@Override
  public List<String> getOutputColumnNames() {
    return children.stream()
        .map(PlanNode::getOutputColumnNames)
        .flatMap(List::stream)
        .collect(Collectors.toList());
  }
Responsible for creating ShuffleHelperOperator and corresponding SinkHandle
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/planner/plan/node/sink/ShuffleSinkNode.java