Re: [PATCH] Clarify the behavior of the system when approaching XID wraparound

On Thu, Oct 12, 2023 at 12:01 PM Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
> No objections from me.

Here is a doc-only patch that I think could be back-patched as far as
emergency mode exists. It combines all of the wording changes to the
documentation from v1-v3 of the previous version, but without changing
the message text that is quoted in the documentation, and without
adding more instances of similar message texts to the documentation,
and with a bunch of additional hacking by me. Some things I changed:

- I made it so that the MXID section refers back to the XID section
instead of duplicating it, but with a short list of differences.
- I weakened the existing claim that says you must be a superuser or
VACUUM definitely won't fix it to say instead that you SHOULD run
VACUUM as the superuser, because the former is false and the latter is
true.
- I made the list of steps for recovering more explicit.
- I split out the bit about running autovacuum in the affected
database into a separate step to be performed after VACUUM for
continued good operation, rather than a necessary ingredient in
recovery, because it isn't.
- A bit of other minor rejiggering.

I'm not forgetting about the rest of the proposed patch set, or the
change I proposed earlier. I'm just posting this much now because this
is how far I got today, and it would be useful to get comments before
I go further. I think the residual portion of the patch set not
included in this documentation patch will be quite small, and I think
that's a good thing, but again, I don't intend to blow that off.

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