From the docs (as I suspect you already know): ALTER TYPE ... ADD VALUE (the form that adds a new value to an enum type) cannot be executed inside a transaction

From the docs (as I suspect you already know): ALTER TYPE ... ADD VALUE (the form that adds a new value to an enum type) cannot be executed inside a transaction block Also, removing a value is a pain (though, that may have changed now). I know you can do it — but I've found after trying a bunch of approaches that text with constraints is a better starting point. Just wanted to point it out because it's something I researched a fair amount. Many guides say that enum can be a pain but I decided that I'd use them to be pure, then discovered they were a pain, and now don't use them as a starting point.