What is the significance of the default loading strategy in Hibernate for associated entities?

In Hibernate, the default fetch strategy for associated entities depends on the type of association:

• For @ManyToOne and @OneToOne associations, EAGER fetching is used by default, meaning related entities are loaded immediately along with the main entity.

• For @OneToMany and @ManyToMany associations, LAZY fetching is used by default, meaning related collections are loaded only upon first access.

This behavior can be overridden using the @FetchType.LAZY or @FetchType.EAGER annotations.

Example:

@Entity
public class Order {
    @ManyToOne(fetch = FetchType.EAGER) // default
    private Customer customer;

    @OneToMany(fetch = FetchType.LAZY) // default
    private List<OrderItem> items;
}

Thus, Hibernate optimizes data loading by either loading related objects immediately or on demand, depending on the association type.