You have the ability to either eagerly or lazily fetch associated entities. The fetch parameter can be set to FetchType.LAZY or FetchType.EAGER. EAGER will try to use an outer join select to retrieve the associated object, while LAZY will only trigger a select when the associated object is accessed for the first time. @OneToMany and @ManyToMany associations are defaulted to LAZY and @OneToOne and @ManyToOne are defaulted to EAGER. For more information about static fetching, check Section 3.4.5.1, “Lazy options and fetching modes”.

The recommanded approach is to use LAZY onn all static fetching definitions and override this choice dynamically through JPA-QL. JPA-QL has a fetch keyword that allows you to override laziness when doing a particular query. This is very useful to improve performance and is decided on a use case to use case basis.