https://clickhouse-test-reports.s3.yandex.net/17375/99073c26ee2692f8efe2ab14b2d8ae0fd813b80e/fuzzer/fuzzer.log

```
SELECT
    k,
    topK(v)
FROM 
(
    SELECT
        number % 7 AS k,
        arrayMap(x -> arrayMap(x -> if(x = 0, NULL, toString(x)), range(x)), range(intDiv(number, 1))) AS v
    FROM system.numbers
    LIMIT 257
)
GROUP BY k
ORDER BY k ASC
```
LookupResult & it, bool & inserted, size_t hash_value)
    {
        it = &buf[place_value];
        if (!buf[place_value].isZero(*this))
        {
            keyHolderDiscardKey(key_holder);
            inserted = false;
            return;
        }
        keyHolderPersistKey(key_holder);