This topic describes the elastic scaling feature and its common use scenarios.

The elastic scaling feature of PolarDB allows you to dynamically scale your cluster. You do not need to lock databases when you change the specifications of your cluster. The elastic scaling feature supports the following three types of scaling, allowing you to change the specifications of your cluster within a few minutes:
  • Vertical scaling of the computing capacity: upgrade or downgrade the specifications of your cluster.
  • Horizontal scaling of the computing capacity: add or remove read-only nodes. A maximum of 16 computing nodes can be added.
  • Horizontal scaling of storage spaces: A serverless architecture is adopted. This allows the storage spaces to be automatically resized as the data volume changes. The maximum storage space for a single instance is 100 TB. If you need to store a large volume of data, we recommend that you purchase a storage plan to reduce costs. For more information, see Purchase a storage plan.
The elastic scaling feature supports the following scenarios:
  • Manually change specifications: You can manually change the specifications of your ApsaraDB PolarDB MySQL-compatible edition Cluster Edition instances. For more information about how to change the specifications, see Manually change specifications.
    Note Only ApsaraDB PolarDB MySQL-compatible edition Cluster Edition supports this scenario. Single Node and Archive Database editions do not support this scenario.
  • Automatically change specifications: You can configure the parameters of the automatic specification change feature. ApsaraDB PolarDB MySQL-compatible edition Cluster Edition instances automatically scale out and scale in based on the parameters that you configure. You can configure the parameters of the automatic specification change feature for ApsaraDB PolarDB MySQL-compatible edition clusters in two methods. For more information about the specific operations, see Enable the automatic specification change feature by using DAS and Automatic specification changes of the PolarDB for MySQL Cluster Edition.
    Note
    • Only ApsaraDB PolarDB MySQL-compatible edition Cluster Edition supports this scenario. Single Node and Archive Database editions do not support this scenario.
    • Only pay-as-you-go ApsaraDB PolarDB MySQL-compatible edition clusters support the automatic specification change feature. Subscription clusters do not support the feature.
  • Add and delete nodes: You can manually add or delete read-only nodes. For more information, see Add or remove read-only nodes.
    Note Only ApsaraDB PolarDB MySQL-compatible edition Cluster Edition supports this scenario. Single Node and Archive Database editions do not support this scenario.
  • Temporary upgrade: You can temporarily upgrade the specifications of your cluster to improve overall performance. When the specified restoration time is reached, the specifications of the cluster are automatically restored to those before the temporary upgrade. For more information, see Perform a temporary upgrade.
    Note
    • Only subscription PolarDB clusters support temporary upgrade.
    • Only ApsaraDB PolarDB MySQL-compatible edition Cluster Edition supports this scenario. Single Node and Archive Database editions do not support this scenario.