Data validation should be done before candlepin is upgraded from 0.9.x to 2.x. Currently candlepin does this during the 2.x DB upgrade process via liquibase. It would be better to be able to perform the validation 'on demand' before any actual update occurs. cpdb should be updated to enable running the validation step independently, before updating to 2.x, so that any issues can be addressed before the actual upgrade begins.