You can create custom cluster endpoints for ApsaraDB PolarDB PostgreSQL-compatible edition clusters. You can specify cluster endpoint settings, such as the read/write mode, the consistency level, and the 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 ApsaraDB PolarDB PostgreSQL-compatible edition cluster.

Procedure

  1. Log on to the PolarDB console.
  2. In the upper-left corner of the console, select the region where the cluster is deployed.
  3. Find the cluster and click the cluster ID.
  4. In the Endpoints section, click Create Custom Cluster Endpoint.
  5. In the Create Custom Cluster Endpoint dialog box, set the following parameters.
    Parameter Description
    Read/write Mode The read/write mode of the custom cluster endpoint. Available modes are Read Only and Read and Write (Automatic Read-write Splitting).
    Note You can change the read/write mode after you create the custom cluster endpoint. After you change the read/write mode, existing connections are closed. Make sure that your application can automatically reconnect to the cluster.
    Reader Nodes The nodes that you want to associate with the cluster endpoint to process read requests. You can select the nodes on the left side. Available nodes are the primary node and all the read-only nodes.
    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 create single-node endpoints. 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), available consistency levels are Eventual Consistency (Weak) and Session Consistency (Medium). For more information, see Consistency levels.
    • If you set Read/write Mode to Read Only, the default consistency level is Eventual Consistency (Weak) and cannot be changed.
    Primary Node Accepts Read Requests After this feature is enabled, SQL 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

  • How do I create a single-node endpoint?
    You can create a single-node endpoint only if the read/write mode of the cluster endpoint is set to Read Only and the cluster has at least three nodes. The reader nodes of the single-node endpoint can be only read-only nodes. For the detailed procedure, see Procedure.
    Warning 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 1 hour. We recommend that you do not create single-node endpoints in the production environment.
  • What is the maximum number of single-node endpoints that I can create for a 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 two single-node endpoints for two of the read-only nodes, one for each read-only node. Similar rules apply if your cluster has five or more nodes.

  • If a single-node endpoint is created for a read-only node, can the read-only node function as the new primary node during a failover in the event of a system exception?

    No, the read-only node that has a single-node endpoint configured cannot automatically function as the new primary node during a failover. However, you can manually preform a switchover to specify the read-only node as the new primary node. For more information, see Perform a switchover.

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

    A cluster can have a maximum of four cluster endpoints, one of which is the default cluster endpoint and the other three are custom cluster endpoints.

  • Can I modify a cluster endpoint?

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

  • Can I delete a cluster endpoint?

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

Related API operations

API Description
CreateDBClusterEndpoint Creates a custom cluster endpoint.
DescribeDBClusterEndpoints Queries cluster endpoints.