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