When your database instance encounters a failure or performance issue, use the Diagnostics feature to quickly analyze its performance over a specified time period. This provides a comprehensive overview of the database's health and helps you quickly identify the root cause of anomalies.
Prerequisites
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The target database engine is one of the following:
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ApsaraDB RDS for MySQL
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ApsaraDB MyBase for MySQL
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self-managed MySQL database
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The target database instance has been added to Database Autonomy Service (DAS). For more information, see Add a database instance to DAS.
Procedure
Log on to the DAS console.
In the navigation pane on the left, click .
Find the target instance and click the instance ID to open the instance details page.
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In the left-side navigation pane, click Diagnostics.
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On the Diagnostics page, you can create a diagnostic task and view historical diagnostic reports.
To switch between versions, click Go to Old Version or Go to New Version.
FAQ
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Q: In Diagnostics, how are thread usage, connection usage, and maximum number of threads calculated for a session?
A: For ApsaraDB RDS for MySQL, the formulas are as follows:
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thread usage = number of active threads / maximum number of threads
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connection usage = current number of connections / maximum number of connections allowed by the instance type
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maximum number of threads = thread_pool_size * (thread_pool_oversubscribe + 1)
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Q: Why does thread usage sometimes exceed 100%?
A: According to the formula, thread usage exceeds 100% when the number of active threads surpasses the maximum number of threads. The thread pool for ApsaraDB RDS for MySQL does not strictly limit the number of active threads.
Learn more
For a detailed technical overview of automatic SQL diagnosis, see Cost-based SQL diagnostic engine.