MDEV-18015: Assertion `global_status_var.global_memory_used == 0' failed when...

MDEV-18015: Assertion `global_status_var.global_memory_used == 0' failed when using UDF , window functions and views

Adding destructor for Group_bound_tracker to free Cached_item_str.
The Cached_item for window functions are allocated on THD:mem_root
but the Cached_item_str has value of type string which is allocated on
the heap, so we need to call free() for it

mysql-test/r/win.result

@@ -3607,5 +3607,32 @@ b	row_number() over (partition by sum(a)+1)
 2000	1
 drop table t1;
 #
+# MDEV-18015: Assertion `global_status_var.global_memory_used == 0' failed when using UDF,
+# window functions and views
+#
+create table t1 (id int, n1 int);
+insert into t1 values (1,1),(2,1),(3,2),(4,4);
+explain
+select max(n1) over (partition by 'abc') from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using temporary
+select max(n1) over (partition by 'abc') from t1;
+max(n1) over (partition by 'abc')
+4
+4
+4
+4
+explain
+select rank() over (partition by 'abc' order by 'xyz') from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using temporary
+select rank() over (partition by 'abc' order by 'xyz') from t1;
+rank() over (partition by 'abc' order by 'xyz')
+1
+1
+1
+1
+drop table t1;
+#
 # End of 10.2 tests
 #

mysql-test/t/win.test

@@ -2325,6 +2325,22 @@ select b, row_number() over (partition by sum(a)+1) from t1 group by b;
 
 drop table t1;
 
+--echo #
+--echo # MDEV-18015: Assertion `global_status_var.global_memory_used == 0' failed when using UDF,
+--echo # window functions and views
+--echo #
+
+create table t1 (id int, n1 int);
+insert into t1 values (1,1),(2,1),(3,2),(4,4);
+explain
+select max(n1) over (partition by 'abc') from t1;
+select max(n1) over (partition by 'abc') from t1;
+
+explain
+select rank() over (partition by 'abc' order by 'xyz') from t1;
+select rank() over (partition by 'abc' order by 'xyz') from t1;
+drop table t1;
+
 --echo #
 --echo # End of 10.2 tests
 --echo #

sql/item_windowfunc.h

@@ -28,11 +28,6 @@ class Group_bound_tracker
     first_check= true;
   }
 
-  void cleanup()
-  {
-    group_fields.empty();
-  }
-
   /*
     Check if the current row is in a different group than the previous row
     this function was called for.
@@ -70,6 +65,10 @@ class Group_bound_tracker
     }
     return 0;
   }
+  ~Group_bound_tracker()
+  {
+    group_fields.delete_elements();
+  }
 
 private:
   List<Cached_item> group_fields;
@@ -199,7 +198,6 @@ class Item_sum_rank: public Item_sum_int
   {
     if (peer_tracker)
     {
-      peer_tracker->cleanup();
       delete peer_tracker;
       peer_tracker= NULL;
     }
@@ -269,7 +267,6 @@ class Item_sum_dense_rank: public Item_sum_int
   {
     if (peer_tracker)
     {
-      peer_tracker->cleanup();
       delete peer_tracker;
       peer_tracker= NULL;
     }
@@ -537,7 +534,6 @@ class Item_sum_percent_rank: public Item_sum_window_with_row_count
   {
     if (peer_tracker)
     {
-      peer_tracker->cleanup();
       delete peer_tracker;
       peer_tracker= NULL;
     }