@Override
  public boolean isFinished() throws Exception {
    if (!finished) {
      finished = !hasNextWithTimer();
    }
    return finished;
  }
Some special data types(like BLOB) cannot use statistics.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/execution/operator/source/AbstractSeriesAggregationScanOperator.java