title: Optimistic vs Multi Version Concurrency Control - Differences?
body: <p>I am trying to find out, what the difference between optimistic concurrency control (OCC) and multi version concurrency control (MVCC) is?</p>
  
  <p>So far I know that both is based on version checking for updates. </p>
  
  <p>In OCC, I read about transactions that acquire no locks for reading access, only for the later update which will fail if in between the version was incremented and version checking fails. In this case the transaction will be rolled back.</p>
  
  <p>In MVCC, it is basically the same, or not? Where is the difference?</p>