Re: Cache Hit Ratio from system views

"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"?

> Do yourself a favour and read this
> www.hotsos.com/e-library/abstract.php?id=6 ?
>

Do yourself a favor and read my comments correctly. Received on Sun Aug 26 2007 - 18:13:36 CDT