Re: Should we remove vacuum_defer_cleanup_age? - Mailing list pgsql-hackers

From Greg Stark
Subject Re: Should we remove vacuum_defer_cleanup_age?
Date
Msg-id CAM-w4HMDy=vrbE7KEQmaRi-Dtg0jKh3jxa4z6+7cBA11K4T6ew@mail.gmail.com
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In response to Re: Should we remove vacuum_defer_cleanup_age?  (Laurenz Albe <laurenz.albe@cybertec.at>)
List pgsql-hackers
On Fri, 14 Apr 2023 at 13:15, Laurenz Albe <laurenz.albe@cybertec.at> wrote:
>
> On Fri, 2023-04-14 at 18:43 +0200, Alvaro Herrera wrote:
> > On 2023-Apr-14, Greg Stark wrote:
> > > I assume people would use hot_standby_feedback if they have streaming
> > > replication.
> >
> > Yes, either that or a replication slot.
>
> A replication slot doesn't do anything against snapshot conflicts,
> which is what we are discussing here.  Or are we not?

They're related -- the replication slot holds the feedback xmin so
that if your standby disconnects it can reconnect later and not have
lost data in the meantime. At least I think that's what I think it
does -- I don't know if I'm just assuming that, but xmin is indeed in
pg_replication_slots.

-- 
greg



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