backward compatibility, mysql 3.23->3.21

I want to set up a site using the PHPshop shopping cart system (http://www.phpshop.org). However, PHPshop requires MySQL 3.22.x or higher and my ISP offers only 3.21.29-gamma. They say they are unwilling to upgrade because of backward compatibility issues (they don't want to break any sites using MySQL 3.21.29-gamma. My understanding is that the current 3.23 versions should off full backward compatibility. Does anyone know of any issues? Anyone done this upgrade? Does anyone know of an official statement somewhere stating that 3.23 provides backward compatibility back to version X?

The ISP seems amenable to an upgrade if they had some reassurance, so any help would be appreciated.

Sorry for that post. I found the answer. According to the MySQL manual,
section 4.16.2 ("Upgrading from a 3.21 version to 3.22") there are two main
issues:

1. you need to run a script to set various privileges (no problem).

2. [quote]
The C API interface to mysql_real_connect() has changed. If you have an old
client program that calls this function, you
must place a 0 for the new db argument (or recode the client to send the db
element for faster connections). You must also call
mysql_init() before calling mysql_real_connect()!
[endquote]

So I can see why my ISP won't upgrade. They would have to make sure that
everyone using this call updates their site, which is a lot to ask.

Cheers,

Tom