**Describe the situation**

```
SELECT * FROM test.hits INTO OUTFILE 'dump.csv' FORMAT CSV

8873898 rows in set. Elapsed: 32.487 sec. Processed 8.87 million rows, 8.46 GB (273.15 thousand rows/s., 260.42 MB/s.)
```

is bounded by single CPU core. Too slow :(
/// param_name value
                    ++a
                    if (arg_num >= argc)
                        throw Exception("Parameter requires value", ErrorCodes::BAD_ARGUMENTS
                    arg = argv[arg_num];
                    quee(String(param_continuation), String(arg)
                }
            }
            else
                common_arguments.emplace_back(arg
        }
    }
}
void ClientBase::parseAndCheckOptions(OptionsDescription & options_description, po::variables_map & options, Arguments & arguments)
{
    cmd_settings.addProgramOptions(options_description.main_description.value()
    /// Parse main commandline options.
    auto rguments).options(options_description.main_description.value()).allow_unregistered(
    po::parsed_options parsed = parser.run(
    /// Check unrecognized options without positional options.
    auto unrecognized_options = po::collect_unrecognized(parsed.options, po::collect_unrecognized_mode::exclude_positional
    if (!unrecognized_options.empty())
        throw Exception(ErrorCodes::UNRECOGNIZED_ARGUMENTS, "Unrecognized option '{}'", unrecognized_options[0]
    /// Check positional options (options after ' -- ', ex: clickhouse-client -- <options>).
    unrecognized_options = po::collect_unrecognized(parsed.options, po::collect_unrecognized_mode::include_positional
    if (unrecognized_options.size() > 1)
        throw Exception(ErrorCodes::BAD_ARGUMENTS, "Positional options are not supported."
    po::store(parsed, options
}
void ClientBase::init(int argc, char ** argv)