cleanup and update comments

dbms/src/Interpreters/InterpreterSelectQuery.cpp

@@ -86,10 +86,6 @@
 #include <DataTypes/DataTypeAggregateFunction.h>
 #include <DataStreams/materializeBlock.h>
 
-#include <IO/WriteBufferFromOStream.h>
-
-#include <Processors/printPipeline.h>
-
 
 namespace DB
 {
@@ -2136,7 +2132,7 @@ void InterpreterSelectQuery::executeOrder(QueryPipeline & pipeline, SortingInfoP
             pipeline.addSimpleTransform([&](const Block & header) -> ProcessorPtr
             {
                 return std::make_shared<FinishSortingTransform>(
-                    header, sorting_info->prefix_order_descr, 
+                    header, sorting_info->prefix_order_descr,
                     order_descr, settings.max_block_size, limit);
             });
         }

dbms/src/Processors/Transforms/FinishSortingTransform.cpp

@@ -63,7 +63,7 @@ void FinishSortingTransform::consume(Chunk chunk)
     generated_prefix = false;
 
     // If there were only const columns in sort description, then there is no need to sort.
-    // Return the blocks as is.
+    // Return the chunks as is.
     if (description.empty())
     {
         generated_chunk = std::move(chunk);
@@ -72,7 +72,7 @@ void FinishSortingTransform::consume(Chunk chunk)
 
     removeConstColumns(chunk);
 
-    /// Find the position of last already read key in current block.
+    /// Find the position of last already read key in current chunk.
     if (!chunks.empty())
     {
         size_t size = chunk.getNumRows();
@@ -91,8 +91,8 @@ void FinishSortingTransform::consume(Chunk chunk)
 
         size_t tail_pos = high;
 
-        /// We need to save tail of block, because next block may starts with the same key as in tail
-        /// and we should sort these rows in one chunk.
+        /// We need to save tail of chunk, because next chunk may starts with the same key as in tail
+        /// and we should sort these rows in one portion.
         if (tail_pos != size)
         {
             auto source_columns = chunk.detachColumns();
@@ -112,8 +112,8 @@ void FinishSortingTransform::consume(Chunk chunk)
         }
     }
 
-    /// If we reach here, that means that current block is first in chunk
-    /// or it all consists of rows with the same key as tail of a previous block.
+    /// If we reach here, that means that current cunk is first in portion
+    /// or it all consists of rows with the same key as tail of a previous chunk.
     chunks.push_back(std::move(chunk));
 }
 

dbms/src/Processors/Transforms/FinishSortingTransform.h

@@ -1,8 +1,5 @@
 #pragma once
-
-#include <Core/SortDescription.h>
-#include <Processors/IProcessor.h>
-#include <Processors/Transforms/MergeSortingTransform.h>
+#include <Processors/Transforms/SortingTransform.h>
 
 namespace DB
 {
@@ -28,7 +25,6 @@ private:
     SortDescription description_sorted;
 
     Chunk tail_chunk;
-    // Chunks chunks;
 
     bool end_of_stream = false;
     size_t total_rows_processed = 0;

dbms/src/Processors/Transforms/MergeSortingTransform.cpp

@@ -1,7 +1,6 @@
 #include <Processors/Transforms/MergeSortingTransform.h>
-
-#include <Core/SortDescription.h>
-#include <Core/SortCursor.h>
+#include <Processors/IAccumulatingTransform.h>
+#include <Processors/Transforms/MergingSortedTransform.h>
 
 #include <Common/formatReadable.h>
 #include <Common/ProfileEvents.h>
@@ -12,9 +11,6 @@
 #include <DataStreams/NativeBlockInputStream.h>
 #include <DataStreams/NativeBlockOutputStream.h>
 
-#include <queue>
-#include <Processors/Transforms/MergingSortedTransform.h>
-
 
 namespace ProfileEvents
 {

dbms/src/Processors/Transforms/MergeSortingTransform.h

@@ -40,8 +40,7 @@ private:
     size_t max_bytes_before_external_sort;
     const std::string tmp_path;
 
-    Logger * log = &Logger::get("MergeSortingBlockInputStream");
-    // Chunks chunks;
+    Logger * log = &Logger::get("MergeSortingTransform");
 
     /// If remerge doesn't save memory at least several times, mark it as useless and don't do it anymore.
     bool remerge_is_useful = true;

dbms/src/Processors/Transforms/SortingTransform.cpp

@@ -12,10 +12,6 @@
 #include <DataStreams/NativeBlockInputStream.h>
 #include <DataStreams/NativeBlockOutputStream.h>
 
-#include <queue>
-#include <Processors/ISource.h>
-#include <Processors/Transforms/MergingSortedTransform.h>
-
 
 namespace ProfileEvents
 {

dbms/src/Processors/Transforms/SortingTransform.h

@@ -1,26 +1,12 @@
 #pragma once
-#include <Processors/IAccumulatingTransform.h>
+#include <Processors/IProcessor.h>
 #include <Core/SortDescription.h>
 #include <Core/SortCursor.h>
-#include <Poco/TemporaryFile.h>
 #include <DataStreams/IBlockInputStream.h>
-#include <DataStreams/NativeBlockInputStream.h>
-#include <DataStreams/NativeBlockOutputStream.h>
-
 #include <Processors/ISource.h>
-
-#include <common/logger_useful.h>
-
 #include <queue>
 
 
-namespace ProfileEvents
-{
-    extern const Event ExternalSortWritePart;
-    extern const Event ExternalSortMerge;
-}
-
-
 namespace DB
 {
 
@@ -72,7 +58,9 @@ private:
     MergeSorter merge_sorter;
 };
 
-
+/** Base class for sorting.
+ *  Currently there are two implementations: MergeSortingTransform and FinishSortingTransform.
+ */
 class SortingTransform : public IProcessor
 {
 public:
@@ -91,7 +79,6 @@ protected:
     virtual void generate() = 0;
     virtual void serialize();
 
-protected:
     SortDescription description;
     size_t max_merged_block_size;
     UInt64 limit;