CancelRequest(F) documentation.

Started by Dmitriy Igrishin12 months ago3 messagesdocs
Beta feature

Hackorum builds and tests every patch posted to the lists, not only commitfest submissions. This is Hackorum's own CI rather than the PostgreSQL project's, and it is still under testing - please report anything that looks wrong.

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You can run a PostgreSQL built from this patch straight from Docker, with no checkout and no build:

docker run --rm -p 5432:5432 ghcr.io/hackorum-dev/postgres-patch:t77886
psql -h localhost -U postgres

Built from patchset v2 (message #2), July 27, 2026 at 07:13 AM.

Every patchset is also pushed to a branch of our PostgreSQL fork, so you can check out the same tree CI built. Without a PostgreSQL checkout:

git clone --branch t77886_2 https://github.com/hackorum-dev/postgres.git

In a checkout you already have, add the fork once:

git remote add hackorum https://github.com/hackorum-dev/postgres.git

then, for this patchset and every later one:

git fetch hackorum t77886_2 && git checkout t77886_2

Patchset v2 (message #2) is on t77886_2

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#1Dmitriy Igrishin
dmitigr@gmail.com

Hello,

CancelRequest(F) documentation at
https://www.postgresql.org/docs/18/protocol-message-formats.html#PROTOCOL-MESSAGE-FORMATS-CANCELREQUEST
seems to be inconsistent for protocol 3.2. It is stated here that the
length of the message is always 16 bytes (specified as Int32(16)),
however the maximum message length actually depends on the secret key
length (which can be up to 256 bytes, as also stated in the
documentation.)

I would propose to specify the overall message length as Int32 in the
documentation for PostgreSQL 18+.

Thanks.

#2Jelte Fennema-Nio
postgres@jeltef.nl
In reply to: Dmitriy Igrishin (#1)
Re: CancelRequest(F) documentation.

On Tue Oct 7, 2025 at 6:08 PM CEST, Dmitry Igrishin wrote:

CancelRequest(F) documentation at
https://www.postgresql.org/docs/18/protocol-message-formats.html#PROTOCOL-MESSAGE-FORMATS-CANCELREQUEST
seems to be inconsistent for protocol 3.2. It is stated here that the
length of the message is always 16 bytes (specified as Int32(16)),
however the maximum message length actually depends on the secret key
length (which can be up to 256 bytes, as also stated in the
documentation.)

Good catch. Attached is a patch that fixes this.

Attachments:

t77886_2
v1-0001-docs-Fix-protocol-version-3.2-message-format-of-C.patchtext/x-patch; charset=utf-8; name=v1-0001-docs-Fix-protocol-version-3.2-message-format-of-C.patchDownload+1-2
#3Magnus Hagander
magnus@hagander.net
In reply to: Jelte Fennema-Nio (#2)
Re: CancelRequest(F) documentation.

On Mon, 13 Oct 2025 at 11:57, Jelte Fennema-Nio <postgres@jeltef.nl> wrote:

On Tue Oct 7, 2025 at 6:08 PM CEST, Dmitry Igrishin wrote:

CancelRequest(F) documentation at

https://www.postgresql.org/docs/18/protocol-message-formats.html#PROTOCOL-MESSAGE-FORMATS-CANCELREQUEST

seems to be inconsistent for protocol 3.2. It is stated here that the
length of the message is always 16 bytes (specified as Int32(16)),
however the maximum message length actually depends on the secret key
length (which can be up to 256 bytes, as also stated in the
documentation.)

Good catch. Attached is a patch that fixes this.

Thanks, pushed!

--
Magnus Hagander
Me: https://www.hagander.net/ <http://www.hagander.net/&gt;
Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/&gt;