Source & Architecture
Scaling the Database: Indexes, Read Replicas, Caching, and Sharding — In That Order
The database is almost always the first thing to buckle under growth — and the first thing engineers over-engineer in a panic. A no-hype ladder for scaling the data layer: why you measure and add an index before touching hardware, how read replicas exploit the read/write asymmetry (and the replication-lag trap they bring), where caching helps and why invalidation is the hard part, and when you finally reach for partitioning and sharding — the one decision that is genuinely hard to undo.