Question

Entity A has two unidirectional & lazy one-to-one relationships to B (i.e. there’s no inverse relationship).

@OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL, optional = false)
@JoinColumn(name = "first_b_id")
private B firstB;

@OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL, optional = false)
@JoinColumn(name = "second_b_id")
private B secondB;

Lazy-loading works fine. BUT if I invoke

myA.getSecondB()

the SQL log shows that Hibernate issues something like

select * from B where id in (value1, value2)

Hence, the relationships are treated lazily but they’re all loaded at once.
What are the explanations and work-arounds for this?

Oh, why is that so relevant you may ask… Well, the B entities are LOBs. One is the 5+MB original, the other is a 200KB “preview”. Of course I only want to load the original if absolutely necessary.

Answer 1

The explanation is probably that you enabled batch fetching for the class B (or for every entity using the hibernate.default_batch_fetch_size configuration property).