Fixed bug in datetime range optimization

Docs/manual.texi:
  Changelog
mysql-test/r/type_datetime.result:
  Test of datetime optimization
mysql-test/t/type_datetime.test:
  Test of datetime optimization

2 files changed, 21 insertions, 2 deletions

diff --git a/sql/item.h b/sql/item.h
index 41b897956db..b8903756027 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -342,6 +342,25 @@ public:
 };
 
 
+/*
+  The following class is used to optimize comparing of date columns
+  We need to save the original item, to be able to set the field to the
+  original value in 'opt_range'.
+*/
+
+class Item_int_with_ref :public Item_int
+{
+  Item *ref;
+public:
+  Item_int_with_ref(longlong i, Item *ref_arg) :Item_int(i), ref(ref_arg)
+  {}
+  bool save_in_field(Field *field)
+  {
+    return ref->save_in_field(field);
+  }
+};
+
+
 #include "item_sum.h"
 #include "item_func.h"
 #include "item_cmpfunc.h"
diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index 73821f8d826..ae50090fea1 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -45,8 +45,8 @@ static bool convert_constant_item(Field *field, Item **item)
     (*item)->save_in_field(field);
     if (!((*item)->null_value))
     {
-      Item *tmp=new Item_int(field->val_int());
-      if ((tmp))
+      Item *tmp=new Item_int_with_ref(field->val_int(), *item);
+      if (tmp)
 	*item=tmp;
       return 1;
     }