Re: Replication origins and timelines

Craig,

* Craig Ringer (craig(at)2ndquadrant(dot)com) wrote:
> TL;DR: replication origins track LSN without timeline. This is
> ambiguous when physical failover is present since XXXXXXXX/XXXXXXXX
> can now represent more than one state due to timeline forks with
> promotions. Replication origins should track timelines so we can tell
> the difference, I propose to patch them accordingly for pg11.

Uh, TL;DR, wow? Why isn't this something which needs to be addressed
before PG10 can be released? I hope I'm missing something that makes
the current approach work in PG10, or that there's some reason that this
isn't a big deal for PG10, but I'd like a bit of info as to why that's
the case, if it is.

The further comments in your email seem to state that logical
replication will just fail if a replica is promoted. While not ideal,
that might barely reach the point of it being releasable, but turns it
into a feature that I'd have a really hard time recommending to anyone,
and are we absolutely sure that there aren't any cases where there might
be an issue of undetected promotion, leading to the complications which
you describe?

Thanks!

Stephen