Comment by jhancock

Depends on your app cache needs. If it's moderate, I'd start with postgres...ie. not have operate another piece of infra and the extra code. If you are doing the shared-nothing app server approach (rails, django) where the app server remembers nothing after each request Redis can be a handy choice. I often go with having a fat long lived server process (jvm) where it also acts for my live caching needs. #tradeoffs