Database locks are essential for maintaining _______ in multi-user environments, but they can also introduce bottlenecks and reduce scalability.

Concurrency control mechanisms such as database locks are crucial for maintaining data consistency in multi-user environments. They ensure that multiple users can access and modify data concurrently without causing conflicts or inconsistencies. However, excessive use of locks can lead to bottlenecks and reduce scalability as they may block other users from accessing data, impacting system performance.