@Override
  public String toString() {
    return String.format(
        "SeriesSchemaFetchScanNode-%s:[StorageGroup: %s, DataRegion: %s]",
        this.getPlanNodeId(),
        storageGroup,
        PlanNodeUtil.printRegionReplicaSet(getRegionReplicaSet()));
  }
This class defines the scan task of schema fetcher.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/planner/plan/node/metadata/read/SeriesSchemaFetchScanNode.java