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Re: questions on volcano planner


Hi:
1. The Cartesian join maybe discarded by the planner since its cost is much
higher than other?

On Tue, Sep 18, 2018 at 1:49 PM 吴晓菊 <chrysanxia@xxxxxxxxx> wrote:

> Hi Julian,
>
> I'm a developer from eBay(the same org with Kylin), we are now looking into
> your implementation of Volcano planner and trying to implement a new
> optimizer in Spark. We meet some questions when looking into your code, so
> I wrote this email and hope you can help us understand your design:
>
> 1. When applying Commute and Associate rules to get alternative reorder
> plans, we need to handle join conditions, for example,
>       ((A join B on a=b) join C on b=c),
>    it can be transformed to
>       ((A join C on a=c) join B on b=c)
>    if we didn't split the 2 sides of EqualTo, it could be:
>       ((A join C) join B on a=b and b=c)    then A join C becomes a
> Cartesian Join
>    By looking into your code, seems you didn't split the 2 sides of
> EqualTo, how did you avoid the Cartesian Join?
>
> 2. I try to debug into the JoinAssociateRule but failed even though I run
> all your test cases. That's my second question.
>
> Thanks a lot for your time in advance!
>
> Xiaoju Wu
> Phone:+86 17717640807 <177%201764%200807>
>
-- 
Liu, Renjie
Software Engineer, MVAD