title: Does an UPDATE become an implied INSERT
body: <p>For Cassandra, do <code>UPDATE</code>s become an implied <code>INSERT</code> if the selected row does not exist? That is, if I say</p>
  
  <pre><code> UPDATE users SET name = "Raedwald" WHERE id = 545127
  </code></pre>
  
  <p>and <code>id</code> is the <code>PRIMARY KEY</code> of the <code>users</code> table, and the table has no row with a key of 545127, will that be equivalent to </p>
  
  <pre><code> INSERT INTO users (id, name) VALUES (545127, "Raedwald")
  </code></pre>
  
  <p>I know that the opposite is true: an <code>INSERT</code> for an <code>id</code> that already exists becomes an <code>UPDATE</code> of the row with that <code>id</code>. Older Cassandra documentation talked about inserts actually being "upserts" for that reason.</p>
  
  <p>I'm interested in the case for CQL3, Cassandra version 1.2+.</p>