Working with resource groups v16
Use these data definition language commands to create and manage resource groups.
Creating a resource group
Use the CREATE RESOURCE GROUP command to create a new resource group.
CREATE RESOURCE GROUP <group_name>;
Description
The CREATE RESOURCE GROUP command creates a resource group with the specified name. You can then define resource limits on the group with the ALTER RESOURCE GROUP command. The resource group is accessible from all databases in the EDB Postgres Advanced Server instance.
To use the CREATE RESOURCE GROUP command, you must have superuser privileges.
Parameters
group_name
The name of the resource group.
Example
This example creates three resource groups named resgrp_a, resgrp_b, and resgrp_c:
edb=# CREATE RESOURCE GROUP resgrp_a; CREATE RESOURCE GROUP edb=# CREATE RESOURCE GROUP resgrp_b; CREATE RESOURCE GROUP edb=# CREATE RESOURCE GROUP resgrp_c; CREATE RESOURCE GROUP
This query shows the entries for the resource groups in the edb_resource_group catalog:
edb=# SELECT * FROM edb_resource_group;
rgrpname | rgrpcpuratelimit | rgrpdirtyratelimit -----------+------------------+-------------------- resgrp_a | 0 | 0 resgrp_b | 0 | 0 resgrp_c | 0 | 0 (3 rows)
Modifying a resource group
Use the ALTER RESOURCE GROUP command to change the attributes of an existing resource group. The command syntax comes in three forms.
This form renames the resource group:
ALTER RESOURCE GROUP <group_name> RENAME TO <new_name>;
This form assigns a resource type to the resource group:
ALTER RESOURCE GROUP <group_name> SET <resource_type> { TO | = } { <value> | DEFAULT };
This form resets the assignment of a resource type to its default in the group:
ALTER RESOURCE GROUP <group_name> RESET <resource_type>;
Description
The ALTER RESOURCE GROUP command changes certain attributes of an existing resource group.
The form with the RENAME TO clause assigns a new name to an existing resource group.
The form with the SET resource_type TO clause assigns the specified literal value to a resource type. Or, when you specify DEFAULT, it resets the resource type. Resetting a resource type means that the resource group has no defined limit on that resource type.
The form with the RESET resource_type clause resets the resource type for the group.
To use the ALTER RESOURCE GROUP command, you must have superuser privileges.
Parameters
group_name
The name of the resource group to alter.
new_name
The new name to assign to the resource group.
resource_type
Specifies the type of resource to which to set a usage value.
value | DEFAULT
When value is specified, the literal value to assign to resource_type. Specify DEFAULT to reset the assignment of resource_type for the resource group.
Example
These examples show the use of the ALTER RESOURCE GROUP command:
edb=# ALTER RESOURCE GROUP resgrp_a RENAME TO newgrp; ALTER RESOURCE GROUP edb=# ALTER RESOURCE GROUP resgrp_b SET cpu_rate_limit = .5; ALTER RESOURCE GROUP edb=# ALTER RESOURCE GROUP resgrp_b SET dirty_rate_limit = 6144; ALTER RESOURCE GROUP edb=# ALTER RESOURCE GROUP resgrp_c RESET cpu_rate_limit; ALTER RESOURCE GROUP
This query shows the results of the ALTER RESOURCE GROUP commands to the entries in the edb_resource_group catalog:
edb=# SELECT * FROM edb_resource_group;
rgrpname | rgrpcpuratelimit | rgrpdirtyratelimit -----------+------------------+-------------------- newgrp | 0 | 0 resgrp_b | 0.5 | 6144 resgrp_c | 0 | 0 (3 rows)
Removing a resource group
Use the DROP RESOURCE GROUP command to remove a resource group.
DROP RESOURCE GROUP [ IF EXISTS ] <group_name>;
Description
The DROP RESOURCE GROUP command removes a resource group with the specified name.
To use the DROP RESOURCE GROUP command, you must have superuser privileges.
Parameters
group_name
The name of the resource group to remove.
IF EXISTS
Don't throw an error if the resource group doesn't exist. Instead, issue a notice.
Example
This example removes the resource group newgrp:
edb=# DROP RESOURCE GROUP newgrp; DROP RESOURCE GROUP
Assigning a process to a resource group
Use the SET edb_resource_group TO group_name command to assign the current process to a specified resource group:
edb=# SET edb_resource_group TO resgrp_b; SET edb=# SHOW edb_resource_group;
edb_resource_group -------------------- resgrp_b (1 row)
The resource type settings of the group take effect on the current process immediately. If you use the command to change the resource group assigned to the current process, the resource type settings of the newly assigned group take effect immediately.
You can include processes in a resource group by default by assigning a default resource group to roles, databases, or an entire database server instance.
You can assign a default resource group to a role using the ALTER ROLE ... SET command. For more information about the ALTER ROLE command, see the PostgreSQL core documentation.
You can assign a default resource group to a database by using the ALTER DATABASE ... SET command. For more information about the ALTER DATABASE command, see the PostgreSQL core documentation.
You can assign the entire database server instance a default resource group by setting the edb_resource_group configuration parameter in the postgresql.conf file:
# - EDB Resource Manager - #edb_max_resource_groups = 16 # 0-65536 (change requires restart) edb_resource_group = 'resgrp_b'
If you change edb_resource_group in the postgresql.conf file, reload the configuration file to make it take effect on the database server instance.
Removing a process from a resource group
Set edb_resource_group to DEFAULT or use RESET edb_resource_group to remove the current process from a resource group:
edb=# SET edb_resource_group TO DEFAULT; SET edb=# SHOW edb_resource_group;
edb_resource_group -------------------- (1 row)
To remove a default resource group from a role, use the ALTER ROLE ... RESET form of the ALTER ROLE command.
To remove a default resource group from a database, use the ALTER DATABASE ... RESET form of the ALTER DATABASE command.
To remove a default resource group from the database server instance, set the edb_resource_group configuration parameter to an empty string in the postgresql.conf file. Then, reload the configuration file.
Monitoring processes in resource groups
After you create resource groups, you can get the number of processes actively using these resource groups from the view edb_all_resource_groups.
The following are the columns in edb_all_resource_groups:
- group_name. Name of the resource group.
- active_processes. Number of active processes in the resource group.
- cpu_rate_limit. The value of the CPU rate limit resource type assigned to the resource group.
- per_process_cpu_rate_limit. The CPU rate limit that applies to an individual active process in the resource group.
- dirty_rate_limit. The value of the dirty rate limit resource type assigned to the resource group.
- per_process_dirty_rate_limit. The dirty rate limit that applies to an individual active process in the resource group.
Note
Columns per_process_cpu_rate_limit and per_process_dirty_rate_limit don't show the actual resource consumption used by the processes. They indicate how EDB Resource Manager sets the resource limit for an individual process based on the number of active processes in the resource group.
This example shows edb_all_resource_groups when resource group resgrp_a contains no active processes, resource group resgrp_b contains two active processes, and resource group resgrp_c contains one active process:
edb=# SELECT * FROM edb_all_resource_groups ORDER BY group_name;
-[ RECORD 1 ]-----------------+------------------ group_name | resgrp_a active_processes | 0 cpu_rate_limit | 0.5 per_process_cpu_rate_limit | dirty_rate_limit | 12288 per_process_dirty_rate_limit | -[ RECORD 2 ]-----------------+------------------ group_name | resgrp_b active_processes | 2 cpu_rate_limit | 0.4 per_process_cpu_rate_limit | 0.195694289022895 dirty_rate_limit | 6144 per_process_dirty_rate_limit | 3785.92924684337 -[ RECORD 3 ]-----------------+------------------ group_name | resgrp_c active_processes | 1 cpu_rate_limit | 0.3 per_process_cpu_rate_limit | 0.292342129631091 dirty_rate_limit | 3072 per_process_dirty_rate_limit | 3072
The CPU rate limit and dirty rate limit settings that are assigned to these resource groups are:
edb=# SELECT * FROM edb_resource_group;
rgrpname | rgrpcpuratelimit | rgrpdirtyratelimit -----------+------------------+-------------------- resgrp_a | 0.5 | 12288 resgrp_b | 0.4 | 6144 resgrp_c | 0.3 | 3072 (3 rows)
In the edb_all_resource_groups view, the per_process_cpu_rate_limit and per_process_dirty_rate_limit values are roughly the corresponding CPU rate limit and dirty rate limit divided by the number of active processes.