On Mon, 9 Feb 2026 at 18:03, Heikki Linnakangas <[email protected]> wrote:
> > The point is that we still do not want to use FullTransactionID > everywhere. Only in some places related to visibility checks that need > to deal with XIDs stored on sidk, like heapam_visibility.c and clog.c, > and it will probably spill over to some other places. But things like > the proc array can continue to use 32-bit XIDs. > > We will still have the limitation that you cannot have two transactions > *running* that are more than 2 billion XIDs apart. I think that's fine, > and we should not try to lift that limitation as part of this patch. > > The aim of this patch is to make Postgres support 64-bit XIDs. This is why the TransactionID type size increases from 4 to 8 bytes. It also has an effect on the proc array, allowing two transactions that that are more than 2 billion XIDs apart to run at the same time. You couldn't store tuples that were more than 2 billion XIDs apart on a single heap page. That is correct. However, this annoying limitation comes only from the page format. Moreover, it looks like as long as we have a page format with a base, we will not be able to bypass this limitation. Yet, running transactions far apart is totally accepted. -- Best regards, Maxim Orlov.
