How to change the order of an existing postgres enum

Question

I have a postgres enum that would like to change its default sort order

I learned about the pg_enum type enumsortorder but haven't found any documentation on how to change the order.

The enum I have for context:

CREATE TYPE day AS ENUM (
            'everyday', 
            'sunday',
            'monday',
            'tuesday',
            'wednesday',
            'thursday',
            'friday',
            'saturday'
          );

Currently when I retrieve ordered by day I get from 'everyday' to 'saturday'. I would like to get from Monday-Sunday and have Everyday as the last value.

Is this possible?

Answer 1

You can only replace the type with a new one, which can be a bit laborious. Eg:

BEGIN;

-- drop views, functions which are using day

ALTER TYPE day RENAME TO day_old;
CREATE TYPE day AS ENUM (
        'everyday', 
        'monday',
        'tuesday',
        'wednesday',
        'thursday',
        'friday',
        'saturday',
        'sunday'
);

ALTER TABLE x ALTER my_day TYPE day USING my_day::TEXT::day;
ALTER TABLE y ALTER your_day TYPE day USING your_day::TEXT::day;
-- etc. etc.
-- Recreate views, functions which are using day
DROP TYPE day_old;

END;

Answer 2

That's not possible.

Quote from the manual

Existing values cannot be removed from an enum type, nor can the sort ordering of such values be changed , short of dropping and re-creating the enum type

^{(Emphasis mine)}