create table
    t (
        ts timestamp time index,
        `id` int,
        `name` string,
        PRIMARY KEY (`id`),
    );

Affected Rows: 0

insert into
    t (ts, `id`, `name`)
values
    (1, 1, 'a'),
    (2, 2, 'b'),
    (3, 3, 'c'),
    (4, 4, 'd');

Affected Rows: 4

select
    count_hash (`id`)
from
    t;

+------------------+
| count_hash(t.id) |
+------------------+
| 4                |
+------------------+

select
    count_hash (`id`)
from
    t
group by
    `name`;

+------------------+
| count_hash(t.id) |
+------------------+
| 1                |
| 1                |
| 1                |
| 1                |
+------------------+

select
    count_hash (`id`, `name`)
from
    t
group by
    ts;

Error: 3001(EngineExecuteQuery), This feature is not implemented: count_hash with multiple arguments

drop table t;

Affected Rows: 0