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How To Increment The Version Of The Locked Entity Even If This Entity Was Not Modified OPTIMISTIC_FORCE_INCREMENT

Description: This application is a sample of how OPTIMISTIC_FORCE_INCREMENT works in MySQL. This is useful when you want to increment the version of the locked entity even if this entity was not modified. Via OPTIMISTIC_FORCE_INCREMENT the version is updated (incremented) at the end of the currently running transaction.

Key points:

  • use a root entity, Chapter (which uses @Version)
  • several editors load a chapter and perform modifications mapped via the Modification entity
  • between Modification (child-side) and Chapter (parent-side) there is a lazy unidirectional @ManyToOne association
  • for each modification, Hibernate will trigger an INSERT statement against the modification table, therefore the chapter table will not be modified by editors
  • but, Chapter entity version is needed to ensure that modifications are applied sequentially (the author and editor are notified if a modificaton was added since the chapter copy was loaded)
  • the version is forcibly increased at each modification (this is materialized in an UPDATE triggered against the chapter table at the end of the currently running transaction)
  • set OPTIMISTIC_FORCE_INCREMENT in the corresponding repository
  • rely on two concurrent transactions to shape the scenario that will lead to an exception of type ObjectOptimisticLockingFailureException
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