CODEWITHSUNDEEP
javajpaorm
abc
abc

Reputation: 2381

JPA ORM are relations efficient?

I have some doubts on that how for instance @OneToMany might be efficient. Let's assume object A have collections of B objects inside of it and that collection have 100k objects

class A {
    List<B> b; //.size() == 100.000
    ...
}

Even I mark b to being fetch LAZY what would following pseudo-code do?

select from database object into A a;
a.b.add(new B());

If I'm correct, because I made an access to field it has to be loaded, yes? So just to make one insert I have downloaded 100k rows from DB?

Can anyone clarify my doubts?

Upvotes: 0

Views: 33

Answers (1)

V G
V G

Reputation: 19002

Yes, you are right: all 100k rows will be loaded.

What to do?

I suppose that there is also a reverse relationship from B to A. In this case, to avoid the performance problem you persist the B instance, when A has his list of B not loaded. Alternatively you could make a native query.

Upvotes: 1

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