Re: Migrating to cost based optimizer

From: Sybrand Bakker <postbus_at_sybrandb.demon.nl>
Date: Sat, 23 Sep 2006 19:58:33 +0200
Message-ID: <k8tah2h5589sgj6f4eq42rne85330bellc@4ax.com>

On 23 Sep 2006 10:41:47 -0700, hasta_l3_at_hotmail.com wrote:

>
>We wonder whether the cost based optimizer may one day decide to use a
>suboptimal plan at a customer site thousand kilometers away, and how to
>make sure this won't happen...

Usually applications have lookup tables and fact tables. Obviously the former have few records and the latter many records. As soon as the ratio changes dramatically you have the biggest chance for changing plans.
This is the main reason why you should test your applications with a reasonable amount of fact records, ie with a realistic ratio.

--
Sybrand Bakker, Senior Oracle DBA

Received on Sat Sep 23 2006 - 12:58:33 CDT