Stop automatic persist of parents children?

[pieterjan]

Hi,

I came upon this problem when looking at the hibernate queries that JBoss AS executes for bi-directional relations (i.e. parent-child).

The problem is that when a method of a session bean is called and in that method a parent entity bean is used, then after finishing the method the server will execute a ton of select statements for the children.
My guess, to merge or update the children.

But seeing as I only access properties, I would like a way to stop this automatic update of the children.

If anyone knows a way, I'm all ears.


The annotations for parent and children I use now look as follows:

// in the parent entity bean

 @OneToMany(targetEntity=ChildBean.class,
 mappedBy="parent",
 cascade=CascadeType.ALL,
 fetch=FetchType.LAZY)
 private List<ChildBean> children;


// int the child entity bean

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

[pieterjan]

Interesting.

I found the following link http://e-docs.bea.com/workshop/docs81/doc/en/core/index.html at the bea website.
Where in the section 'Developing Enterprise JavaBean' > 'Developing Entity Beans' > 'Accelerating Entity Bean Data Access' they give a few pointers on how to make entity beans that are read only.

I wonder if I could do the same in JBoss and if this would prevent the server from trying to update each entity bean?

[pieterjan]

I found out that the simple parent-child example I gave, does not produce the selection statements I was talking about. Instead a parent-child-grandchild relation does produce the problem.


I used the following classes to test (the getters and setters are removed here) :

// Parent

@Entity(access = AccessType.FIELD)
@Table(name="t_tests", schema="grid")
@SequenceGenerator(name="TestBeanSequence", sequenceName="grid.s_tests")
public class TestBean implements Serializable {

 @Id(generate=GeneratorType.SEQUENCE, generator="TestBeanSequence")
 private Integer id;

 @Column(length=255)
 private String someText;

 @Basic(temporalType = TemporalType.TIMESTAMP)
 private Date someDate;

 private Boolean someBoolean;

 @OneToMany(targetEntity=TestChildBean.class,
 mappedBy="test",
 cascade=CascadeType.ALL,
 fetch=FetchType.LAZY)
 private List<TestChildBean> testChildren;
}


// Child

@Entity(access = AccessType.FIELD)
@Table(name="t_testchilds", schema="grid")
@SequenceGenerator(name="TestChildBeanSequence", sequenceName="grid.s_testchilds")
public class TestChildBean {

 @Id(generate=GeneratorType.SEQUENCE, generator="TestChildBeanSequence")
 private Integer id;

 @Column(length=20, nullable=false)
 private String name;

 @ManyToOne(targetEntity=TestBean.class, fetch=FetchType.LAZY)
 @JoinColumn(name="test_id", nullable = false)
 private TestBean test;

 @OneToMany(targetEntity=TestGrandChildBean.class,
 mappedBy="testChild",
 cascade=CascadeType.ALL,
 fetch=FetchType.LAZY)
 private List<TestGrandChildBean> testGrandChildren;
}

// Grandchild

@Entity(access = AccessType.FIELD)
@Table(name="t_testgrandchilds", schema="grid")
@SequenceGenerator(name="TestGrandChildBeanSequence", sequenceName="grid.s_testgrandchilds")
public class TestGrandChildBean {

 @Id(generate=GeneratorType.SEQUENCE, generator="TestGrandChildBeanSequence")
 private Integer id;

 @Column(length=20, nullable=false)
 private String name;

 @ManyToOne(targetEntity=TestChildBean.class, fetch=FetchType.LAZY)
 @JoinColumn(name="testchild_id", nullable = false)
 private TestChildBean testChild;
}

[pieterjan]

Solved it!

Apparently it had nothing to do with read-only beans but with the way JBoss 4.0.2 checks for dirty entity beans.
Upgrading to 4.0.3SP1 solved the problem.

BTW, the performance increase is HUGE.