What is the purpose of an Access Lock?

An Access Lock plays a crucial role in managing database concurrency by allowing multiple users to read data while preventing them from writing to it. This type of lock ensures that while data can be accessed for reading, any write operations are temporarily restricted. Therefore, preventing Exclusive locks is an essential function of an Access Lock because Exclusive locks would completely block access to the data for other operations until the lock is released. By preventing Exclusive locks, Access Locks facilitate a balance where data can be read simultaneously by multiple users without the risk of conflicting write operations interfering.

In contrast, other options suggest various levels of access or restrictions that do not align with the fundamental purpose of an Access Lock. For instance, the concept of allowing all types of access would conflict with the intended restrictions of an Access Lock. Similarly, the aim to prevent Write locks is inaccurate because Access Locks are specifically designed to allow read operations while preventing modifications that would require a Write lock. Lastly, the notion of allowing Read locks only does not capture the true purpose, as Access Locks do not just permit Read locks—they actively prevent write operations while allowing concurrent reads.