Fixed the bug mdev-7599.

At some conditions the function opt_sum_query() can apply MIN/MAX
optimizations to to Item_sum objects of a select These optimizations
becomes invalid if this select is the subquery of an IN subquery
predicate that is converted to a EXISTS subquery. Thus in this case
the MIX/MAX optimizations that have been applied in opt_sum_query()
must be rolled back.
This bug appeared in 5.3 when the code for the cost base choice between
materialization and in-to-exists transformation of non-correlated
IN subqueries was introduced. Before this code in-to-exists
transformations were always performed before the call of opt_sum_query().

1 files changed, 1 insertions, 0 deletions

diff --git a/sql/item_sum.h b/sql/item_sum.h
index 86093f5d4f5..dcc3e494f82 100644
--- a/sql/item_sum.h
+++ b/sql/item_sum.h
@@ -454,6 +454,7 @@ public:
     used_tables_cache= 0; 
     forced_const= TRUE; 
   }
+  void reset_forced_const() { forced_const= FALSE; }
   virtual bool const_item() const { return forced_const; }
   virtual bool const_during_execution() const { return false; }
   virtual void print(String *str, enum_query_type query_type);