public final int compareColumns(final Cell left, final Cell right) {
    int diff = compareFamilies(left, right);
    if (diff != 0) {
      return diff;
    }
    return compareQualifiers(left, right);
  }
Compares the family and qualifier part of the cell
@return 0 if both cells are equal, 1 if left cell is bigger than right, -1 otherwise
hbase-common/src/main/java/org/apache/hadoop/hbase/CellComparatorImpl.java