9 @@ WHERE cnt > 0
 ORDER BY id;
  id | val | cnt 
 ----+-----+-----
-(0 rows)
+  2 |  20 |   2
+  4 |  40 |   1
+(2 rows)
 
 -- Nested subqueries
 SELECT *
-- 
2.50.1 (Apple Git-155)