Re: slow vacuum performance

pginfo wrote:
> Hi,
>
> I am running pg 7.4.1 on linux box.
> I have a midle size DB with many updates and after it I try to run
> vacuum full analyze.
> It takes about 2 h.
> If I try to dump and reload the DB it take 20 min.
>
> How can I improve the vacuum full analyze time?

How often are you vacuuming?  If you've gone a LONG time since the last vacuum,
it can take quite a while, to the point where a dump/restore is faster.

A recent realization that I've had some misconceptions about vacuuming led me
to re-read section 8.2 of the admin guide (on vacuuming) ... I highly suggest
a review of these 3 pages of the admin manual, as it contains an excellent
description of why databases need vacuumed, that one can use to determine how
often vacuuming is necessary.

--
Bill Moran
Potential Technologies
http://www.potentialtech.com