I have an undiretional OneToMany relationship parent owned with cascade.
I would like to know if there is a way to optimize the request the ORM is doing when inserting, updating or deleting. I know how to configure batching, but I see other way of improvement, many requests the ORM is doing could be done in a single query.
By example, consider the following action entityManager.persist(parent) :
0 ms|statement|insert into parent (value) values (1)
0 ms|statement|insert into child (value) values (1)
0 ms|statement|insert into child (value) values (1)
3 ms|statement|insert into child (value) values (1)
0 ms|statement|update child set parent_id=1 where id=1
0 ms|statement|update child set parent_id=1 where id=2
0 ms|statement|update child set parent_id=1 where id=3
Could be replaced by (at least for mysql dialect) :
insert into parent (value) values (1);
insert into child (value) values (1),(1),(1);
update child set parent_id=1 where id in (1, 2, 3);
The cascade delete suffer from the same problem and is optimizable.
How is it possible that hibernate doesn't detect such optimizations ? Do we have a way to hook somewhere in the ORM to filter/improve/replace the queries at runtime ?
Here are the Parent / Child class but I don't think it will help :
@Entity
public class Parent {
@Id @GeneratedValue(strategy = GenerationType.IDENTITY)
public Long id;
public int value;
@OneToMany(cascade = CascadeType.ALL)
@JoinColumn(name = "parentId", referencedColumnName = "id")
public List<Child> children;
public Parent(Long id, int value, List<Child> children) {
this.id = id;
this.value = value;
this.children = children;
}
private Parent() {
}
}
@Entity
public class Child {
@Id @GeneratedValue(strategy = GenerationType.IDENTITY)
Long id;
int value;
public Child(Long id, int value) {
this.id = id;
this.value = value;
}
private Child() {
}
}
