为什么使用MyISAM引擎而不是InnoDB创build默认的'mysql'数据库?

我正在使用MySQL version 5.6 ,它具有InnoDB的默认MySQL引擎,即如果在创build表时未指定引擎,则使用InnoDB创build。

但今天,我注意到默认的mysql数据库是使用'MyISAM'而不是InnoDB创build的。

任何线索,为什么如此?

 Database changed mysql> 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) 

这是我的cnf文件:

 # For advice on how to change settings please see # http://dev.mysql.com/doc/refman/5.6/en/server-configuration-defaults.html [mysqld] init-connect='SET NAMES utf8' max_connections = 500 # # Remove leading # and set to the amount of RAM for the most important data # cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%. # innodb_buffer_pool_size = 128M # # Remove leading # to turn on a very important data integrity option: logging # changes to the binary log between backups. # log_bin # # Remove leading # to set options mainly useful for reporting servers. # The server defaults are faster for transactions and fast SELECTs. # Adjust sizes as needed, experiment to find the optimal values. # join_buffer_size = 128M # sort_buffer_size = 2M # read_rnd_buffer_size = 2M datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock # Disabling symbolic-links is recommended to prevent assorted security risks symbolic-links=0 # Recommended in standard MySQL setup #sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES [mysqld_safe] log-error=/var/log/mysqld.log pid-file=/var/run/mysqld/mysqld.pid 

以下是其中一个表的mysqldump:

 CREATE TABLE `columns_priv` ( `Host` char(60) COLLATE utf8_bin NOT NULL DEFAULT '', `Db` char(64) COLLATE utf8_bin NOT NULL DEFAULT '', `User` char(16) COLLATE utf8_bin NOT NULL DEFAULT '', `Table_name` char(64) COLLATE utf8_bin NOT NULL DEFAULT '', `Column_name` char(64) COLLATE utf8_bin NOT NULL DEFAULT '', `Timestamp` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP, `Column_priv` set('Select','Insert','Update','References') CHARACTER SET utf8 NOT NULL DEFAULT '', PRIMARY KEY (`Host`,`Db`,`User`,`Table_name`,`Column_name`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_bin COMMENT='Column privileges'; 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 | | MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO | | BLACKHOLE | YES | /dev/null storage engine (anything you write to it disappears) | NO | NO | NO | | MyISAM | YES | MyISAM storage engine | NO | NO | NO | | FEDERATED | NO | Federated MySQL storage engine | NULL | NULL | NULL | | ARCHIVE | YES | Archive storage engine | NO | NO | NO | | InnoDB | DEFAULT | Supports transactions, row-level locking, and foreign keys | YES | YES | YES | | PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO | +--------------------+---------+----------------------------------------------------------------+--------------+------+------------+ 

14.5.4将表格从MyISAM转换到InnoDB

重要

不要将MySQL数据库(如用户或主机)中的MySQL系统表转换为InnoDB类型。 这是一个不受支持的操作。 系统表必须始终为MyISAM类型。