Thread: PG18 protocol version

In the PG18 docs, I see:
https://www.postgresql.org/docs/18/protocol-message-formats.html

StartupMessage (F)
:
Int32(196608)

    The protocol version number. The most significant 16 bits are the
    major version number (3 for the protocol described here). The
    least significant 16 bits are the minor version number (0 for the
    protocol described here).

In my understanding PG18 will support protocol version 3.2, but above
statement claims that the protocol minor version is 0. Initially I
thought this is because libpq will use 3.0 unless max_protocol_version
is specified as a connection string. But in the BackendKeyData section
of the doc, it clearly explains v3.2 format. So I suspect this is just
a typo.

Best regards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp

On Thu, 26 Jun 2025 at 08:56, Tatsuo Ishii <ishii@postgresql.org> wrote:
> So I suspect this is just a typo.

Yeah it seems we didn't update this part of the docs. Attached is a
patch to fix that.

> I didn't? I replaced it with a more generic version of the same
> information, that covers both protocol version 3.0 and 3.2 (and any
> future 3.x)

I meant this.
>> -         (0 for the protocol described here).

With your patch the explanation that this document (Message Formats)
is for 3.2, is gone. But maybe it's okay since "54.1.4. Protocol
versions" already stats that the whole F/B protocol docs is for 3.2.

What do you think?
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp