when is Transaction used in hibernate?

[Tony Smith]

Hi I am new to hibernate, I was trying out some code, nothing gets written to the database. However if I surround my code inside begintransaction and commit, it works fine. So my question is, should most operations be done inside transaction? Or when should the transaction be used?

[Cameron Wallace McKenzie]

Welcome to your first schooling in Hibernate.

The word transaction can be literally defined as a "unit of work." Is connecting to a database, querying its data, and getting back some information work? I'm sure the database would think so.

So yes, you always need a transaction. You are always doing work.

Now, when we think of transactions, we often think of the ACID properties of a transaction, and rolling things back, and commits, and stuff like that, and you certainly don't need all that with a read, or something simple, but that doesn't mean you're not transacting with the database.

So yes, you always need a transaction.

A person named Christian Bauer, someone who might know a little bit about Hibernate, wrote this about your very question:

I did a training two weeks ago and all 12 people said "No" when I asked "are database transactions mandatory?". We have a long way...

Do We Always Need A Transaction?

   package com.examscam.model;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
 
@Entity
public class User {
  private Long id;
  private String password;
 
  @Id
  @GeneratedValue
  public Long getId() {return id;}
  public void setId(Long id) {this.id = id;}
  public String getPassword() {return password;}
  public void setPassword(String password) {
    this.password = password;
  }
  public static void main(String args[]){
    AnnotationConfiguration config = 
                     new AnnotationConfiguration();
    config.addAnnotatedClass(User.class);
    config.configure();
    // new SchemaExport(config).create(true, true);
    SessionFactory factory = 
                  config.buildSessionFactory();
    Session session = factory.getCurrentSession();
[B]    session.beginTransaction();[/B]
    System.out.println("creating user");
    
    User u = new User();
    u.setPassword("abc123");
    session.saveOrUpdate(u);
    System.out.println("user saved");
[B]    session.getTransaction().commit();[/B]
    System.out.println("transaction successful!!!");  
  }
}
 

Tutorial: How to Save Data to the Database Using Hibernate and JPA

-Cameron McKenzie