Re: buffer cache hit ration calculation

Let's imagine I did:

    100 physical
    10000 logical (eg, db block + consistent gets) According to 1), hit ratio would be 2.
According to 2), it would be 99
Since the ratio is supposed to be a percentage, 2) seems more appropriate.

cosmin wrote:

> hello all;
>
> I am preparing for the OCP exam and I have a problem with the buffer cache
> hit ratio calculation:
>
> 1) The OCP DBA Certif Exam Guide by Couchman (ISBN 0-07-882549-0) says on
> page 875,
>
> cache hit ratio = (Physical Reads/(db block gets + consistent gets))
> * 100
>
> 2) The Oracle8 Advanced Tuning and Administration by Aronoff, Loney,
> Sonawalla (ISBN 0-07-882534-2) says on page 45
>
> cache hit ration = ((consistent gets + db block gets - physical
> gets)/(consistent gets + db block gets)) *100
>
> which one is correct?
>
> Thank you,
>
> Cosmin

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