Bug#20691429 ASSERTION `CHILD_L' FAILED IN STORAGE/MYISAMMRG/HA_MYISAMMRG.CC:631

test case

mysql-test/r/merge_innodb.result

@@ -35,3 +35,36 @@ c1
 Ann
 Alice
 DROP TABLE t1, t2, t3, t4, t5;
+create table t1 (c1 varchar(100));
+create table t2 (c1 varchar(100));
+create view t3 as select * from t1;
+insert into t1 values ('ann'), ('alice');
+insert into t2 values ('bob'), ('brian');
+create temporary table t4 (c1 varchar(100)) engine=MERGE union=(t2, t1);
+create temporary table t5 (c1 varchar(100)) engine=MERGE union=(t3, t1);
+select * from t5;
+ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist
+lock tables t1 read, t2 read, t3 read, t4 read;
+select * from t5;
+ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist
+select * from t4;
+c1
+bob
+brian
+ann
+alice
+unlock tables;
+drop table t2;
+create view t2 as select * from t1;
+select * from t4;
+ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist
+lock tables t1 read, t2 read, t3 read;
+select * from t4;
+ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist
+select * from t4;
+ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist
+select * from t4;
+ERROR HY000: Unable to open underlying table which is differently defined or of non-MyISAM type or doesn't exist
+unlock tables;
+drop view t2, t3;
+drop table t1;

mysql-test/t/merge_innodb.test

@@ -39,3 +39,34 @@ SELECT * FROM t2;
 SELECT * FROM t1;
 DROP TABLE t1, t2, t3, t4, t5;
 
+#
+# Bug#20691429 temporary merge over view under lock tables
+#
+create table t1 (c1 varchar(100));
+create table t2 (c1 varchar(100));
+create view t3 as select * from t1;
+insert into t1 values ('ann'), ('alice');
+insert into t2 values ('bob'), ('brian');
+create temporary table t4 (c1 varchar(100)) engine=MERGE union=(t2, t1);
+create temporary table t5 (c1 varchar(100)) engine=MERGE union=(t3, t1);
+--error ER_WRONG_MRG_TABLE
+select * from t5;
+lock tables t1 read, t2 read, t3 read, t4 read;
+--error ER_WRONG_MRG_TABLE
+select * from t5;
+select * from t4;
+unlock tables;
+drop table t2;
+create view t2 as select * from t1;
+--error ER_WRONG_MRG_TABLE
+select * from t4;
+lock tables t1 read, t2 read, t3 read;
+--error ER_WRONG_MRG_TABLE
+select * from t4;
+--error ER_WRONG_MRG_TABLE
+select * from t4;
+--error ER_WRONG_MRG_TABLE
+select * from t4;
+unlock tables;
+drop view t2, t3;
+drop table t1;