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Re: VACUUM on duplicate DB gives FSM and total pages discrepancies

From: Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
To: Karim Nassar <karim(dot)nassar(at)acm(dot)org>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: VACUUM on duplicate DB gives FSM and total pages discrepancies
Date: 2005-03-30 15:19:03
Message-ID: 20050330151903.GD32434@dcc.uchile.cl (view raw or flat)
Thread:
Lists: pgsql-performance
On Tue, Mar 29, 2005 at 05:52:58PM -0700, Karim Nassar wrote:
> I recently pg_dumpall'd my DB from a (used for testing) v20z install of
> postgresql 8.0.1, and restored it to my production (but not yet in
> service) v40z running the same version. The test DB has had multiple
> millions of rows created/dropped during testing. The results of VACUUM
> VERBOSE are giving me pause:

The FSM only stores pages that have some free space.  If the database
has only been through a restore, then probably there aren't many of
those.  After you start playing with the data some more pages will need
registering.  So the behavior you are seeing is expected.

-- 
Alvaro Herrera (<alvherre[(at)]dcc(dot)uchile(dot)cl>)
"We are who we choose to be", sang the goldfinch
when the sun is high (Sandman)

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