RE: CPU COSTING
- From: "Khedr, Waleed" <Waleed.Khedr@xxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 23 Apr 2004 09:57:57 -0400
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@xxxxxxxxxxxxxxxxxx]
Sent: Friday, April 23, 2004 4:23 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=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@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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