The difference between a database optimistic lock and a pessimistic

1: Update, delete operations on the same resource for multiple users

2: Two kinds of locks are when the data resource operation conflict, and finally due to the reason of the lock, to ensure that the resources are not chaotic.
Optimistic Lock: Allows multiple people to operate a record at the same time, who commits first, records change to WHO, subsequent submissions fail
Pessimistic lock: Allows a person to operate a single resource, who first comes in, who first occupies resources. The need to wait for subsequent access

3: Pessimistic locking requires a persistent database connection, which is virtually nonexistent in today's Web applications

4: The emergence of an optimistic lock is a solution to maintain data accuracy in a short-term web-like business

The difference between a database optimistic lock and a pessimistic