Fixed bug mdev-11745.

Due to this bug many queries that contained a window function
with MIN/MAX aggregation returned wrong results.

Calculation of a MIN/MAX aggregate function uses cache objects
and a comparator object that are created and set up in
Item_sum_hybrid::fix_fields () by a call of Item_sum_hybrid::setup_hybrid().
The latter binds the objects to the first argument of the
MIN/MAX function. Meanwhile window function perform aggregation
over fields of a temporary table. So binding must be done rather to
these fields. The earliest moment when setup the objects used in
MIN/max functions can be done is after all calls of the method
split_sum_func().

This patch introduces this late setup, but only for aggregate
functions used in window functions.
Probably it makes sense to use this late setup for all MIN/MAX
objects.

mysql-test/r/win.result

@@ -2558,3 +2558,199 @@ execute stmt;
 row_number() over (partition by 4 order by 1+2)
 1
 deallocate prepare stmt;
+#
+# MDEV-11745: window function with min/max 
+#
+create table t1 (i int, b int);
+insert into t1 values
+(1,1),(2,1),(3,1),(4,4),(5,4),(6,4),(7,8),(8,8),(9,8),(10,8);
+select b, min(i) over (partition by b) as f 
+from t1 as tt
+order by i;
+b	f
+1	1
+1	1
+1	1
+4	4
+4	4
+4	4
+8	7
+8	7
+8	7
+8	7
+select b, min(i) over (partition by b) as f 
+from (select * from t1) as tt
+order by i;
+b	f
+1	1
+1	1
+1	1
+4	4
+4	4
+4	4
+8	7
+8	7
+8	7
+8	7
+select b, min(i+10) over (partition by b) as f 
+from t1 as tt
+order by i;
+b	f
+1	11
+1	11
+1	11
+4	14
+4	14
+4	14
+8	17
+8	17
+8	17
+8	17
+select b, min(i) over (partition by b) as f 
+from (select i+10 as i, b from t1) as tt
+order by i;
+b	f
+1	11
+1	11
+1	11
+4	14
+4	14
+4	14
+8	17
+8	17
+8	17
+8	17
+select b, min(i+20) over (partition by b) as f 
+from (select i+10 as i, b from t1) as tt
+order by i;
+b	f
+1	31
+1	31
+1	31
+4	34
+4	34
+4	34
+8	37
+8	37
+8	37
+8	37
+select b, max(i) over (partition by b) as f 
+from t1 as tt
+order by i;
+b	f
+1	3
+1	3
+1	3
+4	6
+4	6
+4	6
+8	10
+8	10
+8	10
+8	10
+select b, max(i) over (partition by b) as f 
+from (select * from t1) as tt
+order by i;
+b	f
+1	3
+1	3
+1	3
+4	6
+4	6
+4	6
+8	10
+8	10
+8	10
+8	10
+select b, max(i+10) over (partition by b) as f 
+from t1 as tt
+order by i;
+b	f
+1	13
+1	13
+1	13
+4	16
+4	16
+4	16
+8	20
+8	20
+8	20
+8	20
+select b, max(i) over (partition by b) as f 
+from (select i+10 as i, b from t1) as tt
+order by i;
+b	f
+1	13
+1	13
+1	13
+4	16
+4	16
+4	16
+8	20
+8	20
+8	20
+8	20
+select b, max(i+20) over (partition by b) as f 
+from (select i+10 as i, b from t1) as tt
+order by i;
+b	f
+1	33
+1	33
+1	33
+4	36
+4	36
+4	36
+8	40
+8	40
+8	40
+8	40
+select max(i), max(i), sum(i), count(i)
+from t1 as tt
+group by b;
+max(i)	max(i)	sum(i)	count(i)
+3	3	6	3
+6	6	15	3
+10	10	34	4
+select max(i), min(sum(i)) over (partition by count(i)) f
+from t1 as tt
+group by b;
+max(i)	f
+3	6
+6	6
+10	34
+select max(i), min(sum(i)) over (partition by count(i)) f
+from (select * from t1) as tt
+group by b;
+max(i)	f
+3	6
+6	6
+10	34
+select max(i+10), min(sum(i)+10) over (partition by count(i)) f
+from t1 as tt
+group by b;
+max(i+10)	f
+13	16
+16	16
+20	44
+select max(i), max(i), sum(i), count(i)
+from (select i+10 as i, b from t1) as tt
+group by b;
+max(i)	max(i)	sum(i)	count(i)
+13	13	36	3
+16	16	45	3
+20	20	74	4
+select max(i), min(sum(i)) over (partition by count(i)) f
+from (select i+10 as i, b from t1) as tt
+group by b;
+max(i)	f
+13	36
+16	36
+20	74
+select max(i), min(i), min(max(i)-min(i)) over (partition by count(i)) f
+from (select i+10 as i, b from t1) as tt
+group by b;
+max(i)	min(i)	f
+13	11	2
+16	14	2
+20	17	3
+drop table t1;

mysql-test/r/win_empty_over.result

@@ -138,8 +138,8 @@ create view win_view
 as (select a, max(a + 1) over () from t1 where a = 1);
 select * from win_view;
 a	max(a + 1) over ()
-1	3
-1	3
-1	3
+1	2
+1	2
+1	2
 drop view win_view;
 drop table t1;

mysql-test/t/win.test

@@ -1559,3 +1559,80 @@ execute stmt;
 execute stmt;
 deallocate prepare stmt;
 
+--echo #
+--echo # MDEV-11745: window function with min/max 
+--echo #
+
+create table t1 (i int, b int);
+insert into t1 values
+  (1,1),(2,1),(3,1),(4,4),(5,4),(6,4),(7,8),(8,8),(9,8),(10,8);
+
+select b, min(i) over (partition by b) as f 
+  from t1 as tt
+order by i;
+
+select b, min(i) over (partition by b) as f 
+  from (select * from t1) as tt
+order by i;
+
+select b, min(i+10) over (partition by b) as f 
+  from t1 as tt
+order by i;
+
+select b, min(i) over (partition by b) as f 
+  from (select i+10 as i, b from t1) as tt
+order by i;
+
+select b, min(i+20) over (partition by b) as f 
+  from (select i+10 as i, b from t1) as tt
+order by i;
+
+select b, max(i) over (partition by b) as f 
+  from t1 as tt
+order by i;
+
+select b, max(i) over (partition by b) as f 
+  from (select * from t1) as tt
+order by i;
+
+select b, max(i+10) over (partition by b) as f 
+  from t1 as tt
+order by i;
+
+select b, max(i) over (partition by b) as f 
+  from (select i+10 as i, b from t1) as tt
+order by i;
+
+select b, max(i+20) over (partition by b) as f 
+  from (select i+10 as i, b from t1) as tt
+order by i;
+
+select max(i), max(i), sum(i), count(i)
+  from t1 as tt
+group by b;
+
+select max(i), min(sum(i)) over (partition by count(i)) f
+  from t1 as tt
+group by b;
+
+select max(i), min(sum(i)) over (partition by count(i)) f
+  from (select * from t1) as tt
+group by b;
+
+select max(i+10), min(sum(i)+10) over (partition by count(i)) f
+  from t1 as tt
+group by b;
+
+select max(i), max(i), sum(i), count(i)
+  from (select i+10 as i, b from t1) as tt
+group by b;
+
+select max(i), min(sum(i)) over (partition by count(i)) f
+  from (select i+10 as i, b from t1) as tt
+group by b;
+
+select max(i), min(i), min(max(i)-min(i)) over (partition by count(i)) f
+  from (select i+10 as i, b from t1) as tt
+group by b;
+
+drop table t1;

sql/item_sum.cc

@@ -1161,7 +1161,8 @@ Item_sum_hybrid::fix_fields(THD *thd, Item **ref)
   case TIME_RESULT:
     DBUG_ASSERT(0);
   };
-  setup_hybrid(thd, args[0], NULL);
+  if (!is_window_func_sum_expr())
+    setup_hybrid(thd, args[0], NULL);
   /* MIN/MAX can return NULL for empty set indepedent of the used column */
   maybe_null= 1;
   result_field=0;

sql/item_sum.h

@@ -576,6 +576,8 @@ class Item_sum :public Item_func_or_sum
   bool check_vcol_func_processor(void *arg);
   virtual void setup_window_func(THD *thd, Window_spec *window_spec) {}
   void mark_as_window_func_sum_expr() { window_func_sum_expr_flag= true; }
+  bool is_window_func_sum_expr() { return window_func_sum_expr_flag; }
+  virtual void setup_caches(THD *thd) {};
 };
 
 
@@ -1053,6 +1055,7 @@ class Item_sum_hybrid :public Item_sum, public Type_handler_hybrid_field_type
   void no_rows_in_result();
   void restore_to_before_no_rows_in_result();
   Field *create_tmp_field(bool group, TABLE *table);
+  void setup_caches(THD *thd) { setup_hybrid(thd, arguments()[0], NULL); }
 };
 
 

sql/item_windowfunc.cc

@@ -150,6 +150,7 @@ void Item_window_func::split_sum_func(THD *thd, Ref_ptr_array ref_pointer_array,
     Item **p_item= &window_func()->arguments()[i];
     (*p_item)->split_sum_func2(thd, ref_pointer_array, fields, p_item, flags);
   }
+  window_func()->setup_caches(thd);
 }