Alvaro,
>> This sounds like extending Xid to 64 bits, without having to store the
>> high bits everywhere. Was this discussed in the PGCon devs meeting?
Essentially, yes.
One of the main objections to raising XID to 64-bit has been the per-row
overhead. But adding 4 bytes per page wouldn't be much of an impact.
--
-- Josh Berkus
PostgreSQL Experts Inc.
http://www.pgexperts.com