标签归档:MySQL恢复

应用连接错误,初始化mysql数据库恢复

有人在部署一个新网站的时候,写错了配置信息,直接导致原有数据库被清掉,并创建了新库和写入了数据(其实本质就是drop table恢复)
mysql


登录操作系统查看,发现数据库文件在根分区,创建了新库,写入了数据之外,还有几个G的binlog.全部恢复不太可能,最后客户决定需要恢复的2个核心表数据,估计也就几十M的数据.通过os层面进行分析,发现操作系统的反删除恢复无法实现这类数据恢复.最后决定从mysql innodb的的碎片级别记性扫描恢复,通过扫描发现较多碎片
page

然后通过一些思路找出来需要恢复的表对应的page文件,然后对其进行解析恢复出来需要的数据
1

具体技术文章参考:
kettle导致MySQL数据丢失恢复
[MySQL异常恢复]恢复数据字典表讲解
[MySQL异常恢复]mysql drop table 数据恢复
[MySQL异常恢复]使用工具直接抽取MySQL数据字典
MySQL drop database恢复(恢复方法同样适用MySQL drop table,delete,truncate table)

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InnoDB: Database page corruption on disk or a failed file read of page恢复

由于文件系统或者硬件故障导致mysql启动报错InnoDB: Database page corruption on disk or a failed file read of page
mysql-error


使用innodb_force_recovery参数,数据库启动成功,但是部分表查询报错,对于这种情况,是由于ibd文件本身有损坏,通过DISCARD TABLESPACE和IMPORT TABLESPACE也无法解决,只能对ibd文件进行恢复,通过工具直接解析ibd文件恢复其中数据
20230212125347

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MySQL 8.0版本ibd文件恢复

对于单个的ibd文件,大部分情况下可以通过DISCARD TABLESPACE和IMPORT TABLESPACE方式进行恢复

mysql> use test;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> CREATE TABLE `t1` (
    ->   `id` int DEFAULT NULL
    -> ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;
Query OK, 0 rows affected (0.01 sec)
mysql> insert into t1 values(1);
Query OK, 1 row affected (0.02 sec)

mysql> insert into t1 values(2);
Query OK, 1 row affected (0.01 sec)

mysql> insert into t1 values(3);
Query OK, 1 row affected (0.00 sec)

关闭mysql服务,备份mysql中的t1.ibd文件

[root@xifenfei ~]# service mysql stop
Shutting down MySQL..... SUCCESS! 
[root@xifenfei test]# cp t1.ibd  t1_bak

启动mysql服务,并删除并创建新的t1表(表结构相同)

[root@xifenfei test]# service mysql start
Starting MySQL..................... SUCCESS! 


[root@xifenfei test]# mysql -uroot -poracle test
mysql: [Warning] Using a password on the command line interface can be insecure.
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 8.0.31 MySQL Community Server - GPL

Copyright (c) 2000, 2022, Oracle and/or its affiliates.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> drop table t1;
Query OK, 0 rows affected (0.20 sec)


mysql> 
mysql> CREATE TABLE `t1` (
    ->   `id` int DEFAULT NULL
    -> ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;
Query OK, 0 rows affected (0.01 sec)

DISCARD TABLESPACE操作

mysql> ALTER TABLE t1 DISCARD TABLESPACE;
Query OK, 0 rows affected (0.01 sec)

把备份的t1.ibd还原回去并修改权限

[root@xifenfei test]# mv t1_bak t1.ibd
[root@xifenfei test]# ls -ltr
total 112
-rw-r-----. 1 root root 114688 Dec 18 17:24 t1.ibd
[root@xifenfei test]# chown mysql.mysql t1.ibd 

IMPORT TABLESPACE并验证数据

mysql> ALTER TABLE t1 IMPORT TABLESPACE;
Query OK, 0 rows affected, 1 warning (0.24 sec)

mysql> select * from t1;
+------+
| id   |
+------+
|    1 |
|    2 |
|    3 |
+------+
3 rows in set (0.00 sec)

在恢复途中如果遇到表定义不对,或者ibd文件损坏,或者版本不匹配等各种情况,可能在IMPORT TABLESPACE的时候可能出现类似ERROR 1808 (HY000): Schema mismatch (Clustered index validation failed. Because the .cfg file is missing, table definition of the IBD file could be different. Or the data file itself is already corrupted.)错误

mysql>  alter table       `t1` import tablespace;                    
ERROR 1808 (HY000): Schema mismatch (Clustered index validation failed. 
Because the .cfg file is missing, table definition of the IBD file could be different. 
Or the data file itself is already corrupted.)

如果出现此类错误,无法直接通过该方法进行解决,参考frm和ibd文件数据库恢复,使用专业恢复工具进行处理

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