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From Anil <anilk...@gmail.com>
Subject Re: NOT IN in ignite
Date Tue, 07 Feb 2017 10:37:29 GMT
Hi Andrey,

thanks for response and little confused.

I hope "group" is the entries of two (or more) caches which are collocated
with affinity key. please correct if i am wrong.

"For example: In this case, we can make grouping and apply Having condition on
map stage, that
results in reducing network traffic." - *Agree. no aggregation in reduce
and apply pagination and return to client ? or just return map response to
client ?*

Thanks.


On 7 February 2017 at 14:55, Andrey Mashenkov <andrey.mashenkov@gmail.com>
wrote:

> Hi Anil,
>
> Group by queries with collocate = true will be correct if:
> for every group there is only partition that contains all data of this
> group.
> Ignite does not know if group data is collocated for a query, so with this
> option we can give a hint to Ignite.
>
> For example: In this case, we can make grouping and apply Having condition on
> map stage, that
> results in reducing network traffic.
>
> For non-collocated groups we can't apply Having on map stage as we have
> only part of data at this time.
> So, in this case with collocate = true we can get wrong results.
>
>
>
> On Tue, Feb 7, 2017 at 6:29 AM, Anil <anilklce@gmail.com> wrote:
>
>> Hi,
>>
>> May I know what do you mean by "When used incorrectly" ?
>>
>> group by queries with collocate = true is not incorrect usage or i
>> misunderstood this ?
>>
>> Thanks.
>>
>> On 7 February 2017 at 01:26, vkulichenko <valentin.kulichenko@gmail.com>
>> wrote:
>>
>>> Well, I would agree that the flag is confusing, but your understanding
>>> is not
>>> correct. When used incorrectly, this flag does breaks query result
>>> because
>>> it forces Ignite to change execution plan to more optimal. This
>>> optimization
>>> doesn't always work though (that's actually the reason why it's
>>> configurable).
>>>
>>> -Val
>>>
>>>
>>>
>>> --
>>> View this message in context: http://apache-ignite-users.705
>>> 18.x6.nabble.com/NOT-IN-in-ignite-tp9861p10458.html
>>> Sent from the Apache Ignite Users mailing list archive at Nabble.com.
>>>
>>
>>
>
>
> --
> Best regards,
> Andrey V. Mashenkov
>

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