Learn MongoDB in depth

NoSQL (not only SQL)
Why use NoSQL
High concurrency for database read and write
Efficient storage and access to massive amounts of data
High scalability and high availability for databases

The weakness of NoSQL
Database Transactional Consistency Requirements
The demand of realistic time and read real time of database
Multi-complex SQL queries, especially for multi-table associated queries

Four categories of NoSQL
Key-value Storage Typical Application scenario: content Caching
Typical application scenario for a column database: Distributed File systems
A typical application scenario for a document database: Web-based applications
Graph structure Database Typical application scenario: Social network, recommender system (graph structure)

MongoDB is a high-performance, open-source, modeless, document-based database that can replace relational databases in many scenarios.
MongoDB uses C + + development, does not support SQL, but has its own powerful query syntax,
MongoDB uses Bson as the data storage and transfer format, and Bosn (the extension of JSON) is a josn-like binary serialized document,
Nested objects and arrays are supported, and collection in MongoDB is much like table,document in SQL, much like row in SQL

MongoDB version naming specification: x.y.z y is an odd-numbered development version, Y is an even number for stable version

Learn MongoDB in depth