Re: Rule Based Optimization Going Away?

Hi,

Apropos of the RBO/CBO switch, what is the 'approved' method of dealing with queries which involve bind variables when using the CBO? As I understand it the table stats are of no use here, since the bind values are unknown at the time the query plan is formulated by the CBO, so it just assumes (usually wrongly) some value distribution in the column. I know this caused me endless headaches when trying to use the CBO previously, since my application uses bind variables exclusively. I eventually gave up, and structured the queries manually to generate a sensible execution plan under RBO. Adrian Bowen

"Daniel Morgan" <dmorgan_at_exesolutions.com> wrote in message news:3D9C678D.33F78118_at_exesolutions.com...
> Peter Kellner wrote:
>
> > I just was told by an Oracle Consultant that Oracle is planning on
> > obsoleting rule based optimization and that in the future sometime,
> > everyone will have to use cost based. Could this be true? I have
> > always used rule based when I know the distribution of the data pretty
> > well ahead of time and can be smarter than the cost optimizer.
> >
> > Any official Oracle Info on this would be appreciated.
> >
> > -Peter Kellner
>
> Yes ... and it is about time. The RBO has become about as useful as a
> buggy whip compared to a decently managed database using CBO.
>
> And I strongly disagree that you are smarter than the CBO. You, for
> example, can not decide when NOT to use an index.
>
> Time to learn about DBMS_STATS.
>
> Daniel Morgan
>
Received on Fri Oct 04 2002 - 01:40:27 CDT