4 files changed, 60 insertions, 3 deletions
diff --git a/mysql-test/include/index_merge_ror_cpk.inc b/mysql-test/include/index_merge_ror_cpk.inc
index cfc2ed3885e..3912aa34026 100644
--- a/mysql-test/include/index_merge_ror_cpk.inc
+++ b/mysql-test/include/index_merge_ror_cpk.inc
@@ -126,3 +126,19 @@ WHERE
 
 drop table t1;
 
+--echo #
+--echo # Bug#50402 Optimizer producing wrong results when using Index Merge on InnoDB
+--echo #
+CREATE TABLE t1 (f1 INT, PRIMARY KEY (f1));
+INSERT INTO t1 VALUES (2);
+CREATE TABLE t2 (f1 INT, f2 INT, f3 char(1),
+                 PRIMARY KEY (f1), KEY (f2), KEY (f3) );
+INSERT INTO t2 VALUES (1, 1, 'h'), (2, 3, 'h'), (3, 2, ''), (4, 2, '');
+
+SELECT t1.f1 FROM t1
+WHERE (SELECT COUNT(*) FROM t2 WHERE t2.f3 = 'h' AND t2.f2 = t1.f1) = 0 AND t1.f1 = 2;
+
+EXPLAIN SELECT t1.f1 FROM t1
+WHERE (SELECT COUNT(*) FROM t2 WHERE t2.f3 = 'h' AND t2.f2 = t1.f1) = 0 AND t1.f1 = 2;
+
+DROP TABLE t1,t2;
diff --git a/mysql-test/r/index_merge_innodb.result b/mysql-test/r/index_merge_innodb.result
index 6d130a64e35..8bbbed2865f 100644
--- a/mysql-test/r/index_merge_innodb.result
+++ b/mysql-test/r/index_merge_innodb.result
@@ -255,3 +255,21 @@ WHERE
 `RUNID`= '' AND `SUBMITNR`= '' AND `ORDERNR`='' AND `PROGRAMM`='' AND
 `TESTID`='' AND `UCCHECK`='';
 drop table t1;
+#
+# Bug#50402 Optimizer producing wrong results when using Index Merge on InnoDB
+#
+CREATE TABLE t1 (f1 INT, PRIMARY KEY (f1));
+INSERT INTO t1 VALUES (2);
+CREATE TABLE t2 (f1 INT, f2 INT, f3 char(1),
+PRIMARY KEY (f1), KEY (f2), KEY (f3) );
+INSERT INTO t2 VALUES (1, 1, 'h'), (2, 3, 'h'), (3, 2, ''), (4, 2, '');
+SELECT t1.f1 FROM t1
+WHERE (SELECT COUNT(*) FROM t2 WHERE t2.f3 = 'h' AND t2.f2 = t1.f1) = 0 AND t1.f1 = 2;
+f1
+2
+EXPLAIN SELECT t1.f1 FROM t1
+WHERE (SELECT COUNT(*) FROM t2 WHERE t2.f3 = 'h' AND t2.f2 = t1.f1) = 0 AND t1.f1 = 2;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t1	const	PRIMARY	PRIMARY	4	const	1	Using index
+2	DEPENDENT SUBQUERY	t2	index_merge	f2,f3	f3,f2	2,5	NULL	1	Using intersect(f3,f2); Using where; Using index
+DROP TABLE t1,t2;
diff --git a/mysql-test/r/index_merge_myisam.result b/mysql-test/r/index_merge_myisam.result
index 1be96da5c7d..7377b450872 100644
--- a/mysql-test/r/index_merge_myisam.result
+++ b/mysql-test/r/index_merge_myisam.result
@@ -1414,6 +1414,24 @@ WHERE
 `TESTID`='' AND `UCCHECK`='';
 drop table t1;
 #
+# Bug#50402 Optimizer producing wrong results when using Index Merge on InnoDB
+#
+CREATE TABLE t1 (f1 INT, PRIMARY KEY (f1));
+INSERT INTO t1 VALUES (2);
+CREATE TABLE t2 (f1 INT, f2 INT, f3 char(1),
+PRIMARY KEY (f1), KEY (f2), KEY (f3) );
+INSERT INTO t2 VALUES (1, 1, 'h'), (2, 3, 'h'), (3, 2, ''), (4, 2, '');
+SELECT t1.f1 FROM t1
+WHERE (SELECT COUNT(*) FROM t2 WHERE t2.f3 = 'h' AND t2.f2 = t1.f1) = 0 AND t1.f1 = 2;
+f1
+2
+EXPLAIN SELECT t1.f1 FROM t1
+WHERE (SELECT COUNT(*) FROM t2 WHERE t2.f3 = 'h' AND t2.f2 = t1.f1) = 0 AND t1.f1 = 2;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t1	system	PRIMARY	NULL	NULL	NULL	1	
+2	DEPENDENT SUBQUERY	t2	ref	f2,f3	f2	5		1	Using where
+DROP TABLE t1,t2;
+#
 # Generic @@optimizer_switch tests (move those into a separate file if
 #  we get another @@optimizer_switch user)
 #
diff --git a/sql/opt_range.cc b/sql/opt_range.cc
index b9819def54d..ffff9e3f6c8 100644
--- a/sql/opt_range.cc
+++ b/sql/opt_range.cc
@@ -8550,9 +8550,14 @@ int QUICK_RANGE_SELECT::reset()
   in_range= FALSE;
   cur_range= (QUICK_RANGE**) ranges.buffer;
 
-  if (file->inited == handler::NONE && (error= file->ha_index_init(index,1)))
-    DBUG_RETURN(error);
- 
+  if (file->inited == handler::NONE)
+  {
+    if (in_ror_merged_scan)
+      head->column_bitmaps_set_no_signal(&column_bitmap, &column_bitmap);
+    if ((error= file->ha_index_init(index,1)))
+        DBUG_RETURN(error);
+  }
+
   /* Do not allocate the buffers twice. */
   if (multi_range_length)
   {