Use a virtual rather than a heap slot in two places where that suffices.

Author: Andres Freund
Discussion: https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de

src/backend/executor/execPartition.c

@@ -1009,7 +1009,7 @@ ExecInitPartitionDispatchInfo(PartitionTupleRouting *proute, Oid partoid,
 													   tupdesc,
 													   gettext_noop("could not convert row type"));
 		pd->tupslot = pd->tupmap ?
-			MakeSingleTupleTableSlot(tupdesc, &TTSOpsHeapTuple) : NULL;
+			MakeSingleTupleTableSlot(tupdesc, &TTSOpsVirtual) : NULL;
 	}
 	else
 	{

src/backend/replication/logical/worker.c

@@ -591,7 +591,7 @@ apply_handle_insert(StringInfo s)
 	estate = create_estate_for_relation(rel);
 	remoteslot = ExecInitExtraTupleSlot(estate,
 										RelationGetDescr(rel->localrel),
-										&TTSOpsHeapTuple);
+										&TTSOpsVirtual);
 
 	/* Input functions may need an active snapshot, so get one */
 	PushActiveSnapshot(GetTransactionSnapshot());