WHAT IS MONGODB?

MongoDB is a document database that provides high performance, high availability, and easy scalability.

• Document Database

o Documents (objects) map nicely to programming language data types.

o Embedded documents and arrays reduce need for joins.

o Dynamic schema makes polymorphism easier.

• High Performance

o Embedding makes reads and writes fast.

o Indexes can include keys from embedded documents and arrays.

o Optional streaming writes (no acknowledgments).

• High Availability

o Replicated servers with automatic master failover.

• Easy Scalability

o Automatic sharding distributes collection data across machines.

o Eventually-consistent reads can be distributed over replicated servers.

• Advanced Operations

A MongoDB deployment hosts a number of databases. A database holds a set of collections. A collection holds a set of documents. A document is a set of key-value pairs. Documents have dynamic schema. Dynamic schema means that documents in the same collection do not need to have the same set of fields or structure, and common fields in a collection’s documents may hold different types of data.

See Document Structure and Data Modeling for more information

MongoDB Queries

Queries in MongoDB provides a set of operators to define how the find() method selects documents from a collection based on a query specification document that uses a combination of exact equality matches and conditionals using a query operator.