mysql 版本:
+------------------+
| version() |
+------------------+
| 5.1.41-community |
+------------------+表定义CREATE TABLE `t2` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(5) DEFAULT NULL,
`c` decimal(5,3) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `id` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=145 DEFAULT CHARSET=latin1;测试一:
存储过程pp1:
CREATE DEFINER=`root`@`localhost` PROCEDURE `pp1`()
beginDECLARE i varchar(200) ;SET TRANSACTION ISOLATION LEVEL Serializable ;start transaction ;select name into i from t2 where id=3;select * from t2 where id=3;select sleep(10); select * from t2 where id=3;update t2 set name='pp1' where id=3;select * from t2 where id=3;commit ;end;
存储过程pp2:
CREATE DEFINER=`root`@`localhost` PROCEDURE `pp2`()
beginSET TRANSACTION ISOLATION LEVEL Serializable ;start transaction ;/* select * from t2 where id=3 for update; */ select * from t2 where id=3 ;insert into t2 (name ) values('test'); /*update t2 set name='pp2' where id=3 ;*/select * from t2 where id=3 ;commit;end;打开2个控制台 一个执行 call pp1; 另一执行call pp2;
先执行call pp1;再 pp1睡眠时间里 再另一个控制台 执行pp2;
这里定义事务隔离级别为Serializable 原理上pp2再pp1执行过程中是不可以插入的 ,但是结果往往令人失望,2个控制台都执行成功 我快崩溃了
继续换成事务隔离级别 REPEATABLE READ 测试mysql事务隔离效果
测试二:
存储过程pp1:
CREATE DEFINER=`root`@`localhost` PROCEDURE `pp1`()
beginDECLARE i varchar(200) ;SET TRANSACTION ISOLATION LEVEL REPEATABLE READ ;start transaction ;select name into i from t2 where id=3;select * from t2 where id=3;select sleep(10); select * from t2 where id=3;update t2 set name='pp1' where id=3;select * from t2 where id=3;commit ;end;
存储过程pp2:
CREATE DEFINER=`root`@`localhost` PROCEDURE `pp2`()
beginSET TRANSACTION ISOLATION LEVEL REPEATABLE READ ;start transaction ;/* select * from t2 where id=3 for update; */ select * from t2 where id=3 ;/*insert into t2 (name ) values('test'); */update t2 set name='pp2' where id=3 ;select * from t2 where id=3 ;commit;end;测试方法和测试一类似 结果令人失望 mysql执行成功了 测试三:
在sqlserver2000下 修改上述代码 通过测试 REPEATABLE READ,Serializable 都测试成功
代码略
这是何故啊 ???
+------------------+
| version() |
+------------------+
| 5.1.41-community |
+------------------+表定义CREATE TABLE `t2` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(5) DEFAULT NULL,
`c` decimal(5,3) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `id` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=145 DEFAULT CHARSET=latin1;测试一:
存储过程pp1:
CREATE DEFINER=`root`@`localhost` PROCEDURE `pp1`()
beginDECLARE i varchar(200) ;SET TRANSACTION ISOLATION LEVEL Serializable ;start transaction ;select name into i from t2 where id=3;select * from t2 where id=3;select sleep(10); select * from t2 where id=3;update t2 set name='pp1' where id=3;select * from t2 where id=3;commit ;end;
存储过程pp2:
CREATE DEFINER=`root`@`localhost` PROCEDURE `pp2`()
beginSET TRANSACTION ISOLATION LEVEL Serializable ;start transaction ;/* select * from t2 where id=3 for update; */ select * from t2 where id=3 ;insert into t2 (name ) values('test'); /*update t2 set name='pp2' where id=3 ;*/select * from t2 where id=3 ;commit;end;打开2个控制台 一个执行 call pp1; 另一执行call pp2;
先执行call pp1;再 pp1睡眠时间里 再另一个控制台 执行pp2;
这里定义事务隔离级别为Serializable 原理上pp2再pp1执行过程中是不可以插入的 ,但是结果往往令人失望,2个控制台都执行成功 我快崩溃了
继续换成事务隔离级别 REPEATABLE READ 测试mysql事务隔离效果
测试二:
存储过程pp1:
CREATE DEFINER=`root`@`localhost` PROCEDURE `pp1`()
beginDECLARE i varchar(200) ;SET TRANSACTION ISOLATION LEVEL REPEATABLE READ ;start transaction ;select name into i from t2 where id=3;select * from t2 where id=3;select sleep(10); select * from t2 where id=3;update t2 set name='pp1' where id=3;select * from t2 where id=3;commit ;end;
存储过程pp2:
CREATE DEFINER=`root`@`localhost` PROCEDURE `pp2`()
beginSET TRANSACTION ISOLATION LEVEL REPEATABLE READ ;start transaction ;/* select * from t2 where id=3 for update; */ select * from t2 where id=3 ;/*insert into t2 (name ) values('test'); */update t2 set name='pp2' where id=3 ;select * from t2 where id=3 ;commit;end;测试方法和测试一类似 结果令人失望 mysql执行成功了 测试三:
在sqlserver2000下 修改上述代码 通过测试 REPEATABLE READ,Serializable 都测试成功
代码略
这是何故啊 ???
mysql鸟都不鸟你 一股脑儿什么都执行了 ,如果这是个转账的程序 ,就悲剧了,混不下去了
放到UPDATE后面看看。select sleep(10);前面都是SELECT,没有给表加X锁。
如果是sqlserver2000的话就自动加排它锁 X锁
mysql如果还是手动加个排它锁 设置事务还有什么用