And waits for them. That's pointless.
part_info.min_block = parts.front()->info.min_block;
    part_info.max_block = parts.back()->info.max_block;
    part_info.level = max_level + 1;
    part_info.mutation = max_mutation;
    if (parts.front()->storage.format_version < MERGE_TREE_DATA_MIN_FORMAT_VERSION_WITH_CUSTOM_PARTITIONING)
    {
        DayNum min_date = DayNum(std::numeric_limits<UInt16>::max());
        DayNum max_date = DayNum(std::numeric_limits<UInt16>::min());
        for (const auto & part : parts)
        {
            
            
            
            
            DayNum part_min_date;
            DayNum part_max_date;
            MergeTreePartInfo::parseMinMaxDatesFromPartName(part->name, part_min_date, part_max_date);
            min_date = std::min(min_date, part_min_date);
            max_date = std::max(max_date, part_max_date);
        }
        name = part_info.getPartNameV0(min_date, max_date);
    }
    else
        name = part_info.getPartName();
}
void FutureMergedMutatedPart::updatePath(const MergeTreeData & storage, const ReservationPtr & reservation)
{
    path = storage.getFullPathOnDisk(reservation->getDisk()) + name + "/";
}
MergeTreeDataMergerMutator::MergeTreeDataMergerMutator(MergeTreeData & data_, size_t background_pool_size_)