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So with JPA/Hibernate you can certainly load an entity "proxy" without hitting the database using something like session.load() or entityManager.getReference().
However, it seems it's impossible to set a property on these "proxies" without Hibernate initializing the proxy from the database. Therefore, you can't persist just the changed values (via @DynamicUpdate on the entity) without a select.
I believe this is just the way it is and if you want update without select you have to roll it yourself. I'd be delighted if somebody could prove me wrong! Am I missing something?
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Using the @Modifying Annotation As we can see, this method returns an integer. It's a feature of Spring Data JPA @Modifying queries that provides us with the number of updated entities.
No. Strictly speaking, Hibernate does not send an SQL update on update . update simply updates the object in the current session. Hibernate executes queries when the session is flushed.
JPA can be used without a JPA provider aka Hibernate, EclipseLink and so on only if the application server has already a JPA implementation.
You cant actually use both of them in the same application. For backwards compatibility. We are expanding our application and want to start using Spring Data JPA, but still keep the old hibernate implementation. Its better you develop your new application as a separate microservice and use spring data jpa ..
I'm afraid you are correct, as written in the java-doc of @DynamicUpdate: "Note, for re-attachment of detached entities this is not possible without select-before-update being enabled."
The answer given by nicolasl is not correct for this case, implementing persistable is required if you wish to control whether persist or merge is triggered when using CrudRepository.save()
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