**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 (!isEmpty())
    {
        WriteBufferFromOwnString buf;
        buf << " Removing parts:";
        for (const auto & part : precommitted_parts)
            buf << " " << part->relative_path;
        buf << ".";
        LOG_DEBUG(data.log, "Undoing transaction.{}", buf.str());
        data.removePartsFromWorkingSet(
            DataPartsVector(precommitted_parts.begin(), precommitted_parts.end()),
             true);
    }
    clear();
}
MergeTreeData::DataPartsVector MergeTreeData::Transaction::commit(MergeTreeData::DataPartsLock * acquired_parts_lock)