--
-- util__get_primary_keys/1
--
create or replace function util__get_primary_keys(
  text
) returns name as $$

  SELECT a.attname
    FROM pg_index i
    JOIN pg_attribute a ON a.attrelid = i.indrelid
                       AND a.attnum = ANY(i.indkey)
  WHERE i.indrelid = $1::regclass
    AND i.indisprimary;
$$ language plpgsql;