index name shown (SCRUM) (WL#1274)

mysql-test/r/subselect.result:
  index name shown
sql/item_subselect.cc:
  index name shown

mysql-test/r/subselect.result

@@ -876,7 +876,7 @@ 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_subquery	a	a	5	func	2	Using index
 Warnings:
-Note	1003	select high_priority test.t1.a AS `a`,<in_optimizer>(test.t1.a,<exists>(<index_lookup>(<cache>(test.t1.a) in t2 chicking NULL))) AS `t1.a in (select t2.a from t2)` from test.t1
+Note	1003	select high_priority test.t1.a AS `a`,<in_optimizer>(test.t1.a,<exists>(<index_lookup>(<cache>(test.t1.a) in t2 on a chicking NULL))) AS `t1.a in (select t2.a from t2)` from test.t1
 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;
@@ -1308,7 +1308,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	index	NULL	PRIMARY	4	NULL	4	Using where; Using index
 2	DEPENDENT SUBQUERY	t1	unique_subquery	PRIMARY	PRIMARY	4	func	1	Using index
 Warnings:
-Note	1003	select high_priority test.t2.a AS `a` from test.t2 where <in_optimizer>(test.t2.a,<exists>(<primary_index_lookup>(<cache>(test.t2.a) in t1)))
+Note	1003	select high_priority test.t2.a AS `a` from test.t2 where <in_optimizer>(test.t2.a,<exists>(<primary_index_lookup>(<cache>(test.t2.a) in t1 on PRIMARY)))
 select * from t2 where t2.a in (select a from t1 where t1.b <> 30);
 a
 2
@@ -1318,7 +1318,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	index	NULL	PRIMARY	4	NULL	4	Using where; Using index
 2	DEPENDENT SUBQUERY	t1	unique_subquery	PRIMARY	PRIMARY	4	func	1	Using index; Using where
 Warnings:
-Note	1003	select high_priority test.t2.a AS `a` from test.t2 where <in_optimizer>(test.t2.a,<exists>(<primary_index_lookup>(<cache>(test.t2.a) in t1 where (test.t1.b <> 30))))
+Note	1003	select high_priority test.t2.a AS `a` from test.t2 where <in_optimizer>(test.t2.a,<exists>(<primary_index_lookup>(<cache>(test.t2.a) in t1 on PRIMARY where (test.t1.b <> 30))))
 select * from t2 where t2.a in (select t1.a from t1,t3 where t1.b=t3.a);
 a
 2
@@ -1347,7 +1347,7 @@ 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_subquery	a	a	5	func	1001	Using index
 Warnings:
-Note	1003	select high_priority test.t2.a AS `a` from test.t2 where <in_optimizer>(test.t2.a,<exists>(<index_lookup>(<cache>(test.t2.a) in t1)))
+Note	1003	select high_priority test.t2.a AS `a` from test.t2 where <in_optimizer>(test.t2.a,<exists>(<index_lookup>(<cache>(test.t2.a) in t1 on a)))
 select * from t2 where t2.a in (select a from t1 where t1.b <> 30);
 a
 2
@@ -1357,7 +1357,7 @@ 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_subquery	a	a	5	func	1001	Using index; Using where
 Warnings:
-Note	1003	select high_priority test.t2.a AS `a` from test.t2 where <in_optimizer>(test.t2.a,<exists>(<index_lookup>(<cache>(test.t2.a) in t1 where (test.t1.b <> 30))))
+Note	1003	select high_priority test.t2.a AS `a` from test.t2 where <in_optimizer>(test.t2.a,<exists>(<index_lookup>(<cache>(test.t2.a) in t1 on a where (test.t1.b <> 30))))
 select * from t2 where t2.a in (select t1.a from t1,t3 where t1.b=t3.a);
 a
 2
@@ -1384,7 +1384,7 @@ 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_subquery	a	a	5	func	1001	Using index; Using where
 Warnings:
-Note	1003	select high_priority test.t2.a AS `a` from test.t2 where <in_optimizer>(test.t2.a,<exists>(<index_lookup>(<cache>(test.t2.a) in t1 where (test.t1.b <> 30))))
+Note	1003	select high_priority test.t2.a AS `a` from test.t2 where <in_optimizer>(test.t2.a,<exists>(<index_lookup>(<cache>(test.t2.a) in t1 on a where (test.t1.b <> 30))))
 drop table t1, t2, t3;
 create table t1 (a int, b int);
 create table t2 (a int, b int);
@@ -1477,13 +1477,13 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	index	NULL	s1	6	NULL	3	Using index
 2	DEPENDENT SUBQUERY	t2	index_subquery	s1	s1	6	func	2	Using index
 Warnings:
-Note	1003	select high_priority test.t1.s1 AS `s1`,not(<in_optimizer>(test.t1.s1,<exists>(<index_lookup>(<cache>(test.t1.s1) in t2 chicking NULL)))) AS `s1 NOT IN (SELECT s1 FROM t2)` from test.t1
+Note	1003	select high_priority test.t1.s1 AS `s1`,not(<in_optimizer>(test.t1.s1,<exists>(<index_lookup>(<cache>(test.t1.s1) in t2 on s1 chicking NULL)))) AS `s1 NOT IN (SELECT s1 FROM t2)` from test.t1
 explain extended select s1, s1 NOT IN (SELECT s1 FROM t2 WHERE s1 < 'a2') from t1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	index	NULL	s1	6	NULL	3	Using index
 2	DEPENDENT SUBQUERY	t2	index_subquery	s1	s1	6	func	1	Using index; Using where
 Warnings:
-Note	1003	select high_priority test.t1.s1 AS `s1`,not(<in_optimizer>(test.t1.s1,<exists>(<index_lookup>(<cache>(test.t1.s1) in t2 chicking NULL where (test.t2.s1 < _latin1'a2'))))) AS `s1 NOT IN (SELECT s1 FROM t2 WHERE s1 < 'a2')` from test.t1
+Note	1003	select high_priority test.t1.s1 AS `s1`,not(<in_optimizer>(test.t1.s1,<exists>(<index_lookup>(<cache>(test.t1.s1) in t2 on s1 chicking NULL where (test.t2.s1 < _latin1'a2'))))) AS `s1 NOT IN (SELECT s1 FROM t2 WHERE s1 < 'a2')` from test.t1
 drop table t1,t2;
 create table t2 (a int, b int);
 create table t3 (a int);

sql/item_subselect.cc

@@ -1263,6 +1263,9 @@ void subselect_uniquesubquery_engine::print(String *str)
   tab->ref.items[0]->print(str);
   str->append(" in ");
   str->append(tab->table->real_name);
+  KEY *key_info= tab->table->key_info+ tab->ref.key;
+  str->append(" on ");
+  str->append(key_info->name);
   if (cond)
   {
     str->append(" where ");
@@ -1278,6 +1281,9 @@ void subselect_indexsubquery_engine::print(String *str)
   tab->ref.items[0]->print(str);
   str->append(" in ");
   str->append(tab->table->real_name);
+  KEY *key_info= tab->table->key_info+ tab->ref.key;
+  str->append(" on ");
+  str->append(key_info->name);
   if (check_null)
     str->append(" chicking NULL");
     if (cond)