**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 :(
#pragma once
#include <Common/ProgressIndication.h>
#include <Common/InterruptListener.h>
#include <Common/ShellCommand.h>
#include <Common/Stopwatch.h>
#include <Core/ExternalTable.h>
#include <Poco/Util/Application.h>
#include <Interpreters/Context.h>
#include <Client/Suggest.h>
#include <Client/QueryFuzzer.h>
#include <boost/program_options.hpp>
namespace po = boost::program_options;
namespace DB
{
namespace ErrorCodes
{
    extern const int NOT_IMPLEMENTED;
}
enum MultiQueryProcessingStage