What are the differences between redis and mysql?

The difference analysis is as follows:

(Learning video sharing: redis database tutorial)

1. Mysql and redis databases Type

mysql is a relational database, mainly used to store persistent data. The data is stored on the hard disk and the reading speed is slow.

redis is NOSQL, which is a non-relational database and a cache database. It stores data in the cache. The cache has fast reading speed and can greatly improve operating efficiency, but the storage time is limited

2. The operating mechanism of mysql

As a relational database with persistent storage, the relative weakness of mysql is that every time a request is made to access the database, there are I/O operations. If the database is accessed repeatedly and frequently. First: it will take a lot of time to repeatedly connect to the database, resulting in too slow operating efficiency; second: repeated access to the database will also cause the database load to be too high, so the concept of caching is derived at this time.

3. Cache

The cache is the buffer (cache) for data exchange. When the browser performs a request, it will first search in the cache. If it exists, it will be obtained; otherwise, it will be retrieved. Access the database.

The benefit of caching is fast reading speed

4. redis database

The redis database is a cache database used to store frequently used data, thus reducing access to the database times to improve operating efficiency.

5. Summary of the differences between redis and mysql

(1) In terms of type

In terms of type, mysql is a relational database and redis is a cache database

(2) Function

mysql is used to store data persistently on the hard disk. It is powerful but slow.

redis is used to store frequently used data in the cache. Fast reading speed

(3) Requirements

Mysql and redis are generally used together due to different requirements.

Supplement:
Redis and mysql should be selected according to specific business scenarios

mysql: data is placed on disk redis: data is placed in memory

redis is suitable for some Frequently used and relatively hot data, because it is stored in the memory, the read and write speed is very fast. It is generally used in the following scenarios

Rankings, counters, message queue push, friend attention, fans

First of all, you must know that mysql is stored in the disk, and redis is stored in the memory. Redis can be used for both persistent storage and caching. At present, most companies' storage is mysql redis, with mysql as the main storage. Redis is used as auxiliary storage for cache, speeding up access and reading, and improving performance
So why not just use redis for storage?
My opinion is: because redis is stored in memory, if it is stored in memory, the storage capacity must be much less than that of a disk. If you want to store a large amount of data, you can only spend more money to buy memory, resulting in some problems. It is relatively wasteful where high performance is not required, so currently it is basically mysql (primary) and redis (auxiliary). Redis is used where performance is required, and mysql is used where high performance is not required. Good steel is used on the blade.

1. Mysql supports sql query, which can realize some related queries and statistics;

2. Redis has relatively high memory requirements. Under limited conditions, all data cannot be placed in redis. ;

3. Mysql prefers to store data, and redis prefers to retrieve data quickly, but redis is not as good as mysql when querying complex table relationships, so you can put popular data in redis, and mysql stores basic data

Related recommendations: redis database tutorial

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