JPA hibernate executes multiple select query internally

Question

Problem Statement:in JPA hibernate I execute a method

Contact contact = entityManager.find(Contact.class, Integer.valueOf(contactId));

As expected EntityManager fires a select query to get an object of contact, but after that it fires another select query to get customer object which I do not want.
Customer object is an child object in contact object.
contact entiry has an foreign key customerId.

Requirment: I want entityManager to fire one select query get the contact object and do nothing after that no second select query neither a join query. contact object:

@Entity @Table(name = "contact") public class Contact { @JsonProperty("contactId") @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "Id") int contactId; @Column(name = "firstname") @JsonProperty("firstName") String firstName; @Column(name = "lastname") @JsonProperty("lastName") String lastName; @Column(name = "phone1") @JsonProperty("phone1") String phone1; @ManyToOne(optional = false, fetch = FetchType.LAZY, targetEntity = Customer.class) @JoinColumn(name = "customer_id", updatable = false) @Fetch(FetchMode.JOIN) Customer customer; public Customer getCustomer() { return customer; } public void setCustomer(Customer customer) { this.customer = customer; } }

No, it doesn't execute that query when executing find(). It most probably execute that query when you serialize the Contact to JSON: you didn't tell Jackson to avoid serializing the contct's customer, so Jackson serializes it, so Hibernate needs to execute a qery to load the state of the customer. — JB Nizet
– JB Nizet, Commented Dec 10, 2017 at 8:29

David Eibensteiner · Accepted Answer · 2017-12-11 10:36:47Z

I think your issue comes from using @Fetch(FetchMode.join) together with Lazy Loading. If you don't want to load the Customer eagerly then you should remove the @Fetch(FetchMode.join) and only use lazy loading

See more infos regarding this here (https://stackoverflow.com/a/29667050/2637940):

First of all, @Fetch(FetchMode.JOIN) and @ManyToOne(fetch = FetchType.LAZY) are antagonistic, one instructing an EAGER fetching, while the other suggesting a LAZY fetch.

Collectives™ on Stack Overflow

JPA hibernate executes multiple select query internally

1 Answer 1

Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Linked

Related