fixed bug in used_tables() report of left expression of IN subquery

fixed number of rows of external field reported to optimizer
added check of choosen key (checked left expression tag)
(SCRUM fix for simple IN optimisation)

mysql-test/r/subselect.result

@@ -828,7 +828,7 @@ a	t1.a in (select t2.a from t2)
 explain SELECT t1.a, t1.a in (select t2.a from t2) FROM t1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	index	NULL	PRIMARY	4	NULL	4	Using index
-2	DEPENDENT SUBQUERY	t2	index_in	a	a	5	const	2	Using where; Using index
+2	DEPENDENT SUBQUERY	t2	index_in	a	a	5	func	2	Using where; Using index
 CREATE TABLE t3 (a int(11) default '0');
 INSERT INTO t3 VALUES (1),(2),(3);
 SELECT t1.a, t1.a in (select t2.a from t2,t3 where t3.a=t2.a) FROM t1;
@@ -840,7 +840,7 @@ a	t1.a in (select t2.a from t2,t3 where t3.a=t2.a)
 explain SELECT t1.a, t1.a in (select t2.a from t2,t3 where t3.a=t2.a) FROM t1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	index	NULL	PRIMARY	4	NULL	4	Using index
-2	DEPENDENT SUBQUERY	t2	ref_or_null	a	a	5	const	2	Using where; Using index
+2	DEPENDENT SUBQUERY	t2	ref_or_null	a	a	5	func	2	Using where; Using index
 2	DEPENDENT SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	3	Using where
 drop table t1,t2,t3;
 create table t1 (a float);
@@ -1272,7 +1272,7 @@ a
 explain select * from t2 where t2.a in (select a from t1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	index	NULL	a	5	NULL	4	Using where; Using index
-2	DEPENDENT SUBQUERY	t1	index_in	a	a	5	func	100	Using index
+2	DEPENDENT SUBQUERY	t1	index_in	a	a	5	func	1001	Using index
 select * from t2 where t2.a in (select a from t1 where t1.b <> 30);
 a
 2
@@ -1280,7 +1280,7 @@ a
 explain select * from t2 where t2.a in (select a from t1 where t1.b <> 30);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	index	NULL	a	5	NULL	4	Using where; Using index
-2	DEPENDENT SUBQUERY	t1	index_in	a	a	5	func	100	Using index; Using where
+2	DEPENDENT SUBQUERY	t1	index_in	a	a	5	func	1001	Using index; Using where
 select * from t2 where t2.a in (select t1.a from t1,t3 where t1.b=t3.a);
 a
 2
@@ -1289,7 +1289,7 @@ explain select * from t2 where t2.a in (select t1.a from t1,t3 where t1.b=t3.a);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	index	NULL	a	5	NULL	4	Using where; Using index
 2	DEPENDENT SUBQUERY	t3	index	a	a	5	NULL	3	Using index
-2	DEPENDENT SUBQUERY	t1	ref	a	a	10	func,test.t3.a	100	Using where; Using index
+2	DEPENDENT SUBQUERY	t1	ref	a	a	10	func,test.t3.a	1000	Using where; Using index
 insert into t1 values (3,31);
 select * from t2 where t2.a in (select a from t1 where t1.b <> 30);
 a
@@ -1303,7 +1303,7 @@ a
 explain select * from t2 where t2.a in (select a from t1 where t1.b <> 30);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	index	NULL	a	5	NULL	4	Using where; Using index
-2	DEPENDENT SUBQUERY	t1	index_in	a	a	5	func	100	Using index; Using where
+2	DEPENDENT SUBQUERY	t1	index_in	a	a	5	func	1001	Using index; Using where
 drop table t1, t2, t3;
 create table t1 (a int, b int);
 create table t2 (a int, b int);

sql/item_cmpfunc.cc

@@ -380,22 +380,7 @@ bool Item_in_optimizer::fix_left(THD *thd,
       (!cache && !(cache= Item_cache::get_cache(args[0]->result_type()))))
     return 1;
   cache->setup(args[0]);
-  return 0;
-}
-
-
-
-bool Item_in_optimizer::fix_fields(THD *thd, struct st_table_list *tables,
-				   Item ** ref)
-{
-  if (fix_left(thd, tables, ref))
-    return 1;
-  if (args[0]->maybe_null)
-    maybe_null=1;
-
-  with_sum_func= args[0]->with_sum_func;
-  used_tables_cache= args[0]->used_tables();
-  const_item_cache= args[0]->const_item();
+  cache->store(args[0]);
   if (cache->cols() == 1)
   {
     if (args[0]->used_tables())
@@ -414,6 +399,22 @@ bool Item_in_optimizer::fix_fields(THD *thd, struct st_table_list *tables,
 	((Item_cache *)cache->el(i))->set_used_tables(0);
     }
   }
+  return 0;
+}
+
+
+
+bool Item_in_optimizer::fix_fields(THD *thd, struct st_table_list *tables,
+				   Item ** ref)
+{
+  if (fix_left(thd, tables, ref))
+    return 1;
+  if (args[0]->maybe_null)
+    maybe_null=1;
+
+  with_sum_func= args[0]->with_sum_func;
+  used_tables_cache= args[0]->used_tables();
+  const_item_cache= args[0]->const_item();
   if (!args[1]->fixed && args[1]->fix_fields(thd, tables, args))
     return 1;
   Item_in_subselect * sub= (Item_in_subselect *)args[1];

sql/item_subselect.cc

@@ -518,7 +518,7 @@ Item_in_subselect::single_value_transformer(JOIN *join,
     */
     expr= new Item_ref((Item**)optimizer->get_cache(), 
 		       (char *)"<no matter>",
-		       (char *)"<left expr>");
+		       (char *)in_left_expr_name);
 
     unit->dependent= 1;
   }
@@ -694,7 +694,7 @@ Item_in_subselect::row_value_transformer(JOIN *join,
       Item_bool_func2::eq_creator(new Item_ref((*optimizer->get_cache())->
 					       addr(i), 
 					       (char *)"<no matter>",
-					       (char *)"<left expr>"),
+					       (char *)in_left_expr_name),
 				  func);
     item= and_items(item, func);
   }

sql/item_subselect.h

@@ -192,7 +192,7 @@ class Item_exists_subselect :public Item_subselect
 class Item_in_subselect :public Item_exists_subselect
 {
 protected:
-  Item * left_expr;
+  Item *left_expr;
   /*
     expr & optimizer used in subselect rewriting to store Item for
     all JOIN in UNION

sql/mysql_priv.h

@@ -705,6 +705,7 @@ extern const char *command_name[];
 extern const char *first_keyword, *localhost, *delayed_user, *binary_keyword;
 extern const char **errmesg;			/* Error messages */
 extern const char *myisam_recover_options_str;
+extern const char *in_left_expr_name;
 extern uchar *days_in_month;
 extern char language[LIBLEN],reg_ext[FN_EXTLEN];
 extern char glob_hostname[FN_REFLEN], mysql_home[FN_REFLEN];

sql/mysqld.cc

@@ -316,6 +316,8 @@ char *my_bind_addr_str;
 const char **errmesg;			/* Error messages */
 const char *myisam_recover_options_str="OFF";
 const char *sql_mode_str="OFF";
+/* name of reference on left espression in rewritten IN subquery */
+const char *in_left_expr_name= "<left expr>";
 
 FILE *bootstrap_file;
 

sql/sql_select.cc

@@ -772,7 +772,8 @@ JOIN::optimize()
     if (!having)
     {
       Item *where= 0;
-      if (join_tab[0].type == JT_EQ_REF)
+      if (join_tab[0].type == JT_EQ_REF &&
+	  join_tab[0].ref.items[0]->name == in_left_expr_name)
       {
 	if (test_in_subselect(&where))
 	{
@@ -785,7 +786,8 @@ JOIN::optimize()
 								  where)));
 	}
       }
-      else if (join_tab[0].type == JT_REF)
+      else if (join_tab[0].type == JT_REF &&
+	       join_tab[0].ref.items[0]->name == in_left_expr_name)
       {
 	if (test_in_subselect(&where))
 	{
@@ -800,6 +802,7 @@ JOIN::optimize()
 	}
       }
     } else if (join_tab[0].type == JT_REF_OR_NULL &&
+	       join_tab[0].ref.items[0]->name == in_left_expr_name &&
 	       having->type() == Item::FUNC_ITEM &&
 	       ((Item_func *) having)->functype() ==
 	       Item_func::ISNOTNULLTEST_FUNC)
@@ -2347,7 +2350,8 @@ sort_keyuse(KEYUSE *a,KEYUSE *b)
   if (a->keypart != b->keypart)
     return (int) (a->keypart - b->keypart);
   // Place const values before other ones
-  if ((res= test(a->used_tables) - test(b->used_tables)))
+  if ((res= test((a->used_tables & ~OUTER_REF_TABLE_BIT)) -
+       test((b->used_tables & ~OUTER_REF_TABLE_BIT))))
     return res;
   /* Place rows that are not 'OPTIMIZE_REF_OR_NULL' first */
   return (int) ((a->optimize & KEY_OPTIMIZE_REF_OR_NULL) -
@@ -2478,6 +2482,12 @@ static void optimize_keyuse(JOIN *join, DYNAMIC_ARRAY *keyuse_array)
 	keyuse->ref_table_rows= max(tmp_table->file->records, 100);
       }
     }
+    /*
+      Outer reference (external field) is constant for single executing
+      of subquery
+    */
+    if (keyuse->used_tables == OUTER_REF_TABLE_BIT)
+      keyuse->ref_table_rows= 1;
   }
 }