java刷新Hibernate会话需要很长时间
我正在使用Hibernate 5.2.8。最终版本,我们需要从数据库中读取数百万数据,并通过一些业务逻辑更新数据,因为我的数据库很大,我希望在达到batchsize后提交数据,所以我编写了以下代码
Session session = HibernateUtil.getSessionFactory().getCurrentSession();
session.getTransaction().begin();
Query<Object> query = session.createQuery(SQL, Object.class);
ScrollableResults scrollableResults = query.setCacheMode(CacheMode.IGNORE)
.scroll(ScrollMode.FORWARD_ONLY);
int count = 0;
while (scrollableResults.next())
{
Object object = (Object) scrollableResults.get(0);
process(object)
session.update(object);
if (++count % batchSizeDeclare== 0)
{
session.flush();
session.clear();
LOGGER.info("Updated batch records");
}
}
session.getTransaction().commit();
LOGGER.info("commited in Hibernate ");
}
下面是我的hibernate.cfg.xml
文件
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- Database connection settings -->
<property name="connection.driver_class">com.microsoft.sqlserver.jdbc.SQLServerDriver</property>
<property name="connection.url">jdbc:sqlserver://com;database=DEV</property>
<property name="connection.username">user</property>
<property name="connection.password">pass</property>
<property name="hibernate.default_schema">schema</property>
<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">5</property>
<!-- SQL dialect -->
<property name="dialect">org.hibernate.dialect.SQLServer2012Dialect</property>
<!-- Disable the second-level cache -->
<property name="cache.provider_class">org.hibernate.cache.internal.NoCacheProvider</property>
<!-- Echo all executed SQL to stdout -->
<!-- <property name="show_sql">true</property> -->
<!-- <property name="format_sql">true</property> -->
<!-- Drop and re-create the database schema on startup -->
<property name="hbm2ddl.auto">update</property>
<!-- org.hibernate.HibernateException: No CurrentSessionContext configured! -->
<property name="hibernate.current_session_context_class">thread</property>
<property name="hibernate.jdbc.batch_size">100</property>
<property name="hibernate.c3p0.min_size">5</property>
<property name="hibernate.c3p0.max_size">20</property>
<property name="hibernate.c3p0.timeout">300</property>
<property name="hibernate.c3p0.max_statements">50</property>
<property name="hibernate.c3p0.idle_test_period">3000</property>
<mapping class="com.beans.Object" />
</session-factory>
</hibernate-configuration>
下面是我的Object.java
public class Object implements Serializable
{
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "ID", nullable = false, unique = true, updatable = false)
private int id;
private String filePath;
private String fileName;
private String mimeType;
private double fileSize;
// removed getters and setters
}
一旦我的代码到达会话。flush()即使等待30分钟,它也不会做任何事情。这是批量提交的正确方法吗?如何批量更新
# 1 楼答案
相反,数据库似乎做得太多了。只是你看不到任何进展,因为数据库正在努力处理你提交的大量工作
简而言之,答案是否定的
您不必从数据库中获取数百万行。您有更好的选择: