Spring Boot JPA @EntityGraph, @NamedEntityGraph, and JOIN FETCH – Complete Guide with Examples
When working with Spring Boot JPA, the N+1 query problem can impact performance due to lazy loading. To optimize queries and fetch related entities efficiently, JPA provides @EntityGraph, @NamedEntityGraph, and JOIN FETCH . This guide walks you through their usage with practical examples, helping you write efficient, high-performance database queries in Spring Boot. 1. Introduction When working with JPA and Hibernate, N+1 query issues often arise due to lazy loading. @NamedEntityGraph and @EntityGraph provide a way to fetch related entities efficiently. JOIN FETCH is a JPQL technique that helps load associated entities in a single query. 2. Create a Spring Boot Project You can use Spring Initializr with: Spring Boot 3+ Dependencies: Spring Web, Spring Data JPA, Lombok, H2 Database 3. Define JPA Entities Department Entity (OneToMany with Employee) import jakarta .persistence .*; import lombok .Data ; import java .util .List ; @Data @Entity @Table (name = "departments...