To enhance user experience, we have adjusted the default Buffer Pool size for certain specifications of ApsaraDB RDS for MySQL instances starting from June 25, 2025, Singapore Time. The adjustment varies depending on the specification type, with a change range of 5%-15%. Below are the relevant details and explanations:

Change Time: June 25, 2025, 00:00 (GMT+8)

Scope of Impact:

• New Instances: New instances created after the change time have automatically applied the new Buffer Pool settings.
• Existing Instances: Instances created before the change time fall into two categories:
  • Custom Configured Instances: Instances where the Buffer Pool has been manually adjusted are not affected and these instances continue to use your custom settings.
  • Default Settings Instances: Instances that have not customized the Buffer Pool and are using default settings will automatically apply the new settings when changing instance specifications or during a primary-secondary switch. Therefore, some of these instances may have already adopted the new values.

Impact and Explanation:

• Performance Improvements/User Benefits
  • For scenarios where the Buffer Pool hit rate is below 80%, performance improvements could range from 10% to 30% or higher, depending on the instance workload.
  • For scenarios with a hit rate between 80% and 95%, the performance increase could be between 5% to 15%.
  • For scenarios with a hit rate above 95%, the performance improvement will be relatively small.
• User Risks
  • Once the instance applies the new Buffer Pool settings, memory usage will increase slightly (within 10%). If the instance's daily memory usage is already high (above 80%), this change may trigger memory alerts during sudden spikes in traffic but will not directly cause out-of-memory (OOM) situations. We recommend monitoring your instance's resource information, paying attention to memory usage, and adjusting configurations as needed to avoid risks.

Recommendations:

• If you wish to manually change the Buffer Pool size, please refer to Change the Size of the InnoDB Buffer Pool >

We encourage you to assess how this change may impact you based on the information provided and take appropriate action as necessary.

If you have any questions or need support, please feel free to contact us via a support ticket.