fix over outputting in merge join
fix over outputting in merge join


Former-commit-id: fe08354da852e22cae2e1ed581c5f2054d391c1f
larryxiao/peloton-1,ranxian/peloton,larryxiao/peloton,larryxiao/peloton-1,ranxian/peloton,omegaga/peloton,larryxiao/peloton,omegaga/peloton,omegaga/peloton,larryxiao/peloton,amaliujia/CMUDB-peloton,amaliujia/CMUDB-peloton,larryxiao/peloton,amaliujia/CMUDB-peloton,ranxian/peloton,amaliujia/CMUDB-peloton,omegaga/peloton,larryxiao/peloton-1,ranxian/peloton,omegaga/peloton,larryxiao/peloton-1,omegaga/peloton,ranxian/peloton,ranxian/peloton,omegaga/peloton,larryxiao/peloton,amaliujia/CMUDB-peloton,larryxiao/peloton-1,larryxiao/peloton,larryxiao/peloton,larryxiao/peloton-1,amaliujia/CMUDB-peloton,larryxiao/peloton-1,amaliujia/CMUDB-peloton