Design a multi-tenant Inventory Management System
Last updated: February 25, 2026
Quick Overview
Design a multi-tenant inventory management system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Postmates
February 25, 2026213
13
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Design a multi-tenant inventory management system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Postmates asks this during the System Design Round to assess your architectural thinking. They want to see how you decompose a complex problem, choose appropriate technologies, and reason about failure modes. Strong candidates proactively discuss monitoring, alerting, and operational concerns.
What the Interviewer Expects
- Systematically gather requirements and estimate capacity (QPS, storage, bandwidth)
- Design a scalable architecture with clear component responsibilities
- Make well-reasoned database and caching decisions with trade-off analysis
- Address consistency vs availability trade-offs specific to the use case
- Discuss partitioning strategy, replication, and data modeling
- Cover failure handling, monitoring, and alerting strategies
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
- How would you implement rate limiting to protect the system?
- What monitoring and alerting would you set up on day one?
- How would you handle schema migrations with zero downtime?
- What happens if one of your database nodes goes down?
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Requirements
Functional Requirements
- Multi-Tenant Support: The system must accommodate multiple clients (e.g., restaurants and retailers) with isolated inventory management.
- **Real-Time Inventory Upd...
Capacity Estimation
Back-of-Envelope Calculations
- Requests Per Second (QPS):
- Assume 10,000 active clients.
- Each client makes an average of 10 requests/minute.
- Total QPS = (10,000 clients * 10 r...
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