CrudRepository and Hibernate: save(List) vs save(Entity) in transaction

Answer 1

From SimpleJpaRepository:

@Transactional
public  List More save(Iterable entities) {

    List result = new ArrayList();

    if (entities == null) {
        return result;
    }

    for (S entity : entities) {
        result.add(save(entity));
    }

    return result;
}

So, your second business method only shadows save(Iterable entities) Crud Repository method, in the sense that it iterates the list and calls save(S) on your behalf.

As long as transaction is demarcated from your processData business method, there is no really a difference in performance or queries executed.