In my application, there is a confused problem. There are two tables (A,B). Association like one-to-one, many-to-one is exist. But in application, some query need infomation from two tables and the other only need infomation of table A. If I config the association in hbm and java class, hibernate will select two tables all columns for me. But sometime I only need little column. My question is how to improve performance? I want hibernate select columns I need, at least, not to select columns of table B when I don't need infomation from table B. Now I config two hbm to one table. Is it a good way to solve my problem? Or is there any better way, pattern exist?
By the way, I don't understant "Three different O/R mapping strategies" well. May somebody explain it detail?
http://www.hibernate.org/4.html#A18

Use lazy="true" for your associations. Then use join fetch in HQL to override lazy loading behaviour.