title: Why are composite primary keys still around?
body: <p>I'm assigned to migrate a database to a mid-class ERP.
  The new system uses composite primary keys here and there, and from a pragmatic point of view, why?</p>
  
  <p>Compared to autogenerated IDs, I can only see negative aspects;</p>
  
  <ul>
  <li>Foreign keys becomes blurry</li>
  <li>Harder migration or db-redesigns</li>
  <li>Inflexible as business change. (My car has no reg.plate..)</li>
  <li>Same integrity better achieved with constraints.</li>
  </ul>
  
  <p>It's falling back to the design concept of candiate keys, which I neither see the point of.</p>
  
  <p>Is it a habit/artifact from the floppy-days (minimizing space/indexes), or am I missing something?</p>
  
  <p>//edit//
  Just found good SO-post: <a href="https://stackoverflow.com/questions/159087/composite-primary-keys-versus-unique-object-id-field">Composite primary keys versus unique object ID field</a>
  //</p>