Change node specifications-PolarDB(PolarDB)-阿里云帮助中心

A PolarDB-X instance is a distributed cluster composed of multiple nodes. Each node handles tasks such as SQL routing, data merging, and aggregation. You can change the node specifications and storage space of an instance to meet business needs. For example, you can upgrade the specifications to handle higher QPS during peak hours, or downgrade them to save resources during off-peak hours.

Scaling methods

Instance specification changes include upgrades and downgrades. Each method supports both node specification changes and storage space adjustments.

Upgrade: Increase the specifications of CN (compute nodes) and DN (storage nodes), and expand storage capacity. After an upgrade, the instance can handle more traffic.
Downgrade: Decrease the specifications of CN (compute nodes) and DN (storage nodes), and reduce storage capacity. Downgrades help reduce costs.

Considerations

Changing instance specifications causes a transient disconnection between your application and the instance. Ensure your application has an automatic reconnection mechanism.
If you use persistent connections, new nodes added during an upgrade do not immediately receive traffic. We recommend restarting your ECS instances in phases. First, restart the instances that handle low traffic. After confirming that your services run as expected, restart the remaining ones. If you use Druid as the connection pool, see How to select a connection pool for your application for best practices.

Procedure

Log on to the PolarDB-X console.
In the top navigation bar, select the region where the instance is deployed.
On the Instances page, click the PolarDB-X 2.0 tab.
Find the target instance and, in the Actions column, click Upgrade or Downgrade.
On the Upgrade or Downgrade page:
1. Select the target node specifications and whether to change storage capacity.
  
  Note
  For Enterprise Edition instances, you can change the specifications of or Downgrade compute and data nodes. For Standard Edition instances, you can only change the specifications of or Downgrade data nodes.
2. Select a Switch Mode. You can choose to execute immediately or execute during a maintenance window.
Confirm the information and click Buy Now. After you complete the purchase, the instance status changes to Upgrading / Downgrading (if you selected immediate execution).