在@OneToMany中使用Hibernate 4.2的性能 - 單向vs雙向

Question

我只需要一個單向關係OneToMany，但是在性能方面我想問一下什麼是最佳實踐？

我沒有使用JUnit測試，並具有雙向結果是：1.9s和單向代碼2.4S，似乎單向需要更多的時間

我使用Hibernate的4.2.21

@Unidirectional 2.4S

Parent.class

@OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL) 
@JoinColumn(name = "parentuni_id") 
private Set<ChildUni> childs; 

Hibernate: select nextval ('parentuni_seq') 
Hibernate: select nextval ('childuni_seq') 
Hibernate: select nextval ('childuni_seq') 
Hibernate: insert into parentuni (parentuni_name, parentuni_id) values (?, ?) 
Hibernate: insert into childuni (childuni_name, childuni_id) values (?, ?) 
Hibernate: insert into childuni (childuni_name, childuni_id) values (?, ?) 
Hibernate: update childuni set parentuni_id=? where childuni_id=? 
Hibernate: update childuni set parentuni_id=? where childuni_id=? 

@Bidirectional 1.9s

Parent.class

@OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, mappedBy = "parent") 
private Set<Child> childs; 

Child.class

@ManyToOne(fetch = FetchType.LAZY) 
@JoinColumn(name = "parent_id", nullable = false) 
private Parent parent; 

Hibernate: select nextval ('parent_seq') 
Hibernate: select nextval ('child_seq') 
Hibernate: select nextval ('child_seq') 
Hibernate: insert into parent (parent_name, parent_id) values (?, ?) 
Hibernate: insert into Child (child_name, parent_id, child_id) values (?, ?, ?) 
Hibernate: insert into Child (child_name, parent_id, child_id) values (?, ?, ?) 

Answer 1

在Hibernate best practices，它說

體型雙向關聯：

• 單向關聯更難以查詢。在大型應用程序中，幾乎所有的關聯都必須在查詢中雙向導航。

有用來源：http://www.javacodegeeks.com/2011/02/hibernate-mapped-collections.html

希望這有助於。