Listing all parts in log have no sense. 
Should be either silenced, either combined into a single line.
}
        else
        {
            
            
            for (auto it = ranges.rbegin(); it != ranges.rend(); ++it)
            {
                auto range = *it;
                while (range.begin + marks_in_range < range.end)
                {
                    new_ranges.emplace_front(range.end - marks_in_range, range.end);
                    range.end -= marks_in_range;
                    marks_in_range = std::min(marks_in_range * 2, max_marks_in_range);
                }
                new_ranges.emplace_front(range.begin, range.end);
            }
        }
        return new_ranges;
    };
    const size_t min_marks_per_stream = (sum_marks - 1) / num_streams + 1;
    bool need_preliminary_merge = (parts.size() > settings.read_in_order_two_level_merge_threshold);
    std::vector<QueryPlanPtr> plans;
    for (size_t i = 0; i < num_streams && !parts.empty(); ++i)
    {
        size_t need_marks = min_marks_per_stream;
        Pipes pipes;
        
        
        
        while (need_marks > 0 && !parts.empty())