Re: separate data/inidex

In article <aam0i3091q_at_drn.newsguy.com>, you said (and I quote):
> tons of them think the most discriminating field needs to go first in an index
> and so on....

this is an interesting one. I can't for the life of me remember when this was ever true (as in which version)? I've always measured it not to be so in ALL versions of Oracle I worked with, since V4. Did I miss a long series or is this another big myth from the start? It just doesn't make sense at all to do it this way when one reads how concat indexes are processed and stored.

> > If they find it help performance
> >they keep doing it. Otherwise they stop.
>
> I find NEITHER to be true.
>
> A) they never measure it
> B) they *never* stop.

too true.
unfortunately a lot of them do a lot by rote, rather than by need. number of times I've been crucified at sites for saying that defrag to 1 extent is a waste of time is not even fun! Since V6 it hasn't really been needed. All we had to do back then was set the right values for dc_used_extents and dc_free_extents and bingo: all objects could live with a (reasonable!) number of extents without any impact on performance. Problem was no-one ever changed the default values of these two, which were ridiculously small. Hence the whole myth started. And kept going all the way through 7.0, 7.1, etc etc, where these parameters were autoset  by Oracle to huge values and the problem disappeared.

-- 
Cheers
Nuno Souto
nsouto_at_optushome.com.au.nospam