主要是两个：MyISAM 和 InnoDB。
MyISAM的表在磁盘上存储成 3 个文件，其文件名都和表名相同，扩展名分别是：.frm（存储表定义） .MYD（MYData，存储数据） .MYI （MYIndex，存储索引）
InnoDB的表在磁盘上有两个文件，其文件名都和表名相同，扩展名分别是：.frm（存储表的定义） .ibd（存储数据和索引）
MEMORY只有一个：.frm（表结构定义）。数据存在内存，默认使用HASH索引
可以使用这句话查看

root@wu-virtual-machine:/var/lib/mysql/mysql# ls

5.7 是个分界线，在它之前是MyISAM，从它开始是InnoDB。

mysql> show engines;
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| Engine             | Support | Comment                                                        | Transactions | XA   | Savepoints |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| InnoDB             | DEFAULT | Supports transactions, row-level locking, and foreign keys     | YES          | YES  | YES        |
| MRG_MYISAM         | YES     | Collection of identical MyISAM tables                          | 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         |
| CSV                | YES     | CSV storage engine                                             | NO           | NO   | NO         |
| ARCHIVE            | YES     | Archive storage engine                                         | NO           | NO   | NO         |
| PERFORMANCE_SCHEMA | YES     | Performance Schema                                             | NO           | NO   | NO         |
| FEDERATED          | NO      | Federated MySQL storage engine                                 | NULL         | NULL | NULL       |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
9 rows in set (0.00 sec)

可以这样查看表的索引引擎是啥

mysql> show create table student\G
*************************** 1. row ***************************
       Table: student
Create Table: CREATE TABLE `student` (
  `uid` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(50) NOT NULL,
  `age` tinyint(3) unsigned NOT NULL,
  `sex` enum('M','W') NOT NULL,
  PRIMARY KEY (`uid`)
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

对比图