title: ActiveAdmin automatically loading full association table
body: <p>I'm working on a project that uses ActiveAdmin for its administration backend.</p>
  
  <p>I have two models, a Book model which has_many Products. When I try to access the products index view in ActiveAdmin, it seems to try to load the full books table into memory (there are about 1.5 million books in my database). CPU usage goes up to 100% and memory usage spikes to gigabytes.</p>
  
  <p>Turning on mysql logging confirms that this is what happens when this view is called:</p>
  
  <pre><code>17 Query     SELECT `books`.* FROM `books`
  </code></pre>
  
  <p>As far as I can tell this happens before any attempt to load the products.</p>
  
  <p>To figure out this issue I stripped the models down to their bare bones:</p>
  
  <pre><code>class Product &lt; ActiveRecord::Base
    belongs_to :book
  end
  
  class Book &lt; ActiveRecord::Base
    has_many :products
  end
  </code></pre>
  
  <p>I also reduced the AA definition to its most basic form:</p>
  
  <pre><code>ActiveAdmin.register Product do
  end
  </code></pre>
  
  <p>Is this normal for ActiveAdmin? It doesn't seem like desirable behavior.</p>