Controls the optimizer’s inference of additional subquery predicates.
ON, OFF
ON
Can be set temporary for an individual connection or the PUBLIC group. Takes effect immediately. DBA permissions are not required to set this option.
INFER_SUBQUERY_PREDICATES controls whether the optimizer is allowed to infer additional subquery predicates from an existing subquery predicate through transitive closure across a simple equality join predicate. In most cases in which the optimizer chooses to make this inference, the query runs faster. There are some exceptions to this performance improvement, so you may need to experiment to be sure that this option is appropriate for your environment.
