What are the types of locks in databases?

What are the types of locks in databases?

In databases, there are several types of locks, including shared locks, exclusive locks, and update locks. Shared locks allow multiple transactions to read a resource, while exclusive locks prevent other transactions from accessing the resource until the lock is released. Update locks are used to prevent deadlocks when a transaction intends to update a resource.

Can you explain shared and exclusive locks in more detail?

Sure! A shared lock allows multiple transactions to read a resource simultaneously, but no transaction can modify it until all shared locks are released. An exclusive lock, on the other hand, is used when a transaction needs to write to a resource. It prevents other transactions from reading or writing to that resource until the exclusive lock is released.

What happens if a transaction tries to access a locked resource?

If a transaction tries to access a locked resource, it will be blocked until the lock is released. This ensures data integrity and prevents conflicts between transactions.

Are there any drawbacks to using locks in databases?

Yes, while locks are essential for maintaining data integrity, they can lead to performance issues such as deadlocks and reduced concurrency if not managed properly.