This OTN article explains why it is sometimes difficult for people to grasp the paradigm of writing good SQL which the Cost-Based-Optimized (CBO) can break down effectively. Often SQL-Statements are still written with the Rule-Based-Optimizer (RBO) in mind and that makes life very difficult for the CBO. This article helps to bring you up to date with what you should be thinking of when writing SQL statements for Oracle10g.
