Re: Cost-Based or Rule-Based?

What version of Oracle were you using when you found these results?

In every DB and in every application CBO was always better?

When we searched Oracle's support site and the net we found dozens of user reports and even some actual Oracle logs showing V7.2 and 7.3's CBO had made the wrong index pick and the performance was WORSE than RBO.

>CBO without any doubts is better than RBO. At our site we have several
Oracle DBs
>
>and PeopleSoft applications that were optimized for RBO. Switching
optimization
>mode for slow SQL expressions increased speed in 50-2000 times.
>I had one expression that in RBO mode ran for 3h 5 min, in CBO - 5 sec.
Received on Sun Jan 24 1999 - 21:48:33 CST