Consistency of Catalog Information

Catalog information is represented by the instance of a catalog class/virtual class. If such information is accessed at the READ UNCOMMITTED INSTANCES (TRAN_REP_CLASS_UNCOMMIT_INSTANCE or TRAN_COMMIT_CLASS_UNCOMMIT_INSTANCE) isolation level, incorrect values (values being changed) can be read. Therefore, to get correct catalog information, you must use the SELECT query on the catalog class/virtual class at the READ COMMITTED INSTANCES isolation level or higher.