ByThorben JanssenMost databases put a lot of effort into analyzing SQL statements and finding the optimal execution plan. This often makes the difference between a slow and a blazing fast statement. But this analysis can also be rather complex. That’s why a lot of databases try to cache and reuse the created execution plans. Hibernate and…
ByThorben JanssenArrays are a common data type in Java and part of the SQL-99 standard. So, it should be easy and quite common to use them with Hibernate, right? No, they aren’t. Most developers try to avoid using arrays in their persistence layers. There are several reasons for that: Not all DBMS support arrays. Because of…
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 JanssenThe entity lifecycle model is one of the core concepts of JPA and all its implementations. Even though it’s not directly visible when working with JPA’s EntityManager, it affects all operations you perform. The different states of the model define how your persistence provider, e.g. Hibernate, handles your entity objects. This includes if it loads…
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…