Re: Rule Based Optimization Going Away?

"Hints" are directives.

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.

--
Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

Next Seminar dates:
(see http://www.jlcomp.demon.co.uk/seminar.html )

____USA__________November 7/9   (Detroit)
____USA__________November 19/21 (Dallas)
____England______November 12/14

The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html





Pablo Sanchez wrote in message ...


>"Howard J. Rogers" <howardjr2000_at_yahoo.com.au> wrote in

>news:7ZMm9.45097$g9.128606_at_newsfeeds.bigpond.com:

>

>> Anyway, whether I believe you or not: by 10i, the rule-based

>> optimizer is finished. So even if you are the God's gift to

>> predicting access paths, tough luck: Oracle won't support you.

>

>The 'problem' as I see it as the an optimizer is a piece of complex

>code.  Sybase's ASE optimizer has been around _way_ longer than

>Oracle's and it is extremely robust.  However, it still has the

>occasional bug.

>

>What I'd like to see in 10i is for Oracle to support not hints but

>optimizer directives because bugs do happen.

>--

>Pablo Sanchez, High-Performance Database Engineering

>http://www.hpdbe.com