Hibernate is a great Object Relational Mapping (ORM) library for accessing data in a relational database. It is one of the leading implementations of Java Persistence (formerly known as JPA). Using JPQL (based on HQL, which is still a nice syntax guide) one can access and update the data in the database through your ORM objects in a simplified SQL way. However, when implemented incorrectly one can run into serious performance problems. They can all be avoided though. Here are some important things to consider to make your queries performant.