private List<TSDataType> generateRepeatTsDataType(int size, TSDataType type) {
    List<TSDataType> dataTypes = new ArrayList<>();
    for (int i = 0; i < size; i++) {
      dataTypes.add(type);
    }
    return dataTypes;
  }
Now, we allocate children to each pipeline as average as possible. For example, 5 children with
3 dop, the children group will be [1, 2, 2]. After we can estimate the workload of each
operator, maybe we can allocate based on workload rather than child number.

<p>If child is ExchangeNode, it won't affect the children number of current group.

<p>This method can only be invoked when dop <= localChildrenSize.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/planner/OperatorTreeGenerator.java