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EclipseLink/Examples/JPA/PessimisticLocking

EclipseLink allows users the option of using pessimistic locking on their queries. This is done through the use of a query hint.

See:

  • org.eclipse.persistence.jpa.config.EclipseLinkQueryHints
  • org.eclipse.persistence.jpa.config.PessimisticLock
  • Configuring a Locking Policy in the EclipseLink User's Guide

Via Annotations

@Entity
@Table(name="JPA_EMPLOYEE")
@NamedQuery(
  name="findEmployeeByPK",
  query="SELECT OBJECT(employee) FROM Employee employee WHERE employee.id = :id"),
  hints={
    @QueryHint(
      name=EclipseLinkQueryHints.PESSIMISTIC_LOCK, 
      value=PessimisticLock.Lock)
  }
)
public class Employee implements Serializable {
...

}

Via XML

<entity name="Employee" class="org.eclipse.testing.Employee" access="PROPERTY">
  ...
  <named-query name="findEmployeeByPK">
    <query>SELECT OBJECT(employee) FROM Employee employee WHERE employee.id = :id</query>
    <hint name="eclipselink.pessimistic-lock" value="Lock">
  </named-query>
  ...
</entity>