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

  • From: Mladen Gogala <mgogala@xxxxxxxxxxxxxxxxxxxx>
  • To: cmarquez@xxxxxxxxxxxxxxxx
  • Date: Thu, 16 Jun 2005 16:49:36 -0400

Marquez, Chris wrote:

>Mladen,
>Thanks for the very technical explanation although I honestl;y didn't follow 
>it.
>
>  
>
>>>Your oracle waiting times will be 
>>>reflecting this and blur any comparison.
>>>In short, you cannot compare. 
>>>In the old tuning books, when DBA used to
>>>be much more conscientious of the underlying OS,
>>>      
>>>
>
>
>Can't compare;
>"NON-cached" filesystems vs. "cached" filesystems
>or can't compare;
>"db file scattered reads" vs. "db file sequential reads"
>
>Not sure what you mean?
>
>  
>
You cannot compare  db file scattered reads with  db file sequential 
reads because the mechanism for
the two types of read  is very different and you cannot make any 
assumptions about the relationship
between waits on those two events. I wasn't comparing the file system 
types at all.

-- 
Mladen Gogala
Oracle DBA
Ext. 121


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