1 files changed, 5 insertions, 1 deletions
diff --git a/sql/item_cmpfunc.h b/sql/item_cmpfunc.h
index 7bdc90adcee..1d85d08c434 100644
--- a/sql/item_cmpfunc.h
+++ b/sql/item_cmpfunc.h
@@ -965,6 +965,10 @@ class Item_func_in :public Item_func_opt_neg
 {
 public:
   Item_result cmp_type;
+  /* 
+    an array of values when the right hand arguments of IN
+    are all SQL constant and there are no nulls 
+  */
   in_vector *array;
   cmp_item *in_item;
   bool have_null;
@@ -990,7 +994,7 @@ public:
     DBUG_VOID_RETURN;
   }
   optimize_type select_optimize() const
-    { return array ? OPTIMIZE_KEY : OPTIMIZE_NONE; }
+    { return OPTIMIZE_KEY; }
   void print(String *str);
   enum Functype functype() const { return IN_FUNC; }
   const char *func_name() const { return " IN "; }