yii\mongodb\Migration::createIndex PHP Method

    public function createIndex($collection, $columns, $options = [])
    {
        $this->beginProfile($token = "    > create index on " . $this->composeCollectionLogName($collection) . " (" . Json::encode((array) $columns) . empty($options) ? "" : ", " . Json::encode($options) . ") ...");
        $this->db->getCollection($collection)->createIndex($columns, $options);
        $this->endProfile($token);
    }