drop table if exists table_02152;

create table table_02152 (a String, b LowCardinality(String)) engine = MergeTree order by a;
insert into table_02152 values ('a_1', 'b_1') ('a_2', 'b_2') ('a_1', 'b_3') ('a_2', 'b_2');

set count_distinct_optimization=true;
select countDistinct(a) from table_02152;
select countDistinct(b) from table_02152;
select uniqExact(m) from (select number, (number / 2)::UInt64 as m from numbers(10));
select uniqExact(x) from numbers(10) group by number % 2 as x;

set count_distinct_optimization=false;
select countDistinct(a) from table_02152;
select countDistinct(b) from table_02152;
select uniqExact(m) from (select number, (number / 2)::UInt64 as m from numbers(10));
select uniqExact(x) from numbers(10) group by number % 2 as x;

drop table if exists table_02152;