MySQL: Unknown table engine 'InnoDB' 问题解决
问题出现环境：
CentOS 6.10, MySQL 5.1.73
问题现象：
对表做select操作的时候，出现如下的错误：
1286 - Unknown table engine 'InnoDB’
问题出现经过：
在搭建一个既有系统的开发环境的时候，做了一下mysql的数据转存操作。
操作比较原始一些，就是把数据库文件ibdatan文件，ib_logfilen文件替换原来的文件。从客户端登上去看的时候，数据库里面的表都看不见了。尝试了一下select count(*) from tableA的操作，出现了“ Unknown table engine ‘InnoDB’”这样的错误。
错误原因
主要本次安装的MySQL为5.1，没有安装InnoDB。MySQL 5.5开始，将默认数据库存储引擎从MyISAM改为InnoDB，就不会有这些问题了。这之前的办法要另行安装。
登入mysql客户端，通过show engines命令，可以看到innodb的安装情况。
mysql> show engines;
+------------+---------+-----------------------------------------------------------+--------------+------+------------+
| Engine | Support | Comment | Transactions | XA | Savepoints |
+------------+---------+-----------------------------------------------------------+--------------+------+------------+
| MRG_MYISAM | YES | Collection of identical MyISAM tables | NO | NO | NO |
| CSV | YES | CSV storage engine | NO | NO | NO |
| MyISAM | DEFAULT | Default engine as of MySQL 3.23 with great performance | NO | NO | NO |
| MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO |
+------------+---------+-----------------------------------------------------------+--------------+------+------------+
4 rows in set (0.00 sec)
可以看到没有安装innodb。
当然，还有可能安装了之后没有启用。 下面的办法可以确认到安装并已经启用(YES),安装了没有启用(DISABLE)，没有安装(NO) 。下表中可以看到没有安装。
mysql> SHOW VARIABLES LIKE 'have_%';
+-------------------------+----------+
| Variable_name | Value |
+-------------------------+----------+
| have_community_features | YES |
| have_compress | YES |
| have_crypt | YES |
| have_csv | YES |
| have_dynamic_loading | YES |
| have_geometry | YES |
| have_innodb | NO |
| have_ndbcluster | NO |
| have_openssl | DISABLED |
| have_partitioning | YES |
| have_query_cache | YES |
| have_rtree_keys | YES |
| have_ssl | DISABLED |
| have_symlink | DISABLED |
+-------------------------+----------+
14 rows in set (0.00 sec)
mysql> show plugins;
+------------+--------+----------------+---------+---------+
| Name | Status | Type | Library | License |
+------------+--------+----------------+---------+---------+
| binlog | ACTIVE | STORAGE ENGINE | NULL | GPL |
| partition | ACTIVE | STORAGE ENGINE | NULL | GPL |
| CSV | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MEMORY | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MyISAM | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MRG_MYISAM | ACTIVE | STORAGE ENGINE | NULL | GPL |
+------------+--------+----------------+---------+---------+
6 rows in set (0.00 sec)
解决办法
主要是安装并启用InnoDB引擎。MySQL在5.1.38之后，InnoDB引擎是包含在一起的。主要还相对省事一些。
- 确定MySQL的plugin的安装目录
mysql> SHOW variables like "plugin_dir";
+---------------+-------------------------+
| Variable_name | Value |
+---------------+-------------------------+
| plugin_dir | /usr/lib64/mysql/plugin |
+---------------+-------------------------+
1 row in set (0.00 sec)
- 查找是否已经存在innodb的so
在plugin目录中确认是否有InnoDB的so文件。
如果不存在 则从mysql的安装结构中将innodb so拷贝到plugins_dir目录中。
lrwxrwxrwx 1 root root 25 Apr 5 22:04 ha_innodb_plugin.so -> ha_innodb_plugin.so.0.0.0
lrwxrwxrwx 1 root root 25 Apr 5 22:04 ha_innodb_plugin.so.0 -> ha_innodb_plugin.so.0.0.0
-rwxr-xr-x 1 root root 1259136 Jan 27 2017 ha_innodb_plugin.so.0.0.0
- 安装InnoDB引擎
编辑/etc/my.cnf文件，在[mysqld]下面添加如下内容：
ignore-builtin-innodb
plugin-load=innodb=ha_innodb_plugin.so
plugin_dir=/usr/lib64/mysql/plugin
注意根据1,2的调查结果更改上面相应的内容。
- 重启动mysql
service mysqld restart
#或者
/etc/init.d/mysqld restart
-
检查是否正确启用InnoDB.
使用上文中提到的 show engines / show plugins / SHOW VARIABLES LIKE 'have_%'等方法进行确认。
如果还是不能正确安装，可以查看mysql错误日志。 -
确认错误日志
如果是service方式启动的mysql服务器，通过下面的命令可以看到错误日志位置。
# ps -ef|grep mysqld
root 4454 1 0 23:09 pts/0 00:00:00 /bin/sh /usr/bin/mysqld_safe --datadir=/var/lib/mysql --socket=/var/lib/mysql/mysql.sock --pid-file=/var/run/mysqld/mysqld.pid --basedir=/usr --user=mysql
mysql 4565 4454 0 23:09 pts/0 00:00:00 /usr/libexec/mysqld --basedir=/usr --datadir=/var/lib/mysql --user=mysql --log-error=/var/log/mysqld.log --pid-file=/var/run/mysqld/mysqld.pid --socket=/var/lib/mysql/mysql.sock
root 4590 3339 0 23:13 pts/0 00:00:00 grep mysqld
本次报告的是如下错误：日志文件尺寸不一致错误。因为我是用的覆盖的方式刷新数据库文件的。
决定删除数据库日志文件试试。
再次确认安装情况，OK！
mysql> show engines;
+------------+---------+------------------------------------------------------------+--------------+------+------------+
| Engine | Support | Comment | Transactions | XA | Savepoints |
+------------+---------+------------------------------------------------------------+--------------+------+------------+
| InnoDB | YES | Supports transactions, row-level locking, and foreign keys | YES | YES | YES |
| CSV | YES | CSV storage engine | NO | NO | NO |
| MRG_MYISAM | YES | Collection of identical MyISAM tables | NO | NO | NO |
| MyISAM | DEFAULT | Default engine as of MySQL 3.23 with great performance | NO | NO | NO |
| MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO |
+------------+---------+------------------------------------------------------------+--------------+------+------------+
5 rows in set (0.00 sec)
mysql> show plugins
-> ;
+------------+--------+----------------+---------------------+---------+
| Name | Status | Type | Library | License |
+------------+--------+----------------+---------------------+---------+
| binlog | ACTIVE | STORAGE ENGINE | NULL | GPL |
| partition | ACTIVE | STORAGE ENGINE | NULL | GPL |
| CSV | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MEMORY | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MyISAM | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MRG_MYISAM | ACTIVE | STORAGE ENGINE | NULL | GPL |
| InnoDB | ACTIVE | STORAGE ENGINE | ha_innodb_plugin.so | GPL |
+------------+--------+----------------+---------------------+---------+
7 rows in set (0.00 sec)
mysql> SHOW VARIABLES LIKE 'have_%';
+-------------------------+----------+
| Variable_name | Value |
+-------------------------+----------+
| have_community_features | YES |
| have_compress | YES |
| have_crypt | YES |
| have_csv | YES |
| have_dynamic_loading | YES |
| have_geometry | YES |
| have_innodb | YES |
| have_ndbcluster | NO |
| have_openssl | DISABLED |
| have_partitioning | YES |
| have_query_cache | YES |
| have_rtree_keys | YES |
| have_ssl | DISABLED |
| have_symlink | DISABLED |
+-------------------------+----------+
14 rows in set (0.00 sec)
参考：MySQL5.1: 安装启用InnoDB引擎