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How does an optimistic lock work?
Optimistic locking is when you check if the record was updated by someone else before you commit the transaction. Pessimistic locking is when you take an exclusive lock so that no one else can start modifying the record. You cannot combine optimistic locking with the automatic retry.
What is difference between optimistic and pessimistic locking?
Optimistic locking is used when you don’t expect many collisions. It costs less to do a normal operation but if the collision DOES occur you would pay a higher price to resolve it as the transaction is aborted. Pessimistic locking is used when a collision is anticipated.
How is the optimistic lock realized in MySQL?
Optimistic lock is realized by its own program, not by MySQL itself. Optimistic lock query is not locked, only the version number is checked when updating. For example, if we query that the version of the goods table is 1, then when updating this table, SQL will be
How is optimistic lock different from pessimistic lock?
To further view the lock information. Optimistic lock is different from pessimistic lock. Optimistic lock is realized by its own program, not by MySQL itself. Optimistic lock query is not locked, only the version number is checked when updating.
Is it possible to deadlock optimistic locking in SQL?
Typically, the user will make separate calls to retrieve the item and to save it, which may even be handled by different instances of your application in a cluster. Some sources claim that, when using optimistic locking, deadlocks are not possible because it never issues any database-level locks.
How to implement a pessimistic locking with JPA?
How to implement a pessimistic locking with JPA and some of the most popular RDBMS which you might be using in production: Oracle, MySQL and PostgreSQL; How to implement a pessimistic locking with JPA and in-memory databases which you might be using for integration tests: H2 and Apache Derby.