On Mon, Jun 13, 2011 at 6:56 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: >> On Mon, Jun 13, 2011 at 12:38 PM, Dave Page <dp...@pgadmin.org> wrote: >>> BTW; it seems to me this should be documented, as it could really hack >>> off developers. I can't see anything in the docs to imply the API >>> might be radically redesigned. > >> And I'm still unconvinced that it's needed. I think we're going to >> end up adding on things that are missing and maybe replacing things >> that are just stubs, but I don't see why we'd whack it around just for >> fun. > > I think we're talking past each other. The point I'm trying to make is > that there are no defined/documented APIs for most of the planner, and > so any FDW that needs to do nontrivial planning stuff will need to reach > into pieces of the code that we've historically felt free to change as > needed. We can't just suddenly decide that all that code is now locked > down on the grounds that somebody might be touching it. As an example, > assuming that I figure out how to do generalized parameterized inner > plans in 9.2, whether or not the changes required might break somebody's > FDW is simply not going to be a consideration.
Hmm, I wonder if you're correct (as usual :-p). I thought you were talking about the API as defined here: http://www.postgresql.org/docs/9.1/static/fdw-routines.html, not internal planner stuff. I agree that if I use that (and I have, but only minimally), it should be on my own head. > In practice this might turn out to be less of a problem than Dave > thinks. We've made plenty of changes in the past that could affect > third-party selectivity functions, and lately we've been adding planner > hooks that likewise are seeing call contexts that change from version to > version; but I've not heard very many complaints about those > instabilities. I've certainly seen similar issues with the debugger plugin for example - but that's not using a documented API, bar a couple of hooks. > So maybe the average FDW won't find this to be a big > deal either. What I was reacting to at the start of this sub-thread was > the idea that the remote-postgresql FDW in particular would be > cross-version compatible. That's not an "average" FDW; I think that it > will have enough planner dependencies to be a poster child for these > issues. That I can understand - you'll have to forgive me for reading more into "making an FDW work on both 9.1 and 9.2 would be an exercise in frustration, if it's even possible." though :-) -- Dave Page Blog: http://pgsnake.blogspot.com Twitter: @pgsnake EnterpriseDB UK: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
