Re: Tim Gorman's "...Cost-Based Optimizer.doc"

  • From: Mladen Gogala <mgogala@xxxxxxxxxxxxxxxxxxxx>
  • To: Wolfgang Breitling <breitliw@xxxxxxxxxxxxx>
  • Date: Thu, 16 Jun 2005 14:07:24 -0400

Wolfgang Breitling wrote:

> I believe that if scattered, i.e. multi-block, reads are faster than 
> sequential, i.e. single-block, reads it is because the SAN recognized 
> a read pattern and prefetched the next bunch of block into the cache.

Now, that would only be possible if your SAN apparatus is more 
intelligent then Geraldo Rivera. Not that it's very hard,
but the only type of SAN device that can recognize patterns is EMC 
Symmetrix (the very top of the line) and they are
prohibitively expensive.

Mladen Gogala
Oracle DBA
Ext. 121


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