Re: Proposal to allow setting cursor options on Portals

On Wed, 4 Mar 2026 at 09:26, Dave Cramer <davecramer(at)gmail(dot)com> wrote:

>
>
> On Thu, 15 Jan 2026 at 16:06, Hannu Krosing <hannuk(at)google(dot)com> wrote:
>
>> First, let me say that I very much support getting this into the wire
>> protocol.
>>
>> As for ways to extend the protocol, I have been myself working on
>> another patch + extension where one can return extra info in
>> ReadyForQuery message
>>
>> The first things to add are
>> * CommitLSN so we can make use of ability to WAIT FOR LSN on replica
>> and two connection-pooling helpers
>> * a flag telling that there are HOLD CURSORS
>> * a flag telling that there are temp tables
>>
>> This extra feedback is enabled by setting a flag, so no flag --
>> nothing to confuse the client.
>> The extras themselves are uniform (length, tag, data) so client can
>> ignore any tag they do not recognize.
>>
>> On Thu, Jan 15, 2026 at 8:11 PM Dave Cramer <davecramer(at)gmail(dot)com> wrote:
>> >
>> >
>> > On Thu, 15 Jan 2026 at 14:00, Robert Haas <robertmhaas(at)gmail(dot)com>
>> wrote:
>> >>
>> ...
>> >> I think what I like least about this proposal is the feeling that
>> >> we're about to embark on a long slippery slope of changing the
>> >> protocol a little bit in every new PG version. The cancel key thing is
>> >> a small change, look here's another. If we just keep doing that, we'll
>> >> end up with either a lot of minor version bumps or a lot of
>> >> extensions. I don't foresee a good outcome either way. This is a
>> >> widely used, widely adopted protocol. The idea that we can just start
>> >> tweaking it a little bit every year and have nothing bad happened
>> >> seems wild, regardless of how we do the tweaking.
>>
>> I think "tweaking ait little bit" and only whhere needed is exactly
>> the right approach, if it can be cleanly isolated.
>>
>> My approach to protocol extension modulation *is* the ability to
>> enable different parts of the protocol individually.
>>
>> For example the protocol extension to allow cursor/portal flags could
>> be implemented this way
>>
>> Client has to set a flag to PROTOCOL_PORTAL_OPTIONS=true to tell the
>> server that new protocol messages are coming
>> - If flag setting fails, client will not send the new protocol messages
>> - If flag setting succeeds, then it is ok to send the new messages
>> corresponding to the flag.
>>
>> This way the extra packets are disconnected from protocol version and
>> can be enabled/disabled individually and per connection
>>
>> And it also lets one cleanly backport the change as needed without
>> affecting anything else.
>>
>> > This leaves us with an all or nothing solution, which practically means
>> we do nothing, since we have to wait until we have a sufficient backlog of
>> > changes or features to change the protocol. I see that as untenable,
>> unless you are now advocating for using extensions for everything ?
>> >
>> > Dave
>>
>
> I have modified the patch to use protocol options instead of protocol
> version
>

resending with a different patch name as I think the commitfest app won't
pick it up with the same name

>
> See new version attached
>