Fixed the bug mdev-12817/mdev-12820.

This patch is a correction of the patch for bug mdev-12670.
With the current code handling semi-joins the following must
be taken into account.
Conversion of an IN subquery predicate into semi-join
has to be blocked if the predicate occurs:
(a) in the ON expression of an outer join
(b) in the ON expression of an inner join embedded directly
    or indirectly in the inner nest of an outer join.
The patch for mdev-12670 blocked conversion to semi-joins only
in the case (a), but not in the case (b). This patch blocks
the conversion in both cases.

mysql-test/r/subselect_sj.result

@@ -3099,4 +3099,58 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	range	idx	idx	5	NULL	2	Using where; Using index; Using join buffer (flat, BNL join)
 drop table t1,t2;
 set optimizer_switch= @tmp_mdev12675;
+#
+# MDEV-12817: subquery NOT subject to semi-join optimizations  
+#             in ON expression of INNER JOIN
+#
+CREATE TABLE t1 (c1 int) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+CREATE TABLE t2 (c2 int) ENGINE=MyISAM;
+INSERT INTO t2 VALUES (3),(4);
+CREATE TABLE t3 (c3 int) ENGINE=MyISAM;
+INSERT INTO t3 VALUES (5),(6);
+CREATE TABLE t4 (c4 int) ENGINE=MyISAM;
+INSERT INTO t4 VALUES (7),(8);
+SELECT c1 
+FROM t1 
+LEFT JOIN
+( t2 INNER JOIN t3 ON ( 1 IN ( SELECT c4 FROM t4 ) ) )
+ON (c1 = c3);
+c1
+1
+2
+EXPLAIN EXTENDED SELECT c1 
+FROM t1 
+LEFT JOIN
+( t2 INNER JOIN t3 ON ( 1 IN ( SELECT c4 FROM t4 ) ) )
+ON (c1 = c3);
+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	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+2	SUBQUERY	t4	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`c1` AS `c1` from `test`.`t1` left join (`test`.`t2` join `test`.`t3`) on(((`test`.`t3`.`c3` = `test`.`t1`.`c1`) and <cache>(<in_optimizer>(1,<exists>(select `test`.`t4`.`c4` from `test`.`t4` where (1 = `test`.`t4`.`c4`)))))) where 1
+# mdev-12820
+SELECT *
+FROM t1
+LEFT JOIN
+( ( SELECT * FROM t2 WHERE c2 IN ( SELECT c3 FROM t3 ) ) AS sq INNER JOIN t4 )
+ON (c1 = c2);
+c1	c2	c4
+1	NULL	NULL
+2	NULL	NULL
+EXPLAIN EXTENDED SELECT *
+FROM t1
+LEFT JOIN
+( ( SELECT * FROM t2 WHERE c2 IN ( SELECT c3 FROM t3 ) ) AS sq INNER JOIN t4 )
+ON (c1 = c2);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	2	100.00	
+3	DEPENDENT SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`c1` AS `c1`,`test`.`t2`.`c2` AS `c2`,`test`.`t4`.`c4` AS `c4` from `test`.`t1` left join (`test`.`t2` join `test`.`t4`) on(((`test`.`t2`.`c2` = `test`.`t1`.`c1`) and <in_optimizer>(`test`.`t1`.`c1`,<exists>(select `test`.`t3`.`c3` from `test`.`t3` where (<cache>(`test`.`t2`.`c2`) = `test`.`t3`.`c3`))))) where 1
+DROP TABLE t1,t2,t3,t4;
 set optimizer_switch=@subselect_sj_tmp;

mysql-test/r/subselect_sj_jcl6.result

@@ -3113,6 +3113,60 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	range	idx	idx	5	NULL	2	Using where; Using index; Using join buffer (flat, BNL join)
 drop table t1,t2;
 set optimizer_switch= @tmp_mdev12675;
+#
+# MDEV-12817: subquery NOT subject to semi-join optimizations  
+#             in ON expression of INNER JOIN
+#
+CREATE TABLE t1 (c1 int) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+CREATE TABLE t2 (c2 int) ENGINE=MyISAM;
+INSERT INTO t2 VALUES (3),(4);
+CREATE TABLE t3 (c3 int) ENGINE=MyISAM;
+INSERT INTO t3 VALUES (5),(6);
+CREATE TABLE t4 (c4 int) ENGINE=MyISAM;
+INSERT INTO t4 VALUES (7),(8);
+SELECT c1 
+FROM t1 
+LEFT JOIN
+( t2 INNER JOIN t3 ON ( 1 IN ( SELECT c4 FROM t4 ) ) )
+ON (c1 = c3);
+c1
+1
+2
+EXPLAIN EXTENDED SELECT c1 
+FROM t1 
+LEFT JOIN
+( t2 INNER JOIN t3 ON ( 1 IN ( SELECT c4 FROM t4 ) ) )
+ON (c1 = c3);
+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	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where; Using join buffer (flat, BNL join)
+1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where; Using join buffer (incremental, BNL join)
+2	SUBQUERY	t4	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`c1` AS `c1` from `test`.`t1` left join (`test`.`t2` join `test`.`t3`) on(((`test`.`t3`.`c3` = `test`.`t1`.`c1`) and <cache>(<in_optimizer>(1,<exists>(select `test`.`t4`.`c4` from `test`.`t4` where (1 = `test`.`t4`.`c4`)))))) where 1
+# mdev-12820
+SELECT *
+FROM t1
+LEFT JOIN
+( ( SELECT * FROM t2 WHERE c2 IN ( SELECT c3 FROM t3 ) ) AS sq INNER JOIN t4 )
+ON (c1 = c2);
+c1	c2	c4
+1	NULL	NULL
+2	NULL	NULL
+EXPLAIN EXTENDED SELECT *
+FROM t1
+LEFT JOIN
+( ( SELECT * FROM t2 WHERE c2 IN ( SELECT c3 FROM t3 ) ) AS sq INNER JOIN t4 )
+ON (c1 = c2);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where; Using join buffer (flat, BNL join)
+1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	2	100.00	Using join buffer (incremental, BNL join)
+3	DEPENDENT SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`c1` AS `c1`,`test`.`t2`.`c2` AS `c2`,`test`.`t4`.`c4` AS `c4` from `test`.`t1` left join (`test`.`t2` join `test`.`t4`) on(((`test`.`t2`.`c2` = `test`.`t1`.`c1`) and <in_optimizer>(`test`.`t1`.`c1`,<exists>(select `test`.`t3`.`c3` from `test`.`t3` where (<cache>(`test`.`t2`.`c2`) = `test`.`t3`.`c3`))))) where 1
+DROP TABLE t1,t2,t3,t4;
 set optimizer_switch=@subselect_sj_tmp;
 #
 # BUG#49129: Wrong result with IN-subquery with join_cache_level=6 and firstmatch=off

mysql-test/t/subselect_sj.test

@@ -2801,5 +2801,45 @@ select a from t1 join t2 on b between 1 and 2 and a in (select b from t2);
 drop table t1,t2;
 set optimizer_switch= @tmp_mdev12675;
 
+--echo #
+--echo # MDEV-12817: subquery NOT subject to semi-join optimizations  
+--echo #             in ON expression of INNER JOIN
+--echo #
+
+CREATE TABLE t1 (c1 int) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1),(2);
+
+CREATE TABLE t2 (c2 int) ENGINE=MyISAM;
+INSERT INTO t2 VALUES (3),(4);
+ 
+CREATE TABLE t3 (c3 int) ENGINE=MyISAM;
+INSERT INTO t3 VALUES (5),(6);
+ 
+CREATE TABLE t4 (c4 int) ENGINE=MyISAM;
+INSERT INTO t4 VALUES (7),(8);
+
+let $q1= 
+SELECT c1 
+FROM t1 
+LEFT JOIN
+( t2 INNER JOIN t3 ON ( 1 IN ( SELECT c4 FROM t4 ) ) )
+ON (c1 = c3);
+
+eval $q1;
+eval EXPLAIN EXTENDED $q1;
+
+let $q2= 
+SELECT *
+FROM t1
+LEFT JOIN
+( ( SELECT * FROM t2 WHERE c2 IN ( SELECT c3 FROM t3 ) ) AS sq INNER JOIN t4 )
+ON (c1 = c2);
+
+--echo # mdev-12820
+eval $q2;
+eval EXPLAIN EXTENDED $q2;
+
+DROP TABLE t1,t2,t3,t4;
+
 # The following command must be the last one the file 
 set optimizer_switch=@subselect_sj_tmp;

sql/opt_subselect.cc

@@ -1103,7 +1103,26 @@ bool convert_join_subqueries_to_semijoins(JOIN *join)
     do
     {
       embedded= embedding;
-      if (test(embedded->outer_join))
+      bool block_conversion_to_sj= false;
+      if (embedded->on_expr)
+      {
+        /*
+          Conversion of an IN subquery predicate into semi-join
+          is blocked now if the predicate occurs:
+          - in the ON expression of an outer join
+          - in the ON expression of an inner join embedded directly
+            or indirectly in the inner nest of an outer join
+	*/
+        for (TABLE_LIST *tl= embedded; tl; tl= tl->embedding)
+	{
+          if (tl->outer_join)
+	  {
+            block_conversion_to_sj= true;
+            break;
+          }
+        }
+      }
+      if (block_conversion_to_sj)
       {
 	Item *cond= embedded->on_expr;
         if (!cond)