**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

{
            String containing_part = active_parts.getContainingPart(name);
            if (!containing_part.empty() && containing_part != name)
            {
                
                disk->moveDirectory(relative_data_path + source_dir + name, relative_data_path + source_dir + "inactive_" + name);
            }
            else
                renamed_parts.addPart(name, "attaching_" + name);
        }
    }
    
    renamed_parts.tryRenameAll();
    
    LOG_DEBUG(log, "Checking parts");
    MutableDataPartsVector loaded_parts;
    loaded_parts.reserve(renamed_parts.old_and_new_names.size());
    for (const auto & part_names : renamed_parts.old_and_new_names)
    {
        LOG_DEBUG(log, "Checking part {}", part_names.second);
        auto single_disk_volume = std::make_shared<SingleDiskVolume>("volume_" + part_names.first, name_to_disk[part_names.first], 0);
        MutableDataPartPtr part = createPart(part_names.first, single_disk_volume, source_dir + part_names.second);
        loadPartAndFixMetadataImpl(part);
        loaded_parts.push_back(part);
    }
    return loaded_parts;
}
namespace
{
inline ReservationPtr checkAndReturnReservation(UInt64 expected_size, ReservationPtr reservation)