Modifying the Routing Policy for a Proxy Instance

Working Principles of the Routing Policy

There are weighted and load balancing routing policies.

• Weighted: Read requests are assigned to nodes based on the weights you specify.
• Load balancing: Read requests are assigned to nodes with fewer active connections. In load balancing policy, you do not need to configure the weights of nodes.

Figure 1 Working principles of the routing policy

Example:

As shown in the preceding figure, a GaussDB(for MySQL) instance contains one primary node and four read replicas.

For the database proxy instance 1, the routing policy is weighted and the selected nodes include the primary node, read replica R1, and a read replica R2, with their read weight ratio of 0:70:80. The write requests of the Application A are automatically forwarded to the primary node through the proxy instance, and the read requests are routed to read replicas R1 and R2 in the ratio of 7:8.

For the database proxy instance 2, the routing policy is load balancing and the selected nodes include the primary node, read replica R3, and read replica R4. The proxy instance determines the node to which the read requests are forwarded based on the number of real-time active connections.

When there are many active connections in read replica R4, the proxy instance forwards most read requests to read replica R3 and the primary node to offload the pressure of the read replica R4.

Constraints

• To use the load balancing policy, the kernel versions of proxy instances must be 2.22.07.000 or later. To upgrade a kernel version, see Upgrading the Kernel Version of a Proxy Instance.

Procedure

1. Log in to the management console.
2. Click in the upper left corner and select a region and project.
3. Click in the upper left corner of the page, choose Databases > GaussDB(for MySQL).
4. On the Instances page, click the target DB instance name to go to the Basic Information page.
5. In the navigation pane on the left, choose Database Proxy.
6. On the Database Proxy page, click the name of a proxy instance.
7. On the Basic Information page, click Configure next to Routing Policy.
8. In the displayed dialog box, configure required parameters.
   Figure 2 Changing the routing policy of a proxy instance
   

   Table 1 Parameter description

   Parameter	Description
   Routing Policy	Weighted: Read requests are assigned to nodes based on the weights you specify. Load balancing: Read requests are assigned to nodes with fewer active connections. In load balancing policy, you do not need to configure the weights of nodes.
   Associate New Nodes	After this function is enabled, new read replicas will be automatically associated to the current proxy instance. If Routing Policy is Weighted, you need to configure read weights for the new nodes. The default weight of a node is 100. Nodes with higher weights process more read requests.
   Database Nodes	The proxy mode of a proxy instance affects read requests assigned to different nodes. Read-only mode: All read requests are assigned to the selected, but not to the primary node. Figure 3 Read-only mode Read/write mode: All read requests are assigned to the selected nodes (including primary nodes and read replicas) based on the routing policy. Figure 4 Read/Write mode

APIs

Changing the Routing Policy of a Proxy Instance