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

AlterResourceGroupStmt ::=
   "ALTER" "RESOURCE" "GROUP" IfExists ResourceGroupName ResourceGroupOptionList
IfExists ::=
    ('IF' 'EXISTS')?
ResourceGroupName ::=
   Identifier
ResourceGroupOptionList ::=
    DirectResourceGroupOption
|   ResourceGroupOptionList DirectResourceGroupOption
|   ResourceGroupOptionList ',' DirectResourceGroupOption
DirectResourceGroupOption ::=
    "RU_PER_SEC" EqOpt stringLit
|   "PRIORITY" EqOpt ResourceGroupPriorityOption
|   "BURSTABLE"
ResourceGroupPriorityOption ::=
    LOW 
|   MEDIUM
|   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。

DROP RESOURCE GROUP IF EXISTS rg1;

Query OK, 0 rows affected (0.22 sec)

CREATE RESOURCE GROUP IF NOT EXISTS rg1
  RU_PER_SEC = 100
  BURSTABLE;

Query OK, 0 rows affected (0.08 sec)

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

+------+------------+----------+-----------+
| NAME | RU_PER_SEC | PRIORITY | BURSTABLE |
+------+------------+----------+-----------+
| rg1  |       100  | MEDIUM   | YES       |
+------+------------+----------+-----------+
1 rows in set (1.30 sec)

ALTER RESOURCE GROUP rg1
  RU_PER_SEC = 200
  PRIORITY = LOW;

Query OK, 0 rows affected (0.08 sec)

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

+------+------------+----------+-----------+
| NAME | RU_PER_SEC | PRIORITY | BURSTABLE |
+------+------------+----------+-----------+
| rg1  |       200  | LOW      | NO        |
+------+------------+----------+-----------+
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