title: Updating indexed document in Elasticsearch
body: <p>I am trying to understand how you update an indexed document in Elasticsearch. I don't understand how it works? What is the <code>ctx</code> that the API is referring to doing? Let say you have a document with nested documents what do you have to do to update it?</p>
  
  <p>And what is the difference between deleting the document and then index the "updated" version, vs a plain update?</p>