Use @EntityGraph for Fetch Joins

Spring Data JPA supports @EntityGraph to fetch associations in a single query:

@EntityGraph(attributePaths = {"courseModules"})
List<CourseEntity> findAll();

This tells Spring Data to generate a JOIN FETCH under the hood.

Use JPQL with JOIN FETCH

If you're writing custom queries, use JOIN FETCH to eagerly load associations:

@Query("SELECT c FROM CourseEntity c JOIN FETCH c.courseModules")
List<CourseEntity> findAllWithModules();

This avoids the N+1 problem by fetching all data in one query.

Avoid fetch = FetchType.EAGER

Using EAGER by default can lead to unexpected behavior and performance issues. Prefer LAZY and control fetching explicitly via queries or entity graphs.

Use @BatchSize (Hibernate-specific)

If you must use lazy loading, you can reduce the number of queries using batching:

@OneToMany(mappedBy = "courses", fetch = FetchType.LAZY)
@BatchSize(size = 10)
private Set<CourseModules> courseModules;

This tells Hibernate to fetch related entities in batches instead of one-by-one.