Pessimistic lock and optimistic lock of MySQL

Interview questions ：mysql The lock of pessimism and the lock of optimism

Pessimistic locking , Because this is a pessimistic way of concurrency control for data modification . We generally think that data is more likely to be modified concurrently , So we need to lock it before we modify it .

Optimism lock , When processing the database , Optimistic locks do not use the lock mechanism provided by the database . The general way to implement optimistic locking is to record the data version （version）.