Optimizer features enabled
he optimizer_features_enable parameter shifts the behavior of the optimizer backwards to the specified release. The optimizer_features_enable is very useful when an execution plan changes after the application of a patch or the installation of a new release. You can set optimizer_features_enable at the system level (as an init.ora parameter), at the session level, and at the SQL statement level (as a hint, see below):
- SYSTEM = optimizer_features_enable='184.108.40.206'
- SESSION = alter session set optimizer_features_enable='220.127.116.11';
- SQL = select /*+ optimizer_features_enable('9.2.0') */