**Describe the bug**

I have a table like:

```
CREATE TABLE test (
    time DateTime64(3)
    ...
) ENGINE = MergeTree()
PARTITION BY toStartOfInterval(time, INTERVAL 1 HOUR)
...
```

But when I search in `system.parts` it does not appear to have the `min/max` columns appropriately set?

```
partition:                             2020-06-01 01:00:00
min_date:                              1970-01-01
max_date:                              1970-01-01
min_time:                              1970-01-01 00:00:00
max_time:                              1970-01-01 00:00:00
```

I assume that if these were correctly set, doing a `select toStartOfInterval(time, interval 1 day), count()` type query would be pretty instant rather than trying to scan everything? I am guessing this is due to the `DateTime64` type in use?

Clickhouse 20.11.3.3

}
        }
        if (!candidates.empty())
        {
            
            std::shuffle(candidates.begin(), candidates.end(), thread_local_rng);
            String selected_disk_name = candidates.front();
            WriteBufferFromOwnString log_str;
            writeCString("\nbalancer: \n", log_str);
            for (const auto & [disk_name, per_disk_parts] : disk_parts_for_logging)
                writeString(fmt::format("  {}: [{}]\n", disk_name, fmt::join(per_disk_parts, ", ")), log_str);
            LOG_DEBUG(log, log_str.str());
            if (ttl_infos)
                reserved_space = tryReserveSpacePreferringTTLRules(
                    metadata_snapshot,
                    part_size,
                    *ttl_infos,
                    time(nullptr),
                    max_volume_index,
                    is_insert,
                    getStoragePolicy()->getDiskByName(selected_disk_name));
            else
                reserved_space = tryReserveSpace(part_size, getStoragePolicy()->getDiskByName(selected_disk_name));
            if (reserved_space)
            {
                currently_emerging_big_parts.emplace(
                    part_name, EmergingPartInfo{reserved_space->getDisk(0)->getName(), part_info.partition_id, part_size});
                for (const auto & part : covered_parts)
                {
                    if (currently_submerging_big_parts.count(part))