RE: CPU COSTING

From: Wolfson Larry - lwolfs <lawrence.wolfson_at_acxiom.com>
Date: Fri, 23 Apr 2004 10:19:11 -0500
Message-ID: <A366E86AF2FBD611AB920002B31E58B0096DC7B6@conmsx07.corp.acxiom.net>

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_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Jonathan Lewis Sent: Friday, April 23, 2004 3:23 AM
To: oracle-l_at_freelists.org
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_at_acxiom.com> To: <oracle-l_at_freelists.org> 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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Received on Fri Apr 23 2004 - 10:20:25 CDT