Hi Dean, UL is a user lock...you're doing it to yourself. ;-) Look for code in your application that uses DBMS_LOCK calls. The DBMS_LOCK API is an interface to allow users and applications manage locking through the same enqueue/lock mechanisms that Oracle uses internally. But, every lock created/managed by DBMS_LOCK will be of type 'UL'. Hope that helps, -Mark -- Mark J. Bobak Senior Database Administrator, System & Product Technologies ProQuest 789 E. Eisenhower, Parkway, P.O. Box 1346 Ann Arbor MI 48106-1346 734.997.4059 or 800.521.0600 x 4059 mark.bobak@xxxxxxxxxxxxxxx <mailto:mark.bobak@xxxxxxxxxxxxxxx> www.proquest.com <http://www.proquest.com/> www.csa.com <http://www.csa.com/> ProQuest...Start here. ________________________________ From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Dean Richards Sent: Monday, June 11, 2007 12:31 PM To: oracle-l@xxxxxxxxxxxxx Subject: enq: UL - contention Wait Event Does anyone know what the wait event named "enq: UL - contention" means? There is nothing in Metalink or anywhere that I can find that gives the definition. I have a session that waits more than 90% of its time on this event. Thanks.