**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 (MergeTreePartInfo::tryParsePartName(part_id, nullptr, format_version))
            name_to_disk[part_id] = getDiskForPart(part_id, source_dir);
    }
    else
    {
        String partition_id = getPartitionIDFromQuery(partition, context);
        LOG_DEBUG(log, "Looking for parts for partition {} in {}", partition_id, source_dir);
        ActiveDataPartSet active_parts(format_version);
        const auto disks = getStoragePolicy()->getDisks();
        for (const auto & disk : disks)
        {
            for (auto it = disk->iterateDirectory(relative_data_path + source_dir); it->isValid(); it->next())
            {
                const String & name = it->name();
                MergeTreePartInfo part_info;
                
                
                if (!MergeTreePartInfo::tryParsePartName(name, &part_info, format_version)
                    || part_info.partition_id != partition_id)
                {
                    continue;
                }
                LOG_DEBUG(log, "Found part {}", name);
                active_parts.add(name);
                name_to_disk[name] = disk;
            }
        }
        LOG_DEBUG(log, "{} of them are active", active_parts.size());
        
        for (const auto & [name, disk] : name_to_disk)