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    ApsaraDB RDS:Modify the RCU scaling range

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    ApsaraDB RDS:Modify the RCU scaling range

    Last Updated:Mar 30, 2026

    When your serverless ApsaraDB RDS for PostgreSQL instance consistently hits its RCU ceiling during peak hours or you want to reduce idle costs, adjust the minimum and maximum RDS Capacity Units (RCUs) to match your actual workload. The system automatically scales within the range you set, so you pay only for what you use.

    How it works

    RCUs measure the compute capacity of a serverless RDS instance. The system scales RCUs up or down within your configured range based on real-time workload. You control the bounds — the system handles the rest.

    To determine whether you need to adjust the range, check the Database Capacity (RCUs per Second) metric on the Basic Information page of your instance. If the value consistently approaches the current maximum, increase the upper bound.

    Limits

    • Applies only to instances using the serverless billing method.

    • If the maximum is already set to 14, you cannot adjust the scaling range from the console. See FAQ for alternatives.

    Billing

    Adjusting the scaling range is free. You are charged based on actual RCU consumption. For pricing details, see Overview of serverless ApsaraDB RDS for PostgreSQL instances.

    Change the scaling range

    Note

    Changes take effect immediately and do not affect your workloads.

    1. Log on to the ApsaraDB RDS console and go to the Instances page. In the top navigation bar, select the region where your instance resides. Find the instance and click its ID.

    2. In the Configuration Information section, click Modify Scaling Settings.

    3. In the dialog box, set the Minimum and Maximum values in the RDS Capacity Units (RCUs) section. The minimum number of RCUs is 0.5. The maximum number of RCUs is 14. You can configure the parameters based on your business requirements.

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    4. Click OK.

    FAQ

    The maximum is already 14 RCUs but my workload needs more. What are my options?

    Switch the instance to the pay-as-you-go billing method, then upgrade to a larger instance type. For example, a dedicated instance on RDS High-availability Edition supports up to 104 CPU cores and 768 GB of memory. See Change the billing method from serverless to pay-as-you-go and Instance types.

    What's next

    • Automatic suspension: Configure the instance to suspend automatically when no connections are established, to reduce idle costs. See Configure the automatic start and stop feature.

    • Scaling policy: The default policy is Do Not Execute Forcefully, which avoids service interruptions. Switch to Execute Forcefully only when performance takes priority over availability. See Change the scaling policy of RCUs.

    • Scheduled RCU adjustment: RCU scaling normally completes within seconds. Cross-instance scaling may take 3 to 5 minutes. To guarantee capacity at specific times, configure scheduled tasks to pre-adjust RCUs. See Configure scheduled tasks to adjust the number of RCUs.

    • API: Call ModifyDBInstanceSpec to change the RCU range programmatically.

      Parameter Description Example
      DBInstanceId ID of the serverless RDS instance pgm-****
      PayType Billing method. Set to Serverless. Serverless
      Direction Specification change type. Set to Serverless. Serverless
      ServerlessConfiguration.MaxCapacity Maximum number of RCUs 14
      ServerlessConfiguration.MinCapacity Minimum number of RCUs 0.5

    References