Redis is great, it's a great piece of software. One way I shot myself in the foot (kinda) with it: used it with a 1:N query fanout pattern. I.e., issued N queries to Redis for 1 incoming query to my service. My service by design needs to do N queries (it's a long story). But Redis is not really designed to be used like this and I was putting it under very high load. I swapped it out with an SQLite cache recently and got rid of the errors that would pop up from putting extreme stress on the Redis server.