Controls the optimizer’s inference of additional subquery predicates.
Option can be set at the database (PUBLIC) or user level. When set at the database level, the value becomes the default for any new user, but has no impact on existing users. When set at the user level, overrides the PUBLIC value for that user only. No system privilege is required to set option for self. System privilege is required to set at database level or at user level for any user other than self.
Requires the SET ANY PUBLIC OPTION system privilege to set this option. Can be set temporary for an individual connection or for the PUBLIC role. Takes effect immediately.
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.