@Override
      public int estimate() {
        JavaDataModel model = JavaDataModel.get();
        return super.estimate() + model.primitive2() * 2;
      }
GenericUDAFTimestampStatsEvaluator
High/low value will be saved in stats DB as long value representing seconds since epoch.
ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDAFComputeStats.java