Data is not inserting without transaction commit option!!!

sprateek · **Posted:** Mon Jan 18, 2010 11:35 am

Hello All,

I created a simple hibernate project where I am inserting a row into database table. But it insert the data only when I use org.hibernate.Transaction commit. If I dont use transaction commit It neither insert any thing in to database nor show any error on console.

My hibernate config file is

Code:

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
          "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
          "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<!-- Generated by MyEclipse Hibernate Tools.                   -->
<hibernate-configuration>

<session-factory>
   <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
   <property name="connection.url">
      jdbc:mysql://localhost:3306/chat?autoReconnect=true
   </property>
   <property name="connection.username">root</property>
   <property name="connection.password">root</property>
   <property name="connection.driver_class">
      com.mysql.jdbc.Driver
   </property>
    <property name="hibernate.hbm2ddl.auto">update</property>
   <property name="format_sql">true</property>
   <property name="hibernate.connection.pool_size">10</property>
   
      <property name="show_sql">true</property>
      
   <!-- <property name="myeclipse.connection.profile"></property> -->
   <mapping resource="code/contact.hbm.xml" />
</session-factory>

</hibernate-configuration>

My code is

Code:

package code;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;



/**
 * @author Deepak Kumar
 *
 * http://www.roseindia.net
 * Hibernate example to inset data into Contact table
 */
public class FirstExample {
  public static void main(String[] args) {
    Session session = null;
    org.hibernate.Transaction tx = null;
    
    try{
      // This step will read hibernate.cfg.xml 


      SessionFactory sessionFactory = new 

Configuration().configure().buildSessionFactory();
       session =sessionFactory.openSession();
        //Create new instance of Contact and set 
       tx =  session.beginTransaction();

         System.out.println("Inserting Record");
        Contact contact = new Contact();
        //contact.setId(67);
        contact.setFirstname("Deepak");
        contact.setLastname("Kumar");
        contact.setEmail("deepak_38@yahoo.com");
        
        session.save(contact);
        System.out.println(contact.getId());
        System.out.println("Done");
        
    }catch(Exception e){
      System.out.println(e.getMessage());
    }finally{
      // Actual contact insertion will happen at this step
       tx.commit();
       session.flush();
        session.close();

      }
    
  }
}

Please tell me what may be the reason.

Regards,
Prateek

kossmo · **Joined:** Thu Dec 10, 2009 10:53 am **Posts:** 50

Hello Prateek,

that's exptected afaik. If you do not commit your transaction it won't be written to the database. This is how databases handle reading and writing from it. Your code is fine but you should probably call Transaction.rollback() if the transaction did not succeed, like so:

Code:

           
            t.commit();
        } catch (Exception e) {
            e.printStackTrace();
            if (t != null) {
                t.rollback();
            }
        }

pb00067 · **Joined:** Tue Jun 16, 2009 3:36 am **Posts:** 990

This is due to the so called write-behind mechanism of hibernate, which performs DML-statements as latest as possible.
If you want force the DML-statements to be executed before the commit, then you can call flush explicitly.

aithal.chandra · **Joined:** Fri Mar 12, 2010 6:22 am **Posts:** 1

Hi,
I also have taken the same sample program. As per the specification, by flushing a Session at the end of a unit of work, to execute the SQL DML operations (UPDATE, INSERT, DELETE) that synchronize the in-memory Session state with the database.
In that case, by using session.flush() should insert a record in the database. I am not sure why we need to open the Transaction API for the commit
Can someone help me out to understand this

pb00067 · **Joined:** Tue Jun 16, 2009 3:36 am **Posts:** 990

Quote:

I am not sure why we need to open the Transaction API for the commit
Can someone help me out to understand this

The flush operation is not the same as commit as it does not terminate the transaction!
Each transaction must be terminated either by commit or a rollback call.
If you never call commit or rollback then sooner or later (it depends on your db-config)
your transaction with go in timeout and your database will rollback the transaction implicitly.
Only with the commit call the updated/changed data gets definitely consolidated on the db.
Furthermore with ReadCommited isolation level (or higher) the commit call is also the moment where
the changed data gets visible to other transactions.

kochcp · **Posted:** Fri Mar 12, 2010 9:12 am

that's just how java Transactions are specified. You can change the Transaction to auto-commit, by default it is disabled.