Re: what to do after a failover

Thanks for the response.
I am using Postgresql 11.
I want something simple and I have a strong preference toward using stock
tools. After the promotion and the original master comes online, I was
thinking of doing a pg_basebackup to sync. Any thoughts about that? I had a
very hard time with pg_rewind and I didn't like its complexity.

On Wed, Jan 8, 2020 at 11:31 PM Michael Paquier <michael(at)paquier(dot)xyz> wrote:

> On Wed, Jan 08, 2020 at 11:06:28PM -0500, Rita wrote:
> > I run a master and standby setup with Postgresql 11. The systems are
> > identical from a hardware and software setup. If the master goes down I
> > can do a pg_ctl promote on the standby and point my applications to use
> the
> > standby (new master).
> >
> > Once the original master is online, when is an appropriate time to fail
> > back over? And are there any other things besides promote after the
> > failover is done?
>
> Make sure that you still have an HA configuration able to handle
> multiple degrees of failures with always standbys available after a
> promotion.
>
> The options available to rebuild your HA configuration after a
> failover depend on the version of PostgreSQL you are using. After a
> failover the most simple solution would be to always recreate a new
> standby from a base backup taken from the freshly-promoted primary,
> though it can be costly depending on your instance. You could also
> use pg_rewind (available in core since 9.5) to recycle the previous
> primary and reuse it as a standby of the new promoted custer. Note
> that there are community-based solutions for such things, like
> pg_auto_failover or pacemaker-based stuff just to name two. These
> rely on more complex architectures, where a third node is present to
> monitor the others (any sane HA infra ought to do at least that to be
> honest).
> --
> Michael
>

--
--- Get your facts first, then you can distort them as you please.--