Horizontal scaling of tenant resources

Horizontal management of tenant resources is mainly achieved by dynamically adjusting the available resources of a tenant through modifying the UNIT_NUM of a resource pool. Specifically, you can adjust the UNIT_NUM of a resource pool to change the number of units in each zone under the resource pool, thereby increasing or decreasing the service capacity of the tenant in the corresponding zone.

OceanBase Database supports two zone deployment modes: homogeneous zone mode and heterogeneous zone mode:

• In homogeneous zone mode, the UNIT_NUM must be the same for all zones under a tenant.

• In heterogeneous zone mode, the UNIT_NUM can be the same or different across zones under a tenant, but a tenant can have at most two different UNIT_NUM values across all its zones.

Changes to UNIT_NUM fall into two categories: increasing UNIT_NUM and decreasing UNIT_NUM:

• For tenants deployed in homogeneous zone mode:

  • If a resource pool is not assigned to a tenant, you can increase or decrease the UNIT_NUM of that resource pool individually.

  • If a resource pool is already assigned to a tenant, you can only adjust the UNIT_NUM of all assigned resource pools simultaneously; individual adjustment is not supported.

• For tenants deployed in heterogeneous zone mode, you can adjust the UNIT_NUM regardless of whether the resource pool is assigned to a tenant. That is, you can either adjust the UNIT_NUM of all assigned resource pools simultaneously or increase or decrease the UNIT_NUM of a single resource pool individually.

Increasing or decreasing UNIT_NUM essentially means adding or removing units. The following examples show how to adjust the UNIT_NUM of a resource pool:

1. For a resource pool in heterogeneous zone mode, or for an unassigned resource pool in homogeneous zone mode, adjust the UNIT_NUM of the resource pool individually.

   Assume the resource pool to be adjusted is created as follows:

   obclient> CREATE RESOURCE POOL rp1 UNIT 'uc1', UNIT_NUM 2, ZONE_LIST ('zone1', 'zone2');
   

   Adjustment examples:

   obclient> ALTER RESOURCE POOL rp1 UNIT_NUM 3; // Increase UNIT_NUM
   

   obclient> ALTER RESOURCE POOL rp1 UNIT_NUM 2; // Decrease UNIT_NUM
   

   obclient> ALTER RESOURCE POOL rp1 UNIT_NUM 1 DELETE UNIT = (1001, 1003); // Decrease UNIT_NUM by deleting specified resource units
   

2. Adjust the UNIT_NUM of all resource pools of a tenant simultaneously.

   Assume the tenant's resource pools are created as follows:

   obclient> CREATE RESOURCE POOL rp2 UNIT 'uc1', UNIT_NUM 2, ZONE_LIST ('zone1', 'zone2');
   

   obclient> CREATE RESOURCE POOL rp3 UNIT 'uc1', UNIT_NUM 2, ZONE_LIST ('zone3');
   

   obclient> CREATE TENANT tt RESOURCE_POOL_LIST = ('rp2', 'rp3');
   

   Adjustment examples:

   obclient> ALTER RESOURCE TENANT tt UNIT_NUM = 3; // Increase UNIT_NUM for both resource pools
   

   obclient> ALTER RESOURCE TENANT tt UNIT_NUM = 1; // Decrease UNIT_NUM for both resource pools
   

Increase UNIT_NUM

• Example 1 for increasing UNIT_NUM:

  After you create a resource pool, you can increase the UNIT_NUM of a single resource pool individually.

  Assume the resource pool to be adjusted is created as follows:

  obclient> CREATE RESOURCE POOL r_p0 UNIT 'uc1', UNIT_NUM 2, ZONE_LIST ('zone1', 'zone2', 'zone3');
  

  For a resource pool in heterogeneous zone mode, or for an unassigned resource pool in homogeneous zone mode, use the following statement to increase the UNIT_NUM of the resource pool:

  obclient> ALTER RESOURCE POOL r_p0 UNIT_NUM 3;
  

• Example 2 for increasing UNIT_NUM:

  Increasing UNIT_NUM typically occurs in tenant scale-out scenarios. For example, for a resource pool that is already assigned to a tenant:

  obclient> CREATE RESOURCE POOL r_p0 UNIT 'uc1', UNIT_NUM 2, ZONE_LIST ('zone1', 'zone2', 'zone3');
  

  obclient> CREATE TENANT tt RESOURCE_POOL_LIST = ('r_p0');
  

  In this example, tenant tt uses resource pool r_p0. Each of zone1, zone2, and zone3 has 2 units. As the business volume grows, 2 units per zone can no longer support the current workload. Therefore, you need to increase UNIT_NUM to improve the service capacity of the tenant to meet the new business requirements.

  You can use the following statement to change the number of units in resource pool r_p0 to 3 for the tenant, thereby improving the tenant's service capacity:

  obclient> ALTER RESOURCE TENANT tt UNIT_NUM = 3;
  

Decrease UNIT_NUM

• Example 1 for decreasing UNIT_NUM:

  After you create a resource pool, you can decrease the UNIT_NUM of a single resource pool individually. Assume the resource pool to be adjusted is created as follows:

  obclient> CREATE RESOURCE POOL r_p0 UNIT 'uc1', UNIT_NUM 2, ZONE_LIST ('zone1', 'zone2', 'zone3');
  

  For a resource pool in heterogeneous zone mode, or for an unassigned resource pool in homogeneous zone mode, use the following statement to decrease the UNIT_NUM of the resource pool:

  obclient> ALTER RESOURCE POOL r_p0 UNIT_NUM 1;
  

  You can also decrease the UNIT_NUM of a single resource pool by deleting specified units. Use the following statement:

  obclient> ALTER RESOURCE POOL r_p0 UNIT_NUM 1 DELETE UNIT=(1001,1002,1003);
  

• Example 2 for decreasing UNIT_NUM:

  Decreasing UNIT_NUM typically occurs in tenant scale-in scenarios. For example, for a resource pool that is already assigned to a tenant:

  obclient> CREATE RESOURCE POOL r_p0 UNIT 'uc1', UNIT_NUM 2, ZONE_LIST ('zone1', 'zone2', 'zone3');
  

  obclient> CREATE TENANT tt RESOURCE_POOL_LIST = ('r_p0');
  

  In this example, tenant tt uses resource pool r_p0. Each of zone1, zone2, and zone3 has 2 units. As the business adjusts, 2 units per zone are no longer needed. Therefore, you need to decrease UNIT_NUM to meet the new business requirements.

  You can use the following statement to change the number of units in resource pool r_p0 to 1 for the tenant, thereby reducing the tenant's service capacity:

  obclient> ALTER RESOURCE TENANT tt UNIT_NUM = 1;
  

  Alternatively, in homogeneous zone mode, you can also decrease UNIT_NUM by deleting a specified UNIT_GROUP:

  obclient> ALTER RESOURCE TENANT tt  UNIT_NUM = 1 DELETE UNIT_GROUP =(1001);
  

References

• View tenant and resource information

• Scale out and in a tenant by adjusting the unit number