Re: Rule Based Optimization Going Away?

"Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> wrote in news:angshf$dn$1$8300dec7_at_news.demon.co.uk:

>
> "Hints" are directives.

Are we splitting hairs? I look at a directive as a command: you _will_ do this. That is, override what you _think_ is the right thing to do and do what I say. :)

> There are bugs around., and there are plenty
> of reasons why the hints given are deemed
> to be irrelevant (the smarter the CBO gets,
> the more precise your hinting has to be).
>
> A hint basically says:
> IF you are about to take action X
> then the only option you have is Y
>
> This can be confirmed by reviewing
> 10053 trace files.
>
> However, Oracle is often capable of avoiding
> action X and therefore appears to have ignored
> the hint.

Yup, I understand. The point remains that the RBO is not perfect and will not be perfect. It will make errors because after all, it's coded by us humans. I cited the Sybase ASE CBO because it's more mature than Oracle's and yet, it too has the occasional bug. As Oracle's matures, one can assume that it will have bugs as well.

What I want is control to override the CBO and to review the trace files to confirm or deny whether I've told it to auger itself or have helped things along.

-- 
Pablo Sanchez, High-Performance Database Engineering
http://www.hpdbe.com


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