Re: OCP - Performance Tuning

empirically : I see NL (&HJ) over SM so much that it'd be B . However if we are supposed to use our heads :

: No version given then assume current .. 9.2 (or a version prior to HJ enablement)
: why has HJ been ruled out (PGA_A_T miniscule ? ) ? should this affect our deductive process ?
reading the question if we assume current versions & FIRST_ROWS won't an NL join type have the best chance of getting to any matching row first cause SM's gotta do a sort or two prior.

CBO knows the stats. ....

so B again. ...

The only corollary I can see is the lack of places then where SM would ever be used over HJ/NL

"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
> http://www.jlcomp.demon.co.uk
>
> Coming soon a new one-day tutorial:
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Received on Tue Jan 28 2003 - 04:42:38 CST