Обсуждение: Is a logical replication crash recovery safe?
Is a logical replication crash recovery safe?
Thanks, Markus
> On Jan 24, 2023, at 07:37, Zwettler Markus (OIZ) <Markus.Zwettler@zuerich.ch> wrote: > > Is a logical replication crash recovery safe? You might want to give more detail about the scenario you are concerned about. Changes that are received by a subscriberas part of logical replication are WAL-logged, observe transaction semantics, and will be replayed if the subscribercrashes and restarts.
> -----Ursprüngliche Nachricht----- > Von: Christophe Pettus <xof@thebuild.com> > Gesendet: Dienstag, 24. Januar 2023 16:48 > An: Zwettler Markus (OIZ) <Markus.Zwettler@zuerich.ch> > Cc: pgsql-general@lists.postgresql.org > Betreff: [Extern] Re: Is a logical replication crash recovery safe? > > > > > On Jan 24, 2023, at 07:37, Zwettler Markus (OIZ) <Markus.Zwettler@zuerich.ch> > wrote: > > > > Is a logical replication crash recovery safe? > > You might want to give more detail about the scenario you are concerned about. > Changes that are received by a subscriber as part of logical replication are WAL- > logged, observe transaction semantics, and will be replayed if the subscriber > crashes and restarts. > Sorry. Let me refine. If I create a logical replication slot and use the replication slot to publish some tables. Will the information in the replication slot be safe for any subscription even if a crash recovery happened on the publishernode?
Markus,
Yesterday EDB published the (open source) pg_failover_slots extension, aimed at pushing logical slot information on standbys: without it, that information is kept on the master only, so you have to rebuild the logical replication topology on switch/fail-overs.
Obviously, if the promoted server is outdated wrt to the lost master, you could still have problems with subscriptions, although there some configuration that tries to address that problem too (standby_slots_min_confirmed).
For the moment being you can find the documentation at EDB's docs, and the sources at github.com/EnterpriseDB/pg_failover_slots. I hope the extension will make quickly its way to PGDG as prebuilt packages.
Best,
g
On Tue, 24 Jan 2023 at 17:08, Zwettler Markus (OIZ) <Markus.Zwettler@zuerich.ch> wrote:
> -----Ursprüngliche Nachricht-----
> Von: Christophe Pettus <xof@thebuild.com>
> Gesendet: Dienstag, 24. Januar 2023 16:48
> An: Zwettler Markus (OIZ) <Markus.Zwettler@zuerich.ch>
> Cc: pgsql-general@lists.postgresql.org
> Betreff: [Extern] Re: Is a logical replication crash recovery safe?
>
>
>
> > On Jan 24, 2023, at 07:37, Zwettler Markus (OIZ) <Markus.Zwettler@zuerich.ch>
> wrote:
> >
> > Is a logical replication crash recovery safe?
>
> You might want to give more detail about the scenario you are concerned about.
> Changes that are received by a subscriber as part of logical replication are WAL-
> logged, observe transaction semantics, and will be replayed if the subscriber
> crashes and restarts.
>
Sorry. Let me refine.
If I create a logical replication slot and use the replication slot to publish some tables.
Will the information in the replication slot be safe for any subscription even if a crash recovery happened on the publisher node?