cleunup() of count() and max()/min() added (BUG#2687)

mysql-test/r/func_group.result:
  test of optimized aggregate function re-execution
mysql-test/t/func_group.test:
  test of optimized aggregate function re-execution
sql/item_sum.cc:
  cleunup() added
sql/item_sum.h:
  cleunup() added

mysql-test/r/func_group.result

@@ -656,3 +656,31 @@ select stddev(2) from t1;
 stddev(2)
 NULL
 drop table t1;
+create table t1 (a int);
+insert into t1 values (1),(2);
+prepare stmt1 from 'SELECT COUNT(*) FROM t1';
+execute stmt1;
+COUNT(*)
+2
+execute stmt1;
+COUNT(*)
+2
+execute stmt1;
+COUNT(*)
+2
+deallocate prepare stmt1;
+drop table t1;
+create table t1 (a int, primary key(a));
+insert into t1 values (1),(2);
+prepare stmt1 from 'SELECT max(a) FROM t1';
+execute stmt1;
+max(a)
+2
+execute stmt1;
+max(a)
+2
+execute stmt1;
+max(a)
+2
+deallocate prepare stmt1;
+drop table t1;

mysql-test/t/func_group.test

@@ -396,3 +396,25 @@ create table t1 (a int);
 select variance(2) from t1;
 select stddev(2) from t1;
 drop table t1;
+
+
+#
+# cleunup() of optimized away count(*) and max/min
+#
+create table t1 (a int);
+insert into t1 values (1),(2);
+prepare stmt1 from 'SELECT COUNT(*) FROM t1';
+execute stmt1;
+execute stmt1;
+execute stmt1;
+deallocate prepare stmt1;
+drop table t1;
+
+create table t1 (a int, primary key(a));
+insert into t1 values (1),(2);
+prepare stmt1 from 'SELECT max(a) FROM t1';
+execute stmt1;
+execute stmt1;
+execute stmt1;
+deallocate prepare stmt1;
+drop table t1;

sql/item_sum.cc

@@ -361,6 +361,16 @@ longlong Item_sum_count::val_int()
   return (longlong) count;
 }
 
+
+void Item_sum_count::cleanup()
+{
+  DBUG_ENTER("Item_sum_count::cleanup");
+  Item_sum_int::cleanup();
+  used_table_cache= ~(table_map) 0;
+  DBUG_VOID_RETURN;
+}
+
+
 /*
   Avgerage
 */
@@ -575,6 +585,15 @@ Item_sum_hybrid::val_str(String *str)
 }
 
 
+void Item_sum_hybrid::cleanup()
+{
+  DBUG_ENTER("Item_sum_hybrid::cleanup");
+  Item_sum::cleanup();
+  used_table_cache= ~(table_map) 0;
+  DBUG_VOID_RETURN;
+}
+
+
 Item *Item_sum_min::copy_or_same(THD* thd)
 {
   return new (&thd->mem_root) Item_sum_min(thd, this);

sql/item_sum.h

@@ -172,6 +172,7 @@ class Item_sum_count :public Item_sum_int
   void make_const(longlong count_arg) { count=count_arg; used_table_cache=0; }
   longlong val_int();
   void reset_field();
+  void cleanup();
   void update_field();
   const char *func_name() const { return "count"; }
   Item *copy_or_same(THD* thd);
@@ -428,6 +429,7 @@ class Item_sum_hybrid :public Item_sum
   void min_max_update_str_field();
   void min_max_update_real_field();
   void min_max_update_int_field();
+  void cleanup();
 };