SQL vs NoSQL: Choosing a Database for a Booking System

The question that decides it

Can two writes touch the same record? If yes — seats, orders, balances — you want transactions. If no — analytics, catalogs, activity feeds — you can store documents and stay happy.

The query that settled it

Book a seat, atomically, or fail:

UPDATE seats
   SET status = 'LOCKED', locked_by = $1
 WHERE id = $2 AND status = 'FREE'
RETURNING id;
-- rows === 1 ? booked : taken

This is one statement in Postgres. In a document store, the same guarantee needs optimistic concurrency, a version field, and a retry loop in application code. Postgres wins for the booking core — not because NoSQL is bad, but because this problem is a transaction.

Where I would go NoSQL

Read-heavy, write-once data: the product catalog, search indexes, cached feed slices. There the flexible schema and horizontal scaling are genuinely better.

The honest takeaway

The choice is rarely "SQL or NoSQL". It is "transactional core, document edges" — and the boundary is drawn by the queries, not the hype.