From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Greg Stark <stark(at)mit(dot)edu> |
Cc: | Daniel Farina <daniel(at)heroku(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: pg_upgrade and statistics |
Date: | 2012-03-13 19:44:28 |
Message-ID: | 14582.1331667868@sss.pgh.pa.us |
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Lists: | pgsql-hackers |
Greg Stark <stark(at)mit(dot)edu> writes:
> On Tue, Mar 13, 2012 at 1:38 AM, Daniel Farina <daniel(at)heroku(dot)com> wrote:
>> You probably are going to ask: "why not just run ANALYZE and be done
>> with it?"
> Uhm yes. If analyze takes a long time then something is broken. It's
> only reading a sample which should be pretty much a fixed number of
> pages per table. It shouldn't take much longer on your large database
> than on your smaller databases.
The data collection work does scale according to the statistics target,
which is something that's crept up quite a lot since the code was
originally written.
I wonder whether it'd be worth recommending that people do an initial
ANALYZE with a low stats target, just to get some stats in place,
and then go back to analyze at whatever their normal setting is.
regards, tom lane
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