ClickHouse: Wrong query result because of push-down optimization

21.8.4.51 / 21.9.2.17

select cnt from (select count() cnt where 0) where cnt = 0;
0 rows in set. Elapsed: 0.002 sec.


select cnt from (select count() cnt from system.one where 0) where cnt = 0;
0 rows in set. Elapsed: 0.001 sec.


select sum from (select sum(dummy) sum from system.one where 0) where sum = 0;
0 rows in set. Elapsed: 0.001 sec.


set aggregate_functions_null_for_empty=1;
select sum from (select sum(dummy) sum from system.one where 0)where sum is null　;
0 rows in set. Elapsed: 0.002 sec.

-- workaround to prevent pushdown
select cnt from (select count() cnt where 0 limit 1000000000) where cnt = 0;
┌─cnt─┐
│   0 │
└─────┘

20.8.18.32 / 21.3.16.5 / 21.5.9 / 21.7.9.7 -- correct result

select cnt from (select count() cnt where 0) where cnt = 0;
┌─cnt─┐
│   0 │
└─────┘

select cnt from (select count() cnt from system.one where 0) where cnt = 0;
┌─cnt─┐
│   0 │
└─────┘

select sum from (select sum(dummy) sum from system.one where 0) where sum = 0;
┌─sum─┐
│   0 │
└─────┘

set aggregate_functions_null_for_empty=1;
select sum from (select sum(dummy) sum from system.one where 0)where sum is null　;
┌──sum─┐
│ ᴺᵁᴸᴸ │
└──────┘