Re: Safe switchover

Greetings,

* Paul Förster (paul.foerster@gmail.com) wrote:
> > On 10. Jul, 2020, at 17:29, Stephen Frost <sfrost@snowman.net> wrote:
> > Patroni also has the option to use pgbackrest instead of pg_rewind.
>
> right. Sorry, I forgot about that. We use pg_rewind which works great.

Sure, if you know exactly why the former primary failed and have
confidence that nothing actually bad happened then pg_rewind can work
(though it's still not what I'd generally recommend).

If you don't actually know what happened to the former primary to cause
it to fail then I definitely wouldn't use pg_rewind on it since it
doesn't have any checks to make sure that the data is actually
generally consistent.  These days you could get a bit of a better
feeling by running pg_checksums against the data dir, but that's not
going to be as good as doing a pgbackrest delta restore when it comes to
making sure that everything is valid.

Thanks,

Stephen