public function buildIndex($bucketName, $indexNames)
    {
        $indexNames = is_array($indexNames) ? $indexNames : [$indexNames];

        foreach ($indexNames as $i => $indexName) {
            $indexNames[$i] = $this->db->quoteColumnName($indexName);
        }

        return 'BUILD INDEX ' . $this->db->quoteBucketName($bucketName) . '(' . implode(', ', $indexNames) . ') USING GSI';
    }