hibernate - 获取数据时在 hibernate 状态下是否需要 `session.getTransaction().commit();`

Question

我想知道

是 session.getTransaction().commit();获取数据时在 hibernate 状态下需要

private List listEvents() {
        Session session = HibernateUtil.getSessionFactory().getCurrentSession();
        session.beginTransaction();
        List result = session.createQuery("from Event").list();
        session.getTransaction().commit();
        return result;
    }

此示例取自 http://docs.jboss.org/hibernate/orm/4.1/manual/en-US/html_single/#tutorial-firstapp-firstclass

Answer 1

是的，您甚至需要一个事务来进行读取操作，并且应该按照 hibernate 文档提交它。

以下是详细信息:

13.2. Database transaction demarcation

Database, or system, transaction boundaries are always necessary. No communication with the database can occur outside of a database transaction (this seems to confuse many developers who are used to the auto-commit mode). Always use clear transaction boundaries, even for read-only operations. Depending on your isolation level and database capabilities this might not be required, but there is no downside if you always demarcate transactions explicitly. Certainly, a single database transaction is going to perform better than many small transactions, even for reading data.

在普通 JDBC 的情况下，默认情况下启用自动提交。以下是它的详细信息:

Disabling Auto-Commit Mode

When a connection is created, it is in auto-commit mode. This means that each individual SQL statement is treated as a transaction and is automatically committed right after it is executed. (To be more precise, the default is for a SQL statement to be committed when it is completed, not when it is executed. A statement is completed when all of its result sets and update counts have been retrieved. In almost all cases, however, a statement is completed, and therefore committed, right after it is executed.)