EXPLAIN shows type=range, while SHOW EXPLAIN and userstat show full table scan is used

SELECT MIN(b) FROM ( SELECT * FROM t1, t2, t3 WHERE d = b ) AS alias1 

WHERE SLEEP(0.2) OR c < 'p' OR b = ( SELECT MIN(b) FROM t2 )

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	PRIMARY	t1	system	NULL	NULL	NULL	NULL	1	

1	PRIMARY	t2	range	b	b	5	NULL	2	Using index condition; Using where

1	PRIMARY	t3	ref	d	d	5	test.t2.b	2	Using where; Using index

3	SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	PRIMARY	t1	system	NULL	NULL	NULL	NULL	1	

1	PRIMARY	t2	ALL	b	NULL	NULL	NULL	2	Using where

1	PRIMARY	t3	ref	d	d	5	test.t2.b	2	Using where; Using index

3	SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away

revision-id: psergey@askmonty.org-20120719215203-m2p9cbqb37n0th7n

date: 2012-07-20 01:52:03 +0400

build-date: 2012-07-24 04:43:23 +0400

revno: 3456

CREATE TABLE t1 (a VARCHAR(3) PRIMARY KEY) ENGINE=MyISAM;

INSERT INTO t1 VALUES ('USA');

CREATE TABLE t2 (b INT, c VARCHAR(52), KEY(b)) ENGINE=MyISAM;

INSERT INTO t2 VALUES (3813,'United States'),(3940,'Russia');

CREATE TABLE t3 (d INT, KEY(d)) ENGINE=MyISAM;

INSERT INTO t3 VALUES (12),(22),(9),(45);

EXPLAIN

SELECT MIN(b) FROM ( SELECT * FROM t1, t2, t3 WHERE d = b ) AS alias1 

WHERE SLEEP(0.2) OR c < 'p' OR b = ( SELECT MIN(b) FROM t2 );

--echo #---------------

--echo # SHOW EXPLAIN output:

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

--let $con_id = `SELECT CONNECTION_ID()`

--let $trials = 50

--disable_query_log

while ($trials)

{

  --dec $trials

  --let $run = 1000

  send

  SELECT MIN(b) FROM ( SELECT * FROM t1, t2, t3 WHERE d = b ) AS alias1 

  WHERE SLEEP(0.2) OR c < 'p' OR b = ( SELECT MIN(b) FROM t2 );

  --connection default

  while ($run)

  {

    --error 0,1932

    eval SHOW EXPLAIN FOR $con_id;

    --dec $run

    if (!$mysql_errno)

    {

      --let $run = 0

      --let $trials = 0

      --let $found = 1

    }

  }

  --disable_result_log

  --connection con1

  --reap

  --enable_result_log

}

if (!$found)

{

  --echo ########### Could not catch the query by SHOW EXPLAIN, try again  #############

}

DROP TABLE t1, t2, t3;