Re: Stored outline internals

Nuno Souto wrote:
>
> In a valiant and sublime effort,Connor McDonald
> frowned, dipped a thumb in soot and doodled:
>
> >
> >INDEX(emp emp_ix)
> >FULL(dept)
> >RULE
> >
> >The question is: If the rule optimizer has not changed since version
> >"blah", surely then, just the RULE hint would suffice
>
> weeeeeel, I don't want to sound discordant but I've seen instances
> where RULE and INDEX were used to convince a particularly reluctant
> optimizer to actually pick up an index. 8.0.6 was the last time I saw
> them.
>
> There is so little detailed doco on the changes to the optimizer since
> 7.3.3 that it's almost impossible to definitively say "what works with
> who"...
>
> >
> >Alternatively, I've yet to generate an SQL where the hints *other* than
> >the RULE hint are not sufficient to force the expected plan which would
> >suggest the 'RULE' is superfluous
>
> I can send you a few examples, all in Peoplesoft, where RULE was the
> only option. However, I'd say you're quite right: given a bunch of
> other hints, then RULE would appear to be redundant. Yet, one never
> knows: with all the "hidden" changes to optimizer rules that have been
> taking place over the last 4 or so years.
>
> Cheers
> Nuno Souto
> nsouto_at_optushome.com.au.nospam

... and in fact, I've thought of the reason myself. By having all the explicit hints, then you cater for the situation where you later add indexes. Just having RULE would not be enough in this instance.

Cheers
Connor

-- 
==============================
Connor McDonald

http://www.oracledba.co.uk

"Some days you're the pigeon, some days you're the statue..."