Bug#26877788 SELECT FROM INFORMATION_SCHEMA.FILES RETURNS NO RECORDS WHEN ORDER BY IS USED

During subquery materialization table list is modified
so that empty JOIN_TAB table is inserted in the middle of
table list. It leads to interruption of the loop in
get_schema_tables_result() function and tables which are
after empty JOIN_TAB are not processed.

The fix:
Do not interrupt the loop on empty JOIN_TAB.

Author: Sergey Glukhov

mysql-test/r/information_schema.result

@@ -2114,5 +2114,41 @@ DROP TABLE t1;
 CREATE PROCEDURE information_schema.is() BEGIN END;
 ERROR 42000: Access denied for user 'root'@'localhost' to database 'information_schema'
 #
+# Bug#26877788 SELECT FROM INFORMATION_SCHEMA.FILES RETURNS NO RECORDS WHEN ORDER BY IS USED
+#
+EXPLAIN SELECT ENGINE, SUPPORT, TRANSACTIONS FROM INFORMATION_SCHEMA.ENGINES
+WHERE
+SUPPORT IN (
+SELECT DISTINCT SUPPORT
+FROM INFORMATION_SCHEMA.ENGINES
+WHERE
+ENGINE IN (
+SELECT DISTINCT ENGINE FROM INFORMATION_SCHEMA.ENGINES
+WHERE ENGINE IN ('MEMORY')))
+ORDER BY ENGINE;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	ENGINES	ALL	NULL	NULL	NULL	NULL	NULL	Using where; Using filesort
+1	SIMPLE	<subquery2>	eq_ref	<auto_key>	<auto_key>	26	information_schema.ENGINES.SUPPORT	1	NULL
+2	MATERIALIZED	ENGINES	ALL	NULL	NULL	NULL	NULL	NULL	Using where
+2	MATERIALIZED	ENGINES	ALL	NULL	NULL	NULL	NULL	NULL	Using where; Using join buffer (Block Nested Loop)
+SELECT ENGINE, SUPPORT, TRANSACTIONS FROM INFORMATION_SCHEMA.ENGINES
+WHERE
+SUPPORT IN (
+SELECT DISTINCT SUPPORT
+FROM INFORMATION_SCHEMA.ENGINES
+WHERE
+ENGINE IN (
+SELECT DISTINCT ENGINE FROM INFORMATION_SCHEMA.ENGINES
+WHERE ENGINE IN ('MEMORY')))
+ORDER BY ENGINE;
+ENGINE	SUPPORT	TRANSACTIONS
+ARCHIVE	YES	NO
+BLACKHOLE	YES	NO
+CSV	YES	NO
+InnoDB	YES	YES
+MEMORY	YES	NO
+MRG_MYISAM	YES	NO
+PERFORMANCE_SCHEMA	YES	NO
+#
 # End of 5.6 tests
 #

mysql-test/t/information_schema.test

@@ -1878,6 +1878,34 @@ DROP TABLE t1;
 --error ER_DBACCESS_DENIED_ERROR
 CREATE PROCEDURE information_schema.is() BEGIN END;
 
+
+--echo #
+--echo # Bug#26877788 SELECT FROM INFORMATION_SCHEMA.FILES RETURNS NO RECORDS WHEN ORDER BY IS USED
+--echo #
+
+EXPLAIN SELECT ENGINE, SUPPORT, TRANSACTIONS FROM INFORMATION_SCHEMA.ENGINES
+WHERE
+SUPPORT IN (
+SELECT DISTINCT SUPPORT
+FROM INFORMATION_SCHEMA.ENGINES
+WHERE
+ENGINE IN (
+SELECT DISTINCT ENGINE FROM INFORMATION_SCHEMA.ENGINES
+WHERE ENGINE IN ('MEMORY')))
+ORDER BY ENGINE;
+
+SELECT ENGINE, SUPPORT, TRANSACTIONS FROM INFORMATION_SCHEMA.ENGINES
+WHERE
+SUPPORT IN (
+SELECT DISTINCT SUPPORT
+FROM INFORMATION_SCHEMA.ENGINES
+WHERE
+ENGINE IN (
+SELECT DISTINCT ENGINE FROM INFORMATION_SCHEMA.ENGINES
+WHERE ENGINE IN ('MEMORY')))
+ORDER BY ENGINE;
+
+
 --echo #
 --echo # End of 5.6 tests
 --echo #

sql/sql_show.cc

@@ -1,4 +1,4 @@
-/* Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -7484,7 +7484,7 @@ bool get_schema_tables_result(JOIN *join,
   {
     JOIN_TAB *const tab= join->join_tab + i;
     if (!tab->table || !tab->table->pos_in_table_list)
-      break;
+      continue;
 
     TABLE_LIST *table_list= tab->table->pos_in_table_list;
     if (table_list->schema_table && thd->fill_information_schema_tables())