Optimistic and Pessimistic locking in Ado.Net

Question

What is difference between optimistic and pessimistic locking.

Vulpes · Answer

Briefly: Pessimistic locking means that a user can't open a record for editing if another user has already opened it. You'd use this when the chance of a conflict between users is high. The drawback is that it may involve users having to be queued to access a particular record. Optimistic locking means that multiple users can open a record for editing at the same time. You'd use this when the chance of a conflict between users is low. Before your update is saved a check is made to see whether any other user has updated it in the meantime and if that's the case your update is rolled back and an error is thrown.