added a sample udf function for benchmark
added a sample udf function for benchmark

amaliujia/CMUDB-peloton,ranxian/peloton,amaliujia/CMUDB-peloton,larryxiao/peloton,amaliujia/CMUDB-peloton,ranxian/peloton,larryxiao/peloton,ranxian/peloton,amaliujia/CMUDB-peloton,amaliujia/CMUDB-peloton,ranxian/peloton,larryxiao/peloton,larryxiao/peloton,larryxiao/peloton,amaliujia/CMUDB-peloton,larryxiao/peloton,ranxian/peloton,amaliujia/CMUDB-peloton,larryxiao/peloton,ranxian/peloton