Rule-based vs cost-based optimization

From: Chris <me_at_nospam.com>
Date: Thu, 26 Apr 2001 00:44:38 GMT
Message-ID: <WbKF6.14214$q51.148808_at_news1.gvcl1.bc.home.com>

Hope everyone can stand one more question on rule-based vs. cost-based optimization.

I know that Oracle recommends that new applications be developed with CBO and that Oracle has said that at some point RBO will no longer be supported. I also know that some advanced features in 8i won't work with RBO. Can anyone tell me if RBO is still supported in 9i?

We have had CBO as a default for years but I am finding that developers have been using the RULE hint here and there throughout various applications. They tell me that they just couldn't get decent performance using CBO. Does anyone know whether there are certain types of queries that give CBO trouble and what (in general) the characteristics of those queries are?

If anyone can help, TIA!!

--
Chris

Received on Thu Apr 26 2001 - 02:44:38 CEST

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