Re: .ready and .done files considered harmful

On Wed, May 5, 2021 at 4:13 PM Stephen Frost  wrote:
> I would think something like that would be alright and not worse than
> what we've got now.

OK.

> That said, in an ideal world, we'd have a way to get the new timeline to
> switch to in a way that doesn't leave open race conditions, so as long
> we're talking about big changes to the way archiving and archive_command
> work (or about throwing out the horrible idea that is archive_command in
> the first place and replacing it with appropriate hooks such that
> someone could install an extension which would handle archiving...), I
> would hope we'd have a way of saying "please, atomically, go get me a new
> timeline."
>
> Just as a reminder for those following along at home, as I'm sure you're
> already aware, the way we figure out what timeline to switch to when a
> replica is getting promoted is that we go run the restore command asking
> for history files until we get back "nope, there is no file named
> 0000123.history", and then we switch to that timeline and then try to
> push such a history file into the repo and hope that it works.

Huh, I had not thought about that problem. So, at the risk of getting
sidetracked, what exactly are you asking for here? Let the extension
pick the timeline using an algorithm of its own devising, rather than
having core do it? Or what?

-- 
Robert Haas
EDB: http://www.enterprisedb.com