sp: select from INFORMATION_SCHEMA => read lock

[jholec]

Why the read lock? Isn't this a bug?

Script started on Mon Dec 5 11:16:44 2005
$ cat test.sql
SELECT version();
DESCRIBE tmp;

DELIMITER //
CREATE PROCEDURE addcolumn_ifnx ()
BEGIN
IF NOT EXISTS(
SELECT 1 FROM INFORMATION_SCHEMA.COLUMNS
WHERE (TABLE_NAME = 'tmp')
AND (TABLE_SCHEMA = 'dbname')
AND (COLUMN_NAME = 'b'))
THEN
ALTER TABLE tmp ADD COLUMN b int not null;
END IF;
END//
DELIMITER ;
CALL addcolumn_ifnx();
DROP PROCEDURE addcolumn_ifnx;


$ mysql -uusername -ppassword -hhostname dbname <test.sql
version()
5.0.10a-beta-nt
Field Type Null Key Default Extra
a int(11) YES NULL
c int(11) YES NULL
ERROR 1099 (HY000) at line 17: Table 'tmp' was locked with a READ lock and can't be updated
$
Script done on Mon Dec 5 11:17:10 2005