title: Scaling with regard to Nested vs Parent/Child Documents
body: <p>I'm running a proof of concept for us to run nested queries on more "normalised" data in ES. </p>
  
  <p>e.g. with nested </p>
  
  <p>Customer -> 
       - name<br>
       - email 
       - events -> 
             - created 
             - type </p>
  
  <p>Now I have a situation where a list of events for a given customer can be moved to another customer. e.g. Customer A has 50 events 
  Customer B has 5000 events </p>
  
  <p>I now want to move all events from customer A into Customer B </p>
  
  <p>At scale with millions of customers and queries are run on this for graphs in a UI is Parent/Child more suitable or should nested be able to handle it? </p>
  
  <p>What are the pros and cons in my situation? </p>