MySQL模拟Oralce闪回操作

在前面的文章中我们介绍了MySQL误操作后数据恢复(update,delete忘加where条件),大概操作是通过sed命令把binlog中相关SQL误操作给逆向回来，然后导入SQL文件来恢复错误操作，sed相关命令也比较复杂。如果没有正则基础的同学肯定搞不清楚在干嘛。今天无意中发现淘宝的大神（翻译高性能mysql第三版的作者之一）开发了一个补丁，该补丁能够模拟Oracle的闪回操作，这样以来我们的MySQL也可以实现闪回咯。真是给力。注意：同样binlog格式需要是ROW

项目主页：http://mysql.taobao.org/index.php/Patch_source_code#Add_flashback_feature_for_mysqlbinlog

测试过程 

1.给mysql打补丁，该补丁是针对mysql 5.5.18的版本，我测试的mysql 5.5.25版本也可以。（也可以使用我编译好了的，64位平台下的，在文中最后会有下载地址）

wget http://mysql.taobao.org/images/0/0f/5.5.18_flashback.diff
cd /usr/local/src/mysql-5.5.25a/
patch -p0 < /root/5.5.18_flashback.diff
cmake -DCMAKE_INSTALL_PREFIX=/usr/local/mysql
make && make install

2.检查补丁是否应用成功，如果mysqlbinlog命令多了-B选项，那么就ok了。

[root@yayun-mysql-server ~]# mysqlbinlog --help | grep '\-B'
  -B, --flashback     Flashback data to start_postition or start_datetime.
[root@yayun-mysql-server ~]# 

3.模拟误操作（update忘记加where条件）

(root@yayun-mysql-server) [test]> select * from tb1;
+------+--------+
| id   | name   |
+------+--------+
|    1 | yayun  |
|    2 | atlas  |
|    3 | dyy    |
|    4 | nginx  |
|    5 | apache |
+------+--------+
5 rows in set (0.00 sec)

(root@yayun-mysql-server) [test]> update tb1 set name='yayun';
Query OK, 4 rows affected (0.03 sec)
Rows matched: 5  Changed: 4  Warnings: 0

(root@yayun-mysql-server) [test]> select * from tb1;
+------+-------+
| id   | name  |
+------+-------+
|    1 | yayun |
|    2 | yayun |
|    3 | yayun |
|    4 | yayun |
|    5 | yayun |
+------+-------+
5 rows in set (0.00 sec)

(root@yayun-mysql-server) [test]> 

4.开始恢复

（1）首先需要找出错误的操作语句以及position点。

(root@yayun-mysql-server) [test]> show master status;
+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000023 |      364 |              |                  |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)

(root@yayun-mysql-server) [test]> 

可见现在正在使用的是mysql-bin.000023这个binlog

[root@yayun-mysql-server mysql]# mysqlbinlog -vv mysql-bin. |egrep -i -C  'update|tb1'
# Warning: this binlog is either in use or was not closed properly.
BINLOG '
RgZoUw8BAAAAZwAAAGsAAAABAAQANS41LjI1YS1sb2cAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAEzgNAAgAEgAEBAQEEgAAVAAEGggAAAAICAgCAA==
'/*!*/;
# at 107
#140506  5:45:21 server id 1  end_log_pos 175   Query   thread_id=3     exec_time=0     error_code=0
SET TIMESTAMP=/*!*/;
SET @@session.pseudo_thread_id=/*!*/;
SET @@session.foreign_key_checks=, @@session.sql_auto_is_null=, @@session.unique_checks=, @@session.autocommit=/*!*/;
SET @@session.sql_mode=/*!*/;
SET @@session.auto_increment_increment=, @@session.auto_increment_offset=/*!*/;
/*!\C utf8 *//*!*/;
SET @@session.character_set_client=,@@session.collation_connection=,@@session.collation_server=/*!*/;
SET @@session.lc_time_names=/*!*/;
SET @@session.collation_database=DEFAULT/*!*/;
BEGIN
/*!*/;
# at
# at
#  :: server id   end_log_pos    Table_map: `test`.`tb1` mapped to number 
#140506  5:45:21 server id 1  end_log_pos 337   Update_rows: table id 35 flags: STMT_END_F

BINLOG '
cQZoUxMBAAAALQAAANwAAAAAACMAAAAAAAEABHRlc3QAA3RiMQACAw8CPAAD
cQZoUxgBAAAAdQAAAFEBAAAAACMAAAAAAAEAAv///AIAAAAFYXRsYXP8AgAAAAV5YXl1bvwDAAAA
A2R5efwDAAAABXlheXVu/AQAAAAFbmdpbnj8BAAAAAV5YXl1bvwFAAAABmFwYWNoZfwFAAAABXlh
eXVu
'/*!*/;
### UPDATE test.tb1
### WHERE
###   @= /* INT meta=0 nullable=1 is_null=0 */
###   @='atlas' /* VARSTRING(60) meta=60 nullable=1 is_null=0 */
### SET
###   @= /* INT meta=0 nullable=1 is_null=0 */
###   @='yayun' /* VARSTRING(60) meta=60 nullable=1 is_null=0 */
### UPDATE test.tb1
### WHERE
###   @= /* INT meta=0 nullable=1 is_null=0 */
###   @='dyy' /* VARSTRING(60) meta=60 nullable=1 is_null=0 */
### SET
###   @= /* INT meta=0 nullable=1 is_null=0 */
###   @='yayun' /* VARSTRING(60) meta=60 nullable=1 is_null=0 */
### UPDATE test.tb1
### WHERE
###   @= /* INT meta=0 nullable=1 is_null=0 */
###   @='nginx' /* VARSTRING(60) meta=60 nullable=1 is_null=0 */
### SET
###   @= /* INT meta=0 nullable=1 is_null=0 */
###   @='yayun' /* VARSTRING(60) meta=60 nullable=1 is_null=0 */
### UPDATE test.tb1
### WHERE
###   @= /* INT meta=0 nullable=1 is_null=0 */
###   @='apache' /* VARSTRING(60) meta=60 nullable=1 is_null=0 */
### SET
###   @= /* INT meta=0 nullable=1 is_null=0 */
###   @='yayun' /* VARSTRING(60) meta=60 nullable=1 is_null=0 */
# at
#  :: server id   end_log_pos    Xid =
COMMIT/*!*/;
DELIMITER ;
# End of log file
ROLLBACK /* added by mysqlbinlog */;
/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;

开始的起点以107为准，因为107下面紧跟着BEGIN，结束的点以end_log_pos 337下一个点为准.

[root@yayun-mysql-server mysql]# mysqlbinlog -vv --start-position= mysql-bin.
/*!40019 SET @@session.max_insert_delayed_threads=0*/;
/*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
DELIMITER /*!*/;
# at
#  :: server id   end_log_pos    Start: binlog v , server v 5.5.25a-log created   ::
# Warning: this binlog is either in use or was not closed properly.
BINLOG '
RgZoUw8BAAAAZwAAAGsAAAABAAQANS41LjI1YS1sb2cAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAEzgNAAgAEgAEBAQEEgAAVAAEGggAAAAICAgCAA==
'/*!*/;
# at 337
#140506  5:45:21 server id 1  end_log_pos 364   Xid = 40
COMMIT/*!*/;
DELIMITER ;
# End of log file
ROLLBACK /* added by mysqlbinlog */;
/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
[root@yayun-mysql-server mysql]# 

上面蓝色字体显示的很清楚了，那么结束的点就是364，因为下面紧跟着COMMIT。现在我们已经找到了日志开始起点为107，结束点为364，下面开始恢复。

[root@yayun-mysql-server mysql]# mysqlbinlog -B -vv --start-position= --stop-position= mysql-bin. | mysql
[root@yayun-mysql-server mysql]# 

检查是否恢复成功：

(root@yayun-mysql-server) [test]> select * from tb1;
+------+--------+
| id   | name   |
+------+--------+
|    1 | yayun  |
|    2 | atlas  |
|    3 | dyy    |
|    4 | nginx  |
|    5 | apache |
+------+--------+
5 rows in set (0.00 sec)

(root@yayun-mysql-server) [test]> 

可见数据已经成功恢复。其实原理和我们前面通过sed操作binlog进行恢复是一样的。只是这个更简单。对于delete忘记添加where条件，恢复方法是一样的。这里不再重复。

总结:

binlog格式非常重要，无论是数据恢复还是主从复制，ROW格式都非常的给力。当然也有缺点，复制会占用过多带宽，消耗大量磁盘空间。

已经应用补丁的mysqlbinlog下载地址（64位平台，直接替换原来的即可）

http://pan.baidu.com/s/1o6jXt14