Fixed bug #52636.

Applied the fix for bug #47217 from the mysql-6.0 codebase.
The patch adds not null predicates generated for the left parts
of the equality predicates used for ref accesses. This is done
for such predicates both in where conditions and on conditions.
For the where conditions the not null predicates were generated
but in 5.0/5.1 they actually never were used due to some lame
merge from 4.1 to 5.0. The fix for bug #47217 made these 
predicates to be used in the condition pushed to the tables.
Yet only this patch generates not null predicates for equality
predicated from on conditions of outer joins.
This patch introduces a performance regression that can be
observed on a test case from null_key.test. The regression
will disappear after the fix for bug #57024 from mariadb-5.1
is pulled into mariadb-5.3.
The patch contains many changes in the outputs of the EXPLAIN 
commands since generated not null predicates are considered as
parts of the conditions pushed to join tables and may add
'Usingwhere' in some rows of EXPLAINs where there used
to be no such comments.

mysql-test/r/distinct.result

@@ -173,7 +173,7 @@ INSERT INTO t2 values (1),(2),(3);
 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	t1	ALL	PRIMARY	NULL	NULL	NULL	4	Using where; Using temporary
 1	SIMPLE	t3	ref	a	a	5	test.t1.b	2	Using index
 1	SIMPLE	t2	index	a	a	4	NULL	5	Using where; Using index; Distinct; Using join buffer
 SELECT distinct t3.a FROM t3,t2,t1 WHERE t3.a=t1.b AND t1.a=t2.a;

mysql-test/r/group_by.result

@@ -873,7 +873,7 @@ explain
 SELECT straight_join sql_no_cache v1.a, v1.b, v1.real_b from t2, v1
 where t2.b=v1.a GROUP BY t2.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	index	b	b	2	NULL	10	Using index
+1	SIMPLE	t2	index	b	b	2	NULL	10	Using where; Using index
 1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	1	test.t2.b	1	
 SELECT straight_join sql_no_cache v1.a, v1.b, v1.real_b from t2, v1
 where t2.b=v1.a GROUP BY t2.b;

mysql-test/r/join.result

@@ -846,7 +846,7 @@ select * from t1, t2, t3 where t3.a=t1.a and t2.a=t1.b;
 a	b	a	a
 explain select * from t1, t2, t3 where t3.a=t1.a and t2.a=t1.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
 1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.b	1	Using index
 1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using index
 We expect rnd_next=5, and read_key must be 0 because of short-cutting:
@@ -889,8 +889,8 @@ Z
 vv: Following query must use ALL(t1), eq_ref(A), eq_ref(B): vv
 explain select * from t1, t2 A, t2 B where A.a = t1.a and B.a=A.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	10	
-1	SIMPLE	A	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	10	Using where
+1	SIMPLE	A	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where
 1	SIMPLE	B	eq_ref	PRIMARY	PRIMARY	4	test.A.b	1	
 show status like '%cost%';
 Variable_name	Value
@@ -910,7 +910,7 @@ INSERT INTO t1 SELECT a + 64, b FROM t1;
 INSERT INTO t2 SELECT a, b FROM t1;
 EXPLAIN SELECT * FROM t1 JOIN t2 ON b=c ORDER BY a LIMIT 2;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	2	
+1	SIMPLE	t1	index	NULL	PRIMARY	4	NULL	2	Using where
 1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.b	1	
 EXPLAIN SELECT * FROM t1 JOIN t2 ON a=c ORDER BY a LIMIT 2;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -924,7 +924,7 @@ a	b	c	d
 2	NULL	2	NULL
 EXPLAIN SELECT * FROM t1 JOIN t2 ON b=c ORDER BY a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	128	Using filesort
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	128	Using where; Using filesort
 1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.b	1	
 EXPLAIN SELECT * FROM t1 JOIN t2 ON a=c ORDER BY a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -1095,7 +1095,7 @@ ON t4.a = t5.a
 ON t1.a = t3.a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
-1	SIMPLE	t3	ref	a	a	5	test.t1.a	2	Using index
+1	SIMPLE	t3	ref	a	a	5	test.t1.a	2	Using where; Using index
 1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	0	Using where
 1	SIMPLE	t5	ALL	NULL	NULL	NULL	NULL	0	Using where
 1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	0	Using where
@@ -1184,4 +1184,34 @@ NULL
 NULL
 1
 DROP TABLE t1, t2, mm1;
+#
+# BUG#47217 Lost optimization caused slowdown & wrong result.
+#
+CREATE TABLE t1 (pk INT, v VARCHAR(2), PRIMARY KEY(pk));
+CREATE INDEX ix1 ON t1(v);
+CREATE TABLE t2 (pk INT, v VARCHAR(2), PRIMARY KEY(pk));
+CREATE INDEX ix2 ON t2(v);
+INSERT INTO t1 VALUES (1,'a'),(2,NULL);
+INSERT INTO t2 VALUES (1,NULL);
+EXPLAIN SELECT * FROM t1 JOIN t2 ON t1.v = t2.v ORDER BY 1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables
+EXPLAIN SELECT * FROM t1 JOIN t2 ON t1.v = t2.v;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables
+INSERT INTO t1 VALUES (3,'b'),(4,NULL),(5,'c'),(6,'cc'),(7,'d'),
+(8,'dd'),(9,'e'),(10,'ee');
+INSERT INTO t2 VALUES (2,NULL);
+FLUSH STATUS;
+SELECT * FROM t1 JOIN t2 ON t1.v = t2.v WHERE t2.v IS NULL ORDER BY 1;
+pk	v	pk	v
+SHOW STATUS LIKE 'Handler_read_%';
+Variable_name	Value
+Handler_read_first	0
+Handler_read_key	1
+Handler_read_next	0
+Handler_read_prev	0
+Handler_read_rnd	0
+Handler_read_rnd_next	1
+DROP TABLE t1, t2;
 End of 5.1 tests

mysql-test/r/join_cache.result

@@ -4379,7 +4379,7 @@ SELECT a1<>a2, a1, a2, b2, b3, c3,
 SUBSTR(filler1,1,1) AS s1, SUBSTR(filler2,1,1) AS s2
 FROM t1,t2,t3 WHERE a1=a2 AND b2=b3 AND MOD(c3,10)>7;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	9	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	9	Using where
 1	SIMPLE	t2	ref	PRIMARY	PRIMARY	4	test.t1.a1	1	Using index
 1	SIMPLE	t3	ref	idx	idx	5	test.t2.b2	5	Using where
 SELECT a1<>a2, a1, a2, b2, b3, c3,
@@ -4407,7 +4407,7 @@ SELECT a1<>a2, a1, a2, b2, b3, c3,
 SUBSTR(filler1,1,1) AS s1, SUBSTR(filler2,1,1) AS s2
 FROM t1,t2,t3 WHERE a1=a2 AND b2=b3 AND MOD(c3,10)>7;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	9	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	9	Using where
 1	SIMPLE	t2	ref	PRIMARY	PRIMARY	4	test.t1.a1	1	Using index
 1	SIMPLE	t3	ref	idx	idx	5	test.t2.b2	5	Using where; Using join buffer
 SELECT a1<>a2, a1, a2, b2, b3, c3,
@@ -4619,7 +4619,7 @@ set join_cache_level=6;
 set join_buffer_size=1024;
 EXPLAIN SELECT AVG(c) FROM t1,t2 WHERE 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	2050	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2050	Using where
 1	SIMPLE	t2	ref	idx	idx	5	test.t1.a	640	Using join buffer
 SELECT AVG(c) FROM t1,t2 WHERE t1.a=t2.b;
 AVG(c)
@@ -4796,7 +4796,7 @@ f1	f2	f3
 explain select t2.f1, t2.f2, t2.f3 from t1,t2
 where t1.f1=t2.f1 and t2.f2 between t1.f1 and t2.f2;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 1	SIMPLE	t2	ref	f1	f1	4	test.t1.f1	3	Using index condition(BKA); Using join buffer
 set join_cache_level=6;
 select t2.f1, t2.f2, t2.f3 from t1,t2
@@ -4809,7 +4809,7 @@ f1	f2	f3
 explain select t2.f1, t2.f2, t2.f3 from t1,t2
 where t1.f1=t2.f1 and t2.f2 between t1.f1 and t2.f2;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 1	SIMPLE	t2	ref	f1	f1	4	test.t1.f1	3	Using index condition(BKA); Using join buffer
 set join_cache_level=7;
 select t2.f1, t2.f2, t2.f3 from t1,t2
@@ -4822,7 +4822,7 @@ f1	f2	f3
 explain select t2.f1, t2.f2, t2.f3 from t1,t2
 where t1.f1=t2.f1 and t2.f2 between t1.f1 and t2.f2;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 1	SIMPLE	t2	ref	f1	f1	4	test.t1.f1	3	Using index condition(BKA); Using join buffer
 set join_cache_level=8;
 select t2.f1, t2.f2, t2.f3 from t1,t2
@@ -4835,7 +4835,7 @@ f1	f2	f3
 explain select t2.f1, t2.f2, t2.f3 from t1,t2
 where t1.f1=t2.f1 and t2.f2 between t1.f1 and t2.f2;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 1	SIMPLE	t2	ref	f1	f1	4	test.t1.f1	3	Using index condition(BKA); Using join buffer
 drop table t1,t2;
 set join_cache_level=default;
@@ -4854,7 +4854,7 @@ explain
 select t1.id1, sum(t2.id2) from t1 join t2 on t1.id1=t2.id1 
 where t1.d=3 group by t1.id1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	idx1	idx1	5	const	4	Using index; Using temporary; Using filesort
+1	SIMPLE	t1	ref	idx1	idx1	5	const	4	Using where; Using index; Using temporary; Using filesort
 1	SIMPLE	t2	ref	idx2	idx2	5	test.t1.id1	2	Using join buffer
 select t1.id1, sum(t2.id2) from t1 join t2 on t1.id1=t2.id1 
 where t1.d=3 group by t1.id1;
@@ -4866,7 +4866,7 @@ explain
 select t1.id1  from t1 join t2 on t1.id1=t2.id1 
 where t1.d=3 and t2.id2 > 200 order by t1.id1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	idx1	idx1	5	const	4	Using index; Using temporary; Using filesort
+1	SIMPLE	t1	ref	idx1	idx1	5	const	4	Using where; Using index; Using temporary; Using filesort
 1	SIMPLE	t2	ref	idx2	idx2	5	test.t1.id1	2	Using where; Using join buffer
 select t1.id1  from t1 join t2 on t1.id1=t2.id1 
 where t1.d=3 and t2.id2 > 200 order by t1.id1;
@@ -4910,7 +4910,7 @@ explain
 select t1.a, t1.b, t1.c, t1.d, t2.e, t3.f, t4.g from t1,t2,t3,t4
 where t2.b=t1.b and t3.d=t1.d and t4.c=t1.c;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	7	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	7	Using where
 1	SIMPLE	t2	ref	idx	idx	5	test.t1.b	1	
 1	SIMPLE	t3	ref	idx	idx	5	test.t1.d	1	
 1	SIMPLE	t4	ref	idx	idx	5	test.t1.c	1	
@@ -4923,7 +4923,7 @@ explain
 select t1.a, t1.b, t1.c, t1.d, t2.e, t3.f, t4.g from t1,t2,t3,t4
 where t2.b=t1.b and t3.d=t1.d and t4.c=t1.c;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	7	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	7	Using where
 1	SIMPLE	t2	ref	idx	idx	5	test.t1.b	1	Using join buffer
 1	SIMPLE	t3	ref	idx	idx	5	test.t1.d	1	Using join buffer
 1	SIMPLE	t4	ref	idx	idx	5	test.t1.c	1	Using join buffer
@@ -4974,8 +4974,8 @@ FROM t1 JOIN  t2 JOIN  t3 JOIN  t4 JOIN  t5
 WHERE t1.id1=t5.id1 AND t1.id2=t5.id2 and  t4.id2=t1.id2 AND
 t5.enum2='Active' AND t3.id4=t2.id4 AND t2.id3=t1.id3 AND t3.text1<'D';
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	349	
-1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	8	test.t1.id3	1	Using join buffer
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	349	Using where
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	8	test.t1.id3	1	Using where; Using join buffer
 1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	8	test.t2.id4	1	Using where; Using join buffer
 1	SIMPLE	t4	eq_ref	PRIMARY	PRIMARY	8	test.t1.id2	1	Using join buffer
 1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	16	test.t1.id1,test.t1.id2	1	Using where; Using join buffer
@@ -5189,7 +5189,7 @@ INSERT INTO t3 VALUES
 EXPLAIN
 SELECT t3.a FROM t1,t2,t3 WHERE t1.a = t3.a AND t1.b = t3.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	Using where
 1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	5	Using join buffer
 1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where; Using join buffer
 SELECT t3.a FROM t1,t2,t3 WHERE t1.a = t3.a AND t1.b = t3.b;
@@ -5238,8 +5238,69 @@ ON t3.carrier = t1.carrier;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	2	
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	Using join buffer
-1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.carrier	1	
+1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.carrier	1	Using where
 1	SIMPLE	t4	ref	carrier_id	carrier_id	5	test.t3.id	2	Using index
 SET join_cache_level=default;
 DROP TABLE t1,t2,t3,t4;
+#
+# BUG#52636: allowing JOINs on NULL values w/ join_cache_level = 5-8
+#
+CREATE TABLE t1 (b int);
+INSERT INTO t1 VALUES (NULL),(3);
+CREATE TABLE t2 (a int, b int, KEY (b));
+INSERT INTO t2 VALUES (100,NULL),(150,200);
+set join_cache_level = 5;
+explain SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
+1	SIMPLE	t2	ref	b	b	5	test.t1.b	2	Using where; Using join buffer
+SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+a
+NULL
+NULL
+set join_cache_level = 8;
+explain SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
+1	SIMPLE	t2	ref	b	b	5	test.t1.b	2	Using where; Using join buffer
+SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+a
+NULL
+NULL
+delete from t1;
+INSERT INTO t1 VALUES (NULL),(NULL);
+set join_cache_level = 5;
+explain SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
+1	SIMPLE	t2	ref	b	b	5	test.t1.b	2	Using where; Using join buffer
+SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+a
+NULL
+NULL
+DROP TABLE t1,t2;
+CREATE TABLE t1 (b varchar(100));
+INSERT INTO t1 VALUES (NULL),("some varchar");
+CREATE TABLE t2 (a int, b varchar(100), KEY (b));
+INSERT INTO t2 VALUES (100,NULL),(150,"varchar"),(200,NULL),(250,"long long varchar");
+set join_cache_level = 5;
+explain SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
+1	SIMPLE	t2	ref	b	b	103	test.t1.b	2	Using where; Using join buffer
+SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+a
+NULL
+NULL
+set join_cache_level = 8;
+explain SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
+1	SIMPLE	t2	ref	b	b	103	test.t1.b	2	Using where; Using join buffer
+SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+a
+NULL
+NULL
+set join_cache_level = default;
+DROP TABLE t1,t2;
 set @@optimizer_switch=@save_optimizer_switch;

mysql-test/r/join_outer.result

@@ -1126,7 +1126,7 @@ a	b	a	b
 7	8	7	5
 EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a = t2.a OR t1.a = t2.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	ALL	PRIMARY	NULL	NULL	NULL	4	
+1	SIMPLE	t2	ALL	PRIMARY	NULL	NULL	NULL	4	Using where
 1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t2.a	1	
 EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a IN(t2.a, t2.b);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

mysql-test/r/join_outer_jcl6.result

@@ -1133,7 +1133,7 @@ a	b	a	b
 7	8	7	5
 EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a = t2.a OR t1.a = t2.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	ALL	PRIMARY	NULL	NULL	NULL	4	
+1	SIMPLE	t2	ALL	PRIMARY	NULL	NULL	NULL	4	Using where
 1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t2.a	1	Using join buffer
 EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a IN(t2.a, t2.b);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

mysql-test/r/key_cache.result

@@ -642,7 +642,7 @@ i
 3
 explain select count(*) from t1, t2 where t1.p = t2.i;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	index	k1	k1	5	NULL	1024	Using index
+1	SIMPLE	t2	index	k1	k1	5	NULL	1024	Using where; Using index
 1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t2.i	1	Using index
 select count(*) from t1, t2 where t1.p = t2.i;
 count(*)

mysql-test/r/myisam.result

@@ -357,7 +357,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ref	a	a	4	test.t2.a	3	
 explain select * from t1,t2 where t1.b=t2.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	ALL	b	NULL	NULL	NULL	2	
+1	SIMPLE	t2	ALL	b	NULL	NULL	NULL	2	Using where
 1	SIMPLE	t1	ref	b	b	5	test.t2.b	1	
 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

mysql-test/r/null_key.result

@@ -178,12 +178,12 @@ create table t2 (a int);
 insert into t2 values (7),(8);
 explain select * from t2 straight_join t1 where t1.a=t2.a and b is null;
 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 where
 1	SIMPLE	t1	ref	a,b	a	10	test.t2.a,const	2	Using where; Using index
 drop index b on t1;
 explain select * from t2,t1 where t1.a=t2.a and b is null;
 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 where
 1	SIMPLE	t1	ref	a	a	10	test.t2.a,const	2	Using where; Using index
 select * from t2,t1 where t1.a=t2.a and b is null;
 a	a	b
@@ -191,7 +191,7 @@ a	a	b
 8	8	NULL
 explain select * from t2,t1 where t1.a=t2.a and (b= 7 or b is null);
 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 where
 1	SIMPLE	t1	ref_or_null	a	a	10	test.t2.a,const	4	Using index
 select * from t2,t1 where t1.a=t2.a and (b= 7 or b is null);
 a	a	b
@@ -407,8 +407,8 @@ EXPLAIN SELECT SQL_CALC_FOUND_ROWS * FROM t1 LEFT JOIN t2 ON t1.a=t2.a
 LEFT JOIN t3 ON t2.b=t3.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
-1	SIMPLE	t2	ref	idx	idx	5	test.t1.a	1	
-1	SIMPLE	t3	ref	idx	idx	5	test.t2.b	1	Using index
+1	SIMPLE	t2	ref	idx	idx	5	test.t1.a	1	Using where
+1	SIMPLE	t3	ref	idx	idx	5	test.t2.b	1	Using where; Using index
 FLUSH STATUS ;
 SELECT SQL_CALC_FOUND_ROWS * FROM t1 LEFT JOIN t2 ON t1.a=t2.a
 LEFT JOIN t3 ON t2.b=t3.b;
@@ -423,8 +423,8 @@ FOUND_ROWS()
 SHOW STATUS LIKE "handler_read%";
 Variable_name	Value
 Handler_read_first	0
-Handler_read_key	6
-Handler_read_next	2
+Handler_read_key	8
+Handler_read_next	31942
 Handler_read_prev	0
 Handler_read_rnd	0
 Handler_read_rnd_next	5

mysql-test/r/order_by.result

@@ -1489,7 +1489,7 @@ SELECT d FROM t1, t2
 WHERE t2.b=14 AND t2.a=t1.a AND 5.1<t2.c AND t1.b='DE'
 ORDER BY t2.c LIMIT 1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	a,b	b	4	const	4	Using index condition; Using temporary; Using filesort
+1	SIMPLE	t1	ref	a,b	b	4	const	4	Using index condition; Using where; Using temporary; Using filesort
 1	SIMPLE	t2	ref	a,b,c	a	40	test.t1.a,const	11	Using index condition
 SELECT d FROM t1, t2
 WHERE t2.b=14 AND t2.a=t1.a AND 5.1<t2.c AND t1.b='DE'

mysql-test/r/select.result

@@ -3562,19 +3562,19 @@ EXPLAIN SELECT t2.*
 FROM t1 JOIN t2 ON t2.fk=t1.pk
 WHERE t2.fk < 'c' AND t2.pk=t1.fk;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	3	Using index condition; Using MRR
+1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	3	Using index condition; Using where; Using MRR
 1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	18	test.t1.fk	1	Using where
 EXPLAIN SELECT t2.* 
 FROM t1 JOIN t2 ON t2.fk=t1.pk 
 WHERE t2.fk BETWEEN 'a' AND 'b' AND t2.pk=t1.fk;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	2	Using index condition; Using MRR
+1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	2	Using index condition; Using where; Using MRR
 1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	18	test.t1.fk	1	Using where
 EXPLAIN SELECT t2.* 
 FROM t1 JOIN t2 ON t2.fk=t1.pk 
 WHERE t2.fk IN ('a','b') AND t2.pk=t1.fk;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	2	Using index condition; Using MRR
+1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	2	Using index condition; Using where; Using MRR
 1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	18	test.t1.fk	1	Using where
 DROP TABLE t1,t2;
 CREATE TABLE t1 (a int, b varchar(20) NOT NULL, PRIMARY KEY(a));
@@ -3608,7 +3608,7 @@ WHERE t1.id = 8 AND t2.i BETWEEN t1.b AND t1.e AND
 t3.a=t2.a AND t3.c IN ('bb','ee');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	const	PRIMARY	PRIMARY	4	const	1	
-1	SIMPLE	t2	range	si	si	5	NULL	4	Using index condition; Using MRR
+1	SIMPLE	t2	range	si	si	5	NULL	4	Using index condition; Using where; Using MRR
 1	SIMPLE	t3	eq_ref	PRIMARY,ci	PRIMARY	4	test.t2.a	1	Using where
 EXPLAIN
 SELECT t3.a FROM t1,t2,t3
@@ -3616,7 +3616,7 @@ WHERE t1.id = 8 AND t2.i BETWEEN t1.b AND t1.e AND
 t3.a=t2.a AND t3.c IN ('bb','ee') ;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	const	PRIMARY	PRIMARY	4	const	1	
-1	SIMPLE	t2	range	si,ai	si	5	NULL	4	Using index condition; Using MRR
+1	SIMPLE	t2	range	si,ai	si	5	NULL	4	Using index condition; Using where; Using MRR
 1	SIMPLE	t3	eq_ref	PRIMARY,ci	PRIMARY	4	test.t2.a	1	Using where
 EXPLAIN 
 SELECT t3.a FROM t1,t2 FORCE INDEX (si),t3
@@ -3624,7 +3624,7 @@ WHERE t1.id = 8 AND (t2.i=t1.b OR t2.i=t1.e) AND t3.a=t2.a AND
 t3.c IN ('bb','ee');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	const	PRIMARY	PRIMARY	4	const	1	
-1	SIMPLE	t2	range	si	si	5	NULL	2	Using index condition; Using MRR
+1	SIMPLE	t2	range	si	si	5	NULL	2	Using index condition; Using where; Using MRR
 1	SIMPLE	t3	eq_ref	PRIMARY,ci	PRIMARY	4	test.t2.a	1	Using where
 EXPLAIN 
 SELECT t3.a FROM t1,t2,t3
@@ -3632,7 +3632,7 @@ WHERE t1.id = 8 AND (t2.i=t1.b OR t2.i=t1.e) AND t3.a=t2.a AND
 t3.c IN ('bb','ee');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	const	PRIMARY	PRIMARY	4	const	1	
-1	SIMPLE	t2	range	si,ai	si	5	NULL	2	Using index condition; Using MRR
+1	SIMPLE	t2	range	si,ai	si	5	NULL	2	Using index condition; Using where; Using MRR
 1	SIMPLE	t3	eq_ref	PRIMARY,ci	PRIMARY	4	test.t2.a	1	Using where
 DROP TABLE t1,t2,t3;
 CREATE TABLE t1 ( f1 int primary key, f2 int, f3 int, f4 int, f5 int, f6 int, checked_out int);

mysql-test/r/select_jcl6.result

@@ -3569,19 +3569,19 @@ EXPLAIN SELECT t2.*
 FROM t1 JOIN t2 ON t2.fk=t1.pk
 WHERE t2.fk < 'c' AND t2.pk=t1.fk;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	3	Using index condition; Using MRR
+1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	3	Using index condition; Using where; Using MRR
 1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	18	test.t1.fk	1	Using where; Using join buffer
 EXPLAIN SELECT t2.* 
 FROM t1 JOIN t2 ON t2.fk=t1.pk 
 WHERE t2.fk BETWEEN 'a' AND 'b' AND t2.pk=t1.fk;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	2	Using index condition; Using MRR
+1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	2	Using index condition; Using where; Using MRR
 1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	18	test.t1.fk	1	Using where; Using join buffer
 EXPLAIN SELECT t2.* 
 FROM t1 JOIN t2 ON t2.fk=t1.pk 
 WHERE t2.fk IN ('a','b') AND t2.pk=t1.fk;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	2	Using index condition; Using MRR
+1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	2	Using index condition; Using where; Using MRR
 1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	18	test.t1.fk	1	Using where; Using join buffer
 DROP TABLE t1,t2;
 CREATE TABLE t1 (a int, b varchar(20) NOT NULL, PRIMARY KEY(a));
@@ -3615,7 +3615,7 @@ WHERE t1.id = 8 AND t2.i BETWEEN t1.b AND t1.e AND
 t3.a=t2.a AND t3.c IN ('bb','ee');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	const	PRIMARY	PRIMARY	4	const	1	
-1	SIMPLE	t2	range	si	si	5	NULL	4	Using index condition; Using MRR
+1	SIMPLE	t2	range	si	si	5	NULL	4	Using index condition; Using where; Using MRR
 1	SIMPLE	t3	eq_ref	PRIMARY,ci	PRIMARY	4	test.t2.a	1	Using where; Using join buffer
 EXPLAIN
 SELECT t3.a FROM t1,t2,t3
@@ -3623,7 +3623,7 @@ WHERE t1.id = 8 AND t2.i BETWEEN t1.b AND t1.e AND
 t3.a=t2.a AND t3.c IN ('bb','ee') ;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	const	PRIMARY	PRIMARY	4	const	1	
-1	SIMPLE	t2	range	si,ai	si	5	NULL	4	Using index condition; Using MRR
+1	SIMPLE	t2	range	si,ai	si	5	NULL	4	Using index condition; Using where; Using MRR
 1	SIMPLE	t3	eq_ref	PRIMARY,ci	PRIMARY	4	test.t2.a	1	Using where; Using join buffer
 EXPLAIN 
 SELECT t3.a FROM t1,t2 FORCE INDEX (si),t3
@@ -3631,7 +3631,7 @@ WHERE t1.id = 8 AND (t2.i=t1.b OR t2.i=t1.e) AND t3.a=t2.a AND
 t3.c IN ('bb','ee');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	const	PRIMARY	PRIMARY	4	const	1	
-1	SIMPLE	t2	range	si	si	5	NULL	2	Using index condition; Using MRR
+1	SIMPLE	t2	range	si	si	5	NULL	2	Using index condition; Using where; Using MRR
 1	SIMPLE	t3	eq_ref	PRIMARY,ci	PRIMARY	4	test.t2.a	1	Using where; Using join buffer
 EXPLAIN 
 SELECT t3.a FROM t1,t2,t3
@@ -3639,7 +3639,7 @@ WHERE t1.id = 8 AND (t2.i=t1.b OR t2.i=t1.e) AND t3.a=t2.a AND
 t3.c IN ('bb','ee');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	const	PRIMARY	PRIMARY	4	const	1	
-1	SIMPLE	t2	range	si,ai	si	5	NULL	2	Using index condition; Using MRR
+1	SIMPLE	t2	range	si,ai	si	5	NULL	2	Using index condition; Using where; Using MRR
 1	SIMPLE	t3	eq_ref	PRIMARY,ci	PRIMARY	4	test.t2.a	1	Using where; Using join buffer
 DROP TABLE t1,t2,t3;
 CREATE TABLE t1 ( f1 int primary key, f2 int, f3 int, f4 int, f5 int, f6 int, checked_out int);

mysql-test/r/select_pkeycache.result

@@ -3562,19 +3562,19 @@ EXPLAIN SELECT t2.*
 FROM t1 JOIN t2 ON t2.fk=t1.pk
 WHERE t2.fk < 'c' AND t2.pk=t1.fk;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	3	Using index condition; Using MRR
+1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	3	Using index condition; Using where; Using MRR
 1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	18	test.t1.fk	1	Using where
 EXPLAIN SELECT t2.* 
 FROM t1 JOIN t2 ON t2.fk=t1.pk 
 WHERE t2.fk BETWEEN 'a' AND 'b' AND t2.pk=t1.fk;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	2	Using index condition; Using MRR
+1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	2	Using index condition; Using where; Using MRR
 1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	18	test.t1.fk	1	Using where
 EXPLAIN SELECT t2.* 
 FROM t1 JOIN t2 ON t2.fk=t1.pk 
 WHERE t2.fk IN ('a','b') AND t2.pk=t1.fk;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	2	Using index condition; Using MRR
+1	SIMPLE	t1	range	PRIMARY	PRIMARY	12	NULL	2	Using index condition; Using where; Using MRR
 1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	18	test.t1.fk	1	Using where
 DROP TABLE t1,t2;
 CREATE TABLE t1 (a int, b varchar(20) NOT NULL, PRIMARY KEY(a));
@@ -3608,7 +3608,7 @@ WHERE t1.id = 8 AND t2.i BETWEEN t1.b AND t1.e AND
 t3.a=t2.a AND t3.c IN ('bb','ee');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	const	PRIMARY	PRIMARY	4	const	1	
-1	SIMPLE	t2	range	si	si	5	NULL	4	Using index condition; Using MRR
+1	SIMPLE	t2	range	si	si	5	NULL	4	Using index condition; Using where; Using MRR
 1	SIMPLE	t3	eq_ref	PRIMARY,ci	PRIMARY	4	test.t2.a	1	Using where
 EXPLAIN
 SELECT t3.a FROM t1,t2,t3
@@ -3616,7 +3616,7 @@ WHERE t1.id = 8 AND t2.i BETWEEN t1.b AND t1.e AND
 t3.a=t2.a AND t3.c IN ('bb','ee') ;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	const	PRIMARY	PRIMARY	4	const	1	
-1	SIMPLE	t2	range	si,ai	si	5	NULL	4	Using index condition; Using MRR
+1	SIMPLE	t2	range	si,ai	si	5	NULL	4	Using index condition; Using where; Using MRR
 1	SIMPLE	t3	eq_ref	PRIMARY,ci	PRIMARY	4	test.t2.a	1	Using where
 EXPLAIN 
 SELECT t3.a FROM t1,t2 FORCE INDEX (si),t3
@@ -3624,7 +3624,7 @@ WHERE t1.id = 8 AND (t2.i=t1.b OR t2.i=t1.e) AND t3.a=t2.a AND
 t3.c IN ('bb','ee');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	const	PRIMARY	PRIMARY	4	const	1	
-1	SIMPLE	t2	range	si	si	5	NULL	2	Using index condition; Using MRR
+1	SIMPLE	t2	range	si	si	5	NULL	2	Using index condition; Using where; Using MRR
 1	SIMPLE	t3	eq_ref	PRIMARY,ci	PRIMARY	4	test.t2.a	1	Using where
 EXPLAIN 
 SELECT t3.a FROM t1,t2,t3
@@ -3632,7 +3632,7 @@ WHERE t1.id = 8 AND (t2.i=t1.b OR t2.i=t1.e) AND t3.a=t2.a AND
 t3.c IN ('bb','ee');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	const	PRIMARY	PRIMARY	4	const	1	
-1	SIMPLE	t2	range	si,ai	si	5	NULL	2	Using index condition; Using MRR
+1	SIMPLE	t2	range	si,ai	si	5	NULL	2	Using index condition; Using where; Using MRR
 1	SIMPLE	t3	eq_ref	PRIMARY,ci	PRIMARY	4	test.t2.a	1	Using where
 DROP TABLE t1,t2,t3;
 CREATE TABLE t1 ( f1 int primary key, f2 int, f3 int, f4 int, f5 int, f6 int, checked_out int);

mysql-test/r/select_safe.result

@@ -66,12 +66,12 @@ test.t1	analyze	status	OK
 insert into t1 values (null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a");
 explain select STRAIGHT_JOIN * from t1,t1 as t2 where t1.b=t2.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	b	NULL	NULL	NULL	21	
+1	SIMPLE	t1	ALL	b	NULL	NULL	NULL	21	Using where
 1	SIMPLE	t2	ref	b	b	21	test.t1.b	6	
 set MAX_SEEKS_FOR_KEY=1;
 explain select STRAIGHT_JOIN * from t1,t1 as t2 where t1.b=t2.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	b	NULL	NULL	NULL	21	
+1	SIMPLE	t1	ALL	b	NULL	NULL	NULL	21	Using where
 1	SIMPLE	t2	ref	b	b	21	test.t1.b	6	
 SET MAX_SEEKS_FOR_KEY=DEFAULT;
 drop table t1;

mysql-test/r/subselect.result

@@ -1338,7 +1338,7 @@ a
 4
 explain extended select * from t2 where t2.a in (select a from t1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	PRIMARY	t2	index	a	a	5	NULL	4	100.00	Using index
+1	PRIMARY	t2	index	a	a	5	NULL	4	100.00	Using where; Using index
 1	PRIMARY	t1	ref	a	a	5	test.t2.a	101	100.00	Using index; FirstMatch(t2)
 Warnings:
 Note	1003	select `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t1`) where (`test`.`t1`.`a` = `test`.`t2`.`a`)
@@ -1348,7 +1348,7 @@ a
 4
 explain extended 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	filtered	Extra
-1	PRIMARY	t2	index	a	a	5	NULL	4	100.00	Using index
+1	PRIMARY	t2	index	a	a	5	NULL	4	100.00	Using where; Using index
 1	PRIMARY	t1	ref	a	a	5	test.t2.a	101	100.00	Using where; Using index; FirstMatch(t2)
 Warnings:
 Note	1003	select `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t1`) where ((`test`.`t1`.`a` = `test`.`t2`.`a`) and (`test`.`t1`.`b` <> 30))
@@ -1358,8 +1358,8 @@ a
 3
 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	a	a	5	NULL	4	100.00	Using index
-1	PRIMARY	t3	index	a	a	5	NULL	3	100.00	Using index
+1	PRIMARY	t2	index	a	a	5	NULL	4	100.00	Using where; Using index
+1	PRIMARY	t3	index	a	a	5	NULL	3	100.00	Using where; Using index
 1	PRIMARY	t1	ref	a	a	10	test.t2.a,test.t3.a	116	100.61	Using index; FirstMatch(t2)
 Warnings:
 Note	1003	select `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t1` join `test`.`t3`) where ((`test`.`t1`.`a` = `test`.`t2`.`a`) and (`test`.`t1`.`b` = `test`.`t3`.`a`))
@@ -1375,7 +1375,7 @@ a
 4
 explain extended 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	filtered	Extra
-1	PRIMARY	t2	index	a	a	5	NULL	4	100.00	Using index
+1	PRIMARY	t2	index	a	a	5	NULL	4	100.00	Using where; Using index
 1	PRIMARY	t1	ref	a	a	5	test.t2.a	101	100.00	Using where; Using index; FirstMatch(t2)
 Warnings:
 Note	1003	select `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t1`) where ((`test`.`t1`.`a` = `test`.`t2`.`a`) and (`test`.`t1`.`b` <> 30))
@@ -4202,7 +4202,7 @@ CREATE INDEX I1 ON t1 (a);
 CREATE INDEX I2 ON t1 (b);
 EXPLAIN SELECT a,b FROM t1 WHERE b IN (SELECT a FROM t1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t1	index	I1	I1	2	NULL	2	Using index; LooseScan
+1	PRIMARY	t1	index	I1	I1	2	NULL	2	Using where; Using index; LooseScan
 1	PRIMARY	t1	ref	I2	I2	13	test.t1.a	2	Using index condition
 SELECT a,b FROM t1 WHERE b IN (SELECT a FROM t1);
 a	b
@@ -4212,7 +4212,7 @@ CREATE INDEX I1 ON t2 (a);
 CREATE INDEX I2 ON t2 (b);
 EXPLAIN SELECT a,b FROM t2 WHERE b IN (SELECT a FROM t2);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t2	index	I1	I1	4	NULL	2	Using index; LooseScan
+1	PRIMARY	t2	index	I1	I1	4	NULL	2	Using where; Using index; LooseScan
 1	PRIMARY	t2	ref	I2	I2	13	test.t2.a	2	Using index condition
 SELECT a,b FROM t2 WHERE b IN (SELECT a FROM t2);
 a	b

mysql-test/r/subselect3.result

@@ -1131,7 +1131,7 @@ insert into t4 select a from t3;
 explain select * from t3 where a in (select t1.kp1 from t1,t4 where kp1<20
 and t4.pk=t1.c);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t1	range	kp1	kp1	5	NULL	48	Using index condition; Using MRR; LooseScan
+1	PRIMARY	t1	range	kp1	kp1	5	NULL	48	Using index condition; Using where; Using MRR; LooseScan
 1	PRIMARY	t4	eq_ref	PRIMARY	PRIMARY	4	test.t1.c	1	Using index; FirstMatch(t1)
 1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	100	Using where; Using join buffer
 drop table t1, t3, t4;

mysql-test/r/subselect3_jcl6.result

@@ -1139,7 +1139,7 @@ insert into t4 select a from t3;
 explain select * from t3 where a in (select t1.kp1 from t1,t4 where kp1<20
 and t4.pk=t1.c);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t1	range	kp1	kp1	5	NULL	48	Using index condition; Using MRR; LooseScan
+1	PRIMARY	t1	range	kp1	kp1	5	NULL	48	Using index condition; Using where; Using MRR; LooseScan
 1	PRIMARY	t4	eq_ref	PRIMARY	PRIMARY	4	test.t1.c	1	Using index; FirstMatch(t1)
 1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	100	Using where; Using join buffer
 drop table t1, t3, t4;

mysql-test/r/subselect_no_mat.result

@@ -1342,7 +1342,7 @@ a
 4
 explain extended select * from t2 where t2.a in (select a from t1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	PRIMARY	t2	index	a	a	5	NULL	4	100.00	Using index
+1	PRIMARY	t2	index	a	a	5	NULL	4	100.00	Using where; Using index
 1	PRIMARY	t1	ref	a	a	5	test.t2.a	101	100.00	Using index; FirstMatch(t2)
 Warnings:
 Note	1003	select `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t1`) where (`test`.`t1`.`a` = `test`.`t2`.`a`)
@@ -1352,7 +1352,7 @@ a
 4
 explain extended 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	filtered	Extra
-1	PRIMARY	t2	index	a	a	5	NULL	4	100.00	Using index
+1	PRIMARY	t2	index	a	a	5	NULL	4	100.00	Using where; Using index
 1	PRIMARY	t1	ref	a	a	5	test.t2.a	101	100.00	Using where; Using index; FirstMatch(t2)
 Warnings:
 Note	1003	select `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t1`) where ((`test`.`t1`.`a` = `test`.`t2`.`a`) and (`test`.`t1`.`b` <> 30))
@@ -1362,8 +1362,8 @@ a
 3
 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	a	a	5	NULL	4	100.00	Using index
-1	PRIMARY	t3	index	a	a	5	NULL	3	100.00	Using index
+1	PRIMARY	t2	index	a	a	5	NULL	4	100.00	Using where; Using index
+1	PRIMARY	t3	index	a	a	5	NULL	3	100.00	Using where; Using index
 1	PRIMARY	t1	ref	a	a	10	test.t2.a,test.t3.a	116	100.61	Using index; FirstMatch(t2)
 Warnings:
 Note	1003	select `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t1` join `test`.`t3`) where ((`test`.`t1`.`a` = `test`.`t2`.`a`) and (`test`.`t1`.`b` = `test`.`t3`.`a`))
@@ -1379,7 +1379,7 @@ a
 4
 explain extended 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	filtered	Extra
-1	PRIMARY	t2	index	a	a	5	NULL	4	100.00	Using index
+1	PRIMARY	t2	index	a	a	5	NULL	4	100.00	Using where; Using index
 1	PRIMARY	t1	ref	a	a	5	test.t2.a	101	100.00	Using where; Using index; FirstMatch(t2)
 Warnings:
 Note	1003	select `test`.`t2`.`a` AS `a` from `test`.`t2` semi join (`test`.`t1`) where ((`test`.`t1`.`a` = `test`.`t2`.`a`) and (`test`.`t1`.`b` <> 30))
@@ -4206,7 +4206,7 @@ CREATE INDEX I1 ON t1 (a);
 CREATE INDEX I2 ON t1 (b);
 EXPLAIN SELECT a,b FROM t1 WHERE b IN (SELECT a FROM t1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t1	index	I1	I1	2	NULL	2	Using index; LooseScan
+1	PRIMARY	t1	index	I1	I1	2	NULL	2	Using where; Using index; LooseScan
 1	PRIMARY	t1	ref	I2	I2	13	test.t1.a	2	Using index condition
 SELECT a,b FROM t1 WHERE b IN (SELECT a FROM t1);
 a	b
@@ -4216,7 +4216,7 @@ CREATE INDEX I1 ON t2 (a);
 CREATE INDEX I2 ON t2 (b);
 EXPLAIN SELECT a,b FROM t2 WHERE b IN (SELECT a FROM t2);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t2	index	I1	I1	4	NULL	2	Using index; LooseScan
+1	PRIMARY	t2	index	I1	I1	4	NULL	2	Using where; Using index; LooseScan
 1	PRIMARY	t2	ref	I2	I2	13	test.t2.a	2	Using index condition
 SELECT a,b FROM t2 WHERE b IN (SELECT a FROM t2);
 a	b

mysql-test/r/subselect_no_opts.result

@@ -1317,7 +1317,7 @@ 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	PRIMARY	4	NULL	4	100.00	Using where; Using index
-2	DEPENDENT SUBQUERY	t1	eq_ref	PRIMARY	PRIMARY	4	func	1	100.00	
+2	DEPENDENT SUBQUERY	t1	eq_ref	PRIMARY	PRIMARY	4	func	1	100.00	Using where
 2	DEPENDENT SUBQUERY	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.b	1	100.00	Using index
 Warnings:
 Note	1003	select `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(select 1 from `test`.`t1` join `test`.`t3` where ((`test`.`t3`.`a` = `test`.`t1`.`b`) and (<cache>(`test`.`t2`.`a`) = `test`.`t1`.`a`))))

mysql-test/r/subselect_sj.result

@@ -13,7 +13,7 @@ insert into t12 select * from t10;
 Flattened because of dependency, t10=func(t1)
 explain select * from t1 where a in (select pk from t10);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 1	PRIMARY	t10	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using index
 select * from t1 where a in (select pk from t10);
 a	b
@@ -40,7 +40,7 @@ select * from t1 where a in (select a from t11);
 a	b
 explain select * from t1 where a in (select pk from t10) and b in (select pk from t10);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 1	PRIMARY	t10	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using index
 1	PRIMARY	t10	eq_ref	PRIMARY	PRIMARY	4	test.t1.b	1	Using index
 select * from t1 where a in (select pk from t10) and b in (select pk from t10);
@@ -51,8 +51,8 @@ a	b
 flattening a nested subquery
 explain select * from t1 where a in (select pk from t10 where t10.a in (select pk from t12));
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	
-1	PRIMARY	t10	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
+1	PRIMARY	t10	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where
 1	PRIMARY	t12	eq_ref	PRIMARY	PRIMARY	4	test.t10.a	1	Using index
 select * from t1 where a in (select pk from t10 where t10.a in (select pk from t12));
 a	b
@@ -62,8 +62,8 @@ a	b
 flattening subquery w/ several tables
 explain extended select * from t1 where a in (select t10.pk from t10, t12 where t12.pk=t10.a);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	
-1	PRIMARY	t10	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	100.00	
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
+1	PRIMARY	t10	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	100.00	Using where
 1	PRIMARY	t12	eq_ref	PRIMARY	PRIMARY	4	test.t10.a	1	100.00	Using index
 Warnings:
 Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t10` join `test`.`t12` join `test`.`t1` where ((`test`.`t10`.`pk` = `test`.`t1`.`a`) and (`test`.`t12`.`pk` = `test`.`t10`.`a`))
@@ -508,7 +508,7 @@ EXPLAIN EXTENDED SELECT vkey FROM t0 WHERE pk IN
 (SELECT t1.pk FROM t0 t1 JOIN t0 t2 ON t2.vkey = t1.vnokey);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	PRIMARY	t0	ALL	PRIMARY	NULL	NULL	NULL	5	100.00	
-1	PRIMARY	t1	eq_ref	PRIMARY	PRIMARY	4	test.t0.pk	1	100.00	
+1	PRIMARY	t1	eq_ref	PRIMARY	PRIMARY	4	test.t0.pk	1	100.00	Using where
 1	PRIMARY	t2	ref	vkey	vkey	4	test.t1.vnokey	2	100.00	Using index; FirstMatch(t1)
 Warnings:
 Note	1003	select `test`.`t0`.`vkey` AS `vkey` from `test`.`t0` `t1` semi join (`test`.`t0` `t2`) join `test`.`t0` where ((`test`.`t2`.`vkey` = `test`.`t1`.`vnokey`) and (`test`.`t1`.`pk` = `test`.`t0`.`pk`))

mysql-test/r/subselect_sj2.result

@@ -34,7 +34,7 @@ explain select * from t2 where b in (select a from t1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	subselect2	ALL	unique_key	NULL	NULL	NULL	3	
 1	PRIMARY	t2	ref	b	b	5	test.t1.a	2	
-2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	3	
+2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 select * from t2 where b in (select a from t1);
 a	b
 1	1
@@ -76,7 +76,7 @@ explain select * from t3 where b in (select a from t0);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	subselect2	ALL	unique_key	NULL	NULL	NULL	10	
 1	PRIMARY	t3	ref	b	b	5	test.t0.a	1	
-2	SUBQUERY	t0	ALL	NULL	NULL	NULL	NULL	10	
+2	SUBQUERY	t0	ALL	NULL	NULL	NULL	NULL	10	Using where
 set @save_ecp= @@engine_condition_pushdown;
 set engine_condition_pushdown=0;
 select * from t3 where b in (select A.a+B.a from t0 A, t0 B where B.a<5);
@@ -273,7 +273,7 @@ from t0 where a in
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t0	ALL	NULL	NULL	NULL	NULL	10	Start temporary
 1	PRIMARY	t1	index	NULL	a	5	NULL	10	Using index; Using join buffer
-1	PRIMARY	t2	ref	a	a	5	test.t1.a	1	Using index
+1	PRIMARY	t2	ref	a	a	5	test.t1.a	1	Using where; Using index
 1	PRIMARY	t3	ref	a	a	5	test.t1.a	1	Using where; Using index; End temporary
 drop table t0, t1,t2,t3;
 CREATE TABLE t1 (
@@ -425,7 +425,7 @@ explain extended select * from t0
 where t0.a in ( select t1.a from t1,t2 where t2.a=t0.a and
 t1.b=t2.b);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	PRIMARY	t0	ALL	NULL	NULL	NULL	NULL	5	100.00	
+1	PRIMARY	t0	ALL	NULL	NULL	NULL	NULL	5	100.00	Using where
 1	PRIMARY	t1	ref	a	a	5	test.t0.a	1	100.00	Start temporary
 1	PRIMARY	t2	eq_ref	PRIMARY	PRIMARY	4	test.t0.a	1	100.00	Using where; End temporary
 Warnings:

mysql-test/r/subselect_sj2_jcl6.result

@@ -41,7 +41,7 @@ explain select * from t2 where b in (select a from t1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	subselect2	ALL	unique_key	NULL	NULL	NULL	3	
 1	PRIMARY	t2	ref	b	b	5	test.t1.a	2	Using join buffer
-2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	3	
+2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 select * from t2 where b in (select a from t1);
 a	b
 1	1
@@ -83,7 +83,7 @@ explain select * from t3 where b in (select a from t0);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	subselect2	ALL	unique_key	NULL	NULL	NULL	10	
 1	PRIMARY	t3	ref	b	b	5	test.t0.a	1	Using join buffer
-2	SUBQUERY	t0	ALL	NULL	NULL	NULL	NULL	10	
+2	SUBQUERY	t0	ALL	NULL	NULL	NULL	NULL	10	Using where
 set @save_ecp= @@engine_condition_pushdown;
 set engine_condition_pushdown=0;
 select * from t3 where b in (select A.a+B.a from t0 A, t0 B where B.a<5);
@@ -280,7 +280,7 @@ from t0 where a in
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t0	ALL	NULL	NULL	NULL	NULL	10	Start temporary
 1	PRIMARY	t1	index	NULL	a	5	NULL	10	Using index; Using join buffer
-1	PRIMARY	t2	ref	a	a	5	test.t1.a	1	Using index
+1	PRIMARY	t2	ref	a	a	5	test.t1.a	1	Using where; Using index
 1	PRIMARY	t3	ref	a	a	5	test.t1.a	1	Using where; Using index; End temporary
 drop table t0, t1,t2,t3;
 CREATE TABLE t1 (
@@ -432,7 +432,7 @@ explain extended select * from t0
 where t0.a in ( select t1.a from t1,t2 where t2.a=t0.a and
 t1.b=t2.b);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	PRIMARY	t0	ALL	NULL	NULL	NULL	NULL	5	100.00	Start temporary
+1	PRIMARY	t0	ALL	NULL	NULL	NULL	NULL	5	100.00	Using where; Start temporary
 1	PRIMARY	t1	ref	a	a	5	test.t0.a	1	100.00	Using join buffer
 1	PRIMARY	t2	eq_ref	PRIMARY	PRIMARY	4	test.t0.a	1	100.00	Using where; End temporary; Using join buffer
 Warnings:

mysql-test/r/subselect_sj_jcl6.result

@@ -20,7 +20,7 @@ insert into t12 select * from t10;
 Flattened because of dependency, t10=func(t1)
 explain select * from t1 where a in (select pk from t10);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 1	PRIMARY	t10	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using index
 select * from t1 where a in (select pk from t10);
 a	b
@@ -47,7 +47,7 @@ select * from t1 where a in (select a from t11);
 a	b
 explain select * from t1 where a in (select pk from t10) and b in (select pk from t10);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 1	PRIMARY	t10	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using index
 1	PRIMARY	t10	eq_ref	PRIMARY	PRIMARY	4	test.t1.b	1	Using index
 select * from t1 where a in (select pk from t10) and b in (select pk from t10);
@@ -58,8 +58,8 @@ a	b
 flattening a nested subquery
 explain select * from t1 where a in (select pk from t10 where t10.a in (select pk from t12));
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	
-1	PRIMARY	t10	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using join buffer
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
+1	PRIMARY	t10	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where; Using join buffer
 1	PRIMARY	t12	eq_ref	PRIMARY	PRIMARY	4	test.t10.a	1	Using index
 select * from t1 where a in (select pk from t10 where t10.a in (select pk from t12));
 a	b
@@ -69,8 +69,8 @@ a	b
 flattening subquery w/ several tables
 explain extended select * from t1 where a in (select t10.pk from t10, t12 where t12.pk=t10.a);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	
-1	PRIMARY	t10	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	100.00	Using join buffer
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
+1	PRIMARY	t10	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	100.00	Using where; Using join buffer
 1	PRIMARY	t12	eq_ref	PRIMARY	PRIMARY	4	test.t10.a	1	100.00	Using index
 Warnings:
 Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t10` join `test`.`t12` join `test`.`t1` where ((`test`.`t10`.`pk` = `test`.`t1`.`a`) and (`test`.`t12`.`pk` = `test`.`t10`.`a`))
@@ -515,7 +515,7 @@ EXPLAIN EXTENDED SELECT vkey FROM t0 WHERE pk IN
 (SELECT t1.pk FROM t0 t1 JOIN t0 t2 ON t2.vkey = t1.vnokey);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	PRIMARY	t0	ALL	PRIMARY	NULL	NULL	NULL	5	100.00	
-1	PRIMARY	t1	eq_ref	PRIMARY	PRIMARY	4	test.t0.pk	1	100.00	Using join buffer
+1	PRIMARY	t1	eq_ref	PRIMARY	PRIMARY	4	test.t0.pk	1	100.00	Using where; Using join buffer
 1	PRIMARY	t2	ref	vkey	vkey	4	test.t1.vnokey	2	100.00	Using index; FirstMatch(t1)
 Warnings:
 Note	1003	select `test`.`t0`.`vkey` AS `vkey` from `test`.`t0` `t1` semi join (`test`.`t0` `t2`) join `test`.`t0` where ((`test`.`t2`.`vkey` = `test`.`t1`.`vnokey`) and (`test`.`t1`.`pk` = `test`.`t0`.`pk`))
@@ -1103,7 +1103,7 @@ explain
 SELECT * FROM t0 WHERE t0.a IN 
 (SELECT t1.a FROM t1, t2 WHERE t2.a=t0.a AND t1.b=t2.b);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t0	ALL	NULL	NULL	NULL	NULL	5	Start temporary
+1	PRIMARY	t0	ALL	NULL	NULL	NULL	NULL	5	Using where; Start temporary
 1	PRIMARY	t1	ref	a	a	5	test.t0.a	1	Using join buffer
 1	PRIMARY	t2	eq_ref	PRIMARY	PRIMARY	4	test.t0.a	1	Using where; End temporary; Using join buffer
 SELECT * FROM t0 WHERE t0.a IN 

mysql-test/r/table_elim.result

@@ -26,17 +26,17 @@ a
 explain select * from t1 left join t2 on t2.a=t1.a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
-1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where
 # This will not be eliminated as t2.b is in in order list:
 explain select t1.a from t1 left join t2 on t2.a=t1.a order by t2.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using temporary; Using filesort
-1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where
 # This will not be eliminated as t2.b is in group list:
 explain select t1.a from t1 left join t2 on t2.a=t1.a group by t2.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using temporary; Using filesort
-1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where
 # This will not be eliminated as t2.b is in the WHERE
 explain select t1.a from t1 left join t2 on t2.a=t1.a where t2.b < 3 or t2.b is null;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -75,7 +75,7 @@ This must not use elimination:
 explain select count(1) from t1 left join t2 on t2.a=t1.a group by t2.a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using temporary; Using filesort
-1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using index
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where; Using index
 drop table t0, t1, t2, t3;
 create table t0 ( id integer, primary key (id));
 create table t1 (
@@ -128,7 +128,7 @@ Note	1003	select `f`.`id` AS `id` from `test`.`t0` `f` where (`f`.`id` in (1,2,3
 This should use facts and a1 tables:
 explain extended select id from v1 where attr1 between 12 and 14;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	PRIMARY	a1	range	PRIMARY,attr1	attr1	5	NULL	2	100.00	Using index condition; Using MRR
+1	PRIMARY	a1	range	PRIMARY,attr1	attr1	5	NULL	2	100.00	Using index condition; Using where; Using MRR
 1	PRIMARY	f	eq_ref	PRIMARY	PRIMARY	4	test.a1.id	1	100.00	Using index
 Warnings:
 Note	1276	Field or reference 'test.a2.id' of SELECT #3 was resolved in SELECT #1
@@ -156,7 +156,7 @@ Note	1003	select `f`.`id` AS `id` from `test`.`t0` `f` where (`f`.`id` in (1,2,3
 This should use facts and a1 tables:
 explain extended select id from v2 where attr1 between 12 and 14;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	PRIMARY	a1	range	PRIMARY,attr1	attr1	5	NULL	2	100.00	Using index condition; Using MRR
+1	PRIMARY	a1	range	PRIMARY,attr1	attr1	5	NULL	2	100.00	Using index condition; Using where; Using MRR
 1	PRIMARY	f	eq_ref	PRIMARY	PRIMARY	4	test.a1.id	1	100.00	Using index
 Warnings:
 Note	1276	Field or reference 'test.f.id' of SELECT #3 was resolved in SELECT #1
@@ -164,7 +164,7 @@ Note	1003	select `f`.`id` AS `id` from `test`.`t0` `f` join `test`.`t1` `a1` whe
 This should use facts, a2 and its subquery:
 explain extended select id from v2 where attr2 between 12 and 14;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	PRIMARY	a2	range	PRIMARY,attr2	attr2	5	NULL	5	100.00	Using index condition; Using MRR
+1	PRIMARY	a2	range	PRIMARY,attr2	attr2	5	NULL	5	100.00	Using index condition; Using where; Using MRR
 1	PRIMARY	f	eq_ref	PRIMARY	PRIMARY	4	test.a2.id	1	100.00	Using where; Using index
 3	DEPENDENT SUBQUERY	t2	ref	PRIMARY	PRIMARY	4	test.f.id	2	100.00	Using index
 Warnings:
@@ -217,7 +217,7 @@ explain
 select t1.*, t2.* from t1 left join (t2 left join t3 on t3.pk=t2.col) on t2.pk=t1.col;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
-1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.col	1	
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.col	1	Using where
 explain select t1.* 
 from 
 t1 left join ( t2 left join t3 on t3.pk=t2.col or t3.pk=t2.col) 
@@ -232,7 +232,7 @@ t1 left join
 on t2.pk=t1.col or t2.pk=t1.col;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
-1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.col	1	
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.col	1	Using where
 drop table t1, t2, t3;
 # 
 # Check things that look like functional dependencies but really are not

mysql-test/r/table_elim_debug.result

@@ -10,7 +10,7 @@ set optimizer_switch='table_elimination=off';
 explain select t1.a from t1 left join t2 on t2.a=t1.a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
-1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using index
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where; Using index
 set optimizer_switch='table_elimination=on';
 explain select t1.a from t1 left join t2 on t2.a=t1.a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

mysql-test/r/view.result

@@ -2341,11 +2341,11 @@ CREATE VIEW v1 AS SELECT t1.* FROM t1,t2 WHERE t1.a=t2.a AND t1.b=t2.b;
 CREATE VIEW v2 AS SELECT t3.* FROM t1,t3 WHERE t1.a=t3.a;
 EXPLAIN SELECT t1.* FROM t1 JOIN t2 WHERE t1.a=t2.a AND t1.b=t2.b AND t1.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 index
+1	SIMPLE	t1	ref	a	a	5	const	1	Using where; Using index
 1	SIMPLE	t2	ref	a	a	10	const,test.t1.b	1	Using index
 EXPLAIN SELECT * FROM v1 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 index
+1	SIMPLE	t1	ref	a	a	5	const	1	Using where; Using index
 1	SIMPLE	t2	ref	a	a	10	const,test.t1.b	1	Using index
 EXPLAIN SELECT * FROM v2 WHERE a=1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

mysql-test/suite/pbxt/r/distinct.result

@@ -173,7 +173,7 @@ INSERT INTO t2 values (1),(2),(3);
 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	t1	ALL	PRIMARY	NULL	NULL	NULL	4	Using where; Using temporary
 1	SIMPLE	t2	ref	a	a	4	test.t1.a	1	Using index
 1	SIMPLE	t3	ref	a	a	5	test.t1.b	1	Using index
 SELECT distinct t3.a FROM t3,t2,t1 WHERE t3.a=t1.b AND t1.a=t2.a;

mysql-test/suite/pbxt/r/group_by.result

@@ -856,7 +856,7 @@ explain
 SELECT straight_join sql_no_cache v1.a, v1.b, v1.real_b from t2, v1
 where t2.b=v1.a GROUP BY t2.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	index	b	b	2	NULL	10	Using index
+1	SIMPLE	t2	index	b	b	2	NULL	10	Using where; Using index
 1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	1	test.t2.b	1	
 SELECT straight_join sql_no_cache v1.a, v1.b, v1.real_b from t2, v1
 where t2.b=v1.a GROUP BY t2.b;

mysql-test/suite/pbxt/r/join.result

@@ -794,8 +794,8 @@ Z
 vv: Following query must use ALL(t1), eq_ref(A), eq_ref(B): vv
 explain select * from t1, t2 A, t2 B where A.a = t1.a and B.a=A.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	10	
-1	SIMPLE	A	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	10	Using where
+1	SIMPLE	A	eq_ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where
 1	SIMPLE	B	eq_ref	PRIMARY	PRIMARY	4	test.A.b	1	
 show status like '%cost%';
 Variable_name	Value

mysql-test/suite/pbxt/r/join_nested.result

@@ -854,7 +854,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t2	ref	idx_b	idx_b	5	test.t3.b	1	100.00	Using where
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	
 Warnings:
-Note	1003	select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b` from `test`.`t3` join `test`.`t4` left join (`test`.`t1` join `test`.`t2`) on(((`test`.`t3`.`a` = 1) and (`test`.`t3`.`b` = `test`.`t2`.`b`) and (`test`.`t2`.`b` = `test`.`t4`.`b`))) where 1
+Note	1003	select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b` from `test`.`t3` join `test`.`t4` left join (`test`.`t1` join `test`.`t2`) on((((`test`.`t3`.`a` = 1) and (`test`.`t3`.`b` = `test`.`t2`.`b`) and (`test`.`t2`.`b` = `test`.`t4`.`b`)) and (`test`.`t3`.`b` is not null))) where 1
 SELECT t2.a,t2.b,t3.a,t3.b,t4.a,t4.b
 FROM (t3,t4)
 LEFT JOIN              
@@ -966,7 +966,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t8	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 1	SIMPLE	t9	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where; Using join buffer
 Warnings:
-Note	1003	select `test`.`t0`.`a` AS `a`,`test`.`t0`.`b` AS `b`,`test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b`,`test`.`t5`.`a` AS `a`,`test`.`t5`.`b` AS `b`,`test`.`t6`.`a` AS `a`,`test`.`t6`.`b` AS `b`,`test`.`t7`.`a` AS `a`,`test`.`t7`.`b` AS `b`,`test`.`t8`.`a` AS `a`,`test`.`t8`.`b` AS `b`,`test`.`t9`.`a` AS `a`,`test`.`t9`.`b` AS `b` from `test`.`t0` join `test`.`t1` left join (`test`.`t2` left join (`test`.`t3` join `test`.`t4`) on(((`test`.`t4`.`b` = `test`.`t2`.`b`) and (`test`.`t3`.`a` = 1))) join `test`.`t5` left join (`test`.`t6` join `test`.`t7` left join `test`.`t8` on(((`test`.`t8`.`b` = `test`.`t5`.`b`) and (`test`.`t6`.`b` < 10)))) on(((`test`.`t7`.`b` = `test`.`t5`.`b`) and (`test`.`t6`.`b` >= 2)))) on((((`test`.`t3`.`b` = 2) or isnull(`test`.`t3`.`c`)) and ((`test`.`t6`.`b` = 2) or isnull(`test`.`t6`.`c`)) and ((`test`.`t5`.`b` = `test`.`t0`.`b`) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t6`.`c`) or isnull(`test`.`t8`.`c`)) and (`test`.`t1`.`a` <> 2))) join `test`.`t9` where ((`test`.`t9`.`a` = 1) and (`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t0`.`a` = 1) and ((`test`.`t2`.`a` >= 4) or isnull(`test`.`t2`.`c`)) and ((`test`.`t3`.`a` < 5) or isnull(`test`.`t3`.`c`)) and ((`test`.`t4`.`b` = `test`.`t3`.`b`) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t4`.`c`)) and ((`test`.`t5`.`a` >= 2) or isnull(`test`.`t5`.`c`)) and ((`test`.`t6`.`a` >= 4) or isnull(`test`.`t6`.`c`)) and ((`test`.`t7`.`a` <= 2) or isnull(`test`.`t7`.`c`)) and ((`test`.`t8`.`a` < 1) or isnull(`test`.`t8`.`c`)) and ((`test`.`t9`.`b` = `test`.`t8`.`b`) or isnull(`test`.`t8`.`c`)))
+Note	1003	select `test`.`t0`.`a` AS `a`,`test`.`t0`.`b` AS `b`,`test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b`,`test`.`t5`.`a` AS `a`,`test`.`t5`.`b` AS `b`,`test`.`t6`.`a` AS `a`,`test`.`t6`.`b` AS `b`,`test`.`t7`.`a` AS `a`,`test`.`t7`.`b` AS `b`,`test`.`t8`.`a` AS `a`,`test`.`t8`.`b` AS `b`,`test`.`t9`.`a` AS `a`,`test`.`t9`.`b` AS `b` from `test`.`t0` join `test`.`t1` left join (`test`.`t2` left join (`test`.`t3` join `test`.`t4`) on((((`test`.`t4`.`b` = `test`.`t2`.`b`) and (`test`.`t3`.`a` = 1)) and (`test`.`t2`.`b` is not null))) join `test`.`t5` left join (`test`.`t6` join `test`.`t7` left join `test`.`t8` on(((`test`.`t8`.`b` = `test`.`t5`.`b`) and (`test`.`t6`.`b` < 10)))) on(((`test`.`t7`.`b` = `test`.`t5`.`b`) and (`test`.`t6`.`b` >= 2)))) on((((`test`.`t3`.`b` = 2) or isnull(`test`.`t3`.`c`)) and ((`test`.`t6`.`b` = 2) or isnull(`test`.`t6`.`c`)) and ((`test`.`t5`.`b` = `test`.`t0`.`b`) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t6`.`c`) or isnull(`test`.`t8`.`c`)) and (`test`.`t1`.`a` <> 2))) join `test`.`t9` where ((`test`.`t9`.`a` = 1) and (`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t0`.`a` = 1) and ((`test`.`t2`.`a` >= 4) or isnull(`test`.`t2`.`c`)) and ((`test`.`t3`.`a` < 5) or isnull(`test`.`t3`.`c`)) and ((`test`.`t4`.`b` = `test`.`t3`.`b`) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t4`.`c`)) and ((`test`.`t5`.`a` >= 2) or isnull(`test`.`t5`.`c`)) and ((`test`.`t6`.`a` >= 4) or isnull(`test`.`t6`.`c`)) and ((`test`.`t7`.`a` <= 2) or isnull(`test`.`t7`.`c`)) and ((`test`.`t8`.`a` < 1) or isnull(`test`.`t8`.`c`)) and ((`test`.`t9`.`b` = `test`.`t8`.`b`) or isnull(`test`.`t8`.`c`)))
 CREATE INDEX idx_b ON t8(b);
 EXPLAIN
 SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b,
@@ -1209,7 +1209,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 EXPLAIN SELECT a, b, c FROM t1 LEFT JOIN (t2, t3) ON b < 3 and b = c;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	index	NULL	a	5	NULL	#	Using index
-1	SIMPLE	t3	index	c	c	5	NULL	#	Using index
+1	SIMPLE	t3	index	c	c	5	NULL	#	Using where; Using index
 1	SIMPLE	t2	ref	b	b	5	test.t3.c	#	Using where; Using index
 SELECT a, b, c FROM t1 LEFT JOIN (t2, t3) ON b < 3 and b = c;
 a	b	c
@@ -1280,7 +1280,7 @@ DELETE FROM t3;
 EXPLAIN SELECT a, b, c FROM t1 LEFT JOIN (t2, t3) ON b < 3 and b = c;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	index	NULL	a	5	NULL	#	Using index
-1	SIMPLE	t3	index	c	c	5	NULL	#	Using index
+1	SIMPLE	t3	index	c	c	5	NULL	#	Using where; Using index
 1	SIMPLE	t2	ref	b	b	5	test.t3.c	#	Using where; Using index
 SELECT a, b, c FROM t1 LEFT JOIN (t2, t3) ON b < 3 and b = c;
 a	b	c
@@ -1453,7 +1453,7 @@ explain select * from t4 join
 t2 left join (t3 join t5 on t5.a=t3.b) on t3.a=t2.b where t4.a<=>t3.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	X	
-1	SIMPLE	t3	ref	a	a	5	test.t2.b	X	
+1	SIMPLE	t3	ref	a	a	5	test.t2.b	X	Using where
 1	SIMPLE	t5	ref	a	a	5	test.t3.b	X	
 1	SIMPLE	t4	ref	a	a	5	test.t3.b	X	Using where
 explain select * from (t4 join t6 on t6.a=t4.b) right join t3 on t4.a=t3.b
@@ -1461,17 +1461,17 @@ join t2 left join (t5 join t7 on t7.a=t5.b) on t5.a=t2.b where t3.a<=>t2.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	X	
 1	SIMPLE	t3	ref	a	a	5	test.t2.b	X	Using where
-1	SIMPLE	t4	ref	a	a	5	test.t3.b	X	
+1	SIMPLE	t4	ref	a	a	5	test.t3.b	X	Using where
 1	SIMPLE	t6	ref	a	a	5	test.t4.b	X	
-1	SIMPLE	t5	ref	a	a	5	test.t2.b	X	
+1	SIMPLE	t5	ref	a	a	5	test.t2.b	X	Using where
 1	SIMPLE	t7	ref	a	a	5	test.t5.b	X	
 explain select * from t2 left join
 (t3 left join (t4 join t6 on t6.a=t4.b) on t4.a=t3.b 
 join t5 on t5.a=t3.b) on t3.a=t2.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	X	
-1	SIMPLE	t3	ref	a	a	5	test.t2.b	X	
-1	SIMPLE	t4	ref	a	a	5	test.t3.b	X	
+1	SIMPLE	t3	ref	a	a	5	test.t2.b	X	Using where
+1	SIMPLE	t4	ref	a	a	5	test.t3.b	X	Using where
 1	SIMPLE	t6	ref	a	a	5	test.t4.b	X	
 1	SIMPLE	t5	ref	a	a	5	test.t3.b	X	
 drop table t0, t1, t2, t3, t4, t5, t6, t7;
@@ -1486,8 +1486,8 @@ explain select * from t1 left join
 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	10	
-1	SIMPLE	t2	ref	a	a	5	test.t1.a	1	
-1	SIMPLE	t3	ref	a	a	5	test.t2.a	1	
+1	SIMPLE	t2	ref	a	a	5	test.t1.a	1	Using where
+1	SIMPLE	t3	ref	a	a	5	test.t2.a	1	Using where
 drop table t1, t2, t3;
 CREATE TABLE t1 (id int NOT NULL PRIMARY KEY, type varchar(10));
 CREATE TABLE t2 (pid int NOT NULL PRIMARY KEY, type varchar(10));

mysql-test/suite/pbxt/r/join_outer.result

@@ -1126,7 +1126,7 @@ a	b	a	b
 7	8	7	5
 EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a = t2.a OR t1.a = t2.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	ALL	PRIMARY	NULL	NULL	NULL	4	
+1	SIMPLE	t2	ALL	PRIMARY	NULL	NULL	NULL	4	Using where
 1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t2.a	1	
 EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a IN(t2.a, t2.b);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

mysql-test/suite/pbxt/r/null_key.result

@@ -178,12 +178,12 @@ create table t2 (a int);
 insert into t2 values (7),(8);
 explain select * from t2 straight_join t1 where t1.a=t2.a and b is null;
 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 where
 1	SIMPLE	t1	ref	a,b	a	10	test.t2.a,const	2	Using where; Using index
 drop index b on t1;
 explain select * from t2,t1 where t1.a=t2.a and b is null;
 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 where
 1	SIMPLE	t1	ref	a	a	10	test.t2.a,const	2	Using where; Using index
 select * from t2,t1 where t1.a=t2.a and b is null;
 a	a	b
@@ -191,7 +191,7 @@ a	a	b
 8	8	NULL
 explain select * from t2,t1 where t1.a=t2.a and (b= 7 or b is null);
 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 where
 1	SIMPLE	t1	ref_or_null	a	a	10	test.t2.a,const	4	Using index
 select * from t2,t1 where t1.a=t2.a and (b= 7 or b is null);
 a	a	b
@@ -407,8 +407,8 @@ EXPLAIN SELECT SQL_CALC_FOUND_ROWS * FROM t1 LEFT JOIN t2 ON t1.a=t2.a
 LEFT JOIN t3 ON t2.b=t3.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
-1	SIMPLE	t2	ref	idx	idx	5	test.t1.a	1	
-1	SIMPLE	t3	ref	idx	idx	5	test.t2.b	1	Using index
+1	SIMPLE	t2	ref	idx	idx	5	test.t1.a	1	Using where
+1	SIMPLE	t3	ref	idx	idx	5	test.t2.b	1	Using where; Using index
 FLUSH STATUS ;
 SELECT SQL_CALC_FOUND_ROWS * FROM t1 LEFT JOIN t2 ON t1.a=t2.a
 LEFT JOIN t3 ON t2.b=t3.b;
@@ -423,8 +423,8 @@ FOUND_ROWS()
 SHOW STATUS LIKE "handler_read%";
 Variable_name	Value
 Handler_read_first	0
-Handler_read_key	6
-Handler_read_next	2
+Handler_read_key	8
+Handler_read_next	31942
 Handler_read_prev	0
 Handler_read_rnd	0
 Handler_read_rnd_next	5

mysql-test/suite/pbxt/r/select.result

@@ -2368,7 +2368,7 @@ 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	1	
+1	SIMPLE	t2	ref	c,d	d	5	const	1	Using where
 1	SIMPLE	t1	ref	a	a	5	test.t2.c	1	
 select * from t1 left join t2 on a=c where d in (4);
 a	b	c	d
@@ -2376,7 +2376,7 @@ 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	1	
+1	SIMPLE	t2	ref	c,d	d	5	const	1	Using where
 1	SIMPLE	t1	ref	a	a	5	test.t2.c	1	
 select * from t1 left join t2 on a=c where d = 4;
 a	b	c	d
@@ -3632,7 +3632,7 @@ WHERE t1.id = 8 AND (t2.i=t1.b OR t2.i=t1.e) AND t3.a=t2.a AND
 t3.c IN ('bb','ee');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	const	PRIMARY	PRIMARY	4	const	1	
-1	SIMPLE	t2	range	si,ai	si	5	NULL	2	Using where
+1	SIMPLE	t2	range	si,ai	ai	5	NULL	1	Using where
 1	SIMPLE	t3	eq_ref	PRIMARY,ci	PRIMARY	4	test.t2.a	1	Using where
 DROP TABLE t1,t2,t3;
 DROP TABLE IF EXISTS t1;

mysql-test/t/join.test

@@ -851,4 +851,23 @@ ENGINE=MERGE  UNION=(t1,t2);
 SELECT t1.a FROM mm1,t1;
 DROP TABLE t1, t2, mm1;
 
+--echo #
+--echo # BUG#47217 Lost optimization caused slowdown & wrong result.
+--echo #
+CREATE TABLE t1 (pk INT, v VARCHAR(2), PRIMARY KEY(pk));
+CREATE INDEX ix1 ON t1(v);
+CREATE TABLE t2 (pk INT, v VARCHAR(2), PRIMARY KEY(pk));
+CREATE INDEX ix2 ON t2(v);
+INSERT INTO t1 VALUES (1,'a'),(2,NULL);
+INSERT INTO t2 VALUES (1,NULL);
+EXPLAIN SELECT * FROM t1 JOIN t2 ON t1.v = t2.v ORDER BY 1;
+EXPLAIN SELECT * FROM t1 JOIN t2 ON t1.v = t2.v;
+INSERT INTO t1 VALUES (3,'b'),(4,NULL),(5,'c'),(6,'cc'),(7,'d'),
+  (8,'dd'),(9,'e'),(10,'ee');
+INSERT INTO t2 VALUES (2,NULL);
+FLUSH STATUS;
+SELECT * FROM t1 JOIN t2 ON t1.v = t2.v WHERE t2.v IS NULL ORDER BY 1;
+SHOW STATUS LIKE 'Handler_read_%';
+DROP TABLE t1, t2;
+
 --echo End of 5.1 tests

mysql-test/t/join_cache.test

@@ -2026,5 +2026,55 @@ SET join_cache_level=default;
 
 DROP TABLE t1,t2,t3,t4;
 
+--echo #
+--echo # BUG#52636: allowing JOINs on NULL values w/ join_cache_level = 5-8
+--echo #
+
+CREATE TABLE t1 (b int);
+INSERT INTO t1 VALUES (NULL),(3);
+
+CREATE TABLE t2 (a int, b int, KEY (b));
+INSERT INTO t2 VALUES (100,NULL),(150,200);
+
+set join_cache_level = 5;
+explain SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+--sorted_result
+SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+
+set join_cache_level = 8;
+explain SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+--sorted_result
+SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+
+# test crash when no key is worth collecting by BKA for t2's ref
+delete from t1;
+INSERT INTO t1 VALUES (NULL),(NULL);
+set join_cache_level = 5;
+explain SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+--sorted_result
+SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+
+DROP TABLE t1,t2;
+
+# test varchar keys
+CREATE TABLE t1 (b varchar(100));
+INSERT INTO t1 VALUES (NULL),("some varchar");
+
+CREATE TABLE t2 (a int, b varchar(100), KEY (b));
+INSERT INTO t2 VALUES (100,NULL),(150,"varchar"),(200,NULL),(250,"long long varchar");
+
+set join_cache_level = 5;
+explain SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+--sorted_result
+SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+
+set join_cache_level = 8;
+explain SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+--sorted_result
+SELECT t2.a FROM t1 LEFT JOIN t2 ON t2.b  = t1.b;
+
+set join_cache_level = default;
+DROP TABLE t1,t2;
+
 # this must be the last command in the file
 set @@optimizer_switch=@save_optimizer_switch;

sql/sql_select.cc

@@ -6443,6 +6443,8 @@ inline void add_cond_and_fix(Item **e1, Item *e2)
 {
   if (*e1)
   {
+    if (!e2)
+      return;
     Item *res;
     if ((res= new Item_cond_and(*e1, e2)))
     {
@@ -6513,9 +6515,8 @@ static void add_not_null_conds(JOIN *join)
   for (uint i=join->const_tables ; i < join->tables ; i++)
   {
     JOIN_TAB *tab=join->join_tab+i;
-    if ((tab->type == JT_REF || tab->type == JT_EQ_REF || 
-         tab->type == JT_REF_OR_NULL) &&
-        !tab->table->maybe_null)
+    if (tab->type == JT_REF || tab->type == JT_EQ_REF || 
+        tab->type == JT_REF_OR_NULL)
     {
       for (uint keypart= 0; keypart < tab->ref.key_parts; keypart++)
       {
@@ -6547,9 +6548,14 @@ static void add_not_null_conds(JOIN *join)
           DBUG_EXECUTE("where",print_where(notnull,
                                            referred_tab->table->alias,
                                            QT_ORDINARY););
-          COND *new_cond= referred_tab->select_cond;
-          add_cond_and_fix(&new_cond, notnull);
-          referred_tab->set_select_cond(new_cond, __LINE__);
+          if (!tab->first_inner)
+	  {
+            COND *new_cond= referred_tab->select_cond;
+            add_cond_and_fix(&new_cond, notnull);
+            referred_tab->set_select_cond(new_cond, __LINE__);
+          }
+          else
+            add_cond_and_fix(tab->first_inner->on_expr_ref, notnull);
         }
       }
     }
@@ -6729,6 +6735,10 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
 	  make_cond_for_table(cond,
                               join->const_table_map,
                               (table_map) 0, TRUE);
+        /* Add conditions added by add_not_null_conds(). */
+        for (uint i= 0 ; i < join->const_tables ; i++)
+          add_cond_and_fix(&const_cond, join->join_tab[i].select_cond);
+
         DBUG_EXECUTE("where",print_where(const_cond,"constants", QT_ORDINARY););
         for (JOIN_TAB *tab= join->join_tab+join->const_tables;
              tab < join->join_tab+join->tables ; tab++)
@@ -6827,6 +6837,9 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
       tmp= NULL;
       if (cond)
         tmp= make_cond_for_table(cond, used_tables, current_map, FALSE);
+      /* Add conditions added by add_not_null_conds(). */
+      if (tab->select_cond)
+        add_cond_and_fix(&tmp, tab->select_cond);
       if (cond && !tmp && tab->quick)
       {						// Outer join
         if (tab->type != JT_ALL)
@@ -13898,13 +13911,6 @@ join_read_always_key(JOIN_TAB *tab)
     }
   }
 
-  /* Perform "Late NULLs Filtering" (see internals manual for explanations) */
-  for (uint i= 0 ; i < tab->ref.key_parts ; i++)
-  {
-    if ((tab->ref.null_rejecting & 1 << i) && tab->ref.items[i]->is_null())
-        return -1;
-  }
-
   if (cp_buffer_from_ref(tab->join->thd, table, &tab->ref))
     return -1;
   if ((error= table->file->ha_index_read_map(table->record[0],