code: public SimpleJob setBigJoin(String[] masterLabels, String[] masterColumns,
                                  String[] dataColumns, String masterPath) throws DataFormatException {
          String separator = conf.get(SEPARATOR);
          return setBigJoin(masterLabels, masterColumns, dataColumns, masterPath, separator);
      }
docs: to join the data that does not fit into memory.
  @param masterLabels label of master data
  @param masterColumns master column's
  @param dataColumns data column's
  @param masterPath master data HDFS path
  @return this
  @throws DataFormatException