I agree that you would normally end up with a compound unique key, but it might have some benefits to know that your transaction I'd was globally unique. Not ju

I agree that you would normally end up with a compound unique key, but it might have some benefits to know that your transaction I'd was globally unique. Not jus per month/weekday - but also on geographic region, stores (eg: avoid need to rewrite/legacy support on store merges/splits, ditto for regions etc).