Re: An Index Scanning Solution question

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От Stephan Szabo
Тема Re: An Index Scanning Solution question
Дата
Msg-id 20040520140932.J22962@megazone.bigpanda.com
обсуждение исходный текст
Ответ на Re: An Index Scanning Solution question  (Bruno Wolff III <bruno@wolff.to>)
Список pgsql-hackers
On Thu, 20 May 2004, Bruno Wolff III wrote:

> On Wed, May 19, 2004 at 15:17:01 +0200,
>   Atesz <atesz@ritek.hu> wrote:
> >
> > I'd like to ask why the index scaning can't move on an index in
> > multi-order directions (For exapmle: 1.column: forward, 2.column:
> > backward and 3.column: forward again)? So I wouldn't have to use so many
> > indexes. Has somebody tried to implement this idea in Postgres or is
> > there a more difficult reason in the postgres implementation which
> > cause this defect?
>
> Because there is only one order on an index. So you can only go forward
> and backwards over all of the columns/functions.

If you're willing to make multiple visits you might be able to scan past
and back but I don't know how that'd work for our indexes.


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