JPA and Hibernate : one to one mapping causes three select queries -

jpa 2.0 hibernate 4.3.5

hi,

following onetoone mapping (with example code assuming 1 customer can have 1 order)

class customer {     private order order;     @onetoone(mappedby="customer", fetch=fetchtype.lazy)     public order getorder() { return order; }     public void setorder(order order) { this.order = order ; } }  class order {     private customer customer;     @onetoone(fetch=fetchtype.lazy)     @joincolumn(name="cust_id")     public customer getcustomer() { return customer; }     public void setcustomer(customer customer) { this.customer = customer; } }  //calling code order order = em.find(order.class, 4);    // line 1 system.out.println(order.getcustomer());  // line 2 </code> 

above calling code resulting in 3 select statements i.e

line 1 causing

   select * order id = ?      #1 

line 2 causing following 2 statements

   select * customer id = ?   #2    select * order cust_id = ? #3 

my question: shouldn't 2 queries (i.e #1 , #2) given lazy fetching enabled on both ends ?

thanks, rakesh

you have defined both relationships lazy.

when load order customer attribute not loaded because lazy. lazy attribute loaded when accessed or if define eagerly loaded.

every mapping finished 1 (onetoone or manytoone) eagerly default, set lazy.

try define relationship eager:

@onetoone(fetch=fetchtype.eager) // or @onetoone @joincolumn(name="cust_id") public customer getcustomer() { return customer; } 

by way, customer can have 1 order? o.o