title: Is `nModified` from mongodb WriteResult a reliable indicator of update result?
body: <p>As far as I know only transactions guarantee complete update of multiple documents that is after invoking <code>updateMany</code> I expect mongo to have updated all of them. Without transactions some documents maybe updated immediately but some may be queued depending on mongodb load.</p>
  
  <p>So I'm wondering what is the purpose of <code>nModified</code> from <a href="https://docs.mongodb.com/manual/reference/method/WriteResult/" rel="nofollow noreferrer">WriteResult</a> when not using transactions? If my update matched 100 documents but <code>nModified</code> is 50 maybe all it means that another 50 documents will be updated soon.</p>