Re: how reliable is pg_rewind?

On Sat, Aug 01, 2020 at 10:35:37AM -0700, Curt Kolovson wrote:
> 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.

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.
--
Michael