Re: Horrible SELECT !!!!

From: Rniemic <rniemic_at_aol.com>
Date: 29 Jun 1999 19:40:18 GMT
Message-ID: <19990629154018.08643.00006094@ng-fa1.aol.com>

All of these are great suggestions. You can also use the ORDERED hint and change the order of the tables in the FROM clause ... this could make performance better or worse depending on how well it is being driven now. The syntax is as follows:

select /*+ ORDERED */ col1, col2
from a, b
where ...
(the above drives with a to the b table in a nested loops join)

select /*+ ORDERED */ col1, col2
from b,a
where ...
(the above query drives with b to a in a nested loops join)

The type of join will also affect which table truly goes first ... I spent several weeks just writing about this.

Rich Niemiec
Oracle Performance Tips and Techniques, Oracle Press ISBN: 0078824346 Received on Tue Jun 29 1999 - 14:40:18 CDT