To answer the questions:

• definitely connecting to the same db in both cases
• that's my actual code in all salient points
• it works with the hashref
• it gets the right thing in $min

I'm on DBD version 1.48 but I can't figure out what version of the mysql driver it is. MySQL is 5.1.25-rc, and it's on OS X.

Unfortunately I need to be away from this machine for a while. Thanks for the help so far.