Horton

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

Jelte Fennema-Nio <me@jeltef.nl>

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From: Jelte Fennema-Nio <me@jeltef.nl>
To: Dave Cramer <davecramer@gmail.com>
Cc: Robert Haas <robertmhaas@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: 2024-04-05T16:48:38Z
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 Fri, 5 Apr 2024 at 18:30, Dave Cramer <davecramer@gmail.com> wrote:
>> > I really intended the _pq_ prefix as a way of taking something out of
>> > the GUC namespace, not as a part of the GUC namespace that users would
>> > see. And I'm reluctant to go back on that. If we want to make
>> > pg_protocol.${NAME} mean a wire protocol parameter, well maybe there's
>> > something to that idea [insert caveats here]. But doesn't _pq_ look
>> > like something that was intended to be internal? That's certainly how
>> > I intended it.
>
>
> Is this actually used in practice? If so, how ?

No, it's not used for anything at the moment. This whole thread is
basically about trying to agree on how we want to make protocol
changes in the future in a somewhat standardized way. But using the
tools available that we have to not break connecting to old postgres
servers: ProtocolVersionNegotation messages, minor version numbers,
and _pq_ parameters in the startup message. All of those have so far
been completely theoretical and have not appeared in any client-server
communication.