title: Create an ActiveRecord database table with no :id column?
body: <p>Is it possible for me to create and use a <strong>database table</strong> that contains no <strong>:id</strong> column in ActiveRecord, Ruby on Rails.</p>
  
  <p>I don't merely want to ignore the <strong>id column</strong>, but I wish it to be absolutely non-existent. </p>
  
  <pre><code>Table Example
  
  :key_column                         :value_column
  0cc175b9c0f1b6a831c399e269772661    0cc175b9c0f1b6a831c399e269772661
  4a8a08f09d37b73795649038408b5f33    0d61f8370cad1d412f80b84d143e1257
  92eb5ffee6ae2fec3ad71c777531578f    9d5ed678fe57bcca610140957afab571
  </code></pre>
  
  <p>Any more info ( like an :id_column ) would break the whole feature.</p>
  
  <p>How would I implement something like this in rails?</p>