The first time I heard about AREL (Active Relation) for Rails 3 was at a Ruby Meetup in NYC. One of the group members, Ra’Shaun Snuggs, gave a talk about it and I think it’s going to be a powerful tool going forward. Although, I didn’t get past business calculus in school, it was still clear that the level of abstraction offered by AREL will offer great flexibility and potentially efficiency in executing database queries. If I understand it correctly, there are also advantages when dealing with data sets from multiple sources (i.e., an app’s internally generated data as well as data from an external API). While I’m still a ways from being able to grasp or fully utilize a tool like AREL, it is definitely on my radar.
Below are several videos related to AREL in Rails 3: