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From: Koen De Groote <[email protected]>
To: Adrian Klaver <[email protected]>
Cc: PostgreSQL General <[email protected]>
Subject: Re: Foreign Data Wrapper behavior?
Date: Sat, 12 Oct 2024 20:32:04 +0200
Message-ID: <CAGbX52FkdEqnr=JvRDY0yr0tsk2PGtfaejj3eA18jvYcmfQFnw@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
References: <CAGbX52Eqa25L1afuVq6NWfnMfmwV5m5zpek=whU8=5U-E9unxQ@mail.gmail.com>
	<[email protected]>

Ah, thanks for that

On Fri, Oct 11, 2024 at 5:59 PM Adrian Klaver <[email protected]>
wrote:

> On 10/11/24 04:08, Koen De Groote wrote:
> > In the release notes for postgres 17 I'm reading:
> >
> >  > The PostgreSQL foreign data wrapper (postgres_fdw), used to execute
> > queries on remote PostgreSQL instances, can now push EXISTS and IN
> > subqueries to the remote server for more efficient processing.
> >
> > I'm confused as to what this means. In older versions, are parts of
> > queries not sent to the foreign server? Or is this change meant to imply
> > the sending of only the subqueries, the result of which is then directly
> > used in pushing the entire query?
> >
> > Or am I still wrong as to what this means?
> >
> > I looked at the documentation and there doesn't seem to be any
> > indication of particular queries not being pushed to the foreign server,
> > so this wording that "can now push EXISTS and IN subqueries to the
> > remote server" is confusing.
> >
> > What am I missing?
>
> Read:
>
>
> https://www.postgresql.org/docs/current/postgres-fdw.html#POSTGRES-FDW-REMOTE-QUERY-OPTIMIZATION
>
> F.36.5. Remote Query Optimization
>
>
> As to the change in the Release Note see the --hackers discussion:
>
>
> https://www.postgresql.org/message-id/c9e2a757cf3ac2333714eaf83a9cc184%40postgrespro.ru
>
> >
> > Regards,
> > Koen De Groote
>
> --
> Adrian Klaver
> [email protected]
>
>

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