Re: optimizer settings
- From: "Jonathan Lewis" <jonathan@xxxxxxxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 2 Mar 2004 08:10:56 -0000
That was the interpretation that Tim Gorman
supplied as a nice 'human' way of looking at
it. Since it still works in 9i, you could (for
values up to 100) view it as the fraction of
single block visits that are likely to turn into
disk read requests. Then the sreadtim is a
number that tells you how long each of the
reads takes.
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
March 2004 Hotsos Symposium - The Burden of Proof
Dynamic Sampling - an investigation
March 2004 Charlotte OUG (www.cltoug.org) CBO Tutorial
April 2004 Iceland
June 2004 UK - Optimising Oracle Seminar
----- Original Message -----
From: "Lim, Binley" <Binley.Lim@xxxxxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Monday, March 01, 2004 11:12 PM
Subject: RE: optimizer settings
>
> I thought CPU costing is supposed to do that for you, without having to
> tweak O_I_C_A yourself...?
>
> > -----Original Message-----
> > From: K Gopalakrishnan [SMTP:kaygopal@xxxxxxxxx]
> > Sent: Tuesday, March 02, 2004 3:58 AM
> > To: oracle-l@xxxxxxxxxxxxx
> > Subject: Re: optimizer settings
> >
> > Jaffar:
> >
> > They are the default settings on 9i. You may not need to tweak the max
> > permutations
> > unless you have more than 7-8 tables in where condition. However you can
> > reduce the
> > optimizer_index_cost _adj after some analysis on single block read to
> > multiblock read
> > timings. You can find 'Search for Intelligence in CBO' paper by Tim
Gorman
> > in his
> > site www.evdbt.com
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