code: function createIndexForCollection(collectionName, indexField, indexOpts) {
    var collection = mongoClient.collection(collectionName);
    collection.createIndex(indexField, indexOpts, function(err) {
      if (err) {
        debugError('Failed to create index for collection. collection = %s :: index = %j :: error = %j',collectionName,indexField,err);
      } else {
        debug('Index created for collection. Collection = %s  :: index = %j',collectionName,indexField);
      }
    });
  }
docs: Create an index on the given collection
  @param {String} collectionName
  @param {Object} indexField see mongodb indexes
  @param {Object} indexOpts see mongodb indexes options