DBI uses ? as the placeholder character.

Well...yes and no. SQL tends to use '?' as the placeholder (IIRC, its actually part of the std. for embedded SQL). However, variant dialects often use other things, e.g., :1, or :name are common.

If python is using '%something', thats either (a) specific to the DBMS in question or (b) a peccadillo of python (for which python should be shamed!) (I'm blissfully ignorant of python, as every time I try learning it, it bitches about my indentation style).

So I fear you're stuck w/ your regex. Or you should complain to the keepers of Python for varying from the SQL std., to which the DBI does its best to adhere.