On Wed, Mar 2, 2016 at 6:54 PM, Alexander Korotkov <a.korot...@postgrespro.ru> wrote: > If FDWs existed then Postgres XC/XL were being developed then I believe they > would try to build full-featured prototype of FDW based sharding. If this > prototype succeed then we could make a full roadmap.
Speaking here with my XC hat, that's actually the case. A couple of years back when I worked on it, there were discussions about reusing FDW routines for the purpose of XC, which would have been roughly reusing postgres_fdw + the possibility to send XID, snapshot and transaction timestamp to the remote nodes after getting that from the GTM (global transaction manager ensuring global data visibility and consistency), and have the logic for query pushdown in the FDW itself when planning query on what would have been roughly foreign tables (not entering in the details here, those would have not been entirely foreign tables). At this point the global picture was not completely set, XC being based on 9.1~9.2 and the FDW base routines were not as extended as they are now. As history has told, this global picture has never showed up, though it would should XC have been merged with 9.3. The point is that XC would have moved as using the FDW approach, as a set of plugins. This was a reason behind this email of 2013 on -hackers actually: http://www.postgresql.org/message-id/cab7npqtdjf-58wuf-xz01nkj7wf0e+eukggqhd0igvsod4h...@mail.gmail.com There were as well discussions about making the connection pooler a background worker and plug in that in a shared memory context that all backends connecting to this XC-like-postgres_fdw would use, though this is another story, for another time... -- Michael -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
