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Home -> Community -> Mailing Lists -> Oracle-L -> Re: Buffer cache Hit - Perf overview
John,
You went really fast over the biggest fallacy Sundar was operating under:
that even though response time was acceptable he had to continue to tune.
When no one is complaining..... STOP TUNING! There are many many other things to occupy a DBA's time. If it's not broke, don't fix it!
Rachel
>From: John Kanagaraj <JKanagaraj_at_mfi.com>
>Reply-To: ORACLE-L_at_fatcity.com
>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>Subject: Re: Buffer cache Hit - Perf overview
>Date: Thu, 26 Oct 2000 10:20:36 -0800
>
>Hi Sundar,
>
> > I was used to near 99% Hit on 7.3, managed 98% 0n 8.1.5
> > But can't seem to get above 90% Buffer cache hit on 8.1.6. 8i.
> > Has anyone managed to get near or above 95%.
> > Response from my website I have configured (creativebase.com) is good
>from the outside world but as a DBA I am not happy for the DB. Anybody
>using the similar config ? Results ? Comments appreciated.
>
>/SOAPBOX ON, FLAMEPROOF SUIT ON
>
>This is one myth that is being broken (and not too soon!). You (and many
>of us) need to unlearn the notion that a 99% hit ratio is not
>necessarily GOOD. As you yourself stated, the response is good, so
>what's the problem??
>
>/SOAPBOX OFF, FLAMEPROOF SUIT OFF
>
>Have a look at V$SYSTEM_EVENT and look at what the Database has been
>waiting for the most (set TIMED_STATISTICS=TRUE if not yet). From there,
>drill down to V$SESSION_EVENT and V$SESSION_WAIT to see what if any
>sessions are waiting on, and take it from there. There is no point in
>achieving 99% buffer hits if a session is waiting on a particular
>hot-spot object.
>
>A good description of what this 'Wait Interface' (by Mogens Norgaard) is
>all about is described in a paper in Cary Millsap's Hotsos website
>(http://www.hotsos.com). It used to be free, but is now restricted.
>Worth subscribing to/reading.
>
>(Sorry Gaja - stole your thunder!)
>
>John
>--
>Please see the official ORACLE-L FAQ: http://www.orafaq.com
>--
>Author: John Kanagaraj
> INET: JKanagaraj_at_mfi.com
>
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Share information about yourself, create your own public profile at Received on Thu Oct 26 2000 - 14:48:39 CDT
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