Thankfully this is a hypothetical, planning-ahead sort of a question. Can you restore part of a database using Heroku's backup addon, or otherwise? So, for instance, only restore records in all tables which have a client_id of 5?
No, that does not appear to be a feature included in the PG Backups addon provided by Heroku: http://devcenter.heroku.com/articles/pgbackups#restoring_from_a_backup