MongoDB: Overview

Documents

A record in MongoDB is a document, which is a data structure composed of field and value pairs.

document

• Field name
  Field names are strings.

• The _id Field
  In MongoDB, each document stored in a collection requires a unique _id field that acts as a primary key. If an inserted document omits the _id field, the MongoDB driver automatically generates an ObjectId for the _id field.

!Note: 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.

Collections

MongoDB stores documents in collections. Collections are analogous to tables in relational databases.

collections

Databases

In MongoDB, databases hold collections of documents.

BSON

MongoDB stores data records as BSON documents. BSON is a binary representation of JSON documents, though it contains more data types than JSON.

read more: BSON types

References

• MongoDB 基础系列二：数据结构

• MongoDB documentation: Introduction to MongoDB

• tutorialpoint: MongoDB Overview