Design a Order Processing Service
Last updated: January 30, 2026
Quick Overview
Design a distributed order processing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Elastic
January 30, 202620
14
2,168 solved
Design a distributed order processing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
This is a common system design question asked during Onsite at Elastic. The interviewer expects you to demonstrate your ability to design large-scale distributed systems, make well-reasoned trade-offs, and communicate your thought process clearly. Elastic values engineers who can think about scalability from day one.
What the Interviewer Expects
- Clearly define functional and non-functional requirements
- Propose a reasonable high-level architecture with core components
- Choose appropriate data storage solutions with basic justification
- Discuss basic scaling strategies (horizontal scaling, caching)
- Identify potential bottlenecks and suggest simple solutions
Key Topics to Cover
How to Approach This
- Start by clarifying functional and non-functional requirements with the interviewer.
- Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
- Draw a high-level architecture first, then deep dive into 1-2 critical components.
- Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
- Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
- What would the deployment pipeline look like for this system?
- What happens if one of your database nodes goes down?
- How would you migrate from a monolithic to a microservices architecture?
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Requirements
Functional Requirements
- Order Creation: Users should be able to create orders with item details, quantities, and payment information.
- Order Status Tracking: Users should be able to t...
Capacity Estimation
Assuming Elastic has an average of 1 million orders per day, we can calculate the capacity requirements:
- Requests per Second: 1 million orders / 86400 seconds = ~11.57 requests per second (RPS)...
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