分类目录归档：MySQL恢复

MyISAM表delete记录恢复

发表于 2022 年 11 月 25 日 由 惜分飞

有客户delete删除了myisam表中的部分数据,本来表中4-5w条记录,删除之后值剩余几十条,希望对其进行恢复（该库没有开启binlog）

mysql> select count(1) from db_bet;
+----------+
| count(1) |
+----------+
|       46 |
+----------+
1 row in set (0.00 sec)

通过分析.MYD文件确认数据依旧在文件中
myisam-delete-recovery

通过工具对其删除操作分析,找到记录如下
20221125175222
对其记录入库确认

mysql> select count(1) from db_bet_deleted;
+----------+
| count(1) |
+----------+
|    40158 |
+----------+
1 row in set (0.10 sec)
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mysql ibd文件反删除恢复之后异常处理

发表于 2022 年 7 月 15 日 由 惜分飞

有客户因为误操作删除了mysql的datadir目录,并且mysql数据库已经关闭(如果没有关闭可以采用类似方法:mysql 数据库目录被删除恢复),由于无法通过该方法直接处理,首先尝试文件系统层面进行恢复
20220715215237

虽然可以看到相关的数据文件(最大的一个表的ibd文件100多G),通过查看该ibd文件发现几乎全部为0
20220715215439
基于这种情况,无法通过文件系统层面进行恢复，只能考虑从mysql block层面进行恢复,参考类似恢复:又一起mysql rm删除数据库目录事故处理方法,实现绝大多数数据恢复
20220715215058
再次提醒对于mysql数据库也需要考虑好安全备份方案,谁都不能保证人永远不误操作,不能保证硬件永远不出故障.

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InnoDB: Cannot open table db/tab from the internal data dictionary of InnoDB though the .frm file for the table exists

发表于 2022 年 7 月 9 日 由 惜分飞

有客户找到我说mysql无法正常使用报错如下（库名.表名 doesn’t exist）:
mysql-doesnot-exist

客户确认表的frm和ibd文件均存在.通过检查mysql日志,发现大量类似异常
mysql-1
而且情况一样ibd和frm文件均存在,系统日志中提示：
2022-07-08T08:37:57.935514Z 1423 [Warning] InnoDB: Cannot open table 库名/表名 from the internal data dictionary of InnoDB though the .frm file for the table exists. Please refer to http://dev.mysql.com/doc/refman/5.7/en/innodb-troubleshooting.html for how to resolve the issue.
根据对mysql的认知,出现此类问题,很可能是mysql的ibdata文件出了问题,对日志进行分析,发现类似记录

2022-07-08T04:11:27.413455Z 0 [Note] /www/server/mysql/bin/mysqld (mysqld 5.7.34-log) starting as process 2144 ...
2022-07-08T04:11:27.495536Z 0 [Note] InnoDB: PUNCH HOLE support available
2022-07-08T04:11:27.495559Z 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2022-07-08T04:11:27.495562Z 0 [Note] InnoDB: Uses event mutexes
2022-07-08T04:11:27.495565Z 0 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier
2022-07-08T04:11:27.495568Z 0 [Note] InnoDB: Compressed tables use zlib 1.2.11
2022-07-08T04:11:27.495571Z 0 [Note] InnoDB: Using Linux native AIO
2022-07-08T04:11:27.496130Z 0 [Note] InnoDB: Number of pools: 1
2022-07-08T04:11:27.496227Z 0 [Note] InnoDB: Using CPU crc32 instructions
2022-07-08T04:11:27.510618Z 0 [Note] InnoDB: Initializing buffer pool, total size=256M,instances=1,chunk size=128M
2022-07-08T04:11:27.520144Z 0 [Note] InnoDB: Completed initialization of buffer pool
2022-07-08T04:11:27.522095Z 0 [Note] InnoDB: If the mysqld execution user is authorized, 
        page cleaner thread priority can be changed.  See the man page of setpriority().
2022-07-08T04:11:27.532135Z 0 [Note] InnoDB: The first innodb_system data file 'ibdata1' did not exist. 
       A new tablespace will be created!
2022-07-08T04:11:27.532259Z 0 [Note] InnoDB: Setting file '/www/server/data/ibdata1' size to 10 MB. 
        Physically writing the file full; Please wait ...
2022-07-08T04:11:27.760116Z 0 [Note] InnoDB: File '/www/server/data/ibdata1' size is now 10 MB.
2022-07-08T04:11:27.760338Z 0 [Note] InnoDB: Setting log file /www/server/data/ib_logfile101 size to 128MB
2022-07-08T04:11:27.760414Z 0 [Note] InnoDB: Progress in MB:
 100
2022-07-08T04:11:28.940355Z 0 [Note] InnoDB: Setting log file /www/server/data/ib_logfile1 size to 128 MB
2022-07-08T04:11:28.940442Z 0 [Note] InnoDB: Progress in MB:
 100
2022-07-08T04:11:30.517357Z 0 [Note] InnoDB: Renaming log file /www/server/data/ib_logfile101 
      to /www/server/data/ib_logfile0
2022-07-08T04:11:30.517394Z 0 [Warning] InnoDB: New log files created, LSN=45790
2022-07-08T04:11:30.517401Z 0 [Note] InnoDB: Creating shared tablespace for temporary tables
2022-07-08T04:11:30.517425Z 0 [Note] InnoDB: Setting file '/www/server/data/ibtmp1' size to 12 MB. 
       Physically writing the file full; Please wait ...
2022-07-08T04:11:30.609146Z 0 [Note] InnoDB: File '/www/server/data/ibtmp1' size is now 12 MB.
2022-07-08T04:11:30.609236Z 0 [Note] InnoDB: Doublewrite buffer not found: creating new
2022-07-08T04:11:30.631133Z 0 [Note] InnoDB: Doublewrite buffer created
2022-07-08T04:11:31.160847Z 0 [Note] InnoDB: 96 redo rollback segment(s) found.96 redo rollback segment(s) are active.
2022-07-08T04:11:31.160860Z 0 [Note] InnoDB: 32 non-redo rollback segment(s) are active.
2022-07-08T04:11:31.160970Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
2022-07-08T04:11:31.194147Z 0 [Note] InnoDB: Foreign key constraint system tables created
2022-07-08T04:11:31.194175Z 0 [Note] InnoDB: Creating tablespace and datafile system tables.
2022-07-08T04:11:31.195079Z 0 [Note] InnoDB: Tablespace and datafile system tables created.
2022-07-08T04:11:31.195098Z 0 [Note] InnoDB: Creating sys_virtual system tables.
2022-07-08T04:11:31.195974Z 0 [Note] InnoDB: sys_virtual table created
2022-07-08T04:11:31.196099Z 0 [Note] InnoDB: Waiting for purge to start
2022-07-08T04:11:31.246167Z 0 [Note] InnoDB: 5.7.34 started; log sequence number 0
2022-07-08T04:11:31.246379Z 0 [Note] Plugin 'FEDERATED' is disabled.
2022-07-08T04:11:31.248996Z 0 [Warning] InnoDB: Cannot open table mysql/plugin from the internal data dictionary 
        of InnoDB  though the .frm file for the table exists. 
Please refer to http://dev.mysql.com/doc/refman/5.7/en/innodb-troubleshooting.html for how to resolve the issue.
mysqld: Table 'mysql.plugin' doesn't exist

通过上述日志可以确认,数据库应该被重新初始化了,导致以前库的ibd和frm文件无法被正常访问.对于此类情况,可以参考以前类似恢复案例:frm和ibd文件数据库恢复

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