Alexander Barkov added a comment - 2016-05-12 10:44 - edited By the way, this syntax is not standard: SELECT * FROM ( WITH a AS ( SELECT * FROM t1) (t2 NATURAL JOIN t3)); <with clause> cannot be followed by a <parenthesized joined table>. It can be followed by <query expression> only. The correct standard syntax is: SELECT * FROM ( WITH a AS ( SELECT * FROM t1) SELECT * FROM t2 NATURAL JOIN t3) AS d1; And EXPLAIN for this standard query crashes. See MDEV-10057 .

Sergei Petrunia added a comment - 2016-09-04 10:39 On the current 10.2 tree: MariaDB [j8]> EXPLAIN SELECT * FROM (WITH a AS (SELECT * FROM t1) (t2 NATURAL JOIN t3)); ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 't2 NATURAL JOIN t3))' at line 1 MariaDB [j8]> explain SELECT * FROM (WITH a AS (SELECT * FROM t1) SELECT * FROM t2 NATURAL JOIN t3) AS d1; +------+-------------+-------+------+---------------+------+---------+------+------+-------------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +------+-------------+-------+------+---------------+------+---------+------+------+-------------------------------------------------+ | 1 | PRIMARY | t2 | ALL | NULL | NULL | NULL | NULL | 3 | | | 1 | PRIMARY | t3 | ALL | NULL | NULL | NULL | NULL | 3 | Using where; Using join buffer (flat, BNL join) | +------+-------------+-------+------+---------------+------+---------+------+------+-------------------------------------------------+ 2 rows in set (0.00 sec)

Sergei Petrunia added a comment - 2016-09-04 10:40 So, the non-standard syntax is not accepted anymore the standard syntax query doesn't crash and EXPLAIN output looks reasonable.