**Use case**
Clickhouse version 21.4
```
SELECT
    quantileTiming(0.95)(key) AS timing,
    quantileExact(0.95)(key) AS exact,
    quantileTDigest(0.95)(key) AS tdigest
FROM
(
    SELECT
        9000 AS key,
        2 AS count
    UNION ALL
    SELECT
        3000,
        11
    UNION ALL
    SELECT
        1000,
        26
)
ARRAY JOIN range(count) AS s

Query id: addce63f-0b75-46e2-b896-712d66711fb0

┌─timing─┬─exact─┬──tdigest─┐
│   9000 │  9000 │ 8123.076 │
└────────┴───────┴──────────┘


SELECT
    quantileTiming(0.9)(key) AS timing,
    quantileExact(0.9)(key) AS exact,
    quantileTDigest(0.9)(key) AS tdigest
FROM
(
    SELECT key
    FROM
    (
        SELECT
            9000 AS key,
            2 AS count
        UNION ALL
        SELECT
            3000,
            11
        UNION ALL
        SELECT
            1000,
            26
    )
    ARRAY JOIN range(count) AS s
    ORDER BY key ASC
)

Query id: e92e3d07-3b97-4155-aa10-9a15544d9312

┌─timing─┬─exact─┬───tdigest─┐
│   3000 │  3000 │ 6323.0757 │
└────────┴───────┴───────────┘

```

Probably related: https://github.com/tdunning/t-digest/issues/154
return;
                x = levels[levels_permutation[result_num]] * count;
            }
            sum += c.count;
            prev_mean = c.mean;
            prev_x = current_x;
        }
        auto rest_of_results = centroids.back().mean;
        for (; result_num < size; ++result_num)
            result[levels_permutation[result_num]] = rest_of_results;
    }
    T get(Float64 level)
    {
        return getImpl<T>(level);
    }
    Float32 getFloat(Float64 level)
    {
        return getImpl<Float32>(level);
    }
    void getMany(const Float64 * levels, const size_t * indices, size_t size, T * result)
    {
        getManyImpl(levels, indices, size, result);
    }
    void getManyFloat(const Float64 * levels, const size_t * indices, size_t size, Float32 * result)
    {
        getManyImpl(levels, indices, size, result);
    }
};
}