Re: pg_upgrade and statistics

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
Cc: Daniel Farina <daniel(at)heroku(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: pg_upgrade and statistics
Date: 2012-03-13 15:16:16
Message-ID: 20120313151616.GM10441@momjian.us
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On Tue, Mar 13, 2012 at 12:08:41PM -0300, Alvaro Herrera wrote:
> > > You're wrong. Autovacuum does not consider time, only dead/live tuple
> > > counts. The formulas it uses are in the autovacuum docs; some details
> > > (such as the fact that it skips tables that do not have stat entries)
> > > might be missing.
> >
> > Oh, yes. Thank you for the correction; not sure what I was thinking.
> >
> > How would they trigger an autovacuum then?
>
> We don't have any mechanism to trigger it currently. Maybe we could
> inject fake messages to the stats collector so that it'd believe the
> tables have lots of new tuples and an analyze is necessary.

Ewe! Yes, I thought some more and realized these are system _views_,
meaning we can't just update them with UPDATE. It sounds like something
pg_upgrade will have to do with a server-side function, someday.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ It's impossible for everything to be true. +

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