Eager Fetch Type On Association (ARCH4060)

Key java.orm.eager-fetch-type-on-association · Severity warning · Category orm

Declaring an association fetch = EAGER at the mapping level fetches it needlessly on every query of the owning entity. Leave it LAZY by default and eager-load per query when needed.

Incorrect

@Entity
public class Order {
    @OneToMany(fetch = FetchType.EAGER) // items fetched on every Order query
    private List<LineItem> items;
}

Correct

@Entity
public class Order {
    @OneToMany(fetch = FetchType.LAZY)
    private List<LineItem> items;
}
// when needed: SELECT o FROM Order o JOIN FETCH o.items

Fix

Declare associations LAZY and selectively eager-load with JOIN FETCH in the queries that need them.