Help Center > > User Guide> Working with RDS for PostgreSQL> Instance Management> Changing a DB Instance Class

Changing a DB Instance Class

Updated at: May 26, 2020 GMT+08:00


You can change the CPU or memory (instance class) of a DB instance as required. If the status of a DB instance changes from Changing instance class to Available, the change is successful.

  • A DB instance cannot be deleted while its instance class is being changed.
  • You can scale up or down the compute and memory capacity of PostgreSQL DB instances as required.


  1. Log in to the management console.
  2. Click in the upper left corner and select a region and a project.
  3. Click Service List. Under Database, click RDS. The RDS console is displayed.
  4. On the Instance Management page, locate the target DB instance and choose More > Change Instance Class in the Operation column.

    Alternatively, click the target DB instance to go to the Basic Information page. In the DB Information area, click Change in the Instance Class field.

  5. On the displayed page, specify the new instance class and click Next.

    Figure 1 Changing a DB instance class

    You can change the DB instance class as required.

    Changing the DB instance class will cause the DB instance to reboot. Select off-peak hours to avoid service interruption.

    DB instances in a DeC only support the general-enhanced instance class.

  6. Confirm the specifications.

    • If you need to modify your settings, click Previous.
    • For pay-per-use DB instances, click Submit.

      To view the cost incurred by the DB instance class change, choose Billing > My Orders in the upper right corner.

  7. View the DB instance class change result.

    Changing the DB instance class takes 5–15 minutes. During this period, the status of the DB instance on the Instance Management page is Changing instance class. After a few minutes, click the DB instance and view the instance class on the displayed Basic Information page to check that the change is successful.

    After the CPU or memory of a PostgreSQL DB instance is changed, the system will change the values of the following parameters accordingly:

    • shared_buffers
    • max_connections
    • maintenance_work_mem
    • effective_cache_size
    • effective_cache_size

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