Redis introduction

1、Redis yes NoSQL A kind of database ,NoSQL(NoSQL = Not Only SQL ), meaning “ not only SQL”, A general term for a non-relational database . NoSQL It doesn't rely on business logic to store , In a simple way key-value Mode storage . Therefore, it is greatly increased The expansion ability of the database .

  Non compliance  SQL  standard . 
  I won't support it  ACID.
  Far beyond  SQL  Performance of .

2、 NoSQL Applicable scenario

  High concurrent reading and writing of data  
  Read and write massive data  
  High scalability of data 

3、NoSQL Not applicable to the scene

  Need transaction support  
  be based on  sql  Structured query storage of , Dealing with complex relationships , You need to make an ad hoc inquiry . 

 （ Not need sql And used sql It doesn't work , Please consider using NoSql

4、NOSQL The role of database
web2.0 Time ： Single server 、 Single database , Due to the increasing number of users ,CPU、 Memory and IO Are facing great pressure .

At this time redis It came into being .

（1） solve CPU And memory pressure
（2） solve IO pressure

5、redis brief introduction

Concrete NoSQL You can go to the official website to understand .