How do I approach System Design interview questions?

System Design questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master system design interviews.

What difficulty level is this interview question?

This is a hard difficulty System Design question, commonly asked during Onsite rounds at DoorDash.

What role is this question designed for?

This question is commonly asked for Software Engineer candidates at DoorDash during technical interviews.

Design donation database and failure handling

Quick Overview

This question evaluates a candidate's understanding of backend system design for payment workflows, including data modeling for donations and pledges, transactional integrity, asynchronous webhook reconciliation, and failure-recovery strategies, and it falls under the System Design domain.

System Design: Donations Platform with One-Time and Recurring Payments

Context

Design a backend for a donations platform that supports campaigns, one-time donations, and recurring donations. The platform uses a third-party payment gateway and must be resilient to failures, retries, and asynchronous webhooks.

Requirements

Model core entities: users, campaigns, pledges (donation intent), payments (charge attempts), receipts, refunds, audit logs, and reconciliation records.
Support both one-time and recurring donations (e.g., monthly), including scheduling and retries for failed payments.
Ensure atomicity and consistency when creating a pledge and initiating a payment.
Use idempotency keys, explicit status state machines, and outbox/queue patterns to integrate with a payment gateway.
Handle payment failures and retries end-to-end.
Support chargebacks/disputes and partial refunds.
Reconcile asynchronous gateway webhooks with internal state.
Provide key database tables with primary keys, foreign keys, and important indexes.
Outline the failure-handling logic and retry strategy.

Quick Overview

Requirements

Model core entities: users, campaigns, pledges (donation intent), payments (charge attempts), receipts, refunds, audit logs, and reconciliation records.

Support both one-time and recurring donations (e.g., monthly), including scheduling and retries for failed payments.

Ensure atomicity and consistency when creating a pledge and initiating a payment.

Use idempotency keys, explicit status state machines, and outbox/queue patterns to integrate with a payment gateway.

Handle payment failures and retries end-to-end.

Support chargebacks/disputes and partial refunds.

Reconcile asynchronous gateway webhooks with internal state.

Provide key database tables with primary keys, foreign keys, and important indexes.

Outline the failure-handling logic and retry strategy.

Design donation database and failure handling

Quick Overview

System Design: Donations Platform with One-Time and Recurring Payments

Context

Requirements

Solution

Submit Your Answer to Earn 20XP

Design donation database and failure handling

Quick Overview

System Design: Donations Platform with One-Time and Recurring Payments

Context

Requirements

Solution

Submit Your Answer to Earn 20XP