Re: Oracle slowed down

"ianal Vista" <ianal_vista_at_hotmail.com> wrote in message news:Xns97ADBAD5D37E5ianalvistahotmailcom_at_70.169.32.36...
> "Bob Jones" <email_at_me.not> wrote in
> news:5oz2g.13722$4L1.13455_at_newssvr11.news.prodigy.com:
>
>>
>> "ianal Vista" <ianal_vista_at_hotmail.com> wrote in message
>> news:Xns97ADAA1CDFD1Dianalvistahotmailcom_at_70.169.32.36...
>>> "Bob Jones" <email_at_me.not> wrote in news:IXy2g.13714$4L1.12286
>>> @newssvr11.news.prodigy.com:
>>>
>>>>
>>>> "HansF" <News.Hans_at_telus.net> wrote in message
>>>> news:pan.2006.04.22.22.14.55.540761_at_telus.net...
>>>>> On Sat, 22 Apr 2006 22:56:20 +0000, Bob Jones wrote:
>>>>>
>>>>>> The only thing I disagree with here is that BCHR is deprecated or
>>>>>> irrelevant.
>>>>>
>>>>> Not deprecated does not imply relevant.
>>>>>
>>>>
>>>> No, it does not. BCHR is neither deprecated nor irrelevant.
>>>>
>>>>
>>>
>>> Since the BCHR can be achieved at what ever value that is desired,
>>> how is BCHR relevant & to who?
>>
>> To people who make distinction between application tuning and buffer
>> cache tuning.
>>
>>
>>
>
> http://asktom.oracle.com/pls/ask/f?p=
> 4950:8:11500305522999310977::NO::F4950_P8_DISPLAYID,F4950_P8
> _CRITERIA:4973488577582
>
> http://www.hotsos.com/e-library/abstract.php?id=6
>
> "Abstract: Many tuning professionals and textbook authors sell
> advice encouraging their customers to enjoy the performance virtues of
> Oracle database buffer cache hit ratios that approach 100%. However,
> database buffer cache hit ratio is not a reliable system performance
> metric.
> Buffer cache hit ratios above 99% usually indicate particularly
> serious SQL inefficiencies. Repairs of these inefficiencies often yield
> 100x or greater performance improvements, yet the optimizations result
> in reduced database buffer cache hit ratios. This paper shows why a 99%+
> buffer cache hit ratio almost always signals performance inefficiencies,
> including real-life examples. It shows how to detect the inefficiencies
> and how to repair them. It concludes with recommendations about what
> metrics the performance analyst should use instead of the venerable but
> unreliable database buffer cache hit ratio."
> ^^^^^^^^^^

That is another example showing hit ratio is relevant, not useless. Received on Sat Apr 22 2006 - 21:43:36 CDT