| From: | David Fetter <david(at)fetter(dot)org> |
|---|---|
| To: | "A(dot) Kretschmer" <andreas(dot)kretschmer(at)schollglas(dot)com> |
| Cc: | PG Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [GENERAL] question (or feature-request): over ( partition by ... order by LIMIT N) |
| Date: | 2010-03-25 21:17:31 |
| Message-ID: | 20100325211731.GA16362@fetter.org |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general pgsql-hackers |
On Wed, Mar 24, 2010 at 06:31:59PM +0100, A. Kretschmer wrote:
> Hello @all,
>
> I know, i can do:
>
> select * from (select ... row_number() over (...) ...) foo where
> row_number < N
>
> to limit the rows per group, but the inner select has to retrieve
> the whole set of records and in the outer select most of them
> discarded.
That sounds like the optimizer's falling down on the job. Would this
be difficult to fix?
Cheers,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
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