**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

{
    
    
    
    auto volume_ptr = storage_policy->getVolume(storage_policy->getVolumeIndexByDisk(volume->getDisk()));
    return !volume_ptr->areMergesAvoided();
}
UInt64 IMergeTreeDataPart::calculateTotalSizeOnDisk(const DiskPtr & disk_, const String & from)
{
    if (disk_->isFile(from))
        return disk_->getFileSize(from);
    std::vector<std::string> files;
    disk_->listFiles(from, files);
    UInt64 res = 0;
    for (const auto & file : files)
        res += calculateTotalSizeOnDisk(disk_, from + file);
    return res;
}
void IMergeTreeDataPart::renameTo(const String & new_relative_path, bool remove_new_dir_if_exists) const