title: MongoDB null field or true/false
body: <p>On MongoDB, when we have fields such as "draft" (yes/no), "published" (yes/no), etc which is the best strategy? Create the field in all the records and put "yes"/"no" values or put the field just where exists? </p>
  
  <pre><code>posts: [{_id:1, text:"hello", draft:true},{_id:2 text:"world", draft:false}]
  </code></pre>
  
  <p>or</p>
  
  <pre><code>posts: [{_id:1, text:"hello", draft:true},{_id:2 text:"world"}]
  </code></pre>
  
  <p>Which is faster? It's for a large amount of data.</p>
  
  <p>Best regards, João</p>