MWL#90: Subqueries: Inside-out execution for non-semijoin materialized

  subqueries that are AND-parts of the WHERE
- First code (needs cleanup).

mysql-test/include/mix1.inc

@@ -1522,6 +1522,12 @@ INSERT INTO t1 VALUES (1,1,1), (1,1,1), (1,1,2), (1,1,1), (1,1,2);
 
 SELECT 1 FROM (SELECT COUNT(DISTINCT c1) 
                  FROM t1 WHERE c2 IN (1, 1) AND c3 = 2 GROUP BY c2) x;
+--echo # MariaDB note:
+--echo #  This will show 2 for table which has 5 rows. 
+--echo #  This is because the access method employed is actually range access
+--echo #  which scans 2 records (yes, EXPLAIN displays it incorrectly).
+--echo #  our correct printing is an artifact of changing in select_describe()
+--echo #  from printing table->starts.records() to tab->records.
 EXPLAIN 
 SELECT 1 FROM (SELECT COUNT(DISTINCT c1) 
                  FROM t1 WHERE c2 IN (1, 1) AND c3 = 2 GROUP BY c2) x;
@@ -1535,6 +1541,7 @@ INSERT INTO t1 VALUES (1,1,1), (1,1,1), (1,1,2), (1,1,1), (1,1,2);
 
 SELECT 1 FROM (SELECT COUNT(DISTINCT c1) 
                  FROM t1 WHERE c2 IN (1, 1) AND c3 = 2 GROUP BY c2) x;
+--echo # See above "MariaDB note"
 EXPLAIN 
 SELECT 1 FROM (SELECT COUNT(DISTINCT c1) 
                  FROM t1 WHERE c2 IN (1, 1) AND c3 = 2 GROUP BY c2) x;
@@ -1549,6 +1556,7 @@ INSERT INTO t1 VALUES (1,1,1), (1,1,1), (1,1,2), (1,1,1), (1,1,2);
 
 SELECT 1 FROM (SELECT COUNT(DISTINCT c1) 
                  FROM t1 WHERE c2 IN (1, 1) AND c3 = 2 GROUP BY c2) x;
+--echo # See above "MariaDB note"
 EXPLAIN 
 SELECT 1 FROM (SELECT COUNT(DISTINCT c1) 
                  FROM t1 WHERE c2 IN (1, 1) AND c3 = 2 GROUP BY c2) x;

mysql-test/r/group_min_max.result

@@ -2255,7 +2255,8 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 EXPLAIN SELECT 1 FROM t1 AS t1_outer WHERE 
 a IN (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t1_outer	index	NULL	a	10	NULL	15	Using where; Using index
+1	PRIMARY	SUBQUERY#2	ALL	NULL	NULL	NULL	NULL	8	
+1	PRIMARY	t1_outer	ref	a	a	5	materialized subselect.max(b)	2	Using index
 2	SUBQUERY	t1	range	NULL	a	5	NULL	8	Using index for group-by
 EXPLAIN SELECT 1 FROM t1 AS t1_outer GROUP BY a HAVING 
 a > (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2);

mysql-test/r/having.result

@@ -249,10 +249,10 @@ where t1.col2 in
 group by t2.col1, t2.col2 having t2.col1 <= 10);
 col1
 10
-20
-30
 10
 10
+20
+30
 10
 select t1.col1 from t1
 where t1.col2 in 
@@ -262,10 +262,10 @@ having t2.col1 <=
 (select min(t3.col1) from t3));
 col1
 10
-20
-30
 10
 10
+20
+30
 10
 select t1.col1 from t1
 where t1.col2 in

mysql-test/r/innodb_mysql.result

@@ -1727,12 +1727,18 @@ SELECT 1 FROM (SELECT COUNT(DISTINCT c1)
 FROM t1 WHERE c2 IN (1, 1) AND c3 = 2 GROUP BY c2) x;
 1
 1
+# MariaDB note:
+#  This will show 2 for table which has 5 rows. 
+#  This is because the access method employed is actually range access
+#  which scans 2 records (yes, EXPLAIN displays it incorrectly).
+#  our correct printing is an artifact of changing in select_describe()
+#  from printing table->starts.records() to tab->records.
 EXPLAIN 
 SELECT 1 FROM (SELECT COUNT(DISTINCT c1) 
 FROM t1 WHERE c2 IN (1, 1) AND c3 = 2 GROUP BY c2) x;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	<derived2>	system	NULL	NULL	NULL	NULL	1	
-2	DERIVED	t1	index	c3,c2	c2	10	NULL	5	
+2	DERIVED	t1	index	c3,c2	c2	10	NULL	2	
 DROP TABLE t1;
 CREATE TABLE t1 (c1 REAL, c2 REAL, c3 REAL, KEY (c3), KEY (c2, c3))
 ENGINE=InnoDB;
@@ -1741,12 +1747,13 @@ SELECT 1 FROM (SELECT COUNT(DISTINCT c1)
 FROM t1 WHERE c2 IN (1, 1) AND c3 = 2 GROUP BY c2) x;
 1
 1
+# See above "MariaDB note"
 EXPLAIN 
 SELECT 1 FROM (SELECT COUNT(DISTINCT c1) 
 FROM t1 WHERE c2 IN (1, 1) AND c3 = 2 GROUP BY c2) x;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	<derived2>	system	NULL	NULL	NULL	NULL	1	
-2	DERIVED	t1	index	c3,c2	c2	18	NULL	5	
+2	DERIVED	t1	index	c3,c2	c2	18	NULL	2	
 DROP TABLE t1;
 CREATE TABLE t1 (c1 DECIMAL(12,2), c2 DECIMAL(12,2), c3 DECIMAL(12,2), 
 KEY (c3), KEY (c2, c3))
@@ -1756,12 +1763,13 @@ SELECT 1 FROM (SELECT COUNT(DISTINCT c1)
 FROM t1 WHERE c2 IN (1, 1) AND c3 = 2 GROUP BY c2) x;
 1
 1
+# See above "MariaDB note"
 EXPLAIN 
 SELECT 1 FROM (SELECT COUNT(DISTINCT c1) 
 FROM t1 WHERE c2 IN (1, 1) AND c3 = 2 GROUP BY c2) x;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	<derived2>	system	NULL	NULL	NULL	NULL	1	
-2	DERIVED	t1	index	c3,c2	c2	14	NULL	5	
+2	DERIVED	t1	index	c3,c2	c2	14	NULL	2	
 DROP TABLE t1;
 End of 5.1 tests
 drop table if exists t1, t2, t3;

mysql-test/r/partition.result

@@ -1382,7 +1382,7 @@ NULL
 2
 explain partitions select * from t1 where a is null or a < 0 or a > 1;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	pn,p2	ALL	NULL	NULL	NULL	NULL	4	Using where
+1	SIMPLE	t1	pn,p2	ALL	NULL	NULL	NULL	NULL	2	Using where
 drop table t1;
 CREATE TABLE t1 (id INT NOT NULL PRIMARY KEY, name VARCHAR(20)) 
 ENGINE=MyISAM DEFAULT CHARSET=latin1

mysql-test/r/partition_hash.result

@@ -69,25 +69,25 @@ id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	p0,p1,p2,p3	ALL	NULL	NULL	NULL	NULL	9	Using where
 explain partitions select * from t1 where a is null or (a >= 5 and a <= 7);
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0,p2,p3	ALL	NULL	NULL	NULL	NULL	9	Using where
+1	SIMPLE	t1	p0,p2,p3	ALL	NULL	NULL	NULL	NULL	7	Using where
 explain partitions select * from t1 where a is null;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	9	Using where
+1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	3	Using where
 explain partitions select * from t1 where a is not null;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	p0,p1,p2,p3	ALL	NULL	NULL	NULL	NULL	9	Using where
 explain partitions select * from t1 where a >= 1 and a < 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0,p1	ALL	NULL	NULL	NULL	NULL	9	Using where
+1	SIMPLE	t1	p0,p1	ALL	NULL	NULL	NULL	NULL	5	Using where
 explain partitions select * from t1 where a >= 3 and a <= 5;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p1,p2	ALL	NULL	NULL	NULL	NULL	9	Using where
+1	SIMPLE	t1	p1,p2	ALL	NULL	NULL	NULL	NULL	4	Using where
 explain partitions select * from t1 where a > 2 and a < 4;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p1	ALL	NULL	NULL	NULL	NULL	9	Using where
+1	SIMPLE	t1	p1	ALL	NULL	NULL	NULL	NULL	2	Using where
 explain partitions select * from t1 where a > 3 and a <= 6;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p2,p3	ALL	NULL	NULL	NULL	NULL	9	Using where
+1	SIMPLE	t1	p2,p3	ALL	NULL	NULL	NULL	NULL	4	Using where
 explain partitions select * from t1 where a > 5;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	p0,p1,p2,p3	ALL	NULL	NULL	NULL	NULL	9	Using where

mysql-test/r/partition_range.result

@@ -59,13 +59,13 @@ id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	pnull	system	NULL	NULL	NULL	NULL	1	
 explain partitions select * from t1 where a >= 0;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0,p1	ALL	NULL	NULL	NULL	NULL	3	Using where
+1	SIMPLE	t1	p0,p1	ALL	NULL	NULL	NULL	NULL	2	Using where
 explain partitions select * from t1 where a < 0;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables
 explain partitions select * from t1 where a <= 0;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	pnull,p0	ALL	NULL	NULL	NULL	NULL	3	Using where
+1	SIMPLE	t1	pnull,p0	ALL	NULL	NULL	NULL	NULL	2	Using where
 explain partitions select * from t1 where a > 1;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables
@@ -98,16 +98,16 @@ select * from t1 where a > 1;
 a	b
 explain partitions select * from t1 where a is null;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	pnull_pnullsp0,pnull_pnullsp1	ALL	NULL	NULL	NULL	NULL	6	Using where
+1	SIMPLE	t1	pnull_pnullsp0,pnull_pnullsp1	ALL	NULL	NULL	NULL	NULL	2	Using where
 explain partitions select * from t1 where a >= 0;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0_p0sp0,p0_p0sp1,p1_p1sp0,p1_p1sp1	ALL	NULL	NULL	NULL	NULL	6	Using where
+1	SIMPLE	t1	p0_p0sp0,p0_p0sp1,p1_p1sp0,p1_p1sp1	ALL	NULL	NULL	NULL	NULL	4	Using where
 explain partitions select * from t1 where a < 0;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	pnull_pnullsp0,pnull_pnullsp1	ALL	NULL	NULL	NULL	NULL	6	Using where
+1	SIMPLE	t1	pnull_pnullsp0,pnull_pnullsp1	ALL	NULL	NULL	NULL	NULL	2	Using where
 explain partitions select * from t1 where a <= 0;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	pnull_pnullsp0,pnull_pnullsp1,p0_p0sp0,p0_p0sp1	ALL	NULL	NULL	NULL	NULL	6	Using where
+1	SIMPLE	t1	pnull_pnullsp0,pnull_pnullsp1,p0_p0sp0,p0_p0sp1	ALL	NULL	NULL	NULL	NULL	4	Using where
 explain partitions select * from t1 where a > 1;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables

mysql-test/r/subselect.result

@@ -3417,7 +3417,8 @@ AAA	8
 EXPLAIN
 SELECT * FROM t1 WHERE (a,b) = ANY (SELECT a, max(b) FROM t1 GROUP BY a);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	9	Using where
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	9	
+1	PRIMARY	SUBQUERY#2	eq_ref	distinct_key	distinct_key	23	test.t1.a,test.t1.b	1	
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	9	Using temporary; Using filesort
 ALTER TABLE t1 ADD INDEX(a);
 SELECT * FROM t1 WHERE (a,b) = ANY (SELECT a, max(b) FROM t1 GROUP BY a);
@@ -3428,7 +3429,8 @@ AAA	8
 EXPLAIN
 SELECT * FROM t1 WHERE (a,b) = ANY (SELECT a, max(b) FROM t1 GROUP BY a);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	9	Using where
+1	PRIMARY	t1	ALL	a	NULL	NULL	NULL	9	
+1	PRIMARY	SUBQUERY#2	eq_ref	distinct_key	distinct_key	23	test.t1.a,test.t1.b	1	
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	9	Using temporary; Using filesort
 DROP TABLE t1;
 create table t1( f1 int,f2 int);
@@ -4322,16 +4324,18 @@ CREATE TABLE t1 (a INT);
 INSERT INTO t1 VALUES (1),(2);
 EXPLAIN EXTENDED SELECT 1 FROM t1 WHERE 1 IN (SELECT 1 FROM t1 GROUP BY a);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	
+1	PRIMARY	SUBQUERY#2	const	distinct_key	distinct_key	4	const	1	100.00	
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using temporary; Using filesort
 Warnings:
-Note	1003	select 1 AS `1` from `test`.`t1` where <in_optimizer>(1,1 in ( <materialize> (select 1 AS `1` from `test`.`t1` group by `test`.`t1`.`a` ), <primary_index_lookup>(1 in <temporary table> on distinct_key where ((1 = `materialized subselect`.`1`)))))
+Note	1003	select 1 AS `1` from  <materialize> (select 1 AS `1` from `test`.`t1` group by `test`.`t1`.`a`) join `test`.`t1` where (`materialized subselect`.`1` = 1)
 EXPLAIN EXTENDED SELECT 1 FROM t1 WHERE 1 IN (SELECT 1 FROM t1 WHERE a > 3 GROUP BY a);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
-1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	
+1	PRIMARY	SUBQUERY#2	const	distinct_key	distinct_key	4	const	1	100.00	
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where; Using temporary; Using filesort
 Warnings:
-Note	1003	select 1 AS `1` from `test`.`t1` where <in_optimizer>(1,1 in ( <materialize> (select 1 AS `1` from `test`.`t1` where (`test`.`t1`.`a` > 3) group by `test`.`t1`.`a` ), <primary_index_lookup>(1 in <temporary table> on distinct_key where ((1 = `materialized subselect`.`1`)))))
+Note	1003	select 1 AS `1` from  <materialize> (select 1 AS `1` from `test`.`t1` where (`test`.`t1`.`a` > 3) group by `test`.`t1`.`a`) join `test`.`t1` where (`materialized subselect`.`1` = 1)
 DROP TABLE t1;
 #
 # Bug#45061: Incorrectly market field caused wrong result.

mysql-test/r/subselect3.result

@@ -1212,24 +1212,28 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	10	Using where
 explain select straight_join * from t1 A, t1 B where A.a in (select a from t2);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	A	ALL	NULL	NULL	NULL	NULL	10	Using where
+1	PRIMARY	A	ALL	NULL	NULL	NULL	NULL	10	
 1	PRIMARY	B	ALL	NULL	NULL	NULL	NULL	10	Using join buffer
+1	PRIMARY	SUBQUERY#2	eq_ref	distinct_key	distinct_key	5	test.A.a	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	10	
 explain select * from t2 where a in (select straight_join A.a from t1 A, t1 B);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	10	Using where
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	10	
+1	PRIMARY	SUBQUERY#2	eq_ref	distinct_key	distinct_key	5	test.t2.a	1	
 2	SUBQUERY	A	ALL	NULL	NULL	NULL	NULL	10	
 2	SUBQUERY	B	ALL	NULL	NULL	NULL	NULL	10	Using join buffer
 explain select * from t2 where a in (select straight_join A.a from t1 A, t1 B);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	10	Using where
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	10	
+1	PRIMARY	SUBQUERY#2	eq_ref	distinct_key	distinct_key	5	test.t2.a	1	
 2	SUBQUERY	A	ALL	NULL	NULL	NULL	NULL	10	
 2	SUBQUERY	B	ALL	NULL	NULL	NULL	NULL	10	Using join buffer
 explain select straight_join * from t2 X, t2 Y 
 where X.a in (select straight_join A.a from t1 A, t1 B);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	X	ALL	NULL	NULL	NULL	NULL	10	Using where
+1	PRIMARY	X	ALL	NULL	NULL	NULL	NULL	10	
 1	PRIMARY	Y	ALL	NULL	NULL	NULL	NULL	10	Using join buffer
+1	PRIMARY	SUBQUERY#2	eq_ref	distinct_key	distinct_key	5	test.X.a	1	
 2	SUBQUERY	A	ALL	NULL	NULL	NULL	NULL	10	
 2	SUBQUERY	B	ALL	NULL	NULL	NULL	NULL	10	Using join buffer
 create table t0 (a int, b int);

mysql-test/r/subselect3_jcl6.result

@@ -1217,24 +1217,28 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	10	Using where
 explain select straight_join * from t1 A, t1 B where A.a in (select a from t2);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	A	ALL	NULL	NULL	NULL	NULL	10	Using where
+1	PRIMARY	A	ALL	NULL	NULL	NULL	NULL	10	
 1	PRIMARY	B	ALL	NULL	NULL	NULL	NULL	10	Using join buffer
+1	PRIMARY	SUBQUERY#2	eq_ref	distinct_key	distinct_key	5	test.A.a	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	10	
 explain select * from t2 where a in (select straight_join A.a from t1 A, t1 B);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	10	Using where
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	10	
+1	PRIMARY	SUBQUERY#2	eq_ref	distinct_key	distinct_key	5	test.t2.a	1	
 2	SUBQUERY	A	ALL	NULL	NULL	NULL	NULL	10	
 2	SUBQUERY	B	ALL	NULL	NULL	NULL	NULL	10	Using join buffer
 explain select * from t2 where a in (select straight_join A.a from t1 A, t1 B);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	10	Using where
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	10	
+1	PRIMARY	SUBQUERY#2	eq_ref	distinct_key	distinct_key	5	test.t2.a	1	
 2	SUBQUERY	A	ALL	NULL	NULL	NULL	NULL	10	
 2	SUBQUERY	B	ALL	NULL	NULL	NULL	NULL	10	Using join buffer
 explain select straight_join * from t2 X, t2 Y 
 where X.a in (select straight_join A.a from t1 A, t1 B);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	X	ALL	NULL	NULL	NULL	NULL	10	Using where
+1	PRIMARY	X	ALL	NULL	NULL	NULL	NULL	10	
 1	PRIMARY	Y	ALL	NULL	NULL	NULL	NULL	10	Using join buffer
+1	PRIMARY	SUBQUERY#2	eq_ref	distinct_key	distinct_key	5	test.X.a	1	
 2	SUBQUERY	A	ALL	NULL	NULL	NULL	NULL	10	
 2	SUBQUERY	B	ALL	NULL	NULL	NULL	NULL	10	Using join buffer
 create table t0 (a int, b int);

mysql-test/suite/parts/r/partition_alter3_innodb.result

@@ -141,7 +141,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	part1	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	part1	ALL	NULL	NULL	NULL	NULL	7	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -165,7 +165,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	5	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -190,7 +190,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	3	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -226,7 +226,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p6	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p6	ALL	NULL	NULL	NULL	NULL	3	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -248,7 +248,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p4	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p4	ALL	NULL	NULL	NULL	NULL	4	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -269,7 +269,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	4	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -289,7 +289,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	5	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -308,7 +308,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	part1	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	part1	ALL	NULL	NULL	NULL	NULL	7	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -326,7 +326,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	10	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -452,7 +452,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	7	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -476,7 +476,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	5	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -504,7 +504,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p6	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p6	ALL	NULL	NULL	NULL	NULL	3	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -538,7 +538,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	4	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -563,7 +563,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	3	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -587,7 +587,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p4	ALL	NULL	NULL	NULL	NULL	23	Using where
+1	SIMPLE	t1	p4	ALL	NULL	NULL	NULL	NULL	10	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -610,7 +610,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	5	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -632,7 +632,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	7	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -653,7 +653,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	10	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1

mysql-test/suite/parts/r/partition_alter3_myisam.result

@@ -155,7 +155,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	part1	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	part1	ALL	NULL	NULL	NULL	NULL	7	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -187,7 +187,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	5	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -228,7 +228,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	3	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -278,7 +278,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p6	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p6	ALL	NULL	NULL	NULL	NULL	3	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -312,7 +312,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p4	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p4	ALL	NULL	NULL	NULL	NULL	4	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -343,7 +343,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	4	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -371,7 +371,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	5	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -396,7 +396,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	part1	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	part1	ALL	NULL	NULL	NULL	NULL	7	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -418,7 +418,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) FROM t1 WHERE f_date = '1000-02-10';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	10	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -552,7 +552,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	7	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -584,7 +584,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	5	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -628,7 +628,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p6	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p6	ALL	NULL	NULL	NULL	NULL	3	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -676,7 +676,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	4	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -713,7 +713,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	3	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -747,7 +747,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p4	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p4	ALL	NULL	NULL	NULL	NULL	10	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -778,7 +778,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	5	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -806,7 +806,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	part7	ALL	NULL	NULL	NULL	NULL	7	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1
@@ -831,7 +831,7 @@ t1.frm
 t1.par
 EXPLAIN PARTITIONS SELECT COUNT(*) <> 1 FROM t1 WHERE f_int1 = 3;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	20	Using where
+1	SIMPLE	t1	p0	ALL	NULL	NULL	NULL	NULL	10	Using where
 # check read single success: 1
 # check read all success: 1
 # check read row by row success: 1

mysql-test/t/subselect_mat.test

@@ -829,8 +829,12 @@ select min(a1) from t1 where 7 in (select b1 from t2);
 # This is the only correct result of all four queries. This difference is
 # filed as BUG#40037.
 set @@optimizer_switch='default,materialization=off';
+-- echo # with MariaDB and MWL#90, this particular case is solved:
 explain select min(a1) from t1 where 7 in (select b1 from t2);
 select min(a1) from t1 where 7 in (select b1 from t2);
+-- echo # but when we go around MWL#90 code, the problem still shows up:
+explain select min(a1) from t1 where 7 in (select b1 from t2) or 2> 4;
+select min(a1) from t1 where 7 in (select b1 from t2) or 2> 4;
 drop table t1,t2;
 
 #

sql/item_subselect.cc

@@ -468,6 +468,12 @@ bool Item_subselect::exec()
   return (res);
 }
 
+int Item_subselect::optimize()
+{
+  int res;
+  res= engine->optimize();
+  return res;
+}
 
 /*
   Compute the IN predicate if the left operand's cache changed.
@@ -2088,7 +2094,7 @@ void Item_in_subselect::update_used_tables()
     @retval FALSE an execution method was chosen successfully
 */
 
-bool Item_in_subselect::setup_engine()
+bool Item_in_subselect::setup_engine(bool dont_switch_arena)
 {
   subselect_hash_sj_engine *new_engine= NULL;
   bool res= FALSE;
@@ -2103,7 +2109,7 @@ bool Item_in_subselect::setup_engine()
 
     old_engine= (subselect_single_select_engine*) engine;
 
-    if (arena->is_conventional())
+    if (arena->is_conventional() || dont_switch_arena)
       arena= 0;
     else
       thd->set_n_backup_active_arena(arena, &backup);
@@ -3457,7 +3463,7 @@ subselect_hash_sj_engine::get_strategy_using_schema()
         bitmap_set_bit(&partial_match_key_parts, i);
         ++count_partial_match_columns;
       }
-    }
+    };
   }
 
   /* If no column contains NULLs use regular hash index lookups. */
@@ -3970,6 +3976,17 @@ void subselect_hash_sj_engine::cleanup()
 }
 
 
+int subselect_hash_sj_engine::optimize()
+{
+  int res= 0;
+  SELECT_LEX *save_select= thd->lex->current_select;
+  thd->lex->current_select= materialize_join->select_lex;
+  res= materialize_join->optimize();
+  thd->lex->current_select= save_select;
+
+  return res;
+}
+
 /**
   Execute a subquery IN predicate via materialization.
 

sql/item_subselect.h

@@ -52,9 +52,9 @@ public:
 public:
   /* unit of subquery */
   st_select_lex_unit *unit;
-protected:
   /* engine that perform execution of subselect (single select or union) */
   subselect_engine *engine;
+protected:
   /* old engine if engine was changed */
   subselect_engine *old_engine;
   /* cache of used external tables */
@@ -139,6 +139,7 @@ public:
   bool mark_as_dependent(THD *thd, st_select_lex *select, Item *item);
   void fix_after_pullout(st_select_lex *new_parent, Item **ref);
   void recalc_used_tables(st_select_lex *new_parent, bool after_pullout);
+  virtual int optimize();
   virtual bool exec();
   virtual void fix_length_and_dec();
   table_map used_tables() const;
@@ -333,7 +334,9 @@ protected:
     all JOIN in UNION
   */
   Item *expr;
+public:
   Item_in_optimizer *optimizer;
+protected:
   bool was_null;
   bool abort_on_null;
 public:
@@ -379,6 +382,10 @@ public:
   };
   enum_exec_method exec_method;
 
+  /* JTBM: temporary measure to tell JTBM predicates from SJ predicates */
+  bool convert_to_semi_join;
+  double startup_cost;
+
   bool *get_cond_guard(int i)
   {
     return pushed_cond_guards ? pushed_cond_guards + i : NULL;
@@ -428,7 +435,7 @@ public:
   bool fix_fields(THD *thd, Item **ref);
   void fix_after_pullout(st_select_lex *new_parent, Item **ref);
   void update_used_tables();
-  bool setup_engine();
+  bool setup_engine(bool dont_switch_arena);
   bool init_left_expr_cache();
   /* Inform 'this' that it was computed, and contains a valid result. */
   void set_first_execution() { if (first_execution) first_execution= FALSE; }
@@ -502,6 +509,7 @@ public:
   THD * get_thd() { return thd; }
   virtual int prepare()= 0;
   virtual void fix_length_and_dec(Item_cache** row)= 0;
+  virtual int optimize() { DBUG_ASSERT(0); return 0; }
   /*
     Execute the engine
 
@@ -734,7 +742,7 @@ inline bool Item_subselect::is_uncacheable() const
 
 class subselect_hash_sj_engine : public subselect_engine
 {
-protected:
+public:
   /* The table into which the subquery is materialized. */
   TABLE *tmp_table;
   /* TRUE if the subquery was materialized into a temp table. */
@@ -746,14 +754,16 @@ protected:
     of subselect_single_select_engine::[prepare | cols].
   */
   subselect_single_select_engine *materialize_engine;
+protected:
   /* The engine used to compute the IN predicate. */
   subselect_engine *lookup_engine;
   /*
     QEP to execute the subquery and materialize its result into a
     temporary table. Created during the first call to exec().
   */
+public:
   JOIN *materialize_join;
-
+protected:
   /* Keyparts of the only non-NULL composite index in a rowid merge. */
   MY_BITMAP non_null_key_parts;
   /* Keyparts of the single column indexes with NULL, one keypart per index. */
@@ -766,7 +776,9 @@ protected:
     IN results because index lookups sometimes match values that are actually
     not equal to the search key in SQL terms.
  */
+public:
   Item_cond_and *semi_join_conds;
+protected:
   /* Possible execution strategies that can be used to compute hash semi-join.*/
   enum exec_strategy {
     UNDEFINED,
@@ -806,6 +818,7 @@ public:
   bool init_runtime();
   void cleanup();
   int prepare() { return 0; } /* Override virtual function in base class. */
+  int optimize();
   int exec();
   virtual void print(String *str, enum_query_type query_type);
   uint cols()

sql/opt_range.cc

@@ -2285,7 +2285,7 @@ int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use,
   quick=0;
   needed_reg.clear_all();
   quick_keys.clear_all();
-  if (keys_to_use.is_clear_all())
+  if (keys_to_use.is_clear_all() || head->pos_in_table_list->jtbm_subselect)
     DBUG_RETURN(0);
   records= head->file->stats.records;
   if (!records)

sql/sql_base.cc

@@ -7661,6 +7661,17 @@ bool setup_tables(THD *thd, Name_resolution_context *context,
       if (res)
         DBUG_RETURN(1);
     }
+    if (table_list->jtbm_subselect)
+    {
+      Item *item= table_list->jtbm_subselect;
+      if (item->fix_fields(thd, &item))
+      {
+        my_error(ER_TOO_MANY_TABLES,MYF(0),MAX_TABLES);
+        DBUG_RETURN(1);
+      }
+      DBUG_ASSERT(item == table_list->jtbm_subselect);
+      table_list->jtbm_subselect->setup_engine(FALSE);
+    }
   }
 
   /* Precompute and store the row types of NATURAL/USING joins. */

sql/sql_join_cache.cc

@@ -33,6 +33,7 @@
 
 #define NO_MORE_RECORDS_IN_BUFFER  (uint)(-1)
 
+int do_jtbm_materialization_if_needed(JOIN_TAB *tab);
 
 /*****************************************************************************
  *  Join cache module
@@ -1778,6 +1779,10 @@ enum_nested_loop_state JOIN_CACHE_BNL::join_matching_records(bool skip_last)
   }
 
   /* Start retrieving all records of the joined table */
+  
+  //jtbm-todo: error handling!
+  do_jtbm_materialization_if_needed(join_tab);
+
   if ((error= join_init_read_record(join_tab))) 
   {
     rc= error < 0 ? NESTED_LOOP_NO_MORE_ROWS: NESTED_LOOP_ERROR;

sql/sql_select.h

@@ -1551,7 +1551,18 @@ public:
   bool union_part; ///< this subselect is part of union 
   bool optimized; ///< flag to avoid double optimization in EXPLAIN
 
+  /* 
+    Subqueries that will need to be converted to semi-join nests (the list 
+    is emptied when conversion is done
+  */
   Array<Item_in_subselect> sj_subselects;
+  
+  /*
+    Subqueries that will need to be converted to JOIN_TABs
+    (Note this is different from the above in the respect that it's part 
+    of WHERE clause or something like that?)
+  */
+  //Array<Item_in_subselect> jtbm_subselects;
 
   /* Temporary tables used to weed-out semi-join duplicates */
   List<TABLE> sj_tmp_tables;
@@ -1575,6 +1586,7 @@ public:
   JOIN(THD *thd_arg, List<Item> &fields_arg, ulonglong select_options_arg,
        select_result *result_arg)
     :fields_list(fields_arg), sj_subselects(thd_arg->mem_root, 4)
+     //jtbm_subselects(thd_arg->mem_root, 4)
   {
     init(thd_arg, fields_arg, select_options_arg, result_arg);
   }

sql/table.h

@@ -1194,6 +1194,7 @@ struct TABLE_LIST
   /* Number of IN-compared expressions */
   uint          sj_in_exprs; 
   Item_in_subselect  *sj_subq_pred;
+  Item_in_subselect  *jtbm_subselect;
   SJ_MATERIALIZATION_INFO *sj_mat_info;
 
   /*