Comment by bluGill

What is correct depends on your workload. There is never a case for comparing the performance for Postgres vs Redis. The are intended for very different uses and so they are should never substitute, as a feature analysis will reveal which you really need.

Though to be honest most people won't scale enough that DB performance is important in the first place. For most people they don't even need a database, your language has built in containers that will do everything you need.