Saving all collection of objects with one command?

olobolo · **Joined:** Mon Feb 13, 2006 8:34 pm **Posts:** 27

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Hibernate version:3.0

Is this possible to save all collection of objects using one command (does something like "saveAll" exits for hibernate) or it is necessary to make it by using save() in a e.g. for loop?

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

There is limited support for bulk operations in HQL. See section 13.4. "DML-style operations" of the ref docs.

You can also write your own bulk-updating code, which would save each object and flush the transaction after all the saves are called. Read all of chapter 13 for more suggestions.

rose · **Joined:** Thu Apr 06, 2006 4:04 pm **Posts:** 9

I am getting the same problem? I went through chapter 13 but this didn't answer my question. How can I save or update a Collection in the database. Can I just use saveOrupdate(Collection)??Please Help.

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

No, you can't do that. You can save each item individually (optimizing the process through judicious use of Session.flush), possibly using stateless sessions. If you can do the updates via a simple SQL statement (e.g. "update table set value = value + 1 where parentid = :parentid") then you can use DML-style updates:

Code:

String hqlUpdate = "update Table t set t.value = t.value + 1 where t.parent = :parent";
Query qry = session.createQuery( hqlUpdate );
qry.setParameter( "parent", parent);
qry.executeUpdate();

This is described in section 13.

Principal Skinner · **Joined:** Mon May 02, 2005 6:17 pm **Posts:** 41

It's not very hard to implement such a mechanism. It's even listed in reference manual.
Here is my implementation

Code:

protected void saveAll(List data)
   {
      Session session = null;
      
      try
      {
         session = getSession();
         for(int i=0;i<data.size();i++)
         {
            Object object = data.get(i);
            session.save(object);
            if(i != 0 && i % BATCH_SIZE == 0)
               session.flush();

         }
         
         session.flush();
      } 
      catch (Throwable e)
      {
         throw new RuntimeException(e.getMessage(),e);
      }
      finally
      {
         if(session != null)
            releaseSession(session);
      }
   }

Session if flushed on every BATCH_SIZE-th element so there is no risk of out of memory error.

rose · **Joined:** Thu Apr 06, 2006 4:04 pm **Posts:** 9

yes it is possible to use a single command. and it is working for me.

public void setXXX(Set set) {
Transaction tx = session.beginTransaction();
Iterator iterator = set.iterator();
while (iterator.hasNext())
{
XXX rec= (XXX)iterator.next();
session.saveOrUpdate(rec);
}
tx.commit();
}

Set of given records are saved here.

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

That's not a single command: you're still calling saveOrUpdate once per item in the colleciton. This is essentially a less-refined version of Skinner's earlier suggestion, though at least your version doesn't have the must-be-avoided "catch Throwable".