> Why, exactly, do we need to put a memory cache such as Redis in front of Postgres? Maybe you don't want to run the same expensive queries all the time to ser

> Why, exactly, do we need to put a memory cache such as Redis in front of Postgres? Maybe you don't want to run the same expensive queries all the time to serve your json API? There's a million reasons you might want to cache expensive queries somewhere upstream from the actual database.