NoSQL/Mongo

Database notes

Database

A physical container for collections. Each database gets its own set of files on the file system. A single MongoDB server typically has multiple databases.

Collection

A grouping of MongoDB documents. A collection is the equivalent of an RDBMS table. A collection exists within a single database. Collections do not enforce a schema. Documents within a collection can have different fields. Typically, all documents in a collection have a similar or related purpose.

Document

A record in a MongoDB collection and the basic unit of data in MongoDB. Documents are analogous to JSON objects but exist in the database in a more type-rich format known as BSON. Documents contain name-value pairs called fields.

Field

A name-value pair in a document. A document has zero or more fields. Fields are analogous to columns in relational databases.

JSON

JavaScript Object Notation. A human-readable, plain text format for expressing structured data with support in many programming languages. For more information, see http://www.json.org. Certain MongoDB tools render an approximation of MongoDB BSON documents in JSON format.

BSON

A serialization format used to store documents and make remote procedure calls in MongoDB. “BSON” is a portmanteau of the words “binary” and “JSON”. Think of BSON as a binary representation of JSON (JavaScript Object Notation) documents.

Projection

A document given to a query that specifies which fields MongoDB returns in the result set.