Re: almost-super-user problems that we haven't fixed yet

From: Nathan Bossart <nathandbossart(at)gmail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: almost-super-user problems that we haven't fixed yet
Date: 2023-01-19 17:54:21
Message-ID: 20230119175421.GA3934756@nathanxps13
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On Thu, Jan 19, 2023 at 11:40:53AM -0500, Robert Haas wrote:
> On Wed, Jan 18, 2023 at 4:14 PM Nathan Bossart <nathandbossart(at)gmail(dot)com> wrote:
>> On Wed, Jan 18, 2023 at 02:51:38PM -0500, Robert Haas wrote:
>> > Should (nfree < SuperuserReservedBackends) be using <=, or am I confused?
>> I believe < is correct. At this point, the new backend will have already
>> claimed a proc struct, so if the number of remaining free slots equals the
>> number of reserved slots, it is okay.
> OK. Might be worth a short comment.

I added one.

>> > What's the deal with removing "and no new replication connections will
>> > be accepted" from the documentation? Is the existing documentation
>> > just wrong? If so, should we fix that first? And maybe delete
>> > "non-replication" from the error message that says "remaining
>> > connection slots are reserved for non-replication superuser
>> > connections"? It seems like right now the comments say that
>> > replication connections are a completely separate pool of connections,
>> > but the documentation and the error message make it sound otherwise.
>> > If that's true, then one of them is wrong, and I think it's the
>> > docs/error message. Or am I just misreading it?
>> I think you are right. This seems to have been missed in ea92368. I moved
>> this part to a new patch that should probably be back-patched to v12.
> I'm inclined to commit it to master and not back-patch. It doesn't
> seem important enough to perturb translations.

That seems reasonable to me.

> Tushar seems to have a point about pg_use_reserved_connections vs.
> pg_use_reserved_backends. I think we should standardize on the former,
> as backends is an internal term.

Oops. This is what I meant to do. I probably flubbed it because I was
wondering why the parameter uses "connections" and the variable uses
"backends," especially considering that the variable for max_connections is
called MaxConnections. I went ahead and renamed everything to use

Nathan Bossart
Amazon Web Services:

Attachment Content-Type Size
v4-0001-Code-review-for-ea92368.patch text/x-diff 1.6 KB
v4-0002-Rename-ReservedBackends-to-SuperuserReservedConne.patch text/x-diff 4.1 KB
v4-0003-Introduce-reserved_connections-and-pg_use_reserve.patch text/x-diff 13.1 KB

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