Optimistic Concurrency Control (OCC) helps increase database performance.Optimistic Concurrency only locks records from the time when the actual update is performed.
OCC makes it possible for other processes to update a record even after it has been fetched. You can catch update conflicts by catching the UpdateConflict andUpdateConflictNotRecovered exceptions.
Pessimistic Concurrency Control locks records as soon as they are fetched from the database for an update. However,
Pessimistic concurrency was the only option available in Microsoft Axapta 3.0 (now a part of Microsoft Dynamics).