public function addIndex($table, $columnNames, $indexName = '')
    {
        $table = $this->prefixTable($table);

        if (!is_array($columnNames)) {
            $columnNames = array($columnNames);
        }

        return $this->container->make('Piwik\Updater\Migration\Db\AddIndex', array(
            'table' => $table, 'columnNames' => $columnNames, 'indexName' => $indexName
        ));
    }