**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->name = part_name;
    part->info = part_info;
    part->is_temp = false;
    part->setState(DataPartState::PreCommitted);
    part->renameTo(part_name, true);
    auto part_it = data_parts_indexes.insert(part).first;
    if (out_transaction)
    {
        out_transaction->precommitted_parts.insert(part);
    }
    else
    {
        size_t reduce_bytes = 0;
        size_t reduce_rows = 0;
        size_t reduce_parts = 0;
        auto current_time = time(nullptr);
        for (const DataPartPtr & covered_part : covered_parts)
        {
            covered_part->remove_time.store(current_time, std::memory_order_relaxed);
            modifyPartState(covered_part, DataPartState::Outdated);
            removePartContributionToColumnSizes(covered_part);
            reduce_bytes += covered_part->getBytesOnDisk();
            reduce_rows += covered_part->rows_count;
            ++reduce_parts;
        }
        decreaseDataVolume(reduce_bytes, reduce_rows, reduce_parts);
        modifyPartState(part_it, DataPartState::Committed);