ALTER RESOURCE GROUP

ALTER RESOURCE GROUP 语句用于在当前所选数据库中修改资源组。

语法图

AlterResourceGroupStmt

IfExists

ResourceGroupName

ResourceGroupOptionList

DirectResourceGroupOption

ResourceGroupPriorityOption

1. AlterResourceGroupStmt ::=
2. "ALTER" "RESOURCE" "GROUP" IfExists ResourceGroupName ResourceGroupOptionList

4. IfExists ::=
5. ('IF' 'EXISTS')?

7. ResourceGroupName ::=
8. Identifier

10. ResourceGroupOptionList ::=
11. DirectResourceGroupOption
12. |   ResourceGroupOptionList DirectResourceGroupOption
13. |   ResourceGroupOptionList ',' DirectResourceGroupOption

15. DirectResourceGroupOption ::=
16. "RU_PER_SEC" EqOpt stringLit
17. |   "PRIORITY" EqOpt ResourceGroupPriorityOption
18. |   "BURSTABLE"

20. ResourceGroupPriorityOption ::=
21. LOW
22. |   MEDIUM
23. |   HIGH

TiDB 支持以下 DirectResourceGroupOption, 其中 Request Unit (RU) 是 TiDB 对 CPU、IO 等系统资源统一抽象的单位。

注意

ALTER RESOURCE GROUP 语句只能在全局变量 tidb_enable_resource_control 参数设置为 ON 时才能执行。

示例

创建一个名为 rg1 的资源组，并修改它的属性。

1. DROP RESOURCE GROUP IF EXISTS rg1;

1. Query OK, 0 rows affected (0.22 sec)

1. CREATE RESOURCE GROUP IF NOT EXISTS rg1
2. RU_PER_SEC = 100
3. BURSTABLE;

1. Query OK, 0 rows affected (0.08 sec)

1. SELECT * FROM information_schema.resource_groups WHERE NAME ='rg1';

1. +------+------------+----------+-----------+
2. | NAME | RU_PER_SEC | PRIORITY | BURSTABLE |
3. +------+------------+----------+-----------+
4. | rg1  |       100  | MEDIUM   | YES       |
5. +------+------------+----------+-----------+
6. 1 rows in set (1.30 sec)

1. ALTER RESOURCE GROUP rg1
2. RU_PER_SEC = 200
3. PRIORITY = LOW;

1. Query OK, 0 rows affected (0.08 sec)

1. SELECT * FROM information_schema.resource_groups WHERE NAME ='rg1';

1. +------+------------+----------+-----------+
2. | NAME | RU_PER_SEC | PRIORITY | BURSTABLE |
3. +------+------------+----------+-----------+
4. | rg1  |       200  | LOW      | NO        |
5. +------+------------+----------+-----------+
6. 1 rows in set (1.30 sec)

MySQL 兼容性

MySQL 也支持 ALTER RESOURCE GROUP，但是接受的参数和 TiDB 不同，两者并不兼容。

另请参阅

• DROP RESOURCE GROUP
• CREATE RESOURCE GROUP
• RU