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RE: RE: A Tale of Two Servers...

From: Wolfgang Breitling <>
Date: Thu, 10 Apr 2003 06:38:49 -0800
Message-ID: <>

I didn't dare to say it, but that were my thoughts as well. There is no way that the size of an L1-3 cache, any cache except Oracle's buffer pool, can have an effect on the number of LIOs. Their speed, yes but not their number. The best explanation I can come up with is that the data in the second, faster, server is better clustered, potentially by importing the data from the first server. Rebuilding the indexes on the first server may go some ways toward streamlining the acces, but the data may still be scattered all over the place. Unless the databases are clones of each other - which they obviously are not - you can not make a valid comparison between the two.

At 01:28 AM 4/10/2003 -0800, you wrote:
> I wish I could put it more diplomatically but IMHO the answer you got
> from OWS is pure rubbish. I could agree to a 'hardware on amphetamines'
> explanation if the only difference was to be found in cpu time. But
> saying that CPU cache affects the LIO count (as opposed to speed) is
> utter nonsense; something like 2 or 3% at most of the Oracle kernel code
> is OS-dependent, do you seriously believe they can afford taking subtle
> hardware differences into account? Certainly not. OWS have jumped on the
> only difference they could see to find a reason to close the case.
>There is obviously something else, although I have no credible explanation
>coming to mind. Ian's db_block_size was an excellent idea. If this is the
>same, could there be a difference in the physical structure of indexes? I
>am thinking of something causing the equivalent of the table 'full scan up
>to the HWM' which has occasionally burnt some of us. Have you tried a
>VALIDATE INDEX (does it still exist?) on both databases? Or rebuilding all
>involved indexes on the slower server?

Wolfgang Breitling
Centrex Consulting Corporation

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Author: Wolfgang Breitling

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Received on Thu Apr 10 2003 - 09:38:49 CDT

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