* make additional queries to pull source data while the
* main query is still running.
*
- * @param DatabaseBase $db
+ * @param IDatabase $db
* @param int|array $history One of WikiExporter::FULL, WikiExporter::CURRENT,
* WikiExporter::RANGE or WikiExporter::STABLE, or an associative array:
* - offset: non-inclusive offset at which to start the query