presto-main/src/main/java/io/prestosql/sql/planner/LocalExecutionPlanner.java/LocalExecutionPlanner/visitUnion
class LocalExecutionPlanner:        @Override
        public PhysicalOperation visitUnion(UnionNode node, LocalExecutionPlanContext context)
        {
            throw new UnsupportedOperationException("Union node should not be present in a local execution plan");
        }