← DoorDash Interview Insights

DoorDash·Software Engineer·Onsite - System Design / Architecture·Staff

StaffPrefer not to say
May 2026

Summary

Two heavy system design questions back to back at DoorDash, both with a lot of surface area. The scheduled job platform one felt manageable but the employee review system caught me off guard with how much HR domain knowledge it assumed.

Questions Asked (2)

Q1

Design a company-wide scheduled job platform (like cron) that can run workflows across services, with support for schedule management, dependency graphs, retries with backoff, idempotency, backfills, concurrency control, multi-tenant isolation, observability, and horizontal scalability. Walk through storage schemas, coordinator/worker architecture, and disaster recovery.

System DesignTechnical Trade-offsData Modeling
Author's notes

This one I actually felt okay about going in.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and scale, then propose a high-level architecture with a coordinator and worker pool, emphasizing reliability and multi-tenancy. Dive into storage schemas, dependency handling, and failure recovery, and discuss trade-offs at each decision point.

Pro tip: Anchor your design around idempotency and exactly-once semantics, as these are critical for reliable scheduled workflows and demonstrate deep understanding of distributed systems challenges.

1. Clarify Requirements and Scale

Ask about expected job volume, latency SLAs, tenant count, and workflow complexity to scope the design appropriately.

2. High-Level Architecture

Propose a coordinator service for scheduling and dependency resolution, and a worker pool for execution, with a message queue for decoupling.

3. Storage Schema Design

Outline tables for jobs, schedules, dependencies, executions, and tenants, considering indexing for efficient queries and isolation.

4. Reliability and Scalability

Explain retry policies with exponential backoff, idempotency keys, concurrency limits, and horizontal scaling of coordinators and workers.

5. Observability and Disaster Recovery

Describe monitoring, logging, tracing, and backup/restore strategies, including multi-region failover for high availability.

Key Points to Mention

  • Idempotency implementation via unique execution IDs and deduplication
  • Dependency graph resolution using topological sort or DAG scheduling
  • Backfill support through historical schedule replay and catch-up mechanisms
  • Multi-tenant isolation using namespace-based resource quotas and access controls
  • Concurrency control with distributed locks or token buckets per tenant/job
  • Disaster recovery with cross-region replication and automated failover

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.

Q2

Design an employee review and rewards system that handles performance reviews, peer feedback, reward points and grants, approval workflows, audit trails, and privacy. Cover service boundaries, data models, HRIS and payroll integrations, and how you'd prevent abuse or fraud.

System DesignData ModelingAPI & Integrations
Author's notes

Rough.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and scale, then propose a microservices architecture with clear boundaries for reviews, feedback, rewards, and workflows. Detail the data models, integration points with HRIS and payroll, and mechanisms for audit, privacy, and fraud prevention, ensuring consistency and security.

Pro tip: Emphasize idempotency and eventual consistency in reward grants to prevent duplicate points, and discuss how to handle cross-service transactions with sagas or outbox patterns.

1. Clarify Requirements and Scale

Ask about scale (number of employees, reviews per cycle), compliance needs (GDPR, SOX), and integration constraints. Define functional and non-functional requirements.

2. Define Service Boundaries and Data Models

Propose microservices for reviews, peer feedback, rewards, workflow, and audit. Outline core entities like Employee, Review, Feedback, RewardAccount, Grant, and ApprovalRequest, with relationships and storage choices.

3. Design Integrations and Workflows

Describe how to sync with HRIS (e.g., Workday) for employee data and payroll for reward payouts. Design approval workflows using a state machine or workflow engine, ensuring idempotency and error handling.

4. Address Audit, Privacy, and Security

Implement immutable audit logs for all actions, role-based access control, and data encryption. Ensure privacy by anonymizing peer feedback and complying with regulations.

5. Prevent Abuse and Fraud

Introduce rate limiting, anomaly detection, and validation rules (e.g., peer feedback only from teammates). Use idempotent reward grants and manual review for suspicious activities.

Key Points to Mention

  • Microservices architecture with bounded contexts for reviews, feedback, rewards, and workflows
  • Data models: Employee, Review, Feedback, RewardAccount, Grant, ApprovalRequest, AuditLog
  • Integration patterns: HRIS sync via APIs/webhooks, payroll batch processing, idempotent operations
  • Approval workflows using state machines (e.g., pending, approved, rejected) with notifications
  • Audit trails: append-only logs, event sourcing, and compliance with SOX/GDPR
  • Fraud prevention: rate limiting, anomaly detection, peer validation, and manual review

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.