Re: testing memory parameters

From: Serge Rielau <>
Date: Sun, 16 Mar 2008 21:44:56 -0400
Message-ID: <>

DA Morgan wrote:
> Ana C. Dent wrote:

>> "" <> wrote in news:62772aa8-fdbd-42b7-
>>> I think that I should consider buffer and library cache hit ratios.
>>> Is this a good way?
>> BUFFER CACHE HIT RATIO ia a mythical indicator of performance.
>> It should be ignored because it is meaningless.

> Just to reinforce what Ana wrote ... hit ratios are meaningless
> nonsense promoted by people who still think they can apply Oracle
> 7 bad practices to current versions of Oracle.
> If you have one of those books that recommends such nonsense do
> something useful with it. I suggest a recycling bin.
Hmmm.. OK I bite. The only thing worse than admitting ignorance being remaining ignorant....

While I agree that a high buffer pool hit ratio is not a guaranty for a well tuned system, in OLTP the lack thereof tends to be a guaranty for a badly tuned system (oftentimes caused by a lack of a good access path such as indexing).
Thus a good hit ratio is generally a necessary, but not sufficient indicator for a well tunes application.
I thought this was a universal rule for the major DBMS.

Is my reasoning wrong as far as Oracle is concerned? If so where?


Serge Rielau
DB2 Solutions Development
IBM Toronto Lab
Received on Sun Mar 16 2008 - 20:44:56 CDT

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