ENGINES
ENGINES 表提供了关于存储引擎的信息。从和 MySQL 兼容性上考虑，TiDB 会一直将 InnoDB 描述为唯一支持的引擎。此外，ENGINES 表中其它列值也都是定值。
USE information_schema;
DESC engines;
+--------------+-------------+------+------+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------------+-------------+------+------+---------+-------+
| ENGINE | varchar(64) | YES | | NULL | |
| SUPPORT | varchar(8) | YES | | NULL | |
| COMMENT | varchar(80) | YES | | NULL | |
| TRANSACTIONS | varchar(3) | YES | | NULL | |
| XA | varchar(3) | YES | | NULL | |
| SAVEPOINTS | varchar(3) | YES | | NULL | |
+--------------+-------------+------+------+---------+-------+
6 rows in set (0.00 sec)
SELECT * FROM engines;
+--------+---------+------------------------------------------------------------+--------------+------+------------+
| ENGINE | SUPPORT | COMMENT | TRANSACTIONS | XA | SAVEPOINTS |
+--------+---------+------------------------------------------------------------+--------------+------+------------+
| InnoDB | DEFAULT | Supports transactions, row-level locking, and foreign keys | YES | YES | YES |
+--------+---------+------------------------------------------------------------+--------------+------+------------+
1 row in set (0.01 sec)
ENGINES 表中列的含义如下：
ENGINE：存储引擎的名称。SUPPORT：服务器对存储引擎的支持级别，在 TiDB 中此值一直是DEFAULT。COMMENT：存储引擎的简要描述。TRANSACTIONS：存储引擎是否支持事务。XA：存储引擎是否支持 XA 事务。SAVEPOINTS：存储引擎是否支持savepoints。