"Richard Foote" <richard.foote_at_nospam.bigpond.com> wrote in message
news:seAAi.26732$4A1.22707_at_news-server.bigpond.net.au...
> "Bob Jones" <email_at_me.not> wrote in message
> news:mOnAi.236$ZA5.16_at_nlpi068.nbdc.sbc.com...
>>
>> "Richard Foote" <richard.foote_at_nospam.bigpond.com> wrote in message
>> news:2_Wyi.24466$4A1.1328_at_news-server.bigpond.net.au...
>>>
>>> "Bob Jones" <email_at_me.not> wrote in message
>>> news:kOtyi.50198$YL5.8637_at_newssvr29.news.prodigy.net...
>>>>
>>>> High BCHR is always better than low - provided everything else being
>>>> equal. If BCHR is useless for the stated reasons, no other indicator
>>>> would be useful.
>>>
>>> This I'm afraid is where you're fundamentally incorrect.
>>>
>>> A high BCHR can mean your database is on life support, struggling to
>>> cope with exessive LIOs due to inefficient SQL with users staring at an
>>> hourglass rather than returned data.
>>>
>>> A BCHR that has increased can mean your database has suddenly hit
>>> significant performance issues. Or it can mean things have improved. Or
>>> it can mean response times remain unaffected.
>>>
>>> A BCHR that has reduced can mean your database has suddenly hit
>>> significant performance issues. Or it can mean things have improved
>>> (yes, improved because that crippling transaction that was previously
>>> performing poorly due to massively exessive LIOs has been fixed,
>>> reducing the overall BCHR) . Or it can mean response times remain
>>> unaffected.
>>>
>>> Not much of an indicator is it ?
>>>
>>> But saying that a BCHR is *always* better than a low is just plain wrong
>>> wrong wrong ...
>>>
>>
>> Didn't I repeatedly say "provided everything else being equal"?
>>
>
> And how precisely do you determine that everything else indeed is equal ?
> Most databases don't exactly remain equal ...
>
No, they do not. That's why you do not look at BCHR alone, as I have said
before.
> And when precisely do you check if everything else is equal with this
> "very meaningful indicator" of yours ? When the BCHR increases ? When the
> BCHR decreases ? When the BCHR remains the same ?
>
Try asking yourself the same questions about any other indicators you
consider meaningful. The question here is not how to determine if everything
else is equal. It is about whether BCHR means anything if everything else is
equal.
Received on Tue Aug 28 2007 - 13:56:03 CDT
