java 16 lines · 5 steps

Killing N+1 queries with @EntityGraph in Spring

How Spring Data JPA repository methods eagerly fetch related entities in a single query using entity graphs.

Explained by highlit

Spring Intermediate orm fetching n+1-problem query-optimization jpa

1@Repository
2public interface OrderRepository extends JpaRepository<Order, Long> {
3 
4    @EntityGraph(attributePaths = {"customer", "lineItems", "lineItems.product"})
5    @Query("select o from Order o where o.status = :status")
6    List<Order> findByStatusWithDetails(@Param("status") OrderStatus status);
7 
8    @EntityGraph(attributePaths = {"customer", "lineItems"})
9    Optional<Order> findWithDetailsById(Long id);
10 
11    @EntityGraph(attributePaths = {"lineItems", "lineItems.product"})
12    Page<Order> findByCustomerId(Long customerId, Pageable pageable);
13 
14    @EntityGraph(value = "Order.withShipments", type = EntityGraph.EntityGraphType.LOAD)
15    List<Order> findByPlacedAtBetween(Instant from, Instant to);
16}

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STEP 01

Walkthrough

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Three takeaways

1@EntityGraph declares which associations to fetch eagerly per query, sidestepping the N+1 problem without changing entity mappings.
2attributePaths accepts dotted paths like lineItems.product to fetch nested associations several levels deep.
3Named entity graphs and LOAD versus FETCH types let you reuse and fine-tune eager-loading strategy across methods.

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