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From Zhenya Stanilovsky <arzamas...@mail.ru.INVALID>
Subject Re[4]: [DISCUSSION] Fail on non-colocated join
Date Wed, 03 Feb 2021 13:48:48 GMT


I think it`s « absolutely needed » case ) Many people will find erroneous places.


 
>Hello!
>
>Many people do read logs, especially developers. You would be amazed how
>many people come to discuss even the most benign of warnings.
>
>I think it violates the Apache Ignite compatibility policy, where we do not
>break existing code during a major release.
>
>We do not always hold on to that principle, for example Baseline Topology
>introduced some changes which needed to be explicitly handled by the user.
>But in this case, it looks like a violation.
>
>https://cwiki.apache.org/confluence/display/IGNITE/Review+Checklist
>
>It's checklist, 1b.
>
>Regards,
>--
>Ilya Kasnacheev
>
>
>ср, 3 февр. 2021 г. в 14:48, Zhenya Stanilovsky < arzamas123@mail.ru.invalid
>>:
>
>>
>>
>>
>>
>> >If it breaks existing working code it may not be done that way.
>>
>> Who reads the logs ?
>> Is it violates apache way approach or some existing rules ?
>>
>> thanks !
>>
>>
>> >Regards,
>> >--
>> >Ilya Kasnacheev
>> >
>> >
>> >ср, 3 февр. 2021 г. в 09:05, Zhenya Stanilovsky <
>>  arzamas123@mail.ru.invalid
>> >>:
>> >
>> >>
>> >>
>> >> Maxim it`s cool that it`s moved :)
>> >> +1 for exception, but take into account such use case :
>> >> T1 (country, city) affinity_key=country and T2 (country,city)
>> >> affinity_key=country join with «city» usage — will be correct here (i
>> hope,
>> >> need to recheck of course) thus seems you must give some flag\hint what
>> >> ever to run such reqs.
>> >>
>> >> thanks !
>> >>
>> >> >Hi, Igniters!
>> >> >
>> >> >Last week I investigated a bug [1]. It's about an incorrect result for
>> >> >non-colocated joins. For such joins it's required to set up the
>> >> >"distributedJoin" flag, or try to make joined tables colocated. It is
>> >> >covered in docs [2]. But it's not obvious and some users don't read
>> that
>> >> or
>> >> >forget about that. In result there are wrong results for some queries
>> that
>> >> >are pretty hard to debug.
>> >> >
>> >> >There is a ticket [3] with a comment, where it's suggested to add a
>> check
>> >> >for such joins. I tried to implement it and found a place where it's
>> >> >possible to put this check. But there is an open question what this
>> check
>> >> >should do. Currently I see 2 ways for that:
>> >> >1. Forbid non-colocated joins that aren't marked with the
>> distributedJoin
>> >> >flag, and throw an exception.
>> >> >2. Check every query for such joins and implicitly setup a
>> distributedJoin
>> >> >flag for them.
>> >> >
>> >> >Both solutions may break compatibility, but is this compatibility OK?
>> >> >
>> >> >Igniters, what do you think?
>> >> >
>> >> >[1]  https://issues.apache.org/jira/browse/IGNITE-12847
>> >> >[2]
>> >> >
>> >>
>>  https://ignite.apache.org/docs/latest/SQL/distributed-joins#distributed-joins
>> >> >[3]  https://issues.apache.org/jira/browse/IGNITE-13019
>> >>
>> >>
>> >>
>> >>
>>
>>
>>
>> 
 
 
 
 
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