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The cost-based optimizer would make a statistical
estimate for the tables that lacked statistics. If youare running an older Oracle
release using rules, you probably wonder if moving to a newer release with only costbased
optimizer support is a good idea. Let??™s have a closer look at the advantages of
the cost-based optimizer.
Newer database releases and the cost-based optimizer
The cost-based optimizer makes decisions with a wider range of knowledge about
the data structures in the database. Although the cost-based optimizer isn??™t flawless
in its decision-making process, it does make more accurate decisions based on its
wider base of information, especially because it has matured since its introduction in
Oracle7 and has improved with each new release.
The cost-based optimizer also takes into account improvements and new features in
the Oracle database as they are released. For instance, the cost-based optimizer
understands the impact that partitioned tables have on the selection of an execution
plan, while the rule-based optimizer did not.


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