On 8 May 2014 04:33, Kouhei Kaigai <kai...@ak.jp.nec.com> wrote: > In case when it replaced join relations by ForeignScan, it will be almost > same as expected ForeignScan with join-pushed down. Unlike usual table scan, > it does not have actual relation definition on catalog, and its result > tuple-slot is determined on the fly. > One thing different from the remote-join is, this ForeignScan node may have > sub-plans locally, if FDW driver (e.g GPU execution) may have capability on > Join only, but no relation scan portion. > So, unlike its naming, I want ForeignScan to support to have sub-plans if > FDW driver supports the capability.
>From here, it looks exactly like pushing a join into an FDW. If we had that, we wouldn't need Custom Scan at all. I may be mistaken and there is a critical difference. Local sub-plans doesn't sound like a big difference. Have we considered having an Optimizer and Executor plugin that does this without touching core at all? -- Simon Riggs 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
