title: Firestore: Clients and invoices, how to model it
body: <p>I have the following schema and I am not sure how to model it in Firestore.</p>
  
  <p>I will be having clients and invoices. Clients "has" invoices. I need to be able to do these 2 queries:</p>
  
  <ul>
  <li>Show invoices that a client has</li>
  <li>Update all invoices in the system (change a boolean attribute from true to false).</li>
  </ul>
  
  <p>What would be the right way to model this? The first query is satisfied by having a collection of clients with subcollection of their invoices. But the second one is satisfied by having a collection of all invoices? </p>
  
  <p>Any experienced help is appreciated</p>
  
  <p>Thank you</p>