Re: [Again] Postgres performance problem

On Sep 12, 2007, at 9:07 PM, Scott Marlowe wrote:
> On 9/12/07, Mikko Partio <mpartio@gmail.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.

Am I hitting a corner case or is it generally not a good idea to
CLUSTER tables which are being queried? I haven't had problems with
the REINDEX / VACUUM FULL combination while CLUSTER / VACUUM ANALYZE
resulted in errors on the first run.

Can the "could not open relation…" error bring down the whole
database server? I'm really interested in using CLUSTER regularly as
it speeds up my system by a factor of two because of more efficient I/O.

Sincerely,

Frank