I think Heroku played less than a role than it sounds like. Sure, they offered it for Rails, but working with Rails especially back then a typical Rails applica

I think Heroku played less than a role than it sounds like. Sure, they offered it for Rails, but working with Rails especially back then a typical Rails application made very little use of any of the features. It typically was and to a degree still is tables rather than arrays, application defined integers instead of Postgres Enums, in general very little user defined types, Rail's validation system instead of Postgres constraints (even automatic querying for duplicates). Sure it might have made people hear about Postgres, but I think few people using ORMs really could tell you anything about any of all the amazing features that Postgres has. I think Arrays might be the main one.