What is pessimistic locking in ORMs?

What is pessimistic locking in ORMs?

Pessimistic locking is a concurrency control mechanism used in Object-Relational Mappers (ORMs) to prevent conflicts when multiple transactions try to access the same data. It locks the data for a transaction, ensuring that no other transaction can modify it until the lock is released.

How does it differ from optimistic locking?

Unlike pessimistic locking, which locks data for the duration of a transaction, optimistic locking allows multiple transactions to access the same data simultaneously. It checks for conflicts only at the time of committing the transaction, which can lead to fewer locks and better performance in low-contention scenarios.

What are the advantages of using pessimistic locking?

The main advantages of pessimistic locking include preventing lost updates, ensuring data integrity, and avoiding conflicts in high-contention environments where multiple transactions frequently access the same data.

Are there any downsides to using it?

Yes, the downsides include potential performance bottlenecks due to increased waiting times for locks, and the risk of deadlocks if not managed properly. It can also lead to reduced concurrency.