**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

{
    assertOnDisk();
    String from = getFullRelativePath();
    String to = storage.relative_data_path + new_relative_path + "/";
    if (!volume->getDisk()->exists(from))
        throw Exception("Part directory " + fullPath(volume->getDisk(), from) + " doesn't exist. Most likely it is a logical error.", ErrorCodes::FILE_DOESNT_EXIST);
    if (volume->getDisk()->exists(to))
    {
        if (remove_new_dir_if_exists)
        {
            Names files;
            volume->getDisk()->listFiles(to, files);
            LOG_WARNING(storage.log, "Part directory {} already exists and contains {} files. Removing it.", fullPath(volume->getDisk(), to), files.size());
            volume->getDisk()->removeRecursive(to);
        }
        else
        {
            throw Exception("Part directory " + fullPath(volume->getDisk(), to) + " already exists", ErrorCodes::DIRECTORY_ALREADY_EXISTS);
        }
    }
    volume->getDisk()->setLastModified(from, Poco::Timestamp::fromEpochTime(time(nullptr)));
    volume->getDisk()->moveDirectory(from, to);
    relative_path = new_relative_path;
    SyncGuardPtr sync_guard;
    if (storage.getSettings()->fsync_part_directory)
        sync_guard = volume->getDisk()->getDirectorySyncGuard(to);
    storage.lockSharedData(*this);
}
void IMergeTreeDataPart::remove(bool keep_s3) const