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From Zhenya Stanilovsky <arzamas...@mail.ru.INVALID>
Subject Re[2]: [DISCUSSION] Fail on non-colocated join
Date Wed, 03 Feb 2021 11:48:24 GMT



  
>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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