`Selected 13 parts by date, 13 parts by key, 26 marks by primary key .... `

This message is confusing for new users.

I suggest to replace it with

`Selected 13 parts by partition key, 13 parts by primary key, 26 marks by primary key...`
});
    Names sort_columns = metadata_snapshot->getSortingKeyColumns();
    SortDescription sort_description;
    size_t sort_columns_size = sort_columns.size();
    sort_description.reserve(sort_columns_size);
    Names partition_key_columns = metadata_snapshot->getPartitionKey().column_names;
    Block header = pipe.getHeader();
    for (size_t i = 0; i < sort_columns_size; ++i)
        sort_description.emplace_back(header.getPositionByName(sort_columns[i]), 1, 1);
    auto get_merging_processor = [&]() -> MergingTransformPtr
    {
        switch (data.merging_params.mode)
        {
            case MergeTreeData::MergingParams::Ordinary:
            {
                return std::make_shared<MergingSortedTransform>(header, pipe.numOutputPorts(),
                           sort_description, max_block_size);
            }
            case MergeTreeData::MergingParams::Collapsing:
                return std::make_shared<CollapsingSortedTransform>(header, pipe.numOutputPorts(),
                           sort_description, data.merging_params.sign_column, true, max_block_size);
            case MergeTreeData::MergingParams::Summing:
                return std::make_shared<SummingSortedTransform>(header, pipe.numOutputPorts(),
                           sort_description, data.merging_params.columns_to_sum, partition_key_columns, max_block_size);
            case MergeTreeData::MergingParams::Aggregating:
                return std::make_shared<AggregatingSortedTransform>(header, pipe.numOutputPorts(),
                           sort_description, max_block_size);
            case MergeTreeData::MergingParams::Replacing:
                return std::make_shared<ReplacingSortedTransform>(header, pipe.numOutputPorts(),
                           sort_description, data.merging_params.version_column, max_block_size);