public OrcTail getOrcTail() {
    return orcTail;
  }
For every split we only want to keep the delete deltas, that contains files for that bucket.
If we filter out files, we might need to filter out statementIds from multistatement transactions.
@param dmd
@param bucketId
@return
ql/src/java/org/apache/hadoop/hive/ql/io/orc/OrcSplit.java