if either start or end time is not passed in, it will default to 0. In the https://github.com/twitter/hraven/blob/master/hraven-core/src/main/java/com/twitter/hraven/datasource/JobHistoryService.java#L274 , if start/end times are 0, they are not added to the scan. Hence by adding these parameters to REST api is enough to fix the issue of limiting the flows looked at given a time range