Explain CQRS (Command Query Responsibility Segregation).
Updated Apr 28, 2026
Short answer
A pattern that separates read and update operations for a data store to optimize performance.
Deep explanation
As systems scale, maintaining consistency and resilience becomes harder. Patterns like Sagas manage distributed transactions without traditional locks. Circuit breakers prevent cascading failures by 'tripping' when a service is unhealthy, allowing it time to recover.
Real-world example
Netflix uses Hystrix/Resilience4j to ensure that if the 'Recommendations' service is slow, the user still sees their 'Watchlist'.
Common mistakes
- Implementing Sagas for every simple cross-service operation.
Follow-up questions
- What is a 'fallback' method?
- How do you handle data consistency in Sagas?