You can configure OCC or PCC for a bean as a whole or for transactions started by individual finder or business methods. By default, EAServer uses OCC with an all-values comparison for timestamp checking.
OCC allows greater scalability than PCC for most CMP entity beans. However, when using OCC, you must code your application to retry rejected updates, or you must enable automatic transaction retry for the application components.
PCC can perform better than OCC when your beans are mapped to tables with very high update contention. In these cases, the overhead of retrying transactions that fail due to update collisions can outweigh that caused by using database locks. If you have configured OCC, and see many “TRANSACTION_ROLLEDBACK: Optimistic Concurrency Control” messages in the server log, you should try PCC on the component identified in these messages.
