You can use ROLLBACK or ROLLFORWARD statements to recover base tables that have join indexes defined on them; however, the join indexes are not rebuilt during the recovery process. Instead, they are marked as not valid. You must drop and recreate any such join indexes before the Optimizer can use them again to generate a query plan.
When a join index has been marked not valid, the SHOW JOIN INDEX statement displays a special status message to inform you that the join index has been so marked.