5.3 merge

1 files changed, 9 insertions, 2 deletions

diff --git a/sql/opt_range.cc b/sql/opt_range.cc
index 3f49e1664f0..823699d14b1 100644
--- a/sql/opt_range.cc
+++ b/sql/opt_range.cc
@@ -132,7 +132,12 @@
 
 static int sel_cmp(Field *f,uchar *a,uchar *b,uint8 a_flag,uint8 b_flag);
 
-static uchar is_null_string[2]= {1,0};
+/*
+  this should be long enough so that any memcmp with a string that
+  starts from '\0' won't cross is_null_string boundaries, even
+  if the memcmp is optimized to compare 4- 8- or 16- bytes at once
+*/
+static uchar is_null_string[20]= {1,0};
 
 class RANGE_OPT_PARAM;
 /*
@@ -7368,8 +7373,10 @@ static SEL_TREE *get_mm_tree(RANGE_OPT_PARAM *param,COND *cond)
     DBUG_RETURN(tree);
   }
   /* Here when simple cond */
-  if (cond->const_item() && !cond->is_expensive())
+  if (cond->const_item())
   {
+    if (cond->is_expensive())
+      DBUG_RETURN(0);
     /*
       During the cond->val_int() evaluation we can come across a subselect 
       item which may allocate memory on the thd->mem_root and assumes