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

On 2003-12-30, Geomancer <pharfromhome_at_hotmail.com> 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?

Cache hit ratios are dependent on how dispersed your data is. It doesn't matter how small your cache is relative to your physical data as much as what your code is doing.

Locality of reference(s) is the key.

>
> I still find it hard to beleive that a logical I/O is only 10x-100x
> faster than a disk read.

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