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

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

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

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

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

Date: 2025-11-21T09:23:10Z

Lists: pgsql-hackers

Commits

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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 Nov 21, 2025, at 15:47, Fujii Masao <masao.fujii@gmail.com> wrote:
> 
>> 
>> 4. The commit message:
>> ```
>> This commit removes the restriction by changing how logical replication
>> connections are established so that GUC settings in the CONNECTION string
>> are properly passed through to and uesd by the walsender. This enables
>> ```
>> 
>> This is a little bit inaccurate, all user specified settings expected the 3 ones being overwritten will be honored.
> 
> Are you suggesting that, because datestyle and the other two parameters
> specified in CONNECTION aren(t actually applied by the walsender,
> the commit message should explicitly mention that not all parameters
> from CONNECTION are used?

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.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/