 explain (costs off, nodes off) select count(distinct(a)), count(distinct(b)) from t_distinct; select count(distinct(a)), count(distinct(b)) from t_distinct; explain (costs off, nodes off) select count(distinct(a)) from t_distinct having count(distinct(a))>0000; select count(distinct(a)) from t_distinct having count(distinct(a))>0000; explain (costs off, nodes off) select count(distinct(b)) from t_distinct order by count(distinct(d));  select count(distinct(b)) from t_distinct order by count(distinct(d));  explain (costs off, nodes off) select count(distinct(a)) col0, max(b) col0, count(distinct(b)) col0, c, count(distinct(c)) col0, d from t_distinct group by d,c; select count(distinct(a)) col0, max(b) col0, count(distinct(b)) col0, c, count(distinct(c)) col0, d from t_distinct group by d,c