Continuation of "Implemented a counter within Item_sum_sum" a few commits before

Query result had 0 where it should have had NULLs:
- Make Item_window_func::val* functions honor NULL-handling conventions:
  1. set null_value to indicate whether we've returned a NULL value
  2. val_str and val_decimal should return NULL pointer when they're
     returning SQL NULL value.

Fix assertion failure when sending results to network.
- The assert was due to window func returing SQL NULL despite having
  maybe_null=false
- Fixed by settting Item_window_func::maybe_null correctly in fix_fields

1 files changed, 1 insertions, 0 deletions

diff --git a/sql/item_windowfunc.cc b/sql/item_windowfunc.cc
index 82e84ab5c36..027b0bdf0a1 100644
--- a/sql/item_windowfunc.cc
+++ b/sql/item_windowfunc.cc
@@ -59,6 +59,7 @@ Item_window_func::fix_fields(THD *thd, Item **ref)
   fix_length_and_dec();
 
   max_length= window_func->max_length;
+  maybe_null= window_func->maybe_null;
 
   fixed= 1;
   force_return_blank= true;