By default, Spring Data JPA loads related data lazily, which can cause the N+1 problem — one query for the main data and more for each related item. @EntityGraph annotation fixes this by letting you load related data in a single query, without changing your entity mapping. It’s simple, improves performance, and avoids writing custom JOIN FETCH queries.
Example
Let’s say you have a Post entity that references an Author.
Entities
@Entity
public class Post {
@Id
private Long id;
private String title;
@ManyToOne(fetch = FetchType.LAZY)
private Author author;
}
@Entity
public class Author {
@Id
private Long id;
private String name;
}
Repository
public interface PostRepository extends JpaRepository<Post, Long> {
// attributePaths specifies related entities to eagerly load
@EntityGraph(attributePaths = {"author"})
List<Post> findAll();
}
Now, if you create a simple controller to return all posts and have SQL logging enabled, you'll see the queries printed in the console.
With @EntityGraph, only one query runs to fetch both the post and its author. Without it, multiple queries are executed — one for the posts and one for each author — which is the N+1 problem.
✅ Using @EntityGraph
Only one query — fast and efficient.
select p.id, p.title, a.id, a.name
from post p
left join author a on p.author_id = a.id
🚨 Not Using @EntityGraph
N+1 queries — slow and wasteful.
select * from post;
select * from author where id = ?;
select * from author where id = ?;