Description: Bulk operations (updates and deletes) are fastest than batching, can benefit from indexing, but they have two main drawbacks:
- bulk updates/deletes may leave the Persistent Context in an outdated state (prevent this by flushing the Persistent Context before update/delete and close/clear it after the update/delete to avoid issues created by potentially unflushed or outdated entities)
- bulk updates/deletes don't benefit of application-level optimistic locking mechanisms, therefore the lost updates not prevented (it is advisable to signal these updates by explicitly incrementing
version(if any is present)).
This application provides examples of bulk updates for Author and Book entities (between Author and Book there is a bidirectional lazy @OneToMany relationship). Both, Author and Book, has a version field.
Key points:
- this application provide an example of bulk updates that don't involve entities (data is not loaded in the Persistent Context)
- this application provide an example of bulk updates that involve entities (data is loaded in the Persistent Context before update it via bulk operations)
