| From: | "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> |
|---|---|
| To: | "Bruce Momjian" <bruce(at)momjian(dot)us> |
| Cc: | "Peter Eisentraut" <peter_e(at)gmx(dot)net>, "Daniel Farina" <daniel(at)heroku(dot)com>,"Greg Stark" <stark(at)mit(dot)edu>, "pgsql-hackers" <pgsql-hackers(at)postgresql(dot)org>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Subject: | Re: pg_upgrade and statistics |
| Date: | 2012-03-13 22:33:29 |
| Message-ID: | 4F5F84E90200002500046273@gw.wicourts.gov |
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| Lists: | pgsql-hackers |
Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> What is the target=10 duration? I think 10 is as low as we can
> acceptably recommend. Should we recommend they run vacuumdb
> twice, once with default_statistics_target = 4, and another with
> the default?
Here are the results at various settings.
1 : 172198.892 ms
2 : 295536.814 ms
4 : 474319.826 ms
10 : 750458.312 ms
100 : 3433794.609 ms
I'm not sure what's best for a general approach to the problem. For
my own part, I'd be inclined to cherry-pick tables if I were in a
hurry.
I hope we at least bring over relpages and reltuples, to give the
optimizer *some* clue what it's looking at. I wouldn't thing those
would be changing semantics or format very often.
-Kevin
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