ORMs vs. Query Builders: Database portability
There has been some discussion in recent days regarding Object-Relational Mappers (ORMs), Drupal, and why the latter doesn't use the former. There are, actually, many reasons for that, and for why Drupal doesn't do more with the Active Record pattern.
Rather than tuck such discussion away in an issue queue, I figured it better to document a bit more widely.