public function getAddIndexDDL(Index $index)
    {
        $pattern = "
CREATE %sINDEX %s ON %s (%s);
";

        return sprintf($pattern,
            $index->isUnique() ? 'UNIQUE ' : '',
            $this->quoteIdentifier($index->getName()),
            $this->quoteIdentifier($index->getTable()->getName()),
            $this->getColumnListDDL($index->getColumnObjects())
        );
    }