Overview of MongoDB: Architecture, Features, and Storage Model

MongoDB is a product that sits between relational and non‑relational databases, offering the richest feature set among NoSQL systems and resembling relational databases the most. It stores data in a loosely structured, JSON‑like BSON format, enabling complex data types.

The most notable characteristic is its powerful query language, which is object‑oriented and can perform almost all single‑table relational queries, along with full indexing support.

Overall architecture:

Internal architecture:

Its key characteristics are high performance, easy deployment, and convenient data storage. Main functional features include:

Collection‑oriented storage, easy to store object‑type data.

Schema‑free design.

Dynamic query support.

Comprehensive indexing, including internal objects.

Rich query capabilities.

Replication and fault recovery.

Efficient binary storage for large objects such as videos.

Automatic fragmentation handling for cloud‑scale scalability.

Support for multiple languages: Ruby, Python, Java, C++, PHP, etc.

File storage format is BSON (an extended JSON).

Network‑accessible.

The term “collection‑oriented” means data is grouped into collections, each with a unique name and capable of holding an unlimited number of documents. Collections are analogous to tables in relational databases but do not require a predefined schema, allowing heterogeneous documents to coexist.

Documents are stored as key‑value pairs; keys are strings that uniquely identify a document, while values can be complex types. This storage form is called BSON (Binary Serialized Document Format).

MongoDB server can run on Linux, Windows, or macOS, supporting both 32‑bit and 64‑bit applications, with the default port 27017. Running on a 64‑bit platform is recommended because the maximum file size on 32‑bit is limited to 2 GB.

Data is stored in files (default path: /data/db ) and managed using memory‑mapped files for efficiency.