title: Is there a limit on number of columns you can specify in mongodb composite index?
body: <pre><code>index_dict = {
          "column_7" : 1,
          "column_6" : 1,
          "column_5" : 1,
          "column_4" : 1,
          "column_3" : 1,
          "column_2" : 1,
          "column_1" : 1,
          "column_9" : 1,
          "column_8" : 1,
          "column_11" : 1,
          "column_10" : 1
  }
  
  db.dataCustom.ensureIndex(index_dict, {unique: true, dropDups: true})
  </code></pre>
  
  <p>How many columns is the limit for index_dict? I need to know it for the implementation but I am not able to find the answer online</p>