关于二级缓存的commit
来源：2-1 MyBatis二级缓存-1
三金好同学
2019-10-31 23:18:18
@Test
public void selectById2() throws Exception {
SqlSession session = null;
try {
session = MyBatisUtils.openSession();
Goods g = session.selectOne("selectById", 740);
System.out.println(g.hashCode());
} catch (Exception e) {
throw e;
} finally {
MyBatisUtils.closeSession(session);
}
try {
session = MyBatisUtils.openSession();
session.commit();
System.out.println("二级缓存============");
Goods g1 = session.selectOne("selectById", 740);
System.out.println(g1.hashCode());
} catch (Exception e) {
throw e;
} finally {
MyBatisUtils.closeSession(session);
}
}<cache eviction="LRU" flushInterval="600000" size="512" readOnly="true"/>
[main] 23:11:22:963 DEBUG org.apache.ibatis.logging.LogFactory - Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter. [main] 23:11:22:978 DEBUG o.a.i.d.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections. [main] 23:11:22:979 DEBUG o.a.i.d.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections. [main] 23:11:22:979 DEBUG o.a.i.d.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections. [main] 23:11:22:979 DEBUG o.a.i.d.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections. [main] 23:11:23:096 DEBUG goods - Cache Hit Ratio [goods]: 0.0 [main] 23:11:23:103 DEBUG o.a.i.t.jdbc.JdbcTransaction - Opening JDBC Connection [main] 23:11:24:817 DEBUG o.a.i.d.pooled.PooledDataSource - Created connection 1565740893. [main] 23:11:24:817 DEBUG o.a.i.t.jdbc.JdbcTransaction - Setting autocommit to false on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@5d534f5d] [main] 23:11:24:822 DEBUG goods.selectById - ==> Preparing: select * from t_goods where goods_id = ? [main] 23:11:24:859 DEBUG goods.selectById - ==> Parameters: 740(Integer) [main] 23:11:24:895 DEBUG goods.selectById - <== Total: 1 1807648168 [main] 23:11:24:899 DEBUG o.a.i.t.jdbc.JdbcTransaction - Resetting autocommit to true on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@5d534f5d] [main] 23:11:24:900 DEBUG o.a.i.t.jdbc.JdbcTransaction - Closing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@5d534f5d] [main] 23:11:24:900 DEBUG o.a.i.d.pooled.PooledDataSource - Returned connection 1565740893 to pool. 开启二级缓存============ [main] 23:11:24:900 DEBUG goods - Cache Hit Ratio [goods]: 0.5 1807648168
我设置了session.commit()方法，为什么namespace没有清除缓存，
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1回答
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同学你好！
SqlSession执行更新操作（update、delete、insert）后并执行SqlSession.commit()时，不仅清空其自身的一级缓存（执行更新操作的结果），也清空二级缓存
但是在查询时，commit是不会清除二级缓存的，所以同学这里没有效果
由于查询操作其实并不会改变数据，因此对数据没有影响。所以我们通常会说commit之后会将二级缓存也清空。这里老师有一些疏忽，很抱歉给同学带来疑惑，还望同学见谅。这里的问题我们会反馈给相关工作人员~
如果我的回答解决了你的疑惑，请采纳，祝学习愉快~
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