Hi Tiansheng, The less post-aggregation, the better query performance; So for a specific query, if the "signle groupby column topN" need further aggregation to get the final result, but "multiple groupby column topN" doesn't, then the later one would have better performance.
I didn't compare that, just personal cents; Welcome to do benchmark and share with the community :-) 2016-08-09 11:54 GMT+08:00 张天生 <[email protected]>: > I have a question: whether multiple column groupby is better performance > than a single column groupby in topN measure. As i known it all can agg > other dimensions. > Whether it there was performance optimization in mulitple column groupby > in topN measure. > > ShaoFeng Shi <[email protected]>于2016年8月8日周一 下午6:20写道： > >> Alberto is correct; SUM(1) and multiple columns are implemented in Kylin >> core, but from UI you couldn't define that; You need manually edit metadata >> for that. >> >> 2016-08-08 18:02 GMT+08:00 赵天烁 <[email protected]>: >> >>> ok,I'll have a try >>> >>> ------------------------------ >>> >>> 赵天烁 >>> >>> Kevin Zhao >>> >>> *[email protected] <[email protected]>* >>> >>> >>> >>> 珠海市魅族科技有限公司 >>> >>> MEIZU Technology Co., Ltd. >>> >>> 广东省珠海市科技创新海岸魅族科技楼 >>> >>> MEIZU Tech Bldg., Technology & Innovation Coast >>> >>> Zhuhai, 519085, Guangdong, China >>> >>> meizu.com >>> >>> >>> *From:* Alberto Ramón <[email protected]> >>> *Date:* 2016-08-08 17:59 >>> *To:* [email protected] >>> *CC:* ShaoFeng Shi <[email protected]> >>> *Subject:* Re: Re: does kylin support top-N on a count or count >>> distinct measure? >>> In teorical en v1.5.3, you can Group by 'n' columns: >>> https://issues.apache.org/jira/browse/KYLIN-1693 >>> >>> I don't tested 1.5.3 yet, and I don't know if has been implemented in UI >>> Kylin, perhaps you can add this columns to JSON manually :) >>> >>> BR, Alberto >>> >>> 2016-08-08 11:37 GMT+02:00 赵天烁 <[email protected]>: >>> >>>> SUM(1)? you mean just left ORDER|SUM by Column empty? ,then another >>>> prob is I can't configure more than one group by column to it,how to walk >>>> around that? >>>> >>>> ------------------------------ >>>> >>>> 赵天烁 >>>> >>>> Kevin Zhao >>>> >>>> *[email protected] <[email protected]>* >>>> >>>> >>>> >>>> 珠海市魅族科技有限公司 >>>> >>>> MEIZU Technology Co., Ltd. >>>> >>>> 广东省珠海市科技创新海岸魅族科技楼 >>>> >>>> MEIZU Tech Bldg., Technology & Innovation Coast >>>> >>>> Zhuhai, 519085, Guangdong, China >>>> >>>> meizu.com >>>> >>>> >>>> *From:* ShaoFeng Shi <[email protected]> >>>> *Date:* 2016-08-08 11:32 >>>> *To:* user <[email protected]> >>>> *Subject:* Re: does kylin support top-N on a count or count distinct >>>> measure? >>>> For sorting on count, you can use SUM(1) as the expression; >>>> >>>> For sorting on other measure, it is on roadmap: https://issues. >>>> apache.org/jira/browse/KYLIN-1377 >>>> >>>> We welcome the community to contribute on such enhancements, anyone >>>> want to have a try? >>>> >>>> 2016-08-05 15:24 GMT+08:00 赵天烁 <[email protected]>: >>>> >>>>> right now top-N measure need to specify a sum column, >>>>> does kylin support top-N on a count or count distinct measure? >>>>> >>>>> ------------------------------ >>>>> >>>>> 赵天烁 >>>>> >>>>> Kevin Zhao >>>>> >>>>> *[email protected] <[email protected]>* >>>>> >>>>> >>>>> >>>>> 珠海市魅族科技有限公司 >>>>> >>>>> MEIZU Technology Co., Ltd. >>>>> >>>>> 广东省珠海市科技创新海岸魅族科技楼 >>>>> >>>>> MEIZU Tech Bldg., Technology & Innovation Coast >>>>> >>>>> Zhuhai, 519085, Guangdong, China >>>>> >>>>> meizu.com >>>>> >>>> >>>> >>>> >>>> -- >>>> Best regards, >>>> >>>> Shaofeng Shi >>>> >>>> >>> >> >> >> -- >> Best regards, >> >> Shaofeng Shi >> >> -- Best regards, Shaofeng Shi
