Does LAZY fetch type produce N +1 select

Question

After reading this article enter link description here

I got the idea that a fetch mode = LAZY will always result in N +1 problem. IS this true? If so ,why? OpenJPA/Hibernate should be able to optimize the query even if fetch type is LAZY. No?

score 0 · Answer 1 · answered Jul 30 '13 at 03:54

0

You can specify eager fetch in query to avoid it. This produces a JOIN sql.

Criteria c = session.createCriteria(Entity1.class);
c.setFetchMode("anotherObj", FetchMode.JOIN)
return c.list();

answered Jul 30 '13 at 03:54

Yugang Zhou

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My question is not how to avoid N +! by an eager fetch, but...does a LAZY fetch automatically mean a N +1 select? – Victor Jul 30 '13 at 14:30

score 0 · Answer 2 · answered Jul 31 '13 at 03:23

Yes, it will. But the extra SELECTs are executed only when you access the objects defined in a relationship (that's why it is called LAZY load).

This is an excellent article that explains it in more details: http://www.mkyong.com/hibernate/hibernate-fetching-strategies-examples/

Cheers

Does LAZY fetch type produce N +1 select

2 Answers2