public StatsSource getStatsSource() {
    if (statsSource != null) {
      return statsSource;
    } else {
      // hierarchical; add def stats also here
      return EmptyStatsSource.INSTANCE;
    }
  }
@param isHDFSCleanup the isHDFSCleanup to set
ql/src/java/org/apache/hadoop/hive/ql/Context.java