On Thu, May 21, 2020 at 5:38 PM Santhosh Kumar wrote:
>
> Hi Forum,
> If I have a cluster with Synchronous replication enabled with three nodes,
> for eg:
>
> [primary] [hot stand by 1] [host stand by 2]
>
> And for some unforeseen reasons, if primary fails, the failover will kick in
> and hot stand by 1 will become new primary and cluster setup will look like
> this
>
> [new primary (hot stand by1)] [host stand by 2]
>
> My question here is, what will happen if the original primary which has
> failed comes back. Will it become part of this high available replica cluster
> automatically or it will be stale and disconnected from the cluster?
>
It won't become standby automatically as it would have diverged from
the new master.
> How can we automatically make the failed primary to be part of the cluster
> with hot standby role? It would be of great help, if you can direct me to any
> references details. Thank you, upfront.
>
I think pg_rewind can help in such situations. See the docs of pg_rewind [1].
[1] - https://www.postgresql.org/docs/devel/app-pgrewind.html
--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com
