title: cassandra how to handle failed inserts?
body: <p>maybe a user registered into my app.</p>
  <p>Then I do this things:</p>
  <pre><code>const query1 = INSERT INTO users_by_email ... values (...)
  const query2 = INSERT INTO users_by_id ... VALUES (...)
  </code></pre>
  <p>Maybe query2 failed. What do I am then ? Or It cant failed if all datas are correctly ?</p>