AdvancedTechnical
5 min
Database Deadlock Troubleshooting
DatabasesTroubleshootingSQL
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Interview Question
How would you detect, troubleshoot, and mitigate deadlocks in a relational database system?
Key Points to Cover
- Identify deadlocks using DB logs or monitoring tools
- Analyze lock waits and query execution plans
- Apply query/index optimization and consistent locking order
- Introduce retries with exponential backoff
- Use reduced isolation levels where safe
Evaluation Rubric
Explains how to detect deadlocks30% weight
Analyzes lock contention patterns30% weight
Suggests query/transaction optimizations20% weight
Provides prevention strategies20% weight
Hints
- 💡Think transaction isolation and lock order.
Common Pitfalls to Avoid
- ⚠️Failing to set up or regularly review deadlock logs and alerts.
- ⚠️Only looking at the deadlocked queries without considering the broader transaction context.
- ⚠️Ignoring the importance of index performance and its impact on lock duration.
- ⚠️Implementing transaction isolation levels without fully understanding their deadlock implications.
- ⚠️Not communicating or enforcing consistent locking order across development teams.
Potential Follow-up Questions
- ❓How do you log deadlocks in MySQL/Postgres?
- ❓How would you simulate them in staging?
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