From 31f1541f1e367f6eb91f948c4e814bb6554e6b78 Mon Sep 17 00:00:00 2001
From: Varun Gupta <varunraiko1803@gmail.com>
Date: Mon, 26 Jun 2017 03:53:27 +0530
Subject: [PATCH] Setting handler to have the return type as that of the
 element by which we are ordering the partition

---
 sql/item.h             |  2 +-
 sql/item_windowfunc.cc |  5 +++++
 sql/item_windowfunc.h  | 12 ++++++++----
 sql/sql_window.cc      |  4 ++++
 4 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/sql/item.h b/sql/item.h
index 68d09577dcc..0e7582a9ac4 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -5386,7 +5386,7 @@ public:
   Cached_item_decimal(Item *item_par);
   bool cmp(void);
   int  cmp_read_only();
-  my_decimal get_value(){ return value;};
+  my_decimal *get_value(){ return &value;};
   void clear()
   {
     null_value= false;
diff --git a/sql/item_windowfunc.cc b/sql/item_windowfunc.cc
index 50a8c5d82cd..5e77132ad38 100644
--- a/sql/item_windowfunc.cc
+++ b/sql/item_windowfunc.cc
@@ -210,6 +210,11 @@ void Item_sum_percentile_disc::setup_window_func(THD *thd, Window_spec *window_s
   setup_percentile_func(thd, window_spec->order_list);
 }
 
+void Item_sum_percentile_disc::set_type_handler(Window_spec *window_spec)
+{
+  type_handler()->get_handler_by_cmp_type(window_spec->order_list->first->item[0]->result_type());
+}
+
 bool Item_sum_dense_rank::add()
 {
   if (peer_tracker->check_if_next_group() || first_add)
diff --git a/sql/item_windowfunc.h b/sql/item_windowfunc.h
index 6595012fabf..9087404ea3e 100644
--- a/sql/item_windowfunc.h
+++ b/sql/item_windowfunc.h
@@ -701,11 +701,13 @@ class Item_sum_ntile : public Item_sum_window_with_row_count
   ulong current_row_count_;
 };
 
-class Item_sum_percentile_disc : public Item_sum_cume_dist
+class Item_sum_percentile_disc : public Item_sum_cume_dist,
+                                 public Type_handler_hybrid_field_type
 {
 public:
   Item_sum_percentile_disc(THD *thd, Item* arg) : Item_sum_cume_dist(thd, arg),
-                              value(NULL), val_calculated(FALSE) {}
+                           Type_handler_hybrid_field_type(&type_handler_longlong),
+                           value(NULL), val_calculated(FALSE) {}
 
   double val_real()
   {
@@ -715,7 +717,7 @@ public:
       return 0;
     }
     null_value= false;
-    return ((Cached_item_int*) value)->get_value();
+    return ((Cached_item_real*) value)->get_value();
   }
 
   longlong val_int()
@@ -769,7 +771,9 @@ public:
   }
 
   void update_field() {}
-  const Type_handler *type_handler() const { return &type_handler_double; }
+  void set_type_handler(Window_spec *window_spec);
+  const Type_handler *type_handler() const
+  {return Type_handler_hybrid_field_type::type_handler();}
 
   void fix_length_and_dec()
   {
diff --git a/sql/sql_window.cc b/sql/sql_window.cc
index a4c558b52b6..dc8c66120ff 100644
--- a/sql/sql_window.cc
+++ b/sql/sql_window.cc
@@ -319,6 +319,10 @@ setup_windows(THD *thd, Ref_ptr_array ref_pointer_array, TABLE_LIST *tables,
   while ((win_func_item= li++))
   {
     win_func_item->update_used_tables();
+    if (win_func_item->only_single_element_order_list())
+    {
+      ((Item_sum_percentile_disc*)win_func_item)->set_type_handler(win_func_item->window_spec);
+    }
   }
 
   DBUG_RETURN(0);