Re: Optimizer

I don't agree with this approach. It is quite simple to analyze your tables every week by means by dbms_job.
The rule based optimizer will be taken out soon, with the next major release, and I promise you, you are going to have fun, when all your queries have awful performance.
It's better to prepare now, than to sit back and wait for major disaster occurring.
Also, the cost based optimizer is much less dependent on the 'correct' sequence of tables and other expressions. Sticking to the rule-based optimizer is definitely undesirable.

Regards,

Sybrand Bakker, Oracle DBA

Allan Plesniarski <aplesnia_at_my-deja.com> schreef in berichtnieuws 8fpk5p$uh8$1_at_nnrp1.deja.com...
> When you want to guarantee the same execution plan for a query in all
> cases, the rule hint is still required. If the cost based optimizer is
> not generating efficient plans for all volumes of data, the sql may be
> re-written to best use the rule based approach.
>
> In article <958415535.8780.0.pluto.d4ee154e_at_news.demon.nl>,
> "Sybrand Bakker" <postbus_at_sybrandb.demon.nl> wrote:
> > Rule based optimization is obsolete since 7.1. It is not enhanced
 anymore,
> > so no parallel query, no bitmap indexes, no hints, no nothing.
> > That alone is a reason to forget about it.
> > And yes you can run into wrong query plans because of 'aged'
 statistics.
> >
> > Hth,
> >
> > Sybrand Bakker, Oracle DBA
> >
> > Jeff Hunter <marist89_at_excite.com> schreef in berichtnieuws
> > 391f5eec_at_defiant.btitelecom.net...
> > > I thought I read somewhere that Rule-based optimization will be
 going away
> > > in future versions... When using cost based optimization, your
 objects
 need
> > > to be optimized on a regular basis.
> > >
> > > RL <mark_at_mark-it.demon.co.uk> wrote in message
> > > news:958301705.11737.0.nnrp-14.9e9864e7_at_news.demon.co.uk...
> > > > I appreciate this is probably a huge topic, but can anyone point
> > > > me in the direction of information about the Oracle optimizer.
> > > > In particular, what should the optimizer rule be
> > > > set to (CHOOSE, RULE etc). If the optimizer is using cost
> > > > based optimization, is it necessary to analyze tables regularly or
> > > > can it be run once. Does the cost based optimizer always give
 better
> > > > results that the rule based optimizer or are there too many
 variables
> > > > to decide this.
> > > >
> > > > Are there are good tools to help with optimization, (where to add
> > > > indexes etc), I found tkprof output very cryptic.
> > > >
> > > > Many thanks
> > > >
> > > >
> > > >
> > >
> > >
> >
> >
>
>
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> Before you buy.
Received on Mon May 15 2000 - 00:00:00 CDT