Hibernate @ManyToOne on non-primary keys of parent entities fetching parent entities too

Question

Facing a strange issue while using @ManyToOne on non-primary keys of parent entities. When i fetch child entity hibernate is fetching parent entity too even though it is asked to fetch that lazily and I didn't query anything from parent entity.

Here is the example entity that I am using

Property Entity is the parent entity which has a column property_id and it is non-primary key.

public class Property extends AbstractEntity implements Serializable {

private static final long serialVersionUID = 8412320472079820864L;

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
Long id;

@Column(name = "property_id")
public Long propertyId;

@NotNull(message = "Name can't be null")
@Size(max = 100)
@Column(name = "name")
public String name;

Now I have a Room entity which is mapped with Property entity via column property_id.

public class Room extends AbstractEntity implements Serializable {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
Long id;

@Column(name = "name")
private String name;

@Column(name = "size")
private String size;

@Column(name = "room_type")
private RoomType roomType = RoomType.STANDARD_ROOM;

@ManyToOne(targetEntity = Property.class, fetch = FetchType.LAZY)
@JoinColumn(name = "property_id", referencedColumnName = "property_id", nullable = false)
private Property property;

@Column(name = "priority")
private Integer priority;

Now when I fetch Room hibernate hits database to fetch property too.

Can someone please explain what is it that I am missing?

I tried implementing interceptor still no luck

@ManyToOne(fetch = FetchType.LAZY,optional = false)
@JoinColumn(name = "property_id", referencedColumnName = "property_id", insertable = false, updatable = false)
@LazyToOne(LazyToOneOption.NO_PROXY)
public Property getProperty() {
    if (interceptor != null) {
        return (Property) interceptor.readObject(this, "property", property);
    }
    return property;
}

public void setProperty(Property property) {
    if (interceptor != null) {
        this.property = (Property)interceptor.writeObject(this, "property", this.property, property);
        return;
    }
    this.property = property;
}

P.s: I tried to use @NaturalId annotation too but it didn't worked.

Not sure if it has anything to do with the problem, but why do you have two keys? Why have both id and property_id in Property? — ewramner, Mar 14 '19 at 07:06
actually we are migrating data from one service to other and we need to preserve that other system's database id so made this, and now this is becoming the bottleneck. — Ekansh Gautam, Mar 14 '19 at 07:33
See this: https://stackoverflow.com/questions/30082281/manytoonefetch-fetchtype-lazy-doesnt-work-on-non-primary-key-referenced-co — , Mar 14 '19 at 07:50
Well, how about migrating the other system's ids into your own id column and make sure that your generated ids start somewhere above them? A long is quite large, so reasonably there should be plenty of room left even if you take the largest used value and add a reasonable margin. Then you can have a clean data model without this exotic mapping. — ewramner, Mar 14 '19 at 08:51

Hibernate @ManyToOne on non-primary keys of parent entities fetching parent entities too

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