private boolean initialize(String type) {
    ClassLoader classLoader = Utilities.getSessionSpecifiedClassLoader();
    try {
      StatDB statDB = StatDB.valueOf(type);
      publisherImplementation = (Class<? extends Serializable>)
          Class.forName(statDB.getPublisher(jobConf), true, classLoader);
      aggregatorImplementation = (Class<? extends Serializable>)
          Class.forName(statDB.getAggregator(jobConf), true, classLoader);
    } catch (Exception e) {
      LOG.error(type + " Publisher/Aggregator classes cannot be loaded.", e);
      return false;
    }
    return true;
  }
Sets the paths of the implementation classes of publishing
and aggregation (IStatsPublisher and IStatsAggregator interfaces).
The paths are determined according to a configuration parameter which
is passed as the user input for choosing the implementation as MySQL, HBase, ...
ql/src/java/org/apache/hadoop/hive/ql/stats/StatsFactory.java