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

Connor McDonald <connor_mcdonald_at_yahoo.com> wrote in message news:<3FF15551.5420_at_yahoo.com>...
> Geomancer wrote:
> >
> > > well they do until you saturate it (30 mins after boot :( ).
> >
> > If I have a 4-gig cacje on top of a 100 gig EMC array, then I only get
> > 4% caching, right?
> >
> > I still find it hard to beleive that a logical I/O is only 10x-100x
> > faster than a disk read.
>
> Its easy enough to test...the hit ratio generator on my site is easily
> modified to do a timing test. The key thing is that an Oracle logical
> I/O is a lot more complex than a "read from memory".
>
> JL has conjectured that you can get approx 10,000 LIO's per sec per
> 100Mhz of CPU.
>
> hth
> connor

im not a hardware guy, but i thought Megaherz didnt matter all that much when you have a sun system? Sun servers have much lower clock speeds than Intel's but are generally considered higher end?

bit off topic, but im curious here. Received on Wed Dec 31 2003 - 07:08:19 CST