From 48505446af4947f1f146d649b122bfbf63d6fe3d Mon Sep 17 00:00:00 2001
From: Alexey Milovidov <milovidov@yandex-team.ru>
Date: Sun, 22 Dec 2019 04:49:38 +0300
Subject: [PATCH] Addition to prev. revision

---
 .../DataStreams/MergeSortingBlockInputStream.cpp  | 15 ++++++++++-----
 .../DataStreams/MergeSortingBlockInputStream.h    |  1 +
 .../DataStreams/MergingSortedBlockInputStream.cpp |  6 +++---
 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/dbms/src/DataStreams/MergeSortingBlockInputStream.cpp b/dbms/src/DataStreams/MergeSortingBlockInputStream.cpp
index 8664b62bf75..52f85f1349c 100644
--- a/dbms/src/DataStreams/MergeSortingBlockInputStream.cpp
+++ b/dbms/src/DataStreams/MergeSortingBlockInputStream.cpp
@@ -150,10 +150,12 @@ MergeSortingBlocksBlockInputStream::MergeSortingBlocksBlockInputStream(
 
     blocks.swap(nonempty_blocks);
 
-    if (!has_collation)
+    if (has_collation)
+        queue_with_collation = SortingHeap<SortCursorWithCollation>(cursors);
+    else if (description.size() > 1)
         queue_without_collation = SortingHeap<SortCursor>(cursors);
     else
-        queue_with_collation = SortingHeap<SortCursorWithCollation>(cursors);
+        queue_simple = SortingHeap<SimpleSortCursor>(cursors);
 }
 
 
@@ -169,9 +171,12 @@ Block MergeSortingBlocksBlockInputStream::readImpl()
         return res;
     }
 
-    return !has_collation
-        ? mergeImpl(queue_without_collation)
-        : mergeImpl(queue_with_collation);
+    if (has_collation)
+        return mergeImpl(queue_with_collation);
+    else if (description.size() > 1)
+        return mergeImpl(queue_without_collation);
+    else
+        return mergeImpl(queue_simple);
 }
 
 
diff --git a/dbms/src/DataStreams/MergeSortingBlockInputStream.h b/dbms/src/DataStreams/MergeSortingBlockInputStream.h
index 9492bdb074b..ce82f6bb120 100644
--- a/dbms/src/DataStreams/MergeSortingBlockInputStream.h
+++ b/dbms/src/DataStreams/MergeSortingBlockInputStream.h
@@ -59,6 +59,7 @@ private:
     bool has_collation = false;
 
     SortingHeap<SortCursor> queue_without_collation;
+    SortingHeap<SimpleSortCursor> queue_simple;
     SortingHeap<SortCursorWithCollation> queue_with_collation;
 
     /** Two different cursors are supported - with and without Collation.
diff --git a/dbms/src/DataStreams/MergingSortedBlockInputStream.cpp b/dbms/src/DataStreams/MergingSortedBlockInputStream.cpp
index 57742fe1e35..7f6bf6a0d90 100644
--- a/dbms/src/DataStreams/MergingSortedBlockInputStream.cpp
+++ b/dbms/src/DataStreams/MergingSortedBlockInputStream.cpp
@@ -58,10 +58,10 @@ void MergingSortedBlockInputStream::init(MutableColumns & merged_columns)
             has_collation |= cursors[i].has_collation;
         }
 
-        if (!has_collation)
-            queue_without_collation = SortingHeap<SortCursor>(cursors);
-        else if (description.size() > 1)
+        if (has_collation)
             queue_with_collation = SortingHeap<SortCursorWithCollation>(cursors);
+        else if (description.size() > 1)
+            queue_without_collation = SortingHeap<SortCursor>(cursors);
         else
             queue_simple = SortingHeap<SimpleSortCursor>(cursors);
     }