Hi! I tested MergeRollupTask on an OFFLINE APPEND table using: 1month.mergeType = concat 1month.bucketTimePeriod = 1M Expected: daily segments -> one monthly segment Observed: one daily segment with hourly bucket_start_ts values -> 24 hourly merged segments The task completes successfully, but increases the number of segments. Is this expected behavior for a DATE_TIME column with granularity 1:HOURS?

I think 1M might be interpreted as 1 minute and not 1 month (month is not supported). Since your input granularity is hours, you might have 1 value for each hour which is why you get 24 segments

Thanks for clarifying!