title: How to create unique items in RethinkDB
body: <p>How to create unique items in RethinkDB?</p>
  
  <p>In MongoDb I used <code>ensureIndex</code> for this, eg:</p>
  
  <pre><code>userCollection.ensureIndex({email:1},{unique:true},function(err, indexName){
  </code></pre>