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From mingda li <limingda1...@gmail.com>
Subject Re: About the Multiple Join Optimization on AsterixDB
Date Mon, 31 Oct 2016 18:30:55 GMT
Hi Yingyi,

I see. Thanks for your reply:-)

Bests,
Mingda


On Mon, Oct 31, 2016 at 11:23 AM, Yingyi Bu <buyingyi@gmail.com> wrote:

> Mingda,
>
>      I'm not sure how much re-ordering can be done at the Hyracks level,
> i.e., the runtime level.
>      In the optimizer (the asterixdb/algebricks level), we don't have
> re-ordering for  joins, because:
>      --- the cost model has not been added yet.  I'm not sure about the
> timeline for this. @Ildar?
>      --- respecting user-specified join orders is important for certain
> cases, for example, to get stable/predictable performance (zero surprise)
> for applications.
>
>      In the runtime, we have a role-reversal optimization in hybrid hash
> join, which is a safe optimization that is not based on estimations.  You
> can look at OptimizedHybridHashJoin.
>
> Best,
> Yingyi
>
>
> On Mon, Oct 31, 2016 at 11:16 AM, mingda li <limingda1993@gmail.com>
> wrote:
>
> > Dear all,
> >
> > Hi, I am working on multiple join on Hyracks level. I am not sure if I do
> > the multiple join on AsterixDB, whether it will optimize the query by
> > changing the join order or just execute according to how we write the
> > query. I think this may not be done in Algebricks level based on rule but
> > not sure.
> >
> > Bests,
> > Mingda
> >
>

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