title: Role of QueryRenderer in Relay Modern?
body: <p>So, first <strong>a bit of background</strong>. 
  I'm a native iOS/Android developer who is now starting my first ever React Native project. It comes with all the benefits and pains of Javascript, but I like it a lot so far :-) I decided to also try my hand at GraphQL for the first time as well.</p>
  
  <p>Being new to the React milieu in general, I also don’t have any prior knowledge of Relay, but chose it on recommendation from friends in my startup community and my web-dev colleagues. I was also warned about a somewhat steep learning curve, but decided to go ahead anyway - I am already fighting an uphill battle with JS and a 0.xx version of a new mobile platform, so what the hell, right? :-) I managed to set up my project correctly and punch a whole through to my GQL server with a <code>QueryRenderer</code>, which was a great relief :-)</p>
  
  <p><strong>So, on to the questions</strong></p>
  
  <p>I'm having a hard time figuring out the container/component relationship, and container composition in general. Reading <a href="https://facebook.github.io/relay/docs/fragment-container.html#container-composition" rel="noreferrer">the docs on composition</a> helped, but I'm still in doubt over the role of the <code>QueryRenderer</code></p>
  
  <ul>
  <li><code>QueryRenderer</code> is said by the docs to be the root container for every Relay tree. Does that mean that one should have a <code>QueryRenderer</code> for the root in our app? Or at the root of each navigation path (i.e. tabs in our app)? Or just for each container component (as opposed to presentational/dumb/pure components, React wise)? Note that I'm not looking for opinions, but arguments for best practice :-)</li>
  <li>Can a <code>FragmentContainer</code> (or any other container, for that matter) work without a <code>QueryRenderer</code> in the ‘parent’ component?</li>
  <li>How is the <code>QueryRenderer</code> linked to child containers? Does it fetch the sum of all the data that child containers want, and then the child containers read from the cache, or? If so, I’ve misunderstood the pros of Relay - we are under the impression that each component can retrieve data independently from every other components, and that each component does not know anything about the data requirements of other components (including parent/child components). I think this assumption is also what confuses me about the <code>QueryRenderer</code>, and the need for a “Root” container.</li>
  <li>If <code>QueryRenderer</code> is a ‘parent’/‘root’ Relay container to a Relay tree, how come it has to render view components based on it’s request? And why does it have to have a request? When and for what should we use a <code>QueryRenderer</code>?</li>
  </ul>
  
  <p>Any help is much appreciated :-)</p>