Hibernate在保存级联时加入联接

Question

Let´s say I have an entity A that has a relationship oneToMany with B with cascade ALL type and by default lazy. My question now is, what happend, if now I modify A, but B keep in session exactly the same, and I save A. Hibernate will do the join with B and he will update on database, or he will keep B as hibernate proxy?.

We´re facing some problems on our application, since MySQL is complaining for the maximum number of joins when we save the top level entity.

  ERROR 1116 (HY000): Too many tables; MySQL can only use 61 tablesin a join

Regards.

Answer 1

I had a similar problem, but with eager fetched relationships. Once we changed them to lazy, the problem was gone.

Hibernate shouldn't make joins with other lazy-related tables when updating only table A in your example, but best is to print out the generated SQL and see if and how it changes when you change your fetch settings.