v1-0001-Fix-wrong-unsafe-flag-test-in-check_output_expres.patch

From f03b828a1c95ed86bc682d962c612caaab55eaac Mon Sep 17 00:00:00 2001
From: Richard Guo <guofenglinux@gmail.com>
Date: Mon, 1 Jun 2026 17:12:58 +0900
Subject: [PATCH v1] Fix wrong unsafe-flag test in check_output_expressions()

The check for window functions (point 4) guarded on the wrong bit: it
tested UNSAFE_NOTIN_DISTINCTON_CLAUSE while setting
UNSAFE_NOTIN_PARTITIONBY_CLAUSE.  Each check in this loop guards on
the same bit it is about to set, as an idempotency optimization, since
unsafeFlags[] is accumulated across the arms of a set operation and
there is no point recomputing a column's status once its bit is
present.

This is not a live bug.  When UNSAFE_NOTIN_PARTITIONBY_CLAUSE is
already set but UNSAFE_NOTIN_DISTINCTON_CLAUSE is not, the guard fails
to skip targetIsInAllPartitionLists() and recomputes it, but setting
the same bit again changes nothing.  When
UNSAFE_NOTIN_DISTINCTON_CLAUSE is already set, point 4 is skipped and
UNSAFE_NOTIN_PARTITIONBY_CLAUSE is left unset; but such a column is
already unsafe for pushdown via UNSAFE_NOTIN_DISTINCTON_CLAUSE, so the
outcome is unchanged.  Hence, no backpatch here.

To fix, test UNSAFE_NOTIN_PARTITIONBY_CLAUSE, matching the bit being
set and the pattern of the surrounding checks.
---
 src/backend/optimizer/path/allpaths.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index 61093f222a1..c134594a21a 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -4338,7 +4338,7 @@ check_output_expressions(Query *subquery, pushdown_safety_info *safetyInfo)
 		/* If subquery uses window functions, check point 4 */
 		if (subquery->hasWindowFuncs &&
 			(safetyInfo->unsafeFlags[tle->resno] &
-			 UNSAFE_NOTIN_DISTINCTON_CLAUSE) == 0 &&
+			 UNSAFE_NOTIN_PARTITIONBY_CLAUSE) == 0 &&
 			!targetIsInAllPartitionLists(tle, subquery))
 		{
 			/* not present in all PARTITION BY clauses, so mark it unsafe */
-- 
2.39.5 (Apple Git-154)