| From: | Matthew Wakeling <matthew(at)flymine(dot)org> |
|---|---|
| To: | Ow Mun Heng <ow(dot)mun(dot)heng(at)wdc(dot)com> |
| Cc: | Thomas Finneid <tfinneid(at)fcon(dot)no>, Greg Smith <gsmith(at)gregsmith(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: increase index performance |
| Date: | 2009-05-14 10:20:33 |
| Message-ID: | alpine.DEB.2.00.0905141118360.2341@aragorn.flymine.org |
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| Lists: | 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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