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

- Merge with 5.3 (3)

mysql-test/include/mix1.inc

@@ -1532,6 +1532,12 @@ 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;
@@ -1545,6 +1551,7 @@ 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;
@@ -1559,6 +1566,7 @@ 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_by.result

@@ -1543,7 +1543,7 @@ EXPLAIN SELECT 1 FROM t1 WHERE a IN
 (SELECT a FROM t1 USE INDEX (i2) IGNORE INDEX (i2));
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	index	PRIMARY,i2	PRIMARY	4	NULL	144	Using index
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	4	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	4	func	1	
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	144	
 CREATE TABLE t2 (a INT, b INT, KEY(a));
 INSERT INTO t2 VALUES (1, 1), (2, 2), (3,3), (4,4);

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	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	8	Using where
+1	PRIMARY	t1_outer	ref	a	a	5	<subquery2>.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/metadata.result

@@ -55,7 +55,7 @@ id	data	data
 2	female	no
 select t1.id from t1 union select t2.id from t2;
 Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
-def				id	id	1	4	1	Y	32768	0	63
+def				id	id	1	4	1	Y	49152	0	63
 id
 1
 2
@@ -66,7 +66,7 @@ insert into t1 values (2,'two');
 set @arg00=1 ;
 select @arg00 FROM t1 where a=1 union distinct select 1 FROM t1 where a=1;
 Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
-def				@arg00	@arg00	8	20	1	Y	32768	0	63
+def				@arg00	@arg00	8	20	1	Y	49152	0	63
 @arg00
 1
 select * from (select @arg00) aaa;
@@ -76,7 +76,7 @@ def			aaa	@arg00	@arg00	8	20	1	Y	32768	0	63
 1
 select 1 union select 1;
 Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
-def				1	1	8	20	1	N	32769	0	63
+def				1	1	8	20	1	N	49153	0	63
 1
 1
 select * from (select 1 union select 1) aaa;

mysql-test/r/subselect.result

@@ -1361,7 +1361,7 @@ explain extended select * from t2 where t2.a in (select t1.a from t1,t3 where 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 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)
+1	PRIMARY	t1	ref	a	a	10	test.t2.a,test.t3.a	116	100.00	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`))
 insert into t1 values (3,31);
@@ -2831,7 +2831,7 @@ Note	1003	select `test`.`t1`.`one` AS `one`,`test`.`t1`.`two` AS `two`,<expr_cac
 explain extended SELECT one,two from t1 where ROW(one,two) IN (SELECT one,two FROM t2 WHERE flag = 'N');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	8	100.00	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	10	func	1	1.00	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	10	func,func	1	100.00	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	9	100.00	Using where
 Warnings:
 Note	1003	select `test`.`t1`.`one` AS `one`,`test`.`t1`.`two` AS `two` from `test`.`t1` semi join (`test`.`t2`) where ((`test`.`t2`.`flag` = 'N'))
@@ -3420,6 +3420,7 @@ 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	<subquery2>	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);
@@ -3430,7 +3431,8 @@ 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	Using where
+1	PRIMARY	<subquery2>	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);
@@ -4320,16 +4322,18 @@ 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	<subquery2>	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 <expr_cache><1>(<in_optimizer>(1,1 in ( <materialize> (select 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 from `test`.`t1` group by `test`.`t1`.`a`) join `test`.`t1` where (`<subquery2>`.`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	<subquery2>	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 <expr_cache><1>(<in_optimizer>(1,1 in ( <materialize> (select 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 from `test`.`t1` where (`test`.`t1`.`a` > 3) group by `test`.`t1`.`a`) join `test`.`t1` where (`<subquery2>`.`1` = 1)
 DROP TABLE t1;
 #
 # Bug#45061: Incorrectly market field caused wrong result.
@@ -5002,7 +5006,7 @@ WHERE (ot1.a,ot4.a) IN (SELECT it2.a,it3.a
 FROM it2,it3);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	ot1	ALL	NULL	NULL	NULL	NULL	2	
-1	PRIMARY	subselect2	ALL	unique_key	NULL	NULL	NULL	24	
+1	PRIMARY	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	24	Using where
 1	PRIMARY	ot4	ALL	NULL	NULL	NULL	NULL	8	Using where; Using join buffer (flat, BNL join)
 2	SUBQUERY	it2	ALL	NULL	NULL	NULL	NULL	4	
 2	SUBQUERY	it3	ALL	NULL	NULL	NULL	NULL	6	Using join buffer (flat, BNL join)

mysql-test/r/subselect4.result

@@ -345,7 +345,7 @@ FROM t2
 WHERE PTYPE = 'Design'));
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	t1_IDX	NULL	NULL	NULL	5	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 PREPARE stmt FROM "EXPLAIN SELECT EMPNAME
@@ -360,13 +360,13 @@ WHERE EMPNUM IN
 EXECUTE stmt;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	t1_IDX	NULL	NULL	NULL	5	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 EXECUTE stmt;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	t1_IDX	NULL	NULL	NULL	5	
-1	SIMPLE	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	SIMPLE	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 DEALLOCATE PREPARE stmt;
@@ -383,7 +383,7 @@ FROM t2
 WHERE PTYPE = 'Design'));
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	t1_IDX	NULL	NULL	NULL	5	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 PREPARE stmt FROM "EXPLAIN SELECT EMPNAME
@@ -398,13 +398,13 @@ WHERE EMPNUM IN
 EXECUTE stmt;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	t1_IDX	NULL	NULL	NULL	5	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 EXECUTE stmt;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	t1_IDX	NULL	NULL	NULL	5	
-1	SIMPLE	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	SIMPLE	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 DEALLOCATE PREPARE stmt;
@@ -420,7 +420,7 @@ FROM t2
 WHERE PTYPE = 'Design'));
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	5	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 PREPARE stmt FROM "EXPLAIN SELECT EMPNAME
@@ -435,13 +435,13 @@ WHERE EMPNUM IN
 EXECUTE stmt;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	5	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 EXECUTE stmt;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	5	
-1	SIMPLE	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	SIMPLE	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 DEALLOCATE PREPARE stmt;
@@ -568,7 +568,7 @@ FROM t2
 WHERE PTYPE = 'Design'));
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	t1_IDX	NULL	NULL	NULL	5	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 PREPARE stmt FROM "EXPLAIN SELECT EMPNAME
@@ -583,13 +583,13 @@ WHERE EMPNUM IN
 EXECUTE stmt;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	t1_IDX	NULL	NULL	NULL	5	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 EXECUTE stmt;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	t1_IDX	NULL	NULL	NULL	5	
-1	SIMPLE	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	SIMPLE	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 DEALLOCATE PREPARE stmt;
@@ -606,7 +606,7 @@ FROM t2
 WHERE PTYPE = 'Design'));
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	t1_IDX	NULL	NULL	NULL	5	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 PREPARE stmt FROM "EXPLAIN SELECT EMPNAME
@@ -621,13 +621,13 @@ WHERE EMPNUM IN
 EXECUTE stmt;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	t1_IDX	NULL	NULL	NULL	5	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 EXECUTE stmt;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	t1_IDX	NULL	NULL	NULL	5	
-1	SIMPLE	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	SIMPLE	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 DEALLOCATE PREPARE stmt;
@@ -643,7 +643,7 @@ FROM t2
 WHERE PTYPE = 'Design'));
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	5	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 PREPARE stmt FROM "EXPLAIN SELECT EMPNAME
@@ -658,13 +658,13 @@ WHERE EMPNUM IN
 EXECUTE stmt;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	5	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 EXECUTE stmt;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	5	
-1	SIMPLE	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	SIMPLE	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer (flat, BNL join)
 DEALLOCATE PREPARE stmt;

mysql-test/r/subselect_no_mat.result

@@ -1365,7 +1365,7 @@ explain extended select * from t2 where t2.a in (select t1.a from t1,t3 where 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 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)
+1	PRIMARY	t1	ref	a	a	10	test.t2.a,test.t3.a	116	100.00	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`))
 insert into t1 values (3,31);

mysql-test/r/subselect_sj.result

@@ -811,7 +811,7 @@ INSERT INTO t2 VALUES (1,'i','iiii','iiii','iiii','iiii','ffff','ffff','ffff','f
 EXPLAIN EXTENDED SELECT pk FROM t1 WHERE (a, b) IN (SELECT a, b FROM t2 WHERE pk > 0);
 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	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	13	func	1	1.00	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	13	func,func	1	100.00	
 2	SUBQUERY	t2	range	PRIMARY	PRIMARY	4	NULL	2	100.00	Using index condition; Using MRR
 Warnings:
 Note	1003	select `test`.`t1`.`pk` AS `pk` from `test`.`t1` semi join (`test`.`t2`) where ((`test`.`t2`.`pk` > 0))
@@ -980,7 +980,7 @@ FROM t1
 WHERE `varchar_nokey`  < 'n' XOR `pk`  )   ;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	18	100.00	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	8	func	1	1.00	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	8	func,func	1	100.00	
 2	SUBQUERY	t1	ALL	varchar_key	NULL	NULL	NULL	15	100.00	Using where
 Warnings:
 Note	1003	select `test`.`t2`.`varchar_nokey` AS `varchar_nokey` from `test`.`t2` semi join (`test`.`t1`) where ((`test`.`t1`.`varchar_nokey` = `test`.`t1`.`varchar_key`) and ((`test`.`t1`.`varchar_key` < 'n') xor `test`.`t1`.`pk`))
@@ -1062,8 +1062,8 @@ AND t1.val IN (SELECT t3.val FROM t3
 WHERE  t3.val LIKE 'a%' OR t3.val LIKE 'e%');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	5	
-1	PRIMARY	subselect3	eq_ref	unique_key	unique_key	14	func	1	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	14	func	1	
+1	PRIMARY	<subquery3>	eq_ref	distinct_key	distinct_key	14	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	14	func	1	
 3	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	5	Using where
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 SELECT *

mysql-test/r/subselect_sj2.result

@@ -32,7 +32,7 @@ a	b
 9	5
 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	<subquery2>	ALL	distinct_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	Using where
 select * from t2 where b in (select a from t1);
@@ -52,7 +52,7 @@ insert into t3 select a,a, a,a,a from t0;
 explain select * from t3 where b in (select a from t1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t3	ALL	b	NULL	NULL	NULL	10	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	5	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	func	1	
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	3	
 select * from t3 where b in (select a from t1);
 a	b	pk1	pk2	pk3
@@ -75,7 +75,7 @@ A.a + 10*B.a, A.a + 10*B.a, A.a + 10*B.a, A.a + 10*B.a
 from t0 A, t0 B where B.a <5;
 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	<subquery2>	ALL	distinct_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	Using where
 set @save_ecp= @@engine_condition_pushdown;
@@ -102,7 +102,7 @@ set max_heap_table_size= @save_max_heap_table_size;
 explain select * from t1 where a in (select b from t2);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	5	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	func	1	
 2	SUBQUERY	t2	index	b	b	5	NULL	10	Using index
 select * from t1;
 a	b
@@ -130,7 +130,7 @@ explain select
 a, mid(filler1, 1,10), length(filler1)=length(filler2) as Z 
 from t1 ot where a in (select a from t2 it);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	subselect2	ALL	unique_key	NULL	NULL	NULL	22	
+1	PRIMARY	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	22	
 1	PRIMARY	ot	ALL	NULL	NULL	NULL	NULL	32	Using where; Using join buffer (flat, BNL join)
 2	SUBQUERY	it	ALL	NULL	NULL	NULL	NULL	22	
 select 
@@ -164,7 +164,7 @@ a, mid(filler1, 1,10), length(filler1)=length(filler2)
 from t2 ot where a in (select a from t1 it);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	ot	ALL	NULL	NULL	NULL	NULL	22	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	5	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	func	1	
 2	SUBQUERY	it	ALL	NULL	NULL	NULL	NULL	32	
 select 
 a, mid(filler1, 1,10), length(filler1)=length(filler2) 
@@ -198,7 +198,7 @@ explain select
 a, mid(filler1, 1,10), length(filler1)=length(filler2) as Z 
 from t1 ot where a in (select a from t2 it);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	subselect2	ALL	unique_key	NULL	NULL	NULL	22	
+1	PRIMARY	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	22	
 1	PRIMARY	ot	ALL	NULL	NULL	NULL	NULL	52	Using where; Using join buffer (flat, BNL join)
 2	SUBQUERY	it	ALL	NULL	NULL	NULL	NULL	22	
 select 
@@ -232,7 +232,7 @@ a, mid(filler1, 1,10), length(filler1)=length(filler2)
 from t2 ot where a in (select a from t1 it);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	ot	ALL	NULL	NULL	NULL	NULL	22	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	5	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	func	1	
 2	SUBQUERY	it	ALL	NULL	NULL	NULL	NULL	52	
 select 
 a, mid(filler1, 1,10), length(filler1)=length(filler2) 
@@ -349,7 +349,7 @@ WHERE t1.Code IN (
 SELECT t2.CountryCode FROM t2 WHERE Population > 5000000);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	PRIMARY	NULL	NULL	NULL	31	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	CountryCode	NULL	NULL	NULL	545	Using where
 SELECT Name FROM t1 
 WHERE t1.Code IN (
@@ -360,6 +360,10 @@ Canada
 China
 Czech Republic
 drop table t1, t2;
+drop procedure if exists p1;
+drop procedure if exists p2;
+drop procedure if exists p3;
+drop procedure if exists p4;
 CREATE TABLE t1(a INT);
 CREATE TABLE t2(c INT);
 CREATE PROCEDURE p1(v1 int)
@@ -693,7 +697,7 @@ The following must use loose index scan over t3, key a:
 explain select count(a) from t2 where a in ( SELECT  a FROM t3);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	index	a	a	5	NULL	1000	Using index
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	5	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	func	1	
 2	SUBQUERY	t3	index	a	a	5	NULL	30000	Using index
 select count(a) from t2 where a in ( SELECT  a FROM t3);
 count(a)

mysql-test/r/subselect_sj2_jcl6.result

@@ -39,7 +39,7 @@ a	b
 9	5
 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	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	3	
 1	PRIMARY	t2	ref	b	b	5	test.t1.a	2	Using join buffer (flat, BKA join)
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 select * from t2 where b in (select a from t1);
@@ -59,7 +59,7 @@ insert into t3 select a,a, a,a,a from t0;
 explain select * from t3 where b in (select a from t1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t3	ALL	b	NULL	NULL	NULL	10	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	5	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	func	1	
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	3	
 select * from t3 where b in (select a from t1);
 a	b	pk1	pk2	pk3
@@ -82,7 +82,7 @@ A.a + 10*B.a, A.a + 10*B.a, A.a + 10*B.a, A.a + 10*B.a
 from t0 A, t0 B where B.a <5;
 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	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	10	
 1	PRIMARY	t3	ref	b	b	5	test.t0.a	1	Using join buffer (flat, BKA join)
 2	SUBQUERY	t0	ALL	NULL	NULL	NULL	NULL	10	Using where
 set @save_ecp= @@engine_condition_pushdown;
@@ -109,7 +109,7 @@ set max_heap_table_size= @save_max_heap_table_size;
 explain select * from t1 where a in (select b from t2);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	5	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	func	1	
 2	SUBQUERY	t2	index	b	b	5	NULL	10	Using index
 select * from t1;
 a	b
@@ -137,7 +137,7 @@ explain select
 a, mid(filler1, 1,10), length(filler1)=length(filler2) as Z 
 from t1 ot where a in (select a from t2 it);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	subselect2	ALL	unique_key	NULL	NULL	NULL	22	
+1	PRIMARY	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	22	
 1	PRIMARY	ot	ALL	NULL	NULL	NULL	NULL	32	Using where; Using join buffer (flat, BNL join)
 2	SUBQUERY	it	ALL	NULL	NULL	NULL	NULL	22	
 select 
@@ -171,7 +171,7 @@ a, mid(filler1, 1,10), length(filler1)=length(filler2)
 from t2 ot where a in (select a from t1 it);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	ot	ALL	NULL	NULL	NULL	NULL	22	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	5	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	func	1	
 2	SUBQUERY	it	ALL	NULL	NULL	NULL	NULL	32	
 select 
 a, mid(filler1, 1,10), length(filler1)=length(filler2) 
@@ -205,7 +205,7 @@ explain select
 a, mid(filler1, 1,10), length(filler1)=length(filler2) as Z 
 from t1 ot where a in (select a from t2 it);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	subselect2	ALL	unique_key	NULL	NULL	NULL	22	
+1	PRIMARY	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	22	
 1	PRIMARY	ot	ALL	NULL	NULL	NULL	NULL	52	Using where; Using join buffer (flat, BNL join)
 2	SUBQUERY	it	ALL	NULL	NULL	NULL	NULL	22	
 select 
@@ -239,7 +239,7 @@ a, mid(filler1, 1,10), length(filler1)=length(filler2)
 from t2 ot where a in (select a from t1 it);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	ot	ALL	NULL	NULL	NULL	NULL	22	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	5	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	func	1	
 2	SUBQUERY	it	ALL	NULL	NULL	NULL	NULL	52	
 select 
 a, mid(filler1, 1,10), length(filler1)=length(filler2) 
@@ -356,7 +356,7 @@ WHERE t1.Code IN (
 SELECT t2.CountryCode FROM t2 WHERE Population > 5000000);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	PRIMARY	NULL	NULL	NULL	31	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	CountryCode	NULL	NULL	NULL	545	Using where
 SELECT Name FROM t1 
 WHERE t1.Code IN (
@@ -367,6 +367,10 @@ Canada
 China
 Czech Republic
 drop table t1, t2;
+drop procedure if exists p1;
+drop procedure if exists p2;
+drop procedure if exists p3;
+drop procedure if exists p4;
 CREATE TABLE t1(a INT);
 CREATE TABLE t2(c INT);
 CREATE PROCEDURE p1(v1 int)
@@ -702,7 +706,7 @@ The following must use loose index scan over t3, key a:
 explain select count(a) from t2 where a in ( SELECT  a FROM t3);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	index	a	a	5	NULL	1000	Using index
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	5	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	func	1	
 2	SUBQUERY	t3	index	a	a	5	NULL	30000	Using index
 select count(a) from t2 where a in ( SELECT  a FROM t3);
 count(a)

mysql-test/r/subselect_sj_jcl6.result

@@ -818,7 +818,7 @@ INSERT INTO t2 VALUES (1,'i','iiii','iiii','iiii','iiii','ffff','ffff','ffff','f
 EXPLAIN EXTENDED SELECT pk FROM t1 WHERE (a, b) IN (SELECT a, b FROM t2 WHERE pk > 0);
 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	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	13	func	1	1.00	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	13	func,func	1	100.00	
 2	SUBQUERY	t2	range	PRIMARY	PRIMARY	4	NULL	2	100.00	Using index condition; Using MRR
 Warnings:
 Note	1003	select `test`.`t1`.`pk` AS `pk` from `test`.`t1` semi join (`test`.`t2`) where ((`test`.`t2`.`pk` > 0))
@@ -987,7 +987,7 @@ FROM t1
 WHERE `varchar_nokey`  < 'n' XOR `pk`  )   ;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	18	100.00	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	8	func	1	1.00	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	8	func,func	1	100.00	
 2	SUBQUERY	t1	ALL	varchar_key	NULL	NULL	NULL	15	100.00	Using where
 Warnings:
 Note	1003	select `test`.`t2`.`varchar_nokey` AS `varchar_nokey` from `test`.`t2` semi join (`test`.`t1`) where ((`test`.`t1`.`varchar_nokey` = `test`.`t1`.`varchar_key`) and ((`test`.`t1`.`varchar_key` < 'n') xor `test`.`t1`.`pk`))
@@ -1069,8 +1069,8 @@ AND t1.val IN (SELECT t3.val FROM t3
 WHERE  t3.val LIKE 'a%' OR t3.val LIKE 'e%');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	5	
-1	PRIMARY	subselect3	eq_ref	unique_key	unique_key	14	func	1	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	14	func	1	
+1	PRIMARY	<subquery3>	eq_ref	distinct_key	distinct_key	14	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	14	func	1	
 3	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	5	Using where
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	6	Using where
 SELECT *

mysql-test/suite/innodb/r/innodb_mysql.result

@@ -1735,12 +1735,18 @@ 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;
@@ -1749,12 +1755,13 @@ 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))
@@ -1764,12 +1771,13 @@ 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/suite/pbxt/r/group_min_max.result

@@ -2256,7 +2256,8 @@ 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	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	15	
+1	PRIMARY	t1_outer	ref	a	a	5	<subquery2>.max(b)	1	Using index
 2	SUBQUERY	t1	index	NULL	a	10	NULL	15	Using index
 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/suite/pbxt/r/metadata.result

@@ -55,7 +55,7 @@ id	data	data
 2	female	no
 select t1.id from t1 union select t2.id from t2;
 Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
-def				id	id	1	4	1	Y	32768	0	63
+def				id	id	1	4	1	Y	49152	0	63
 id
 1
 2
@@ -66,7 +66,7 @@ insert into t1 values (2,'two');
 set @arg00=1 ;
 select @arg00 FROM t1 where a=1 union distinct select 1 FROM t1 where a=1;
 Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
-def				@arg00	@arg00	8	20	1	Y	32768	0	63
+def				@arg00	@arg00	8	20	1	Y	49152	0	63
 @arg00
 1
 select * from (select @arg00) aaa;
@@ -76,7 +76,7 @@ def			aaa	@arg00	@arg00	8	20	1	Y	32768	0	63
 1
 select 1 union select 1;
 Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
-def				1	1	8	20	1	N	32769	0	63
+def				1	1	8	20	1	N	49153	0	63
 1
 1
 select * from (select 1 union select 1) aaa;

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

@@ -3421,18 +3421,20 @@ 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	<subquery2>	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);
 a	b
+AAA	8
 BBB	4
 CCC	7
-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	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	9	
+1	PRIMARY	t1	ref	a	a	8	<subquery2>.a	1	Using where
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	9	Using temporary; Using filesort
 DROP TABLE t1;
 create table t1( f1 int,f2 int);

mysql-test/suite/vcol/inc/vcol_view.inc

@@ -69,10 +69,14 @@ create table t1 (a int not null,
 insert into t1 (a) values (1), (2), (3), (4);
 create view v1 as select b+1 from t1 order by 1 desc limit 2;
 select * from v1;
+--echo MariaDB-5.3: the following EXPLAIN produces incorrect #rows for table t1.
+--echo MariaDB-5.3: this is expected to go away when FROM subquery optimizations are pushed
 explain select * from v1;
 drop view v1;
 create view v1 as select c+1 from t1 order by 1 desc limit 2;
 select * from v1;
+--echo MariaDB-5.3: the following EXPLAIN produces incorrect #rows for table t1.
+--echo MariaDB-5.3: this is expected to go away when FROM subquery optimizations are pushed
 explain select * from v1;
 drop view v1;
 drop table t1;

mysql-test/suite/vcol/r/vcol_view_innodb.result

@@ -103,20 +103,24 @@ select * from v1;
 b+1
 0
 -1
+MariaDB-5.3: the following EXPLAIN produces incorrect #rows for table t1.
+MariaDB-5.3: this is expected to go away when FROM subquery optimizations are pushed
 explain select * from v1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	2	
-2	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	4	Using filesort
+2	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	2	Using filesort
 drop view v1;
 create view v1 as select c+1 from t1 order by 1 desc limit 2;
 select * from v1;
 c+1
 0
 -1
+MariaDB-5.3: the following EXPLAIN produces incorrect #rows for table t1.
+MariaDB-5.3: this is expected to go away when FROM subquery optimizations are pushed
 explain select * from v1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	2	
-2	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	4	Using filesort
+2	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	2	Using filesort
 drop view v1;
 drop table t1;
 create table t1 (a int,

mysql-test/suite/vcol/r/vcol_view_myisam.result

@@ -103,20 +103,24 @@ select * from v1;
 b+1
 0
 -1
+MariaDB-5.3: the following EXPLAIN produces incorrect #rows for table t1.
+MariaDB-5.3: this is expected to go away when FROM subquery optimizations are pushed
 explain select * from v1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	2	
-2	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	4	Using filesort
+2	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	2	Using filesort
 drop view v1;
 create view v1 as select c+1 from t1 order by 1 desc limit 2;
 select * from v1;
 c+1
 0
 -1
+MariaDB-5.3: the following EXPLAIN produces incorrect #rows for table t1.
+MariaDB-5.3: this is expected to go away when FROM subquery optimizations are pushed
 explain select * from v1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	2	
-2	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	4	Using filesort
+2	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	2	Using filesort
 drop view v1;
 drop table t1;
 create table t1 (a int,

mysql-test/t/subselect_sj2.test

@@ -490,6 +490,12 @@ drop table t1, t2;
 # Bug#33062: subquery in stored routine cause crash
 #
 
+--disable_warnings
+drop procedure if exists p1;
+drop procedure if exists p2;
+drop procedure if exists p3;
+drop procedure if exists p4;
+--enable_warnings
 CREATE TABLE t1(a INT);
 CREATE TABLE t2(c INT);
 

sql-bench/test-table-elimination.sh

+
 #!@PERL@
 # Test of table elimination feature
 

sql/item_cmpfunc.cc

@@ -5894,28 +5894,12 @@ Item_field* Item_equal::get_first(Item_field *field)
   {
     /*
       It's a field from an materialized semi-join. We can substitute it only
-      for a field from the same semi-join.
+      for a field from the same semi-join. Find the first of such items.
     */
-    JOIN_TAB *first= field_tab;
-    JOIN *join= field_tab->join;
-    int tab_idx= field_tab - field_tab->join->join_tab;
 
-    DBUG_ASSERT(join->join_tab[tab_idx].table->map &
-                emb_nest->sj_inner_tables);
-
-    /* Find the first table of this semi-join nest */
-    for (int i= tab_idx-1; i >= (int)join->const_tables; i--)
-    {
-      if (join->join_tab[i].table->map & emb_nest->sj_inner_tables)
-        first= join->join_tab + i;
-      else
-        // Found first tab that doesn't belong to current SJ.
-        break;
-    }
-    /* Find an item to substitute for. */
     while ((item= it++))
     {
-      if (item->field->table->reginfo.join_tab >= first)
+      if (item->field->table->pos_in_table_list->embedding == emb_nest)
       {
         /*
           If we found given field then return NULL to avoid unnecessary
@@ -5927,32 +5911,27 @@ Item_field* Item_equal::get_first(Item_field *field)
   }
   else
   {
-#if 0    
     /*
       The field is not in SJ-Materialization nest. We must return the first
-      field that's not embedded in a SJ-Materialization nest.
-      Example: suppose we have a join order:
+      field in the join order. The field may be inside a semi-join nest, i.e 
+      a join order may look like this:
 
           SJ-Mat(it1  it2)  ot1  ot2
 
-      and equality ot2.col = ot1.col = it2.col
-      If we're looking for best substitute for 'ot2.col', we should pick ot1.col
-      and not it2.col, because when we run a join between ot1 and ot2
-      execution of SJ-Mat(...) has already finished and we can't rely on the
-      value of it*.*.
-      psergey-fix-fix: ^^ THAT IS INCORRECT ^^. Pick the first, whatever that
-      is.
+      where we're looking what to substitute ot2.col for. In this case we must 
+      still return it1.col, here's a proof why:
+
+      First let's note that either it1.col or it2.col participates in 
+      subquery's IN-equality. It can't be otherwise, because materialization is
+      only applicable to uncorrelated subqueries, so the only way we could
+      infer "it1.col=ot1.col" is from the IN-equality. Ok, so IN-eqality has 
+      it1.col or it2.col on its inner side. it1.col is first such item in the
+      join order, so it's not possible for SJ-Mat to be
+      SJ-Materialization-lookup, it is SJ-Materialization-Scan. The scan part
+      of this strategy will unpack value of it1.col=it2.col into it1.col
+      (that's the first equal item inside the subquery), and we'll be able to
+      get it from there. qed.
     */
-    while ((item= it++))
-    {
-      TABLE_LIST *emb_nest= item->field->table->pos_in_table_list->embedding;
-      if (!emb_nest || !emb_nest->sj_mat_info || 
-          !emb_nest->sj_mat_info->is_used)
-      {
-        return item;
-      }
-    }
-#endif
     return fields.head();
   }
   // Shouldn't get here.

sql/item_subselect.h

@@ -46,16 +46,17 @@ class Item_subselect :public Item_result_field
           < child_join->prepare
         < engine->prepare
         *ref= substitution;
+        substitution= NULL;
       < Item_subselect::fix_fields
   */
-  Item *substitution;
 public:
+  Item *substitution;
   /* unit of subquery */
   st_select_lex_unit *unit;
-protected:
   Item *expr_cache;
   /* 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 */
@@ -148,6 +149,7 @@ class Item_subselect :public Item_result_field
   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;
@@ -351,7 +353,9 @@ class Item_in_subselect :public Item_exists_subselect
     all JOIN in UNION
   */
   Item *expr;
+public:
   Item_in_optimizer *optimizer;
+protected:
   bool was_null;
   bool abort_on_null;
 public:
@@ -397,6 +401,16 @@ class Item_in_subselect :public Item_exists_subselect
   };
   enum_exec_method exec_method;
 
+  /*
+    TRUE<=>this is a flattenable semi-join, false overwise.
+  */
+  bool is_flattenable_semijoin;
+  
+  /*
+    Cost to populate the temporary table (set on if-needed basis).
+  */
+  //double startup_cost;
+
   bool *get_cond_guard(int i)
   {
     return pushed_cond_guards ? pushed_cond_guards + i : NULL;
@@ -446,7 +460,7 @@ class Item_in_subselect :public Item_exists_subselect
   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; }
@@ -522,6 +536,7 @@ class subselect_engine: public Sql_alloc
   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
 
@@ -752,7 +767,7 @@ 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. */
@@ -764,14 +779,16 @@ class subselect_hash_sj_engine : public subselect_engine
     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. */
@@ -784,7 +801,9 @@ class subselect_hash_sj_engine : public subselect_engine
     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,
@@ -818,10 +837,11 @@ class subselect_hash_sj_engine : public subselect_engine
   {}
   ~subselect_hash_sj_engine();
 
-  bool init_permanent(List<Item> *tmp_columns);
+  bool init_permanent(List<Item> *tmp_columns, uint subquery_id);
   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

@@ -2909,7 +2909,8 @@ 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())
+  DBUG_ASSERT(!head->is_filled_at_execution());
+  if (keys_to_use.is_clear_all() || head->is_filled_at_execution())
     DBUG_RETURN(0);
   records= head->file->stats.records;
   if (!records)

sql/opt_subselect.h

-/* */
+/*
+  Semi-join subquery optimization code definitions
+*/
 
 #ifdef USE_PRAGMA_INTERFACE
 #pragma interface			/* gcc class implementation */
@@ -366,4 +368,10 @@ int clear_sj_tmp_tables(JOIN *join);
 int rewrite_to_index_subquery_engine(JOIN *join);
 
 
+void get_delayed_table_estimates(TABLE *table,
+                                 ha_rows *out_rows, 
+                                 double *scan_time,
+                                 double *startup_cost);
+
+enum_nested_loop_state join_tab_execution_startup(JOIN_TAB *tab);
 

sql/sql_union.cc

@@ -691,6 +691,7 @@ bool st_select_lex_unit::cleanup()
     {
       join->tables_list= 0;
       join->tables= 0;
+      join->top_jtrange_tables= 0;
     }
     error|= fake_select_lex->cleanup();
     /*