Notes:
The DBD::AnyData allows your perl application to have full SQL access to any storage format that is supported by AnyData. It gets emulated by SQL::Statement, so there's no need to run a daemon.
Now you can do SELECT statements on your CSV file!
If you have an application that is run by many users, you can use DBD::AnyData to get a feature for free. Let the users decide if they want a flat file or database back end. Either way, you just need to maintain the SQL.