@Override
  public int compareTo(RecordIdentifier other) {
    if (other.getClass() != RecordIdentifier.class) {
      //WTF?  assumes that other instanceof OrcRawRecordMerger.ReaderKey???
      return -other.compareTo(this);
    }
    return compareToInternal(other);
  }
What was the original row id for the last row?
@return the row id
ql/src/java/org/apache/hadoop/hive/ql/io/RecordIdentifier.java