You can configure the parameters for automatic specification changes on the Basic Information page of your the ApsaraDB PolarDB MySQL-compatible edition cluster, the ApsaraDB PolarDB MySQL-compatible edition Cluster Edition instances automatically scale out or scale in based on the parameters that you configure. This topic describes how to configure the parameters for automatic specification changes on the Basic Information page of a the ApsaraDB PolarDB MySQL-compatible edition cluster.

Prerequisites

  • Only the ApsaraDB PolarDB MySQL-compatible edition Cluster Edition is supported. Single Node and Archive Database are not supported. For more information about the three editions of PolarDB for MySQL, see Product editions.
  • No tasks for specification changes for your PolarDB cluster are in the pending state.
  • Your the ApsaraDB PolarDB MySQL-compatible edition clusters are pay-as-you-go clusters. Subscription clusters do not support the automatic specification change feature.

Billing rules

For information about the pricing rules, see Configuration change fees.

Precautions

  • You can upgrade or downgrade the specifications of a cluster as a whole. You cannot upgrade or downgrade the specifications of individual nodes in the cluster.
  • Upgrading or downgrading the specifications of a cluster does not have any impact on the existing data in the cluster.
  • You may experience PolarDB service interruptions for a few seconds when you change specifications. During this time, you cannot perform some operations. We recommend that you change specifications during off-peak hours and make sure that your applications can automatically reconnect to the cluster.
  • In most scenarios, it takes more time to execute read-only requests than read and write requests. The time required to execute read-only requests may further increase when you change the specifications of a PolarDB cluster.

Procedure

  1. Log on to the PolarDB console.
  2. In the upper-left corner of the console, select the region where the cluster that you want to manage is deployed.
  3. On the Clusters page, find the cluster for which you want to configure the parameters for automatic specification changes and click the cluster ID.
  4. On the Overview page, click Settings in the upper-right corner of the Database Nodes section.
    Page settings
  5. In the dialog box that appears, specify the following parameters.
    Parameter Description
    Auto Scaling-out Specifies whether to enable the automatic scale-out feature.
    Observation Period If the CPU utilization is greater than or equal to the specified value during the observation period, PolarDB automatically adds nodes or upgrades the specification of your cluster after the observation period expires. This ensures that the cluster can handle the incoming read and write requests. For example, if the observation period is 5 minutes and the time required for an automatic scale-out operation is 10 minutes, you can check the result of the scale-out operation after 15 minutes.
    CPU Usage The threshold for triggering an automatic scale-out operation. If the CPU Usage is greater than or equal to the specified value, an automatic scale-out operation is triggered.
    Maximum Specification The upper limit of the cluster specification. After an automatic scale-out operation is triggered, the system upgrades the specification of your PolarDB cluster to the upper limit in small increments. For example, the specification can be upgraded from 4 cores to 8 cores, and then to 16 cores.
    Maximum Number of Read-only Nodes The maximum number of read-only nodes that the cluster can contain. After an automatic scale-out operation is triggered, the read-only nodes of the PolarDB cluster are added one by one until the upper limit is reached.
    Note The nodes that are automatically added are associated with the default endpoint of your cluster. If you use a custom endpoint, you must specify whether these nodes are automatically associated with the endpoint by using the Automatically Associate New Nodes parameter. For more information about Automatically Associate New Nodes, see Configure the PolarDB proxy.
    Auto Scaling-in Specifies whether to enable the automatic scale-in feature.
    Note After you turn on Automatic Scale-down/in, if the CPU utilization remains at less than 30% for more than 99% of the quiescent period, an automatic scale-in operation is triggered after the quiescent period ends. The specification of the PolarDB cluster are scaled in to the original specification in small increments.
    Quiescent Period The minimum interval between two automatic scale-in operations or two automatic scale-out operations. During a quiescent period, PolarDB continuously tracks whether the trigger conditions for an automatic scale-out or scale-in operation are met. During this period, automatic scale-out or scale-in operations are not triggered. If a quiescent period and an observation period end at the same time and the CPU utilization reaches the threshold value within the observation period, PolarDB automatically triggers the automatic scale-out operation.
  6. Click OK.