Adding Read Replicas to a Replica Set Instance

Constraints

• The version of a replica set instance must be 3.4, 4.0, 4.2, 4.4 or 5.0.
• Nodes cannot be added to an instance that is being backed up.
• An instance cannot be deleted when one or more nodes are being added.

Precautions

• A maximum of five read replicas can be added to a replica set instance.

Procedure

1. Log in to the management console.
2. Click in the upper left corner and select a region and a project.
3. Click Service List. Under Database, click Document Database Service to go to the DDS console.
4. On the Instances page, click the replica set instance.
5. In the Node Information area on the Basic Information page, click Add Read Replicas.
6. On the Add Read Replicas page, specify Specifications, Node Class, Nodes, Parameter Template, and Delay, and click Next.

   Table 1 Parameter description

   Parameter	Description
   Read Replica Parameter Template	The parameters that apply to the read replicas of a replica set instance. After a node are created, you can change the parameter template of the node to bring out the best performance. NOTE:

7. On the displayed page, confirm the node configuration information.
   • If you need to modify your settings, click Previous to go back to the page for you to specify details.
   • If you do not need to modify your settings, click Submit to add nodes.

8. View the results.
   • When nodes are added, the status of the instance is Adding read replicas. The entire process takes about 15 minutes.
   • In the Node Information area, view the information about the nodes you added.
   • Choose More > View Delay in the Operation column to view the delay of the current node.