Hi,
I assume I am having the N+1 select problem.
I got this entity:
Code:
@Entity
@Table(name = "Devices")
public class Device implements Serializable {
@OneToOne(mappedBy="holdingDevice", fetch=FetchType.LAZY)
@Cascade(CascadeType.ALL)
private WarrantyEntry warranty;
@OneToOne(fetch=FetchType.LAZY)
@JoinColumn(name = "tradeInOldDevice")
@Cascade(CascadeType.ALL)
private Device tradeInOldDevice;
@OneToOne(mappedBy="tradeInOldDevice", fetch=FetchType.LAZY)
private Device tradeInNewDevice;
..
}
This is the other entity:
Code:
@Entity
@Table(name = "Warranty")
public class WarrantyEntry implements Serializable{
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private Long id;
@OneToOne
@JoinColumn(name = "serial")
private Device holdingDevice;
Now when I am starting to iterate over this loop:
Set<Device> customerDevices = user.getCustomer().getDevices();
for (Device device : customerDevices) {
...
}
I am stuck and I see in the log that Hibernate selects:
Hibernate: */ select warrantyen0_.id as...
Hibernate: /* load myclass.Device */
Hibernate: */ select warrantyen0_.id as ..
Hibernate: /* load myclass.Device */...
Over and over I guess I am having the n+1 select problem.
To try fix this I tried to use fetching this way:
Code:
Set<Device> customerDevices = user.getCustomer().getDevices();
String query="from Customer c left join fetch c.devices d \n" +
"left join fetch d.tradeInOldDevice " +
"left join fetch d.tradeInNewDevice "+
"left join fetch d.warranty";
deviceDao.getSessionFactory().openSession().createQuery(query);
for (Device device : customerDevices) {
...
}
Any idea why It still didnt fetch right?
Thanks,
ray.
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