v2-0005-Document-find_em_expr_usable_for_sorting_rel-in-p.patch

From dd611ec536f7aef74cea6a64dac1a56dc7cc13ff Mon Sep 17 00:00:00 2001
From: jcoleman <jtc331@gmail.com>
Date: Sun, 29 Nov 2020 09:13:02 -0500
Subject: [PATCH v2 5/5] Document find_em_expr_usable_for_sorting_rel in
 prepare_sort_from_pathkeys

---
 src/backend/optimizer/plan/createplan.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 40abe6f9f6..db31ee6c0f 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -5848,6 +5848,9 @@ make_incrementalsort(Plan *lefttree, int numCols, int nPresortedCols,
  *
  * Returns the node which is to be the input to the Sort (either lefttree,
  * or a Result stacked atop lefttree).
+ *
+ * Note: Restrictions on what expressions are safely sortable may also need to
+ * be added to find_em_expr_usable_for_sorting_rel.
  */
 static Plan *
 prepare_sort_from_pathkeys(Plan *lefttree, List *pathkeys,
-- 
2.17.1