Re: Propose: Adding a '--enable-failover' option to 'pg_createsubscriber'

Hi, Evan

thanks for your comments.

I modified like a attached patch file.
I used pgindent, thank you.

CreateSubscriberOptions.failover is used in CREATE SUBSCRIPTION,
but LogicalRepInfos.failover is used in pg_create_logical_replication_slot()
so I left these comments as is.

ioseph


On Thu, Dec 11, 2025 at 07:28:13AM +0800, Chao Li wrote:
> 
> > On Dec 10, 2025, at 17:03, Ioseph Kim <pgsql-kr@postgresql.kr> wrote:
> > 
> > Hi
> > 
> > A failover option has been added to the CREATE SUBSCRITION command, but this functionality isn't easily accessible using the pg_createsubscriber tool.
> > 
> > Subscriptions created using pg_createsubscriber must be configured for failover via an alter operation.
> > 
> > To address this issue, we've added a simple --enable-failover option to the pg_createsubscriber tool.
> > 
> > This patch is simple. It doesn't handle exceptions or provide any TAP test code.
> > 
> > Please review this and we hope the development team will refine it further.
> > 
> > ioseph
> > <0001-Adding-a-enable-failover-option-to-pg_createsubscrib.patch>
> 
> Hi, Ioseph,
> 
> Thanks for the patch. I consider adding the “(failover=true)” option is useful. A few small comments:
> 
> 1
> ```
> +      <para>
> +       Enables <link linkend="sql-createsubscription-params-with-failover"><literal>failover</literal></link>
> +       commit for the subscription.
> +       The default is <literal>false</literal>.
> +      </para>
> ```
> 
> This doc change is confusing. What is “failover commit”? I guess you meant “failover option”?
> 
> I’d suggest a phrase like:
> 
> “Enables the subscription’s failover option, allowing its logical replication slot to be used after failover.”
> 
> 2
> ```
> +	printf(_("      --enable-failover           enable failover\n"));
> ```
> 
> If we look at the existing “—enable-two-phase” help text, we consider this help text is too simple. I’d suggest: enable syncing replication slots associated with the subscription.
> 
> 3
> ```
> --- a/src/bin/pg_basebackup/pg_createsubscriber.c
> +++ b/src/bin/pg_basebackup/pg_createsubscriber.c
> @@ -49,6 +49,7 @@ struct CreateSubscriberOptions
>  	int			recovery_timeout;	/* stop recovery after this time */
>  	bool		all_dbs;		/* all option */
>  	SimpleStringList objecttypes_to_clean;	/* list of object types to cleanup */
> +	bool       failover;		/* enable failover option of subscription */
>  };
>  
>  /* per-database publication/subscription info */
> @@ -73,6 +74,7 @@ struct LogicalRepInfos
>  {
>  	struct LogicalRepInfo *dbinfo;
>  	bool		two_phase;		/* enable-two-phase option */
> +	bool		failover;		/* enable failover option of logical replication slot */
>  	bits32		objecttypes_to_clean;	/* flags indicating which object types
>  										 * to clean up on subscriber */
>  };
> ```
> 
> Add comments for “failover” in the two structures are inconsistent. The latter one is incorrect, the option is for “create subscription” command but for a slot.
> 
> 4 You need to run pgindent as I saw some format problems.
> 
> Best regards,
> --
> Chao Li (Evan)
> HighGo Software Co., Ltd.
> https://www.highgo.com/
> 
> 
> 
>