protected function getIndexSQLDeclaration(Index $index)
    {
        if (!$this->supportIndexes()) {
            throw PlatformException::methodNotSupported(__METHOD__);
        }

        if (!$index->isUnique()) {
            return 'INDEX '.$index->getName().' ('.implode(', ', $index->getColumnNames()).')';
        }

        return 'CONSTRAINT '.$index->getName().' UNIQUE ('.implode(', ', $index->getColumnNames()).')';
    }