Skip to content

Latest commit

 

History

History
121 lines (91 loc) · 3.57 KB

sql-statement-alter-resource-group.md

File metadata and controls

121 lines (91 loc) · 3.57 KB
Raw
title summary
ALTER RESOURCE GROUP
Learn the usage of ALTER RESOURCE GROUP in TiDB.

ALTER RESOURCE GROUP

Note:

This feature is not available on TiDB Serverless clusters.

The ALTER RESOURCE GROUP statement is used to modify a resource group in a database.

Synopsis

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.

Note:

The ALTER RESOURCE GROUP statement can only be executed when the global variable tidb_enable_resource_control is set to ON.

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.

See also