java - hibernate :flush() 和 commit()

Question

单独调用 org.hibernate.Session.flush() 是个好习惯吗？

正如 org.hibernate.Session 文档中所说，

Must be called at the end of a unit of work, before commiting the transaction and closing the session (depending on flush-mode, Transaction.commit() calls this method).

如果 org.hibernate.Transaction.commit() 已经可以调用 flush()，你能解释一下调用的目的吗？

Answer 1

在 Hibernate Manual 你可以看到这个例子

Session session = sessionFactory.openSession();
Transaction tx = session.beginTransaction();

for (int i = 0; i < 100000; i++) {
    Customer customer = new Customer(...);
    session.save(customer);
    if (i % 20 == 0) { // 20, same as the JDBC batch size
        // flush a batch of inserts and release memory:
        session.flush();
        session.clear();
    }
}

tx.commit();
session.close();

如果不调用 flush 方法，你的一级缓存会抛出 OutOfMemoryException

Also you can look at this post about flushing