JPA persist() or merge()

Question

Hi All,
I would like to get clarification between using JPA persist() and merge() where there is a OneToMany EMPLOYEE table unidirectionally joint to ManyToOne TELEPHONE table.
The code snippet for OneToMany Employee.java entity object is as follows:
@Entity
@IdClass(EmployeePK.class)
@Table(name="EMPLOYEE", catalog="CorporationDB", schema="")
public class Employee implements Serializable {  
@OneToMany(cascade={CascadeType.ALL}, fetch=FetchType.EAGER)
    @JoinTable(name="EMPLOYEE_TELEPHONE", catalog="CorporationDB", schema="",
               joinColumns={@JoinColumn(name="FIRSTNAME", referencedColumnName="FIRSTNAME"),
                            @JoinColumn(name="SURNAME", referencedColumnName="SURNAME"),
                            @JoinColumn(name="AGE", referencedColumnName="AGE"),
                            @JoinColumn(name="SEX", referencedColumnName="SEX")},
               inverseJoinColumns={@JoinColumn(name="TELEPHONE_ID")})
        private Collection<Telephone> telephones = new ArrayList<Telephone>();
    public Collection<Telephone> getTelephones()
     return telephones;
    public void setTelephones(Collection<Telephone> telephones)
     this.telephones = telephones;
    }The corresponding detail for ManyToOne Telephone.java entity object is:
@Entity
@Table(name="TELEPHONE", catalog="CorporationDB", schema="")
public class Telephone implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="ID")
    private int id;
    @Column(name="TELEPHONE")
    private String telephone;
    public void setTelephone(String telephone) {
        this.telephone = telephone;
    public String getTelephone() {
        return telephone;
    }I would like JPA to to ignore (not overwrite) existing record and only add newer unique telephone numbers. persist() does that except it is throwing the following exceptions and continually re-trying to insert the duplicate records:
Local Exception Stack:
*Exception [TOPLINK-4002] (Oracle TopLink Essentials - 2.1 (Build b60e-fcs (12/23/2008))): oracle.toplink.essentials.exceptions.DatabaseException*
Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry Allan-Smith-20-M' for key 'PRIMARY'
Error Code: 1062
Call: INSERT INTO CorporationDB.EMPLOYEE (FIRSTNAME, SURNAME, AGE, SEX.....) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
*bind => [Allan, Smith, 20, M,....]*
Query: InsertObjectQuery(finance.Employee@1d2d80c)
JTS5054: Unexpected error occurred in after completion
On the other hand, merge() ignores (does not add) duplicate Employee record (good) but it still duplicates the ManyToOne TELEPHONE table. Is it because of the OneToMany(cascade={CascadeType.ALL}} property in Employee.java which duplicates TELEPHONE records automatically? As a result, how to ensure that only unique OneToMany (EMPLOYEE) & ManyToOne (TELEPHONE) records are added once?
persist() seems to work fine except that it is continually erroring out instead of skipping to the next new record.
This Java EE 5 application is running properly.
I am running JDK1.6.0_7, GF2.1 and MySQL on Windows XP.
Thanks in advance,
Jack

Answer 1

I would recommend you continue to use TopLink Essentials as your JPA provider by setting your provider in your persistence.xml, or upgrading to EclipseLink and setting it as your provider. The latest WLS release also includes EclipseLink.
James : http://www.eclipselink.org