On Heroku, I am trying to copy the production database into my staging app using the pgbackups addon. I followed the instructions on the addon page: https://devcenter.heroku.com
First create an up to date backup of production:
heroku pgbackups:capture -a productionappslug --expire
Find out what colour Heroku has named your database.
https://postgres.heroku.com/databases or https://dashboard.heroku.com/apps/STAGINGAPPSLUG/resources
Then load the production db backup into staging (changing RED to whatever colour yours is):
heroku pgbackups:restore HEROKU_POSTGRESQL_RED -a stagingappslug `heroku pgbackups:url -a productionappslug`
stagingappslug and liveappslug are whatever shortnames your heroku apps are called.