**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 (out_transaction && &out_transaction->data != this)
        throw Exception("MergeTreeData::Transaction for one table cannot be used with another. It is a bug.",
            ErrorCodes::LOGICAL_ERROR);
    DataPartsVector covered_parts;
    {
        auto lock = lockParts();
        if (!renameTempPartAndReplace(part, increment, out_transaction, lock, &covered_parts))
            return false;
    }
    if (!covered_parts.empty())
        throw Exception("Added part " + part->name + " covers " + toString(covered_parts.size())
            + " existing part(s) (including " + covered_parts[0]->name + ")", ErrorCodes::LOGICAL_ERROR);
    return true;
}
bool MergeTreeData::renameTempPartAndReplace(