**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

LOG_WARNING(log, "currently_submerging_big_parts contains duplicates. JBOD might lose balance");
                    else
                        currently_submerging_big_parts.insert(part);
                }
                
                tagger_ptr->emplace(*this, part_name, std::move(covered_parts), log);
            }
        }
    }
    catch (...)
    {
        LOG_DEBUG(log, "JBOD balancer encounters an error. Fallback to random disk selection");
        tryLogCurrentException(log);
    }
    return reserved_space;
}
CurrentlySubmergingEmergingTagger::~CurrentlySubmergingEmergingTagger()
{
    std::lock_guard lock(storage.currently_submerging_emerging_mutex);
    for (const auto & part : submerging_parts)
    {
        if (!storage.currently_submerging_big_parts.count(part))
            LOG_WARNING(log, "currently_submerging_big_parts doesn't contain part {} to erase. This is a bug", part->name);
        else
            storage.currently_submerging_big_parts.erase(part);
    }
    storage.currently_emerging_big_parts.erase(emerging_part_name);
}
}