"Ed L." <pgsql@bluepolka.net> writes:
>> XIDs are issued in transaction start order, not transaction commit
>> order. Dunno if that's what's concerning you.
> Yes, I'm interested in any reliable ordering of transaction commits for the
> purpose of serial asyncronous replication. Is that possible?
The order in which commit records are inserted into the WAL log would
work (and if you just need an ID number, the commit records' WAL-log
addresses are 64-bits and would serve nicely). But you'll have to add
code to the backend to get at that.
regards, tom lane