default int compareRows(byte[] leftRow, byte[] rightRow) {
    return Bytes.compareTo(leftRow, rightRow);
  }
Compares two row bytes
@param leftRow  the byte array of the left row
@param rightRow the byte array of the right row
@return greater than 0 if leftRow is bigger, less than 0 if rightRow is bigger, 0 if both rows
        are equal
hbase-common/src/main/java/org/apache/hadoop/hbase/CellComparator.java