**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

.part_backup_path = disk->getPath() + path,
                .backup_name = backup_name,
            });
            LOG_DEBUG(log, "Unfreezed part by path {}", disk->getPath() + path);
        }
    }
    LOG_DEBUG(log, "Unfreezed {} parts", result.size());
    return result;
}
bool MergeTreeData::canReplacePartition(const DataPartPtr & src_part) const
{
    const auto settings = getSettings();
    if (!settings->enable_mixed_granularity_parts || settings->index_granularity_bytes == 0)
    {
        if (!canUseAdaptiveGranularity() && src_part->index_granularity_info.is_adaptive)
            return false;
        if (canUseAdaptiveGranularity() && !src_part->index_granularity_info.is_adaptive)
            return false;
    }
    return true;
}
inline UInt64 time_in_microseconds(std::chrono::time_point<std::chrono::system_clock> timepoint)
{
    return std::chrono::duration_cast<std::chrono::microseconds>(timepoint.time_since_epoch()).count();
}
inline UInt64 time_in_seconds(std::chrono::time_point<std::chrono::system_clock> timepoint)
{
    return std::chrono::duration_cast<std::chrono::seconds>(timepoint.time_since_epoch()).count();
}
void MergeTreeData::writePartLog(