[GENERAL] Altering a table with a rowtype column

[Mike Blackwell]

Given a pair of tables:

create table a (
  id serial,
  stuff text,
  more_stuff text
);

create table a_audit (
  id serial,
  old_record a,
  new_record a
);

How can one alter the structure of table a?  Attempting

ALTER TABLE a ADD COLUMN even_more_stuff text;

results in the message:

 ERROR:  cannot alter table "a" because column "a_audit.new_record" uses
its row type

A solution that doesn't lose the existing data is preferable.

Mike