Fix failure to set correct operator in window run condition

david-rowley · david-rowley · commit 53823a06be6f · 2022-08-05T10:14:00.000+12:00
This was a simple omission in 9d9c02c where the code didn't correctly set the operator to use in the run condition OpExpr when the window function was both monotonically increasing and decreasing. Bug discovered by Julien Roze, although he did not report it. Reported-by: Phil Florent Discussion: https://postgr.es/m/PA4P191MB160009A09B9D0624359278CFBA9F9@PA4P191MB1600.EURP191.PROD.OUTLOOK.COM Backpatch-through: 15, where 9d9c02c was added
diff --git 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
@@ -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
@@ -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

Original file line number	Diff line number	Diff line change
`@@ -2306,6 +2306,7 @@ find_window_run_conditions(Query subquery, RangeTblEntry rte, Index rti,`
`2306`	`2306`	`{`
`2307`	`2307`	`*keep_original = false;`
`2308`	`2308`	`runopexpr = opexpr;`
	`2309`	`+ runoperator = opexpr->opno;`
`2309`	`2310`	`break;`
`2310`	`2311`	`}`
`2311`	`2312`