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You can probably do system design on two Postgres tables

Vikram Bose · Staff Engineer · Platform 9 min read21 Mar 2026
You can probably do system design on two Postgres tables

Watch any whiteboard system-design session and you'll see candidates reach for Kafka in the first 60 seconds. Most of the time, the right answer is much smaller — and far more impressive to a senior interviewer. Here's how to argue for boring infrastructure without sounding lazy.

Why Postgres beats most 'distributed' choices below 10K writes/sec

Modern Postgres on a managed instance handles 5–20K writes per second comfortably. Most products never hit that ceiling. Adding a queue, a stream processor, and a NoSQL store before you have to is the engineering equivalent of buying a forklift to carry your groceries.

Two tables, one outbox, infinite reach

Job queue, notifications, audit log, retries, idempotency — all of it can ride on a single `events` table with a tiny outbox pattern. Postgres LISTEN/NOTIFY is enough for low-latency fanout. Add a worker that polls FOR UPDATE SKIP LOCKED, and you have a queue that never loses a message.

When you actually do need more

Real-time pricing, telemetry firehoses, multi-region active-active — yes, those need specialised systems. But before you reach for them, ask: can the same problem be solved with stronger schema and better indexes? It usually can.

How to argue for it in an interview

Don't say 'I would just use Postgres.' Say: 'Given the SLO and traffic profile, here's why a single Postgres primary with a read replica meets every requirement, and here's the migration path if scale 10x's.' Interviewers love the second version.

Written by Vikram Bose
Staff Engineer · Platform
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