Re: Performance and table order

From: Robert Risholm <risholmr_at_j51.com>
Date: 1997/07/04
Message-ID: <ECs2xn.LAp@nonexistent.com>#1/1

>My Environment: Oracle 7.3, SQL*Net/Plus 2.3 on Windows NT 4.0.
>
>I'm just getting into the Oracle mysteries and found an
>interesting and irritating issue:
> (clip)
>Can anyone explain this to me ? How can I determine the optimal
>table order in a query (if this is possible) ?

Oracle 7.3 supports a COST based optimizer. The "order" of your statements will have no bearing on the execution path Oracle takes, it will make the decision based upon statistics.

It appears you are using the RULES based optimizer used prior to 7.3. (Or possibly you have not run statistics for the COST based optimizer??)

The COST based optimizer in my experience is very good at choosing the most efficient execution path. I recommend you have the COST based optimizer selected as the default for environment. Run ANALYSE STATISTICS on a regular basis. Received on Fri Jul 04 1997 - 00:00:00 CDT