Hibernate performance tuning

In the preceding section, we saw common Hibernate traps or issues. These issues don't necessarily mean faults in Hibernate; sometimes, they are from incorrect usage of the framework, and in some cases, limitations of the ORM framework itself. In the following sections, we will see how to improve performance in Hibernate.

Approaches to avoid the n + 1 problem

We already saw the n + 1 problem in the Hibernate n + 1 problem section. Too many queries will slow down our application's overall performance. So, in order to avoid these additional queries with lazy loading, let's see what options are available.

Fetch join using JPQL

Normally, we call the findById method of DAO to fetch the outer or parent entity and then call the getter methods of associations. Doing so leads to n + 1 queries because the framework will execute additional queries for each association. Instead, we can write a JPQL query using the createQuery method of EntityManager. In this query, we can join...