2014-03-04 23:09 GMT+09:00 Robert Haas <robertmh...@gmail.com>: > On Mon, Mar 3, 2014 at 5:15 PM, Stephen Frost <sfr...@snowman.net> wrote: >>> As I mentioned >>> up-thread, I'd really like to see FDW join push-down, FDW aggregate >>> push-down, parallel query execution, and parallel remote-FDW execution >>> and I don't see this CustomScan approach as the right answer to any of >>> those. >> >> In accordance with the above, what I'd like to see with this patch is >> removal of the postgres_fdw changes and any changes which were for that >> support. In addition, I'd like to understand why 'ctidscan' makes any >> sense to have as an example of what to use this for- if that's valuable, >> why wouldn't we simply implement that in core? I do want an example in >> contrib of how to properly use this capability, but I don't think that's >> it. > > I suggested that example to KaiGai at last year's PGCon. It may > indeed be something we want to have in core, but right now we don't. > > More generally, I think this discussion is focusing on the wrong set > of issues. The threshold issue for this patch is whether there is a > set of hook points that enable a workable custom-scan functionality, > and whether KaiGai has correctly identified them. In other words, I > think we should be worrying about whether KaiGai's found all of the > places that need to be modified to support a custom scan, and whether > the modifications he's made to each of those places are correct and > adequate. Whether he's picked the best possible example does not > strike me as a matter of principal concern, and it's far too late to > tell him he's got to go pick a different one at this point anyway. > That is definitely the point to be discussed here. Even though I *believe* I could put the callbacks needed to implement alternative join / scan, it may lead different conclusion from other person's viewpoint.
At least, I could implement a custom-scan as an alternative of join using postgres_fdw, however, it's uncertain whether I could cover all the possible case we should care about. So, I'd like to see comments from others. Thanks, -- KaiGai Kohei <kai...@kaigai.gr.jp> -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers