public function installCollections()
    {
        $collections = $this->mongoInstance->listCollections();

        foreach ($collections as $collection) {
            /* @var $collection CollectionInfo */
            if ($collection->getName() == self::collection) {
                return true;
            }
        }

        $this->mongoInstance->createCollection(self::collection);
        $this->mongoInstance->createIndex(self::collection, new SingleIndex('key', 'key', false, true));
        $this->mongoInstance->createIndex(self::collection, new SingleIndex('ttl', 'ttl', false, false, false, 0));

        return true;

    }