In an n-tier environment where there is an application server that is pooling database connections, viewing sessions may not provide the information yhou need to analyze performance. Grouping sessions into service names enables you to monitor performance more accurately. These two views provide the same information that their like-named session counterparts provide, except that the information is presented at the service level rather than at the session level:

• V$SERVICE_WAIT_CLASS shows wait statistics for each service, broken down by wait class.
• V$SERVICE_EVENT shows the same information as V$SERVICE_WAIT_CLASS, except that it is further broekn down by event ID.