>
>
> PERFORM * FROM ((TABLE old_table EXCEPT TABLE new_table) UNION ALL
> (TABLE new_table EXCEPT TABLE old_table)) AS differences LIMIT 1;
> IF FOUND THEN
> ... changed ...
> END IF;
>
> Maybe converting new and old records to json and text
PERFORM * FROM (select ID, row_to_json(O.*)::text Old_Values,
row_to_json(N.*)::text New_Values from old_table o full outer join
new_table N using(ID) where Old_Values is distinct from New_Values) as
differences LIMIT 1;