Re: Add 64-bit XIDs into PostgreSQL 15

Hi, Hackers!

> Hi! Here is updated version of the patch, based on Alexander's ver16.
>
I'd like to add a few quick notes on what's been done in v17.

Patches 0001 and 0002 that are planned to be committed to PG15 are almost
unchanged with the exception of one unnecessary cast in 0002 removed.

We've also addressed several issues in patch 0005 (which is planned for
PG16):
- The bug with frozen xids after pg_upgrade, reported by Justin [1]
- Added proper processing of double xmax pages in
HeapPageSetPruneXidInternal()
- Fixed xids comparison. Initially in the patch it was changed to simple <
<= => > for 64 bit values. Now v17 patch has returned this to the way
similar to what is used in STABLE for 32-bit xids, but using modulus-64
numeric ring. The main goal of this change was to fix SRLU tests that
were mentioned
by Alexander to have been disabled. We've fixed and enabled most of them,
but some of them are still need to be fixed and enabled.

Also, we've pgindent-ed all the patches.

As patches that are planned to be delivered to PG15 are almost unchanged, I
completely agree with Alexander's plan to consider these patches (0001 and
0002) as RfC.

All activity, improvement, review, etc. related to the whole patchset is
also very much appreciated. Big thanks to Alexander for working on the
patch set!

[1]
https://www.postgresql.org/message-id/20220115063925.GS14051%40telsasoft.com

--
Best regards,
Pavel Borisov

Postgres Professional: http://postgrespro.com <http://www.postgrespro.com>