- RDBMS — fixed schema, tables, rows, strong joins, ACID across the whole DB
- MongoDB — flexible schema, collections, documents, embedding instead of most joins
- MongoDB scales out (sharding) more naturally; RDBMS traditionally scales up
- Choose RDBMS for complex multi-table transactions; MongoDB for flexible, evolving, document-shaped data
MongoDB vs RDBMS
MongoDB trades the rigid schema and joins of relational databases for flexibility and horizontal scale.