Hibernate Unable to Start On Large-Scale Database

Question

Hello,

I have been using Hibernate + HSQLDB on my desktop for developing a database adapter for my application. For legacy reasons, the IDs are generated by the application as strings. All was working fine then.

Now, we have a pre-prod database, with a bit more than a million records. I had to do some changes (e.g. identifier too long) on the Hibernate side, but nothing major.

That is, until I got to this problem. When I try to start my application on the pre-prod server, Hibernate starts making a gazillion queries, which eventually end up in a OutOfMemoryError: Java heap space. Increasing the heap max is not helping.

I have disabled C3PO cache settings and disabled hibernate.hbm2ddl.auto. I don't know why it is making these queries, and I don't know how to disable them.

Can anyone help me??????

Answer 1

You told Hibernate to fetch eagerly. So when you load the first object, Hibernate starts to fetch all related objects, too.

You must set all unnecessary relations to fetch=LAZY.