code: protected void setBigJoin(String[] masterLabels, String masterColumn,
                                String dataColumn, List<String> masterData) {
          setBigJoin(masterLabels, masterColumn, dataColumn, null, masterData);
      }
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 masterData master data