That's called sharding and is pretty widely used nowadays. There is even readily available middleware that handles this for you, so no need to put it into the backend.
Break middle-school students' copypasta CSS rules for animated GIF backgrounds at your peril.
https://www.joelonsoftware.com/2000/04/06/things-you-should-...
I remember him telling me how I was wasting my time building in php/MySQL since CF was the future and serious companies wouldn't be looking for php developers. Glad I never pulled the trigger and bought their expensive IDE.