Re: [Again] Postgres performance problem

On Sep 12, 2007, at 2:19 PM, Frank Schoep wrote:

> On Sep 12, 2007, at 9:07 PM, Scott Marlowe wrote:
>> On 9/12/07, Mikko Partio <mpartio(at)gmail(dot)com> wrote:
>>> …
>>> Aren't you mixing up REINDEX and CLUSTER?
>>
>> …
>> Either one does what a vacuum full did / does, but generally does
>> it better.
>
> On topic of REINDEX / VACUUM FULL versus a CLUSTER / VACUUM ANALYZE
> I'd like to ask if CLUSTER is safe to run on a table that is in
> active use.
>
> After updating my maintenance scripts from a VACUUM FULL (add me to
> the list) to CLUSTER (which improves performance a lot) I noticed I
> was getting "could not open relation …" errors in the log while the
> scripts ran so I reverted the change. This was on 8.1.9.

You'd probably see the same behavior on 8.2.x. CLUSTER is not
transactionally safe so you don't want to run CLUSTER on tables that
are actively being used. I believe that's been fixed for 8.3.

Erik Jones

Software Developer | Emma®
erik(at)myemma(dot)com
800.595.4401 or 615.292.5888
615.292.0777 (fax)

Emma helps organizations everywhere communicate & market in style.
Visit us online at http://www.myemma.com