System Design Fundamentals

System design is about making trade-offs. There’s rarely a perfect solution — only appropriate ones given constraints.

The CAP Theorem

Any distributed system can guarantee at most two of:

flowchart TD
    CAP[CAP Theorem]
    CAP --> C[Consistency]
    CAP --> A[Availability]
    CAP --> P[Partition Tolerance]
    C --> CP["CP Systems (e.g. HBase, Zookeeper)"]
    A --> AP["AP Systems (e.g. Cassandra, CouchDB)"]

Key Concepts

• Horizontal scaling — add more machines
• Vertical scaling — add more power to existing machines
• Load balancing — distribute traffic evenly
• Caching — reduce latency and database load
• Sharding — split data across multiple databases

Further Reading

• Designing Data-Intensive Applications by Martin Kleppmann
• System Design Interview by Alex Xu