ALTER TABLE media_requests
  ADD COLUMN provider text NOT NULL DEFAULT '',
  ADD COLUMN external_id text NOT NULL DEFAULT '',
  ADD COLUMN original_title text NOT NULL DEFAULT '';

ALTER TABLE media_requests
  ADD CONSTRAINT media_requests_provider_check CHECK (provider IN ('', 'tmdb', 'bangumi')),
  ADD CONSTRAINT media_requests_external_id_length CHECK (length(external_id) <= 512),
  ADD CONSTRAINT media_requests_original_title_length CHECK (length(original_title) <= 300);

CREATE INDEX media_requests_external_metadata_idx
  ON media_requests(provider, external_id)
  WHERE provider <> '' AND external_id <> '';