Do not forget to check for NULL [NULL + int in postgres results in NULL]

-- Function: update_total_votes_pictures()

-- DROP FUNCTION update_total_votes_pictures();

CREATE OR REPLACE FUNCTION update_total_votes_pictures()
RETURNS int4 AS
$BODY$ -- returns the number of pixpair entries that were created
DECLARE
_count integer;
all RECORD;
_total_a integer;
_total_b integer;
_total integer;
BEGIN

_count := 0;

FOR all in
select id from pictures
LOOP
select into _total_a sum(pic1_votes) from pixpair where pic1_id = all.id;
if ( _total_a is NULL ) then
_total_a := 0;
end if;
select into _total_b sum(pic2_votes) from pixpair where pic2_id = all.id;
if ( _total_b is NULL ) then
_total_b := 0;
end if;
_total := _total_a + _total_b;
update pictures set total_votes = _total where id = all.id;

_count := _count + 1;
END LOOP;

return _count;
END;
$BODY$
LANGUAGE 'plpgsql' VOLATILE;
ALTER FUNCTION update_total_votes_pictures() OWNER TO postgres;