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From Mich Talebzadeh <mich.talebza...@gmail.com>
Subject Re: Optimized Hive query
Date Tue, 14 Jun 2016 16:58:09 GMT
Amazing. that is the first time I have heard that an optimizer does not
have the concept of flattened query?

So what is the definition of syntax tree? Are you referring to the industry
notation "access path". This is the first time I have heard of such
notation called syntax tree. Are you stating that there is somehow some
explanation for optimiser "access path" that comes out independent of  the
optimizer and is called syntax tree?



Dr Mich Talebzadeh



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On 14 June 2016 at 17:46, Markovitz, Dudu <dmarkovitz@paypal.com> wrote:

> It’s not the query that is being optimized but the syntax tree that is
> created upon the query (execute “explain extended select …”)
>
> In no point do we have a “flattened query”
>
>
>
> Dudu
>
>
>
> *From:* Aviral Agarwal [mailto:aviral12028@gmail.com]
> *Sent:* Tuesday, June 14, 2016 10:37 AM
> *To:* user@hive.apache.org
> *Subject:* Re: Optimized Hive query
>
>
>
> Hi,
>
> Thanks for the replies.
>
> I already knew that the optimizer already does that.
>
> My usecase is a bit different though.
>
> I want to display the flattened query back to the user.
>
> So I was hoping of using internal Hive CBO to somehow change the AST
> generated for the query somehow.
>
>
>
> Thanks,
>
> Aviral
>
>
>
> On Tue, Jun 14, 2016 at 12:42 PM, Gopal Vijayaraghavan <gopalv@apache.org>
> wrote:
>
>
> > You can see that you get identical execution plans for the nested query
> >and the flatten one.
>
> Wasn't that always though. Back when I started with Hive, before Stinger,
> it didn't have the identity project remover.
>
> To know if your version has this fix, try looking at
>
> hive> set hive.optimize.remove.identity.project;
>
>
> Cheers,
> Gopal
>
>
>
>
>

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