diff --git a/mysql-test/r/lock_multi.result b/mysql-test/r/lock_multi.result
index 4b08c175ee2..7a5fb445edf 100644
--- a/mysql-test/r/lock_multi.result
+++ b/mysql-test/r/lock_multi.result
@@ -302,3 +302,49 @@ LOCK TABLES t1 WRITE;
 FLUSH TABLE t1;
 DROP TABLE t1;
 DROP VIEW v1;
+#
+# Test for bug #50913 "Deadlock between open_and_lock_tables_derived
+# and MDL". Also see additional coverage in mdl_sync.test.
+# 
+drop table if exists t1;
+drop view if exists v1;
+create table t1 (i int);
+create view v1 as select i from t1;
+begin;
+select * from t1;
+i
+# Switching to connection 'con50913'.
+# Sending:
+alter table t1 add column j int;
+# Switching to connection 'default'.
+# Wait until ALTER TABLE gets blocked.
+# The below statement should try to acquire SW lock on 't1'
+# and therefore should get ER_LOCK_DEADLOCK error. Before
+# bug fix it acquired SR lock and hung on thr_lock.c lock.
+delete a from t1 as a where i = 1;
+ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
+# Unblock ALTER TABLE.
+commit;
+# Switching to connection 'con50913'.
+# Reaping ALTER TABLE;
+# Switching to connection 'default'.
+begin;
+select * from v1;
+i
+# Switching to connection 'con50913'.
+# Sending:
+alter table t1 drop column j;
+# Switching to connection 'default'.
+# Wait until ALTER TABLE gets blocked.
+# The below statement should try to acquire SW lock on 't1'
+# and therefore should get ER_LOCK_DEADLOCK error. Before
+# bug fix it acquired SR lock and hung on thr_lock.c lock.
+insert into v1 values (1);
+ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
+# Unblock ALTER TABLE.
+commit;
+# Switching to connection 'con50913'.
+# Reaping ALTER TABLE;
+# Switching to connection 'default'.
+drop view v1;
+drop table t1;
diff --git a/mysql-test/r/mdl_sync.result b/mysql-test/r/mdl_sync.result
index 1f1211d964e..1e88d2ad27a 100644
--- a/mysql-test/r/mdl_sync.result
+++ b/mysql-test/r/mdl_sync.result
@@ -2292,3 +2292,33 @@ SET DEBUG_SYNC= 'RESET';
 SET @@global.general_log= @old_general_log;
 SET @@global.log_output= @old_log_output;
 SET @@session.sql_log_off= @old_sql_log_off;
+#
+# Additional coverage for bug #50913 "Deadlock between
+# open_and_lock_tables_derived and MDL". The main test
+# case is in lock_multi.test
+#
+drop table if exists t1;
+set debug_sync= 'RESET';
+create table t1 (i int) engine=InnoDB;
+# Switching to connection 'con50913_1'.
+set debug_sync= 'thr_multi_lock_after_thr_lock SIGNAL parked WAIT_FOR go';
+# Sending:
+alter table t1 add column j int;
+# Switching to connection 'default'.
+# Wait until ALTER TABLE gets blocked on a sync point after
+# acquiring thr_lock.c lock.
+set debug_sync= 'now WAIT_FOR parked';
+# The below statement should wait on MDL lock and not deadlock on
+# thr_lock.c lock.
+# Sending:
+truncate table t1;
+# Switching to connection 'con50913_2'.
+# Wait until TRUNCATE TABLE is blocked on MDL lock.
+# Unblock ALTER TABLE.
+set debug_sync= 'now SIGNAL go';
+# Switching to connection 'con50913_1'.
+# Reaping ALTER TABLE.
+# Switching to connection 'default'.
+# Reaping TRUNCATE TABLE.
+set debug_sync= 'RESET';
+drop table t1;
diff --git a/mysql-test/t/lock_multi.test b/mysql-test/t/lock_multi.test
index df473876c9a..5b64f60b6eb 100644
--- a/mysql-test/t/lock_multi.test
+++ b/mysql-test/t/lock_multi.test
@@ -800,5 +800,82 @@ DROP TABLE t1;
 DROP VIEW v1;
 
 
+--echo #
+--echo # Test for bug #50913 "Deadlock between open_and_lock_tables_derived
+--echo # and MDL". Also see additional coverage in mdl_sync.test.
+--echo # 
+--disable_warnings
+drop table if exists t1;
+drop view if exists v1;
+--enable_warnings
+connect (con50913,localhost,root);
+connection default;
+create table t1 (i int);
+create view v1 as select i from t1;
+begin;
+select * from t1;
+
+--echo # Switching to connection 'con50913'.
+connection con50913;
+--echo # Sending:
+--send alter table t1 add column j int
+
+--echo # Switching to connection 'default'.
+connection default;
+--echo # Wait until ALTER TABLE gets blocked.
+let $wait_condition=
+  select count(*) = 1 from information_schema.processlist
+  where state = "Waiting for table" and info = "alter table t1 add column j int";
+--source include/wait_condition.inc
+--echo # The below statement should try to acquire SW lock on 't1'
+--echo # and therefore should get ER_LOCK_DEADLOCK error. Before
+--echo # bug fix it acquired SR lock and hung on thr_lock.c lock.
+--error ER_LOCK_DEADLOCK
+delete a from t1 as a where i = 1;
+--echo # Unblock ALTER TABLE.
+commit;
+
+--echo # Switching to connection 'con50913'.
+connection con50913;
+--echo # Reaping ALTER TABLE;
+--reap
+
+--echo # Switching to connection 'default'.
+connection default;
+begin;
+select * from v1;
+
+--echo # Switching to connection 'con50913'.
+connection con50913;
+--echo # Sending:
+--send alter table t1 drop column j
+
+--echo # Switching to connection 'default'.
+connection default;
+--echo # Wait until ALTER TABLE gets blocked.
+let $wait_condition=
+  select count(*) = 1 from information_schema.processlist
+  where state = "Waiting for table" and info = "alter table t1 drop column j";
+--source include/wait_condition.inc
+--echo # The below statement should try to acquire SW lock on 't1'
+--echo # and therefore should get ER_LOCK_DEADLOCK error. Before
+--echo # bug fix it acquired SR lock and hung on thr_lock.c lock.
+--error ER_LOCK_DEADLOCK
+insert into v1 values (1);
+--echo # Unblock ALTER TABLE.
+commit;
+
+--echo # Switching to connection 'con50913'.
+connection con50913;
+--echo # Reaping ALTER TABLE;
+--reap
+
+--echo # Switching to connection 'default'.
+connection default;
+disconnect con50913;
+drop view v1;
+drop table t1;
+
+
 # Wait till all disconnects are completed
 --source include/wait_until_count_sessions.inc
diff --git a/mysql-test/t/mdl_sync.test b/mysql-test/t/mdl_sync.test
index 4c1ffc934aa..b59af339229 100644
--- a/mysql-test/t/mdl_sync.test
+++ b/mysql-test/t/mdl_sync.test
@@ -3,6 +3,9 @@
 #
 --source include/have_debug_sync.inc
 
+# We need InnoDB tables for some of the tests.
+--source include/have_innodb.inc
+
 # Save the initial number of concurrent sessions.
 --source include/count_sessions.inc
 
@@ -3315,6 +3318,62 @@ SET @@global.general_log= @old_general_log;
 SET @@global.log_output= @old_log_output;
 SET @@session.sql_log_off= @old_sql_log_off;
 
+
+--echo #
+--echo # Additional coverage for bug #50913 "Deadlock between
+--echo # open_and_lock_tables_derived and MDL". The main test
+--echo # case is in lock_multi.test
+--echo #
+--disable_warnings
+drop table if exists t1;
+--enable_warnings
+set debug_sync= 'RESET';
+connect (con50913_1,localhost,root);
+connect (con50913_2,localhost,root);
+connection default;
+create table t1 (i int) engine=InnoDB;
+
+--echo # Switching to connection 'con50913_1'.
+connection con50913_1;
+set debug_sync= 'thr_multi_lock_after_thr_lock SIGNAL parked WAIT_FOR go';
+--echo # Sending:
+--send alter table t1 add column j int
+
+--echo # Switching to connection 'default'.
+connection default;
+--echo # Wait until ALTER TABLE gets blocked on a sync point after
+--echo # acquiring thr_lock.c lock.
+set debug_sync= 'now WAIT_FOR parked';
+--echo # The below statement should wait on MDL lock and not deadlock on
+--echo # thr_lock.c lock.
+--echo # Sending:
+--send truncate table t1
+
+--echo # Switching to connection 'con50913_2'.
+connection con50913_2;
+--echo # Wait until TRUNCATE TABLE is blocked on MDL lock.
+let $wait_condition=
+  select count(*) = 1 from information_schema.processlist
+  where state = "Waiting for table" and info = "truncate table t1";
+--source include/wait_condition.inc
+--echo # Unblock ALTER TABLE.
+set debug_sync= 'now SIGNAL go';
+
+--echo # Switching to connection 'con50913_1'.
+connection con50913_1;
+--echo # Reaping ALTER TABLE.
+--reap
+
+--echo # Switching to connection 'default'.
+connection default;
+--echo # Reaping TRUNCATE TABLE.
+--reap
+disconnect con50913_1;
+disconnect con50913_2;
+set debug_sync= 'RESET';
+drop table t1;
+
+
 # Check that all connections opened by test cases in this file are really
 # gone so execution of other tests won't be affected by their presence.
 --source include/wait_until_count_sessions.inc
diff --git a/sql/lock.cc b/sql/lock.cc
index f34b6c80872..97756893e2b 100644
--- a/sql/lock.cc
+++ b/sql/lock.cc
@@ -153,6 +153,25 @@ int mysql_lock_tables_check(THD *thd, TABLE **tables, uint count, uint flags)
     {
       system_count++;
     }
+
+    /*
+      If we are going to lock a non-temporary table we must own metadata
+      lock of appropriate type on it (I.e. for table to be locked for
+      write we must own metadata lock of MDL_SHARED_WRITE or stronger
+      type. For table to be locked for read we must own metadata lock
+      of MDL_SHARED_READ or stronger type).
+      The only exception are HANDLER statements which are allowed to
+      lock table for read while having only MDL_SHARED lock on it.
+    */
+    DBUG_ASSERT(t->s->tmp_table ||
+                thd->mdl_context.is_lock_owner(MDL_key::TABLE,
+                                 t->s->db.str, t->s->table_name.str,
+                                 t->reginfo.lock_type >= TL_WRITE_ALLOW_WRITE ?
+                                 MDL_SHARED_WRITE : MDL_SHARED_READ) ||
+                (t->open_by_handler &&
+                 thd->mdl_context.is_lock_owner(MDL_key::TABLE,
+                                  t->s->db.str, t->s->table_name.str,
+                                  MDL_SHARED)));
   }
 
   /*
diff --git a/sql/mysql_priv.h b/sql/mysql_priv.h
index 5ca70302952..6f207ccb00e 100644
--- a/sql/mysql_priv.h
+++ b/sql/mysql_priv.h
@@ -2164,6 +2164,11 @@ MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **table, uint count,
 #define MYSQL_OPEN_FAIL_ON_MDL_CONFLICT         0x0200
 /** Open tables using MDL_SHARED lock instead of one specified in parser. */
 #define MYSQL_OPEN_FORCE_SHARED_MDL             0x0400
+/**
+  Open tables using MDL_SHARED_HIGH_PRIO lock instead of one specified
+  in parser.
+*/
+#define MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL   0x0800
 
 /** Please refer to the internals manual. */
 #define MYSQL_OPEN_REOPEN  (MYSQL_LOCK_IGNORE_FLUSH |\
diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index f68d9a29f05..1564838548f 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -2378,11 +2378,11 @@ open_table_get_mdl_lock(THD *thd, TABLE_LIST *table_list,
         used in the statement being prepared.
       */
       DBUG_ASSERT(!(flags & (MYSQL_OPEN_TAKE_UPGRADABLE_MDL |
-                             MYSQL_LOCK_IGNORE_FLUSH)));
+                             MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL)));
 
       mdl_request->set_type(MDL_SHARED);
     }
-    else if (flags & MYSQL_LOCK_IGNORE_FLUSH)
+    else if (flags & MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL)
     {
       DBUG_ASSERT(!(flags & MYSQL_OPEN_TAKE_UPGRADABLE_MDL));
       mdl_request->set_type(MDL_SHARED_HIGH_PRIO);
diff --git a/sql/sql_delete.cc b/sql/sql_delete.cc
index 0f84f5e9d73..0f5d51f924d 100644
--- a/sql/sql_delete.cc
+++ b/sql/sql_delete.cc
@@ -1052,6 +1052,7 @@ static bool mysql_truncate_by_delete(THD *thd, TABLE_LIST *table_list)
   bool error, save_binlog_row_based= thd->is_current_stmt_binlog_format_row();
   DBUG_ENTER("mysql_truncate_by_delete");
   table_list->lock_type= TL_WRITE;
+  table_list->mdl_request.set_type(MDL_SHARED_WRITE);
   mysql_init_select(thd->lex);
   thd->clear_current_stmt_binlog_format_row();
   /* Delete all rows from table */
diff --git a/sql/sql_handler.cc b/sql/sql_handler.cc
index d9c2a84d03e..9f365d0cf2f 100644
--- a/sql/sql_handler.cc
+++ b/sql/sql_handler.cc
@@ -124,6 +124,7 @@ static void mysql_ha_close_table(THD *thd, TABLE_LIST *tables)
   {
     /* Non temporary table. */
     tables->table->file->ha_index_or_rnd_end();
+    tables->table->open_by_handler= 0;
     mysql_mutex_lock(&LOCK_open);
     if (close_thread_table(thd, &tables->table))
     {
@@ -332,7 +333,8 @@ bool mysql_ha_open(THD *thd, TABLE_LIST *tables, bool reopen)
               hash_tables->table->s->tmp_table);
   /*
     If it's a temp table, don't reset table->query_id as the table is
-    being used by this handler. Otherwise, no meaning at all.
+    being used by this handler. For non-temp tables we use this flag
+    in asserts.
   */
   hash_tables->table->open_by_handler= 1;
 
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index fe49962d77a..1906040d5c6 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -7061,6 +7061,9 @@ bool multi_delete_set_locks_and_link_aux_tables(LEX *lex)
     }
     walk->updating= target_tbl->updating;
     walk->lock_type= target_tbl->lock_type;
+    /* We can assume that tables to be deleted from are locked for write. */
+    DBUG_ASSERT(walk->lock_type >= TL_WRITE_ALLOW_WRITE);
+    walk->mdl_request.set_type(MDL_SHARED_WRITE);
     target_tbl->correspondent_table= walk;	// Remember corresponding table
   }
   DBUG_RETURN(FALSE);
diff --git a/sql/sql_show.cc b/sql/sql_show.cc
index 2238c7bb1ef..2a05cbc561d 100644
--- a/sql/sql_show.cc
+++ b/sql/sql_show.cc
@@ -2928,6 +2928,7 @@ fill_schema_show_cols_or_idxs(THD *thd, TABLE_LIST *tables,
   lex->sql_command= SQLCOM_SHOW_FIELDS;
   res= open_normal_and_derived_tables(thd, show_table_list,
                                       (MYSQL_LOCK_IGNORE_FLUSH |
+                                       MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL |
                                        (can_deadlock ?
                                         MYSQL_OPEN_FAIL_ON_MDL_CONFLICT : 0)));
   lex->sql_command= save_sql_command;
@@ -3507,6 +3508,7 @@ int get_all_tables(THD *thd, TABLE_LIST *tables, COND *cond)
               schema_table->i_s_requested_object;
             res= open_normal_and_derived_tables(thd, show_table_list,
                    (MYSQL_LOCK_IGNORE_FLUSH |
+                    MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL |
                     (can_deadlock ? MYSQL_OPEN_FAIL_ON_MDL_CONFLICT : 0)));
             lex->sql_command= save_sql_command;
             /*
diff --git a/sql/sql_update.cc b/sql/sql_update.cc
index 736dceba837..a163dda2c69 100644
--- a/sql/sql_update.cc
+++ b/sql/sql_update.cc
@@ -1051,6 +1051,11 @@ reopen_tables:
         If we are using the binary log, we need TL_READ_NO_INSERT to get
         correct order of statements. Otherwise, we use a TL_READ lock to
         improve performance.
+        We don't downgrade metadata lock from SW to SR in this case as
+        there is no guarantee that the same ticket is not used by
+        another table instance used by this statement which is going to
+        be write-locked (for example, trigger to be invoked might try
+        to update this table).
       */
       tl->lock_type= read_lock_type_for_table(thd, table);
       tl->updating= 0;
diff --git a/sql/sql_view.cc b/sql/sql_view.cc
index 931a7adb57f..b9eb6a63552 100644
--- a/sql/sql_view.cc
+++ b/sql/sql_view.cc
@@ -1347,7 +1347,11 @@ bool mysql_make_view(THD *thd, File_parser *parser, TABLE_LIST *table,
         anyway.
       */
       for (tbl= view_main_select_tables; tbl; tbl= tbl->next_local)
+      {
         tbl->lock_type= table->lock_type;
+        tbl->mdl_request.set_type((tbl->lock_type >= TL_WRITE_ALLOW_WRITE) ?
+                                  MDL_SHARED_WRITE : MDL_SHARED_READ);
+      }
       /*
         If the view is mergeable, we might want to
         INSERT/UPDATE/DELETE into tables of this view. Preserve the