@Override
    public String toString() {
      StringBuilder builder = new StringBuilder();
      builder.append("CompactorInputSplit{base: ");
      builder.append(base);
      builder.append(", bucket: ");
      builder.append(bucketNum);
      builder.append(", length: ");
      builder.append(length);
      builder.append(", deltas: [");
      for(int i=0; i < deltas.length; ++i) {
        if (i != 0) {
          builder.append(", ");
        }
        builder.append(deltas[i].getName());
      }
      builder.append("]}");
      return builder.toString();
    }
@param hadoopConf
@param bucket bucket to be processed by this split
@param files actual files this split should process.  It is assumed the caller has already
             parsed out the files in base and deltas to populate this list.  Includes copy_N
@param base directory of the base, or the partition/table location if the files are in old
            style.  Can be null.
@param deltas directories of the delta files.
@throws IOException
ql/src/java/org/apache/hadoop/hive/ql/txn/compactor/MRCompactor.java