What is PostgreSQL database?

Its real advantage is that it will refuse to hold data that contradicts the rules you gave it. Foreign keys, uniqueness and check constraints are enforced by the database, so a bug in one part of the application cannot leave you with an order pointing at a customer who does not exist. Transactions mean a multi-step operation either fully happens or fully doesn't, and a JSONB column covers the parts of your data that genuinely have no fixed shape.

Two things bite in production. Queries that were instant on development data get slow once a table grows, because the index that was never needed at a thousand rows is essential at a million. And the number of simultaneous connections is limited, which matters when a serverless deployment opens a fresh connection per invocation — the answer there is a pooler, not a bigger database.