I think you can get what you want if you change the rule definition to
CREATE RULE
people_upd_history AS ON UPDATE TO people
DO INSERT INTO
people_history
SELECT * FROM only people WHERE usr_pkey = old.usr_pkey;
and your updates to be only's
-- update table (1) -- 2
UPDATE ONLY people SET color = 'cyan' WHERE usr_pkey = 1;
-- update table (2) -- 6
UPDATE ONLY people SET color = 'magenta' WHERE usr_pkey = 1;
-- update table (3) -- 42
UPDATE ONLY people SET color = 'yellow' WHERE usr_pkey = 1;
-- update table (4) -- 1806
UPDATE ONLY people SET color = 'black' WHERE usr_pkey = 1;
klint.
+---------------------------------------+-----------------+
: Klint Gore : "Non rhyming :
: EMail : kg@kgb.une.edu.au : slang - the :
: Snail : A.B.R.I. : possibilities :
: Mail University of New England : are useless" :
: Armidale NSW 2351 Australia : L.J.J. :
: Fax : +61 2 6772 5376 : :
+---------------------------------------+-----------------+