I apologize if this is covered somewhere in documentation; I haven't been able to find it.

I have a uni-directional one-to-many relationship defined by a <map>. (The parent knows about the children, but not vice-versa). The problem is that the parent can have so many children that it is not reasonable to load the entire collection of children at once - the application will exceed memory restrictions.

Is it possible to make the contents of this collection load lazily? I'm thinking ideally by batch. My map-key is (essentially) a date (actually it's a custom type that represents a date). What I'd like is that when I do this:

parent.getChild(date);

that Hibernate would load a batch of that parent's children for keys on or around that date.

Is this possible, or do I need to essentially populate the map manually?

Maybe you want to evaluate filters:
http://www.hibernate.org/hib_docs/v3/re ... lters.html

Mike,

Thanks, your answer is helpful, and I think it may solve my problem.

It seems, though, that there ought to be a more seamless way to do what I'm trying to do. Using filters allows me to do something like this:

Parent parent = session.load(...);
session.enableFilter("byDate").setParameter("date", date1);
Child child1 = parent.getChild(date1);
session.enableFilter("byDate").setParameter("date", date2);
Child child2 = parent.getChild(date2);

But ideally I'd like to do the above, without having to set the filter parameters each time I want to retrieve a new child from the parent. (Maybe in the persistence layer I don't know exactly what children I'll need, and when I'm calling parent.getChild(), I'm not in Hibernate-aware code, so it's not convenient to deal with filters.) What would be cool is if every time I call getChild(), Hibernate could anticipate whether it needs to go to the database to retrieve another batch of children.

Oh well, like I said, I think I can do what I need with filters. Thanks for your response.