Data Storage

🟠 P1 — store events, not state; the append-only log as source of truth

🟠 P1 — Command Query Responsibility Segregation; separate read and write models

🟠 P1 — underrated staff-level signal; how to change schemas on a live system

🟠 P1 — the durability mechanism underlying every serious database

🟠 P1 — DDIA Ch3 deep knowledge; shows understanding of storage engine internals

🔴 P0 — the first data decision in every design; determines query flexibility, scaling, and consistency