The restart problem

Your bookstore API is feeling great. The team adds books all week. Then someone restarts the server for a config change. Every book is gone. The in-memory array starts empty every time. This is the moment every backend engineer learns the hard way that memory is not storage.

A database persists data to disk. It survives restarts, deploys, crashes, and the moment a junior accidentally runs Ctrl-C in the wrong terminal. It also gives you queries, constraints, and transactions you cannot fake with an array.

Postgres is the default choice for most backends in 2026. It is open source, mature, fast, and has every feature you will ever need: relational tables, JSON columns, full text search, transactions, constraints. It is also what most teams hire for. If you only learn one database, learn Postgres first.

Quiz: Quiz

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