PolarDB:Add or remove nodes

Limits

• A PolarDB cluster supports up to 15 read-only nodes.

• Keep at least one read-only node with the same specifications as the primary node to maintain high availability.

Billing

New nodes inherit the billing method of the cluster:

When you remove a node, billing stops immediately for pay-as-you-go nodes. For subscription nodes, you receive a refund for the unused portion. For details, see Configuration change fees and Compute node billing.

Storage fees are not affected by the number of compute nodes.

Before you begin

• Add or remove nodes only when the cluster has no ongoing configuration changes.

• Add or remove one node at a time to avoid errors. Removing multiple nodes simultaneously is supported but not recommended.

• Remove nodes during off-peak hours and make sure your application can automatically reconnect to the cluster after a brief interruption.

• If your application connects through the cluster endpoint, PolarDB automatically blocks the removed node — no application configuration changes are needed.

Add a read-only node

Read/write splitting connections established before you add a node do not automatically route requests to the new node. To include the new node in traffic distribution, restart your application to force new connections.

1. Log on to the PolarDB console. In the left-side navigation pane, click Clusters. In the upper-left corner, select the region of the cluster. In the cluster list, find the cluster.

2. Open the Add/Remove Node page using one of the following methods:

   • In the Actions column, click Add/Remove Node.

   • Click the cluster ID to go to the Basic Information page. In the Database Nodes section, click Add/Remove Node.

3. Select Add Node and click OK.

   

4. Click + Add Read-only Node. To add multiple nodes at once, click + Add a Read-only Node repeatedly.

5. Configure the Switching Time parameter:

   Option	Description
   Switch Now	The node is added as soon as the configuration change takes effect.
   Switch At	Select a time within the next 24 hours. The task completes within 30 minutes after the selected time. View or cancel the task on the Scheduled Tasks page. For details, see Scheduled tasks.

6. Review and confirm the terms of service, then click Buy Now.

Remove a read-only node

1. Log on to the PolarDB console. In the left-side navigation pane, click Clusters. In the upper-left corner, select the region of the cluster. In the cluster list, find the cluster.

2. Open the Add/Remove Node page using one of the following methods:

   • In the Actions column, click Add/Remove Node.

   • Click the cluster ID to go to the Basic Information page. In the Database Nodes section, click Add/Remove Node.

3. Select Delete Node and click OK.

   

4. Click the icon to the right of the node name to remove it.

5. Review and confirm the terms of service, then click Buy Now.

API reference