Design a Inventory Management for DoorDash
Last updated: July 3, 2025
Quick Overview
Design a multi-tenant inventory management system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
DoorDash
System Design
Software Engineer
DoorDash
July 3, 2025Software Engineer
Onsite
System Design
Hard
62
12
68 solved
Design a multi-tenant inventory management system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
System design interviews at DoorDash typically last 45-60 minutes. You are expected to drive the conversation, starting from requirements gathering through to a detailed architecture. The interviewer will evaluate your ability to handle ambiguity and make practical engineering decisions.
What the Interviewer Expects
- Drive the design discussion proactively with minimal interviewer guidance
- Perform detailed capacity estimation and use it to inform design decisions
- Design for global scale with multi-region deployment and data consistency
- Deep dive into 2-3 critical components with implementation-level detail
- Address complex trade-offs: CAP theorem, eventual consistency, conflict resolution
- Discuss operational excellence: deployment strategy, chaos engineering, SLOs/SLIs
- Propose a phased rollout plan from MVP to full-scale system
Key Topics to Cover
API design and rate limiting
Security and authentication
Requirements gathering and capacity estimation
Consistency models and replication
Monitoring, logging, and alerting
Partitioning and sharding strategies
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?
- How would you handle a region-wide outage?
- How do you ensure data consistency across multiple services?
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Requirements
Functional Requirements
- Multi-Tenant Architecture: Support multiple restaurants and stores as tenants, each managing their own inventory.
- Real-Time Inventory Updates: Allow restauran...
Capacity Estimation
Estimation Breakdown
- Active Tenants: Assume 10,000 active restaurants.
- Requests per Restaurant: Each restaurant makes an average of 100 requests per day (updates, queries).
- **Tota...
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