Re: buffer hit cache ratio

From: Niall Litchfield <n-litchfield_at_audit-commission.gov.uk>
Date: Tue, 23 Dec 2003 10:04:23 -0000
Message-ID: <3fe81327$0$9385$ed9e5944@reading.news.pipex.net>

"Noons" <wizofoz2k_at_yahoo.com.au.nospam> wrote in message news:3fe80871$1$18389$afc38c87_at_news.optusnet.com.au...
> "Tom Brown" <tomNOSPAM_at_teameazyriders.com> wrote in message
news:RDJFb.3901$2x.35138735_at_news-text.cableinet.net...
> > What is an acceptable hit ratio?
>
> Ask the mob.
>
>
> > currently i have about 84% and although the performance is fine i'm
curious
> > if i can make it better?
>
> If the performance is fine and you don't have a ridiculously small
> buffer cache for the working set size of your db buffers,
> then leave the darn thing ALONE! It's useless to even try to
> make it meet a given value in those conditions.

I've given my Myths presentation 3 times now and in only 1 case did I *not* find someone whose performance was judged on an acceptable value of BCHR, either in terms of bonus or in terms of an SLA. It may be useless for the system to focus on a target figure but it may not be so useless for the analyst :(

there is a lesson here about setting suitable targets..

-- 
Niall Litchfield
Oracle DBA
Audit Commission UK

Received on Tue Dec 23 2003 - 04:04:23 CST