**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

columns[res_index++]->insert(part->info.partition_id);
            if (columns_mask[src_index++])
                columns[res_index++]->insert(part->info.min_block);
            if (columns_mask[src_index++])
                columns[res_index++]->insert(part->info.max_block);
            if (columns_mask[src_index++])
                columns[res_index++]->insert(part->info.level);
            if (columns_mask[src_index++])
                columns[res_index++]->insert(UInt64(part->info.getDataVersion()));
            if (columns_mask[src_index++])
                columns[res_index++]->insert(index_size_in_bytes);
            if (columns_mask[src_index++])
                columns[res_index++]->insert(index_size_in_allocated_bytes);
            if (columns_mask[src_index++])
                columns[res_index++]->insert(info.database);
            if (columns_mask[src_index++])
                columns[res_index++]->insert(info.table);
            if (columns_mask[src_index++])
                columns[res_index++]->insert(info.engine);
            if (columns_mask[src_index++])
                columns[res_index++]->insert(part->volume->getDisk()->getName());
            if (columns_mask[src_index++])
                columns[res_index++]->insert(part->getFullPath());
            if (columns_mask[src_index++])
                columns[res_index++]->insert(column.name);
            if (columns_mask[src_index++])
                columns[res_index++]->insert(column.type->getName());
            if (columns_mask[src_index++])
                columns[res_index++]->insert(column_position);
            auto column_info_it = columns_info.find(column.name);