JPA/Hibernate bulk(batch) insert

Question

Here is simple example I\'ve created after reading several topics about jpa bulk inserts, I have 2 persistent objects User, and Site. One user could have many site, so we ha

Answer 1

I have found it much more efficient to bypass hibernate for bulk inserts. You must do away with ORM (object relational mapping) but you can still leverage the connection associated with the current session and the transaction management.

While you temporarily lose the convenience of your ORM, the payoff is significant, especially if you have natively generated Ids since hibernate would normally perform one SELECT for each INSERT.

Session.doWork is very handy for facilitating this.

private MyParentObject saveMyParentObject(final MyParentObject parent, final List<MyChildObject> children)
{
    transaction = session.beginTransaction();
    try
    {
        session.save(parent); // NOTE: parent.parentId assigned and returned here

        session.doWork(new Work()
        {
            public void execute(Connection con) throws SQLException
            {
                // hand written insert SQL - can't use hibernate
                PreparedStatement st = con.prepareStatement("INSERT INTO my_child (parent_id, name, ...) values (?, ?, ...)");

                for (MyChildObject child : children)
                {
                    MyChildObject child = new MyChildObject();
                    child.setParentId(parent.getParentId()); // assign parent id for foreign key

                    // hibernate can't help, determine jdbc parameters manually
                    st.setLong(1, child.getParentId());
                    st.setString(2, child.getName());
                    ...
                    st.addBatch();
                }

                // NOTE: you may want to limit the size of the batch
                st.executeBatch();
            }
        });

        // if your parent has a OneToMany relationship with child(s), refresh will populate this 
        session.refresh(parent);
        transaction.commit();
        return parent;
    }
    catch(Throwable e)
    {
        transaction.rollback();
        throw new RuntimeException(e);
    }   
}

Answer 2

I have written a short blog which talks about batch insert gotchas and also has pointer to small project that has all the right configurations to get started with batch insert with Hibernate. See the details at http://sensiblerationalization.blogspot.com/2011/03/quick-tip-on-hibernate-batch-operation.html

Answer 3

If you're using the database to generate ids, then Hibernate has to execute a query to generate the primary key for each entity.