Problem in generating the Primary Key using a Sequence

[Amit Chauhan]

Hi All ,
I am trying to persist an object and also generating the primary key using a default sequence . But the problem is that the Primary key is getting incremented by 2 instead of 1 . My code looks like this :
----------------------------------------------------------------------------------------------------------------------------

   
import java.util.HashMap;
 
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
import javax.persistence.PersistenceContext;
import javax.persistence.PersistenceContextType;
import javax.persistence.PersistenceUnit;
 

public class entityCaller {
 

// @PersistenceContext(unitName="testApp" ,type=PersistenceContextType.EXTENDED)
EntityManager em;
 
// @PersistenceUnit(unitName="testApp")
EntityManagerFactory emf ;
 

public void persistEntity( String Name , int Age ) {
 
EntityManagerFactory emf =
Persistence.createEntityManagerFactory("testApp", new HashMap());
em = emf.createEntityManager();
 
EntityTransaction entityTransaction = em.getTransaction();
 
Tab1 oBJTab1 = new Tab1();
// oBJTab1.setId(Age);
oBJTab1.setVal(Name);
 
try{
 
System.out.println("Making object");
 
em.persist(oBJTab1);
 
System.out.println("Done");
 
System.out.println("Making object2");
System.out.println("Entered the Values");
}catch (Exception e) {
e.printStackTrace();
}finally{
em.close();
}
 

}
public static void main(String[] args) {
entityCaller caller = new entityCaller();
caller.persistEntity("DoAgain7",2);
}
 

}
 
 

--------------------------------------------------------------------------------------------------------------------------

My persistence.xml looks like this :
 

 
<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.0" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence <a href="http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">" target="_blank" rel="nofollow">http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"></a>
<persistence-unit name="testApp">
<provider>oracle.toplink.essentials.ejb.cmp3.EntityManagerFactoryProvider</provider>
<class>Tab1</class>
<!-- <jta-data-source>java:/XAOracleDS</jta-data-source> -->
<properties>
<!-- Provider-specific connection properties -->
<property name="toplink.jdbc.driver" value="oracle.jdbc.driver.OracleDriver"/>
<property name="toplink.jdbc.url" value="jdbc :-o	 racle:thin:@127.0.0.1:1521:XE"/>
<property name="toplink.jdbc.user" value="system"/>
<property name="toplink.jdbc.password" value="jlkklkj"/>
<!-- Provider-specific settings -->
 
<!-- other values are: drop-and-create-tables|none -->
</properties>
</persistence-unit>
</persistence>
---------------------------------------------------------------------------------------------------------------------------
 

Please provide me with some pointer as to know where the things are going wrong.

[Mark Spritzler]

What is your class mapping look like. When you say the default sequence, do you mean something like "hibernate_seq" and then therefore more than one object is mapped to generating the PK from that sequence table, such that I insert one record in table A it gets id 1, then insert one record into table B it gets id 2, then insert again into table A and it gets id 3?

Or do you have it mapped for objects A mapped to Table A and Sequence "a_seq" and for Object B mapped to Table B and sequence "b_seq"

Mark

[Erik Bengtson]

A sequence in JPA maps to a database sequence. You should check your DB first.

select <seqname>.NEXTVAL FROM DUAL

if it gets incremented by 1, then check your code, later report a bug to the jpa vendor

[Amit Chauhan]

Hi ,
By default sequence I mean that I have not created it using sql at the database rather I am creating it directly while code .

Here is the entity bean code :

  import java.io.Serializable;
 
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.SequenceGenerator;
 
@Entity
public class Tab1 implements Serializable {
@Id
@GeneratedValue(generator="SeqGenerator")
    @SequenceGenerator(name="SeqGenerator", allocationSize=1)
private int id;
 
private String val;
 
private static final long serialVersionUID = 1L;
 
public Tab1() {
 System.out.println("Thread Name"+Thread.currentThread().getName());
  System.out.println("Inside Constructor of Tab1");
}
 
public int getId() {
return this.id;
}
 
public void setId(int id) {
this.id = id;
}
 
public String getVal() {
return this.val;
}
 
public void setVal(String val) {
this.val = val;
}
 
}
  

*******The most strange thing is that I find the value of sequence being incremented by 2 and not by 1 .


Kindly help me out .