Note to anyone reading this blog in the future, this is both very very basic, and also highly misleading. The author makes it seem as though PostGres and Redis are interchangeable and that there's not much difference between them.

This is totally misguided and incorrect.

Redis can be easily deployed such that any request returns in less than a millisecond, and this is where it's most useful. It's also consistent and stable as hell. There are many use-cases for Redis where Postgres is totally unsuitable and doesn't make sense, and vice versa.

Do yourself a favour and ignore this blog (again: inaccurate, poorly benchmarked, misleading) and do your own research and use better sources of information.