Re: Oracle slowed down

From: HansF <News.Hans_at_telus.net>
Date: Sun, 23 Apr 2006 21:10:23 GMT
Message-Id: <pan.2006.04.23.20.15.15.884275@telus.net>

On Sun, 23 Apr 2006 19:15:36 +0200, Frank van Bortel wrote:

> Bob Jones wrote:

>>>> So you have seen 2 completely identical systems, apart from the buffer
>>>> cache, the one with 30% hits outperforms the other with 100% hits. You
>>>> must
>>>> have disks that are faster than memory.
>>>>
>>>>
>>> You're wrong, again.
>>> BCHR does not say a thing about performance.
>>>
>>>
>> If you have seen such systems, I don't doubt you come up with this
>> conclusion.

>
> OK - let's turn this around. I give in. I have a system with a BCHR of
> 85%. Consistently.
>
> Now you tell me - is the performance OK?

Re-reading - in his posts Bob separates 'buffer tuning' from 'application tuning'.

Apparently there is a need to tune the buffer cache for reasons other than making the application[s] work in an optimal fashion. As such, the BCHR might be useful.

I think the bigger question to Bob is ... HOW does he use the BCHR to do tuning? What are the steps? ... the triggers?

Most specifically, how does the use of BCHR relate to performance? Or how would it be used when there is a performance issue?

-- 
Hans Forbrich                           
Canada-wide Oracle training and consulting
mailto: Fuzzy.GreyBeard_at_gmail.com   
*** Top posting [replies] guarantees I won't respond. ***

Received on Sun Apr 23 2006 - 16:10:23 CDT