Oracle OBIEE passing middle-tier user to database

When querying using OBIEE to Oracle database the connection pool username is passed to the database. To also pass the middle-tier user name you need to set the user identifier on the session. TO do this in OBIEE, open the RPD, edit the connection pool settings and create a new connection script to run at connect time.

Add the following line to the connect script -

call dbms_session.set_identifier('VALUEOF(NQ_SESSION.USER)')

This will then be available as the CLIENT_ID attribute when querying session history and also be available in the audit trail on queries.
EG. Select sid, client_identifier from v$session