Optimization problem

hhuugguueess · **Joined:** Tue Aug 02, 2005 10:50 am **Posts:** 6

Hi everyone,

I'm a new user of Hibernate and I have a strange problem :

I've 2 classes : Customer AND Story which look like :

Code:

public class Customer {
  private long id;
  private String number;
  private List historique = new ArrayList();

  public Customer() {
  }

  public void setId(long newId) {
     id=newId;
  }
      
  public long getId() {
     return id;
  }

   public void setNumber(String newNumber) {
      this.number=newNumber;
   }
      
   public String getNum_prospect() {
      return this.num_prospect;    
   }
}

Code:

public class Story {
  private long id;
  private Calendar dateHisto;
  private Customer customer;

  public Story() {   
  }
   
  public void setId(long newId) {
     id=newId;
  }
      
  public long getId() {
     return id;
  }
      
  public void setDateHisto(Calendar newDateHisto) {
    if (newDateHisto!=null)
       this.dateHisto=newDateHisto;
  }
   
  public Calendar getDateHisto() {
     return this.dateHisto;
  }
   
  public void setCustomer(Customer newCustomer) {
     this.customer=newCustomer;
  }
   
  public Customer getCustomer() {
     return this.customer;
  }      
}

And the corresponding mapping file looks like :

Code:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
   "-//Hibernate/Hibernate Mapping DTD 3.0//EN" 
   "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.abw.beans">
<class name="com.abw.beans.Customer" table="PROSPECT" lazy="true">
  <id name="id" column="ID_PROSPECT">
     <generator class="increment" />
  </id>
   <property name="number" column="NUM_PROSPECT" />
  <bag name="story" lazy="true" cascade="all" order-by="DATE_HISTO">
   <key column="id_prospect"/>
   <one-to-many class="Historique"/>
  </bag>
</class>
</hibernate-mapping>

Code:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
   "-//Hibernate/Hibernate Mapping DTD 3.0//EN" 
   "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.abw.beans">
   <class name="com.abw.beans.Story" table="HISTORIQUE" lazy="true">
  <id name="id" column="ID_HISTORIQUE">
    <generator class="increment" />
  </id>
  <property name="dateHisto" column="DATE_HISTO" />
  <many-to-one name="customer" column="id_prospect" not-null="true"/>
</class>
</hibernate-mapping>

And my problem is :
When i make a simple request like :

Code:

public Vector getCustomer(int max_result,int deb_result) {
  Session session = HibernateUtil.currentSession();
  Transaction tx = session.beginTransaction();
  Query q = session.createQuery("select customer from Customer");
  q.setMaxResults(max_result);
  q.setFirstResult(deb_result);
  List result = q.list();
  //tx.commit();
  Vector v = new Vector(result.size());
  v.addAll(result);
  return v;
}

AND no reference (at all !!!) to the class Story

When I see the SQL log I can see query like :
select ... from Customer where ...
select ... from Story where ...
select ... from Story where ...
select ... from Story where ...
select ... from Story where ...
...

So my question/problem is :
WHY hibernate make request to the Story objet ???
I have set lazy to true and NO reference to the object !!!

I have read a lot of documentation and I have found no answer.
So please help me !!!!

nico.ben · **Posted:** Wed Aug 03, 2005 8:16 am

Hi !!

try to use cascade="none" in:

Code:

<hibernate-mapping package="com.abw.beans">
   <class name="com.abw.beans.Story" table="HISTORIQUE" lazy="true">
  <id name="id" column="ID_HISTORIQUE">
    <generator class="increment" />
  </id>
  <property name="dateHisto" column="DATE_HISTO" />
  <many-to-one name="customer" column="id_prospect" cascade="none" not-null="true"/>
</class>
</hibernate-mapping>

bye,
nicola

pksiv · **Posted:** Wed Aug 03, 2005 8:59 am

I realize you were probably trying to simplify things, but there are some issues with the code you pasted and it won't actually work.

Customer has the following getter method but no field - I assume this is number.

Code:

public String getNum_prospect() { return this.num_prospect; }

Customer has a field

Code:

private List historique = new ArrayList();

but no getter/setter and the mapped collection is named story.

The story collection is mapped to a Class Historique which I am assuming is Story.

The Query "select customer from Customer" is invalid because customer (lower-case) isn't a mapped object. It should be either "from Customer" or "select customer from Customer customer".

However when I modified it the way I thought it should be, it works as expected without all the extra SELECT statements so I can only assume that my understanding of your code is different than the actual code.