The way data tiering performs rotation is not as straightforward, but if you are after 1d rotation, you can have a 1 day gap between the min/max. For example, if you want to retain data for 30 days, you can set min to 30 and max to 31. The reason is that graylog uses the “leeway” in the event the index has not grown enough in size to rotate.
This is a basic diagram of the decision tree that happens. You can see the section where “Index Create Date > (Max Age - Min Age)”
