Starting today, Postgres 9.5 is now the new default version for all new Heroku Postgres databases. We’ve had hundreds of customers using early beta versions of 9.5 and the feedback has been positive. For many customers, the new UPSERT functionality was the last feature that prevented many of them from moving from other relational databases to Postgres. The engineering staff at Heroku and the Postgres community at large has spent years bringing UPSERT to fruition and the customer feedback is a testament to that hard work. If you want to try out the new version, getting it is as simple as provisioning a new database:
$ heroku addons:create heroku-postgresql -a sushi
More UPSERT
UPSERT,...