CREATE OR REPLACE FUNCTION public.set_relay_id ()
  RETURNS TRIGGER
  LANGUAGE plpgsql
  AS $$
DECLARE
  _new record;
  _json_string text;
BEGIN
  _new := NEW;
  -- assuming the pk column is named "pk" and the table has an "id" text column
  -- same as [1, "public", "table_name", "pk"]
  _json_string = concat(
    '[1, "', TG_TABLE_SCHEMA, '", "', TG_TABLE_NAME, '", ', _new.pk, ']');
  _new."id" = encode(_json_string::bytea, 'base64');
  RETURN _new;
END;
$$;

CREATE TRIGGER "set_authors_relay_id"
BEFORE INSERT ON public.authors
FOR EACH ROW
EXECUTE FUNCTION public.set_relay_id ();

COMMENT ON TRIGGER "set_authors_relay_id" ON public.authors IS
  'trigger to set value of column "id" after insert';