information-schema-resource-groups.md

title	summary
RESOURCE_GROUPS	Learn the `RESOURCE_GROUPS` information_schema table.

RESOURCE_GROUPS

The RESOURCE_GROUPS table shows the information about all resource groups. For more information, see Use Resource Control to Achieve Resource Group Limitation and Flow Control.

Note:

This table is not available on {{{ .starter }}} and {{{ .essential }}} clusters.

USE information_schema;
DESC resource_groups;

+-------------+--------------+------+------+---------+-------+
| Field       | Type         | Null | Key  | Default | Extra |
+-------------+--------------+------+------+---------+-------+
| NAME        | varchar(32)  | NO   |      | NULL    |       |
| RU_PER_SEC  | varchar(21)  | YES  |      | NULL    |       |
| PRIORITY    | varchar(6)   | YES  |      | NULL    |       |
| BURSTABLE   | varchar(3)   | YES  |      | NULL    |       |
| QUERY_LIMIT | varchar(256) | YES  |      | NULL    |       |
| BACKGROUND  | varchar(256) | YES  |      | NULL    |       |
+-------------+--------------+------+------+---------+-------+
6 rows in set (0.00 sec)

Examples

SELECT * FROM information_schema.resource_groups; -- View all resource groups. TiDB has a `default` resource group.

+---------+------------+----------+-----------+-------------+------------+
| NAME    | RU_PER_SEC | PRIORITY | BURSTABLE | QUERY_LIMIT | BACKGROUND |
+---------+------------+----------+-----------+-------------+------------+
| default | UNLIMITED  | MEDIUM   | UNLIMITED | NULL        | NULL       |
+---------+------------+----------+-----------+-------------+------------+

CREATE RESOURCE GROUP rg1 RU_PER_SEC=1000; -- Create a resource group `rg1`

Query OK, 0 rows affected (0.34 sec)

SHOW CREATE RESOURCE GROUP rg1; -- Show the definition of the `rg1` resource group

+----------------+---------------------------------------------------------------+
| Resource_Group | Create Resource Group                                         |
+----------------+---------------------------------------------------------------+
| rg1            | CREATE RESOURCE GROUP `rg1` RU_PER_SEC=1000 PRIORITY="MEDIUM" |
+----------------+---------------------------------------------------------------+
1 row in set (0.00 sec)

SELECT * FROM information_schema.resource_groups WHERE NAME = 'rg1'; -- View the resource groups `rg1`

+------+------------+----------+-----------+-------------+------------+
| NAME | RU_PER_SEC | PRIORITY | BURSTABLE | QUERY_LIMIT | BACKGROUND |
+------+------------+----------+-----------+-------------+------------+
| rg1  | 1000       | MEDIUM   | OFF       | NULL        | NULL       |
+------+------------+----------+-----------+-------------+------------+
1 row in set (0.00 sec)

The descriptions of the columns in the RESOURCE_GROUPS table are as follows:

• NAME: the name of the resource group.

• RU_PER_SEC: the backfilling speed of the resource group. The unit is RU/second, in which RU means Request Unit.

• PRIORITY: the absolute priority of tasks to be processed on TiKV. Different resources are scheduled according to the PRIORITY setting. Tasks with high PRIORITY are scheduled first. For resource groups with the same PRIORITY, tasks will be scheduled proportionally according to the RU_PER_SEC configuration. If PRIORITY is not specified, the default priority is MEDIUM.

• BURSTABLE: whether to allow the resource group to overuse the available remaining system resources. Starting from v9.0.0, the following three modes are supported. If no value is specified for BURSTABLE, the MODERATED mode is enabled by default.

  • OFF: indicates that the resource group is not allowed to overuse any remaining system resources.
  • MODERATED: indicates that the resource group is allowed to overuse remaining system resources to a limited extent, with priority given to allocated resources within its quota.
  • UNLIMITED: indicates that the resource group can overuse remaining system resources without limitation, and the excess system resources are treated as equal to the resources within the quota during allocation.

Note:

TiDB automatically creates a default resource group during cluster initialization. For this resource group, the default value of RU_PER_SEC is UNLIMITED (equivalent to the maximum value of the INT type, that is, 2147483647) and its BURSTABLE mode is UNLIMITED. All requests that are not bound to any resource group are automatically bound to this default resource group. You cannot delete the default resource group, but can modify its RU configuration.