Assigning Read Weights

After read/write splitting is enabled, you can assign read weights as required.

Description

After read/write splitting is enabled, you can assign read weights for the primary node and read replicas.
The default read weight of the primary node is 0. The higher read weight the primary node is assigned, the more read requests it can process.
When the read weights of all nodes are 0, services are not affected. In this case, the primary node processes all read and write requests by default.
The weight of a read replica ranges from 0 to 1000.

After Associate New Nodes is enabled, new read replicas will be automatically associated with the current proxy instance. The default read weight of any new node is 100.
After a read replica is deleted, its weight is automatically removed while the weights of other read replicas remain unchanged.

Procedure

Log in to the management console.
Click in the upper left corner and select a region and project.
Click in the upper left corner of the page, choose Database > TaurusDB.
On the Instances page, click the instance name.
On the Database Proxy page, click the name of a proxy instance.
On the Basic Information page, click Assign Weight.
In the displayed dialog box, select nodes for which you want to assign weights on the left and assign the weights on the right.
- Different applications can connect to the TaurusDB instance through different proxy addresses. Read and write requests are forwarded to associated nodes. You can also add nodes to or remove nodes from proxy instances.
- In the read/write mode, all write requests are routed to the primary node, and read requests are routed to each node based on the read weights.
- In the read-only mode, only read requests can be routed to read replicas based on the read weights.
Example:

As shown in Figure 1, one TaurusDB instance has one primary node and three read replicas, and two proxy instances have been created.
- Proxy instance 1 is in the read/write mode. The primary node and read replica 1 are associated with proxy instance 1 and assigned with a read weight of 100 and 200, respectively. They process read requests in the ratio of 1:2, that is, the primary node processes 1/3 read requests and read replica 1 processes 2/3 read requests. Write requests are automatically routed to the primary node.
- Proxy instance 2 is in the read-only mode. Read replica 2 and read replica 3 are associated with proxy instance 2 and assigned with a read weight of 100 and 200, respectively. Read replica 2 and read replica 3 process read requests in the ratio of 1:2, that is, read replica 2 processes 1/3 read requests, and read replica 3 processes 2/3 read requests.
  Figure 1 Read/Write splitting in multi-proxy scenarios (weighted routing policy)