MDEV-20278 PERCENTILE_DISC() returns a wrong data type

3 files changed, 10 insertions, 17 deletions

diff --git a/sql/item_windowfunc.cc b/sql/item_windowfunc.cc
index 2db396d3065..85e5144779e 100644
--- a/sql/item_windowfunc.cc
+++ b/sql/item_windowfunc.cc
@@ -174,7 +174,8 @@ bool Item_window_func::check_result_type_of_order_item()
 {
   if (only_single_element_order_list())
   {
-    Item_result rtype= window_spec->order_list->first->item[0]->cmp_type();
+    Item *src_item= window_spec->order_list->first->item[0];
+    Item_result rtype= src_item->cmp_type();
     // TODO (varun) : support date type in percentile_cont function
     if (rtype != REAL_RESULT && rtype != INT_RESULT &&
         rtype != DECIMAL_RESULT && rtype != TIME_RESULT)
@@ -182,7 +183,14 @@ bool Item_window_func::check_result_type_of_order_item()
       my_error(ER_WRONG_TYPE_FOR_PERCENTILE_FUNC, MYF(0), window_func()->func_name());
       return TRUE;
     }
-    setting_handler_for_percentile_functions(rtype);
+    if (window_func()->sum_func() == Item_sum::PERCENTILE_DISC_FUNC)
+    {
+      Item_sum_percentile_disc *func=
+        static_cast<Item_sum_percentile_disc*>(window_func());
+      func->set_handler(src_item->type_handler());
+      func->Type_std_attributes::set(src_item);
+      Type_std_attributes::set(src_item);
+    }
   }
   return FALSE;
 }
diff --git a/sql/item_windowfunc.h b/sql/item_windowfunc.h
index 37376501d1f..1432643dfc8 100644
--- a/sql/item_windowfunc.h
+++ b/sql/item_windowfunc.h
@@ -1097,17 +1097,6 @@ public:
     }
   }
 
-  void setting_handler_for_percentile_functions(Item_result rtype) const
-  {
-    switch (window_func()->sum_func()){
-    case Item_sum::PERCENTILE_DISC_FUNC:
-         ((Item_sum_percentile_disc* ) window_func())->set_handler_by_cmp_type(rtype);
-         break;
-    default:
-      return;
-    }
-  }
-
   bool check_result_type_of_order_item();
 
 
diff --git a/sql/sql_type.h b/sql/sql_type.h
index 3ef210efecf..a7915ddc463 100644
--- a/sql/sql_type.h
+++ b/sql/sql_type.h
@@ -3506,10 +3506,6 @@ public:
   {
     return (m_type_handler= Type_handler::get_handler_by_result_type(type));
   }
-  const Type_handler *set_handler_by_cmp_type(Item_result type)
-  {
-    return (m_type_handler= Type_handler::get_handler_by_cmp_type(type));
-  }
   const Type_handler *set_handler_by_result_type(Item_result type,
                                                  uint max_octet_length,
                                                  CHARSET_INFO *cs)