The diagnostics feature provides you with information about your database performance. This helps you identify performance issues.

Prerequisites

Database Autonomy Service (DAS) provides the diagnostics feature only for the following types of database instances:
  • The database instance that you want to manage is of one of the following types:
    • ApsaraDB RDS for MySQL instance
    • MyBase MySQL
    • Self-managed MySQL database
  • The database instance is connected to DAS. For more information, see Access instances.

Procedure

  1. Log on to the DAS console.
  2. In the left-side navigation pane, click Instance Monitoring.
  3. On the page that appears, click the ID of the database instance that you want to manage. The instance details page appears.
  4. In the left-side navigation pane, click Diagnostics.
  5. On the Diagnostics page, you can create diagnostic reports and view previous reports.

FAQ

  • Q: How are the thread usage, connection usage, and maximum number of threads of a session calculated?
    A: These metrics for ApsaraDB RDS for MySQL instances are calculated based on the following formulas:
    • Thread usage = Number of active threads/Maximum number of threads
    • Connection usage = Current number of connections/Maximum number of connections allowed by the instance type
    • Maximum number of threads = thread_pool_size × (thread_pool_oversubscribe + 1)
  • Q: Why does the thread usage exceed 100%?

    A: According to the formula for thread usage, when the number of active threads is greater than the maximum number of threads, the thread usage exceeds 100%. The thread pool implementation method of ApsaraDB RDS for MySQL does not limit the number of active threads. Therefore, the number of active threads may be greater than the maximum number of threads.

References

For more information about the automatic SQL diagnostics feature, see Cost-based SQL diagnostics engine.