Re: CPU COSTING
- From: "Jonathan Lewis" <jonathan@xxxxxxxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 23 Apr 2004 17:13:38 +0100
You collect statistics for a "typical" period.
(Session 10 - slide 14 of Optimising Oracle)
Simplest option:
execute dbms_stats.gather_system_stats('start')
twiddle thumbs for a while
execute dbms_stats.gather_system_stats('stop')
You can set sql_trace true to see what actually happens.
The idea is that you want Oracle to optimise the SQL
for a given machine load - and the machine load is
represented by the relative I/O speeds, and the
apparent CPU speed.
Lapsing into economics - the old CBO worked on the
Adam Smith principle .. every does the best they can
and the market makes things stabilise; the new CBO
works on the John Nash equilibrium .. if everyone knows
what everyone else is doing, then there is a point at which
not unilateral change can improve the net benefit.
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: "Khedr, Waleed" <Waleed.Khedr@xxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Friday, April 23, 2004 4:59 PM
Subject: RE: CPU COSTING
I was talking about how it gets populated, or the processes involved in =
calculating the numbers there. if the numbers are already in v$filestat, =
why do I have to collect it?
Regards,
Waleed
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