Re: failover logical replication slots

The parameter* sync_replication_slots* could be tested if it is set to true
before doing any action on failover slots.

Regards,
Fabrice

On Thu, Jun 12, 2025 at 12:06 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
wrote:

> On Thu, Jun 12, 2025 at 3:07 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
> wrote:
> >
> > On Thu, Jun 12, 2025 at 2:32 PM Fabrice Chapuis <fabrice636861(at)gmail(dot)com>
> wrote:
> > >
> >
> > > After the first failover, the following failovers will work given that
> the sync flag is true on both the primary and standby slots.
> > >
> > > After new sandby is attached to the primary, can we imagine that when
> the sync worker process is started we check if a failover slot exists on
> the standby, if so we drop it before recreating a new one for syncing?
> > >
> >
> > This has the risk of dropping an unwarranted slot.
> >
>
> On thinking further, even if we decide to support this functionality
> of overwriting the existing slots in some way, what is guarantee that
> the new standby will enable syncslot functionality (via
> sync_replication_slots)? If standby doesn't enable the
> sync_replication_slots then such slots will remain dangling and lead
> to the accumulation of WAL. So, I think the first thing to do is to
> avoid such cases, both for failover and non-failover slots. Then we
> should consider ways to allow overwriting existing slots on standby in
> the scenario you explained.
>
> --
> With Regards,
> Amit Kapila.
>