OK, on each and every query you can specific a fetching strategy for each child. With that in mind, there are a few fetching strategies and know what they are and how they work go a long way in determining how performant you application will be in that area.
Using the example of
1 parent has 10 children each of which have 10 childred
Fetching Strategies
Lazy - you have to loop through the children to load them. This will give you the N+1 issue, which means the example will require 1+(10*10) or 101 select statements to the database.
Subselect - will use the first query as a subquery to the next level so in the example will create 1+(1*10) pr 11 total select statements. But each subselect would only run when you touch a children collection.
Eager - Would get all in one query, so to speak. Going deeper in children get a little tricky. But also note that you can only set one child collection to eager so if you had a Parent that has two collections, only one of the collections can be eager loaded. because Hibernate will use a left outer join.
Hope that helps clarify things a bit. I highly recommend getting
Java Persistence with Hibernate book which explains things a bit better. Or the online Hibernate documentation.
Good Luck
Mark
