Added a class Frame_unbounded_following_set_count_special, which is required to ignore

all the null values while calculating the number of rows in the partition

sql/sql_window.cc

@@ -908,13 +908,14 @@ class Table_read_cursor : public Rowid_seq_cursor
 class Partition_read_cursor : public Table_read_cursor
 {
 public:
-  Partition_read_cursor(THD *thd, SQL_I_List<ORDER> *partition_list) :
-    bound_tracker(thd, partition_list) {}
+  Partition_read_cursor(THD *thd, SQL_I_List<ORDER> *partition_list, SQL_I_List<ORDER> *order_list) :
+    bound_tracker(thd, partition_list), order_tracker(thd, order_list) {}
 
   void init(READ_RECORD *info)
   {
     Table_read_cursor::init(info);
     bound_tracker.init();
+    order_tracker.init();
     end_of_partition= false;
   }
 
@@ -966,9 +967,39 @@ class Partition_read_cursor : public Table_read_cursor
     }
     return 0;
   }
+  bool next_func(ha_rows *counter)
+  {
+    if (next())
+      return true;
+    if (!check_for_null_row())
+    {
+      (*counter)++;
+    }
+    return false;
+  }
+  bool fetch_func(ha_rows *counter)
+  {
+    if (fetch())
+      return true;
+    if (!check_for_null_row())
+    {
+      (*counter)++;
+    }
+    return false;
+  }
+  bool check_for_null_row()
+  {
+    if (!end_of_partition)
+    {
+      if (order_tracker.compare_with_cache_for_null_values())
+        return true;
+    }
+    return false;
+  }
 
 private:
   Group_bound_tracker bound_tracker;
+  Group_bound_tracker order_tracker;
   bool end_of_partition;
 };
 
@@ -1200,7 +1231,7 @@ class Frame_range_n_top : public Frame_cursor
                     SQL_I_List<ORDER> *partition_list,
                     SQL_I_List<ORDER> *order_list,
                     bool is_preceding_arg, Item *n_val_arg) :
-    cursor(thd, partition_list), n_val(n_val_arg), item_add(NULL),
+    cursor(thd, partition_list, NULL), n_val(n_val_arg), item_add(NULL),
     is_preceding(is_preceding_arg)
   {
     DBUG_ASSERT(order_list->elements == 1);
@@ -1339,7 +1370,7 @@ class Frame_range_n_bottom: public Frame_cursor
                        SQL_I_List<ORDER> *partition_list,
                        SQL_I_List<ORDER> *order_list,
                        bool is_preceding_arg, Item *n_val_arg) :
-    cursor(thd, partition_list), n_val(n_val_arg), item_add(NULL),
+    cursor(thd, partition_list, NULL), n_val(n_val_arg), item_add(NULL),
     is_preceding(is_preceding_arg), added_values(false)
   {
     DBUG_ASSERT(order_list->elements == 1);
@@ -1469,7 +1500,7 @@ class Frame_range_current_row_bottom: public Frame_cursor
   Frame_range_current_row_bottom(THD *thd,
                                  SQL_I_List<ORDER> *partition_list,
                                  SQL_I_List<ORDER> *order_list) :
-    cursor(thd, partition_list), peer_tracker(thd, order_list)
+    cursor(thd, partition_list, NULL), peer_tracker(thd, order_list)
   {
   }
 
@@ -1684,7 +1715,7 @@ class Frame_unbounded_following : public Frame_cursor
   Frame_unbounded_following(THD *thd,
       SQL_I_List<ORDER> *partition_list,
       SQL_I_List<ORDER> *order_list) :
-    cursor(thd, partition_list) {}
+    cursor(thd, partition_list, order_list){}
 
   void init(READ_RECORD *info)
   {
@@ -1756,6 +1787,35 @@ class Frame_unbounded_following_set_count : public Frame_unbounded_following
   }
 };
 
+class Frame_unbounded_following_set_count_special : public Frame_unbounded_following_set_count
+{
+public:
+  Frame_unbounded_following_set_count_special(
+      THD *thd,
+      SQL_I_List<ORDER> *partition_list, SQL_I_List<ORDER> *order_list) :
+    Frame_unbounded_following_set_count(thd, partition_list, order_list)
+    {}
+
+  void next_partition(ha_rows rownum)
+  {
+    ha_rows num_rows_in_partition= 0;
+    if (cursor.fetch_func(&num_rows_in_partition))
+      return;
+
+    /* Walk to the end of the partition, find how many rows there are. */
+    while (!cursor.next_func(&num_rows_in_partition));
+
+    List_iterator_fast<Item_sum> it(sum_functions);
+    Item_sum* item;
+    while ((item= it++))
+    {
+      Item_sum_window_with_row_count* item_with_row_count =
+        static_cast<Item_sum_window_with_row_count *>(item);
+      item_with_row_count->set_row_count(num_rows_in_partition);
+    }
+  }
+};
+
 /////////////////////////////////////////////////////////////////////////////
 // ROWS-type frame bounds
 /////////////////////////////////////////////////////////////////////////////
@@ -1953,7 +2013,7 @@ class Frame_n_rows_following : public Frame_cursor
             SQL_I_List<ORDER> *order_list,
             bool is_top_bound_arg, ha_rows n_rows_arg) :
     is_top_bound(is_top_bound_arg), n_rows(n_rows_arg),
-    cursor(thd, partition_list)
+    cursor(thd, partition_list, NULL)
   {
   }
 
@@ -2564,9 +2624,18 @@ void get_window_functions_required_cursors(
     */
     if (item_win_func->requires_partition_size())
     {
-      fc= new Frame_unbounded_following_set_count(thd,
+      if (item_win_func->only_single_element_order_list())
+      {
+        fc= new Frame_unbounded_following_set_count_special(thd,
                 item_win_func->window_spec->partition_list,
                 item_win_func->window_spec->order_list);
+      }
+      else
+      {
+        fc= new Frame_unbounded_following_set_count(thd,
+                item_win_func->window_spec->partition_list,
+                item_win_func->window_spec->order_list);
+      }
       fc->add_sum_func(sum_func);
       cursor_manager->add_cursor(fc);
     }