public boolean isNullValue(int unsortedRowIndex, int columnIndex) {
    if (unsortedRowIndex >= rowCount) {
      return false;
    }
    if (allValueColDeletedMap != null && allValueColDeletedMap.isMarked(unsortedRowIndex)) {
      return true;
    }

    if (columnIndex < 0 || columnIndex >= values.size() || values.get(columnIndex) == null) {
      return true;
    }
    if (bitMaps == null
        || bitMaps.get(columnIndex) == null
        || bitMaps.get(columnIndex).get(unsortedRowIndex / ARRAY_SIZE) == null) {
      return false;
    }
    int arrayIndex = unsortedRowIndex / ARRAY_SIZE;
    int elementIndex = unsortedRowIndex % ARRAY_SIZE;
    List<BitMap> columnBitMaps = bitMaps.get(columnIndex);
    return columnBitMaps.get(arrayIndex).isMarked(elementIndex);
  }
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