21.7.3 throws an exception if `_sample_factor` is used in a query:
```
CREATE TABLE sessions
(
  `user_id` UInt64
)
ENGINE = MergeTree
ORDER BY user_id 
SAMPLE BY user_id;

insert into sessions values(1);

SELECT
    sum(user_id * _sample_factor) 
FROM sessions
SAMPLE 10000000

DB::Exception: Cannot find column `user_id` in source stream (version 21.8.1.7409 (official build))

SELECT
    sum(user_id) 
FROM sessions
SAMPLE 10000000

sum(user_id)
------------
           1
```
No exception on 21.6.5
{
        Processors transforms;
        std::vector<OutputPorts::iterator> output_ports;
        transforms.reserve(ports.size() + num_output_streams);
        output_ports.reserve(ports.size());
        for (auto & port : ports)
        {
            auto copier = std::make_shared<CopyTransform>(header, num_output_streams);
            connect(*port, copier->getInputPort());
            output_ports.emplace_back(copier->getOutputs().begin());
            transforms.emplace_back(std::move(copier));
        }
        for (size_t i = 0; i < num_output_streams; ++i)
        {
            auto merge = get_merging_processor();
            merge->setSelectorPosition(i);
            auto input = merge->getInputs().begin();
            
            for (size_t j = 0; j < ports.size(); ++j)
            {
                connect(*output_ports[j], *input);
                ++output_ports[j];
                ++input;
            }
            transforms.emplace_back(std::move(merge));
        }
        return transforms;
    });
}
Pipe ReadFromMergeTree::spreadMarkRangesAmongStreamsFinal(