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: Kirill Reshke <reshkekirill@gmail.com>

Cc: Chao Li <li.evan.chao@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2025-11-27T02:46:10Z

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

On Thu, Nov 27, 2025 at 2:37 AM Kirill Reshke <reshkekirill@gmail.com> wrote:
> Looking at v3 raises two questions for me.
>
> First is if we should have a doc notion of which variables ought to be
> set to what.

Are you suggesting that we document which GUC parameters should be set,
and to what values, for logical replication? We already have a section on this
in logical-replication.sgml. Is that sufficient?


> Second, how do we actually test that subscription connection options
> are applied on the subscriber side? Can we have TAP for this  (is is
> worth the troubles)?

+1 on adding a test. One idea is to enable log_replication_commands via
the CONNECTION option and then check that the publisher’s log contains
the message "received replication command: IDENTIFY_SYSTEM".
There may be a cleaner way to test this, though.

Regards,

-- 
Fujii Masao