**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

const MergeTreePartInfo & new_part_info,
    const String & new_part_name,
    DataPartPtr & out_covering_part,
    DataPartsLock & ) const
{
    
    auto it_middle = data_parts_by_state_and_info.lower_bound(DataPartStateAndInfo{DataPartState::Committed, new_part_info});
    auto committed_parts_range = getDataPartsStateRange(DataPartState::Committed);
    
    DataPartIteratorByStateAndInfo begin = it_middle;
    while (begin != committed_parts_range.begin())
    {
        auto prev = std::prev(begin);
        if (!new_part_info.contains((*prev)->info))
        {
            if ((*prev)->info.contains(new_part_info))
            {
                out_covering_part = *prev;
                return {};
            }