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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
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Lists: pgsql-hackers
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>

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

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