title: Is it possible for a Grails Domain to have no 'id'?
body: <p>Is it possible to create a table that has no 'id'? For example, this is my domain:</p>
  
  <pre><code>class SnbrActVector {
  
      int nid
      String term
      double weight
  
      static mapping = {
          version false
          id generator: 'identity'
      }
  
      static constraints = {
      }
  }
  </code></pre>
  
  <p>When I run this SQL statement, it fails:</p>
  
  <pre><code>insert into snbr_act_vector values (5, 'term', 0.5)
  </code></pre>
  
  <p>I checked the table and 'id' is already set to autoincrement. I'm thinking that another option is to remove the 'id' itself. Or is there another workaround for this? Please assume that it is not an option to change the givent SQL statement.</p>