Why is Redis recommended for Spring Session?

Question

Java

I have a Spring MVC application with a PostgreSQL database. I want to connect Spring Session in order to make my application stateless. Very many sources mention REDIS as a database for storing sessions. However, here I also found a JDBC connection option. In this case, as far as I understand, my database (PostgreSQL in my case) will be used to store sessions .

Several questions arose:

1. Why is Redis so popular for session storage? Why is it better than MySQL or PostgreSQL?
   
2. If I want to simultaneously save my objects in PostgreSQL, and sessions in Redis, then Spring will not swear at this? Will I need additional settings, like the one described here ?
   

Answer 1

Redis is more popular for this sort of thing - it's faster than MySQL or PostgreSQL.
The range of problems that can be solved using radish is quite small, but almost always it will be a quick and easy solution.

Answer 2

How can Redis compare to MySQL or PostgreSQL? They are completely different products with different purposes.
Not only is Redis a key-value database, while MySQL and PostgreSQL are RDBMS, but Redis is an in-memory database. That is, they are completely different things used for different purposes.