How To:利用frm和idb文件进行数据恢复.txt

在另外一个机器上准备测试数据，并传输到dbadb05机器的/mysql/backup/reco/位置下。
开始尝试恢复数据
一、使用mysqlfrm获取表结构信息及DDL语句。

[mysql@dbadb05 reco]$ ll
total
-rw-r-----  mysql mysql  Aug  : t.frm
-rw-r-----  mysql mysql  Aug  : t.ibd
[mysql@dbadb05 reco]$ mysqlfrm t.frm --basedir=/mysql/mysql --port= --show-stats --verbose
# Starting the spawned server on port  ... done.
# Reading .frm files
#
# Reading the t.frm file.
#
# CREATE statement for t.frm:
#

CREATE TABLE `t` (
`a` int() DEFAULT NULL,
`b` int() DEFAULT NULL,
`c` varchar() DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4

# File Statistics:
# Last Modified : Mon Aug  ::
# Creation Time : Mon Aug  ::
# Last Accessed : Mon Aug  ::
# Mode :
# Size : 

# Table Statistics:
# Engine : HEAP
# frm Version :
# MySQL Version : 5.7.
# frm File_Version :
# IO_SIZE :
# Def Partition Engine : None

#...done.

二、使用第一步中恢复的DDL语句创建表，并discard tablespace

mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| syk |
| sys |
+--------------------+
5 rows in set (0.00 sec)

mysql> create database reco;
Query OK, 1 row affected (0.00 sec)

mysql> use reco;
Database changed
mysql> CREATE TABLE `t` (
-> `a` int(11) DEFAULT NULL,
-> `b` int(11) DEFAULT NULL,
-> `c` varchar(10) DEFAULT NULL
-> ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
Query OK, 0 rows affected (0.02 sec)

mysql> alter table t discard tablespace;
Query OK, 0 rows affected (0.02 sec)

三、拷贝ibd文件到对应路径，并import tablespace

[mysql@dbadb05 reco]$ ll
total 16
-rw-r----- 1 mysql mysql 67 Aug 6 15:46 db.opt
-rw-r----- 1 mysql mysql 8602 Aug 6 15:47 t.frm
[mysql@dbadb05 reco]$ cp /mysql/backup/reco/t.ibd .
[mysql@dbadb05 reco]$ ls -lrt
total 112
-rw-r----- 1 mysql mysql 67 Aug 6 15:46 db.opt
-rw-r----- 1 mysql mysql 8602 Aug 6 15:47 t.frm
-rw-r----- 1 mysql mysql 98304 Aug 6 15:49 t.ibd

[mysql@dbadb05 reco]$ mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.22-log MySQL Community Server (GPL)

Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.

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> use reco;
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, 1 warning
mysql> show warnings\G;
*************************** 1. row ***************************
Level: Warning
Code: 1287
Message: 'COM_FIELD_LIST' is deprecated and will be removed in a future release. Please use SHOW COLUMNS FROM statement instead
*************************** 2. row ***************************
Level: Warning
Code: 1814
Message: InnoDB: Tablespace has been discarded for table 't'
2 rows in set (0.00 sec)

ERROR:
No query specified

mysql> alter table t import tablespace;
Query OK, 0 rows affected, 1 warning (0.03 sec)

mysql> show warnings\G;
*************************** 1. row ***************************
Level: Warning
Code: 1810
Message: InnoDB: IO Read error: (2, No such file or directory) Error opening './reco/t.cfg', will attempt to import without schema verification
1 row in set (0.00 sec)

ERROR:
No query specified

四、查看表中的数据

mysql> select * from t;
+------+------+------+
| a | b | c |
+------+------+------+
| 1 | 1 | a |
+------+------+------+
1 row in set (0.00 sec)

五、没有mysqlfrm工具，恢复DDL的方法
仅供mysqlfrm工具时，尝试性恢复。
1、随意建立一个数据库和一张表

mysql> create database reco;
Query OK, 1 row affected (0.01 sec)

mysql> use reco;
Database changed
mysql> create table t( c1 int);
Query OK, 0 rows affected (0.03 sec)

mysql> show create table t\G;
*************************** 1. row ***************************
Table: t
Create Table: CREATE TABLE `t` (
`c1` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4
1 row in set (0.00 sec)

ERROR:
No query specified

2、拷贝需要恢复的frm文件到对应位置，并覆盖

mysql> system cp /mysql/backup/reco/t.frm /mysql/data/reco/t.frm
mysql> show create table t\G;
*************************** 1. row ***************************
Table: t
Create Table: CREATE TABLE `t` (
`c1` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4
1 row in set (0.00 sec)

ERROR:
No query specified

mysql> flush table t;
Query OK, 0 rows affected (0.01 sec)

mysql> show create table t\G;
ERROR 1146 (42S02): Table 'reco.t' doesn't exist
ERROR:
No query specified

3、此时报错，表报错，意料中的事情，查看mysql的错误日志
[Warning] InnoDB: Table reco/t contains user defined columns in InnoDB, but columns in MySQL. Please check INFORMATION_SCHEMA.INNODB_SYS_COLUMNS and http://dev.mysql.com/doc/refman/5.7/en/innodb-troubleshooting.html for how to resolve the issue.

注意到日志中的信息，我们定义了1个列，但是MySQL中有3列。

4、删除原来的表，建立相同个数的列，名称和类型随意。

mysql> drop table t;
Query OK, 0 rows affected (0.02 sec)

mysql> create table t(c1 int,c2 int, c3 int);
Query OK, 0 rows affected (0.02 sec)

mysql> show create table t\G;
*************************** 1. row ***************************
Table: t
Create Table: CREATE TABLE `t` (
`c1` int(11) DEFAULT NULL,
`c2` int(11) DEFAULT NULL,
`c3` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4
1 row in set (0.00 sec)

ERROR:
No query specified

5、重复第二步，覆盖frm文件，就可以获得定义语句，结果与第一部分得出的一样

mysql> system cp /mysql/backup/reco/t.frm /mysql/data/reco/t.frm
mysql> show create table t\G;
*************************** 1. row ***************************
Table: t
Create Table: CREATE TABLE `t` (
`c1` int(11) DEFAULT NULL,
`c2` int(11) DEFAULT NULL,
`c3` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4
1 row in set (0.00 sec)

ERROR:
No query specified

mysql> flush table t;
Query OK, 0 rows affected (0.01 sec)

mysql> show create table t\G;
*************************** 1. row ***************************
Table: t
Create Table: CREATE TABLE `t` (
`a` int(11) DEFAULT NULL,
`b` int(11) DEFAULT NULL,
`c` varchar(10) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4
1 row in set (0.01 sec)

ERROR:
No query specified

六、安全性问题
MySQL的这个设计，方便了恢复。但是有着严重的安全隐患，一旦这两个文件被非法获取，所有数据将被泄露。