Re: index_desc hint question

On Sun, 25 Mar 2001 06:21:27 GMT, Julian Htun <jhtun_at_kc.rr.com> wrote:

>I'm using Oracle 7.3.3 and Rule Base optimization as default. I can do
>analyze with estimate statistics once a month. I have this index and

There is no point in doing analyze if you're running RULE based as default. All hints and stats *will* be ignored!

Now, *assuming* you have CHOOSE instead of RULE and you run stats:
>
>1) Can I 100% rely on Oracle that it will always use that index and scan
>in a DESC order?

Yes, regardless of what anybody else has told you.

>2) What effect will I get if somehow analyze is not performed? Will
>Oracle still use this index and scan in DESC order?

Most probably not. Particularly if you have CHOOSE and you drop the stats.

>3) Can you guys think of any reason why and how Oracle might not scan
>the index in DESC order? This is a pretty important system (sale is
>just an example), and out of order is really bad.
>

A bug^H^H^Hfeature?

Cheers
Nuno Souto
nsouto_at_bigpond.net.au.nospam
http://www.users.bigpond.net.au/the_Den/index.html Received on Sun Mar 25 2001 - 03:47:30 CST