Added value field to Item_sum_percentile_disc

Check for single element in the order_list is added

sql/item_windowfunc.cc

@@ -108,6 +108,17 @@ Item_window_func::fix_fields(THD *thd, Item **ref)
     my_error(ER_NO_ORDER_LIST_IN_WINDOW_SPEC, MYF(0), window_func()->func_name());
     return true;
   }
+
+  if (only_single_element_order_list())
+  {
+    // need to change the error, the error should say that we have more than one element in the order list
+    if (window_spec->order_list->elements != 1)
+    {
+      my_error(ER_NO_ORDER_LIST_IN_WINDOW_SPEC, MYF(0), window_func()->func_name());
+      return true;
+    }
+  }
+
   /*
     TODO: why the last parameter is 'ref' in this call? What if window_func
     decides to substitute itself for something else and does *ref=.... ? 
@@ -194,6 +205,11 @@ void Item_sum_dense_rank::setup_window_func(THD *thd, Window_spec *window_spec)
   clear();
 }
 
+void Item_sum_percentile_disc::setup_window_func(THD *thd, Window_spec *window_spec)
+{
+  setup_percentile_func(thd, window_spec->order_list);
+}
+
 bool Item_sum_dense_rank::add()
 {
   if (peer_tracker->check_if_next_group() || first_add)

sql/item_windowfunc.h

@@ -705,7 +705,7 @@ class Item_sum_percentile_disc : public Item_sum_cume_dist
 {
 public:
   Item_sum_percentile_disc(THD *thd, Item* arg) : Item_sum_cume_dist(thd, arg)
-                                 {}
+                              value(NULL) {}
 
   double val_real()
   {
@@ -753,7 +753,23 @@ class Item_sum_percentile_disc : public Item_sum_cume_dist
 
   Item *get_copy(THD *thd, MEM_ROOT *mem_root)
   { return get_item_copy<Item_sum_percentile_disc>(thd, mem_root, this); }
+  void setup_window_func(THD *thd, Window_spec *window_spec);
+  void setup_percentile_func(THD *thd, SQL_I_List<ORDER> *list)
+  {
+    value= new_Cached_item(thd, list->first->item[0], FALSE);
+  }
+  void cleanup()
+  {
+    if (value)
+    {
+      delete value;
+      value= NULL;
+    }
+    Item_sum_num::cleanup();
+  }
 
+private:
+  Cached_item *value;
 };
 
 
@@ -871,6 +887,17 @@ class Item_window_func : public Item_func_or_sum
     }
   }  
 
+  bool only_single_element_order_list() const
+  {
+    switch(window_func()->sum_func()){
+    case Item_sum::PERCENTILE_CONT_FUNC:
+    case Item_sum::PERCENTILE_DISC_FUNC:
+      return true;
+    default:
+      return false;
+    }
+  }
+
   /*
     Computation functions.
     TODO: consoder merging these with class Group_bound_tracker.