JPA Hibernate Change Fetch type from Lazy To Eager for multiple child entities based on condition

Question

Parent Entity

• Product

  public class ProductEntity extends BaseEntity { private static final long serialVersionUID = 1L; @Id @Column(name = "id", nullable = false) @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; @Column(name = "product_uuid", nullable = false) private String uuid; @Column(name = "sku", nullable = true) private Long sku; @Column(name = "name", nullable = false) private String name; @OneToMany(mappedBy = "product", cascade = CascadeType.ALL, orphanRemoval = true) private Set<ProductInfoEntity> infos; @OneToMany(mappedBy = "product", cascade = CascadeType.ALL, orphanRemoval = true) private Set<ProductTaxEntity> taxes; }

Child Entity

• Info
• Tax

Only few cases child entities required to fetch eagerly. Is there any way to change child entity fetch type from lazy to eager in either of the framework JPARepository/ CriteriaQuery/SQL

Tried almost every solution on stack overflow but every-time code will hit many queries to retrieve child entities

Answer 1

It's called N+1 problem in hibernate, You can solve it by using below methodologies...

-> By using JOIN FETCH
-> By using @EntityGraph and Projection

Because JOIN FETCH will make always single query for multiple tables using join internally.