true changes

dbms/src/DataStreams/SummingSortedBlockInputStream.cpp

@@ -200,6 +200,10 @@ SummingSortedBlockInputStream::SummingSortedBlockInputStream(
 
 void SummingSortedBlockInputStream::insertCurrentRowIfNeeded(MutableColumns & merged_columns)
 {
+    /// We have nothing to aggregate. It means that it could be non-zero, because we have columns_not_to_aggregate.
+    if (columns_to_aggregate.empty())
+        current_row_is_zero = false;
+
     for (auto & desc : columns_to_aggregate)
     {
         // Do not insert if the aggregation state hasn't been created
@@ -329,11 +333,7 @@ void SummingSortedBlockInputStream::merge(MutableColumns & merged_columns, std::
             current_row_is_zero = true;
         }
         else
-        {
             key_differs = next_key != current_key;
-            /// If current_key is not empty - thats why current_row is not zero.
-            current_row_is_zero = false;
-        }
 
 
         if (key_differs)

dbms/tests/queries/0_stateless/01030_incorrect_count_summing_merge_tree.reference

@@ -3,20 +3,20 @@
 2018-02-02 00:00:00	2
 -- 2 2
 2
-1
+2
 -- 2 2
 2
-1
+2
 -- 2 2
 2
 2
 -- 2 2 2
-1
-1
-1
+2
+2
+2
 -- 2 2
 2
-1
+2
 -- SummingMergeTree with Nullable column with duplicates
 2018-02-01 00:00:00	4
 2018-02-02 00:00:00	6
@@ -50,9 +50,9 @@
 2
 2
 -- 2 2 2
-1
-1
-1
+2
+2
+2
 -- 2 2
 2
 2