3 files changed, 29 insertions, 0 deletions
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index b23cc8ee82d..8fc28007f54 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -2306,6 +2306,7 @@ find_window_run_conditions(Query *subquery, RangeTblEntry *rte, Index rti,
 			{
 				*keep_original = false;
 				runopexpr = opexpr;
+				runoperator = opexpr->opno;
 				break;
 			}
 
diff --git a/src/test/regress/expected/window.out b/src/test/regress/expected/window.out
index 433a0bb0259..55dcd668c94 100644
--- a/src/test/regress/expected/window.out
+++ b/src/test/regress/expected/window.out
@@ -3646,6 +3646,23 @@ WHERE c <= 3;
      3 | sales     |   4800 | 3
 (8 rows)
 
+-- Ensure we get the correct run condition when the window function is both
+-- monotonically increasing and decreasing.
+EXPLAIN (COSTS OFF)
+SELECT * FROM
+  (SELECT empno,
+          depname,
+          salary,
+          count(empno) OVER () c
+   FROM empsalary) emp
+WHERE c = 1;
+                       QUERY PLAN                       
+--------------------------------------------------------
+ WindowAgg
+   Run Condition: (count(empsalary.empno) OVER (?) = 1)
+   ->  Seq Scan on empsalary
+(3 rows)
+
 -- Some more complex cases with multiple window clauses
 EXPLAIN (COSTS OFF)
 SELECT * FROM
diff --git a/src/test/regress/sql/window.sql b/src/test/regress/sql/window.sql
index a504e46e403..57c39e796c1 100644
--- a/src/test/regress/sql/window.sql
+++ b/src/test/regress/sql/window.sql
@@ -1150,6 +1150,17 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE c <= 3;
 
+-- Ensure we get the correct run condition when the window function is both
+-- monotonically increasing and decreasing.
+EXPLAIN (COSTS OFF)
+SELECT * FROM
+  (SELECT empno,
+          depname,
+          salary,
+          count(empno) OVER () c
+   FROM empsalary) emp
+WHERE c = 1;
+
 -- Some more complex cases with multiple window clauses
 EXPLAIN (COSTS OFF)
 SELECT * FROM