skip_calling_sort_tiebreak_when_not_needed2.patch

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 1174e1a31c..12d1bf551b 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -436,7 +436,10 @@ struct Tuplesortstate
 
 	/*
 	 * This variable is shared by the single-key MinimalTuple case and the
-	 * Datum case (which both use qsort_ssup()).  Otherwise it's NULL.
+	 * Datum case (which both use qsort_ssup()).  It is also used by various
+	 * sort specialization functions when comparing the leading key in a
+	 * tiebreak situation to determine if there are any subsequent keys to
+	 * sort on. It's otherwise NULL.
 	 */
 	SortSupport onlyKey;
 
@@ -698,7 +701,12 @@ qsort_tuple_unsigned_compare(SortTuple *a, SortTuple *b, Tuplesortstate *state)
 	compare = ApplyUnsignedSortComparator(a->datum1, a->isnull1,
 										  b->datum1, b->isnull1,
 										  &state->sortKeys[0]);
-	if (compare != 0)
+
+	/*
+	 * No need to call the tiebreak function when the datums differ or if this
+	 * is the only key we're sorting on.
+	 */
+	if (compare != 0 || state->onlyKey != NULL)
 		return compare;
 
 	return state->comparetup(a, b, state);
@@ -713,7 +721,12 @@ qsort_tuple_signed_compare(SortTuple *a, SortTuple *b, Tuplesortstate *state)
 	compare = ApplySignedSortComparator(a->datum1, a->isnull1,
 										b->datum1, b->isnull1,
 										&state->sortKeys[0]);
-	if (compare != 0)
+
+	/*
+	 * No need to call the tiebreak function when the datums differ or if this
+	 * is the only key we're sorting on.
+	 */
+	if (compare != 0 || state->onlyKey != NULL)
 		return compare;
 
 	return state->comparetup(a, b, state);
@@ -728,7 +741,12 @@ qsort_tuple_int32_compare(SortTuple *a, SortTuple *b, Tuplesortstate *state)
 	compare = ApplyInt32SortComparator(a->datum1, a->isnull1,
 										b->datum1, b->isnull1,
 										&state->sortKeys[0]);
-	if (compare != 0)
+
+	/*
+	 * No need to call the tiebreak function when the datums differ or if this
+	 * is the only key we're sorting on.
+	 */
+	if (compare != 0 || state->onlyKey != NULL)
 		return compare;
 
 	return state->comparetup(a, b, state);