I'm evaluating hibernate and trying to figure out is it suitable for me or not. I've tried to execute "select bean from table_name as bean" query using session.createQuery() and session.find() methods and i've found that createQuery() method executes 1 select for all PKs and then N selects to pupulate beans but find() method calls DB only one time for the same query. What's is the difference?

session.iterate() and query.iterate() do the N+1 stuff
session.find() and query.list() do 1 request

the find stuff won't look at the cache
the iterate stuff load the pks and lokk at the cache for each asked object before lokking to in the db.

Have a look at the javadoc and the reference guide for more info.

Does find() method update the cache with the loaded objects? and what could be a reason to use session.iterate() due to N+1 problem?

yes.




if you expect the objects to be in the cache