I mean, I'm not sure this is the place to get into detailed schema discussions, but I think I wouldn't use a row_id here at all, certainly, there's no need for

I mean, I'm not sure this is the place to get into detailed schema discussions, but I think I wouldn't use a row_id here at all, certainly, there's no need for this to be unique across all of the rows, you could make a unique constraint on user_id, time, row_id and then provide all 3 of them for the deletes, if the only reason is for the deletes, then that should be fine. If there are other reasons, then you probably have a different unique constraint that has some real world meaning (and that likely involves time).