Re: Add 64-bit XIDs into PostgreSQL 15

On Tue, Jan 4, 2022 at 05:49:07PM +0000, Finnerty, Jim wrote:
> Hi Maxim,
> I’m glad to see that you’re trying to carry the 64-bit XID work forward. I
> had not noticed that my earlier patch (also derived from Alexander Kortkov’s
> patch) was responded to back in September. Perhaps we can merge some of the
> code cleanup that it contained, such as using XID_FMT everywhere and creating a
> type for the kind of page returned by TransactionIdToPage() to make the code
> cleaner.
>
> Is your patch functionally the same as the PostgresPro implementation? If
> so, I think it would be helpful for everyone’s understanding to read the
> PostgresPro documentation on VACUUM. See in particular section “Forced
> shrinking pg_clog and pg_multixact”
>
> https://postgrespro.com/docs/enterprise/9.6/routine-vacuuming#
> vacuum-for-wraparound

Good point --- we still need vacuum freeze. It would be good to
understand how much value we get in allowing vacuum freeze to be done
less often --- how big can pg_xact/pg_multixact get before they are
problems?

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

If only the physical world exists, free will is an illusion.