better

src/Processors/Formats/IRowInputFormat.h

@@ -53,7 +53,6 @@ public:
     void resetParser() override;
 
 protected:
-    friend class ParallelParsingInputFormat;
     /** Read next row and append it to the columns.
       * If no more rows - return false.
       */

src/Processors/Formats/Impl/CSVRowInputFormat.cpp

@@ -8,8 +8,6 @@
 #include <DataTypes/DataTypeNothing.h>
 
 
-#include <iostream>
-
 namespace DB
 {
 
@@ -157,6 +155,8 @@ void CSVRowInputFormat::readPrefix()
     size_t num_columns = data_types.size();
     const auto & header = getPort().getHeader();
 
+    /// This is a bit of abstraction leakage, but we have almost the same code in other places.
+    /// Thus, we check if this InputFormat is working with the "real" beggining of the data in case of parallel parsing.
     if (with_names && getCurrentUnitNumber() == 0)
     {
         /// This CSV file has a header row with column names. Depending on the

src/Processors/Formats/Impl/TabSeparatedRowInputFormat.cpp

@@ -136,6 +136,8 @@ void TabSeparatedRowInputFormat::readPrefix()
         skipBOMIfExists(in);
     }
 
+    /// This is a bit of abstraction leakage, but we have almost the same code in other places.
+    /// Thus, we check if this InputFormat is working with the "real" beggining of the data in case of parallel parsing.
     if (with_names && getCurrentUnitNumber() == 0)
     {
         if (format_settings.with_names_use_header)