无备份mysql删除表后恢复

mysql从5.6.17开始自动设置innodb_file_per_table为on，每个表设置单独表空间，数据不是集中存放在ibdata1里。下面测试下无备份后drop表后的恢复。

前奏生成数据字典https://www.cnblogs.com/omsql/p/9253234.html

删除表前的准备
mysql>  SHOW VARIABLES LIKE 'innodb_file_per_table';
+-----------------------+-------+
| Variable_name         | Value |
+-----------------------+-------+
| innodb_file_per_table | ON    |
+-----------------------+-------+
1 row in set (0.00 sec)

mysql> show create table tb \G
*************************** 1. row ***************************
       Table: tb
Create Table: CREATE TABLE `tb` (
  `id` int(11) NOT NULL,
  `name` varchar(16) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

[root@redis01 tmp]# cd /data/mysql/ht/
[root@redis01 ht]# ls
db.opt  person.frm  person.ibd  shirt.frm  shirt.ibd  tb.frm  tb.ibd

mysql> select * from tb;
+----+-------+
| id | name  |
+----+-------+
|  1 | zhou  |
|  2 | 430   |
|  3 | YYF   |
|  4 | ChuaN |
|  5 | Faith |
|  6 | zhou  |
|  7 | 430   |
|  8 | YYF   |
|  9 | ChuaN |
| 10 | Faith |
| 11 | zhou  |
| 12 | 430   |
| 13 | YYF   |
| 14 | ChuaN |
| 15 | Faith |
+----+-------+
15 rows in set (0.00 sec)

mysql> checksum table tb;
+-------+------------+
| Table | Checksum   |
+-------+------------+
| ht.tb | 1499182360 |
+-------+------------+
1 row in set (0.00 sec)

mysql> drop table tb;
Query OK, 0 rows affected (0.11 sec)
删除表后相对表的表空间文件也删除
[root@redis01 ht]# ls
db.opt  person.frm  person.ibd  shirt.frm  shirt.ibd  tb.frm  tb.ibd
[root@redis01 ht]# ls
db.opt  person.frm  person.ibd  shirt.frm  shirt.ibd
失误操作后建议关闭mysql，避免空间被占用
mysqladmin -u root -p shutdown

[root@redis01 data]# df -k
Filesystem           1K-blocks     Used Available Use% Mounted on
/dev/mapper/vg_redis01-lv_root
                      20830728 10397672   9459576  53% /
tmpfs                  2022820       72   2022748   1% /dev/shm
/dev/sda1               487652    85768    372188  19% /boot
/dev/mapper/vg_mysql-lv_mysql01
                        303788   114540    189248  38% /data

从磁盘里查找，分别得到每个页文件
stream_parser
stream_parser 是分析 ibdata 文件（或者挂载的磁盘），得到每一个数据页的
./stream_parser -f /dev/mapper/vg_mysql-lv_mysql01  -t 303788k
查看页文件里的具体数据
c_parser 其实是按照 innodb 存储数据的格式来分析哪些是我们需要的数据本身，所以页上的数据可以分为两类：1. 用户数据 2. 元数据。而元数据的功能其实并不相同，有些损坏无伤大雅，有些损坏却可能导致整个页无法恢复。
./c_parser -6f pages-vg_mysql-lv_mysql01/FIL_PAGE_INDEX/0000000000000041.page -t tb.sql |  head -5

生成建表语句
 [root@redis01 undrop-for-innodb]# cat tb.sql
CREATE TABLE `tb` (
  `id` int(11) NOT NULL,
  `name` varchar(16) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

查看恢复出来的数据
 [root@redis01 undrop-for-innodb]# ./c_parser -6f pages-vg_mysql-lv_mysql01/FIL_PAGE_INDEX/0000000000000041.page -t tb.sql |  head -6
-- Page id: 3, Format: COMPACT, Records list: Valid, Expected records: (5 5)
000000000507	A70000011B0110	tb	1	"zhou"
000000000507	A70000011B011C	tb	2	"430"
000000000507	A70000011B0128	tb	3	"YYF"
000000000507	A70000011B0134	tb	4	"ChuaN"
000000000507	A70000011B0140	tb	5	"Faith"

生成脚本
./c_parser -6f pages-vg_mysql-lv_mysql01/FIL_PAGE_INDEX/0000000000000041.page -t tb.sql  > dumps/default/tb 2> dumps/default/tb_TABLES.sql

先建表在导入恢复出来的数据
mysql -u root -p ht < tb.sql
mysql -u root -p ht < dumps/default/tb_TABLES.sql

mysql> select * from ht.tb;
Empty set (0.00 sec)

mysql> select * from ht.tb;
+----+-------+
| id | name  |
+----+-------+
|  1 | zhou  |
|  2 | 430   |
|  3 | YYF   |
|  4 | ChuaN |
|  5 | Faith |
|  6 | zhou  |
|  7 | 430   |
|  8 | YYF   |
|  9 | ChuaN |
| 10 | Faith |
| 11 | zhou  |
| 12 | 430   |
| 13 | YYF   |
| 14 | ChuaN |
| 15 | Faith |
+----+-------+
15 rows in set (0.00 sec)