title: Does with clause in Korma fire one query per item in relationship?
body: <p>The docs at Korma page says,
  under entities,</p>
  
  <pre><code>(has-many email)
        ;; assumes users.id = email.users_id
        ;; but gets the results in a second query
        ;; for each element
  </code></pre>
  
  <p>So, if I am understanding it correctly if one teacher has many students and I want all the students for a teacher nested within each teacher map,
  Korma will generate one SQL query per teacher ?</p>
  
  <p>Won't this hurt the performance when we have like millions of teachers ?</p>