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From Andrey Mashenkov <andrey.mashen...@gmail.com>
Subject Re: GroupBy with index is really slow.
Date Wed, 10 May 2017 17:50:46 GMT
Hi,

I've just think you can achive same result with query without groupBy.
Select distinct age from ..

Does it workable for you?

10 мая 2017 г. 17:56 пользователь "Guillermo Ortiz" <konstt2000@gmail.com>
написал:

> It's my laptop. 16gb, i7.. The collection size it's 5Mill objects (1,2GB)
> and it takes about 30sec.
> I have tried to execute the query with the same collection with and
> without indices with the same time results.
>
> This is a test before to run in the real cluster with 6 nodes of 512Gb and
> 48cores each one. We tried to execute there with a real dataset(22M rows,
> 7gb) but it takes so long that query is aborted.
>
>
> 2017-05-08 12:12 GMT+02:00 Andrey Mashenkov <andrey.mashenkov@gmail.com>:
>
>> Hi,
>>
>> Why do you think query is slow?
>> What its execution time? What is expected time?
>> How many nodes do you use? How much data does cache contains?
>>
>> On Mon, May 8, 2017 at 1:47 AM, Guillermo Ortiz <konstt2000@gmail.com>
>> wrote:
>>
>>> I have a simple cache where I have Person object (id, age and so on..)
>>>
>>> I have created indeces by id and age to try some examples but queries
>>> with "group by" go really slow.
>>>
>>> I'm trying this query:
>>> SELECT age
>>> FROM
>>> PersonWithindex
>>> group by age
>>>
>>>
>>> SELECT
>>>     AGE AS __C0
>>> FROM "personCacheWithIndex".PERSONWITHINDEX
>>>     /* "personCacheWithIndex"."age_idx" */
>>> GROUP BY AGE
>>> /* group sorted */
>>>
>>> SELECT
>>>     __C0 AS AGE
>>> FROM PUBLIC.__T0
>>>     /* "personCacheWithIndex"."merge_scan" */
>>> GROUP BY __C0
>>>
>>> Although it seems that it uses index, why is it going so slow? I think
>>> that it should be pretty fast with an index.
>>>
>>
>>
>>
>> --
>> Best regards,
>> Andrey V. Mashenkov
>>
>
>

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