Re: increase index performance

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От Matthew Wakeling
Тема Re: increase index performance
Дата
Msg-id alpine.DEB.2.00.0905141118360.2341@aragorn.flymine.org
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Ответ на Re: increase index performance  ("Ow Mun Heng" <ow.mun.heng@wdc.com>)
Ответы Re: increase index performance  ("Ow Mun Heng" <ow.mun.heng@wdc.com>)
Список pgsql-performance
On Thu, 14 May 2009, Ow Mun Heng wrote:
> Shouldn't BITMAP indexes come into play?
>
> Does having one index w/ 3 parameters being better than 3 index w/ 3
> different parameters be better for BITMAP index seeks?

I'll let someone correct me if I'm wrong, but using a single index that
exactly covers your search is always going to be better than munging
together results from several indexes, even if the planner decides to turn
it into a bitmap index scan (which will be more likely in PG8.4 with
effective_concurrency set).

Matthew

--
 I don't want the truth. I want something I can tell parliament!
                                              -- Rt. Hon. Jim Hacker MP

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