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

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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