Hibernate throws MultipleBagFetchException - cannot simultaneously fetch multiple bags

Question

Hibernate throws this exception during SessionFactory creation:

org.hibernate.loader.MultipleBagFetchException: cannot simultaneously fetch multiple b

Answer 1

To fix it simply take Set in place of List for your nested object.

@OneToMany
Set objectList;

and don't forget to use fetch=FetchType.EAGER

it will work.

There is one more concept CollectionId in Hibernate if you want to stick with list only.

But remind that you won't eliminate the underlaying Cartesian Product as described by Vlad Mihalcea in his answer!