public byte[] getHistogram() {
    // workaround for DN bug in persisting nulls in pg bytea column instead set empty histogram.
    // https://issues.apache.org/jira/browse/HIVE-17836
    if (histogram != null && histogram.length == 0) {
      return null;
    }
    return histogram;
  }
MTableColumnStatistics - Represents Hive's Column Statistics Description. The fields in this
class with the exception of table are persisted in the metastore. In case of table, tbl_id is
persisted in its place.
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/model/MTableColumnStatistics.java