RE: CPU COSTING

  • From: Wolfson Larry - lwolfs <lawrence.wolfson@xxxxxxxxxx>
  • To: "'oracle-l@xxxxxxxxxxxxx'" <oracle-l@xxxxxxxxxxxxx>
  • Date: Fri, 23 Apr 2004 10:19:11 -0500

Jonathan,
                I thought your article was very positive.  
"It's a great improvement on the Oracle 7/8 version," 
and
"Overall - it's definitely a good thing."

        I'm just wondering why is Connor suggesting that these only be
collected for a few hours?
In 10 it sounds like we won't have that choice.

"We run a job once per month to gather system stats for a couple of hours.
It checks to make sure that sessions/processes are within 75% of their high
water mark before commencing to (hopefully) ensure that the stats are
representative.

Cheers
Connor"

        Thanks
        Larry Wolfson

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of Jonathan Lewis
Sent: Friday, April 23, 2004 3:23 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: Re: CPU COSTING



Re-reading my post, it's not obvious that I approve
of CPU costing and think it should be enabled as 
part of the migration plan from 8 to 9; so I'll just
say it clearly:

    "I approve of CPU costing and think it should be 
    enabled as part of the migration plan from 8 to 9"

The fact that it will cause some surprises and confusion
occasionally is unfortunate.  

One guideline when you've got some system statistics
gathered.  If you've adjusted optimizer_index_cost_adj,
set it back to default, otherwise you've effectively told Oracle
twice that single block reads are cheaper than multiblock reads.
(This was the point of the throwaway comment I made about
Oracle 9 in my DBAZine article on OICA).


Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html

April 2004 Iceland  http://www.index.is/oracleday.php 
June  2004      UK - Optimising Oracle Seminar
July 2004 USA West Coast, Optimising Oracle Seminar
August 2004 Charlotte NC, Optimising Oracle Seminar
September 2004 USA East Coast, Optimising Oracle Seminar
September2004 UK - Optimising Oracle Seminar

----- Original Message ----- 
From: "Wolfson Larry - lwolfs" <lawrence.wolfson@xxxxxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Friday, April 23, 2004 12:38 AM
Subject: RE: CPU COSTING


Jonathan, thanks for heads up.

Tanel, by freaked out, I assume you mean performing at warp speed.

Thanks
Larry Wolfson.


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