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

3 files changed, 47 insertions, 8 deletions

diff --git a/mysql-test/r/win.result b/mysql-test/r/win.result
index 5da8a7f8a3c..13d452f3ef2 100644
--- a/mysql-test/r/win.result
+++ b/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
 #
diff --git a/mysql-test/t/win.test b/mysql-test/t/win.test
index 15c48c31250..a4d42ce2b91 100644
--- a/mysql-test/t/win.test
+++ b/mysql-test/t/win.test
@@ -2326,5 +2326,21 @@ 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 #
diff --git a/sql/item_windowfunc.h b/sql/item_windowfunc.h
index 21270733051..b9df1b7482b 100644
--- a/sql/item_windowfunc.h
+++ b/sql/item_windowfunc.h
@@ -28,11 +28,6 @@ public:
     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 @@ public:
     }
     return 0;
   }
+  ~Group_bound_tracker()
+  {
+    group_fields.delete_elements();
+  }
 
 private:
   List<Cached_item> group_fields;
@@ -199,7 +198,6 @@ public:
   {
     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;
     }