Data Monitoring / MySQL Monitoring
MySQL: Performance Schema instrumentation
A diagnostic table is empty although the workload is active. Check instruments, consumers and retained history capacity for the required event type.
Environment and inputs: MySQL 8.4 baseline; Performance Schema consumers, privileges and replication topology affect evidence availability.
Failure scenario
A diagnostic table is empty although the workload is active. Confirm the cause before choosing a fix.
Evidence to collect
Check instruments, consumers and retained history capacity for the required event type. Record the time, affected scope and a healthy comparison interval.
Fix the confirmed cause
Enable only the necessary supported instrumentation and verify collection overhead and coverage. Write the expected result first. Change one relevant setting at a time.
Check the result and hand over
Repeat the check for performance schema instrumentation using the same scope and a representative interval. Check that the symptom is resolved, expected records are present and downstream results are correct. If coverage, correctness or latency worsens, restore the recorded configuration through the agreed rollback process.
Scope and precautions
Prefer read-only access and limit queries to the relevant period or dataset. This example has not been tested on your systems. Test changes in an approved environment. Keep credentials and sensitive data out of shared evidence.