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
- ResourceGroupRunawayOptionList
- DirectResourceGroupRunawayOption
- ResourceGroupRunawayWatchOption
- ResourceGroupRunawayActionOption
- BackgroundOptionList
- DirectBackgroundOption
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"
| "BACKGROUND" EqOpt '(' BackgroundOptionList ')'
| "BACKGROUND" EqOpt '(' ')'
| "BACKGROUND" 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
BackgroundOptionList ::=
DirectBackgroundOption
| BackgroundOptionList DirectBackgroundOption
| BackgroundOptionList ',' DirectBackgroundOption
DirectBackgroundOption ::=
"TASK_TYPES" EqOpt stringLit
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。
| 参数 | 含义 | 举例 |
|---|---|---|
RU_PER_SEC | 每秒 RU 填充的速度 | RU_PER_SEC = 500 表示此资源组每秒回填 500 个 RU。 |
PRIORITY | 任务在 TiKV 上处理的绝对优先级 | PRIORITY = HIGH 表示优先级高。若未指定则默认为 MEDIUM。 |
BURSTABLE | 允许对应的资源组超出配额后使用空余的系统资源。 | |
QUERY_LIMIT | 当查询执行满足该条件时，识别该查询为 Runaway Query 并执行相应的操作 | QUERY_LIMIT=(EXEC_ELAPSED='60s', ACTION=KILL, WATCH=EXACT DURATION='10m') 表示当执行时间超过 60 秒后识别为 Runaway Query，对该查询执行终止操作，并在 10 分钟内对同样的 SQL 直接执行终止操作。QUERY_LIMIT=() 或 QUERY_LIMIT=NULL 则表示不进行 Runaway 控制。具体参数介绍参见管理资源消耗超出预期的查询 (Runaway Queries)。 ｜ |
BACKGROUND | 后台任务相关的设置。具体参数介绍参见管理后台任务 | BACKGROUND=(TASK_TYPES="br,stats") 表示将备份恢复和收集统计信息相关的任务作为后台任务调度。 |
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 | QUERY_LIMIT | BACKGROUND |
+------+------------+----------+-----------+-------------+------------+
| rg1 | 100 | MEDIUM | NO | NULL | 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 | BACKGROUND |
+------+------------+----------+-----------+----------------------------------------------------------------+------------+
| rg1 | 200 | LOW | NO | EXEC_ELAPSED='1s', ACTION=COOLDOWN, WATCH=EXACT DURATION='30s' | NULL |
+------+------------+----------+-----------+----------------------------------------------------------------+------------+
1 rows in set (1.30 sec)
修改 default 资源组的后台任务 BACKGROUND 相关设置。
ALTER RESOURCE GROUP default BACKGROUND = (TASK_TYPES = "br,ddl");
Query OK, 0 rows affected (0.08 sec)
SELECT * FROM information_schema.resource_groups WHERE NAME ='default';
+---------+------------+----------+-----------+-------------+---------------------+
| NAME | RU_PER_SEC | PRIORITY | BURSTABLE | QUERY_LIMIT | BACKGROUND |
+---------+------------+----------+-----------+-------------+---------------------+
| default | UNLIMITED | MEDIUM | YES | NULL | TASK_TYPES='br,ddl' |
+---------+------------+----------+-----------+-------------+---------------------+
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。