Re: Understanding Gets, Pins and Reloads - V$librarycache, consideration of evil

Thanks Mark :) I hear your side clear.

After being condemned so bad, when I saw that the **10.2** manual was talking about ratios, I thought maybe it was some kind of exception. I know the subject has been beaten to death, but still seeing it in 10.2 manual was what made me ask the question.

On 5/16/07, Mark W. Farnham <mwf_at_rsiz.com> wrote:
>
> That depends on your moral matrix. For me, I consider the useless
> generation of entropy to be evil. Since brain cells firing use energy,
> thinking about hit ratios generates entropy. Since hit ratios don't amuse me
> as a puzzle or serve any other intellectually pleasing function and since
> they serve no practical purpose, I suppose for me consideration of hit
> ratios is indeed evil.
>
>
>
> If hit ratios were at least as indicative that something needs attention
> as an oil pressure light (rather than a gauge) you might look at them. But
> since assembling the required other information to tell whether the hit
> ratios mean anything provides more information than the hit ratios
> themselves and since the hit ratios themselves add no value to the required
> contextual data to interpret them I find them entirely useless.
>
>
>
> Now the debate about whether the "first inquiry" should be counted as a
> hit, a miss, or nothing in formulating the hit ratio equation is mildly
> entertaining, but since it devolves to the semantic definition of a useless
> metric that leaves me flat as well.
>
>
>
> So, yes, at least small "e" evil.
>
>
>
> The direct questions are:
>
>
>
> 1) Am I waiting for something that should be in cache at steady
> state operation that I threw out for lack of allocating memory or slots?
>
> 2) Is the wait part of a delay of a process I need to have faster to
> meet a service level?
>
> 3) Is removing the part of the delay caused by the lack of
> allocation worth the cost to allocate more (whether or not this brings me
> totally in compliance with the service level) considering relative costs to
> reduce other parts of the delay?
>
> 4) Is it cheaper to over-allocate than it is to get the rest of the
> performance team to stop worrying about it through logic? (Especially if
> your machine is memory rich, this is often sadly true).
>
>
>
>
>
> Regards,
>
>
>
> mwf
>
>
> ------------------------------
>
> *From:* oracle-l-bounce_at_freelists.org [mailto:
> oracle-l-bounce_at_freelists.org] *On Behalf Of *Ram Raman
> *Sent:* Wednesday, May 16, 2007 10:16 AM
> *To:* oracle-l_at_freelists.org
> *Subject:* Re: Understanding Gets, Pins and Reloads - V$librarycache
>
>
>
> <snip>
>
>
>
> I take it using cache hit ratios are not all that evil?
> <snip>
>
>
>
>

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