@Override
  public int compareTo(WALKey o) {
    int result = Bytes.compareTo(this.encodedRegionName, o.getEncodedRegionName());
    if (result == 0) {
      long sid = getSequenceId();
      long otherSid = o.getSequenceId();
      if (sid < otherSid) {
        result = -1;
      } else if (sid > otherSid) {
        result = 1;
      }
      if (result == 0) {
        if (this.writeTime < o.getWriteTime()) {
          result = -1;
        } else if (this.writeTime > o.getWriteTime()) {
          return 1;
        }
      }
    }
    // why isn't cluster id accounted for?
    return result;
  }
@return the cluster id on which the change has originated. It there is no such cluster, it
        returns DEFAULT_CLUSTER_ID (cases where replication is not enabled)
hbase-server/src/main/java/org/apache/hadoop/hbase/wal/WALKeyImpl.java