IntermediateScenario
10 min
Database Performance Degradation
DatabasePerformanceTroubleshootingMonitoring
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Interview Question
Your application's database response times have increased by 300% over the last hour. Users are complaining about slow page loads. How do you investigate and resolve this?
Key Points to Cover
- Check monitoring dashboards for patterns
- Examine database metrics: CPU, memory, disk I/O, connections
- Review slow query logs and current running queries
- Check for blocking/deadlocks
- Analyze recent deployments or configuration changes
- Scale vertically/horizontally if resource-bound
- Implement query optimization or caching
Evaluation Rubric
Takes immediate action to gather data20% weight
Follows systematic investigation approach30% weight
Identifies potential root causes30% weight
Proposes both immediate and long-term fixes20% weight
Hints
- 💡Start with what changed recently
- 💡Look at both application and database metrics
Common Pitfalls to Avoid
- ⚠️Jumping to conclusions or making changes without sufficient data and evidence from monitoring tools and logs.
- ⚠️Focusing solely on one layer of the stack (e.g., only the database or only the application code) without considering the full end-to-end transaction path and its dependencies.
- ⚠️Ignoring existing monitoring and alerting systems, or not having them adequately configured to provide the necessary visibility.
- ⚠️Implementing 'fixes' (e.g., adding indexes, changing configuration) in a production environment without proper testing, validation, and understanding of their potential impact.
- ⚠️Failing to collaborate effectively with other teams (e.g., development, infrastructure, network) whose expertise or insights might be critical to resolving complex cross-cutting performance issues.
Potential Follow-up Questions
- ❓How would you prevent this in the future?
- ❓What alerts would you set up?
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