Completely agree here. Your live transactional system needs to export reportable data - this can come in the form of a DB backup/download (which I've done many

Completely agree here. Your live transactional system needs to export reportable data - this can come in the form of a DB backup/download (which I've done many times) so you can run queries locally or by pushing CSVs using a cron job. You can use a SQL query for this or a simple map/reduce - either way my argument is to focus on transactional design that works best for your system - don't conflate reporting needs with your live system (i.e. BA queries).