-- A disabled row records binding history only. It must not reserve the numeric
-- Telegram identity forever, otherwise a user who unbinds cannot bind a newly
-- registered panel account.
ALTER TABLE telegram_accounts DROP CONSTRAINT IF EXISTS telegram_accounts_telegram_user_id_key;
CREATE UNIQUE INDEX IF NOT EXISTS telegram_accounts_telegram_user_id_active_idx
  ON telegram_accounts(telegram_user_id)
  WHERE disabled_at IS NULL;