mysql恢复之delete 忘加where条件误删除恢复(binglog格式必须是ROW)

(一)恢复的前提条件就是开启了二进制日志和格式为行格式,二个条件缺一不行!

mysql> show variables like "%log_bin%";

+---------------------------------+---------------------------------------+
| Variable_name                   | Value                                 |
+---------------------------------+---------------------------------------+
| log_bin                         | ON                                    |
| log_bin_basename                | /usr/local/mysql/data/mysql_bin       |
| log_bin_index                   | /usr/local/mysql/data/mysql_bin.index |
| log_bin_trust_function_creators | OFF                                   |
| log_bin_use_v1_row_events       | OFF                                   |
| sql_log_bin                     | ON                                    |

+---------------------------------+---------------------------------------+


mysql> show variables like "%binlog_format%";
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| binlog_format | ROW   |
+---------------+-------+


(二)准备测试数据

mysql> create  table testdb.person_t(id int,name varchar(10),address varchar(10));
Query OK, 0 rows affected (0.03 sec)


mysql> insert into testdb.person_t values(1,'anzhen','nanning'),(2,'liming','beijng'),(3,'xiaohon','gzhou'),(4,'sfds','nhui');
Query OK, 4 rows affected (0.05 sec)
Records: 4  Duplicates: 0  Warnings: 0

mysql> select * from testdb.person_t;
+------+---------+---------+
| id   | name    | address |
+------+---------+---------+
|    1 | anzhen  | nanning |
|    2 | liming  | beijng  |
|    3 | xiaohon | gzhou   |
|    4 | sfds    | nhui    |
+------+---------+---------+
4 rows in set (0.00 sec)


(三)误delete操作,没有加where条件

mysql> delete from testdb.person_t;
Query OK, 4 rows affected (0.01 sec)


mysql> commit;
Query OK, 0 rows affected (0.00 sec)


mysql> select * from testdb.person_t;
Empty set (0.00 sec)

(四)首先要确定delete误操作写进了那个binlog二进制日志文件里面,然后这个二进制日志从中恢复相关行操作。因为启用的是row行格式,所有的每条记录

的修改等等操作都会记录在二进制日志里面。

如果没有其他人flush logs的话,误操作就记录在mysql_bin.000401这个二进制日志文件中。如果有他人flush logs。就往以上找。直到发现误操作的记录。

开始恢复,在线上的话,应该比较复杂,要先进行锁表,以免数据再次被污染。(锁表,查看正在写哪个二进制日志)

mysql> lock table testdb.person_t read;
Query OK, 0 rows affected (0.00 sec)

mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql_bin.000401 |     1045 |              |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

mysql> flush logs;

(五)查看binlog的相关信息 

查看MySQL的安装目录:

mysql> show variables like "%basedir%";
+---------------+-------------------+
| Variable_name | Value             |
+---------------+-------------------+
| basedir       | /usr/local/mysql/ |
+---------------+-------------------+
1 row in set (0.00 sec)

查看binlog的日志目录和格式:

mysql> show variables like "%log_bin%";
+---------------------------------+---------------------------------------+
| Variable_name                   | Value                                 |
+---------------------------------+---------------------------------------+
| log_bin                         | ON                                    |
| log_bin_basename                | /usr/local/mysql/data/mysql_bin       |
| log_bin_index                   | /usr/local/mysql/data/mysql_bin.index |
| log_bin_trust_function_creators | OFF                                   |
| log_bin_use_v1_row_events       | OFF                                   |
| sql_log_bin                     | ON                                    |
+---------------------------------+---------------------------------------+
6 rows in set (0.01 sec)


(六)新建一个session。查看mysqlbinlog里面delete操作的格式,因为版本不一样,可能格式不一样。

/usr/local/mysql/bin/mysqlbinlog --no-defaults --base64-output=decode-rows  -v -v /usr/local/mysql/data/mysql_bin.000401 > /tmp/info.txt

[root@localhost104 mysql]# cat /tmp/info.txt | grep delete
[root@localhost104 mysql]# cat /tmp/info.txt | grep DELETE
### DELETE FROM `testdb`.`person_t`
### DELETE FROM `testdb`.`person_t`
### DELETE FROM `testdb`.`person_t`
### DELETE FROM `testdb`.`person_t`


(七)在binglog中去查找相关误delete操作的记录,delete from testdb.person_t操作删除了四行数据mysql_bin.000401,建议写全部目录。

[root@localhost104 mysql]# /usr/local/mysql/bin/mysqlbinlog --no-defaults --base64-output=decode-rows  -v -v /usr/local/mysql/data/mysql_bin.000401| sed -n '/### DELETE FROM `testdb`.`person_t`/,/COMMIT/p' > /tmp/delete.txt 
[root@localhost104 mysql]# 
[root@localhost104 mysql]# 
[root@localhost104 mysql]# cat  /tmp/delete.txt
### DELETE FROM `testdb`.`person_t`
### WHERE
###   @1=1 /* INT meta=0 nullable=1 is_null=0 */
###   @2='anzhen' /* VARSTRING(10) meta=10 nullable=1 is_null=0 */
###   @3='nanning' /* VARSTRING(10) meta=10 nullable=1 is_null=0 */
### DELETE FROM `testdb`.`person_t`
### WHERE
###   @1=2 /* INT meta=0 nullable=1 is_null=0 */
###   @2='liming' /* VARSTRING(10) meta=10 nullable=1 is_null=0 */
###   @3='beijng' /* VARSTRING(10) meta=10 nullable=1 is_null=0 */
### DELETE FROM `testdb`.`person_t`
### WHERE
###   @1=3 /* INT meta=0 nullable=1 is_null=0 */
###   @2='xiaohon' /* VARSTRING(10) meta=10 nullable=1 is_null=0 */
###   @3='gzhou' /* VARSTRING(10) meta=10 nullable=1 is_null=0 */
### DELETE FROM `testdb`.`person_t`
### WHERE
###   @1=4 /* INT meta=0 nullable=1 is_null=0 */
###   @2='sfds' /* VARSTRING(10) meta=10 nullable=1 is_null=0 */
###   @3='nhui' /* VARSTRING(10) meta=10 nullable=1 is_null=0 */
# at 1014
#170723 11:35:54 server id 10  end_log_pos 1045 CRC32 0x731dc552        Xid = 113
COMMIT/*!*/;

(8)把delete操作还原成insert操作。这样可以把数据找回来。@1,@2,@3分别表示第1个字段,第2个字段,第3个字段。误删的表有3个字段,所

以就配置cat /tmp/delete.txt | sed -n '/###/p' | sed 's/### //g;s/\/\*.*/,/g;s/DELETE FROM/INSERT INTO/g;s/WHERE/SELECT/g;' | sed -r 's/(@3.*),/\1;/g' | sed 's/@[1-3]=//g' > /tmp/person_t.sql,如果有17个字段,就配置为cat /tmp/delete.txt | sed -n '/###/p' | sed 's/### //g;s/\/\*.*/,/g;s/DELETE FROM/INSERT INTO/g;s/WHERE/SELECT/g;' | sed -r 's/(@17.*),/\1;/g' | sed 's/@[1-17]=//g' > /tmp/person_t.sql就可以了。只需要改数字。

 

[root@localhost104 mysql]# cat /tmp/delete.txt | sed -n '/###/p' | sed 's/### //g;s/\/\*.*/,/g;s/DELETE FROM/INSERT INTO/g;s/WHERE/SELECT/g;' | sed -r 's/(@3.*),/\1;/g' | sed 's/@[1-3]=//g' > /tmp/person_t.sql

[root@localhost104 mysql]# cat   /tmp/person_t.sql
INSERT INTO `testdb`.`person_t`
SELECT
  1 ,
  'anzhen' ,
  'nanning' ;
INSERT INTO `testdb`.`person_t`
SELECT
  2 ,
  'liming' ,
  'beijng' ;
INSERT INTO `testdb`.`person_t`
SELECT
  3 ,
  'xiaohon' ,
  'gzhou' ;
INSERT INTO `testdb`.`person_t`
SELECT
  4 ,
  'sfds' ,
  'nhui' ;

查看一下数据是否是要恢复的数据,如果是的话,就可以进行恢复操作。

在进行lock表的mysql客户端里面执行。

 mysql>unlock tables;  source /tmp/person_t.sql;

Query OK, 1 row affected (0.03 sec)
Records: 1  Duplicates: 0  Warnings: 0


Query OK, 1 row affected (0.02 sec)
Records: 1  Duplicates: 0  Warnings: 0


Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0


Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0


(9)验证数据是否恢复完成!

mysql> select * from testdb.person_t;
+------+---------+---------+
| id   | name    | address |
+------+---------+---------+
|    1 | anzhen  | nanning |
|    2 | liming  | beijng  |
|    3 | xiaohon | gzhou   |
|    4 | sfds    | nhui    |
+------+---------+---------+
5 rows in set (0.00 sec)

恢复成功!

可以看见数据已经完全恢复,这种方法的优点是快速,方便。前提是在误操作之前开启了二进制日志和行格式。

到这里数据就完整回来了。将binglog格式设置为row有利有弊,好处是记录了每一行的实际变化,在主从复制时也不容易出问题。但是由于记录每行的变化,会占用大量磁盘,主从复制时带宽占用会有所消耗。到底是使用row还是mixed,需要在实际工作中自己去衡量,但从整体上来说,binglog的格式设置为row,都是不二的选择。

总结:

所以在数据库操作的过程中我们需要格外小心,当然开发那边我们需要做好权限的控制,不过有一个参数可以解决我们的问题,让我们不用担心类似的问题发生:

在[mysql]段落开启这个参数:

safe-updates

这样当我们在做DML操作时忘记加where条件时,mysqld服务器是不会执行操作的:

复制代码
mysql> select *  from t1;
+----+------------------+
| id | name             |
+----+------------------+
|  1 | yayun            |
|  2 | atlas            |
|  3 | mysql            |
|  6 | good yayun heheh |
+----+------------------+
4 rows in set (0.00 sec)

mysql> delete from t1;
ERROR 1175 (HY000): You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
mysql> 


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