一、场景说明：
很多时候因为 MySQL 数据库不能启动而造成数据无法访问，但应用的数据通常没有丢失，只是系统表空间等其它文件损坏了，或者遇到 MySQL 的 bug。
这个时候如果没有备份，很多人就以为数据丢失了，但实际上大部分时候数据还是有救的。
对于 MyISAM 引擎的表空间，直接把对应的数据文件拷贝到一个新的数据库就行了，数据就可以恢复了。
对于 InnoDB 引擎的数据库表空间可以采用传输表空间的方式把数据救回来.
前提是MySQL开启了参数 innodb_file_per_table = 1 独立表空间文件
当MySQL的数据表空间文件ibdata文件损坏或者是被无修改和删除，导致MySQL服务重启失败。同时MySQL的数据又没有及时备份，此时如何尽可能多的找回MySQL数据呢？？
二、案例演示：
2.1、确认MySQL故障前，库中的每张表有多少记录
for n in `mysql -e "use db_bbs;show tables;"|sed '1d'`;do echo $n; mysql -e "use db_bbs;select count(*) from $n;";done >test.txt确认MySQL故障前，库中一共有多少张表：
一共是39张表：
[root@10-10-127-11 ~]# mysql -e "use db_bbs;show tables;"|sed '1d'|wc -l
392.2、模拟删除ibdata故障：
删除ibdata文件（生产环境禁止这么干）
innodb_force_recovery =6 利用MySQL的强制启动参数来启动此时的MySQL服务，但是已经是无济于事。由于是数据表空间文件ibdata文件被删除了.所以启动不了此时的MySQL服务。
由于此MySQL采用的innodb引擎。而且开启了独立表空间参数 innodb_file_per_table = 1 。所以此时可以采用采用传输表空间的方式把数据救回来。
2.3、找回数据的办法:
首先来创建已经丢失的表结构：
先要在故障的MySQL服务器上 安装 mysql-utilities。
yum -y install mysql-utilities
使用 mysqlfrm 从 .frm 文件里面找回建表语句:
分析一个 .frm 文件生成建表的语句
mysqlfrm --diagnostic
[root@test02 db_bbs]# mysqlfrm --diagnostic /data/mysql/data/db_bbs/t_admin.frm |grep -v "^#"
CREATE TABLE `db_bbs`.`t_admin` (
`f_id` int(4) NOT NULL AUTO_INCREMENT,
`f_type` tinyint(1) NOT NULL,
`f_username` varchar(80) NOT NULL,
`f_password` varchar(80) NOT NULL,
`f_nick_name` varchar(80) NOT NULL,
`f_real_name` varchar(80) NOT NULL,
`f_create_time` bigint(4) NOT NULL,
`f_update_time` bigint(4) NOT NULL,
`f_last_login_time` bigint(4) DEFAULT NULL,
`f_last_login_ip` varchar(80) DEFAULT NULL,
`f_status` tinyint(1) NOT NULL,
PRIMARY KEY `PRIMARY` (`f_id`) USING BTREE
) ENGINE=InnoDB ROW_FORMAT = 2;把全部的建表语句导入到/tmp/create.sql 文件：
[root@test02 ~]# cd /data/mysql/data/db_bbs/
[root@test02 db_bbs]# for n in `ls -l /data/mysql/data/db_bbs/*.frm|awk -F '/' '{print $NF}'|xargs -n 40`;do mysqlfrm --diagnostic $n|grep -v "^#" >>/tmp/create.sql;done 把生产的建表语句导入到新MySQL实例库中:
[root@10-10-127-11 ~]# mysql db_bbs < create.sql
ERROR 1064 (42000) at line 2: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '5' at line 10
原因是获取到的建表sql中包含了ROW_FORMAT = 2 这样的参数导致的###去掉建表语句中的包含ROW_FORMAT = 2, ROW_FORMAT = 5这些字符.重新导入建表语句###
批量替换命令如下:
cat /tmp/create.sql|sed -e 's/ENGINE=InnoDB ROW_FORMAT = 2;/ENGINE=InnoDB ;/g'|grep ROW_FORMAT |uniq -c
cat /tmp/create.sql|sed -e 's/ENGINE=InnoDB ROW_FORMAT = 5;/ENGINE=InnoDB ;/g'|grep ROW_FORMAT |uniq -c
sed -i 's/ENGINE=InnoDB ROW_FORMAT = 2;/ENGINE=InnoDB ;/g' /tmp/create.sql
sed -i 's/ENGINE=InnoDB ROW_FORMAT = 5;/ENGINE=InnoDB ;/g' /tmp/create.sql
cat /tmp/create.sql|grep ROW_FORMAT |uniq -c 导出建表语句到新MySQL实例db_bbs库报错字段太长：
[root@10-10-127-11 ~]# mysql db_bbs -f < create.sql
ERROR 1074 (42000) at line 232: Column length too big for column 'f_content' (max = 16383); use BLOB or TEXT instead
ERROR 1074 (42000) at line 299: Column length too big for column 'f_desc' (max = 16383); use BLOB or TEXT instead
ERROR 1074 (42000) at line 365: Column length too big for column 'f_body_image' (max = 16383); use BLOB or TEXT instead
ERROR 1074 (42000) at line 406: Column length too big for column 'f_content' (max = 16383); use BLOB or TEXT instead
ERROR 1074 (42000) at line 433: Column length too big for column 'f_summary' (max = 16383); use BLOB or TEXT instead修改完字段长度类型，重新导入建表sql到全新的MySQL库中
[root@10-10-127-11 ~]# mysql db_bbs -f < create.sql
[root@10-10-127-11 ~]#
[root@10-10-127-11 ~]#
[root@10-10-127-11 ~]# mysql -e "use db_bbs;show tables;"|sed '1d'|wc -l
39###将新建的MySQL实例的 没有包括数据的 .ibd 文件抛弃掉，然后再导入故障数据库的.idb文件###
抛弃掉新建库的数据.ibd文件：
mysql -e "show tables from db_bbs" | grep -v Tables_in_db_bbs| while read a; do mysql -e "ALTER TABLE db_bbs.$a DISCARD TABLESPACE" ;done[root@10-10-127-11 db_bbs]# ll *.ibd|wc -l
39
[root@10-10-127-11 db_bbs]# mysql -e "show tables from db_bbs" | grep -v Tables_in_db_bbs| while read a; do mysql -e "ALTER TABLE db_bbs.$a DISCARD TABLESPACE" ;done
[root@10-10-127-11 db_bbs]# ll *.ibd|wc -l
ls: cannot access *.ibd: No such file or directory0
*可以看到所有的 .idb 文件都已经被抛弃了。然后把旧的有数据的 .ibd 文件拷贝到这个新MySQL实例的 ./data/db_bbs/ 目录下面，别忘了把属主改过来：chown mysql. ，再把这些数据文件 import 到数据库中**。
[root@test02 db_bbs]# scp *.ibd root@10.10.127.11:/data/mysql/data/db_bbs/
root@10.10.127.11's password:
browse_record.ibd 100% 100MB 50.0MB/s 00:02
t_admin.ibd
........
........[root@10-10-127-11 db_bbs]# ll *.ibd|wc -l
39
[root@10-10-127-11 db_bbs]# ll *.ibd
-rw-r----- 1 root root 104857600 Mar 14 21:56 browse_record.ibd
-rw-r----- 1 root root 98304 Mar 14 21:56 t_admin.ibd
-rw-r----- 1 root root 98304 Mar 14 21:56 t_anonymous_code.ibd
-rw-r----- 1 root root 98304 Mar 14 21:56 t_apply.ibd
-rw-r----- 1 root root 9437184 Mar 14 21:56 t_attach.ibd
-rw-r----- 1 root root 147456 Mar 14 21:56 t_banner.ibd
-rw-r----- 1 root root 163840 Mar 14 21:56 t_banner_log.ibd
-rw-r----- 1 root root 114688 Mar 14 21:56 t_black_ip.ibd
-rw-r----- 1 root root 98304 Mar 14 21:56 t_black_user.ibd
-rw-r----- 1 root root 98304 Mar 14 21:56 t_block_userbaseinfo.ibd
-rw-r----- 1 root root 98304 Mar 14 21:56 t_collect.ibd
-rw-r----- 1 root root 98304 Mar 14 21:56 t_country_code.ibd
-rw-r----- 1 root root 163840 Mar 14 21:56 t_ct_goods.ibd
-rw-r----- 1 root root 131072 Mar 14 21:56 t_ct_goods_record.ibd
-rw-r----- 1 root root 9437184 Mar 14 21:56 t_ct_integral.ibd
-rw-r----- 1 root root 46137344 Mar 14 21:56 t_ct_integral_record.ibd
-rw-r----- 1 root root 27262976 Mar 14 21:56 t_ct_news.ibd
-rw-r----- 1 root root 9437184 Mar 14 21:56 t_ct_order.ibd
-rw-r----- 1 root root 98304 Mar 14 21:56 t_feedback.ibd
-rw-r----- 1 root root 98304 Mar 14 21:56 t_lexicon.ibd
-rw-r----- 1 root root 327680 Mar 14 21:56 t_logs.ibd
-rw-r----- 1 root root 98304 Mar 14 21:56 t_manage.ibd
-rw-r----- 1 root root 98304 Mar 14 21:56 t_module.ibd
-rw-r----- 1 root root 9437184 Mar 14 21:56 t_post_extend.ibd
-rw-r----- 1 root root 12582912 Mar 14 21:56 t_post.ibd
-rw-r----- 1 root root 98304 Mar 14 21:56 t_post_video.ibd
-rw-r----- 1 root root 98304 Mar 14 21:56 t_realtime_message.ibd
-rw-r----- 1 root root 98304 Mar 14 21:56 t_recommend.ibd
-rw-r----- 1 root root 46137344 Mar 14 21:56 t_reply.ibd
-rw-r----- 1 root root 98304 Mar 14 21:56 t_reward.ibd
-rw-r----- 1 root root 196608 Mar 14 21:56 t_sensitive_word.ibd
-rw-r----- 1 root root 98304 Mar 14 21:56 t_system_message.ibd
-rw-r----- 1 root root 9437184 Mar 14 21:56 t_userbaseinfo.ibd
-rw-r----- 1 root root 344064 Mar 14 21:56 t_userextendinfo.ibd
-rw-r----- 1 root root 12582912 Mar 14 21:56 t_user_health.ibd
-rw-r----- 1 root root 98304 Mar 14 21:56 t_user_message.ibd
-rw-r----- 1 root root 442368 Mar 14 21:56 t_user_read_module_log.ibd
-rw-r----- 1 root root 17825792 Mar 14 21:56 t_viewpoint.ibd
-rw-r----- 1 root root 114688 Mar 14 21:56 t_white_ip.ibd
[root@10-10-127-11 db_bbs]# chown mysql.mysql *.ibd
mysql -e "show tables from db_bbs" | grep -v Tables_in_db_bbs| while read a; do mysql -e "ALTER TABLE db_bbs.$a import TABLESPACE" ;done导入每个表的表空间时，出现个别表报错：
[root@10-10-127-11 db_bbs]# mysql -e "show tables from db_bbs" | grep -v Tables_in_db_bbs| while read a; do mysql -e "ALTER TABLE db_bbs.$a import TABLESPACE" ;done
ERROR 1808 (HY000) at line 1: Schema mismatch (Table has ROW_TYPE_DYNAMIC row format, .ibd file has ROW_TYPE_COMPACT row format.)校验表文件，发现只有browse_record表导入独立表表空间时报错导致此表恢复数据失败
[root@10-10-127-11 db_bbs]# mysqlcheck -c db_bbs
db_bbs.browse_record
Warning : InnoDB: Tablespace has been discarded for table 'browse_record'
Error : Tablespace has been discarded for table 'browse_record'
error : Corrupt
db_bbs.t_admin OK
db_bbs.t_anonymous_code OK
db_bbs.t_apply OK
db_bbs.t_attach OK
db_bbs.t_banner OK
db_bbs.t_banner_log OK
db_bbs.t_black_ip OK
db_bbs.t_black_user OK
db_bbs.t_block_userbaseinfo OK
db_bbs.t_collect OK
db_bbs.t_country_code OK
db_bbs.t_ct_goods OK
db_bbs.t_ct_goods_record OK
db_bbs.t_ct_integral OK
db_bbs.t_ct_integral_record OK
db_bbs.t_ct_news OK
db_bbs.t_ct_order OK
db_bbs.t_feedback OK
db_bbs.t_lexicon OK
db_bbs.t_logs OK
db_bbs.t_manage OK
db_bbs.t_module OK
db_bbs.t_post OK
db_bbs.t_post_extend OK
db_bbs.t_post_video OK
db_bbs.t_realtime_message OK
db_bbs.t_recommend OK
db_bbs.t_reply OK
db_bbs.t_reward OK
db_bbs.t_sensitive_word OK
db_bbs.t_system_message OK
db_bbs.t_user_health OK
db_bbs.t_user_message OK
db_bbs.t_user_read_module_log OK
db_bbs.t_userbaseinfo OK
db_bbs.t_userextendinfo OK
db_bbs.t_viewpoint OK
db_bbs.t_white_ip OK上面的browse_record 表恢复失败 报错解决办法如下：
参考：https://blog.csdn.net/weixin_30607659/article/details/94987901
删除导入到新MySQL实例的表browse_record，然后执行下面的建表语句，新建browse_record表：
CREATE TABLE `browse_record` (
`id` int(4) unsigned NOT NULL AUTO_INCREMENT,
`post_id` int(4) unsigned NOT NULL,
`user_id` int(4) unsigned NOT NULL,
`status` tinyint(1) unsigned NOT NULL,
`update_time` bigint(4) unsigned NOT NULL,
`create_time` bigint(4) unsigned NOT NULL,
PRIMARY KEY (`id`) USING BTREE,
KEY `browse` (`post_id`,`user_id`) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 row_format=compact;提示：如果在新MySQL实例单独删除表browse_record，删除失败的话，那就直接drop掉新MySQL实例上的db_bbs库，重新导入db_bbs所有表的建表语句，然后再执行下面的命令：
mysql -e "show tables from db_bbs" | grep -v Tables_in_db_bbs| while read a; do mysql -e "ALTER TABLE db_bbs.$a DISCARD TABLESPACE" ;done重新导入表空间到新实例MySQL中:
[root@10-10-127-11 db_bbs]# mysql -e "show tables from db_bbs" | grep -v Tables_in_db_bbs| while read a; do mysql -e "ALTER TABLE db_bbs.$a import TABLESPACE" ;done
[root@10-10-127-11 db_bbs]# 到此处数据修复完成
校验MySQL db_bbs库中的表：
[root@10-10-127-11 db_bbs]# mysqlcheck -c db_bbs
db_bbs.browse_record OK
db_bbs.t_admin OK
db_bbs.t_anonymous_code OK
db_bbs.t_apply OK
db_bbs.t_attach OK
db_bbs.t_banner OK
db_bbs.t_banner_log OK
db_bbs.t_black_ip OK
db_bbs.t_black_user OK
db_bbs.t_block_userbaseinfo OK
db_bbs.t_collect OK
db_bbs.t_country_code OK
db_bbs.t_ct_goods OK
db_bbs.t_ct_goods_record OK
db_bbs.t_ct_integral OK
db_bbs.t_ct_integral_record OK
db_bbs.t_ct_news OK
db_bbs.t_ct_order OK
db_bbs.t_feedback OK
db_bbs.t_lexicon OK
db_bbs.t_logs OK
db_bbs.t_manage OK
db_bbs.t_module OK
db_bbs.t_post OK
db_bbs.t_post_extend OK
db_bbs.t_post_video OK
db_bbs.t_realtime_message OK
db_bbs.t_recommend OK
db_bbs.t_reply OK
db_bbs.t_reward OK
db_bbs.t_sensitive_word OK
db_bbs.t_system_message OK
db_bbs.t_user_health OK
db_bbs.t_user_message OK
db_bbs.t_user_read_module_log OK
db_bbs.t_userbaseinfo OK
db_bbs.t_userextendinfo OK
db_bbs.t_viewpoint OK
db_bbs.t_white_ip OK2.4、获取导入到新MySQL实例db_bbs库中表记录和和原来的库test.txt表记录文件对比
[root@10-10-127-11 ~]# for n in `mysql -e "use db_bbs;show tables;"|sed '1d'`;do echo $n; mysql -e "use db_bbs;select count(*) from $n;";done >test.txt11
和原来的库test.txt表记录文件对比。
[root@test02 ~]# vimdiff test.txt11 test.txt
表记录完全一致到此处MySQL的数据修复完毕
参考资料：
https://mp.weixin.qq.com/s/r3KTPsFay292JnO0lgTLUg
https://www.cnblogs.com/jiangxu67/p/4744283.html
https://blog.csdn.net/Sonny_alice/article/details/80198200
https://www.cnblogs.com/jiangxu67/p/4744283.html