Single source of truth and Redux

[gunnarsireus]

Most web applications consist of a database where data is stored and a web interface from which a user can do CRUD operations on the database. This means that data is stored in 2 places. In the database and in the web interface. By using Redux we create a store to be the single source of truth. In reality, the database is the single source of sruth and the web interface is a reflection of the data in the database.
Do your really need Redux when storing data in a database?
Is Redux used on www.facebook.com where ReactJS is used?