分类目录归档：MySQL

修改MySQL的ib_logfile大小和组数

发表于 2022 年 7 月 16 日 由 惜分飞

在某些情况下，需要修改MySQL的ib_logfile大小和组数(类似oracle redo),以下演示在MySQL 8.0修改ib_logfile大小和组数操作
查看当前ib_logfile情况

mysql> select version();
+-----------+
| version() |
+-----------+
| 8.0.21    |
+-----------+
1 row in set (0.00 sec)

mysql> show variables like '%innodb_log_file%';
+---------------------------+-----------+
| Variable_name             | Value     |
+---------------------------+-----------+
| innodb_log_file_size      | 134217728 |
| innodb_log_files_in_group | 2         |
+---------------------------+-----------+
2 rows in set, 1 warning (0.00 sec)

mysql> show variables like '%innodb_log_group_home_dir%';
+---------------------------+-------+
| Variable_name             | Value |
+---------------------------+-------+
| innodb_log_group_home_dir | .\    |
+---------------------------+-------+
1 row in set, 1 warning (0.00 sec)

mysql> show variables like '%datadir%';
+---------------+---------------+
| Variable_name | Value         |
+---------------+---------------+
| datadir       | E:\MySQL\8.0\ |
+---------------+---------------+
1 row in set, 1 warning (0.00 sec)

C:\Users\XFF>dir E:\MySQL\8.0\ib_log*
 驱动器 E 中的卷是 SSD
 卷的序列号是 98A5-7F8E

 E:\MySQL\8.0 的目录

2022-07-16  14:14       134,217,728 ib_logfile0
2022-07-03  17:30       134,217,728 ib_logfile1
               2 个文件    268,435,456 字节
               0 个目录 807,501,471,744 可用字节

当前ib_logfile成员为2个,每个128M,后续计划修改为成为3个,每个256M

修改my.ini参数

innodb_log_files_in_group=3
innodb_log_file_size=256M

重启mysql服务

C:\Users\XFF>dir E:\MySQL\8.0\ib_log*
 驱动器 E 中的卷是 SSD
 卷的序列号是 98A5-7F8E

 E:\MySQL\8.0 的目录

2022-07-16  14:19       268,435,456 ib_logfile0
2022-07-16  14:19       268,435,456 ib_logfile1
2022-07-16  14:19       268,435,456 ib_logfile2
               3 个文件    805,306,368 字节
               0 个目录 806,964,072,448 可用字节


mysql> show variables like '%innodb_log_file%';
+---------------------------+-----------+
| Variable_name             | Value     |
+---------------------------+-----------+
| innodb_log_file_size      | 268435456 |
| innodb_log_files_in_group | 3         |
+---------------------------+-----------+
2 rows in set, 1 warning (0.00 sec)

在8.0版本中直接修改成功,如果是以前MySQL版本,修改过程可能遭遇InnoDB: Error: log file ./ib_logfile0 is of different size 0 268435456 bytes错误,类似这样的需要删除ib_logfile文件,启动MySQL服务重新生成ib_logfile文件(在8.0版本中直接自动删除并重建)

发表在 MySQL | 标签为 | 评论关闭

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.

发表在 MySQL恢复 | 标签为 , , | 评论关闭

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

发表在 MySQL恢复 | 标签为 , , , , | 评论关闭