ALTER RESOURCE POOL
Function
ALTER RESOURCE POOL changes the Cgroup of a resource pool.
Precautions
Only SYSADMIN and VCADMIN users can modify resource pools.
Syntax
ALTER RESOURCE POOL pool_name
WITH ({MEM_PERCENT= pct |
CONTROL_GROUP="group_name" |
ACTIVE_STATEMENTS=stmt |
MAX_DOP = dop |
MEMORY_LIMIT='memory_size' |
io_limits=io_limits |
io_priority='io_priority'}
[, ... ]);
Parameter Description
pool_name
Specifies the name of a resource pool.
The name of the resource pool is the name of an existing resource pool.
Value range: a string. It must comply with the identifier naming convention.
group_name
Specifies the name of a Cgroup.
NOTE:- You can use either double quotation marks ("") or single quotation marks ('') in the syntax when setting the name of a Cgroup.
- The value of group_name is case-sensitive.
- If group_name is not specified, the string “Medium” will be used by default in the syntax, indicating the Medium Timeshare Cgroup under DefaultClass.
- If a database administrator specifies a Workload Cgroup under Class, for example, control_group set to class1:workload1, the resource pool will be associated with the workload1 Cgroup under class1. The level of the Workload Cgroup can also be specified. For example, control_group is set to class1:workload1:1.
- If a database user specifies the Timeshare Cgroup string (Rush, High, Medium, or Low) in the syntax, for example, control_group is set to High, the resource pool will be associated with the High Timeshare Cgroup under DefaultClass.
Value range: an existing Cgroup.
stmt
Specifies the maximum number of statements that can be concurrently executed in a resource pool.
Value range: numeric data ranging from –1 to 2147483647
dop
Specifies the maximum statement concurrency degree for a resource pool, equivalent to the number of threads that can be created for executing a statement.
Value range: numeric data ranging from 1 to 64
memory_size
Specifies the maximum memory size of a resource pool.
Value range: a string from 1 KB to 2047 GB
mem_percent
Specifies the proportion of available resource pool memory to the total memory or group user memory.
In multi-tenant scenarios, the value of mem_percent of group users or service users ranges from 1 to 100. The default value is 20.
In common scenarios, the value of mem_percent of common users is an integer ranging from 0 to 100. The default value is 0.
NOTE:
When both mem_percent and memory_limit are specified, only mem_percent takes effect.io_limits
Specifies the upper limit of IOPS in a resource pool.
The IOPS is counted by ones for column storage and by 10 thousands for row storage.
io_priority
Specifies the I/O priority for jobs that consume many I/O resources. It takes effect when the I/O usage reaches 90%.
There are three priorities: Low, Medium, and High. If you do not want to control I/O resources, use the default value None.
Examples
The example assumes that the user has created the class1 Cgroup and three Workload Cgroups under class1: Low, wg1, and wg2.
-- Create a resource pool.
openGauss=# CREATE RESOURCE POOL pool1;
-- Update a resource pool and set its Cgroup to a High Timeshare Workload Cgroup under DefaultClass.
openGauss=# ALTER RESOURCE POOL pool1 WITH (CONTROL_GROUP="High");
-- Update a resource pool and set its Cgroup to a Low Timeshare Workload Cgroup under class1.
openGauss=# ALTER RESOURCE POOL pool1 WITH (CONTROL_GROUP="class1:Low");
-- Update a resource pool and set its Cgroup to a wg1 Workload Cgroup under class1.
openGauss=# ALTER RESOURCE POOL pool1 WITH (CONTROL_GROUP="class1:wg1");
-- Update a resource pool and set its Cgroup to a wg2 Workload Cgroup under class1.
openGauss=# ALTER RESOURCE POOL pool1 WITH (CONTROL_GROUP="class1:wg2:3");
-- Delete the resource pool pool1.
openGauss=# DROP RESOURCE POOL pool1;