Re: Allow GUC settings in CREATE SUBSCRIPTION CONNECTION to take effect

Fujii Masao <masao.fujii@gmail.com>

From: Fujii Masao <masao.fujii@gmail.com>

To: Chao Li <li.evan.chao@gmail.com>

Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2025-11-22T14:14:27Z

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 →

Add TAP test for GUC settings passed via CONNECTION in logical replication.
- ec8d91c7e78c 15.16 landed
- 67edd54f0639 16.12 landed
- 358784645eb8 17.8 landed
- 6ec596815125 18.2 landed
- 5f13999aa11d 19 (unreleased) landed
Honor GUC settings specified in CREATE SUBSCRIPTION CONNECTION.
- f7eb44e0f087 15.16 landed
- 75f3428f2436 16.12 landed
- 7a990e801a72 17.8 landed
- 797fc5d1b38d 18.2 landed
- d926462d8190 19 (unreleased) landed
Ensure consistent logical replication of datetime and float8 values.
- f3d4019da5d0 15.0 cited

Attachments

v3-0001-Honor-GUC-settings-specified-in-CREATE-SUBSCRIPTI.patch (application/octet-stream) patch v3-0001

On Sat, Nov 22, 2025 at 10:31 AM Chao Li <li.evan.chao@gmail.com> wrote:
>
>
>
> > On Nov 22, 2025, at 00:14, Fujii Masao <masao.fujii@gmail.com> wrote:
> >
> > On Fri, Nov 21, 2025 at 6:24 PM Chao Li <li.evan.chao@gmail.com> wrote:
> >> No, what I was thinking is that, we could combine the three set statement into one, like:
> >>
> >> ```
> >> Set a = 1; set b = 2; set c = 3;
> >> ```
> >> So that sends a single statement to publisher server, that reduces round-trip from 3 times to one time.
> >
> > I see the point about combining the three SET commands to reduce round trips,
> > but I think the current approach in the patch (i.e., issuing a separate
> > SET command for each parameter) is sufficient. I still don't think
> > the additional round trip during replication connection startup is
> > a real concern. This approach is also consistent with what postgres_fdw
> > and pg_dump already do.
> >
>
> No problem. I don’t have a strong option here. I just saw you mentioned overhead of round trip and thought to improve. But I agree that overhead is tiny, not a real concern.

Okay, thanks!

I've updated the patch to use lengthof() as you suggested.
The revised version is attached.

Regards,

-- 
Fujii Masao