ALTER RESOURCE POOL

Purpose

The ALTER RESOURCE POOL statement is used to modify the attributes of a resource pool, including the UNIT, UNIT_NUM, and ZONE_LIST attributes.

Limitations and considerations

• When using the ALTER RESOURCE POOL statement to modify resource pool attributes, each statement can modify only one attribute at a time. If you want to modify two or more attributes from UNIT, UNIT_NUM, and ZONE_LIST, you must execute multiple statements.

• In earlier versions, OceanBase Database supported only homogeneous zone mode for tenants. In homogeneous zone mode, the number of units in each zone of a tenant must be the same. Starting from V4.2.5 BP5 (only for V4.2.5), OceanBase Database supports heterogeneous zone mode for tenants. In heterogeneous zone mode, the number of units in each zone of a tenant can be different, but a tenant can have at most two unit_num values. When you increase or decrease UNIT_NUM:

  • In heterogeneous zone mode, you can increase or decrease UNIT_NUM for a resource pool regardless of whether the resource pool is allocated to the tenant. You can use the ALTER RESOURCE POOL statement for this purpose.

    Notice

    By default, homogeneous zone mode is enabled for existing tenants or tenants upgraded to a later version. If you want to enable heterogeneous zone mode, you must set the zone_deploy_mode parameter to hetero (heterogeneous zone mode). After you modify the parameter, you cannot change it back to homo (homogeneous zone mode).

  • In homogeneous zone mode, if the resource pool is allocated to the tenant, you cannot use the ALTER RESOURCE POOL statement to modify it. Instead, you must use the ALTER RESOURCE TENANT statement. For more information about the ALTER RESOURCE TENANT statement, see ALTER RESOURCE TENANT.

Privilege requirements

Only the root user of the sys tenant (root@sys) can modify resource pools. Other tenants cannot modify resource pools.

Syntax

ALTER RESOURCE POOL pool_name
      UNIT [=] unit_name
    | UNIT_NUM [=] unit_num [DELETE UNIT = (unit_id_list)]
    | ZONE_LIST [=] ('zone_name' [, 'zone_name' ...]);

Parameters

Examples

• You cannot modify multiple attributes of the same resource pool at the same time. For example, the following statement simultaneously modifies the UNIT, UNIT_NUM, and ZONE attributes of pool1. The system returns an error when it is executed.

  obclient [oceanbase]> ALTER RESOURCE POOL pool1 UNIT='unit2', UNIT_NUM=1, ZONE_LIST=('zone1');
  ERROR 1235 (0A000): alter unit_num, resource_unit, zone_list in one cmd not supported
  

  In particular, when you decrease the value of UNIT_NUM, you can delete the specified units.

  obclient [oceanbase]> ALTER RESOURCE POOL pool1 UNIT_NUM=1 DELETE UNIT = (1002);
  

• Change the resource specification of pool1 to unit2.

  obclient [oceanbase]> ALTER RESOURCE POOL pool1 UNIT='unit2';
  

References

• View resource pools

• Modify resource pool properties