title: Perform UPDATE without SELECT in eclipselink
body: <p>Is is possible (without writing custom SQL) to have Eclipselink trust me as to whether to perform an update or insert on a merge, rather than perform a select, then an update or insert? If so, how? </p>
  
  <p>In my mind I'd like to use a transient flag and a custom if statement to determine whether the item is already in the database or not, and instruct eclipselink to perform the query required. I understand Hibernate provides this as update() and save()</p>
  
  <p>A few notable points:</p>
  
  <ul>
  <li>I have a large amount of objects that are being batch-merged, as such
  persist() is not suitable for me (also the objects do not exist in the
  library except when they are passed in for the merge anyway)</li>
  <li>Because there are so many objects being merged, it is unlikely that there will be any cache hits, so eclipselink has been unable to tell if its sent it in before via the cache</li>
  <li>Because amount of objects going in (to a non-local database, in this case) the SELECTs are a problem, especially given I can tell which will be required before the operation occurs</li>
  <li>I'd really rather not switch to Hibernate</li>
  </ul>
  
  <p>Thanks. Perhaps I am missing something obvious!</p>