System Design Interview: TikTok architecture with @sudocode

Summary

Key Points

• The system design focuses on building a short video platform similar to TikTok or Instagram Reels, emphasizing high availability, fault tolerance, and low latency for uploads and streaming. 0:58
• The platform is designed to serve 10 million daily active viewers and 100,000 creators, resulting in a read-to-write ratio of approximately 100:1, which influences storage and serving strategies. 5:26
• Video files are stored in Amazon S3, chosen for its reliability, scalability for large files, and seamless integration with Content Delivery Networks (CDNs) for global distribution. 12:16
• Video metadata is managed in a NoSQL key-value store like MongoDB for flexible schema and fast access, while user data is stored in a relational database like MySQL for ACID properties and structured relationships. 16:35
• An asynchronous, parallel processing pipeline converts uploaded videos into multiple formats and resolutions by splitting them into chunks, optimizing for diverse device compatibility and performance. 27:13
• Video distribution heavily relies on CDNs to cache and serve content from geographically closer locations, significantly reducing latency and enhancing fault tolerance through replication across regions. 32:31
• HTTPS is selected as the primary protocol for both video upload to the ingest engine and streaming to user devices, ensuring reliable and ordered data transport. 37:59
• The video ingestion process utilizes a queue to decouple upload requests from processing, ensuring system stability under high load and providing users with immediate acknowledgment. 42:14
• The architecture incorporates key engineering principles such as decoupling ingestion from processing, extensive data replication, and the use of specialized databases to achieve a scalable, highly available, and fault-tolerant system. 42:36