Many friends are confused whether to learn redis or mysql when learning databases. Today I will tell you about the difference and difficulty between the two.
1. Summary of the differences between redis and mysql
Type wise
In terms of type, mysql is a relational database and redis is a cache database
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
Requirements
Mysql and redis are generally used together due to different needs. (redis tutorial)
2. Detailed description
1. Mysql and redis database types
mysql It is a relational database, mainly used to store persistent data. It stores data on the hard disk and has slow reading speed.
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. Mysql operating mechanism
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 advantage of caching is that the reading speed is fast
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.
3. Difficulty level
It can be said that redis is simpler than mysql, but due to project needs, the two are often used in combination. If you learn one database well, others will be easy to understand.
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