A beginner’s guide to Hibernate flush operation order
Introduction As explained in this article, Hibernate shifts the developer mindset from SQL to entity state transitions. A JPA entity may be in one of the following states: New/Transient: the entity is not associated with a persistence context, be it a newly created object the database doesn’t know anything about. Persistent: the entity is associated with a persistence context (residing in the 1st Level Cache) and there is a database row representing this entity. Detached: the entity was previously associated with a persistence context, but the persistence context was closed, or the… Read More
How do Set and List collections behave with JPA and Hibernate
Introduction Hibernate is a great ORM tool, and it eases development considerably, but it has a lot of gotchas you must be aware of if you want to use it properly. On medium to large projects, it’s very common to have bidirectional parent-child associations, which allow us to navigate both ends of a given relationship. When it comes to controlling the persist/merge part of the association, there are two options available. One would be to have the @OneToMany end in charge of synchronizing the collection changes, but this is an inefficient approach…. Read More
Lock processing logic by customer
Introduction In the current application we are developing there was one use case where we wanted to synchronize message processing by message provider (customer generating those messaging). The flow looks something like this: So messages may come randomly since there are more customer jobs running in parallel, but we want to ensure that messages belonging to the same customer are processed one after the other (analog to the Serializable database isolation level) while allowing messages coming from different customers to be processed in parallel.
