求问 Mybatis 的缓存

This topic created in 1593 days ago, the information mentioned may be changed or developed.

已经将一级缓存设置为了 statement ，关闭了二级缓存

mybatis: configuration: cache-enabled: false local-cache-scope: statement

测试

 @GetMapping("/test") @Transactional public User test() throws InterruptedException { User user = userMapper.selectById(1); System.out.println(user); TimeUnit.SECONDS.sleep(5); User user2 = userMapper.selectById(1); System.out.println(user2); return user2; }

疑问

2022-01-01 19:33:18.320 DEBUG 49182 --- [nio-8000-exec-4] com.ding.mapper.UserMapper.selectById : ==> Preparing: SELECT * FROM `user` WHERE id = ? 2022-01-01 19:33:18.321 DEBUG 49182 --- [nio-8000-exec-4] com.ding.mapper.UserMapper.selectById : ==> Parameters: 1(Integer) 2022-01-01 19:33:18.322 DEBUG 49182 --- [nio-8000-exec-4] com.ding.mapper.UserMapper.selectById : <== Total: 1 User(id=1, username=test, password=222, phOne=) 2022-01-01 19:33:23.327 DEBUG 49182 --- [nio-8000-exec-4] com.ding.mapper.UserMapper.selectById : ==> Preparing: SELECT * FROM `user` WHERE id = ? 2022-01-01 19:33:23.327 DEBUG 49182 --- [nio-8000-exec-4] com.ding.mapper.UserMapper.selectById : ==> Parameters: 1(Integer) 2022-01-01 19:33:23.328 DEBUG 49182 --- [nio-8000-exec-4] com.ding.mapper.UserMapper.selectById : <== Total: 0 User(id=1, username=test, password=222, phOne=)

日志是打印了两遍 sql ，在休眠的 5 秒前我已经在数据库把这条数据清空了，但是第二次执行的结果返回的还是和第一次一样

Supplement 1 Jan 1, 2022

总结：
Spring 中
1. mybatis 的一级缓存默认为 session ，但是只有在事务中缓存才会生效，也就是相同的两次查询只会执行一次
2. 如果碰到这种情况则是隔离级别导致的。修改为 read committed 即可。Spring 的隔离级别默认是和数据库一致的
如果不想修改数据库的隔离级别，则要在指定 Transactional 中指定 isolation

5 replies 2022-01-02 09:57:12 +08:00