Redis6-01nosql database

1、NoSQL brief introduction

1.web1.0 :
2.web2.0:

3. solve CPU And memory pressure ：
4. solve IO pressure ：

2、NoSQL summary

NoSQL = Not Only SQL Non relational database
NoSQL It doesn't rely on business logic to store , In a simple way key-value Mode storage . Therefore, the expansion ability of the database is greatly increased .

• Non compliance SQL standard .
• I won't support it ACID. Atomicity 、 Uniformity 、 Isolation, 、 persistence
• Far beyond SQL Performance of .

Applicable scenario ：

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

Not applicable to the scene ：

• Need transaction support
• be based on sql Structured query storage of , Dealing with complex relationships , need Ad hoc inquiry .
• （ Not need sql And used sql It doesn't work , Please consider using NoSql）

3、 common NoSQL database

1、Memcache

 It's very early NoSql database

 The data is in memory , Generally not persistent

 Support simple key-value Pattern , Support type A single

 Usually as Cache database Secondary persistent database

2、Redis

 It's almost covered Memcached Most functions of

 The data is in memory , Support persistence , Mainly used for backup and recovery

 In addition to supporting simple key-value Pattern , And support Storage of multiple data structures , such as list、set、hash、zset etc. .

 Usually as Cache database Secondary persistent database

3、MongoDB

 High performance 、 Open source 、 Model freedom (schema free) The article of File database

 The data are all there Memory in , If there is not enough memory , Save infrequently used data to hard disk

 Although it is key-value Pattern , But yes. value（ In especial json） Provides rich query functions

 Support Binary data and large objects

 It can be replaced according to the characteristics of the data RDBMS , Become an independent database . Or cooperation RDBMS, Store specific data .