为什么默认'；mysql'；使用MyISAM引擎而不是InnoDB创建的数据库？

我使用的是MySQL 5.6版，它的默认MySQL引擎是InnoDB，也就是说，如果在创建表时没有指定引擎，那么它是使用InnoDB创建的

但是今天，我注意到默认的

mysql

数据库是使用“MyISAM”而不是InnoDB创建的

任何线索，为什么会这样

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         |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+

重要

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

---

没有检查表是否为系统表。接得好+1谢谢。但是有任何线索，为什么MySQL 5.7和5.6中的默认引擎是InnoDB时，系统表保持MyISAM格式？@kingsmasher1:From 5.5 InnoDB是默认引擎，文档在这一点上不是很明确：

MySQL`和information_schema`数据库，实现了一些MySQL内部结构，仍然使用MyISAM。特别是，您不能切换授权表以使用InnoDB。

。请看。这对于最新的MySQL版本仍然有效吗？@W.M:我不能保证它同样适用于MariaDB，MariaDB的文档在这方面不是很明确，请看。您可以读取以下错误报告：。使用MariaDB 10.3.7，我无法重现错误报告中描述的错误。