title: When does Rails perform the query and loads into memory?
body: <p>If I have a User table and House table and I do this:</p>
  
  <pre><code>users = User.where(status: 3)
  
  homes = Home.joins(:user).merge(users)
  </code></pre>
  
  <p>On the first assignation am I performing a query already? Or it waits until the second to perform the query? Or it does it when you actually try to access any of those results? How does Rails manage to know when to perform the query?</p>