MongoDB tracking and usage

MongoDB is an open-source, document-oriented NoSQL database that provides high performance, high availability, and easy scalability. It uses a flexible, JSON-like format called BSON for storing documents and allows for querying and indexing that data efficiently.

MongoDB ensures data durability using a write-ahead log (WAL) called the Journal. This journal keeps a record of all operations that alter the data. In case of a system failure or crash, MongoDB can recover data by applying the journal's operations to the dataset.

A replica set in MongoDB is a group of MongoDB instances that maintain the same data set. It consists of one primary node and multiple secondary nodes. The primary node is responsible for processing write operations, while secondary nodes replicate the data from the primary node. Replica sets provide redundancy, high availability, and automatic failover support for MongoDB deployments.

MongoDB achieves horizontal scaling via sharding, which is the process of distributing data across multiple servers. Sharding allows MongoDB to process queries and writes across multiple nodes in parallel, providing better performance and stability. It also allows the database to grow beyond the constraints of a single machine.

Embedded documents in MongoDB refer to storing related data in a single document as sub-documents, while references point to related data stored in other documents. Embedded documents are typically used when the related data is small and fits well within the parent document. References are used when the related data is large or needs to be shared among multiple parent documents.