in reply to DBD::mysql Unusual Behavior

Probably way off here, but isn't the correct way to test for the existance of a key exists rather than defined?

Doesn't the use of defined($pair->{unknown key} cause that unknown key to be autovivified? )

That's what I seem to remembering reading somewhere. I'll update if I find the reference. Not sure if that is the cause of your problem though.

What's this about a "crooked mitre"? I'm good at woodwork!