How to avoid JPA persist directly insert into database? - jpa

Question

This is the mysql table.
create table Customer
(
id int auto_increment primary key,
birth date null,
createdTime time null,
updateTime datetime(6) null
);
This my java code
#Before
public void init() {
this.entityManagerFactory=Persistence.createEntityManagerFactory("jpaLearn");
this.entityManager=this.entityManagerFactory.createEntityManager();
this.entityTransaction=this.entityManager.getTransaction();
this.entityTransaction.begin();
}
#Test
public void persistentTest() {
this.entityManager.setFlushMode(FlushModeType.COMMIT); //don't work.
for (int i = 0; i < 1000; i++) {
Customer customer = new Customer();
customer.setBirth(new Date());
customer.setCreatedTime(new Date());
customer.setUpdateTime(new Date());
this.entityManager.persist(customer);
}
}
#After
public void destroy(){
this.entityTransaction.commit();
this.entityManager.close();
this.entityManagerFactory.close();
}
When I reading the wikibooks of JPA, it said "This means that when you call persist, merge, or remove the database DML INSERT, UPDATE, DELETE is not executed, until commit, or until a flush is triggered."
But at same time my code runing, I read the mysql log, I find each time the persist execution, mysql will execute the sql. And I also read the wireShark, each time will cause the request to Database.
I remember jpa saveAll method can send SQL statements to the database in batches? If I wanna to insert 10000 records, how to improve the efficiency?

Answer 1

My answer below supposes that you use Hibernate as jpa implementation. Hibernate doesn't enable batching by default. This means that it'll send a separate SQL statement for each insert/update operation.
You should set hibernate.jdbc.batch_size property to a number bigger than 0.
It is better to set this property in your persistence.xml file where you have your jpa configuration but since you have not posted it in the question, below it is set directly on the EntityManagerFactory.
#Before
public void init() {
Properties properties = new Properties();
properties.put("hibernate.jdbc.batch_size", "5");
this.entityManagerFactory = Persistence.createEntityManagerFactory("jpaLearn", properties);
this.entityManager = this.entityManagerFactory.createEntityManager();
this.entityTransaction = this.entityManager.getTransaction();
this.entityTransaction.begin();
}
Then by observing your logs you should see that the Customer records are persisted in the database in batches of 5.
For further reading please check: https://www.baeldung.com/jpa-hibernate-batch-insert-update

Answer 2

you should enable batch for hibernate
spring.jpa.properties.hibernate.order_inserts=true
spring.jpa.properties.hibernate.order_updates=true
spring.jpa.properties.hibernate.jdbc.batch_size=20
and use
reWriteBatchedInserts&reWriteBatchedStatements=true
end of your connectionString