You can create custom cluster endpoints for PolarDB-O clusters. When you create custom cluster endpoints, you can specify the read/write mode, consistency level, and associated read-only nodes to meet your business requirements and improve service flexibility. This topic describes how to create a custom cluster endpoint for a PolarDB-O cluster.

Procedure

  1. Log on to the PolarDB console.
  2. On the top of the page, select the region where the target cluster is located.
  3. Find the target cluster and click the cluster ID to go to the Overview page.
  4. In the Endpoints section, click Create Custom Cluster Endpoint.
    Create a custom cluster endpoint
  5. In the Create Custom Cluster Endpoint dialog box, set the following parameters.
    Parameter Description
    Read/write Mode Specifies the read/write mode for the custom cluster endpoint. Read Only and Read and Write (Automatic Read-write Splitting) are available.
    Note You can modify the read/write mode after you create the custom cluster endpoint. After you modify the read/write mode, existing connections to the cluster endpoint are closed. Make sure that your applications can automatically reconnect to the PolarDB-O cluster.
    Reader Nodes The nodes that you associate with the cluster endpoint to process read requests. You can select the primary node and read-only nodes in the Unselected Nodes section.
    Note
    • If you set Read/write Mode to Read and Write (Automatic Read-write Splitting), you must select at least two nodes, including the primary node.
    • If you set Read/write Mode to Read Only, you can select one or more nodes. You can also create a single-node endpoint to fit your needs. For more information, see FAQ.
    Automatically Associate New Nodes Specifies whether a new node is automatically associated with the cluster endpoint.
    Load Balancing Policy The policy for scheduling read requests among multiple read-only nodes if read/write splitting is enabled. The default value is Load-based Automatic Scheduling and cannot be changed.
    Consistency Level
    • If you set Read/write Mode to Read and Write (Automatic Read-write Splitting), the following consistency levels are available: Eventual Consistency and Session Consistency (Recommended). For more information, see PolarDB-O consistency levels.
    • If you set Read/write Mode to Read Only, the default consistency level is Eventual Consistency and cannot be changed.
    Offload Reads from Primary Node After this feature is enabled, SQL query statements are sent to only read-only nodes. This reduces the load on the primary node and ensures the stability of the primary node.
    Note You can configure this feature only after you set Read/write Mode to Read and Write (Automatic Read-write Splitting).
    Transaction Splitting Specifies whether to enable the transaction splitting feature. For more information, see Configure transaction splitting.
    Note You can configure this feature only after you set Read/write Mode to Read and Write (Automatic Read-write Splitting).
  6. Click OK.

FAQ

  • Q: How do I create a single-node endpoint?
    A: You can create one or more single-node endpoints only if Read/write Mode is set to Read Only and the cluster has at least three nodes. When you create single-node endpoints, you can only specify read-only nodes as reader nodes. The reader nodes are the backend nodes that process read requests. For more information, see Procedure.
    Warning However, if you create a single-node endpoint for a read-only node and the read-only node becomes faulty, the single-node endpoint may be unavailable for up to one hour. We recommend that you do not create single-node endpoints in your production environment.
  • Q: What is the maximum number of single-node endpoints that I can create in a cluster?

    A: The maximum number of the single-node endpoints that are allowed in a cluster varies based on the number of nodes in the cluster. If your cluster has three nodes, you can create a single-node endpoint for only one of the read-only nodes. If your cluster has four nodes, you can create a single-node endpoint for two of the read-only nodes, respectively. Similar rules apply if your cluster has five or more nodes.

  • Q: If a single-node endpoint is created for a read-only node, can the read-only node function as the new primary node after a failover?

    A: The read-only node that has a single-node endpoint configured cannot automatically function as the new primary node after a failover. However, you can manually specify the read-only node as the new primary node. For more information, see Switch workloads from writer nodes to reader nodes.

  • Q: What is the maximum number of cluster endpoints that a cluster can have?

    A: A cluster can have a maximum of four cluster endpoints. One is the default cluster endpoint and the other three are custom cluster endpoints.

  • Q: Can I modify a cluster endpoint?

    A: Yes, you can modify the default cluster endpoint and custom cluster endpoints. For more information, see Modify a cluster endpoint.

  • Q: Can I delete a cluster endpoint?

    A: Yes, you can delete a cluster endpoint. However, you can delete only custom cluster endpoints, and you cannot delete the default cluster endpoint. For more information, see Delete a custom cluster endpoint.

Related operations

API Description
CreateDBClusterEndpoint Creates a custom cluster endpoint for an Apsara PolarDB cluster.
DescribeDBClusterEndpoints Queries cluster endpoints for an Apsara PolarDB cluster.