Concurrency control is the management of contention for data resources.
A concurrency control scheme is considered optimistic when locks are acquired
and released over a short period of time at the end of transaction. The objective
of optimistic concurrency control is to minimize the time over which
a given resource would be unavailable for use by other transactions.
The Mapping editor offers two optimistic concurrency control schemes for
EJB 2.x CMP entity beans:
Note: If you choose to use a collision
detection column, the use of the collision detection column will take precedence
over the alternative optimistic concurrency control scheme of including attributes
in a predicate for optimistic access intents. In addition, all the optimistic
predicate settings will be ignored for optimistic access intent.