System Design: Quora

Design a question-and-answer community with searchable posts, ranked answers, and personalized feeds. This case study models a Quora-like service; it does not document Quora’s current production architecture.

Introduction

A search engine retrieves existing material. A question-and-answer community also lets someone ask for an explanation that has not been written yet. Waiting for a response adds delay, and the quality of that response depends on the contributors. The following illustration compares these ways of seeking information.

The two approaches complement each other: a new community answer can later become searchable content. Our system therefore needs both a publishing workflow and a way to retrieve earlier discussions.

What is Quora?