为什么MGR需要用主键

为什么MGR需要使用主键？针对这个问题，今天小编总结这篇有关MGR表的文章，希望能帮助更多想解决这个问题的朋友找到更加简单易行的办法。

验证MGR架构表需要使用主键，不然插入数据会报错。

mysql> show tables;
+--------------+
| Tables_in_dd |
+--------------+
| a            |
+--------------+
1 row in set (0.00 sec)

mysql> desc a;
+-------+---------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+-------+
| id    | int(11) | YES  |     | NULL    |       |
+-------+---------+------+-----+---------+-------+
1 row in set (0.00 sec)

mysql> insert into a values(1);
ERROR 3098 (HY000): The table does not comply with the requirements by an external plugin.

mysql> alter table a add primary key (id);
Query OK, 0 rows affected (0.02 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc a;
+-------+---------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+-------+
| id    | int(11) | NO   | PRI | NULL    |       |
+-------+---------+------+-----+---------+-------+
1 row in set (0.01 sec)

mysql> insert into a values(1);
Query OK, 1 row affected (0.00 sec)
mysql> insert into a values(1);
Query OK, 1 row affected (0.00 sec)

mysql> select * from a;
+----+
| id |
+----+
|  1 |
+----+
1 row in set (0.00 sec)

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