**Describe the situation**
```
$ ./clickhouse-21.3.3 client --query "SELECT * FROM system.numbers_mt FORMAT Native" | pv > /dev/null
^C,1GiB 0:00:45 [ 710MiB/s] [                                                                                                                                                                                               <=>                      ]

$ ./clickhouse-21.3.3 client --compress 0 --query "SELECT * FROM system.numbers_mt FORMAT Native" | pv > /dev/null
^C,2GiB 0:00:12 [1,48GiB/s] [                                                   <=>                                                                                                                                                                  ]
```

class Pipe;
struct Settings;
struct ExternalTableData
{
    
    std::unique_ptr<Pipe> pipe;
    std::string table_name;
    
    std::atomic_bool is_cancelled = false;
};
using ExternalTableDataPtr = std::unique_ptr<ExternalTableData>;
using ExternalTablesData = std::vector<ExternalTableDataPtr>;
class Connection;