private void updateMinTime() {
    long minTime = Long.MAX_VALUE;
    for (int i = 0; i < rowCount; i++) {
      if (!isTimeDeleted(i)) {
        minTime = Math.min(minTime, getTime(i));
      }
    }
    this.minTime = minTime;
  }
Get whether value is null at the given position in AlignedTvList.

@param unsortedRowIndex value index inside this column
@param columnIndex index of the column
@return boolean
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/utils/datastructure/AlignedTVList.java