JPA Optimistic Locking With @Version

JPA Optimistic Locking With @Version

• 1.
  JPA Optimistic Locking With@Version Albert Guo [email protected]
• 2.
  Problem No Task Time 12 3 4 1 User A read row 2 2 User B read row 2 3 User A update row 2 4 User B update row 2 2 Two users try to update the same data, it may cause the later user will process out-of-date (stale) data. User B may assigned new values to row 2 based on out-of-date information.
• 3.
  Optimistic Locking • Acommon strategy for avoiding stale data is to implement optimistic locking, and store the optimistic lock values in the object. • When a user attempts to write a change, the application checks to ensure the data has not changed since the user read the data. 3
• 4.
  OptimisticVersion Locking • Usethe @Version annotation to enable the JPA-managed optimistic locking by specifying the version field or property of an entity class that serves as its optimistic lock value (recommended). 4
• 5.
  DEMO – HOWTO ENABLE JPA OPTIMISTICVERSION LOCKING 5
• 6.
  Create a tablewith version column 6
• 7.
  Create entity 7 JPA provideautomatic support of row versioning via the @Version annotation. When you have entity with @Version annotated field or property, optimistic locking will be enabled automatically. The version field or property type must either be a numeric type (such as Number, long, int, BigDecimal, and so on), or a java.sql.Timestamp. We recommend using a numeric type.
• 8.
  Save new entity 8
• 9.
  Save new entity– cont. 9 JPA will maintain version value automatically
• 10.
  Update entity 10
• 11.
  Update entity –cont. 11 JPA will maintain version value automatically. The version value will increment by 1, from 1 to 2.
• 12.
  DEMO – OPTIMISTIC LOCKEXCEPTION 12
• 13.
  Scenario 13 No Task Time 12 3 4 1 User A read row 2 2 User B read row 2 3 User A update row 2 4 User B update row 2 Task #1 Task #2
• 14.
  Scenario – cont. 14 NoTask Time 1 2 3 4 1 User A read row 2 2 User B read row 2 3 User A update row 2 4 User B update row 2 Task #3 Task #4
• 15.
  OriginalValue 15
• 16.
  Update entity 16 No TaskTime 1 2 3 4 1 User A read row 2 2 User B read row 2 3 User A update row 2 4 User B update row 2 Task #1 Task #2
• 17.
  Update entity –cont. 17 No Task Time 1 2 3 4 1 User A read row 2 2 User B read row 2 3 User A update row 2 4 User B update row 2 Task #3 Task #4 Owing to user A had updated successfully, the version value had been update to 3. User B do update based on version value 2 (based on stale information), so JPA will throw OptimisticLockException.
• 18.
  Update entity –cont. 18 The color had been updated to GREY, and the version value had been updated incrementally from 2 to 3.