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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 14:49:26
Message-ID: 20120313144926.GK10441@momjian.us (view raw or flat)
Thread:
Lists: pgsql-hackers
On Tue, Mar 13, 2012 at 11:34:16AM -0300, Alvaro Herrera wrote:
> 
> Excerpts from Bruce Momjian's message of mar mar 13 11:14:43 -0300 2012:
> > On Tue, Mar 13, 2012 at 12:33:09AM -0700, Daniel Farina wrote:
> > > On Mon, Mar 12, 2012 at 8:10 PM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> > > > To answer your specific question, I think clearing the last analyzed
> > > > fields should cause autovacuum to run on analyze those tables.  What I
> > > > don't know is whether not clearing the last vacuum datetime will cause
> > > > the table not to be analyzed.
> > > 
> > > Thank you very much for this reference.  I will look into it.
> > 
> > I assume a missing last_analyze would trigger an auto-analyze,
> 
> 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?

-- 
  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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