| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Kouhei Kaigai <kaigai(at)ak(dot)jp(dot)nec(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, PgHacker <pgsql-hackers(at)postgresql(dot)org>, Stephen Frost <sfrost(at)snowman(dot)net>, Shigeru Hanada <shigeru(dot)hanada(at)gmail(dot)com>, Jim Mlodgenski <jimmy76(at)gmail(dot)com>, Peter Eisentraut <peter_e(at)gmx(dot)net>, Kohei KaiGai <kaigai(at)kaigai(dot)gr(dot)jp> |
| Subject: | Re: [v9.5] Custom Plan API |
| Date: | 2014-05-08 13:26:38 |
| Message-ID: | CA+U5nMJRoOYQd5FUBj-Dpc0U43qG28Sxt9EQxQvAD4Dhyw9cKQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On 8 May 2014 04:33, Kouhei Kaigai <kaigai(at)ak(dot)jp(dot)nec(dot)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
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