presto-main/src/main/java/io/prestosql/sql/planner/LocalExecutionPlanner.java/Visitor/visitRemoteSource
class Visitor:        @Override
        public PhysicalOperation visitRemoteSource(RemoteSourceNode node, LocalExecutionPlanContext context)
        {
            if (node.getOrderingScheme().isPresent()) {
                return createMergeSource(node, context);
            }

            return createRemoteSource(node, context);
        }