Now we have two data types xid and xid8. The first one (xid) makes a numeric ring, and xid8 are monotonous.
As per [1] "Unlike xid values, xid8 values increase strictly monotonically and cannot be reused in the lifetime of a database cluster."
As a consequence of [1] xid8 can have min/max functions (committed in [2]), which xid can not have.
When working on 64xid patch [3] we assume that even 64xid's technically can be wraparound-ed, although it's very much unlikely. I wonder what is expected to be with xid8 values at this (unlikely) 64xid wraparound?
What do you think about this? Wouldn't it be better to change xid8 to form a numeric ring like xid? I think it is necessary for any 64-wraparound-enabled implementation of 64xids.
