how reliable is pg_rewind?

[Curt Kolovson]

When trying to resync an old primary to become a new standby, I have found
that pg_rewind only works occasionally. How reliable/robust is pg_rewind,
and what are its limitations? We have observed that approx half our FPIs in
the WALs are due to XLOG/FPI_FOR_HINT. The only reason we've set
wal_log_hints=on is so that we can  use pg_rewind. But if pg_rewind is
unreliable, we would rather turn off wal_log_hints. Any info on the
reliability of pg_rewind and its limitations would be appreciated.

Thanks, Curt

Re: how reliable is pg_rewind?

[Curt Kolovson]

Thanks, Paul and Michael. I forgot to mention that we're using postgres
v10.12.

On Sun, Aug 2, 2020 at 10:29 PM Paul Förster 
wrote:

> Hi Curt, hi Michael,
>
> > On 03. Aug, 2020, at 03:58, Michael Paquier  wrote:
> >
> > On Sat, Aug 01, 2020 at 10:35:37AM -0700, Curt Kolovson wrote:
> >> Any info on the reliability of pg_rewind and its limitations would be
> appreciated.
> >
> > FWIW, we use it in production to accelerate the redeployment of
> > standbys in HA configuration for 4 years now in at least one product,
> > and it is present in upstream for since 9.5, for 5 years now.  So the
> > tool is rather baked at this stage of the game.
>
> same here. We use it with Patroni in failover cluster setups for about 2-3
> years now. It has not failed us yet.
>
> Cheers,
> Paul
>
>