问题：打开mysql错误日志时发现大量的如下错误
Error: Table “mysql”.”innodb_table_stats” not found.
InnoDB: Recalculation of persistent statistics requested for table “xxx”.”xxx” but the required persistent statistics storage is not present or is corrupted. Using transient stats instead.
该错误是MYSQL 5.6版本下的一个BUG。
虽然不会影响数据库的正常使用，但是它会不断生成错误日志，如果网站访问量比较大，可能短时间内就占满硬盘，导致各项服务出错。
产生该问题的原因是，在mysql 5.6版本下，新增了以下五个表。
innodb_index_stats,
innodb_tables_stats,
slave_master_info,
slave_relay_log_info,
slave_worker_info
这五个表的存储类型是innodb，而默认情况下数据库打开这五张表的方式是MyISAM。
【解决方案】：
先看看能否drop table，如果说表不存在，则继续下一步。
DROP TABLE mysql.innodb_index_stats; DROP TABLE mysql.innodb_table_stats; DROP TABLE mysql.slave_master_info; DROP TABLE mysql.slave_relay_log_info; DROP TABLE mysql.slave_worker_info;
删除datadir下mysql数据库中的这五张表的frm文件（如有ibd也一并删除）
rm -rf $datadir/mysql/innodb_index_stats.* rm -rf $datadir/mysql/innodb_table_stats.* rm -rf $datadir/mysql/slave_master_info.* rm -rf $datadir/mysql/slave_relay_log_info.* rm -rf $datadir/mysql/slave_worker_info.*
最后执行下列sql语句重新创建这5张表
USE mysql; CREATE TABLE `innodb_index_stats` ( `database_name` varchar(64) COLLATE utf8_bin NOT NULL, `table_name` varchar(64) COLLATE utf8_bin NOT NULL, `index_name` varchar(64) COLLATE utf8_bin NOT NULL, `last_update` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP, `stat_name` varchar(64) COLLATE utf8_bin NOT NULL, `stat_value` bigint(20) unsigned NOT NULL, `sample_size` bigint(20) unsigned DEFAULT NULL, `stat_description` varchar(1024) COLLATE utf8_bin NOT NULL, PRIMARY KEY (`database_name`,`table_name`,`index_name`,`stat_name`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin STATS_PERSISTENT=0; CREATE TABLE `innodb_table_stats` ( `database_name` varchar(64) COLLATE utf8_bin NOT NULL, `table_name` varchar(64) COLLATE utf8_bin NOT NULL, `last_update` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP, `n_rows` bigint(20) unsigned NOT NULL, `clustered_index_size` bigint(20) unsigned NOT NULL, `sum_of_other_index_sizes` bigint(20) unsigned NOT NULL, PRIMARY KEY (`database_name`,`table_name`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin STATS_PERSISTENT=0; CREATE TABLE `slave_master_info` ( `Number_of_lines` int(10) unsigned NOT NULL COMMENT 'Number of lines in the file.', `Master_log_name` text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL COMMENT 'The name of the master binary log currently being read from the master.', `Master_log_pos` bigint(20) unsigned NOT NULL COMMENT 'The master log position of the last read event.', `Host` char(64) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL DEFAULT '' COMMENT 'The host name of the master.', `User_name` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The user name used to connect to the master.', `User_password` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The password used to connect to the master.', `Port` int(10) unsigned NOT NULL COMMENT 'The network port used to connect to the master.', `Connect_retry` int(10) unsigned NOT NULL COMMENT 'The period (in seconds) that the slave will wait before trying to reconnect to the master.', `Enabled_ssl` tinyint(1) NOT NULL COMMENT 'Indicates whether the server supports SSL connections.', `Ssl_ca` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The file used for the Certificate Authority (CA) certificate.', `Ssl_capath` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The path to the Certificate Authority (CA) certificates.', `Ssl_cert` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The name of the SSL certificate file.', `Ssl_cipher` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The name of the cipher in use for the SSL connection.', `Ssl_key` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The name of the SSL key file.', `Ssl_verify_server_cert` tinyint(1) NOT NULL COMMENT 'Whether to verify the server certificate.', `Heartbeat` float NOT NULL, `Bind` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'Displays which interface is employed when connecting to the MySQL server', `Ignored_server_ids` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The number of server IDs to be ignored, followed by the actual server IDs', `Uuid` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The master server uuid.', `Retry_count` bigint(20) unsigned NOT NULL COMMENT 'Number of reconnect attempts, to the master, before giving up.', `Ssl_crl` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The file used for the Certificate Revocation List (CRL)', `Ssl_crlpath` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The path used for Certificate Revocation List (CRL) files', `Enabled_auto_position` tinyint(1) NOT NULL COMMENT 'Indicates whether GTIDs will be used to retrieve events from the master.', PRIMARY KEY (`Host`,`Port`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 STATS_PERSISTENT=0 COMMENT='Master Information'; CREATE TABLE `slave_relay_log_info` ( `Number_of_lines` int(10) unsigned NOT NULL COMMENT 'Number of lines in the file or rows in the table. Used to version table definitions.', `Relay_log_name` text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL COMMENT 'The name of the current relay log file.', `Relay_log_pos` bigint(20) unsigned NOT NULL COMMENT 'The relay log position of the last executed event.', `Master_log_name` text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL COMMENT 'The name of the master binary log file from which the events in the relay log file were read.', `Master_log_pos` bigint(20) unsigned NOT NULL COMMENT 'The master log position of the last executed event.', `Sql_delay` int(11) NOT NULL COMMENT 'The number of seconds that the slave must lag behind the master.', `Number_of_workers` int(10) unsigned NOT NULL, `Id` int(10) unsigned NOT NULL COMMENT 'Internal Id that uniquely identifies this record.', PRIMARY KEY (`Id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 STATS_PERSISTENT=0 COMMENT='Relay Log Information'; CREATE TABLE `slave_worker_info` ( `Id` int(10) unsigned NOT NULL, `Relay_log_name` text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL, `Relay_log_pos` bigint(20) unsigned NOT NULL, `Master_log_name` text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL, `Master_log_pos` bigint(20) unsigned NOT NULL, `Checkpoint_relay_log_name` text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL, `Checkpoint_relay_log_pos` bigint(20) unsigned NOT NULL, `Checkpoint_master_log_name` text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL, `Checkpoint_master_log_pos` bigint(20) unsigned NOT NULL, `Checkpoint_seqno` int(10) unsigned NOT NULL, `Checkpoint_group_size` int(10) unsigned NOT NULL, `Checkpoint_group_bitmap` blob NOT NULL, PRIMARY KEY (`Id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 STATS_PERSISTENT=0 COMMENT='Worker Information';
