hack_hack_reverse_append_subpath_list.patch

diff --git a/src/backend/nodes/list.c b/src/backend/nodes/list.c
index 1597b8e8127..cb686691bd9 100644
--- a/src/backend/nodes/list.c
+++ b/src/backend/nodes/list.c
@@ -1655,6 +1655,37 @@ list_copy_deep(const List *oldlist)
 	return newlist;
 }
 
+/*
+ * Reverses the order of 'list' elements in place and returns the input list
+ */
+List *
+list_reverse(List *list)
+{
+	ListCell	   *head;
+	ListCell	   *tail;
+
+	if (list == NIL)
+		return NIL;
+
+	head = &list->elements[0];
+	tail = &list->elements[list->length - 1];
+
+	while (head < tail)
+	{
+		ListCell tmp;
+
+		/* Swap data at the head and tail position */
+		memcpy(&tmp, head, sizeof(ListCell));
+		memcpy(head, tail, sizeof(ListCell));
+		memcpy(tail, &tmp, sizeof(ListCell));
+
+		head++;
+		tail--;
+	}
+
+	return list;
+}
+
 /*
  * Sort a list according to the specified comparator function.
  *
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index 6cc6966b060..a6ca409ac63 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -1523,7 +1523,7 @@ add_paths_to_append_rel(PlannerInfo *root, RelOptInfo *rel,
 	 * if we have zero or one live subpath due to constraint exclusion.)
 	 */
 	if (subpaths_valid)
-		add_path(rel, (Path *) create_append_path(root, rel, subpaths, NIL,
+		add_path(rel, (Path *) create_append_path(root, rel, list_reverse(subpaths), NIL,
 												  NIL, NULL, 0, false,
 												  -1));
 
diff --git a/src/include/nodes/pg_list.h b/src/include/nodes/pg_list.h
index 4d1cdbbcfdd..413549d8c3e 100644
--- a/src/include/nodes/pg_list.h
+++ b/src/include/nodes/pg_list.h
@@ -677,6 +677,8 @@ pg_nodiscard extern List *list_copy_head(const List *oldlist, int len);
 pg_nodiscard extern List *list_copy_tail(const List *oldlist, int nskip);
 pg_nodiscard extern List *list_copy_deep(const List *oldlist);
 
+extern List *list_reverse(List *list);
+
 typedef int (*list_sort_comparator) (const ListCell *a, const ListCell *b);
 extern void list_sort(List *list, list_sort_comparator cmp);