   {
     return host_columns[build_column_index]->data;
   }
+
+
 
   __host__ 
   void print_row(const size_type row_index, char * msg = "") const

    device_types.reserve(num_cols);
    for(size_type i = 0; i < num_cols; ++i)
    {
      assert(column_length == host_columns[i]->size);

      device_columns.push_back(host_columns[i]->data);
      device_types.push_back(host_columns[i]->dtype);
    }

    d_columns_data = device_columns.data().get();

  thrust::device_vector<void*> device_columns;
  thrust::device_vector<gdf_dtype> device_types;

  gdf_column ** host_columns{nullptr};
  const size_type num_columns;
  size_type column_length{0};

  size_type row_size_bytes{0};

  // Just use the first column as the build/probe column for now
  const size_type build_column_index{0};
