3 files changed, 12 insertions, 5 deletions
diff --git a/src/backend/executor/nodeGatherMerge.c b/src/backend/executor/nodeGatherMerge.c
index ee98f4cf30c..9b4d12b90ef 100644
--- a/src/backend/executor/nodeGatherMerge.c
+++ b/src/backend/executor/nodeGatherMerge.c
@@ -756,7 +756,10 @@ heap_compare_slots(Datum a, Datum b, void *arg)
 									  datum2, isNull2,
 									  sortKey);
 		if (compare != 0)
-			return -compare;
+		{
+			INVERT_COMPARE_RESULT(compare);
+			return compare;
+		}
 	}
 	return 0;
 }
diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c
index 700d7635f3c..9ccdab6d071 100644
--- a/src/backend/executor/nodeIndexscan.c
+++ b/src/backend/executor/nodeIndexscan.c
@@ -474,9 +474,10 @@ reorderqueue_cmp(const pairingheap_node *a, const pairingheap_node *b,
 	ReorderTuple *rtb = (ReorderTuple *) b;
 	IndexScanState *node = (IndexScanState *) arg;
 
-	return -cmp_orderbyvals(rta->orderbyvals, rta->orderbynulls,
-							rtb->orderbyvals, rtb->orderbynulls,
-							node);
+	/* exchange argument order to invert the sort order */
+	return cmp_orderbyvals(rtb->orderbyvals, rtb->orderbynulls,
+						   rta->orderbyvals, rta->orderbynulls,
+						   node);
 }
 
 /*
diff --git a/src/backend/executor/nodeMergeAppend.c b/src/backend/executor/nodeMergeAppend.c
index 6bf490bd700..391e157727b 100644
--- a/src/backend/executor/nodeMergeAppend.c
+++ b/src/backend/executor/nodeMergeAppend.c
@@ -261,7 +261,10 @@ heap_compare_slots(Datum a, Datum b, void *arg)
 									  datum2, isNull2,
 									  sortKey);
 		if (compare != 0)
-			return -compare;
+		{
+			INVERT_COMPARE_RESULT(compare);
+			return compare;
+		}
 	}
 	return 0;
 }