> I won't have a million active IDs at the same time, but I will, in total, > over time.
high(int32) returns 2_147_483_647, i'm sure that's more than enough. But, in any case, i can't think of many properties where you will need high values. In that case, i'm sure it won't be a problem to define by hand prop: uint64. But these will be the minority, so i would not bother into looking for complex solutions when we are talking about edge cases.
