MongoDB: the database for structures that keep changing

MongoDB stores data as flexible documents rather than rows in rigid tables — and for certain application types that difference is decisive. A product catalog where every category carries different attributes, event logs with varied structures, content in multiple shapes: in the relational model these demand convoluted schemas; in MongoDB they are stored naturally, exactly as they look. We use it in projects with fluid data structures and in prototyping phases where the schema changes weekly, often alongside Node.js, where documents flow naturally through the entire application. Our position without diplomacy: MongoDB is not a universal replacement for relational databases. Accounting, inventory and everything requiring strict transactions and cross-entity reporting live better in PostgreSQL — misused, the document model produces systems that are painful to query. We choose by the nature of the data, not by fashion.