How to open StatelessSession using HibernateCallback?

shagufta · **Joined:** Fri May 22, 2009 4:50 am **Posts:** 59

Hi all,

I am using Spring, Hibernate 3.3.1.GA and PostgreSQL 8.3.7 in my application.

I want to insert many records into a table under heavy load with optimal performance. For that i have decided to use StatelessSession.

I am using HibernateTemplate in all my DAOs but I guess there is no support for StatelessSession inside the hibernateTemplate. But I read in some other forum that HibernateCallback one can get a hold of the native session, get its connection and based on that open a stateless session. But I am very clear on how to do this.

Any help?

Thanks.

mumbaimuru · **Posted:** Mon Sep 21, 2009 10:30 am

Just get the SessionFactory from the Hibernate Session passed to the HibernateCallback and from there create the StatelessSession.

Code:

getHibernateTemplate().execute(new HibernateCallback() {

           public Object doInHibernate(Session session) throws
HibernateException, SQLException {
               StatelessSession statelessSession =
session.getSessionFactory().openStatelessSession();

               ScrollableResults customers = statelessSession
.getNamedQuery("GetCustomers").scroll(ScrollMode.FORWARD_ONLY);
               while ( customers.next() ) {
                   Customer customer = (Customer) customers.get(0);
                   customer.updateStuff(...);
                   statelessSession.update(customer);
               }
               return null;
           }
       });

shagufta · **Joined:** Fri May 22, 2009 4:50 am **Posts:** 59

Thanks Murugesan!

I have one more problem now using stateless session.

I am trying to save my object Quote in database. whcih is as follows:

Code:

Class Quote{
    String source;
    SortedMap bids = new TreeMap();
}

and mapping file for quote is as follows:

Code:

<class name="Quote" table="QUOTE">
      <id name="id" column="QUOTE_ID">
         <generator class="sequence">
            <param name="sequence">seq1</param>
         </generator>
      </id>      
      <property name="source" column="source"/>
      <map name="bids" table="BIDS" sort="natural">
                <key column="quote_id"/>
                 <index column="price"/>   
         <property name="type"/>
               </map>           
</class>   

Now problem is when I am saving my quote, its inserting values only in quote table, QUOTES and no values are inserted in table for map i.e. BIDS.
Any idea why?

Please give me your inputs.

Thanks.

mumbaimuru · **Posted:** Wed Sep 23, 2009 11:42 pm

Pls post your java code which save Quote and etc.

pasha · **Joined:** Sat Nov 27, 2004 4:13 am **Posts:** 137

I don't see any benefit when using stateless session when having INSERT queries,
it has any benefit, I'm not sure!

Stateless Session does not hold references to persisted objects, that's all, if you want to persist the same instance object with different values that's fine, but I'm not sure where it is a good practice or not.

shagufta · **Joined:** Fri May 22, 2009 4:50 am **Posts:** 59

Hi Pasha,

Thanks for your reply.

I have a requirement of inserting high rate incoming data into database.

So using stateless session would not fall over with an OutOfMemoryException. It also confirms from the below thread posted by someone.

viewtopic.php?f=1&t=965733&start=0

So any solution to my problem now??

Any input is valuable.

Thanks.

shagufta · **Joined:** Fri May 22, 2009 4:50 am **Posts:** 59

Oh thanks Murugesan for your reply!

I should hav eposted that in 1st place but never mind. the code is as below:

Code:

void writeQuote(Quote quote) {
      StatelessSession session = sessionFactory.openStatelessSession();
      Transaction tx = session.beginTransaction();      
      session.insert(quote);      
      tx.commit();
      session.close();   
    }

I tried inserting below in the same transaction after inserting the quote just to check but it doesn't work either.

Code:

session.insert(quote.getBidEntries)

Any idea??

Thanks.

mumbaimuru · **Posted:** Thu Sep 24, 2009 5:14 am

Try to print show_sql in console and have a look.

shagufta · **Joined:** Fri May 22, 2009 4:50 am **Posts:** 59

Hi,

Thanks for your reply. I googled more about persisting collections when using stateless sessions.
reason for above behavior is:

Quote:

A stateless session does not implement a first-level cache nor interact with any second-level cache, nor does it implement transactional write-behind or automatic dirty checking, nor do operations cascade to associated instances. Collections are ignored by a stateless session. Operations performed via a stateless session bypass Hibernate's event model and interceptors

Is there any work around to do this?

Any idea?

Thanks.

shagufta · **Joined:** Fri May 22, 2009 4:50 am **Posts:** 59

I wish there was more on stateless session in "Hibernate in Action"..