The Future of the Optimizer
This chapter clearly shows that the current optimizers are not optimal yet. In some cases, the optimizer cannot determine the most efficient processing strategy. This can lead to poor processing times. This applies not only to database servers with SQL as their database language, but also to any system that has to determine the processing strategy itself.
A lot of research is being carried out to improve optimizers. Experience shows that each new version of an SQL product is faster than its predecessor. This trend will continue in the years to come. One day, optimizers will always find better strategies than most human programmers. E. F. Codd, founder of the relational model, put it as follows [CODE82]: