Re: Pulling up direct-correlated ANY_SUBLINK - Mailing list pgsql-hackers

From Richard Guo
Subject Re: Pulling up direct-correlated ANY_SUBLINK
Date
Msg-id CAN_9JTzqa-3RmHAw3wZv099Rk8xX480YdEvGy+JAdVw8dTnHRA@mail.gmail.com
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In response to Re: Pulling up direct-correlated ANY_SUBLINK  (Antonin Houska <ah@cybertec.at>)
Responses Re: Pulling up direct-correlated ANY_SUBLINK
List pgsql-hackers

On Thu, Sep 12, 2019 at 11:35 PM Antonin Houska <ah@cybertec.at> wrote:
Richard Guo <riguo@pivotal.io> wrote:

> On Wed, Sep 11, 2019 at 3:25 PM Antonin Houska <ah@cybertec.at>
> wrote:
>
>   
>     Nevertheless, I don't know how to overcome the problems that I
>     mentioned
>     upthread.
>
>
> Do you mean the problem "the WHERE clause of the subquery didn't
> participate in the SEMI JOIN evaluation"? Good news is it has been
> fixed
> by commit 043f6ff0 as I mentioned upthread.

Do you say that my old patch (rebased) no longer breaks the regression tests?

I think so.
 

(I noticed your other email in the thread which seems to indicate that you're
no lo longer interested to work on the feature, but asking out of curiosity.)

Tom pointed out that even if we pull up the subquery with the help of
LATERAL, we cannot make sure we will end up with a better plan, since
LATERAL pretty much constrains things to use a nestloop. Hmm, I think
what he said makes sense.

Thanks
Richard
 

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