Answer to 3) is definite yes - in 10i (speculative name) RBO will be no more.
As for 1) - that depends. But if RBO gives you a better performing plan,
capture the plan and create a stored outline from it and enable stored outlines -
then CBO will work just the same way. 2) - no idea.
--
Vladimir Zakharychev (bob@dpsp-yes.com) http://www.dpsp-yes.com
Dynamic PSP(tm) - the first true RAD toolkit for Oracle-based internet applications.
All opinions are mine and do not necessarily go in line with those of my employer.
"Jonathan Bliss" <bliss_jonathan_at_nossspam.hotmail.com> wrote in message
news:vcS19.2148$sH3.63606_at_newsfep1-win.server.ntli.net...
> Hi
>
> I am working with an application originally written in Oracle 6. A major
> set of reference tables are built as a cluster. These reference tables are
> highly normalized and self referencing. i.e. an item in the main table can
> be related to other items in the same table that can be in turn related to
> others. The application appears to run more slowly with the CBO than with
> the rule based optimizer thus the live environment uses the RBO. The
> culprit appears to be when multiple aliases of the reference tables are
> used. The entire application is written in PL\SQL. I didn't write it.
>
> 1. Should the CBO *always* outperform the RBO.
> 2. Are clusters one instance this may not be the case.
> 3. Is Oracle really going to take away the RBO
>
> Tests suggest that rebuilding the tables without the cluster, computing
> stats and using CBO may not degrade performance but it takes courage to bite
> the bullet with the live system.
>
> Any thoughts appreciated.
>
> Jonathan
>
>
Received on Wed Jul 31 2002 - 09:51:14 CDT
