MySQL password consistency

In MySQL 5.1 when I type:

select 开发者_如何学运维Password('test123');

I get password as 41 bytes long. The same, when typed in older MySQL versions, is 16-bytes long. I need to store 16-byte long passwords, so is there any way to specify length (16-bytes) while retrieving/encrypting the password?

They changed hashing schemes at one point, but you can still use the old one, it's just named OLD_PASSWORD now:

SELECT OLD_PASSWORD('test123');