public void addChildDeviceNode(IDeviceID deviceName, PlanNode childNode) {
    this.devices.add(deviceName);
    this.children.add(childNode);
  }
DeviceViewNode is responsible for constructing a device-based view of a set of series. And output
the result with specific order. The order could be 'order by device' or 'order by timestamp'

<p>Each output from its children should have the same schema. That means, the columns should be
same between these TsBlocks. If the input TsBlock contains n columns, the device-based view will
contain n+1 columns where the new column is Device column.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/planner/plan/node/process/DeviceViewNode.java