使用JPA和c3p0的Oracle lob预取

Question

我需要提高Java JPA应用程序中Oracle lob检索的性能。

使用oracle.jdbc.defaultLobPrefetchSize参数对性能进行了很好的记录，但是该文档适用于诸如OracleConnection或OracleStatement之类的低级类。

如何在c3p0，JPA上下文中设置此lob设置？

在连接级别：

@Bean
public DataSource dataSource() throws SQLException, PropertyVetoException {       
    ComboPooledDataSource dataSource = new ComboPooledDataSource();
    dataSource.setJdbcUrl(this.dbProperties.getProperty("jdbc.url"));
    dataSource.setUser(this.dbProperties.getProperty("jdbc.username"));
    datasource.setPassword(this.dbProperties.getProperty("jdbc.password"));
    dataSource.setDriverClass(this.dbProperties.getProperty("jdbc.driver"));            
    return dataSource;
}

@Bean
public LocalContainerEntityManagerFactoryBean myEmf() throws SQLException, PropertyVetoException {
    LocalContainerEntityManagerFactoryBean lef = new LocalContainerEntityManagerFactoryBean();
    lef.setDataSource(dataSource());
    lef.setJpaVendorAdapter(jpaVendorAdapter());            
    lef.setJpaProperties(this.dbProperties);        
    return lef;
}

在查询级别：

@Transactional(readOnly=true)
public List<Data> findByXXX(String xxx) {        
    // Make/execute the typed query.
    return this.entityManager.createQuery("SELECT d FROM Data d WHERE d.xxx = :xxx", Data.class)
            .setParameter("xxx", xxx)
            .getResultList();
}

谢谢。