When should one avoid using NHibernate's lazy-loading feature?

Question

Most of what I hear about NHibernate\'s lazy-loading, is that it\'s better to use it, than not to use it. It seems like it just makes sense to minimize database access, in

Answer 1

The usual tradeoff for lazy loading is that you make a smaller hit on the database up front, but you end up making more hits on it long-term. Without lazy loading, you'll grab an entire object graph up front, sucking down a large chunk of data at once. This could, potentially, cause lag in your UI, and so it is often discouraged. However, if you have a common object graph (not just single object - otherwise it wouldn't matter!) that you know will be accessed frequently, and top to bottom, then it makes sense to pull it down at once.

As an example, if you're doing an order management system, you probably won't pull down all the lines of every order, or all the customer information, on a summary screen. Lazy loading prevents this from happening.

I can't think of a good example for not using it offhand, but I'm sure there are cases where you'd want to do a big load of an object graph, say, on application initialization, in order to avoid lags in processing further down the line.