Rails 3.1 with PostgreSQL: GROUP BY must be used in an aggregate function

Question

I am trying to load the latest 10 Arts grouped by the user_id and ordered by created_at. This works fine with SqlLite and MySQL, but gives an error on my new PostgreSQL data

Answer 1

Take a look at this post SQLite to Postgres (Heroku) GROUP BY

PostGres is actually following the SQL standard here whilst sqlite and mysql break from the standard.