Re: benchmarking the query planner

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: "Robert Haas" <robertmhaas(at)gmail(dot)com>
Cc: "Josh Berkus" <josh(at)agliodbs(dot)com>, "jd(at)commandprompt(dot)com" <jd(at)commandprompt(dot)com>, "Gregory Stark" <stark(at)enterprisedb(dot)com>, "Nathan Boley" <npboley(at)gmail(dot)com>, "Vladimir Sitnikov" <sitnikov(dot)vladimir(at)gmail(dot)com>, "Greg Smith" <gsmith(at)gregsmith(dot)com>, <pgsql-hackers(at)postgresql(dot)org>,"Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Subject: Re: benchmarking the query planner
Date: 2008-12-12 17:27:59
Message-ID: 49424ABE.EE98.0025.0@wicourts.gov
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>>> "Robert Haas" <robertmhaas(at)gmail(dot)com> wrote:
>> Which raises the issue, if we could get better statistics by
passing
>> the whole table, why not do that when VACUUM ANALYZE is run?
>
> I think the reason is "because the next autovacuum would undo it".

The table has 32.4 million rows.
autovacuum_analyze_scale_factor is 0.1.
autovacuum_vacuum_scale_factor is 0.2.
We run a nightly VACUUM ANALYZE.
Deletes are rare.
Normal operations don't update more than a few thousand rows per day.

I know that normal operations never cause an autovacuum of this table.
Perhaps if there was a way to share this information with
PostgreSQL....

-Kevin

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