Niall Litchfield wrote:
> DA Morgan wrote:
>
>>Noons wrote:
>>
>>
>>>DA Morgan wrote:
>>>
>>>
>>>
>>>>Well EXPLAIN PLAN certainly doesn't like it:
>>>
>>>
>>>Funny how 10.1 is so different from 9ir2...
>>>I wonder how much we can rely on the explain plan "cost"
>>>to mean anything, after all it's just a convention rather
>>>than an absolute number.
>>>
>>>The stats on the other hand tell us exactly what
>>>is going on re consistent gets vs physical gets.
>>>Or so they should, but that's not 100% certain either!
>>
>>What I've heard is that the biggest difference between the
>>9i CBO and the 10g CBO is that in 10g the optimizer takes
>>into account CPU. That may well be true but doesn't seem
>>to explain the result.
>
>
>
> I suspect that your comment is missing 'by default' at the end of it!
> CPU costing is certainly available in 9.2 You get it when you choose to
> collect system statistics.
> Niall Litchfield
> Oracle DBA
> http://www.niall.litchfield.dial.pipex.com
You are correct. And as I am sure the CBO uses the same mechanisms used
by RAC it also now takes into account bus speed.
--
Daniel A. Morgan
University of Washington
damorgan_at_x.washington.edu
(replace 'x' with 'u' to respond)
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Received on Mon Jan 10 2005 - 17:06:36 CST
