Re: Add new protocol message to change GUCs for usage with future protocol-only GUCs

Jelte Fennema-Nio <me@jeltef.nl>

From: Jelte Fennema-Nio <me@jeltef.nl>
To: Jacob Champion <jacob.champion@enterprisedb.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Dave Cramer <davecramer@gmail.com>, Peter Smith <smithpb2250@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Jacob Burroughs <jburroughs@instructure.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, "Andrey M. Borodin" <x4mmm@yandex-team.ru>, Pavel Stehule <pavel.stehule@gmail.com>, Jeff Davis <pgsql@j-davis.com>, Peter Eisentraut <peter@eisentraut.org>
Date: 2024-05-06T16:22:25Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →
  1. libpq: Add min/max_protocol_version connection options

  2. libpq: Handle NegotiateProtocolVersion message differently

  3. Add PQfullProtocolVersion() to surface the precise protocol version.

  4. Do not hardcode PG_PROTOCOL_LATEST in NegotiateProtocolVersion

  5. libpq: Handle NegotiateProtocolVersion message

  6. Provide for forward compatibility with future minor protocol versions.

On Tue, 23 Apr 2024 at 19:39, Jacob Champion
<jacob.champion@enterprisedb.com> wrote:
>
> On Mon, Apr 22, 2024 at 2:20 PM Jelte Fennema-Nio <me@jeltef.nl> wrote:
> > 1. I strongly believe minor protocol version bumps after the initial
> > 3.1 one can be made painless for clients/poolers (so the ones to
> > 3.2/3.3/etc). Similar to how TLS 1.3 can be safely introduced, and not
> > having to worry about breaking TLS 1.2 communication.
>
> Apologies for focusing on a single portion of your argument, but this
> claim in particular stuck out to me. To my understanding, IETF worried
> a _lot_ about breaking TLS 1.2 implementations with the TLS 1.3
> change, to the point that TLS 1.3 clients and servers advertise
> themselves as TLS 1.2 and sneak the actual version used into a TLS
> extension (roughly analogous to the _pq_ stuff). I vaguely recall that
> the engineering work done for that update was pretty far from
> painless.

My bad... I guess TLS 1.3 was a bad example, due to it changing the
handshake itself so significantly.