Re: DB Tuning Notes for comment...

From: Philip Warner <pjw(at)rhyme(dot)com(dot)au>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Robert Treat <rtreat(at)webmd(dot)net>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: DB Tuning Notes for comment...
Date: 2002-12-10 01:47:03
Message-ID: 5.1.0.14.0.20021210124459.04bb8fd8@mail.rhyme.com.au
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At 08:39 PM 9/12/2002 -0500, Tom Lane wrote:
>A VACUUM
>done just after startup does not have any historical info to base this
>decision on.

The actual order is:

start
delete
vacuum;
insert <- does not use free space
vacuum;
insert <- does not use free space
vacuum;
vacuum;
insert <- uses free space

my guess is the fact that the second vacuum has no useful statistics means
that (somehow) it is choosing the tables with free space -- perhaps because
they are the largest?

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