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Re: pg_upgrade and statistics

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Peter Eisentraut <peter_e(at)gmx(dot)net>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Greg Stark <stark(at)mit(dot)edu>,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 20:17:27
Message-ID: 20120313201727.GF23967@momjian.us (view raw or flat)
Thread:
Lists: pgsql-hackers
On Tue, Mar 13, 2012 at 10:10:02PM +0200, Peter Eisentraut wrote:
> On tis, 2012-03-13 at 15:44 -0400, Tom Lane wrote:
> > 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.
> 
> Perhaps going even further, ANALYZE could have a quick-and-dirty mode,
> where it just analyzes say 10 random pages per table and fills in as
> much data as it can from that.  And then it does the real analyze.  (Or
> it could even insert fake statistics to trigger autoanalyze.)  That way,
> you could have a database back in business in less than a minute.

OK, good idea.  Kevin, can you test this:

  PGOPTIONS='-c default_statistics_target=10' vacuumdb --all --analyze-only

Is it faster?  Thanks.

-- 
  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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