Row-level locking

To support multi-user access, Derby utilizes row-level locking. However, you can configure Derby to use table-level locking in environments that have few concurrent transactions (for example, a read-only database) . Table-level locking is preferable if there are few or no writes to the server, while row-level locking is essential for good performance if many clients write to the server concurrently. The Derby optimizer tunes lock choice for queries automatically.

Related concepts
Multiple concurrency levels
Multi-connection and multi-threading
Administrative tools