MongoDB

MongoDB is a document-oriented NoSQL database designed for scalability and developer productivity. It stores data in flexible, JSON-like documents called BSON within collections, allowing documents in the same collection to have different fields and structures.

Core features include a rich query language with indexing, including compound and geospatial indexes, an aggregation framework for data processing, and support for replication and sharding. Replica sets provide high availability with automatic failover, while sharding enables horizontal scaling across multiple machines. The default storage engine is WiredTiger, with MMAPv1 support in older versions.

Data modeling in MongoDB centers on documents with a unique _id field. Relationships can be modeled by embedding related data within a document or by referencing other documents. The database uses BSON, a binary representation of JSON, which supports data types such as ObjectId, dates, and binary data. Since version 4.0 (and later with 4.2+), MongoDB supports multi-document ACID transactions, including across shards in supported configurations.

Clients access MongoDB through official drivers for many programming languages and through tools such as the mongosh shell and MongoDB Compass GUI. MongoDB Atlas is the managed cloud service for deployment, monitoring, and automated backups.

History and licensing: MongoDB originated in 2009 (initially under 10gen) as an open-source project. The server software is distributed under the Server Side Public License (SSPL), a license that has been the subject of debate within the open-source community.

Use cases include content management, real-time analytics, mobile and web applications, catalogs, and Internet of Things workloads.