In Koha we have the option to optionally store files with the invoices. This feature is activated by the system preference AcqEnableFiles. The uploaded files are then stored in the database in the the table misc_files. A lot of uploaded files will make backup/restore time for the database larger and it would be nice if we also had the option to store these files in the file system instead. This might have to be optional to keep backwards compatiblity/give people a chance to migrate.