Lazy on an arbitrary join @ManyToOne isn't lazy?

ge0ffrey · **Joined:** Thu Oct 13, 2005 4:19 am **Posts:** 98

I have an entity A which has an arbitrary join (for read-only report HQL purposes only) to an entity B, based on the condition that the B (if it exists) has 3 properties in common.
Note that it's not possible to extract those 3 properties as a separate entity in my domain model because in A they are nullable and in B they are definitely not nullable.

Code:

@ManyToOne(targetEntity = BImpl.class, fetch = FetchType.LAZY)
    @JoinColumns({
        @JoinColumn(name = "prop1_id", referencedColumnName = "prop1_id",
                insertable = false, updatable = false),
        @JoinColumn(name = "prop2_id", referencedColumnName = "prop2_id",
                insertable = false, updatable = false),
        @JoinColumn(name = "prop3_id", referencedColumnName = "prop3_id",
                insertable = false, updatable = false)
    })
    public B getB()
    {
        return b;
    }

Now when I run my old query's on this entity (which don't care about B), it decided to eager fetch the B's anyway? Which of course yields an n+Q query problem for all those query's.

Code:

2008-06-25 11:49:47 DEBUG: select this_.id as id28_8_, this_.version as version28_8_, ... from a this_ 
2008-06-25 11:49:47 DEBUG: select b0_.id as id29_0_, b0_.version as version29_0_, b0_.prop1_id as prop13_29_0_, b0_.otherProp_id as otherProp_29_0_, ... from b b0_ where b0_.prop1_id=? and ...
2008-06-25 11:49:47 DEBUG: select b0_.id as id29_0_, b0_.version as version29_0_, b0_.prop1_id as prop13_29_0_, b0_.otherProp_id as otherProp_29_0_, ... from b b0_ where b0_.prop1_id=? and ...
...

Is this a known bug or I am missing an magic hibernate specific annotation to fix this surprising behavior?

ge0ffrey · **Joined:** Thu Oct 13, 2005 4:19 am **Posts:** 98

It looks to me as it can't create a B proxy without initializing the id of its B, so it looks up the B id based on the 3 properties.
But in fact, I don't care about that B proxy (the reference can be null for all I care): however the current implementation creates an n + 1 query problem that kills my performance.

ge0ffrey · **Joined:** Thu Oct 13, 2005 4:19 am **Posts:** 98

Is there any way to avoid the n+1 query problem?

ge0ffrey · **Joined:** Thu Oct 13, 2005 4:19 am **Posts:** 98

Would it be possible to avoid this problem by introducing an entity C between A and B which has a lazy by default @OneToOne from A to C, before it references to B from C?