enable_rebalance

Description

enable_rebalance specifies whether to enable automatic load balancing.

This parameter controls different balancing operations for different tenants:

• In the sys tenant, this parameter specifies whether to enable tenant-level load balancing.

  • false: The system does not perform background unit migration. However, if a node is permanently offline or in the DELETING state, unit migration is not controlled by this parameter.
  • true: The system can perform unit migration to achieve load balancing.

• In a user tenant, this parameter specifies whether to enable automatic load balancing within the tenant.

  • false: The system does not perform load balancing within the tenant. Any ongoing load balancing operations are canceled. If you perform the following operations, an error is returned:

    • Increase or decrease the number of units in the tenant.
    • Change the primary zone with the highest priority. If the primary zone with the highest priority does not change, no error is returned.
    • Change the number of F replicas when the primary zone is set to RANDOM.

    Notice

    • Starting from V4.3.5 BP1, if you set enable_rebalance to false, no error is returned when the primary zone with the highest priority changes or the number of F replicas changes when the primary zone is set to RANDOM.
    • Although no error is returned after you set enable_rebalance to false, the system does not perform load balancing. You can perform the required changes in batches while enable_rebalance is set to false, and then enable automatic load balancing by setting enable_rebalance to true.

  • true: The system can perform load balancing within the tenant.

Privilege requirements

• Query the parameter

  You can use the SHOW PARAMETERS statement or query the GV$OB_PARAMETERS view to query this parameter in the sys tenant and all user tenants.

• Modify the parameter

  You can modify this parameter in the sys tenant and all user tenants.

Attributes

Examples

• Disable tenant-level and automatic load balancing.

  obclient> ALTER SYSTEM SET enable_rebalance = false tenant = all_user;
  

• Enable tenant-level load balancing only.

  obclient> ALTER SYSTEM SET enable_rebalance = true tenant='all_user';
  

• Disable tenant-level load balancing, and enable automatic load balancing.

  obclient> ALTER SYSTEM SET enable_rebalance = false tenant='all_user';
            ALTER SYSTEM SET enable_rebalance = true tenant='MYSQL';
  

References

• Scale in or out a tenant by changing the number of resource units
• Scale in or out a tenant by changing the primary zone
• Resource unit balancing
• enable_transfer