code: function(datasetClientId, fields, records, callback) {
        return metrics.timeAsyncFunc(metrics.KEYS.MONGODB_OPERATION_TIME, doUpdateDatasetClientWithRecords)(datasetClientId, fields, records, callback);
      }
docs: update the given dataset client with the given records
  @param {String} datasetClientId the id of the datasetClient
  @param {storage~DatasetClient} fields the fields to update
  @param {storage~DatasetClientRecord[]} records an array of records to save
  @param {Function} callback