RE: Conflict detection for update_deleted in logical replication

On Thursday, August 21, 2025 2:01 PM shveta malik <shveta.malik@gmail.com> wrote:
> 
> On Wed, Aug 20, 2025 at 12:12 PM Zhijie Hou (Fujitsu)
> <houzj.fnst@fujitsu.com> wrote:
> >
> >
> > I agree. Here is V63 version which implements this approach.
> >
> 
> Thank You for the patches.
> 
> > The retention status is recorded in the pg_subscription catalog
> > (subretentionactive) to prevent unnecessary retention initiation upon
> > server restarts. The apply worker is responsible for updating this
> > flag based on the retention duration. Meanwhile, the column is set to
> > true when retain_dead_tuples is enabled or when creating a new
> > subscription with retain_dead_tuples enabled, and it is set to false when
> retain_dead_tuples is disabled.
> >
> 
> +1 on the idea.
> 
> Please find few initial testing feedback:

Thanks for the comments.

> 
> 1)
> When it stops, it does not resume until we restart th server. It keeps on waiting
> in wait_for_publisher_status and it never receives one.
> 
> 2)
> When we do: alter subscription sub1 set (max_conflict_retention_duration=0);
> 
> It does not resume in this scenario too.
> should_resume_retention_immediately() does not return true due to
> wait-status on publisher.

Fixed in the V64 patches.


> 3)
> AlterSubscription():
>  * retention will be stopped gain soon in such cases, and
> 
> stopped gain --> stopped again

Sorry, I missed this typo in V64, I will fix it in the next version.

Best Regards,
Hou zj