MySQL中truncate误操作后的数据恢复案例
实际线上的场景⽐较复杂，当时涉及了truncate, delete 两个操作，经确认丢数据差不多7万多⾏，等停下来时，差不多⼜有共计1万多⾏数据写⼊。这⾥为了简单说明，只拿弄⼀个简单的业务场景举例。
测试环境： Percona-Server-5.6.16
⽇志格式： mixed 没起⽤gtid
表结构如下：
CREATE TABLE `tb_wubx` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(32) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8
CREATE TABLE `tb_wubx` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(32) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8
基于某个时间点有⼀个备份或是有全量的binlog是能恢复数据的⼀个唯⼀保证。例如我们的备份就是⼀个表结构创建语
句,binlog pos相关信息： mysql-bin.000004 , 4，然后进⾏了如下：
–t1时间程序写⼊：
insert into tb_wubx(name) values(‘张三'),(‘李四');
insert into tb_wubx(name) values(‘隔壁⽼王');
–t2时间某个⼈员失误
truncate table tb_wubx;
–t3时间程序写⼊
insert into tb_wubx(name) values(‘⽼赵');
update tb_wubx set name='⽼赵赵' where id=1;
现在表⾥的数据情况：
mysql>select * from tb_wubx;
+----+-----------+
| id | name |
+----+-----------+
| 1 | ⽼赵赵 |
+----+-----------+
1 row in set (0.00 sec)
mysql>select * from tb_wubx;
+----+-----------+
| id | name |
+----+-----------+
| 1 | ⽼赵赵 |
+----+-----------+
1 row in set (0.00 sec)
可以见truncate table操作后，表的⾃增id⼜变更为从1开始，原来写⼊的数据应该是：
+—-+———–+
| id | name |
+—-+———–+
| 1 | 张三 |
+—-+———–+
| 2 | 李四 |
+—-+———–+
| 3 | 隔壁⽼王 |
+—-+———–+
如果没⽣truncate table操作，实际的数据应该为：
+—-+———–+
| id | name |
+—-+———–+
| 1 | 张三 |
+—-+———–+
| 2 | 李四 |
+—-+———–+
| 3 | 隔壁⽼王 |
+—-+———–+
| 4 | ⽼赵赵 |
+—-+———–+
⽽且线上的恢复那个表时和序序开发⼈员了解才知道，原来那个id和缓存及其它地⽅有依赖，因为id乱了，也会造成程序错乱。这个时间修复id在程序层错乱的事，留给开发⼈员了关建是给他们讲明⽩恢复的结果是什么样，我们的关建任务是把数据恢复出来。好，接下来的⼯作是开始从binlog中恢复数据。
利⽤: show binary logs; 查看当的log⽂件分布，然后利⽤show binlog events in ‘binary log⽂件'; 查看log⽂件的内容，⽬的是到truncate发⽣的⽇志位置。
另外因为基于备份（由log的启始位置）或是从量log, 如果基于备份有log的起始位置，我们需要处理的log⽂件是启始位置到发⽣truncate的⽇值（后⾯的数据处理不了，会发⽣主建冲突的错误造成truncate后的数据不能恢复），
如果是全量⽇志，需要从创建完mysql后库后的⽇志去处理到当前的发⽣truncate的位置（后⾯数据会因为主建冲突写不进去）
恢复准备⼯作，创建⼀个库⽤于恢复数据，这⾥创建了⼀个re_wubx, 及原结构的表: tb_wubx （相当于恢复了备份，过程省略）
mysql> show binary logs;
+------------------+-----------+
mysql数据库损坏修复| Log_name | File_size |
+------------------+-----------+
| mysql-bin.000001 | 143 |
| mysql-bin.000002 | 261 |
| mysql-bin.000003 | 562 |
| mysql-bin.000004 | 1144 |
+------------------+-----------+
4 rows in set (0.00 sec)
mysql> show binary logs;
+------------------+-----------+
| Log_name | File_size |
+------------------+-----------+
| mysql-bin.000001 | 143 |
| mysql-bin.000002 | 261 |
| mysql-bin.000003 | 562 |
| mysql-bin.000004 | 1144 |
+------------------+-----------+
4 rows in set (0.00 sec)
我这⾥有⼀个备份⽂件就是那个创建表的sql语句，位置是mysql-bin.000004 , 4
在这个案例⾥我只⽤cover住mysql-bin.000004这个⽂件。
mysql>show binlog events in 'mysql-bin.000004';
+------------------+------+-------------+-----------+-------------+----------------------------------------------------+
| Log_name | Pos | Event_type | Server_id | End_log_pos | Info |
+------------------+------+-------------+-----------+-------------+----------------------------------------------------+
| mysql-bin.000004 | 4 | Format_desc | 753306 | 120 | Server ver: 5.6.16-64.2-rel64.2-log, Binlog ver: 4 |
| mysql-bin.000004 | 120 | Query | 753306 | 209 | use `wubx`; truncate table tb_wubx |
| mysql-bin.000004 | 209 | Query | 753306 | 281 | BEGIN |
| mysql-bin.000004 | 281 | Table_map | 753306 | 334 | table_id: 91 (wubx.tb_wubx) |
| mysql-bin.000004 | 334 | Write_rows | 753306 | 393 | table_id: 91 flags: STMT_END_F |
| mysql-bin.000004 | 393 | Xid | 753306 | 424 | COMMIT /* xid=1073 */ |
| mysql-bin.000004 | 424 | Query | 753306 | 496 | BEGIN |
| mysql-bin.000004 | 496 | Table_map | 753306 | 549 | table_id: 91 (wubx.tb_wubx) |
| mysql-bin.000004 | 549 | Write_rows | 753306 | 602 | table_id: 91 flags: STMT_END_F |
| mysql-bin.000004 | 602 | Xid | 753306 | 633 | COMMIT /* xid=1074 */ |
| mysql-bin.000004 | 633 | Query | 753306 | 722 | use `wubx`; truncate table tb_wubx |
| mysql-bin.000004 | 722 | Query | 753306 | 794 | BEGIN |
| mysql-bin.000004 | 794 | Table_map | 753306 | 847 | table_id: 92 (wubx.tb_wubx) |
| mysql-bin.000004 | 847 | Write_rows | 753306 | 894 | table_id: 92 flags: STMT_END_F |
| mysql-bin.000004 | 894 | Xid | 753306 | 925 | COMMIT /* xid=1081 */ |
| mysql-bin.000004 | 925 | Query | 753306 | 997 | BEGIN |
| mysql-bin.000004 | 997 | Table_map | 753306 | 1050 | table_id: 92 (wubx.tb_wubx) |
| mysql-bin.000004 | 1050 | Update_rows | 753306 | 1113 | table_id: 92 flags: STMT_END_F |
| mysql-bin.000004 | 1113 | Xid | 753306 | 1144 | COMMIT /* xid=1084 */ |
+------------------+------+-------------+-----------+-------------+----------------------------------------------------+
19 rows in set (0.00 sec)
mysql>show binlog events in 'mysql-bin.000004';
+------------------+------+-------------+-----------+-------------+----------------------------------------------------+
| Log_name | Pos | Event_type | Server_id | End_log_pos | Info |
+------------------+------+-------------+-----------+-------------+----------------------------------------------------+
| mysql-bin.000004 | 4 | Format_desc | 753306 | 120 | Server ver: 5.6.16-64.2-rel64.2-log, Binlog ver: 4 |
| mysql-bin.000004 | 120 | Query | 753306 | 209 | use `wubx`; truncate table tb_wubx |
| mysql-bin.000004 | 209 | Query | 753306 | 281 | BEGIN |
| mysql-bin.000004 | 281 | Table_map | 753306 | 334 | table_id: 91 (wubx.tb_wubx) |
| mysql-bin.000004 | 334 | Write_rows | 753306 | 393 | table_id: 91 flags: STMT_END_F |
| mysql-bin.000004 | 393 | Xid | 753306 | 424 | COMMIT /* xid=1073 */ |
| mysql-bin.000004 | 424 | Query | 753306 | 496 | BEGIN |
| mysql-bin.000004 | 496 | Table_map | 753306 | 549 | table_id: 91 (wubx.tb_wubx) |
| mysql-bin.000004 | 549 | Write_rows | 753306 | 602 | table_id: 91 flags: STMT_END_F |
| mysql-bin.000004 | 602 | Xid | 753306 | 633 | COMMIT /* xid=1074 */ |
| mysql-bin.000004 | 633 | Query | 753306 | 722 | use `wubx`; truncate table tb_wubx |
| mysql-bin.000004 | 722 | Query | 753306 | 794 | BEGIN |
| mysql-bin.000004 | 794 | Table_map | 753306 | 847 | table_id: 92 (wubx.tb_wubx) |
| mysql-bin.000004 | 847 | Write_rows | 753306 | 894 | table_id: 92 flags: STMT_END_F |
| mysql-bin.000004 | 894 | Xid | 753306 | 925 | COMMIT /* xid=1081 */ |
| mysql-bin.000004 | 925 | Query | 753306 | 997 | BEGIN |
| mysql-bin.000004 | 997 | Table_map | 753306 | 1050 | table_id: 92 (wubx.tb_wubx) |
| mysql-bin.000004 | 1050 | Update_rows | 753306 | 1113 | table_id: 92 flags: STMT_END_F |
| mysql-bin.000004 | 1113 | Xid | 753306 | 1144 | COMMIT /* xid=1084 */ |
+------------------+------+-------------+-----------+-------------+----------------------------------------------------+
19 rows in set (0.00 sec)
看到这个表刚开始就发⽣⼀次truncate, 那其实也可以说明我就恢复刚开始那个truncate到后来那个误操作的truncate table的语句之间的数据就是丢失的数据。
这个恢复可以从mysql-bin.000004 pos: 4到mysql-bin.000004 pos: 633 即：
mysqlbinlog --rewrite-db='wubx->re_wubx' --start-position=4 --stop-position=633 mysql-bin.000004 |mysql -S /tmp/mysql.sock re_wubx mysqlbinlog --rewrite-db='wubx->re_wubx' --start-position=4 --stop-position=633 mysql-bin.000004 |mysql -S /tmp/mysql.sock re_wubx
恢复结果如下：
mysql -S /tmp/mysql.sock re_wubx;
mysql>select count(*) from tb_wubx;
+----------+
| count(*) |
+----------+
| 3 |
+----------+
1 row in set (0.0
2 sec)
mysql>select * from tb_wubx;
+----+--------------+
| id | name |
+----+--------------+
| 1 | 张三 |
| 2 | 李四 |
| 3 | 隔壁⽼王 |
+----+--------------+
3 rows in set (0.00 sec)
mysql>insert into tb_wubx(name) select name from wubx.tb_wubx;
Query OK, 1 row affected (0.00 sec)
Records: 1 Duplicates: 0 Warnings: 0
mysql> rename table wubx.tb_wubx to wubx.bak_tb_wubx;
Query OK, 0 rows affected (0.04 sec)
mysql> rename table re_wubx.tb_wubx to wubx.tb_wubx;
Query OK, 0 rows affected (0.03 sec)
mysql> select * from wubx.tb_wubx;
+----+--------------+
| id | name |
+----+--------------+
| 1 | 张三 |
| 2 | 李四 |
| 3 | 隔壁⽼王 |
| 4 | ⽼赵赵 |
+----+--------------+
4 rows in set (0.00 sec)
mysql -S /tmp/mysql.sock re_wubx;
mysql>select count(*) from tb_wubx;
+----------+
| count(*) |
+----------+
| 3 |
+----------+
1 row in set (0.0
2 sec)
mysql>select * from tb_wubx;
+----+--------------+
| id | name |
+----+--------------+
| 1 | 张三 |
| 2 | 李四 |
| 3 | 隔壁⽼王 |
+----+--------------+
3 rows in set (0.00 sec)
mysql>insert into tb_wubx(name) select name from wubx.tb_wubx; Query OK, 1 row affected (0.00 sec)
Records: 1 Duplicates: 0 Warnings: 0
mysql> rename table wubx.tb_wubx to wubx.bak_tb_wubx; Query OK, 0 rows affected (0.04 sec)
mysql> rename table re_wubx.tb_wubx to wubx.tb_wubx;
Query OK, 0 rows affected (0.03 sec)
mysql> select * from wubx.tb_wubx;
+----+--------------+
| id | name |
+----+--------------+
| 1 | 张三 |
| 2 | 李四 |
| 3 | 隔壁⽼王 |
| 4 | ⽼赵赵 |
+----+--------------+
4 rows in set (0.00 sec)
恢复完成。
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