On Monday, October 15, 2012 10:03:40 PM Tom Lane wrote: > Robert Haas <robertmh...@gmail.com> writes: > > On Mon, Oct 15, 2012 at 3:18 PM, Peter Geoghegan <pe...@2ndquadrant.com> wrote: > >> On 15 October 2012 19:19, Bruce Momjian <br...@momjian.us> wrote: > >>> I think Robert is right that if Slony can't use the API, it is unlikely > >>> any other replication system could use it. > >> > >> I don't accept that. Clearly there is a circular dependency, and > >> someone has to go first - why should the Slony guys invest in adopting > >> this technology if it is going to necessitate using a forked Postgres > >> with an uncertain future? > > > > Clearly, core needs to go first. However, before we commit, I would > > like to hear the Slony guys say something like this: We read the > > documentation that is part of this patch and if the feature behaves as > > advertised, we believe we will be able to use it in place of the > > change-capture mechanism that we have now, and that it will be at > > least as good as what we have now if not a whole lot better. > > > > If they say something like "I'm not sure we have the right design for > > this" or "this wouldn't be sufficient to replace this portion of what > > we have now because it lacks critical feature X", I would be very > > concerned about that. > > The other point here is that core code without any implemented use-cases > is unlikely to be worth a tinker's damn. Regardless of what time-frame > the Slony guys are able to work on, I think we need to see working code > (of at least prototype quality) before we believe that we've got it > right. Or if not code from them, code from some other replication > project.
FWIW we (as in 2ndq), unsurprisingly, have a user of this which is in development atm. > A possibly-useful comparison is to the FDW APIs we've been slowly > implementing over the past couple releases. Even though we *did* have > some use-cases written right off the bat, we got it wrong and had to > change it in 9.2, and I wouldn't bet against having to change it again > in 9.3 (even without considering the need for extensions for non-SELECT > operations). And, despite our very clear warnings that all that stuff > was in flux, people have been griping because the APIs changed. On the other hand, I don't think we would have FDWs today at all if it wouldn't have been done that way. So I really cannot see that as an indication of not working incrementally. Obviously thats not an argument for not trying to get the API correct right off the bat. I seriously hope the userlevel API continues to be simpler than what FDWs need. Regards, Andres -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
