Re: Cost-Based or Rule-Based - What's Your Experience

I wouldn't go to cost-based as a default without testing all typical queries and adding hints where necessary. I've seen huge performance degradation result from simply analyzing tables and enabling cost optimization. Don't just analyze tables, turn on cost optimization, and forget about it. You'll almost surely find some operations are much slower. Test your queries, and use hints. Also be aware that the optimizer frequently ignores hints, so be sure to get query plans to verify that the optimizer is doing what you want it to do.

If this seems like too much trouble, stick with the rule-based optimizer until Oracle gets its act together. Received on Mon Aug 28 1995 - 00:00:00 CEST