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DROP SCHEMA IF EXISTS a CASCADE;
CREATE SCHEMA a;

DROP SCHEMA IF EXISTS b CASCADE;
CREATE SCHEMA b;

-- Create the culprit, in a separate schema
CREATE TYPE a.my_enum AS ENUM (
  'option1',
  'option2'
);

CREATE TABLE b.whatever (
  some_int INT,
  something a.my_enum,
  some_text TEXT
) PARTITION BY LIST (something);

CREATE TABLE b.whatever_1 PARTITION OF b.whatever FOR VALUES IN ('option1');
CREATE TABLE b.whatever_2 PARTITION OF b.whatever FOR VALUES IN ('option2');

-- No more schema, no more enum, no more partition key
DROP SCHEMA a CASCADE;

-- Nnope!
DROP SCHEMA b CASCADE;

-- Maybe this?
DROP TABLE b.whatever_1 CASCADE;
DROP TABLE b.whatever_2 CASCADE;
-- it worked. Final touch?
DROP TABLE b.whatever CASCADE;
-- Nope.

-- What's going on?
SELECT * FROM pg_attribute
WHERE
  attrelid IN (SELECT c.oid FROM pg_class c JOIN pg_namespace n ON n.oid = c.relnamespace WHERE c.relname LIKE 'whatever%' AND n.nspname='b')
  AND attnum>0;

--Bad solution
UPDATE pg_attribute
SET atttypid='int'::REGTYPE::INT
WHERE
  attrelid IN (
    SELECT
      c.oid
    FROM pg_class c
    JOIN pg_namespace n
      ON n.oid = c.relnamespace
    WHERE
      c.relname LIKE 'whatever%'
      AND n.nspname='b'
  )
  AND attnum>0
  AND atttypid=0
  AND attlen=4;

-- Works now
DROP SCHEMA b CASCADE;