Re: Plan time Improvement - 64bit bitmapset

From: Gregory Stark <stark(at)enterprisedb(dot)com>
To: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
Cc: "Andres Freund" <andres(at)anarazel(dot)de>, <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Plan time Improvement - 64bit bitmapset
Date: 2009-06-03 18:57:53
Message-ID: 87ljo987ri.fsf@oxford.xeocode.com
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"Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> writes:

> Andres Freund <andres(at)anarazel(dot)de> wrote:
>
>> long plan times (minutes and up)
>
> Wow. I thought I had some pretty complex queries, including some
> which join using several views, each of which has several joins; but
> I've never gone to multiple seconds on plan time (much less multiple
> minutes!) without very high statistics targets and many indexes on the
> tables. Any rough estimates on those?

My money's still on very large statistics targets. If you have a lot of
columns and 1,000-element arrays for each column that can get big pretty
quickly.

But that doesn't explain the bitmap ops being important. Hm. Actually having a
lot of columns and then joining a lot of tables could mean having fairly large
bitmapsets.

--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com
Ask me about EnterpriseDB's 24x7 Postgres support!

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