@Override
    public java.sql.Date read(Kryo kryo, Input input, Class<? extends java.sql.Date> clazz) {
      return new java.sql.Date(input.readLong());
    }
Custom Kryo serializer for sql date, otherwise Kryo gets confused between
java.sql.Date and java.util.Date while deserializing
ql/src/java/org/apache/hadoop/hive/ql/exec/SerializationUtilities.java