JDBC defines the following concurrency types for a result set:
• Read-only
• Updatable
A read-only result set does not allow its contents to be updated. Read-only result sets can increase the overall level of concurrency between transactions, because multiple read-only locks can be held on a data item simultaneously.
An updatable result set allows its contents to be updated and may use database write locks to mediate access to the same data item by different transactions. Because only a single write lock may be held at one time on a data item, updatable result sets can reduce concurrency.
An optimistic concurrency control scheme may be appropriate if you can accurately predict that conflicting access to data will seldom occur. Typically, optimistic concurrency control implementations compare rows by a value or by a version number to determine if an update conflict has occurred.
