Motivation

When you first hear of Drupal's hook_views_query_alter you think you get it. You understand Drupal's hook system (presumeably, otherwise start here), you've used other hooks before, maybe you even experience a twinge of guilty excitement that it's one of the hooks that hasn't been removed from Drupal 8. You think to yourself, okay, this function will be passed a query argument, and I'll alter it -- and you're right! But it turns out it's a little more complicated than it sounds.