Feed?
Mmmmm Duff!
HJR
--
Oracle Resources : http://www.geocities.com/howardjr2000
========================================
"Nuno Souto" <nsouto_at_optushome.com.au.nospam> wrote in message
news:3bdfca54.2484163_at_news...
> In a valiant and sublime effort,Howard J. Rogers
> frowned, dipped a thumb in soot and doodled:
>
> >Indexing as X, Y, Z might actually be preferable, because with the low
> >selectivity columns first, you can use index key compression, and get
much
> >more compact indexes (and hence much lower I/O) than you might otherwise
> >manage. That's assuming you have at least 8i, of course.
>
> I'd go along with that too. The only case is where the vast majority
> of SQL predicates use only Y and Z or Y alone, in which case the index
> won't be picked up unless the predicates are tweaked. Then again,
> enter 9i and all that changes.
>
>
> >
> >The old myth about the most selective column needing to be first is just
> >that -a myth. Hasn't been true for ages.
>
> I don't even know where the heck that one came from! I've NOT ONCE
> had good results with it and I've been using ORACLE since V4!
>
> Must have been another one of those "benchmarks" done without the
> slightest control and quoted out of context, so widespread a few years
> ago amidst the "cognoscenti". Those things have done more damage to
> proper tuning and use of ORACLE than the entire competition put
> together...
>
>
> >
> >9i has skip scanning of indexes which means searches for non-leading keys
> >can be done efficiently, so that shouldn't be a major issues there.
>
> Hale-luia!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>
>
> >
> >Just my first thoughts. I may have seconds, though.
> >
>
>
> Me 2. Nothing like a good feed! ;-)
>
>
> Cheers
> Nuno Souto
> nsouto_at_optushome.com.au.nospam
Received on Wed Oct 31 2001 - 04:10:42 CST
