When the proxy type, specification, or deployment mode of the database proxy no longer fits your workload, you can modify the configuration to scale capacity or adjust redundancy. This topic describes how to change these settings in the ApsaraDB RDS console and by calling an API operation, and provides formulas to calculate the recommended proxy node specification.
Prerequisites
Before you begin, ensure that you have:
The database proxy feature enabled on your RDS instance. For more information, see Enable the database proxy feature
Usage notes
Changing the proxy type, specification, or deployment mode makes the database proxy unavailable for 30–120 seconds. Make sure your application is configured to automatically reconnect.
If you change the proxy type or specification multiple times within a short period, the system retains only the sessions from the original specification before the most recent change.
During a configuration change, you cannot migrate the database proxy across zones. You can increase or reduce the number of zones. If you increase the number of zones, the deployment mode is changed from Deployment mode 3 to Deployment mode 2 or Deployment mode 1. If you reduce the number of zones, the deployment mode is changed from Deployment mode 2 or Deployment mode 1 to Deployment mode 3. For more information, see Proxy deployment architecture.
When switching from dual-zone deployment (Zone A + Zone B) to single-zone deployment (Zone A), delete the proxy endpoint in Zone B first. For more information, see Manage database proxy endpoints.
The nearest access feature is supported only in Deployment mode 1 for dedicated proxies. To switch to a general-purpose proxy or change the deployment mode, disable nearest access first. For more information, see Configure the nearest access feature.
How proxy specifications work
Two formulas govern how proxy specifications and node counts relate:
Proxy specification = Sum of CPU cores across all proxy nodes in all zones. For example, if Zone A has 2 nodes × 1 CPU core and Zone B has 2 nodes × 2 CPU cores, the proxy specification is 1 × 2 + 2 × 2 = 6 CPU cores.
Number of proxy nodes = Proxy specification ÷ 2 (the unit specification per node is fixed at 2 CPU cores). For example, a 6-CPU-core proxy has 3 nodes.
Recommended specification per proxy node:
| Proxy type | RDS High-availability Edition | RDS Cluster Edition |
|---|---|---|
| General-purpose | (CPU cores of primary instance + CPU cores of all read-only instances) ÷ 4, rounded up | (CPU cores of primary node + CPU cores of all secondary nodes) ÷ 4, rounded up |
| Dedicated | (CPU cores of primary instance + CPU cores of all read-only instances) ÷ 8, rounded up | (CPU cores of primary node + CPU cores of all secondary nodes) ÷ 8, rounded up |
Example: An RDS High-availability Edition instance with a primary instance (8 CPU cores) and two read-only instances (4 and 6 CPU cores). For a dedicated proxy: (8 + 4 + 6) ÷ 8 = 3 CPU cores per proxy node.
Impact of deployment mode changes
ApsaraDB RDS for MySQL supports three deployment modes. Switching between modes changes the number of zones and proxy nodes as follows.
Deployment mode 1
Deployment mode 2
Deployment mode 3
| Change | Zone change | Proxy node change |
|---|---|---|
| Deployment mode 1 → Deployment mode 2 | Unchanged | Reduced: 1 node removed from each of Zone A and Zone B |
| Deployment mode 1 → Deployment mode 3 | A zone is removed. Retain the zone where the primary instance resides. | Reduced: 2 nodes removed from Zone B |
| Deployment mode 2 → Deployment mode 1 | Unchanged | Increased: 1 node added to each of Zone A and Zone B |
| Deployment mode 2 → Deployment mode 3 | A zone is removed. Retain the zone where the primary instance resides. | Unchanged: 1 node added to Zone A, 1 node removed from Zone B |
| Deployment mode 3 → Deployment mode 1 | A zone is added | Increased: Zone A unchanged, 2 nodes added to Zone B |
| Deployment mode 3 → Deployment mode 2 | A zone is added | Unchanged: 1 node removed from Zone A, 1 node added to Zone B |
Modify the database proxy configuration
Go to the Instances page. In the top navigation bar, select the region where your RDS instance resides. Find the instance and click its ID.
In the left-side navigation pane, click Database Proxy.
In the Basic Information section, click Modify Configuration.
In the dialog box that appears, configure the following parameters and click OK:
Parameter Description Proxy Type Select General-purpose or Dedicated. Dedicated proxies provide exclusive compute resources. For a comparison, see What are database proxies? Deployment Method Select the deployment mode. For the impact of each mode change, see Impact of deployment mode changes. Total Number of Nodes The total number of proxy nodes across all zones. Calculated as: proxy specification ÷ 2. Zone The zone or zones where proxy nodes are deployed. Changing this value affects the deployment mode. CPU Cores for Single Proxy Node The number of CPU cores per proxy node. For the recommended value, see How proxy specifications work. Update Time When to apply the change: immediately, or during the next maintenance window to avoid business disruption. In the Configurations Before and After Specification Change dialog box, verify the configuration and click OK.
API reference
| Operation | Description |
|---|---|
| ModifyDBProxyInstance | Modifies the database proxy settings of an instance |
| DescribeDBProxy | Queries details about the proxy nodes of an instance |