-- Base Log record type.
CREATE TABLE LOG_RECORD(
   ID INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY,
        DATE_CREATED TIMESTAMP,
);

-- Specific text flavour of log record.
CREATE TABLE TXT_LOG(
   LOG_EVENT_ID INTEGER NOT NULL,

   DESCRIPTION VARCHAR(700) NOT NULL
);

-- A log entity is the parent object, it has a number of log records...
CREATE TABLE LOG (
   ID INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY,
   .....
);

-- The log record association is modelled by this table, marking a log record against a specific
-- Note, no FKs defined - assume hibernate will handle sets as expected.
CREATE TABLE LOG_ASSOCIATION(
        LOG_ID INTEGER NOT NULL,
        LOG_RECORD_ID INTEGER NOT NULL
);

@Entity
class Log{
   ...
   Set<LogRecord> logRecords = new HashSet<LogRecord>();
   ....

   @OneToMany(fetch = FetchType.LAZY, cascade = {CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REFRESH, CascadeType.REMOVE})
   @JoinTable(   uniqueConstraints = @UniqueConstraint(columnNames = {"LOG_ID", "LOG_RECORD_ID" }),
         name = "LOG_ASSOCIATION", joinColumns = @JoinColumn(name = "LOG_ID"), inverseJoinColumns = @JoinColumn(name = "LOG_RECORD_ID"))
   public Set<LogRecordt> getLogRecords()
   {....
   }
}

   <bean id="bussinessService" class=com.spike.logger.business.LogService">
      <property name="MyDAO" ref="MyDAOTarget" />
   </bean>

   <!-- Configure Hibernate SessionFactory -->
   <bean id="sessionFactory"
      class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">

      <property name="hibernateProperties">
         <props>
            <prop key="hibernate.connection.driver_class">org.apache.derby.jdbc.EmbeddedDriver</prop>
            ....etc...
         </props>
      </property>
      <property name="annotatedClasses">
         <list>   .....</list>
      </property>
   </bean>

   <!--sessionFactory will get autowired-->
   <bean id="hibernateInterceptor" class="org.springframework.orm.hibernate3.HibernateInterceptor" autowire="byName" />
   
   <!--sessionFactory will get autowired-->
   <bean id="MyDAOTarget" class="com.spike.logger.dao.MyDAOImpl" autowire="byName" />
   
   <bean id="MyDAO" class="org.springframework.aop.framework.ProxyFactoryBean">
      <property name="proxyInterfaces" value="com.spike.logger.dao.MyDAO" />
      <property name="interceptorNames">
         <list>
            <value>hibernateInterceptor</value>
            <value>MyDAOTarget</value>
         </list>
      </property>
   </bean>

Cause: org.springframework.orm.hibernate3.HibernateSystemException: Illegal attempt to associate a collection with two open sessions; nested exception is org.hibernate.HibernateException: Illegal attempt to associate a collection with two open sessions

public void saveLog(Log log)   {
   getHibernateTemplate().merge(response);
}

// @NamedQuery(name="log.getLog", query="from Log l where l.id = :log_id")
//
public Log getLog(Integer log_id)   {
   org.hibernate.Query q = getSession().getNamedQuery("log.getLog");
   q.setInteger("log_id", log_id);
   q.setString("group_name", group);
   return (Log) q.uniqueResult();
}

public void saveLog(Log log)   {
   getHibernateTemplate().saveOrUpdate(response);
}

public Log getLog(String group, Integer log_id)   {
   String query = "from Log l where l.id = ? ";

   Object[] parameters = { log_id };

   List<Log> logs = (List<Log>) getHibernateTemplate().find(query, parameters);
   Log log = logs.iterator().next();
   return log;
}