Re: Add 64-bit XIDs into PostgreSQL 15

On Sat, Feb 7, 2026 at 5:47 PM Heikki Linnakangas <hlinnaka@iki.fi> wrote:
> The thing I like least about this is how the upgrade works, i.e. the
> conversion code and the "double xmax" hack. This would look much nicer
> if we could start from clean slate and just add the fields we need to
> the page header. However, upgrade is important, that point has been
> discussed a lot on the list, and I don't have any better ideas. I think
> it's as good as it gets at the high level.

I don't think the page header is the right thing, because that applies
to every AM, including both table AMs and index AMs. I'd say that some
of the things we already have in the page header don't really make
sense there -- in particular, pd_prune_xid, which is heap-specific. We
can't change that at this point, but we shouldn't make it worse.

-- 
Robert Haas
EDB: http://www.enterprisedb.com