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From ShaoFeng Shi <shaofeng...@apache.org>
Subject Re: Re: does kylin support top-N on a count or count distinct measure?
Date Tue, 09 Aug 2016 04:19:16 GMT
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 <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
>>>
>>>
>>> *From:* Alberto Ramón <a.ramonportoles@gmail.com>
>>> *Date:* 2016-08-08 17:59
>>> *To:* user@kylin.apache.org
>>> *CC:* ShaoFeng Shi <shaofengshi@apache.org>
>>> *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 <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
>>>>
>>>>
>>>> *From:* ShaoFeng Shi <shaofengshi@apache.org>
>>>> *Date:* 2016-08-08 11:32
>>>> *To:* user <user@kylin.apache.org>
>>>> *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 <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

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