Why Single-Database Transactions Don’t Scale A transaction in a single database is simple. You start a transaction, make changes, commit. Either everything commits or nothing does. The database ha...

Why Replication Exists Your database will crash. Not maybe. It will. Hard drives fail, memory corrupts, someone runs the wrong command, power goes out. When that happens, you need another copy of ...

Introduction Most developers understand SQL. Fewer understand what happens after the query planner finishes — how rows are physically laid out on disk, why certain writes cost more than others, wh...

Introduction At some point you ship something that works perfectly in staging. The code is clean. The tests pass. You deploy it and feel good about it. Six months later you’re debugging a product...

The Real Cost - What happens when you don’t have idempotency Every backend engineer has experienced this: a user clicks a button, the request times out, they panic and click it again. Now somethin...

Why This Matters in Production Every backend engineer has a story about a production incident that made ACID properties real. Maybe it was a race condition in a payment system that took hours to t...

Introduction Your database has 50 million users. Someone searches by email. Without an index, the database reads every single row until it finds a match. That’s a full table scan — and it gets slo...