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
- ResourceGroupRunawayOptionList
- DirectResourceGroupRunawayOption
- ResourceGroupRunawayWatchOption
- ResourceGroupRunawayActionOption
AlterResourceGroupStmt ::=
"ALTER" "RESOURCE" "GROUP" IfExists ResourceGroupName ResourceGroupOptionList
IfExists ::=
('IF' 'EXISTS')?
ResourceGroupName ::=
Identifier
| "DEFAULT"
ResourceGroupOptionList ::=
DirectResourceGroupOption
| ResourceGroupOptionList DirectResourceGroupOption
| ResourceGroupOptionList ',' DirectResourceGroupOption
DirectResourceGroupOption ::=
"RU_PER_SEC" EqOpt stringLit
| "PRIORITY" EqOpt ResourceGroupPriorityOption
| "BURSTABLE"
| "BURSTABLE" EqOpt Boolean
| "QUERY_LIMIT" EqOpt '(' ResourceGroupRunawayOptionList ')'
| "QUERY_LIMIT" EqOpt '(' ')'
| "QUERY_LIMIT" EqOpt "NULL"
ResourceGroupPriorityOption ::=
LOW
| MEDIUM
| HIGH
ResourceGroupRunawayOptionList ::=
DirectResourceGroupRunawayOption
| ResourceGroupRunawayOptionList DirectResourceGroupRunawayOption
| ResourceGroupRunawayOptionList ',' DirectResourceGroupRunawayOption
DirectResourceGroupRunawayOption ::=
"EXEC_ELAPSED" EqOpt stringLit
| "ACTION" EqOpt ResourceGroupRunawayActionOption
| "WATCH" EqOpt ResourceGroupRunawayWatchOption "DURATION" EqOpt stringLit
ResourceGroupRunawayWatchOption ::=
EXACT
| SIMILAR
ResourceGroupRunawayActionOption ::=
DRYRUN
| COOLDOWN
| KILL
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. | |
QUERY_LIMIT | When the query execution meets this condition, the query is identified as a runaway query and the corresponding action is executed. | QUERY_LIMIT=(EXEC_ELAPSED='60s', ACTION=KILL, WATCH=EXACT DURATION='10m') indicates that the query is identified as a runaway query when the execution time exceeds 60 seconds. The query is terminated. All SQL statements with the same SQL text will be terminated immediately in the coming 10 minutes. QUERY_LIMIT=() or QUERY_LIMIT=NULL means that runaway control is not enabled. See Runaway Queries. |
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 | QUERY_LIMIT |
+------+------------+----------+-----------+-------------+
| rg1 | 100 | MEDIUM | YES | NULL |
+------+------------+----------+-----------+-------------+
1 rows in set (1.30 sec)
ALTER RESOURCE GROUP rg1
RU_PER_SEC = 200
PRIORITY = LOW
QUERY_LIMIT = (EXEC_ELAPSED='1s' ACTION=COOLDOWN WATCH=EXACT DURATION='30s');
Query OK, 0 rows affected (0.08 sec)
SELECT * FROM information_schema.resource_groups WHERE NAME ='rg1';
+------+------------+----------+-----------+----------------------------------------------------+
| NAME | RU_PER_SEC | PRIORITY | BURSTABLE | QUERY_LIMIT |
+------+------------+----------+-----------+----------------------------------------------------+
| rg1 | 200 | LOW | YES | EXEC_ELAPSED=1s, ACTION=COOLDOWN, WATCH=EXACT[30s] |
+------+------------+----------+-----------+----------------------------------------------------+
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.