@Override
  public String[] getMasterKeys() {
    LOG.debug("Begin executing getMasterKeys");
    boolean committed = false;
    Query query = null;
    List<MMasterKey> keys;
    try {
      openTransaction();
      query = pm.newQuery(MMasterKey.class);
      keys = (List<MMasterKey>) query.execute();
      pm.retrieveAll(keys);
      committed = commitTransaction();

      String[] masterKeys = new String[keys.size()];
      for (int i = 0; i < keys.size(); i++) {
        masterKeys[i] = keys.get(i).getMasterKey();
      }
      return masterKeys;
    } finally {
      LOG.debug("Done executing getMasterKeys with status : {}", committed);
      rollbackAndCleanup(committed, query);
    }
  }
Get partition's column stats

@return Map of column name and its stats
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/ObjectStore.java