MWL#68 Subquery optimization: Efficient NOT IN execution with NULLs

This patch does three things:
- It adds the possibility to force the execution of top-level [NOT] IN
  subquery predicates via the IN=>EXISTS transformation. This is done by
  setting both optimizer switches partial_match_rowid_merge and
  partial_match_table_scan to "off".
- It adjusts all test cases where the complete optimizer_switch is
  selected because now we have two more switches.
- For those test cases where the plan changes because of the new available
  strategies, we switch off both partial match strategies in order to
  force the "old" IN=>EXISTS strategy. This is done because most of these
  test cases specifically test bugs in this strategy.

sql/opt_subselect.cc:
  Adds the possibility to force the execution of top-level [NOT] IN
  subquery predicates via the IN=>EXISTS transformation. This is done by
  setting both optimizer switches partial_match_rowid_merge and
  partial_match_table_scan to "off".

17 files changed, 105 insertions, 46 deletions

diff --git a/mysql-test/include/mix1.inc b/mysql-test/include/mix1.inc
index 6dabe4864a9..4457ac3a618 100644
--- a/mysql-test/include/mix1.inc
+++ b/mysql-test/include/mix1.inc
@@ -1177,8 +1177,11 @@ DROP TABLE t1;
 
 create table t1 (a bit(1) not null,b int) engine=myisam;
 create table t2 (c int) engine=innodb;
+set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch='partial_match_rowid_merge=off,partial_match_table_scan=off';
 explain
 select b from t1 where a not in (select b from t1,t2 group by a) group by a;
+set optimizer_switch=@save_optimizer_switch;
 DROP TABLE t1,t2;
 
 --echo End of 5.0 tests
diff --git a/mysql-test/r/index_merge_myisam.result b/mysql-test/r/index_merge_myisam.result
index 35410e0756e..7a98f49b21e 100644
--- a/mysql-test/r/index_merge_myisam.result
+++ b/mysql-test/r/index_merge_myisam.result
@@ -1419,19 +1419,19 @@ drop table t1;
 #
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='index_merge=off,index_merge_union=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=off,index_merge_union=off,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+index_merge=off,index_merge_union=off,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='index_merge_union=on';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=off,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+index_merge=off,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='default,index_merge_sort_union=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=off,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+index_merge=on,index_merge_union=on,index_merge_sort_union=off,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch=4;
 ERROR 42000: Variable 'optimizer_switch' can't be set to the value of '4'
 set optimizer_switch=NULL;
@@ -1458,21 +1458,21 @@ set optimizer_switch=default;
 set optimizer_switch='index_merge=off,index_merge_union=off,default';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=off,index_merge_union=off,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+index_merge=off,index_merge_union=off,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch=default;
 select @@global.optimizer_switch;
 @@global.optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 set @@global.optimizer_switch=default;
 select @@global.optimizer_switch;
 @@global.optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 #
 # Check index_merge's @@optimizer_switch flags
 #
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 create table t0 (a int);
 insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
 create table t1 (a int, b int, c int, filler char(100), 
@@ -1582,5 +1582,5 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 set optimizer_switch=default;
 show variables like 'optimizer_switch';
 Variable_name	Value
-optimizer_switch	index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+optimizer_switch	index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 drop table t0, t1;
diff --git a/mysql-test/r/innodb_mysql.result b/mysql-test/r/innodb_mysql.result
index 09f99fcf80e..fd89b54dca9 100644
--- a/mysql-test/r/innodb_mysql.result
+++ b/mysql-test/r/innodb_mysql.result
@@ -1425,12 +1425,15 @@ DROP TABLE t1;
 #
 create table t1 (a bit(1) not null,b int) engine=myisam;
 create table t2 (c int) engine=innodb;
+set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch='partial_match_rowid_merge=off,partial_match_table_scan=off';
 explain
 select b from t1 where a not in (select b from t1,t2 group by a) group by a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables
 2	DEPENDENT SUBQUERY	t1	system	NULL	NULL	NULL	NULL	0	const row not found
 2	DEPENDENT SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	1	
+set optimizer_switch=@save_optimizer_switch;
 DROP TABLE t1,t2;
 End of 5.0 tests
 CREATE TABLE `t2` (
diff --git a/mysql-test/r/myisam_mrr.result b/mysql-test/r/myisam_mrr.result
index 9c52aa663a0..27ae694570f 100644
--- a/mysql-test/r/myisam_mrr.result
+++ b/mysql-test/r/myisam_mrr.result
@@ -394,7 +394,7 @@ drop table t0, t1;
 #   - engine_condition_pushdown does not affect ICP
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 create table t0 (a int);
 insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
 create table t1 (a int, b int, key(a));
diff --git a/mysql-test/r/ps.result b/mysql-test/r/ps.result
index 1f8a077af40..1128253c452 100644
--- a/mysql-test/r/ps.result
+++ b/mysql-test/r/ps.result
@@ -149,6 +149,8 @@ c29 longblob, c30 longtext, c31 enum('one', 'two', 'three'),
 c32 set('monday', 'tuesday', 'wednesday')
 ) engine = MYISAM ;
 create table t2 like t1;
+set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off";
 set @stmt= ' explain SELECT (SELECT SUM(c1 + c12 + 0.0) FROM t2 where (t1.c2 - 0e-3) = t2.c2 GROUP BY t1.c15 LIMIT 1) as scalar_s, exists (select 1.0e+0 from t2 where t2.c3 * 9.0000000000 = t1.c4) as exists_s, c5 * 4 in (select c6 + 0.3e+1 from t2) as in_s, (c7 - 4, c8 - 4) in (select c9 + 4.0, c10 + 40e-1 from t2) as in_row_s FROM t1, (select c25 x, c32 y from t2) tt WHERE x * 1 = c25 ' ;
 prepare stmt1 from @stmt ;
 execute stmt1 ;
@@ -177,6 +179,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 2	DEPENDENT SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables
 deallocate prepare stmt1;
 drop tables t1,t2;
+set @@optimizer_switch=@save_optimizer_switch;
 set @arg00=1;
 prepare stmt1 from ' create table t1 (m int) as select 1 as m ' ;
 execute stmt1 ;
diff --git a/mysql-test/r/subselect.result b/mysql-test/r/subselect.result
index 7e79cf34ad9..cfefc24a88c 100644
--- a/mysql-test/r/subselect.result
+++ b/mysql-test/r/subselect.result
@@ -1,4 +1,6 @@
 drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t11,t12;
+set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off";
 select (select 2);
 (select 2)
 2
@@ -4803,4 +4805,5 @@ SELECT 1 FROM t1 GROUP BY
 1
 1
 DROP TABLE t1;
+set @@optimizer_switch=@save_optimizer_switch;
 End of 5.1 tests.
diff --git a/mysql-test/r/subselect3.result b/mysql-test/r/subselect3.result
index 6d32b476fa0..482cf2ba349 100644
--- a/mysql-test/r/subselect3.result
+++ b/mysql-test/r/subselect3.result
@@ -63,12 +63,15 @@ Handler_read_rnd_next	11
 select ' ^ This must show 11' Z;
 Z
  ^ This must show 11
+set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off";
 explain extended select a in (select max(ie) from t1 where oref=4 group by grp) from t3;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	2	100.00	
 2	DEPENDENT SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	6	100.00	Using where; Using temporary; Using filesort
 Warnings:
 Note	1003	select <in_optimizer>(`test`.`t3`.`a`,<exists>(select max(`test`.`t1`.`ie`) AS `max(ie)` from `test`.`t1` where (`test`.`t1`.`oref` = 4) group by `test`.`t1`.`grp` having trigcond((<cache>(`test`.`t3`.`a`) = <ref_null_helper>(max(`test`.`t1`.`ie`)))))) AS `a in (select max(ie) from t1 where oref=4 group by grp)` from `test`.`t3`
+set @@optimizer_switch=@save_optimizer_switch;
 drop table t1, t2, t3;
 create table t1 (a int, oref int, key(a));
 insert into t1 values 
@@ -692,6 +695,8 @@ a	MAX(b)	test
 2	3	h
 3	4	i
 DROP TABLE t1, t2;
+set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off";
 CREATE TABLE t1 (a int);
 CREATE TABLE t2 (b int, PRIMARY KEY(b));
 INSERT INTO t1 VALUES (1), (NULL), (4);
@@ -759,6 +764,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
 2	DEPENDENT SUBQUERY	t2	unique_subquery	PRIMARY	PRIMARY	4	func	1	Using index; Using where
 DROP TABLE t1, t2;
+set @@optimizer_switch=@save_optimizer_switch;
 CREATE TABLE t1 (a INT);
 INSERT INTO t1 VALUES(1);
 CREATE TABLE t2 (placeholder CHAR(11));
@@ -960,7 +966,7 @@ i1	i2
 # Baseline:
 SHOW STATUS LIKE '%Handler_read_rnd_next';
 Variable_name	Value
-Handler_read_rnd_next	17
+Handler_read_rnd_next	18
 
 INSERT INTO t1 VALUES (NULL, NULL);
 FLUSH STATUS;
@@ -977,7 +983,7 @@ i1	i2
 # (read record from t1, but do not read from t2)
 SHOW STATUS LIKE '%Handler_read_rnd_next';
 Variable_name	Value
-Handler_read_rnd_next	18
+Handler_read_rnd_next	19
 DROP TABLE t1,t2;
 End of 5.1 tests
 CREATE TABLE t1 (
diff --git a/mysql-test/r/subselect3_jcl6.result b/mysql-test/r/subselect3_jcl6.result
index 2c1ae9bd79d..902908f1922 100644
--- a/mysql-test/r/subselect3_jcl6.result
+++ b/mysql-test/r/subselect3_jcl6.result
@@ -67,12 +67,15 @@ Handler_read_rnd_next	11
 select ' ^ This must show 11' Z;
 Z
  ^ This must show 11
+set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off";
 explain extended select a in (select max(ie) from t1 where oref=4 group by grp) from t3;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	2	100.00	
 2	DEPENDENT SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	6	100.00	Using where; Using temporary; Using filesort
 Warnings:
 Note	1003	select <in_optimizer>(`test`.`t3`.`a`,<exists>(select max(`test`.`t1`.`ie`) AS `max(ie)` from `test`.`t1` where (`test`.`t1`.`oref` = 4) group by `test`.`t1`.`grp` having trigcond((<cache>(`test`.`t3`.`a`) = <ref_null_helper>(max(`test`.`t1`.`ie`)))))) AS `a in (select max(ie) from t1 where oref=4 group by grp)` from `test`.`t3`
+set @@optimizer_switch=@save_optimizer_switch;
 drop table t1, t2, t3;
 create table t1 (a int, oref int, key(a));
 insert into t1 values 
@@ -696,6 +699,8 @@ a	MAX(b)	test
 2	3	h
 3	4	i
 DROP TABLE t1, t2;
+set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off";
 CREATE TABLE t1 (a int);
 CREATE TABLE t2 (b int, PRIMARY KEY(b));
 INSERT INTO t1 VALUES (1), (NULL), (4);
@@ -763,6 +768,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
 2	DEPENDENT SUBQUERY	t2	unique_subquery	PRIMARY	PRIMARY	4	func	1	Using index; Using where
 DROP TABLE t1, t2;
+set @@optimizer_switch=@save_optimizer_switch;
 CREATE TABLE t1 (a INT);
 INSERT INTO t1 VALUES(1);
 CREATE TABLE t2 (placeholder CHAR(11));
@@ -964,7 +970,7 @@ i1	i2
 # Baseline:
 SHOW STATUS LIKE '%Handler_read_rnd_next';
 Variable_name	Value
-Handler_read_rnd_next	17
+Handler_read_rnd_next	18
 
 INSERT INTO t1 VALUES (NULL, NULL);
 FLUSH STATUS;
@@ -981,7 +987,7 @@ i1	i2
 # (read record from t1, but do not read from t2)
 SHOW STATUS LIKE '%Handler_read_rnd_next';
 Variable_name	Value
-Handler_read_rnd_next	18
+Handler_read_rnd_next	19
 DROP TABLE t1,t2;
 End of 5.1 tests
 CREATE TABLE t1 (
diff --git a/mysql-test/r/subselect_no_mat.result b/mysql-test/r/subselect_no_mat.result
index 089acb7d277..86ac0810737 100644
--- a/mysql-test/r/subselect_no_mat.result
+++ b/mysql-test/r/subselect_no_mat.result
@@ -1,8 +1,10 @@
 show variables like 'optimizer_switch';
 Variable_name	Value
-optimizer_switch	index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+optimizer_switch	index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='materialization=off';
 drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t11,t12;
+set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off";
 select (select 2);
 (select 2)
 2
@@ -4807,8 +4809,9 @@ SELECT 1 FROM t1 GROUP BY
 1
 1
 DROP TABLE t1;
+set @@optimizer_switch=@save_optimizer_switch;
 End of 5.1 tests.
 set optimizer_switch=default;
 show variables like 'optimizer_switch';
 Variable_name	Value
-optimizer_switch	index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+optimizer_switch	index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
diff --git a/mysql-test/r/subselect_no_opts.result b/mysql-test/r/subselect_no_opts.result
index d02fef65d74..b82fa622932 100644
--- a/mysql-test/r/subselect_no_opts.result
+++ b/mysql-test/r/subselect_no_opts.result
@@ -1,8 +1,10 @@
 show variables like 'optimizer_switch';
 Variable_name	Value
-optimizer_switch	index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+optimizer_switch	index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='materialization=off,semijoin=off';
 drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t11,t12;
+set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off";
 select (select 2);
 (select 2)
 2
@@ -4807,8 +4809,9 @@ SELECT 1 FROM t1 GROUP BY
 1
 1
 DROP TABLE t1;
+set @@optimizer_switch=@save_optimizer_switch;
 End of 5.1 tests.
 set optimizer_switch=default;
 show variables like 'optimizer_switch';
 Variable_name	Value
-optimizer_switch	index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+optimizer_switch	index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
diff --git a/mysql-test/r/subselect_no_semijoin.result b/mysql-test/r/subselect_no_semijoin.result
index 590998a7d63..e2f19db3cc7 100644
--- a/mysql-test/r/subselect_no_semijoin.result
+++ b/mysql-test/r/subselect_no_semijoin.result
@@ -1,8 +1,10 @@
 show variables like 'optimizer_switch';
 Variable_name	Value
-optimizer_switch	index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+optimizer_switch	index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='semijoin=off';
 drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t11,t12;
+set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off";
 select (select 2);
 (select 2)
 2
@@ -4807,8 +4809,9 @@ SELECT 1 FROM t1 GROUP BY
 1
 1
 DROP TABLE t1;
+set @@optimizer_switch=@save_optimizer_switch;
 End of 5.1 tests.
 set optimizer_switch=default;
 show variables like 'optimizer_switch';
 Variable_name	Value
-optimizer_switch	index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+optimizer_switch	index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
diff --git a/mysql-test/r/subselect_sj.result b/mysql-test/r/subselect_sj.result
index d2308f9069c..ec39b06850b 100644
--- a/mysql-test/r/subselect_sj.result
+++ b/mysql-test/r/subselect_sj.result
@@ -202,39 +202,39 @@ BUG#37120 optimizer_switch allowable values not according to specification
 
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='default,materialization=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=on
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='default,semijoin=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=off
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='default,loosescan=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=on,semijoin=on
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='default,semijoin=off,materialization=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=off
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='default,materialization=off,semijoin=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=off
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='default,semijoin=off,materialization=off,loosescan=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=off,semijoin=off
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=off,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='default,semijoin=off,loosescan=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=on,semijoin=off
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=on,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='default,materialization=off,loosescan=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=off,semijoin=on
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=off,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch=default;
 drop table t0, t1, t2;
 drop table t10, t11, t12;
diff --git a/mysql-test/r/subselect_sj_jcl6.result b/mysql-test/r/subselect_sj_jcl6.result
index ab4c5beeab7..3b2218c86c1 100644
--- a/mysql-test/r/subselect_sj_jcl6.result
+++ b/mysql-test/r/subselect_sj_jcl6.result
@@ -206,39 +206,39 @@ BUG#37120 optimizer_switch allowable values not according to specification
 
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='default,materialization=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=on
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='default,semijoin=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=off
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=on,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='default,loosescan=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=on,semijoin=on
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='default,semijoin=off,materialization=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=off
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='default,materialization=off,semijoin=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=off
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=on,materialization=off,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='default,semijoin=off,materialization=off,loosescan=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=off,semijoin=off
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=off,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='default,semijoin=off,loosescan=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=on,semijoin=off
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=on,semijoin=off,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch='default,materialization=off,loosescan=off';
 select @@optimizer_switch;
 @@optimizer_switch
-index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=off,semijoin=on
+index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_condition_pushdown=on,firstmatch=on,loosescan=off,materialization=off,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on
 set optimizer_switch=default;
 drop table t0, t1, t2;
 drop table t10, t11, t12;
diff --git a/mysql-test/t/ps.test b/mysql-test/t/ps.test
index db5994d434b..ba826e6a3e9 100644
--- a/mysql-test/t/ps.test
+++ b/mysql-test/t/ps.test
@@ -163,6 +163,9 @@ create table t1
 ) engine = MYISAM ;
 create table t2 like t1;
 
+set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off";
+
 set @stmt= ' explain SELECT (SELECT SUM(c1 + c12 + 0.0) FROM t2 where (t1.c2 - 0e-3) = t2.c2 GROUP BY t1.c15 LIMIT 1) as scalar_s, exists (select 1.0e+0 from t2 where t2.c3 * 9.0000000000 = t1.c4) as exists_s, c5 * 4 in (select c6 + 0.3e+1 from t2) as in_s, (c7 - 4, c8 - 4) in (select c9 + 4.0, c10 + 40e-1 from t2) as in_row_s FROM t1, (select c25 x, c32 y from t2) tt WHERE x * 1 = c25 ' ;
 prepare stmt1 from @stmt ;
 execute stmt1 ;
@@ -171,6 +174,8 @@ explain SELECT (SELECT SUM(c1 + c12 + 0.0) FROM t2 where (t1.c2 - 0e-3) = t2.c2
 deallocate prepare stmt1;
 drop tables t1,t2;
 
+set @@optimizer_switch=@save_optimizer_switch;
+
 #
 # parameters from variables (for field creation)
 #
diff --git a/mysql-test/t/subselect.test b/mysql-test/t/subselect.test
index 4208211fbd7..a6302cab5d8 100644
--- a/mysql-test/t/subselect.test
+++ b/mysql-test/t/subselect.test
@@ -11,6 +11,9 @@
 drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t11,t12;
 --enable_warnings
 
+set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off";
+
 select (select 2);
 explain extended select (select 2);
 SELECT (SELECT 1) UNION SELECT (SELECT 2);
@@ -4061,4 +4064,6 @@ SELECT 1 FROM t1 GROUP BY
   (SELECT LAST_INSERT_ID() FROM t1 ORDER BY MIN(a) ASC LIMIT 1);
 DROP TABLE t1;
 
+set @@optimizer_switch=@save_optimizer_switch;
+
 --echo End of 5.1 tests.
diff --git a/mysql-test/t/subselect3.test b/mysql-test/t/subselect3.test
index 8ae73587d6e..fa1f916261c 100644
--- a/mysql-test/t/subselect3.test
+++ b/mysql-test/t/subselect3.test
@@ -59,9 +59,13 @@ select a in (select max(ie) from t1 where oref=4 group by grp) from t3;
 show status like 'Handler_read_rnd_next';
 select ' ^ This must show 11' Z;
 
+set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off";
+
 # This must show trigcond:
 explain extended select a in (select max(ie) from t1 where oref=4 group by grp) from t3;
 
+set @@optimizer_switch=@save_optimizer_switch;
 drop table t1, t2, t3;
 
 # 
@@ -529,6 +533,9 @@ SELECT a, MAX(b),
 
 DROP TABLE t1, t2;
 
+# The next three test cases must be executed with the IN=>EXISTS strategy
+set @save_optimizer_switch=@@optimizer_switch;
+set @@optimizer_switch="partial_match_rowid_merge=off,partial_match_table_scan=off";
 
 #
 # Bug #27870: crash of an equijoin query with WHERE condition containing 
@@ -588,6 +595,8 @@ EXPLAIN SELECT a FROM t1 WHERE a NOT IN (SELECT a FROM t2);
 
 DROP TABLE t1, t2;
 
+set @@optimizer_switch=@save_optimizer_switch;
+
 #
 # Bug #34763: item_subselect.cc:1235:Item_in_subselect::row_value_transformer:
 #             Assertion failed, unexpected error message:
diff --git a/sql/opt_subselect.cc b/sql/opt_subselect.cc
index f643971620d..1ac5fc8d5a2 100644
--- a/sql/opt_subselect.cc
+++ b/sql/opt_subselect.cc
@@ -187,7 +187,11 @@ int check_and_do_in_subquery_rewrites(JOIN *join)
              does not call setup_subquery_materialization(). We could make 
              SELECT ... FROM DUAL call that function but that doesn't seem
              to be the case that is worth handling.
-        4. Subquery is non-correlated
+        4. Either the subquery predicate is a top-level predicate, or at
+           least one partial match strategy is enabled. If no partial match
+           strategy is enabled, then materialization cannot be used for
+           non-top-level queries because it cannot handle NULLs correctly.
+        5. Subquery is non-correlated
            TODO:
            This is an overly restrictive condition. It can be extended to:
            (Subquery is non-correlated ||
@@ -195,13 +199,13 @@ int check_and_do_in_subquery_rewrites(JOIN *join)
             (Subquery is correlated to the immediate outer query &&
              Subquery !contains {GROUP BY, ORDER BY [LIMIT],
              aggregate functions}) && subquery predicate is not under "NOT IN"))
-        5. No execution method was already chosen (by a prepared statement).
+        6. No execution method was already chosen (by a prepared statement).
 
         (*) The subquery must be part of a SELECT statement. The current
              condition also excludes multi-table update statements.
 
-        We have to determine whether we will perform subquery materialization
-        before calling the IN=>EXISTS transformation, so that we know whether to
+        Determine whether we will perform subquery materialization before
+        calling the IN=>EXISTS transformation, so that we know whether to
         perform the whole transformation or only that part of it which wraps
         Item_in_subselect in an Item_in_optimizer.
       */
@@ -211,11 +215,14 @@ int check_and_do_in_subquery_rewrites(JOIN *join)
           select_lex->master_unit()->first_select()->leaf_tables &&     // 3
           thd->lex->sql_command == SQLCOM_SELECT &&                     // *
           select_lex->outer_select()->leaf_tables &&                    // 3A
-          subquery_types_allow_materialization(in_subs))
+          subquery_types_allow_materialization(in_subs) &&
+          // psergey-todo: duplicated_subselect_card_check: where it's done?
+          (in_subs->is_top_level_item() ||
+           optimizer_flag(thd, OPTIMIZER_SWITCH_PARTIAL_MATCH_ROWID_MERGE) ||
+           optimizer_flag(thd, OPTIMIZER_SWITCH_PARTIAL_MATCH_TABLE_SCAN)) &&//4
+          !in_subs->is_correlated &&                                  // 5
+          in_subs->exec_method == Item_in_subselect::NOT_TRANSFORMED) // 6
       {
-        // psergey-todo: duplicated_subselect_card_check: where it's done?
-        if (!in_subs->is_correlated &&                                  // 4
-            in_subs->exec_method == Item_in_subselect::NOT_TRANSFORMED) // 5
           in_subs->exec_method= Item_in_subselect::MATERIALIZATION;
       }