enable_rebalance

enable_rebalance specifies whether to enable automatic load balancing.

• If you set this parameter in the sys tenant, it specifies whether to enable load balancing across tenants.
• If you set this parameter in a user tenant, it specifies whether to enable load balancing within the tenant.

You can specify the parameter in different tenants to control different balancing operations:

• In the sys tenant

  • false: Units are not migrated in the background. However, when the node is permanently removed or in the DELETING state, unit migration is not controlled by the parameter.
  • true: Unit migration can be performed to achieve load balancing.

• In a user tenant

  • false: No more load balancing operations are performed within the tenant. Load balancing operations in progress are canceled. If a scaling operation, such as any of the following operations, is initiated when the value is set to false, an error is reported:
    • Change the number of units in the tenant.
    • Change the primary zone of the top priority.
    • Change the number of full-featured replicas when primary_zone is set to RANDOM.
  • true: Load balancing operations can be performed within the tenant.

Examples

• Disable both cross-tenant and intra-tenant load balancing:

  alter system set enable_rebalance = false tenant = ALL;
  

• Enable only cross-tenant load balancing:

  alter system set enable_rebalance = true tenant='SYS';
  

• Disable cross-tenant load balancing and enable intra-tenant load balancing:

  alter system set enable_rebalance = false tenant='SYS';
  alter system set enable_rebalance = true tenant='MYSQL';