Perhaps I was unclear, my underlying point is that short strings are cheap. And enum names are almost always short strings. 4 characters not enough? What about 8? That’s the size of a BIGINT, which everybody now uses for primary keys (they’re not slow). What about 16 characters? That’s the size of a UUID, which everyone now uses for primary keys (they’re not slow).
Even 4 characters (which perform just as fast as Postgres’ native enums) is enough if you develop a system of abbreviations. The airline industry gets by with just three characters!
Just wanted to let you know I really appreciate your comments. I hadn't thought about doing it the way you recommend (in my mind I was thinking "oh, storing enum values as text will be inefficient", but I never did the math as you did to realize storing anything up to 8 chars is no worse than bigint), but I think it's a pretty optimal solution. I also checked my DB where we heavily use enums, and basically every enum text value that is longer than 8 characters could easily be shortened/abbreviated to 8 chars and still be very easily understood. Thanks very much!
Even 4 characters (which perform just as fast as Postgres’ native enums) is enough if you develop a system of abbreviations. The airline industry gets by with just three characters!