RE: CPU COSTING

From: Khedr, Waleed <Waleed.Khedr_at_FMR.COM>
Date: Fri, 23 Apr 2004 09:57:57 -0400
Message-ID: <42BBD772AC30EA428B057864E203C9991158E5@MSGBOSCLF2WIN.DMN1.FMR.COM>

Do you know what it (cpu costing) measures : the logical reads or the = physical reads (does the buffer cache affects the numbers)?

Thanks

Waleed

-----Original Message-----

From: Jonathan Lewis [mailto:jonathan_at_jlcomp.demon.co.uk] Sent: Friday, April 23, 2004 4:23 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=20 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=20 enabled as part of the migration plan from 8 to 9"

The fact that it will cause some surprises and confusion occasionally is unfortunate. =20

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=20 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 -----=20 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 - 08:55:03 CDT