Only call topn when having_filters don't exist (#2075)
Only call topn when having_filters don't exist (#2075)


timifasubaa/incubator-superset,alanmcruickshank/superset-dev,robert-digit/superset,dmigo/incubator-superset,dmigo/incubator-superset,SingTel-DataCo/incubator-superset,FrederichCheng/incubator-superset,apache/incubator-superset,massgov/incubator-superset,airbnb/caravel,apache/incubator-superset,apache/incubator-superset,FrederichCheng/incubator-superset,ArijanaBrlek/superset,robert-digit/superset,zhouyao1994/incubator-superset,ArijanaBrlek/superset,mistercrunch/panoramix,SingTel-DataCo/incubator-superset,asdf2014/superset,timifasubaa/incubator-superset,alanmcruickshank/superset-dev,airbnb/caravel,asdf2014/superset,alanmcruickshank/superset-dev,robert-digit/superset,airbnb/superset,nekia/incubator-superset-dev,FrederichCheng/incubator-superset,SingTel-DataCo/incubator-superset,zhouyao1994/incubator-superset,airbnb/superset,timifasubaa/incubator-superset,asdf2014/superset,zhouyao1994/incubator-superset,apache/incubator-superset,nekia/incubator-superset-dev,airbnb/superset,massgov/incubator-superset,airbnb/superset,SingTel-DataCo/incubator-superset,nekia/incubator-superset-dev,BRD-CD/superset,robert-digit/superset,mistercrunch/panoramix,mistercrunch/panoramix,apache/incubator-superset,airbnb/caravel,timifasubaa/incubator-superset,dmigo/incubator-superset,ArijanaBrlek/superset,nekia/incubator-superset-dev,FrederichCheng/incubator-superset,dmigo/incubator-superset,alanmcruickshank/superset-dev,BRD-CD/superset,ArijanaBrlek/superset,massgov/incubator-superset,BRD-CD/superset,zhouyao1994/incubator-superset,asdf2014/superset,airbnb/caravel,mistercrunch/panoramix,zhouyao1994/incubator-superset,BRD-CD/superset,massgov/incubator-superset