Generated primary keys start form 9951 instead of the 10000

Question

Hello,

I make use of:

NetBeans IDE 6.7.1, GlassFish v2.1, Oracle 10g XE, JAVA 6 SE, JAVA 5 EE,

From inside a stateless EJB I persist entities of type customer I have the annotation: @SequenceGenerator(name="seq", sequenceName="cust_id_seq") in the class customer so the primary keys are autogenerated in the database from the sequence cust_id_seq but when I persist the first customer the primary key is 9951 instead of 10000, the primary key of the second customer is 9952. The output of the GlassFish v2.1 after I persisted two customers is:

Application server startup complete.

My id is: 0

TopLink, version: Oracle TopLink Essentials - 2.1 (Build b31g-fcs (10/19/2009))

Server: unknown file:/C:/Documents%20and%20Settings/IOANNIS_PAPAIOANNOU/My%20Documents/NetBeansProjects/VideoClub/dist/gfdeploy/VideoClub-ejb_jar/-vc_pu login successful

My id is: 9951

My id is: 0

My id is: 9952

@Entity
@Table(name = "customer")
@SequenceGenerator(name="seq", sequenceName="cust_id_seq")
public class Customer implements Serializable
{

@Id
@GeneratedValue(strategy=GenerationType.SEQUENCE, generator="seq")
@Column(name="CUST_ID")
private int id;

@Column(name = "phone_number")
private int phoneNumber;

@Column(name = "first_name")
private String firstName;

@Column(name = "last_name")
private String lastName;

@Column(name = "credit")
private int credit;

@OneToMany    
private Collection<CustRentMovie> rents = new ArrayList<CustRentMovie>();

public int getCredit()
{
    return credit;
}

public void setCredit(int credit)
{
    this.credit = credit;
}

public String getFirstName()
{
    return firstName;
}

public void setFirstName(String firstName)
{
    this.firstName = firstName;
}

public int getId()
{
    return id;
}

public void setId(int id)
{
    this.id = id;
}

public String getLastName()
{
    return lastName;
}

public void setLastName(String lastName)
{
    this.lastName = lastName;
}

public int getPhoneNumber()
{
    return phoneNumber;
}

public void setPhoneNumber(int phoneNumber)
{
    this.phoneNumber = phoneNumber;
}

public Collection<CustRentMovie> getRents()
{
    return rents;
}

public void setRents(Collection<CustRentMovie> rents)
{
    this.rents = rents;
}


}

the code of the EJB:

@Stateless
public class ClerkSessionBean implements ClerkSessionRemote
{

@PersistenceContext(unitName = "vc_pu")
private EntityManager em;

public int writeCustomer(AlmostCustomer almostCustomer)
{

    Customer customer = new Customer();
    System.out.println("My id is: " + customer.getId());
    customer.setFirstName(almostCustomer.getFirstName());
    customer.setLastName(almostCustomer.getLastName());
    customer.setPhoneNumber(almostCustomer.getPhoneNumber());
    em.persist(customer);
    System.out.println("My id is: " + customer.getId());
    return customer.getId();
}
}

part of the script that creates the database:

CREATE table customer
(
cust_id NUMBER(5),
phone_number NUMBER(10) NOT NULL,
first_name VARCHAR2(12) NOT NULL,
last_name VARCHAR2(30) NOT NULL,
-- Τα χρήματα που έχει ένας πελάτης στο λογαριασμό του.
credit NUMBER(5, 2) DEFAULT 0 NOT NULL,
CONSTRAINT cust_pk PRIMARY KEY (cust_id),
-- Μόνο ένας λογαριασμός για κάθε σπίτι.
CONSTRAINT phone_unique UNIQUE (phone_number)
)
/

DROP SEQUENCE cust_id_seq
/

CREATE SEQUENCE cust_id_seq MINVALUE 10000 MAXVALUE 99999 INCREMENT BY 1 START WITH 10000 NOCACHE  NOCYCLE ORDER

/

Yiannis P.

Answer 1

I think you should change CREATE SEQUENCE cust_id_seq ... INCREMENT BY1 to ... INCREMENT BY50. Here is why.

The declared sequence increment should match the @SequenceGenerator's allocationSize parameter. allocationSize is not specified and therefore defaults to 50. But the true INCREMENT BY is only 1, not 50. So there is a mismatch between allocationSize and the real INCREMENT BY.

Here's how this mismatch could cause the problem. TopLink Essentials (TLE) calls NEXTVAL() on cust_id_seq. The sequence returns 10000 + 1. TLE assumes the sequence just incremented by 50 (default JPA allocationSize) instead of 1 (actual amount). TLE subtracts allocationSize = 50 from 10001 to get 9951.

By the way, if you have the freedom to do so, consider upgrading to TLE's successor, EclipseLink (and to Glassfish v3).

Answer 2

In the customer entity in the annotation @SequenceGenerator I added the atribute allocationSize with value 1, now the primary keys start from 10000.

@Entity
@Table(name = "customer")
@SequenceGenerator(name="seq", sequenceName="cust_id_seq", allocationSize=1)
public class Customer implements Serializable
{

    @Id
    @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="seq")
    @Column(name="CUST_ID")
    private int id;  
...
}