Re: Buffer cache statistics (ratios) and CBO SQL optimization?

"Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> wrote in message news:bsua97$rsb$1$8300dec7_at_news.demon.co.uk...

> Basically it is pointing out that the code
> path to
> calculate hash
> latch
> pin
> drop latch
> ACCESS DATA - time unknown
> latch
> unpin
> drop latch
> is going to be fairly constant, and a significant
> fraction of the total cost of an LI/O provided
> you don't do anything horrible at the ACCESS
> DATA bit.
>

Would this also stand for an index block access? I'm just reminded of Steve's argument in the "7 sins" about the root index block access not being scalable. That would be mostly because of the above?

> Over the years, across different plaforms, and
> different versions of Oracle, I've seen a variation
> in my base test from about 5,000 to 17,000.

Has it changed significantly between 8i and 9i?

-- 
Cheers
Nuno Souto
wizofoz2k_at_yahoo.com.au.nospam