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 <zhtsh.lichao@gmail.com>:
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 <shaofengshi@apache.org>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 <zhaotianshuo@meizu.com>:
ok,I'll have a try


赵天烁

Kevin Zhao

zhaotianshuo@meizu.com

 

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

 
Date: 2016-08-08 17:59
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 <zhaotianshuo@meizu.com>:
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

zhaotianshuo@meizu.com

 

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

 
Date: 2016-08-08 11:32
To: user
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 <zhaotianshuo@meizu.com>:
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

zhaotianshuo@meizu.com

 

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