Design a real-time Data Pipeline System
Last updated: August 5, 2025
Quick Overview
Design a real-time data pipeline system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
DoorDash
August 5, 202523
8
4,972 solved
Design a real-time data pipeline system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
DoorDash asks this during the Technical Screen 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 handle a 10x increase in traffic overnight?
- How would you handle schema migrations with zero downtime?
- How do you ensure data consistency across multiple services?
- How would you migrate from a monolithic to a microservices architecture?
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Requirements
Functional Requirements
- Real-time Data Ingestion: The system should handle real-time ingestion of data from various sources including user orders, restaurant updates, and delivery status ch...
Capacity Estimation
To estimate capacity, consider the following:
- Daily Active Users (DAU): Assume 10 million users.
- Average Orders per User per Day: Assume 3 orders.
- Total Daily Orders: 10 million user...
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