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
ALTERRESOURCEGROUPIfExistsResourceGroupNameResourceGroupOptionList
IfExists
IFEXISTS
ResourceGroupName
IdentifierDEFAULT
ResourceGroupOptionList
DirectResourceGroupOptionResourceGroupOptionListDirectResourceGroupOptionResourceGroupOptionList,DirectResourceGroupOption
DirectResourceGroupOption
RU_PER_SECEqOptstringLitPRIORITYEqOptResourceGroupPriorityOptionBURSTABLEBURSTABLEEqOptBooleanQUERY_LIMITEqOpt(ResourceGroupRunawayOptionList)QUERY_LIMITEqOpt()QUERY_LIMITEqOptNULLBACKGROUNDEqOpt(BackgroundOptionList)BACKGROUNDEqOpt()BACKGROUNDEqOptNULL
ResourceGroupPriorityOption
LOWMEDIUMHIGH
ResourceGroupRunawayOptionList
DirectResourceGroupRunawayOptionResourceGroupRunawayOptionListDirectResourceGroupRunawayOptionResourceGroupRunawayOptionList,DirectResourceGroupRunawayOption
DirectResourceGroupRunawayOption
EXEC_ELAPSEDEqOptstringLitACTIONEqOptResourceGroupRunawayActionOptionWATCHEqOptResourceGroupRunawayWatchOptionDURATIONEqOptstringLit
ResourceGroupRunawayWatchOption
EXACTSIMILAR
ResourceGroupRunawayActionOption
DRYRUNCOOLDOWNKILL
BackgroundOptionList
DirectBackgroundOptionBackgroundOptionListDirectBackgroundOptionBackgroundOptionList,DirectBackgroundOption
DirectBackgroundOption
TASK_TYPESEqOptstringLit

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=()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。

另请参阅