Re: Autovacuum / full vacuum - Mailing list pgsql-performance

From Michael Riess
Subject Re: Autovacuum / full vacuum
Date
Msg-id dqiv77$2ijp$1@news.hub.org
Whole thread Raw
In response to Re: Autovacuum / full vacuum  ("Matthew T. O'Connor" <matthew@zeut.net>)
Responses Re: Autovacuum / full vacuum  (Tom Lane <tgl@sss.pgh.pa.us>)
Re: Autovacuum / full vacuum  (Markus Schaber <schabi@logix-tt.com>)
List pgsql-performance
Hi,

yes, some heavily used tables contain approx. 90% free space after a
week. I'll try to increase FSM even more, but I think that I will still
have to run a full vacuum every week. Prior to 8.1 I was using 7.4 and
ran a full vacuum every day, so the autovacuum has helped a lot.

But actually I never understood why the database system slows down at
all when there is much unused space in the files. Are the unused pages
cached by the system, or is there another reason for the impact on the
performance?

Mike


 >  Have you measured to see if things are truly
> faster after a VACUUM FULL?
>
> Matt
>
> ---------------------------(end of broadcast)---------------------------
> TIP 6: explain analyze is your friend
>

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