Re: 8i to 9i migration, performance issues

From: Daniel Roy <danielroy10junk_at_hotmail.com>
Date: 12 Mar 2004 10:52:57 -0800
Message-ID: <3722db.0403121052.3fab5f0e@posting.google.com>

> Do we loose features of 9i, if we set this parameter?
> optimizer_feature_enable=817
>
> CBO in 9i is different then CBO in 8i?
>

By looking at http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96536/ch1136.htm#1020706, here's what you lose by setting optimizer_feature_enable to 817:

Peeking at user-defined bind variables
Index joins
Subquery unnesting

Only you (and your developers) know if you care or not about these features. I personally don't think it's a good idea to invest on a database upgrade, and then on purpose try to avoid the new features. I would instead take a look closer at one of the queries running slowly, to see what's the cause.

Just my 2 cents

Daniel Received on Fri Mar 12 2004 - 12:52:57 CST