2014-12-16 1:22 GMT+09:00 Robert Haas <robertmh...@gmail.com>: > On Mon, Dec 15, 2014 at 3:40 AM, Shigeru Hanada > <shigeru.han...@gmail.com> wrote: >> I'm working on $SUBJECT and would like to get comments about the >> design. Attached patch is for the design below. > > I'm glad you are working on this. > >> 1. Join source relations >> As described above, postgres_fdw (and most of SQL-based FDWs) needs to >> check that 1) all foreign tables in the join belong to a server, and >> 2) all foreign tables have same checkAsUser. >> In addition to that, I add extra limitation that both inner/outer >> should be plain foreign tables, not a result of foreign join. This >> limiation makes SQL generator simple. Fundamentally it's possible to >> join even join relations, so N-way join is listed as enhancement item >> below. > > It seems pretty important to me that we have a way to push the entire > join nest down. Being able to push down a 2-way join but not more > seems like quite a severe limitation.
Hmm, I agree to support N-way join is very useful. Postgres-XC's SQL generator seems to give us a hint for such case, I'll check it out again. -- Shigeru HANADA -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers