GROUP BY handler doesn't support outer join.

MariaDB [tpch1c]> set infinidb_vtable_mode=0;

Query OK, 0 rows affected (0.00 sec)

MariaDB [tpch1c]>  SELECT C_COUNT, COUNT(*) AS CUSTDIST FROM ( SELECT C_CUSTKEY, COUNT(c_nationKEY) c_COUNT FROM  region left outer join customer on   c_nationkey = r_regionkey AND  r_comment not like '%%express%%requests%%' GROUP BY  C_CUSTKEY ) C_ORDERS GROUP BY C_COUNT ORDER BY  CUSTDIST DESC, C_COUNT DESC;

ERROR 1815 (HY000): Internal error: IDB-1000: 'region' and 'customer' are not joined.