产生的问题
在安装MySQL 5.6时，安装完成后，后台日志报如下警告信息。
2021-05-03 13:47:34 22946 [Warning] InnoDB: Cannot open table mysql/slave_master_info from the internal data dictionary of InnoDB though the .frm file for the table exists. See http://dev.mysql.com/doc/refman/5.6/en/innodb-troubleshooting.html for how you can resolve the problem. 2021-05-03 13:47:34 22946 [Warning] Info table is not ready to be used. Table 'mysql.slave_master_info' cannot be opened. 2021-05-03 13:47:34 22946 [Warning] InnoDB: Cannot open table mysql/slave_worker_info from the internal data dictionary of InnoDB though the .frm file for the table exists. See http://dev.mysql.com/doc/refman/5.6/en/innodb-troubleshooting.html for how you can resolve the problem. 2021-05-03 13:47:34 22946 [Warning] InnoDB: Cannot open table mysql/slave_relay_log_info from the internal data dictionary of InnoDB though the .frm file for the table exists. See http://dev.mysql.com/doc/refman/5.6/en/innodb-troubleshooting.html for how you can resolve the problem. 2021-05-03 13:47:34 22946 [Warning] Info table is not ready to be used. Table 'mysql.slave_relay_log_info' cannot be opened. ....... 2021-05-03 13:49:33 22946 [Warning] InnoDB: Cannot open table mysql/innodb_index_stats from the internal data dictionary of InnoDB though the .frm file for the table exists. See http://dev.mysql.com/doc/refman/5.6/en/innodb-troubleshooting.html for how you can resolve the problem. 2021-05-03 13:49:49 7f3ae82a5700 InnoDB: Error: table `mysql`.`innodb_index_stats` does not exist in the InnoDB internal
问题原因
网上查找到的资料表示：数据库打开这几张表的默认引擎为MyISAM，但是这几张表在建表时的引擎为InnoDB，但是能确定的，这几张表确实是在mysql5.6中新入的。
innodb_index_stats, innodb_tables_stats, slave_master_info, slave_relay_log_info, slave_worker_info
解决方法
(1) 登录数据库，进入MySQL库，执行如下SQL删除5张表
记住，一定要用drop table if exists
drop table if exists innodb_index_stats; drop table if exists innodb_table_stats; drop table if exists slave_master_info; drop table if exists slave_relay_log_info; drop table if exists slave_worker_info;
如下是执行的结果，忽略你看到的Warning信息
binghe@localhost : mysql 02:12:26> drop table if exists innodb_index_stats; Query OK, 0 rows affected, 1 warning (0.00 sec) Warning (Code 155): Table 'mysql.innodb_index_stats' doesn't exist binghe@localhost : mysql 02:12:26> drop table if exists innodb_table_stats; Query OK, 0 rows affected, 1 warning (0.00 sec) Warning (Code 155): Table 'mysql.innodb_table_stats' doesn't exist binghe@localhost : mysql 02:12:26> drop table if exists slave_master_info; Query OK, 0 rows affected, 1 warning (0.00 sec) Warning (Code 155): Table 'mysql.slave_master_info' doesn't exist binghe@localhost : mysql 02:12:27> drop table if exists slave_relay_log_info; Query OK, 0 rows affected, 1 warning (0.00 sec) Warning (Code 155): Table 'mysql.slave_relay_log_info' doesn't exist binghe@localhost : mysql 02:12:27> drop table if exists slave_worker_info; Query OK, 0 rows affected, 1 warning (0.00 sec) Warning (Code 155): Table 'mysql.slave_worker_info' doesn't exist
执行完后，可以用show tables查看一下，看表的数据是否已经比删除之前减少了，如果减少了，说明你成功了！
(2)面这一部操作完成后，停止数据库，并进入到数据库数据文件所在目录，删除表面5个表所对应的idb文件，如下所示：
[binghe@localhost] /data/mysqldata3/mydata/mysql]ls *.ibd innodb_index_stats.ibd innodb_table_stats.ibd slave_master_info.ibd slave_relay_log_info.ibd slave_worker_info.ibd [binghe@localhost] /data/mysqldata3/mydata/mysql]rm -f *.ibd
(3) 重新启动数据库，进入到mysql库，重建上面被删除的表结构：数据库的建设表脚本在mysql软件的安装目录的share目录下，我的mysql软件的安装路径为/usr/test/mysql
binghe@localhost : (none) 02:23:03> use mysql Database changed
如下是执行建表脚本前表的数量：
binghe@localhost : mysql 02:23:48> source /usr/test/mysql/share/mysql_system_tables.sql binghe@localhost : mysql 02:23:50> show tables; +---------------------------+ | Tables_in_mysql | +---------------------------+ | columns_priv | | db | | event | | func | | general_log | | help_category | | help_keyword | | help_relation | | help_topic | | ndb_binlog_index | | plugin | | proc | | procs_priv | | proxies_priv | | servers | | slow_log | | tables_priv | | time_zone | | time_zone_leap_second | | time_zone_name | | time_zone_transition | | time_zone_transition_type | | user | +---------------------------+ 23 rows in set (0.00 sec)
如下为执行建表脚本后，表的数量
binghe@localhost : mysql 02:23:46> show tables; +---------------------------+ | Tables_in_mysql | +---------------------------+ | columns_priv | | db | | event | | func | | general_log | | help_category | | help_keyword | | help_relation | | help_topic | | innodb_index_stats | | innodb_table_stats | | ndb_binlog_index | | plugin | | proc | | procs_priv | | proxies_priv | | servers | | slave_master_info | | slave_relay_log_info | | slave_worker_info | | slow_log | | tables_priv | | time_zone | | time_zone_leap_second | | time_zone_name | | time_zone_transition | | time_zone_transition_type | | user | +---------------------------+ 28 rows in set (0.00 sec)
(4) 用show create table命令查看表时，也很正常，后台日志中也不再报与上面提到的5张表相关的错误，到此，问题全部解决！
后记：在后面的环境中，配置双主架构时，又遇到了如下问题：
error: ERROR 1794 (HY000): Slave is not configured or failed to initialize properly. You must at least set --server-id to enable either a master or a slave. Additional error messages can be found in the MySQL error log.
最后通过如下的操作解决的问题。
(1)登录数据库后，删除5张表，并重新导入脚本
use mysql; drop table slave_master_info; drop table slave_relay_log_info; drop table slave_worker_info; drop table innodb_index_stats; drop table innodb_table_stats; source /usr/local/mysql/share/mysql_system_tables.sql;
(2)重新启动数据库
注：这一步是必须的，否则无法正常配置双主架构。
