ByThorben JanssenWhen we’re talking about performance optimizations for Spring Data JPA, the handling of associations is always an important topic. Because Spring Data JPA is based on JPA and most often used with Hibernate, you can apply all the performance tuning concepts you can find here on the blog. The most important one is to use…
ByThorben JanssenJPA and Hibernate provide 3 main options to map a Collection. If it’s a Collection of other entities, you can model it as a to-many association. This is the most common mapping. But you can also map it as an @ElementCollection or as a basic type. In this article, I will show you all 3…
ByThorben JanssenWhen you model a hierarchical data structure, you often have to use self-referencing associations. Both ends of these associations are of the same type. In other words, the entity object on which the association is defined and the one the association references are of the same type. In your database, you model that using a…
ByThorben JanssenAn association between 3 entities is called a ternary association. A typical example is an association between an employee, the project they are working on, and their role in that project. If the role is a complex object, you might decide to model this as 3 entity classes. The association between them is the interesting…
ByThorben JanssenYou probably learned that you should use FetchType.LAZY for all of your associations. It ensures that Hibernate initializes an association when you use it and doesn’t spend any time getting data you don’t need. Unfortunately, this introduces a new issue. You now need to use a JOIN FETCH clause or an EntityGraph to fetch the…