Re: OCP - Performance Tuning

"Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> wrote in message news:b15h9a$lqq$1$8300dec7_at_news.demon.co.uk...
>
>
> I've just been sent the following question from an OCP test,
> and I can't decide whether this is a subtle trap, or a naive
> interpretation of the manuals on the part of the examiner.
>
> I haven't been told whether this is a 'single answer only'
> question, or 'perm any N'. But I assume from the grammar
> that precisely one answer is supposed to be correct.
>
> If you were taking the exam, which one would you put ?
>
> (NB - I didn't say "which one is correct?").
>
> 4. The cost-based optimizer can choose between a nested
> loops join and a sort merge join operation. All tables are
> analyzed and the OPTIMIZER_MODE is set to FIRST_ROWS.
> Which execution plan will be the result?
>
> a. The sort-merge join.
> b. The nested loops join.
> c. This depends on some sort parameter values.
> d. This depends on the number of rows in each table.
>
>
>
> --
> Regards
>
> Jonathan Lewis

We all know that the correct answer is "e. It depends".

One assumes that the exam setters want you to say b, on the grounds that FIRST_ROWS should presumably give some favour to NL over SM.

All a load of nonsense really, given that there are so many other considerations, but I'm afraid I'm far too cynical to consider some deep trap-setting on the part of the examiner, as opposed to sheer incompetence.

But trying to second-guess what answer the examiner wants, instead of what is actually correct, IMHO just serves to illustrate what a farce this all is.

Regards,
Paul Received on Tue Jan 28 2003 - 14:27:42 CST