JPA/Hibernate 乐观锁按版本插入场景

Question

I have a table which holds a balance of customers' balances.

| Customer_Id | Request_Id | Blance | Request_Date |

Each request that is received to the application, I select the last request and read its balance and do some process and finally insert a new record in the table with a new balance (Old Balance - Request Amount). My challenge is when two requests from one customer received to my application and concurrency occurred at this scenario and finally insert a record with the wrong balance. I know optimistic locking helps in update scenarios ideally, but our system is a legacy application, and I can't change the behavior of the system.

Answer 1

If you cannot use optimistic lock is not an option due to the legacy nature of your system you can still use pesimistic locking with JPA - The actual used depends on your implementation . Alternatively you can lock the rows you want to update with a NATIVE QUERY - for example in Oracle you can use SELECT ... FOR UPDATE :

SELECT ... FROM ... WHERE Customer_Id = ... FOR UPDATE

Answer 2

You can manage the optimistic lock, using @Version .

Example : Active optimistic lock management for Test table.

@Entity
@Table(name = "TEST")
public class TestEntity {

    private Long id;
    private String name;

    @Version
    private Long version;

   //getter and setters
}

More information about Optimistic-lock in JPA

By using this annotation, optimistic-lock will be managed automatically by the system and you don't need to do anything.

Notice that , If your table is full of data and it's not possible to drop and create it again, you must add version column to your table(by a native query).