Postgres trigger есть ли поле в запросе

CREATE OR REPLACE FUNCTION completed_upsert_v1() RETURNS TRIGGER AS
$BODY$
BEGIN
    IF (NEW.is_completed IS NOT NULL) THEN
        NEW.completed = NEW.is_completed;
    END IF;

    RETURN NEW;
END ;
$BODY$ LANGUAGE plpgsql;

CREATE TRIGGER completed_trigger
    BEFORE INSERT OR UPDATE ON some_table
    FOR EACH ROW
EXECUTE PROCEDURE completed_upsert_v1();

есть ли возможность понять разницу между

update some_table set is_completed = null where id = 10

или

update some_table set another_field = 'some value' where id = 10

т.е. NEW.is_completed в обоих случаях будет NULL