Date: Tue, 16 Apr 2024 07:29:32 +0000
From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>,
	"Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>,
	Amit Kapila <amit.kapila16@gmail.com>
Subject: Re: Disallow changing slot's failover option in transaction block
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Hi,

On Tue, Apr 16, 2024 at 06:32:11AM +0000, Zhijie Hou (Fujitsu) wrote:
> Hi,
> 
> Kuroda-San reported an issue off-list that:
> 
> If user execute ALTER SUBSCRIPTION SET (failover) command inside a txn block
> and rollback, only the subscription option change can be rolled back, while the
> replication slot's failover change is preserved.

Nice catch, thanks!

> To fix it, I think we can prevent user from executing ALTER SUBSCRIPTION set
> (failover) inside a txn block, which is also consistent to the ALTER
> SUBSCRIPTION REFRESH/DROP SUBSCRIPTION command. Attach a small
> patch to address this.

Agree. The patch looks pretty straightforward to me. Worth to add this
case in the doc? (where we already mention that "Commands ALTER SUBSCRIPTION ...
REFRESH PUBLICATION and ALTER SUBSCRIPTION ... {SET|ADD|DROP} PUBLICATION ...
with refresh option as true cannot be executed inside a transaction block"

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com