@Override
    protected TimestampObjectInspector getValueObjectInspector(PrimitiveTypeInfo typeInfo) {
      return getValueObjectInspector();
    }
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