SHOW EXPLAIN: Different select_type in plans produced by SHOW EXPLAIN and standard EXPLAIN: 'SUBQUERY' vs 'DEPENDENT SUBQUERY'

SELECT * FROM t1, ( SELECT * FROM t2 ) AS alias

WHERE a < ALL ( SELECT b FROM t1, t2 WHERE a = b )

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	20	Using where

1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	20	Using join buffer (flat, BNL join)

3	DEPENDENT SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	20	

3	DEPENDENT SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	20	Using where; Using join buffer (flat, BNL join)

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	20	Using where

1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	20	Using join buffer (flat, BNL join)

3	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	20	

3	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	20	Using where; Using join buffer (flat, BNL join)

revision-id: psergey@askmonty.org-20120607171922-w5d79pe7733jrh2r

date: 2012-06-07 21:19:22 +0400

revno: 3412

CREATE TABLE t1 (a INT) ENGINE=Aria;

INSERT INTO t1 VALUES

(4),(6),(3),(5),(3),(246),(2),(9),(3),(8),

(1),(8),(8),(5),(7),(5),(1),(6),(2),(9);

CREATE TABLE t2 (b INT) ENGINE=Aria;

INSERT INTO t2 VALUES

(1),(7),(4),(7),(0),(2),(9),(4),(0),(9),

(1),(3),(8),(8),(18),(84),(6),(3),(6),(6);

--connect (con1,localhost,root,,)

let $con_id = `SELECT CONNECTION_ID()`;

EXPLAIN 

SELECT * FROM t1, ( SELECT * FROM t2 ) AS alias

WHERE a < ALL ( SELECT b FROM t1, t2 WHERE a = b );

--send

SELECT * FROM t1, ( SELECT * FROM t2 ) AS alias

WHERE a < ALL ( SELECT b FROM t1, t2 WHERE a = b );

--connection default

let $fail = 100;

while ($fail)

{

  --error 0,ER_ERROR_WHEN_EXECUTING_COMMAND

  --eval SHOW EXPLAIN FOR $con_id

  --dec $fail

  if (!$mysql_errno)

  {

    let $fail = 0;

  }

}

let $pass = 1;

while ($pass)

{

  --error 0,ER_ERROR_WHEN_EXECUTING_COMMAND

  --eval SHOW EXPLAIN FOR $con_id

  if ($mysql_errno)

  {

    let $pass = 0;

  }

}

--connection con1

--disable_result_log

--reap