Hibernate - how to delete with condition without loading to memory?

Question

I have an object -

 @Entity
 public class myObject{
      public string fieldA;
      public string fieldB
      ...
 }

I don't have any instance of it but I want to delete all the rows in db that have fieldA == A.

Is this the correct way ?

    try {
        session.beginTransaction();
        session.createQuery("delete from MyObject where fieldA = " +        
                             "BlaBla").executeUpdate();

        session.getTransaction().commit();
        savedSuccessfully = true;
    } catch (HibernateException e) {
        session.getTransaction().rollback();
        savedSuccessfully = false;

    } finally {
        session.close();
    }
    return savedSuccessfully;

Michael J. Lee · Accepted Answer · 2011-07-06 17:13:11Z

2

Take a look at using native sql in hibernate and the session.createSQLQuery to make sure hibernate doesn't get involved with wiring beans with HSQL.

Also avoid using String concatenation to build your queries. Lastly, your database will most like be your bottle neck with a simple query like this so make sure you have proper indexes on the table.

edited Jul 6, 2011 at 17:13

answered Jul 6, 2011 at 17:07

Michael J. Lee

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Comments

Lawrence McAlpin · Accepted Answer · 2011-07-06 19:04:39Z

0

Yes, to do a batch delete without first having to query the data, you would use HQL:

session.createQuery("delete from MyClass where ...").executeUpdate();

answered Jul 6, 2011 at 19:04

Lawrence McAlpin

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Comments

user591593 · Accepted Answer · 2011-07-08 07:29:17Z

0

why would you do that if you have decided to implement using ORM ?

The correct procedure to delete something under ORM implemented application would be:

get the object with the related fieldA and fieldB
delete the object

answered Jul 8, 2011 at 7:29

user591593

1 Comment

Michael Piefel Over a year ago

Because it’s inefficient to load something from the DB into memory just to delete it. Sometimes that does not matter much, sometimes it makes all the difference.

Gordian Yuan · Accepted Answer · 2011-07-08 07:30:03Z

0

To execute an HQL DELETE, use the Query.executeUpdate() method

See Batch processing

answered Jul 8, 2011 at 7:30

Gordian Yuan

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