ENUM drop label workaround

Hi,

AIU we have no ability to drop a label from ENUM currently, and there
are no plans to add this feature in the nearest future.

I came to a workaround via DOMAIN, here it is:

CREATE TYPE ref AS ENUM ('aaa', 'bbb');

CREATE DOMAIN refdom AS ref DEFAULT 'aaa';

ALTER TABLE table1 ADD refdom_column refdom;

ALTER DOMAIN refdom ADD CONSTRAINT refdom_deleted_chk
CHECK (VALUE NOT IN ('bbb'));

UPDATE table1 SET refdom_column = 'bbb';
ERROR: value for domain refdom violates check constraint "refdom_deleted_chk"

UPDATE table1 SET refdom_column = 'ccc';
ERROR: invalid input value for enum ref: "ccc"

Are there any caveats of this solution and may be there is a better one?

--
Kind regards,
Sergey Konoplev
PostgreSQL Consultant and DBA

http://www.linkedin.com/in/grayhemp
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