Creating a Proxy Instance for Read/Write Splitting

1. Log in to the TaurusDB console.
2. On the Instances page, click the TaurusDB for PostgreSQL instance name.
3. In the navigation pane, choose Database Proxy.
4. Click Create Proxy Instance.
5. On the displayed page, set required parameters and click Next.
   Figure 1 Creating a proxy instance
   

   Table 1 Parameter description

   Parameter	Description
   Proxy Instance Name	The name can consist of 4 to 64 characters and must start with a letter. Only letters (case-sensitive), digits, hyphens (-), and underscores (_) are allowed.
   Proxy Mode	You can select Read/Write or Read-only as needed. Read/Write: Write requests are only forwarded to the primary node. Read requests are forwarded to the selected nodes with fewer active connections. Read-only: All read requests are forwarded to the selected read replicas with fewer active connections.
   Routing Policy	Only Load balancing is supported. Read requests are assigned to nodes with fewer active connections.
   Reads Allowed on Primary	After Reads Allowed on Primary is enabled, read requests are distributed to the primary node and all read replicas.
   Proxy Instance Specifications	You can select the proxy instance specifications as needed. General-enhanced: 2 vCPUs | 4 GB, 4 vCPUs | 8 GB, and 8 vCPUs | 16 GB
   Associate New Nodes	After Associate New Nodes is enabled, new read replicas will be automatically associated with the proxy instance.
   Database Nodes	You need to select the nodes to be associated with the proxy instance for processing read requests.

6. Confirm the proxy instance configuration.
   • If you need to modify your settings, click Previous.
   • If you do not need to modify your settings, click Submit.

7. View the proxy instance and associated nodes.

   After the proxy instance creation is complete, you can view the created proxy instance on the Database Proxy page.

   Figure 2 Viewing the created proxy instance
   

   On the Database Proxy page, click the proxy instance name to go to the Basic Information page. In the lower part of the page, check database nodes associated with the proxy instance. You can move the pointer to a node name to view its details.

   Figure 3 Viewing information about nodes associated with a proxy instance
   

Ensure that the inbound and outbound rules allow access of the proxy address. The default port is 5432.

1. Log in to the TaurusDB console.
2. On the Instances page, click the instance name to go to the Basic Information page.
3. In the Network Information area, click the security group name under Security Group.
4. On the Inbound Rules tab, check whether access through port 5432 is allowed by default.
   Figure 4 Allowing access through port 5432
   

   If there is no such a rule, click Fast-Add Rule. In the displayed dialog box, select PostgreSQL (5432), set the inbound rule parameters, and click OK.

   Figure 5 Fast adding port 5432
   

   Table 2 Inbound rule parameters

   Parameter	Description
   Protocols and Ports	Select PostgreSQL (5432).
   Type	Select IPv4 or IPv6.
   Source	Used to match the source of an external request. The source can be: IP address: The source is a fixed IP address. You can enter or paste multiple IP addresses separated by commas (,). Each IP address represents a different security group rule. Single IP address: IP address/mask Example IPv4 address: 192.168.10.10/32 Example IPv6 address: 2002:50::44/128 IP address range in CIDR notation: IP address/mask Example IPv4 address range: 192.168.52.0/24 Example IPv6 address range: 2407:c080:802:469::/64 Any IP addresses 0.0.0.0/0 represents all IPv4 addresses. ::/0 represents all IPv6 addresses. Security group: The source is another security group. You can select a security group in the same region from the drop-down list. If there is instance A in security group A and instance B in security group B, and the inbound rule of security group A allows traffic from security group B, traffic is allowed from instance B to instance A. IP address group: The source is an IP address group. An IP address group is a collection of one or more IP addresses. You can select an available IP address group from the drop-down list. For IP address ranges and IP addresses with the same security requirements, you can use an IP address group to simplify management. If no IP address groups are available, create one by referring to Creating an IP Address Group.
   Action	A security group rule action. The value can be Allow or Deny. If Action is set to Allow, the rule allows the source addresses to access specified ports of the cloud servers within the security group. If Action is set to Deny, the rule blocks the source addresses from accessing specified ports of the cloud servers within the security group. Security group rules are matched first by priority and then by action. Deny rules take precedence over allow rules.
   Priority	Priority of the security group rule. The priority value ranges from 1 to 100. The default value is 1, which has the highest priority. The security group rule with a smaller value has a higher priority.
   Description	Supplementary information about the security group rule. This parameter is optional. The description can contain a maximum of 255 characters and cannot contain angle brackets (<>).

1. Check for the proxy address and port on the TaurusDB for PostgreSQL console.

   Click the TaurusDB for PostgreSQL instance name. In the navigation pane, choose Database Proxy. In the proxy instance list, check for the proxy address and port.

   Figure 6 Checking for the proxy address and port
   

2. Log in to an ECS.

   For details, see Logging In to a Linux ECS.

3. Run the following command and enter the password to connect to the TaurusDB for PostgreSQL instance through the proxy address:

   psql -h <hostIP> -p <port> -U <userName> -d <database>

   Table 3 Parameter description

   Parameter	Description
   <hostIP>	Proxy address obtained in 1.
   <port>	Port obtained in 1.
   <userName>	Username of the TaurusDB for PostgreSQL database administrator account. The default value is root.
   <database>	Database name. The default value is postgres.

   

   When you log in as a new user, the error message FATAL: No pool configured for database: "postgres", user: "***" may be displayed. To resolve this, the proxy instance's synchronization needs to be triggered. You can do this in two ways:

   • Wait up to the cache_refresh timeout (5 minutes by default) for automatic synchronization.
   • Manually reboot the proxy instance to trigger synchronization immediately.