MongoDB Introduction

MongoDB is a NoSQL database that stores data as flexible documents (JSON-like) instead of rigid tables and rows. It's a natural fit for JavaScript apps and evolving data.

Documents and collections

Documents live in collections. Unlike SQL tables, documents in one collection don't have to share the same fields — so your data shape can grow and vary without migrations.

{ "name": "Asha", "email": "asha@x.com", "roles": ["admin"] }
{ "name": "Ravi", "phone": "555-0100" }   // different fields, same collection

SQL vs MongoDB terms

When MongoDB fits

• Flexible or rapidly-changing schemas.
• Naturally nested/hierarchical data (a document = one object).
• High write throughput and easy horizontal scaling (sharding).
• For highly relational data with complex joins and strict integrity, a SQL database (PostgreSQL) is often a better fit.