@Override
  public Column[] generate(int positionCount) {
    long[] values = new long[positionCount];
    int index = 0;
    while (index < positionCount && timeRangeIterator.hasNextTimeRange()) {
      // Get the endTime in the timeRange, it's always the maxTime because the ordering in GROUP BY
      // TIME only allows ascending.
      values[index++] = timeRangeIterator.nextTimeRange().getMax();
    }
    return new Column[] {new LongColumn(positionCount, Optional.empty(), values)};
  }
This class is used to generate a time column in INT64 where the value would increase in a way of
sliding-window. It's only designed for group by time now.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/utils/columngenerator/SlidingTimeColumnGenerator.java