ERROR: comparetup_datum() should not be called

hi,

commit 337b6f5ecf05b21b5e997986884d097d60e4e3d0 marked comparetup_datum
"should not be called" but actually it is called for eg. tape-based sort.

a testcase:
select generate_series(1,1000000) a into t;
set maintenance_work_mem=1024;
create index concurrently i on t (a);

YAMAMOTO Takashi

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index d8e5d68..ea8eca6 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -3243,9 +3243,9 @@ reversedirection_index_hash(Tuplesortstate *state)
 static int
 comparetup_datum(const SortTuple *a, const SortTuple *b, Tuplesortstate *state)
 {
-	/* Not currently needed */
-	elog(ERROR, "comparetup_datum() should not be called");
-	return 0;
+	return ApplySortComparator(a->datum1, a->isnull1,
+							   b->datum1, b->isnull1,
+							   state->onlyKey);
 }

static void