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From: Devrim GÜNDÜZ <[email protected]>
To: Tom Lane <[email protected]>
Cc: Peter Eisentraut <[email protected]>
Cc: pgsql-docs <[email protected]>
Subject: Re: Doc patch for truncate.sgml
Date: Thu, 28 Aug 2008 21:48:18 +0300
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
	<[email protected]>
	<[email protected]>

Hi,

On Thu, 2008-08-28 at 14:20 -0400, Tom Lane wrote:
> > If the table is in fact empty, why is it a bad idea to let the 
> > statistics reflect that?
> 
> I think that this thinking is at least partially obsolete now that
> autovacuum/autoanalyze and plan invalidation are in place.  It used to
> be that if you truncated a table and then filled it again, any cached
> plans that were made while the table was really small would tend to
> suck when used with the re-filled table.  But now, autovac will launch
> (at least) an ANALYZE against any table that's grown materially, and
> the commit of the new analyze stats will result in invalidating any
> cached plans.  So the system should be capable of auto-tuning its
> plans to changes in table size ... not instantaneously of course, but
> then you can't fill a big table instantaneously either.

Good point.

-- 
Devrim GÜNDÜZ, RHCE
devrim~gunduz.org, devrim~PostgreSQL.org, devrim.gunduz~linux.org.tr
                   http://www.gunduz.org


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