bug #27531: 5.1 part of the fix:

 - added join cache indication in EXPLAIN (Extra column).
 - prefer filesort over full scan over 
   index for ORDER BY (because it's faster).
 - when switching from REF to RANGE because
   RANGE uses longer key turn off sort on
   the head table only as the resulting 
   RANGE access is a candidate for join cache
   and we don't want to disable it by sorting
   on the first table only. 


mysql-test/r/archive_gis.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/compress.result:
  bug #27531:
   - join cache in EXPLAIN. 
   - prefer filesort over full scan over index for ORDER BY.
mysql-test/r/ctype_utf8.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/derived.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/distinct.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/func_group.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/func_group_innodb.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/gis.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/greedy_optimizer.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/group_by.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/group_min_max.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/index_merge_myisam.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/information_schema.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/innodb_gis.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/innodb_mysql.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/join.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/join_nested.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/key_diff.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/myisam.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/ndb_condition_pushdown.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/ndb_gis.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/range.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/row.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/select.result:
  bug #27531:
   - join cache in EXPLAIN.
   - prefer filesort over full scan over index for ORDER BY.
mysql-test/r/ssl.result:
  bug #27531:
   - join cache in EXPLAIN.
   - prefer filesort over full scan over index for ORDER BY.
mysql-test/r/ssl_compress.result:
  bug #27531:
   - join cache in EXPLAIN.
   - prefer filesort over full scan over index for ORDER BY.
mysql-test/r/subselect.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/subselect3.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/union.result:
  bug #27531: join cache in EXPLAIN
mysql-test/r/view.result:
  bug #27531: join cache in EXPLAIN
sql/sql_select.cc:
  bug #27531:
   - join cache in EXPLAIN.
   - prefer filesort over full scan over
     index for ORDER BY.
   - disable sorting on the first table only
     when switching from REF to RANGE.

mysql-test/r/archive_gis.result

@@ -402,7 +402,7 @@ Equals(g1.g, g2.g) as e, Disjoint(g1.g, g2.g) as d, Touches(g1.g, g2.g) as t,
 Intersects(g1.g, g2.g) as i, Crosses(g1.g, g2.g) as r
 FROM gis_geometrycollection g1, gis_geometrycollection g2 ORDER BY first, second;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	g1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using temporary; Using filesort
+1	SIMPLE	g1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using temporary; Using filesort; Using join cache
 1	SIMPLE	g2	ALL	NULL	NULL	NULL	NULL	2	100.00	
 Warnings:
 Note	1003	select `test`.`g1`.`fid` AS `first`,`test`.`g2`.`fid` AS `second`,within(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `w`,contains(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `c`,overlaps(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `o`,equals(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `e`,disjoint(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `d`,touches(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `t`,intersects(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `i`,crosses(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `r` from `test`.`gis_geometrycollection` `g1` join `test`.`gis_geometrycollection` `g2` order by `test`.`g1`.`fid`,`test`.`g2`.`fid`

mysql-test/r/compress.result

@@ -611,11 +611,11 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t3	ref	period	period	4	test.t1.period	4181	
 explain select * from t3 as t1,t3 where t1.period=t3.period order by t3.period limit 10;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t3	index	period	period	4	NULL	41810	
+1	SIMPLE	t3	ALL	period	NULL	NULL	NULL	41810	Using filesort
 1	SIMPLE	t1	ref	period	period	4	test.t3.period	4181	
 explain select * from t3 as t1,t3 where t1.period=t3.period order by t1.period limit 10;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	period	period	4	NULL	41810	
+1	SIMPLE	t1	ALL	period	NULL	NULL	NULL	41810	Using filesort
 1	SIMPLE	t3	ref	period	period	4	test.t1.period	4181	
 select period from t1;
 period
@@ -1434,7 +1434,7 @@ companynr	companynr
 41	40
 explain select distinct t2.companynr,t4.companynr from t2,t4 where t2.companynr=t4.companynr+1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t4	index	NULL	PRIMARY	1	NULL	12	Using index; Using temporary
+1	SIMPLE	t4	index	NULL	PRIMARY	1	NULL	12	Using index; Using temporary; Using join cache
 1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	1199	Using where
 select t2.fld1,t2.companynr,fld3,period from t3,t2 where t2.fld1 = 38208 and t2.fld1=t3.t2nr and period = 1008 or t2.fld1 = 38008 and t2.fld1 =t3.t2nr and period = 1008;
 fld1	companynr	fld3	period

mysql-test/r/ctype_utf8.result

@@ -1454,7 +1454,7 @@ insert into t1 values ('123'), ('456');
 explain
 select substr(Z.a,-1), Z.a from t1 as Y join t1 as Z on Y.a=Z.a order by 1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	Y	ALL	NULL	NULL	NULL	NULL	2	Using temporary; Using filesort
+1	SIMPLE	Y	ALL	NULL	NULL	NULL	NULL	2	Using temporary; Using filesort; Using join cache
 1	SIMPLE	Z	ALL	NULL	NULL	NULL	NULL	2	Using where
 select substr(Z.a,-1), Z.a from t1 as Y join t1 as Z on Y.a=Z.a order by 1;
 substr(Z.a,-1)	a

mysql-test/r/derived.result

@@ -57,7 +57,7 @@ a	b	a	b
 3	c	3	c
 explain select * from t1 as x1, (select * from t1) as x2;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	x1	ALL	NULL	NULL	NULL	NULL	4	
+1	PRIMARY	x1	ALL	NULL	NULL	NULL	NULL	4	Using join cache
 1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	4	
 2	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	4	
 drop table if exists  t2,t3;
@@ -188,13 +188,13 @@ pla_id	test
 105	3
 explain SELECT STRAIGHT_JOIN d.pla_id, m2.mat_id FROM t1 m2 INNER JOIN (SELECT mp.pla_id, MIN(m1.matintnum) AS matintnum FROM t2 mp INNER JOIN t1 m1 ON mp.mat_id=m1.mat_id GROUP BY mp.pla_id) d ON d.matintnum=m2.matintnum;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	m2	ALL	NULL	NULL	NULL	NULL	9	
+1	PRIMARY	m2	ALL	NULL	NULL	NULL	NULL	9	Using join cache
 1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	DERIVED	mp	ALL	NULL	NULL	NULL	NULL	9	Using temporary; Using filesort
 2	DERIVED	m1	eq_ref	PRIMARY	PRIMARY	3	test.mp.mat_id	1	
 explain SELECT STRAIGHT_JOIN d.pla_id, m2.test FROM t1 m2  INNER JOIN (SELECT mp.pla_id, MIN(m1.matintnum) AS matintnum FROM t2 mp INNER JOIN t1 m1 ON mp.mat_id=m1.mat_id GROUP BY mp.pla_id) d ON d.matintnum=m2.matintnum;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	m2	ALL	NULL	NULL	NULL	NULL	9	
+1	PRIMARY	m2	ALL	NULL	NULL	NULL	NULL	9	Using join cache
 1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	DERIVED	mp	ALL	NULL	NULL	NULL	NULL	9	Using temporary; Using filesort
 2	DERIVED	m1	eq_ref	PRIMARY	PRIMARY	3	test.mp.mat_id	1	
@@ -245,7 +245,7 @@ a	a
 2	2
 explain select * from ( select * from t1 union select * from t1) a,(select * from t1 union select * from t1) b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	2	
+1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	2	Using join cache
 1	PRIMARY	<derived4>	ALL	NULL	NULL	NULL	NULL	2	
 4	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	2	
 5	UNION	t1	ALL	NULL	NULL	NULL	NULL	2	
@@ -312,7 +312,7 @@ b	3.5000
 explain SELECT s.name, AVG(s.val) AS median FROM (SELECT x.name, x.val FROM t1 x, t1 y WHERE x.name=y.name GROUP BY x.name, x.val HAVING SUM(y.val <= x.val) >= COUNT(*)/2 AND SUM(y.val >= x.val) >= COUNT(*)/2) AS s GROUP BY s.name;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	3	Using temporary; Using filesort
-2	DERIVED	x	ALL	NULL	NULL	NULL	NULL	17	Using temporary; Using filesort
+2	DERIVED	x	ALL	NULL	NULL	NULL	NULL	17	Using temporary; Using filesort; Using join cache
 2	DERIVED	y	ALL	NULL	NULL	NULL	NULL	17	Using where
 drop table t1;
 create table t2 (a int, b int, primary key (a));

mysql-test/r/distinct.result

@@ -174,7 +174,7 @@ INSERT INTO t3 VALUES (1,'1'),(2,'2'),(1,'1'),(2,'2');
 explain SELECT distinct t3.a FROM t3,t2,t1 WHERE t3.a=t1.b AND t1.a=t2.a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	4	Using temporary
-1	SIMPLE	t3	ref	a	a	5	test.t1.b	2	Using where; Using index
+1	SIMPLE	t3	ref	a	a	5	test.t1.b	2	Using where; Using index; Using join cache
 1	SIMPLE	t2	index	a	a	4	NULL	5	Using where; Using index; Distinct
 SELECT distinct t3.a FROM t3,t2,t1 WHERE t3.a=t1.b AND t1.a=t2.a;
 a
@@ -299,11 +299,11 @@ WHERE
 ((t1.id=j_lj_t2.id AND t2_lj.id IS NULL) OR (t1.id=t2.id AND t2.idx=2))
 AND ((t1.id=j_lj_t3.id AND t3_lj.id IS NULL) OR (t1.id=t3.id AND t3.idx=2));
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	id	id	4	NULL	2	Using index; Using temporary
-1	SIMPLE	t2	index	id	id	8	NULL	1	Using index; Distinct
-1	SIMPLE	t3	index	id	id	8	NULL	1	Using index; Distinct
+1	SIMPLE	t1	index	id	id	4	NULL	2	Using index; Using temporary; Using join cache
+1	SIMPLE	t2	index	id	id	8	NULL	1	Using index; Distinct; Using join cache
+1	SIMPLE	t3	index	id	id	8	NULL	1	Using index; Distinct; Using join cache
 1	SIMPLE	j_lj_t2	index	id	id	4	NULL	2	Using where; Using index; Distinct
-1	SIMPLE	t2_lj	ref	id	id	4	test.j_lj_t2.id	1	Using where; Using index; Distinct
+1	SIMPLE	t2_lj	ref	id	id	4	test.j_lj_t2.id	1	Using where; Using index; Distinct; Using join cache
 1	SIMPLE	j_lj_t3	index	id	id	4	NULL	2	Using where; Using index; Distinct
 1	SIMPLE	t3_lj	ref	id	id	4	test.j_lj_t3.id	1	Using where; Using index; Distinct
 SELECT DISTINCT
@@ -514,7 +514,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
 EXPLAIN SELECT DISTINCT t1_1.a, t1_1.b FROM t1 t1_1, t1 t1_2;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1_1	ALL	NULL	NULL	NULL	NULL	3	Using temporary
+1	SIMPLE	t1_1	ALL	NULL	NULL	NULL	NULL	3	Using temporary; Using join cache
 1	SIMPLE	t1_2	index	NULL	PRIMARY	4	NULL	3	Using index; Distinct
 EXPLAIN SELECT DISTINCT t1_1.a, t1_1.b FROM t1 t1_1, t1 t1_2
 WHERE t1_1.a = t1_2.a;

mysql-test/r/func_group.result

@@ -613,7 +613,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 explain
 select max(t1.a3), min(t2.a2) from t1, t2 where t1.a2 = 2 and t1.a3 < 'MIN' and t2.a3 > 'CA';
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	k1	k1	7	NULL	1	Using where; Using index
+1	SIMPLE	t1	range	k1	k1	7	NULL	1	Using where; Using index; Using join cache
 1	SIMPLE	t2	range	k1	k1	3	NULL	4	Using where; Using index
 explain
 select min(a4 - 0.01) from t1;
@@ -650,7 +650,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 explain
 select concat(min(t1.a1),min(t2.a4)) from t1, t2 where t2.a4 <> 'AME';
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	range	k2	k2	4	NULL	6	Using where; Using index
+1	SIMPLE	t2	range	k2	k2	4	NULL	6	Using where; Using index; Using join cache
 1	SIMPLE	t1	index	NULL	PRIMARY	3	NULL	15	Using index
 drop table t1, t2;
 create table t1 (a char(10));

mysql-test/r/func_group_innodb.result

@@ -78,7 +78,7 @@ min(7)
 7
 explain select min(7) from t2i join t1i;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2i	ALL	NULL	NULL	NULL	NULL	1	
+1	SIMPLE	t2i	ALL	NULL	NULL	NULL	NULL	1	Using join cache
 1	SIMPLE	t1i	ALL	NULL	NULL	NULL	NULL	1	
 select min(7) from t2i join t1i;
 min(7)
@@ -94,7 +94,7 @@ max(7)
 7
 explain select max(7) from t2i join t1i;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2i	ALL	NULL	NULL	NULL	NULL	1	
+1	SIMPLE	t2i	ALL	NULL	NULL	NULL	NULL	1	Using join cache
 1	SIMPLE	t1i	ALL	NULL	NULL	NULL	NULL	1	
 select max(7) from t2i join t1i;
 max(7)

mysql-test/r/gis.result

@@ -394,7 +394,7 @@ Equals(g1.g, g2.g) as e, Disjoint(g1.g, g2.g) as d, Touches(g1.g, g2.g) as t,
 Intersects(g1.g, g2.g) as i, Crosses(g1.g, g2.g) as r
 FROM gis_geometrycollection g1, gis_geometrycollection g2 ORDER BY first, second;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	g1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using temporary; Using filesort
+1	SIMPLE	g1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using temporary; Using filesort; Using join cache
 1	SIMPLE	g2	ALL	NULL	NULL	NULL	NULL	2	100.00	
 Warnings:
 Note	1003	select `test`.`g1`.`fid` AS `first`,`test`.`g2`.`fid` AS `second`,within(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `w`,contains(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `c`,overlaps(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `o`,equals(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `e`,disjoint(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `d`,touches(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `t`,intersects(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `i`,crosses(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `r` from `test`.`gis_geometrycollection` `g1` join `test`.`gis_geometrycollection` `g2` order by `test`.`g1`.`fid`,`test`.`g2`.`fid`

mysql-test/r/group_by.result

@@ -536,11 +536,11 @@ a	b
 1	1
 explain select t1.a,t2.b from t1,t2 where t1.a=t2.a group by t1.a,t2.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	6	Using temporary; Using filesort
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	6	Using temporary; Using filesort; Using join cache
 1	SIMPLE	t2	ALL	a	NULL	NULL	NULL	4	Using where
 explain select t1.a,t2.b from t1,t2 where t1.a=t2.a group by t1.a,t2.b ORDER BY NULL;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	6	Using temporary
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	6	Using temporary; Using join cache
 1	SIMPLE	t2	ALL	a	NULL	NULL	NULL	4	Using where
 drop table t1,t2;
 create table t1 (a int, b int);

mysql-test/r/group_min_max.result

@@ -2266,7 +2266,7 @@ EXPLAIN SELECT 1 FROM t1 AS t1_outer1 JOIN t1 AS t1_outer2
 ON t1_outer1.a = (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) 
 AND t1_outer1.b = t1_outer2.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t1_outer1	ref	a	a	5	const	1	Using where; Using index
+1	PRIMARY	t1_outer1	ref	a	a	5	const	1	Using where; Using index; Using join cache
 1	PRIMARY	t1_outer2	index	NULL	a	10	NULL	15	Using where; Using index
 2	SUBQUERY	t1	range	NULL	a	5	NULL	8	Using index for group-by
 EXPLAIN SELECT (SELECT (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) x

mysql-test/r/index_merge_myisam.result

@@ -270,7 +270,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 explain select * from t0,t1 where t0.key1 = 5 and
 (t1.key1 = t0.key1 or t1.key8 = t0.key1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t0	ref	i1	i1	4	const	1	
+1	SIMPLE	t0	ref	i1	i1	4	const	1	Using join cache
 1	SIMPLE	t1	index_merge	i1,i8	i1,i8	4,4	NULL	2	Using union(i1,i8); Using where
 explain select * from t0,t1 where t0.key1 < 3 and
 (t1.key1 = t0.key1 or t1.key8 = t0.key1);
@@ -347,7 +347,7 @@ from t0 as A force index(i1,i2), t0 as B force index (i1,i2)
 where (A.key1 < 500000 or A.key2 < 3)
 and   (B.key1 < 500000 or B.key2 < 3);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	A	index_merge	i1,i2	i1,i2	4,4	NULL	1013	Using sort_union(i1,i2); Using where
+1	SIMPLE	A	index_merge	i1,i2	i1,i2	4,4	NULL	1013	Using sort_union(i1,i2); Using where; Using join cache
 1	SIMPLE	B	index_merge	i1,i2	i1,i2	4,4	NULL	1013	Using sort_union(i1,i2); Using where
 select max(A.key1 + B.key1 + A.key2 + B.key2 + A.key3 + B.key3 + A.key4 + B.key4 + A.key5 + B.key5)
 from t0 as A force index(i1,i2), t0 as B force index (i1,i2)
@@ -361,7 +361,7 @@ from t0 as A force index(i1,i2), t0 as B force index (i1,i2)
 where (A.key1 = 1 or A.key2 = 1)
 and   (B.key1 = 1 or B.key2 = 1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	A	index_merge	i1,i2	i1,i2	4,4	NULL	1020	Using union(i1,i2); Using where
+1	SIMPLE	A	index_merge	i1,i2	i1,i2	4,4	NULL	1020	Using union(i1,i2); Using where; Using join cache
 1	SIMPLE	B	index_merge	i1,i2	i1,i2	4,4	NULL	1020	Using union(i1,i2); Using where
 select max(A.key1 + B.key1 + A.key2 + B.key2 + A.key3 + B.key3 + A.key4 + B.key4 + A.key5 + B.key5)
 from t0 as A force index(i1,i2), t0 as B force index (i1,i2)
@@ -376,7 +376,7 @@ from t0 as A, t0 as B
 where (A.key1 = 1 and A.key2 = 1 and A.key3 = 1 and A.key4=1 and A.key5=1 and A.key6=1 and A.key7 = 1 or A.key8=1)
 and (B.key1 = 1 and B.key2 = 1 and B.key3 = 1 and B.key4=1 and B.key5=1 and B.key6=1 and B.key7 = 1 or B.key8=1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	A	index_merge	i1,i2,i3,i4,i5,i6,i7?,i8	i2,i3,i4,i5,i6,i7?,i8	X	NULL	#	Using union(intersect(i2,i3,i4,i5,i6,i7?),i8); Using where
+1	SIMPLE	A	index_merge	i1,i2,i3,i4,i5,i6,i7?,i8	i2,i3,i4,i5,i6,i7?,i8	X	NULL	#	Using union(intersect(i2,i3,i4,i5,i6,i7?),i8); Using where; Using join cache
 1	SIMPLE	B	index_merge	i1,i2,i3,i4,i5,i6,i7?,i8	i2,i3,i4,i5,i6,i7?,i8	X	NULL	#	Using union(intersect(i2,i3,i4,i5,i6,i7?),i8); Using where
 select max(A.key1 + B.key1 + A.key2 + B.key2 + A.key3 + B.key3 + A.key4 + B.key4 + A.key5 + B.key5)
 from t0 as A, t0 as B

mysql-test/r/information_schema.result

@@ -289,7 +289,7 @@ explain select a.ROUTINE_NAME from information_schema.ROUTINES a,
 information_schema.SCHEMATA b where
 a.ROUTINE_SCHEMA = b.SCHEMA_NAME;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	#	ALL	NULL	NULL	NULL	NULL	2	
+1	SIMPLE	#	ALL	NULL	NULL	NULL	NULL	2	Using join cache
 1	SIMPLE	#	ALL	NULL	NULL	NULL	NULL	2	Using where
 select a.ROUTINE_NAME, b.name from information_schema.ROUTINES a,
 mysql.proc b where a.ROUTINE_NAME = convert(b.name using utf8) order by 1;

mysql-test/r/innodb_gis.result

@@ -402,7 +402,7 @@ Equals(g1.g, g2.g) as e, Disjoint(g1.g, g2.g) as d, Touches(g1.g, g2.g) as t,
 Intersects(g1.g, g2.g) as i, Crosses(g1.g, g2.g) as r
 FROM gis_geometrycollection g1, gis_geometrycollection g2 ORDER BY first, second;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	g1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using temporary; Using filesort
+1	SIMPLE	g1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using temporary; Using filesort; Using join cache
 1	SIMPLE	g2	ALL	NULL	NULL	NULL	NULL	2	100.00	
 Warnings:
 Note	1003	select `test`.`g1`.`fid` AS `first`,`test`.`g2`.`fid` AS `second`,within(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `w`,contains(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `c`,overlaps(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `o`,equals(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `e`,disjoint(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `d`,touches(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `t`,intersects(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `i`,crosses(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `r` from `test`.`gis_geometrycollection` `g1` join `test`.`gis_geometrycollection` `g2` order by `test`.`g1`.`fid`,`test`.`g2`.`fid`

mysql-test/r/innodb_mysql.result

@@ -163,7 +163,7 @@ min(7)
 7
 explain select min(7) from t2i join t1i;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2i	ALL	NULL	NULL	NULL	NULL	1	
+1	SIMPLE	t2i	ALL	NULL	NULL	NULL	NULL	1	Using join cache
 1	SIMPLE	t1i	ALL	NULL	NULL	NULL	NULL	1	
 select min(7) from t2i join t1i;
 min(7)
@@ -179,7 +179,7 @@ max(7)
 7
 explain select max(7) from t2i join t1i;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2i	ALL	NULL	NULL	NULL	NULL	1	
+1	SIMPLE	t2i	ALL	NULL	NULL	NULL	NULL	1	Using join cache
 1	SIMPLE	t1i	ALL	NULL	NULL	NULL	NULL	1	
 select max(7) from t2i join t1i;
 max(7)

mysql-test/r/join.result

@@ -403,7 +403,7 @@ EXPLAIN
 SELECT STRAIGHT_JOIN t2.e FROM t1,t2 WHERE t2.d=1 AND t1.b=t2.e
 ORDER BY t1.b, t1.c;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	32	Using temporary; Using filesort
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	32	Using temporary; Using filesort; Using join cache
 1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	16	Using where
 SELECT STRAIGHT_JOIN t2.e FROM t1,t2 WHERE t2.d=1 AND t1.b=t2.e
 ORDER BY t1.b, t1.c;

mysql-test/r/key_diff.result

@@ -35,7 +35,7 @@ D	E	a	a
 a	a	a	a
 explain select t1.*,t2.* from t1,t1 as t2 where t1.A=t2.B;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	a	NULL	NULL	NULL	5	
+1	SIMPLE	t1	ALL	a	NULL	NULL	NULL	5	Using join cache
 1	SIMPLE	t2	ALL	b	NULL	NULL	NULL	5	Using where
 select t1.*,t2.* from t1,t1 as t2 where t1.A=t2.B order by binary t1.a,t2.a;
 a	b	a	b

mysql-test/r/myisam.result

@@ -345,11 +345,11 @@ t1	1	c_2	1	c	A	5	NULL	NULL	YES	BTREE
 t1	1	c_2	2	a	A	5	NULL	NULL		BTREE	
 explain select * from t1,t2 where t1.a=t2.a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	ALL	a	NULL	NULL	NULL	2	
+1	SIMPLE	t2	ALL	a	NULL	NULL	NULL	2	Using join cache
 1	SIMPLE	t1	ALL	a	NULL	NULL	NULL	5	Using where
 explain select * from t1,t2 force index(a) where t1.a=t2.a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	ALL	a	NULL	NULL	NULL	2	
+1	SIMPLE	t2	ALL	a	NULL	NULL	NULL	2	Using join cache
 1	SIMPLE	t1	ALL	a	NULL	NULL	NULL	5	Using where
 explain select * from t1 force index(a),t2 force index(a) where t1.a=t2.a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -361,7 +361,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ref	b	b	5	test.t2.b	1	Using where
 explain select * from t1,t2 force index(c) where t1.a=t2.a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	2	
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	2	Using join cache
 1	SIMPLE	t1	ALL	a	NULL	NULL	NULL	5	Using where
 explain select * from t1 where a=0 or a=2;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

mysql-test/r/ndb_condition_pushdown.result

@@ -1730,7 +1730,7 @@ pk1	attr1	attr2	attr3	attr4
 explain
 select * from t2,t3 where t2.attr1 < 1 and t2.attr2 = t3.attr2 and t3.attr1 < 5 order by t2.pk1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	#	Using where with pushed condition; Using temporary; Using filesort
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	#	Using where with pushed condition; Using temporary; Using filesort; Using join cache
 1	SIMPLE	t3	ALL	NULL	NULL	NULL	NULL	#	Using where with pushed condition
 select * from t2,t3 where t2.attr1 < 1 and t2.attr2 = t3.attr2 and t3.attr1 < 5 order by t2.pk1;
 pk1	attr1	attr2	attr3	pk1	attr1	attr2	attr3	attr4
@@ -1746,7 +1746,7 @@ pk1	attr1	attr2	attr3	attr4
 explain
 select * from t3,t4 where t4.attr1 > 1 and t4.attr2 = t3.attr2 and t4.attr3 < 5 order by t4.pk1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t4	range	attr1	attr1	4	NULL	#	Using where with pushed condition; Using temporary; Using filesort
+1	SIMPLE	t4	range	attr1	attr1	4	NULL	#	Using where with pushed condition; Using temporary; Using filesort; Using join cache
 1	SIMPLE	t3	ALL	NULL	NULL	NULL	NULL	#	Using where
 select * from t3,t4 where t4.attr1 > 1 and t4.attr2 = t3.attr2 and t4.attr3 < 5 order by t4.pk1;
 pk1	attr1	attr2	attr3	attr4	pk1	attr1	attr2	attr3	attr4

mysql-test/r/ndb_gis.result

@@ -402,7 +402,7 @@ Equals(g1.g, g2.g) as e, Disjoint(g1.g, g2.g) as d, Touches(g1.g, g2.g) as t,
 Intersects(g1.g, g2.g) as i, Crosses(g1.g, g2.g) as r
 FROM gis_geometrycollection g1, gis_geometrycollection g2 ORDER BY first, second;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	g1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using temporary; Using filesort
+1	SIMPLE	g1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using temporary; Using filesort; Using join cache
 1	SIMPLE	g2	ALL	NULL	NULL	NULL	NULL	2	100.00	
 Warnings:
 Note	1003	select `test`.`g1`.`fid` AS `first`,`test`.`g2`.`fid` AS `second`,within(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `w`,contains(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `c`,overlaps(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `o`,equals(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `e`,disjoint(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `d`,touches(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `t`,intersects(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `i`,crosses(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `r` from `test`.`gis_geometrycollection` `g1` join `test`.`gis_geometrycollection` `g2` order by `test`.`g1`.`fid`,`test`.`g2`.`fid`
@@ -952,7 +952,7 @@ Equals(g1.g, g2.g) as e, Disjoint(g1.g, g2.g) as d, Touches(g1.g, g2.g) as t,
 Intersects(g1.g, g2.g) as i, Crosses(g1.g, g2.g) as r
 FROM gis_geometrycollection g1, gis_geometrycollection g2 ORDER BY first, second;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	g1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using temporary; Using filesort
+1	SIMPLE	g1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using temporary; Using filesort; Using join cache
 1	SIMPLE	g2	ALL	NULL	NULL	NULL	NULL	2	100.00	
 Warnings:
 Note	1003	select `test`.`g1`.`fid` AS `first`,`test`.`g2`.`fid` AS `second`,within(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `w`,contains(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `c`,overlaps(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `o`,equals(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `e`,disjoint(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `d`,touches(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `t`,intersects(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `i`,crosses(`test`.`g1`.`g`,`test`.`g2`.`g`) AS `r` from `test`.`gis_geometrycollection` `g1` join `test`.`gis_geometrycollection` `g2` order by `test`.`g1`.`fid`,`test`.`g2`.`fid`

mysql-test/r/range.result

@@ -220,27 +220,27 @@ insert into t1 (x) values (1),(2),(3),(4),(5),(6),(7),(8),(9);
 update t1 set y=x;
 explain select * from t1, t1 t2 where t1.y = 8 and t2.x between 7 and t1.y+0;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	y	y	5	const	1	Using where
+1	SIMPLE	t1	ref	y	y	5	const	1	Using where; Using join cache
 1	SIMPLE	t2	range	x	x	5	NULL	2	Using where
 explain select * from t1, t1 t2 where t1.y = 8 and t2.x >= 7 and t2.x <= t1.y+0;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	y	y	5	const	1	Using where
+1	SIMPLE	t1	ref	y	y	5	const	1	Using where; Using join cache
 1	SIMPLE	t2	range	x	x	5	NULL	2	Using where
 explain select * from t1, t1 t2 where t1.y = 2 and t2.x between t1.y-1 and t1.y+1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	y	y	5	const	1	Using where
+1	SIMPLE	t1	ref	y	y	5	const	1	Using where; Using join cache
 1	SIMPLE	t2	range	x	x	5	NULL	3	Using where
 explain select * from t1, t1 t2 where t1.y = 2 and t2.x >= t1.y-1 and t2.x <= t1.y+1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	y	y	5	const	1	Using where
+1	SIMPLE	t1	ref	y	y	5	const	1	Using where; Using join cache
 1	SIMPLE	t2	range	x	x	5	NULL	3	Using where
 explain select * from t1, t1 t2 where t1.y = 2 and t2.x between 0 and t1.y;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	y	y	5	const	1	Using where
+1	SIMPLE	t1	ref	y	y	5	const	1	Using where; Using join cache
 1	SIMPLE	t2	range	x	x	5	NULL	2	Using where
 explain select * from t1, t1 t2 where t1.y = 2 and t2.x >= 0 and t2.x <= t1.y;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	y	y	5	const	1	Using where
+1	SIMPLE	t1	ref	y	y	5	const	1	Using where; Using join cache
 1	SIMPLE	t2	range	x	x	5	NULL	2	Using where
 explain select count(*) from t1 where x in (1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -255,12 +255,12 @@ CREATE TABLE t2 (keya int(11) NOT NULL default '0', KEY j1 (keya));
 INSERT INTO t2 VALUES (0),(0),(1),(1),(2),(2);
 explain select * from t1, t2 where (t1.key1 <t2.keya + 1) and t2.keya=3;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	ref	j1	j1	4	const	1	Using index
+1	SIMPLE	t2	ref	j1	j1	4	const	1	Using index; Using join cache
 1	SIMPLE	t1	index	i1	i1	4	NULL	7	Using where; Using index
 explain select * from t1 force index(i1), t2 force index(j1) where 
 (t1.key1 <t2.keya + 1) and t2.keya=3;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	ref	j1	j1	4	const	1	Using index
+1	SIMPLE	t2	ref	j1	j1	4	const	1	Using index; Using join cache
 1	SIMPLE	t1	index	i1	i1	4	NULL	7	Using where; Using index
 DROP TABLE t1,t2;
 CREATE TABLE t1 (

mysql-test/r/row.result

@@ -376,7 +376,7 @@ a	b	a	b	c
 3	2	3	1	3
 EXPLAIN EXTENDED SELECT * FROM t1,t2 WHERE (t1.a-1,t1.b)=(t2.a-1,t2.b+1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	SIMPLE	t1	index	NULL	PRIMARY	8	NULL	6	100.00	Using index
+1	SIMPLE	t1	index	NULL	PRIMARY	8	NULL	6	100.00	Using index; Using join cache
 1	SIMPLE	t2	index	NULL	PRIMARY	12	NULL	7	100.00	Using where; Using index
 Warnings:
 Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t1` join `test`.`t2` where (((`test`.`t1`.`a` - 1) = (`test`.`t2`.`a` - 1)) and (`test`.`t1`.`b` = (`test`.`t2`.`b` + 1)))

mysql-test/r/select.result

@@ -607,11 +607,11 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t3	ref	period	period	4	test.t1.period	4181	
 explain select * from t3 as t1,t3 where t1.period=t3.period order by t3.period limit 10;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t3	index	period	period	4	NULL	41810	
+1	SIMPLE	t3	ALL	period	NULL	NULL	NULL	41810	Using filesort
 1	SIMPLE	t1	ref	period	period	4	test.t3.period	4181	
 explain select * from t3 as t1,t3 where t1.period=t3.period order by t1.period limit 10;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	period	period	4	NULL	41810	
+1	SIMPLE	t1	ALL	period	NULL	NULL	NULL	41810	Using filesort
 1	SIMPLE	t3	ref	period	period	4	test.t1.period	4181	
 select period from t1;
 period
@@ -1430,7 +1430,7 @@ companynr	companynr
 41	40
 explain select distinct t2.companynr,t4.companynr from t2,t4 where t2.companynr=t4.companynr+1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t4	index	NULL	PRIMARY	1	NULL	12	Using index; Using temporary
+1	SIMPLE	t4	index	NULL	PRIMARY	1	NULL	12	Using index; Using temporary; Using join cache
 1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	1199	Using where
 select t2.fld1,t2.companynr,fld3,period from t3,t2 where t2.fld1 = 38208 and t2.fld1=t3.t2nr and period = 1008 or t2.fld1 = 38008 and t2.fld1 =t3.t2nr and period = 1008;
 fld1	companynr	fld3	period
@@ -2362,7 +2362,7 @@ insert into t1 values (1,2), (2,2), (3,2), (4,2);
 insert into t2 values (1,3), (2,3), (3,4), (4,4);
 explain select * from t1 left join t2 on a=c where d in (4);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	ref	c,d	d	5	const	2	Using where
+1	SIMPLE	t2	ref	c,d	d	5	const	2	Using where; Using join cache
 1	SIMPLE	t1	ALL	a	NULL	NULL	NULL	4	Using where
 select * from t1 left join t2 on a=c where d in (4);
 a	b	c	d
@@ -2370,7 +2370,7 @@ a	b	c	d
 4	2	4	4
 explain select * from t1 left join t2 on a=c where d = 4;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	ref	c,d	d	5	const	2	Using where
+1	SIMPLE	t2	ref	c,d	d	5	const	2	Using where; Using join cache
 1	SIMPLE	t1	ALL	a	NULL	NULL	NULL	4	Using where
 select * from t1 left join t2 on a=c where d = 4;
 a	b	c	d
@@ -2716,7 +2716,7 @@ explain select straight_join DISTINCT t2.a,t2.b, t1.c from t1, t3, t2
 where (t1.c=t2.a or (t1.c=t3.a and t2.a=t3.b)) and t1.b=556476786 and 
 t2.b like '%%' order by t2.b limit 0,1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	b,c	b	5	const	1	Using where; Using temporary; Using filesort
+1	SIMPLE	t1	ref	b,c	b	5	const	1	Using where; Using temporary; Using filesort; Using join cache
 1	SIMPLE	t3	index	PRIMARY,a,b	PRIMARY	8	NULL	2	Using index
 1	SIMPLE	t2	ALL	PRIMARY	NULL	NULL	NULL	2	Range checked for each record (index map: 0x1)
 DROP TABLE t1,t2,t3;
@@ -2737,7 +2737,7 @@ INSERT INTO t2 VALUES (1,NULL), (2,10);
 ALTER TABLE t1 ENABLE KEYS;
 EXPLAIN SELECT STRAIGHT_JOIN SQL_NO_CACHE COUNT(*) FROM t2, t1 WHERE t1.b = t2.b OR t2.b IS NULL;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	index	b	b	5	NULL	2	Using index
+1	SIMPLE	t2	index	b	b	5	NULL	2	Using index; Using join cache
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 SELECT STRAIGHT_JOIN SQL_NO_CACHE * FROM t2, t1 WHERE t1.b = t2.b OR t2.b IS NULL;
 a	b	a	b
@@ -2747,7 +2747,7 @@ a	b	a	b
 2	10	4	10
 EXPLAIN SELECT STRAIGHT_JOIN SQL_NO_CACHE COUNT(*) FROM t2, t1 WHERE t1.b = t2.b OR t2.b IS NULL;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	index	b	b	5	NULL	2	Using index
+1	SIMPLE	t2	index	b	b	5	NULL	2	Using index; Using join cache
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 SELECT STRAIGHT_JOIN SQL_NO_CACHE * FROM t2, t1 WHERE t1.b = t2.b OR t2.b IS NULL;
 a	b	a	b
@@ -2901,11 +2901,11 @@ a
 4
 EXPLAIN SELECT t1.a FROM t1 STRAIGHT_JOIN t2 ON t1.a=t2.a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	5	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	5	Using join cache
 1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	Using where
 EXPLAIN SELECT t1.a FROM t1 INNER JOIN t2 ON t1.a=t2.a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	Using join cache
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	5	Using where
 DROP TABLE t1,t2;
 select x'10' + 0, X'10' + 0, b'10' + 0, B'10' + 0;

mysql-test/r/ssl.result

@@ -608,11 +608,11 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t3	ref	period	period	4	test.t1.period	4181	
 explain select * from t3 as t1,t3 where t1.period=t3.period order by t3.period limit 10;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t3	index	period	period	4	NULL	41810	
+1	SIMPLE	t3	ALL	period	NULL	NULL	NULL	41810	Using filesort
 1	SIMPLE	t1	ref	period	period	4	test.t3.period	4181	
 explain select * from t3 as t1,t3 where t1.period=t3.period order by t1.period limit 10;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	period	period	4	NULL	41810	
+1	SIMPLE	t1	ALL	period	NULL	NULL	NULL	41810	Using filesort
 1	SIMPLE	t3	ref	period	period	4	test.t1.period	4181	
 select period from t1;
 period
@@ -1431,7 +1431,7 @@ companynr	companynr
 41	40
 explain select distinct t2.companynr,t4.companynr from t2,t4 where t2.companynr=t4.companynr+1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t4	index	NULL	PRIMARY	1	NULL	12	Using index; Using temporary
+1	SIMPLE	t4	index	NULL	PRIMARY	1	NULL	12	Using index; Using temporary; Using join cache
 1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	1199	Using where
 select t2.fld1,t2.companynr,fld3,period from t3,t2 where t2.fld1 = 38208 and t2.fld1=t3.t2nr and period = 1008 or t2.fld1 = 38008 and t2.fld1 =t3.t2nr and period = 1008;
 fld1	companynr	fld3	period

mysql-test/r/ssl_compress.result

@@ -611,11 +611,11 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t3	ref	period	period	4	test.t1.period	4181	
 explain select * from t3 as t1,t3 where t1.period=t3.period order by t3.period limit 10;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t3	index	period	period	4	NULL	41810	
+1	SIMPLE	t3	ALL	period	NULL	NULL	NULL	41810	Using filesort
 1	SIMPLE	t1	ref	period	period	4	test.t3.period	4181	
 explain select * from t3 as t1,t3 where t1.period=t3.period order by t1.period limit 10;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	period	period	4	NULL	41810	
+1	SIMPLE	t1	ALL	period	NULL	NULL	NULL	41810	Using filesort
 1	SIMPLE	t3	ref	period	period	4	test.t1.period	4181	
 select period from t1;
 period
@@ -1434,7 +1434,7 @@ companynr	companynr
 41	40
 explain select distinct t2.companynr,t4.companynr from t2,t4 where t2.companynr=t4.companynr+1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t4	index	NULL	PRIMARY	1	NULL	12	Using index; Using temporary
+1	SIMPLE	t4	index	NULL	PRIMARY	1	NULL	12	Using index; Using temporary; Using join cache
 1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	1199	Using where
 select t2.fld1,t2.companynr,fld3,period from t3,t2 where t2.fld1 = 38208 and t2.fld1=t3.t2nr and period = 1008 or t2.fld1 = 38008 and t2.fld1 =t3.t2nr and period = 1008;
 fld1	companynr	fld3	period

mysql-test/r/subselect.result

@@ -904,7 +904,7 @@ a	t1.a in (select t2.a from t2,t3 where t3.a=t2.a)
 explain extended 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	filtered	Extra
 1	PRIMARY	t1	index	NULL	PRIMARY	4	NULL	4	100.00	Using index
-2	DEPENDENT SUBQUERY	t2	ref_or_null	a	a	5	func	2	100.00	Using where; Using index
+2	DEPENDENT SUBQUERY	t2	ref_or_null	a	a	5	func	2	100.00	Using where; Using index; Using join cache
 2	DEPENDENT SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
 Warnings:
 Note	1003	select `test`.`t1`.`a` AS `a`,<in_optimizer>(`test`.`t1`.`a`,<exists>(select 1 AS `Not_used` from `test`.`t2` join `test`.`t3` where ((`test`.`t3`.`a` = `test`.`t2`.`a`) and ((<cache>(`test`.`t1`.`a`) = `test`.`t2`.`a`) or isnull(`test`.`t2`.`a`))) having <is_not_null_test>(`test`.`t2`.`a`))) AS `t1.a in (select t2.a from t2,t3 where t3.a=t2.a)` from `test`.`t1`
@@ -1354,7 +1354,7 @@ a
 explain extended 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	filtered	Extra
 1	PRIMARY	t2	index	NULL	a	5	NULL	4	100.00	Using where; Using index
-2	DEPENDENT SUBQUERY	t1	ref	a	a	5	func	1001	100.00	Using where; Using index
+2	DEPENDENT SUBQUERY	t1	ref	a	a	5	func	1001	100.00	Using where; Using index; Using join cache
 2	DEPENDENT SUBQUERY	t3	index	a	a	5	NULL	3	100.00	Using where; Using index
 Warnings:
 Note	1003	select `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(select 1 AS `Not_used` from `test`.`t1` join `test`.`t3` where ((`test`.`t3`.`a` = `test`.`t1`.`b`) and (<cache>(`test`.`t2`.`a`) = `test`.`t1`.`a`))))

mysql-test/r/subselect3.result

@@ -254,7 +254,7 @@ select a,b, oref,
 from t2;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	
-2	DEPENDENT SUBQUERY	t1	ref_or_null	a	a	5	func	2	100.00	Using where; Full scan on NULL key
+2	DEPENDENT SUBQUERY	t1	ref_or_null	a	a	5	func	2	100.00	Using where; Full scan on NULL key; Using join cache
 2	DEPENDENT SUBQUERY	t4	ALL	NULL	NULL	NULL	NULL	100	100.00	Using where
 Warnings:
 Note	1276	Field or reference 'test.t2.oref' of SELECT #2 was resolved in SELECT #1

mysql-test/r/union.result

@@ -499,7 +499,7 @@ a	b
 explain (select * from t1 where a=1 and b=10) union (select straight_join t1.a,t2.a from t1,t2 where t1.a=t2.a);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables
-2	UNION	t1	index	PRIMARY	PRIMARY	4	NULL	4	Using index
+2	UNION	t1	index	PRIMARY	PRIMARY	4	NULL	4	Using index; Using join cache
 2	UNION	t2	index	PRIMARY	PRIMARY	4	NULL	4	Using where; Using index
 NULL	UNION RESULT	<union1,2>	ALL	NULL	NULL	NULL	NULL	NULL	
 explain (select * from t1 where a=1) union (select * from t1 where b=1);

mysql-test/r/view.result

@@ -2317,7 +2317,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t2	ref	a	a	10	const,test.t1.b	2	Using where; Using index
 EXPLAIN SELECT * FROM v2 WHERE a=1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	a	a	5	const	1	Using where; Using index
+1	SIMPLE	t1	ref	a	a	5	const	1	Using where; Using index; Using join cache
 1	SIMPLE	t3	ALL	NULL	NULL	NULL	NULL	3	Using where
 DROP VIEW v1,v2;
 DROP TABLE t1,t2,t3;

sql/sql_select.cc

@@ -5893,6 +5893,12 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
         tab->ref.key= -1;
 	tab->ref.key_parts=0;		// Don't use ref key.
 	join->best_positions[i].records_read= rows2double(tab->quick->records);
+        /* 
+          We will use join cache here : prevent sorting of the first
+          table only and sort at the end.
+        */
+        if (i != join->const_tables && join->tables > join->const_tables + 1)
+          join->full_join= 1;
       }
 
       tmp= NULL;
@@ -12660,6 +12666,12 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
     uint nr;
     key_map keys;
 
+    /* 
+      filesort() and join cache are usually faster than reading in 
+      index order and not using join cache
+    */
+    if (tab->type == JT_ALL && tab->join->tables > tab->join->const_tables + 1)
+      DBUG_RETURN(0);
     /*
       If not used with LIMIT, only use keys if the whole query can be
       resolved with a key;  This is because filesort() is usually faster than
@@ -15513,6 +15525,8 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
             break;
           }
         }
+        if (tab->next_select == sub_select_cache)
+          extra.append(STRING_WITH_LEN("; Using join cache"));
         
         /* Skip initial "; "*/
         const char *str= extra.ptr();