ALTER RESOURCE GROUP
The ALTER RESOURCE GROUP statement is used to modify a resource group in a database.
Synopsis
- 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 supports the following DirectResourceGroupOption, where Request Unit (RU) is a unified abstraction unit in TiDB for CPU, IO, and other system resources.
| Option | Description | Example |
|---|---|---|
RU_PER_SEC | Rate of RU backfilling per second | RU_PER_SEC = 500 indicates that this resource group is backfilled with 500 RUs per second |
PRIORITY | The absolute priority of tasks to be processed on TiKV | PRIORITY = HIGH indicates that the priority is high. If not specified, the default value is MEDIUM. |
BURSTABLE | If the BURSTABLE attribute is set, TiDB allows the corresponding resource group to use the available system resources when the quota is exceeded. |
Examples
Create a resource group named rg1 and modify its properties.
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 compatibility
MySQL also supports ALTER RESOURCE GROUP. However, the acceptable parameters are different from that of TiDB so that they are not compatible.