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Subject: Re: pg_createsubscriber does not check output_plugin_libraries
From: Chao Li <li.evan.chao@gmail.com>
In-Reply-To: 
 <OS9PR01MB12149E6DB23FD6B53CCC64403F5B02@OS9PR01MB12149.jpnprd01.prod.outlook.com>
Date: Tue, 15 Sep 2026 13:56:17 +0800
Cc: Jacob Champion <jacob.champion@enterprisedb.com>,
 Fujii Masao <masao.fujii@gmail.com>,
 "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
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To: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
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> On Sep 9, 2026, at 18:33, Hayato Kuroda (Fujitsu) =
<kuroda.hayato@fujitsu.com> wrote:
>=20
> Dear Fujii-san, Jacob,
>=20
> Thanks for giving feedbacks. I'm confusing and let me confirm few =
points.
> The situation might be different before and after the PG19.
>=20
> For PG17 and 18, FOR ALL TABLES publications for publisher databases,
> it meant superuser is required for the connection. IIUC superuser can =
bypass all
> permission checks thus it might be OK not to check these points.
> (We may have to check it though).
> As for the PG19 and HEAD, we allowed to re-use existing publications =
[1], it
> effectively allowed to use non-superuser for connecting to the =
publisher.
> However it meant additional permission checks might be needed like =
Jacob pointed
> out.
>=20
> In this thread I do not want to broaden for other points and focus on =
the added
> GUC, thought? In other threads we can improve --check option more.
>=20
> Based on that, permission check is actually needed for PG19/HEAD same =
check
> Fujii-san pointed out. For PG18/17, we may not have to take care the =
usage of
> current_setting() but same code is used for better understanding. =
Attached patch
> set does accordingly. v5-0001 also has a test for the case just in =
case, but not
> sure it should be pushed.
>=20
> [1]: =
https://github.com/postgres/postgres/commit/85ddcc2f4cdef490276d151c80459e=
287bceb782
>=20
> Best regards,
> Hayato Kuroda
> FUJITSU LIMITED
>=20
> =
<v5-PG17-0001-pg_createsubscriber-ensure-output_plugin_lib.txt><v5-PG18-00=
01-pg_createsubscriber-ensure-output_plugin_lib.txt><v5-PG18-0002-free-all=
ocated-memory-for-max_slot_wal_keep_.txt><v5-0001-pg_createsubscriber-ensu=
re-output_plugin_librarie.patch><v5-0002-free-allocated-memory-for-max_slo=
t_wal_keep_size.patch>

I have nit comment on 0001:
```
+/*
+ * Check per-database settings on the publisher
+ */
+static void
+check_publisher_per_database(const struct LogicalRepInfo *dbinfo)
```

I find the header comment slightly misleading. Although =
output_plugin_libraries is checked separately for each database =
connection, its effective value may come from database, role, or =
connection-level settings. So, maybe rephrase it as: Check effective =
settings for each publisher database.

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