[Dbix-class] bugs? distinct SQL

[Fayland Lam]

    my @ips = $c->dbic_log->resultset('login_history')->search( {
    }, {
        select => [
            { distinct => [ 'user_id','IP' ] }
        ],
        as => [ 'user_id','IP' ]
    }
    )->all;

will create SQL:

DBD::mysql::st execute failed: Operand should contain 1 column(s) [for 
Statement "SELECT DISTINCT( user_id, IP ) FROM login_history me"]

which in mysql:
mysql>  SELECT DISTINCT( user_id, IP ) FROM login_history limit 1;
ERROR 1241 (21000): Operand should contain 1 column(s)
mysql>  SELECT DISTINCT user_id, IP FROM login_history limit 1;
+---------+----------------+
| user_id | IP             |
+---------+----------------+
| 15538534 | 220.238.87.172 |
+---------+----------------+
1 row in set (0.18 sec)

with (), mysql will complaint.  version is 5.0.24a.

any hint? Thanks.

-- 
Fayland Lam // http://www.fayland.org/ 
Foorum based on Catalyst // http://www.foorumbbs.com/