Good examples are SAP and Documentum which "migrated"
from RBO to CBO by dropping the index adjustment from
100 to 10 (thus making virtually any index look
fantastic, ie simulating rule)
Unlike them, I would recommend a little more
dilligence (as Tim's document sets out)
hth
connor
- "Sakthi , Raj" <rajan_sakthi_at_yahoo.com> wrote: >
Vivek,
> As John K Suggested, take a look at Tim's paper
> "The Search for Intelligent Life in the Cost-Based
> Optimizer". He discussed the impact of these
> settings.
>
> http://www.evergreen-database.com/
>
> Gaja also discusses these parameters and their
> possibly optimal values in his paper. You can find
> that in quest's web site.
>
> HTH
> Cheers,
> RS
>
>
> --- VIVEK_SHARMA <VIVEK_SHARMA_at_infosys.com> wrote:
> >
> > What would be an Optimal Reduced Value of
> > OPTIMIZER_INDEX_COST_ADJ
> > to make it favour index searches ?
> >
> > Default Value is 100.
> >
> > Thanks
> >
> >
> > -----Original Message-----
> > Sent: Wednesday, November 20, 2002 4:54 PM
> > To: Multiple recipients of list ORACLE-L
> >
> >
> > One quick hack is to set the "optimizer_..."
> params
> > to
> > make indexes look super-wonderful, which then
> gives
> > you a rule-based "look and feel" with hopefully a
> > little smarter selection of indexes as a bonus
> >
> > hth
> > connor
> >
> > --- VIVEK_SHARMA <VIVEK_SHARMA_at_infosys.com>
> wrote:
> > >
> > > Consider using OUTLINES for Fixed Execution
> plans
> > > especially for Batch Queries
> > >
> > > This will prevent a Sudden Increment in
> Processing
> > > Time due to Optimizer choosing NON-Optimal paths
> > >
> > >
> > > -----Original Message-----
> > > Sent: Wednesday, November 20, 2002 3:20 AM
> > > To: Multiple recipients of list ORACLE-L
> > >
> > >
> > > We will be in the same process soon.
> > > We'll have to consolidate over 100 instances to
> > > something between 40-60 instances and switch
> from
> > > RBO
> > > to CBO.
> > >
> > > Any tips are welcome.
> > >
> > >
> > > --- Steve McClure <smcclure_at_usscript.com> a
> écrit
> > :
> > > >
> > > I am just starting to look at converting to the
> > cost
> > > > based optimizer, and am
> > > > hoping a few of you can share insights from
> > having
> > > > done so in the past. Our
> > > > application is an oltp system developed on
> > 7.3.4.
> > >
> > > > We made liberal use of
> > > > +0 and other RBO "hints", and I am wondering
> if
> > > > these are going to cause us
> > > > troubles when switching to CBO.
> > > >
> > > > We have been on 8i since April of this year,
> > and
> > > I
> > > > am just now starting to
> > > > gather information on the inner workings of
> the
> > > CBO.
> > > > I know it is where I
> > > > want to be, I am just looking to see how
> > > > painful/painless the transition
> > > > will be.
> > > >
> > > > Steve McClure
> > > >
> > > > --
> > > > Please see the official ORACLE-L FAQ:
> > > > http://www.orafaq.com
> > > > --
> > > > Author: Steve McClure
> > > > INET: smcclure_at_usscript.com
> > > >
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> >
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> >
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> === message truncated ===
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>
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Connor McDonald
http://www.oracledba.co.uk
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"GIVE a man a fish and he will eat for a day. But TEACH him how to fish, and...he will sit in a boat and drink beer all day"
Do You Yahoo!?
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Received on Wed Nov 20 2002 - 09:34:04 CST
