The class A owns a set of B as the below codes

class A
{
Set b;

Set getB() { return b; }
}

class B
{
int flag;

int getFlag() { return flag; }
}

The mapping file of class B is below

<hibernate-mapping>
<class name="B" table="b" where="flag > 0">
....

I exludes some instances of B by the where clause. But the relation between A and B is mapped to a join table and the the relation is loaded when a instance of A is initiated.

If a instance of B is referencd by a instance of A and the instance is exluded by where clause, a exception is throwed when the B's instance is reached through A's instance.