Thread

Re: Support named (destination) portals in extended proto for psql meta commands.

Kirill Reshke <reshkekirill@gmail.com> — 2025-12-17T06:40:37Z

Sami, Jelte, thank you for looking into this.

On Sat, 13 Dec 2025 at 18:48, Sami Imseih <samimseih@gmail.com> wrote:

>
> ```
> \portal name [max_rows]
>
> -- prepare the statements
> select from mytab limit $1 \parse p1
>
> -- bind/execute the statement, optionally to a portal
> \bind_named p1 10 \portal portalname \g
> \bind_named p1 50 \portal portalname \g
>
> -- bind/execute the statement, optionally to a portal, with max_rows
> \bind_named p1 50 \portal portalname 50 \g
> \bind_named p1 50 \portal portalname 40 \g
> ```
>
> The syntax may seem awkward, but we already do this with \bind,
> where the meta command is not at the start.
>
> ```
> select $ \bind 1 \g
> ```

The separate "\portal" command is the design I actually find
surprisingly simple and pretty. So, that's what I have implemented in
v1-0002.

I am now posting some WIP versions of changes. v1-0001 still needs
some comprehensive changes to the doc, but I decided to already post
something to this thread.
Another concern is changing the ABI of libpq. v1-0001 changes the
number of `PQsendQueryPrepared` parameters, and this is something that
has not been changed for 20+ years... Maybe the better choice would be
a new, separate function (which will still be just a proxy-function to
PQsendQueryGuts)?

Also, I think that we need to support closing destination portals
using psql meta-commands. The current design in my head is a separate
"'\close_cursor <name>" command. Since we still can cancel a portal
using SQL-level command (CLOSE), I think this should be separate
patches to the series.  WHYT?

-- 
Best regards,
Kirill Reshke